Transcatheter
Treatment of Pulmonary Obstruction: A Review P. Syamasundar
P
ULMONARY STENOSIS can occur as an isolated congenital cardiac defect or in association with other congenital cardiac abnormalities. The pulmonary outflow obstruction is most commonly located at the pulmonary valve level, although it can be subvalvar or supravalvar. The treatment approach has been surgical relief of the stenosis by direct enlargement of the constricted area, especially for isolated obstructions, or bypass of the obstruction by systemic-to-pulmonary artery anastomosis if total surgical correction is not feasible. Since the description by Kan and associates’ of the application of balloon dilatation techniques in children, we and others have used the technique to relieve congenital and acquired obstructive lesions in infants and children. The role of balloon dilation and other transcatheter techniques in the management of pulmonary outflow tract obstruction will be examined in this review. Our personal experience with this technique’-I3 and that reported in the literature will be used as supportive material. For the purpose of presentation, the case material will be divided into the following groups: (1) isolated valvar pulmonary stenosis, (2) supravalvar pulmanic stenosis, (3) pulmonary stenosis with interatrial right-to-left shunt, (4) pulmonary stenosis with ventricular right-to-left shunts, (5) narrowed systemic-to-pulmonary artery shunts, and (6) pulmonary atresia. Branch pulmonary artery stenosis will not be discussed in this review. ISOLATED
PULMONARY
VALVE
STENOSIS
Valvular pulmonary stenosis constitutes 7.5% to 9.0% of all congenital heart defects.24J5 The pathological features of pulmonary stenosis vary,26-2Rbut the most commonly found pathology is what is described as “dome-shaped” pulmonary valve. The “fused” pulmonary valve leaflets protrude from their attachment into the pulmonary artery as a conical or dome-shaped structure. The size of the orifice of the pulmonary valve may vary from a pinhole to several millimeters, most commonly central in location but can be eccentric. Raphae, presumably repreProgress
in Cardiovascular
Diseases,
Vol XXXV,
No 2 (September/October),
Outflow Tract
Rao
senting fused valve leaflet commissures, extend from the stenotic valve orifice to a varying extent down into the base of the dome-shaped valve. The number of raphae vary from none to seven. Children with pulmonic stenosis usually present with asymptomatic murmurs although they can present with signs of systemic venous congestion (usually interpreted as congestive heart failure) due to severe right ventricular dysfunction. Clinical findings of an ejection systolic click and ejection systolic murmur at the left upper sternal border, right ventricular hypertrophy on an electrocardiogram, prominent main pulmonary artery segment on a chest roentgenogram, and increased Doppler flow velocity in the main pulmonary artery are characteristic for this anomaly. When the pulmonary valvar obstruction is moderate to severe, relief of the obstruction is recommended to treat symptoms, if present, or to prevent right ventricular fibrosis and dysfunction. Until recently, surgical valvotomy was the only treatment available, but at the present time, relief of pulmonary valve obstruction can be accomplished by balloon valvuloplasty. Rubio-Alvarez and Limon-LasonZ9,“’ in the early 1950s described a technique by which pulmonic valve stenosis could be relieved via a catheter; they used a ureteral catheter with a wire. Twenty-five years later, Semb and associates3i used a Berman balloon angiographic catheter to produce rupture of the pulmonary valve (commissures); they withdrew an inflated balloon from the main pulmonary artery to the right ventricle and reduced the pulmonary valve
From the Department of Pediatrics, Division of Pediatric Cardiology, University of Wisconsin Medical School, Madison, WI. Supported in part by a grant ffom Oscar Rennobohm Foundation, Inc., Madison, WI. Address reprint requests to P. Syamasundar Rao, MD, Professor and Head, Division of Pediatric Cardioiogy, H41416 CSC, University of Wisconsin Children’s Hospital. 600 Highland Ave, Madison, WI 53792-4108. Copyright 0 1992 by W. B. Saunders Company 0033.0620/9213502-0003$5.0010 1992:
pp 119-158
119
120
gradient. More recently, Kan and associates’ used a static dilatation technique (similar to that used by Dotter and Judkins3? and Gruntzig and his associates33,34) in which they introduced a deflated balloon across the pulmonic valve and inflated the balloon; the radial forces of balloon inflation produced relief of pulmonary valve obstruction. This static dilatation technique is what is currently used. Indications
By and large, the indications for balloon dilatation of pulmonic stenosis are essentially the same as those used for surgical intervention. The indications for surgical pulmonary valvotomy are reasonably clear; patients with a moderate to severe degree of stenosis irrespective of the symptoms are candidates for surgical relief of the obstruction.35s36 The indications for balloon valvuloplasty appear less clear and are rarely defined. In 1988, careful examination’l of all studies available at that time showed that many patients with what may be considered mild pulmonic stenosis (natural history study definition3? gradient < 2.5 mm Hg, trivial; 25 to 49 mm Hg, mild; 50 to 79 mm Hg, moderate; and 2 80 mm Hg, severe) underwent balloon valvuloplasty. Review of the results of balloon valvuloplasty in these patients with mild stenosis showed that 59 patients from 11 studies underwent the procedure for a peak pulmonary valve gradient less than 50 mm Hg.” The peak-to-peak systolic pressure gradient across the pulmonary valve was reduced from 38 ? 6 mm Hg (mean + SD) to 20 ? 11 mm Hg (P < .Ol) immediately after valvuloplasty, as was the right ventricular peak systolic pressure (60 -+ 9 v 43 k 11 mm Hg P < .Ol). At fo,llow-up several months following balloon valvuloplasty, the pulmonary valve gradients (24 ? 12 mm Hg) and the right ventricular pressure (45 + 12 mm Hg) remained improved (P < .Ol) when compared with prevalvuloplasty values. These data indicate there was a statistically significant reduction in pulmonary valvar gradients even in patients with mild pulmonary stenosis. However, the mean residual right ventricular peak systolic pressure at follow-up was 75% of prevalvuloplasty measurements. The question to be asked is whether this modest reduction in the right ventricular pressure is
P. SYAMASUNDAR
RAO
worth the risk, morbidity, and expense associated with cardiac catheterization and balloon pulmonary valvuloplasty? The answer (my answer) is “no,” especially in view of a benign natural course of the disease process”h-jO; mild pulmonary stenosis remains mild on follow-up. Therefore, the advisability of balloon valvuloplasty for mild obstruction can be questioned. The recommendations” are to consider the indications for balloon valvuloplasty to be the same as those used for surgical valvotomy and that balloon dilatation should not be performed in patients with gradients less than 50 mm Hg. Because noninvasive Doppler estimates of pulmonary valve gradients are reasonably accurate,41-44 patients with mild stenosis can be followed, and once the Doppler estimate of the gradient is in excess of 50 mm Hg, they can undergo balloon valvuloplasty. Although there is some wisdom in using valve areas for setting criteria for intervention, gradients are adequate for the pulmonary valve provided cardiac indices are measured during prevalvuloplasty catheterization and are shown to be within the normal range. Some investigators4j suggested that balloon valvuloplasty should not be performed in severe stenosis if the peak systolic pressure in the right ventricle is approximately twice that in the left ventricle. Although their concern is understandable, balloon valvuloplasty can be performed safely (see Technique. Appendix 1) in such patients. There were sixteen patients of a total of 71 infants and children46 who had right ventricular pressures approximately twice that in the left ventricle in whom we were able to successfully perform balloon valvuloplasty. Some investigators consider dysplastic pulmonary valves as a relative contraindication for balloon valvuloplasty, 47*48but based on results of others49.s0 and our data,iO balloon valvuloplasty is the initial treatment of choice; perhaps, large balloons to produce balloon/annulus ratios of 1.4 to 1.5 should be used.]” Our experience’.” and that in the Registry’ indicate that the procedure is also successful in patients with Noonan’s syndrome. Patients whose pulmonary valves restenosed following a previous surgical pulmonary valvotomy also respond favorably to balloon pulmonary valvuloplasty. In conclusion, moderate to severe valvar pulmonic stenosis
CATHETER
THERAPY
OF PULMONARY
STENOSIS
121
(gradient 2 50 mm Hg) irrespective of previous surgical intervention and pulmonary valve dysplasia is an indication for percutaneous balloon pulmonary valvuloplasty. The technique of balloon valvuloplasty is described in Appendix 1. Acute Results
Since the description of balloon pulmonary valvuloplasty by Kan and associates,’ several pediatric cardiology centers across the world Most have used this technique. 2 ..1,45,48-50,53,55,5X,60-84 groups
of investigators,45.49,5~,5~,S5.58,60-~4 includ-
ave reported excellent immediate relief of pulmonic valve obstruction following balloon valvuloplasty. From our group, 73 infants and children, aged 2 days to 20 years (median, 5 years), underwent balloon dilatation of valvar pulmonic stenosis* during a 7 year 8 month period ending May 1991.46 Following valvuloplasty, the peak systolic pressure in the right ventricle decreased (108 rf: 41 (mean -+ SD) v 53 + 22 mm Hg, P < .OOl) as did the peak systolic gradient across the pulmonic valve (91 + 41 v 26 k 19 mm Hg, P < .OOl) (Fig 1). The pulmonary artery pressure (17 + 5 v 23 + 6 mm Hg, P < .OOl) increased. The cardiac index did not change (P > .l). Width of the jet of the contrast material through the pulmonary valve as visualized in the cineangiograms (Fig 2) increased. Less doming and much more “free” movement of the pulmonary valve 1eafletP occurred following the valvuloplasty in each case. Improvement of right ventricular function and a decrease in right-to-left atria1 shunting”’ also occurred. Though not studied by us, improvement in the function of the left ventricleXh is expected. Surgical intervention is avoided in all our cases. Most patients are discharged home within 24 to 48 hours following the procedure. ing
ours,2,3.7,13,15.?1,46
h
Follow- Up Results
Several investigators49J”Js,h5-C8*70,71,7.5 recatheterized 6 to 53 patients, 1 week to 18 months
*Balloon pulmonary valvuloplasty was performed at King Faisal Specialist Hospital and Research Center, Riyadh, Saudia Arabia (1983-1987) and at University of Wisconsin Hospital and Clinics, Madison, WI (1987-1991) and will be referred to as the Madison experience throughout the manuscript.
Fig 1. Bar graph showing acute results of balloon pulmonary valvuloplasty in 73 patients showing a significant (P < .OOl) decrease in the peak-to-peak systolic pressure gradient across the pulmonic valve and peak systolic pressures in the right ventricle. Also, note a significant (P < ,001) increase in the peak systolic pressure in the pulmonary artery.
(mean) following balloon valvuloplasty and reported significant residual gradients ( > 30 mm Hg) in 14% to 100% of patients (Table 1). We recatheterized 45 children 6 to 34 months (mean, 11.0 months) following balloon valvuloplasty. For the group of children in whom follow-up catheterization data were available, the peak systolic pressure gradient across the pulmonic valve (92 & 43 v 29 +- 23 mm Hg, P .: .OOl) and the peak systolic pressure in the right ventricle (109 f 41 v 56 + 22 mm Hg, P < .OOl) decreased immediately after balloon dilatation. The cardiac index (3.3 ? 0.9 1~3.2 -+ 0.7 L/mini ml, P > .l) remained unchanged. On followup, approximately 11 months later, systolic pressure gradient across the pulmonic valve (29 + 23 mm Hg, P < .OOl) remained improved when compared with the predilatation value (Fig 3). The cardiac index (3.5 * 0.8 L/minim’) did not significantly (P > .l) change. Despite improvement as a group, several children had significant residual gradients (Fig 4) across the pulmonic valve, hereafter referred to as restenosis. Nine out of 45 children that were restudied had pulmonary valve gradients in excess of 30 mm Hg. Six of these children underwent repeat balloon valvuloplasty with larger balloons (Fig 6) and the pulmonary valve gradients were reduced from 96 * 40 to 40 ? 22 mm Hg (P < .Ol). The other 3 children with residual gradients of 45, 50, and 60 mm Hg are being followed clinically. Repeat follow-up catheterization (in 4) or Doppler studies (in 4) were available in 8 children (24 months after the first
P. SYAMASUNDAR
RAO
Fig 2. Selected cineangiographic frames from a “sittingup” view (40” cranial and 15” left anterior oblique) of a right ventricular angiogram before (A) and 15 minutes (B) following balloon pulmonary valvuloplasty. The thin jet of passage of contrast across the pulmonic valve (arrows) in A has markedly increased (arrows) in E.
Doppler follow-up data are available, ie, a 14% recurrence rate. In the recently compiled Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry data,87 suboptimal longterm results, defined as the need for surgery or repeat balloon valvuloplasty or a pulmonary valve gradient in excess of 36 mm Hg, was noted in 89 of 433 (21%) patients who had a follow-up at a median interval of 31 months after balloon valvuloplasty. Thus, the Madison data compare favorably with the VACA Registry data from 17 institutions. Apart from pressure gradient relief, there are
balloon valvuloplasty) and the residual pulmonary valve gradients were 28 ? 12 mm Hg. The restenosis rate (9 of 45, 20%) in the Madison group, though high, is comparable with the 14% to 100% rate reported by other workers (Table 1). However, it should be noted that we initially recommended recatheterization 6 to 12 months following valvuloplasty, but more recently, routine postoperative catheterization is not recommended unless the Doppler estimate of the residual gradient is high. Therefore, it is concluded that restenosis occurred in 9 of 63 patients in whom catheterization and/or Table
1. Intermediate-Term
Follow-Up Number
Author
and Year
Kan et al, 1984
Patients Undergoing BPV
20
of
Catheterization Numberof Patients With Follow-Up 11
Results
of Balloon
Pulmonary
Valvuloplasty
MC?atl (Range). Months
7 (2-12)
Poor Result* on Follow-Up, No. (%I
Comments
2 (18)
The failure
2 (33) 7 (IOOH
value or after previous Brock Both patients underwent surgery Repeat BPV in one patient with 52 mm Hg
27 19
6 7
- (2-6) 12 (9-13)
Miller,
16
7
4 (3-6)
l(14)
23
12
5.5 (0.25-6)
6 (50)
gradient
Sullivan
et al, 1985 et al, 1986
32
Shrivastava et al, 1987 Rey et al, 1988
32 51
Fontes et al, 1988 Schmaltz et al, 1989
Rao,
1991
Abbreviation: *Poor result tThe *Poor
14 21 23
2 (14) 9 (43) 5 (22) 10 (23) 14 (26)$
100
44
273
53
12 (3-14) ll-
73
45
11 (6-34)
BPV, balloon pulmonaryvalvuloplasty. is defined as pulmonary valve gradient
pulmonary valve result is defined
10 (6-14) - (3-18) -(l-17)
in excess
9
with
reduction
BPV with excellent Repeat valvuloplasty
Repeat tory
with
dysplastic
to 34 mm Hg
results in four
patients
with
results
BPV in five patients results
with
satisfac-
Repeat BPV in 14 patients; successful In IO. remaining 4 with dysplastic valves required surgery
(20)
Repeat
of 30 mm Hg at follow-up.
gradient ranged between 31 and 52 mm Hg with a mean as gradient ~40 mm Hg.
was in patients
Two patients with gradients of 24 and 22 mm Hg at follow-up underwent repeat
good Khan
the Literature
Duration of Follow-Up
Tynan et al, 1985 Kveselis et al, 1985 1985
From
of 38 mm Hg.
BPV in 6 patients
with
good
results
CATHETER
THERAPY
OF PULMONARY
STENOSIS
123
16Or Mean
Post
+ SD N = 45
FU
acute and follow-up results of the Fig 3. Bar graph showing 45 unselected patients (from among 73 patients undergoing balloon valvuloplasty-Fig 2) who underwent cardiac catheterization 11 months (mean) following balloon pulmonary valvuloplasty. Note significant (P c 0.001) decrease in the peak systolic pressure gradient across the pulmonary valve immediately after the procedure that remained unchanged (f > .l) at follow-up; the later continues to be significantly (P < .OOl) lower than the prevalvuloplasty gradient. The gradients represented are valvar gradients without any regard to infundibular gradients.
other benefits. Right-to-left interatrial shunting that was present before valvuloplasty has completely disappeared in most patients.20 Right ventricular dysfunction and tricuspid insufficiency improved. Figures 5 and 6 illustrate improvement in cardiac size and tricuspid insufficiency following balloon valvuloplasty. W&4,7.15 and otherS52,66,72.78,87,88 have previ-
ously reported echo-Doppler follow-up studies after balloon valvuloplasty. Kveseli@ reported results of Doppler examination in 11 patients 15 -+ 19 months following valvuloplasty; calcu-
I
. cam
.
0 P,P BP”
Post BP”
FU
Repd BP”
Second FU
Fig 4. Sequential pulmonary valvar gradients are shown for each of the nine patients who had gradients in excess of 30 mm Hg at follow-up catheterization. Repeat balloon dilatation at the time of follow-up (FU) catheterization in six of these children produced decreases in the gradient in each patient. At a second follow-up study (catheterization or Doppler), the gradients remained low. Solid circles, gradients measured at cardiac catheterization; open circles, Doppler estimated peak instantaneous gradients.”
I
lated right ventricular outflow gradient was reduced from 86 +- 29 to 38 + 9 mm Hg immediately after valvuloplasty, which decreased, though, to an insignificant degree, to 33 & 7 mm Hg, at follow-up. Doppler evidence for pulmonary insufficiency was present in 8 of 11 patients. Similar improvement was noted in a subsequent publications8 involving 28 patients with successful valvuloplasty. Robertson et al,“2 while analyzing the morphology of the right ventricular outflow tract following balloon valvuloplasty, reported follow-up (10.2 + 5.6 months) Doppler studies in 18 patients. The calculated pulmonary valvar gradient having been reduced to 37 ? 23 from 72 2 31 mm Hg immediately following valvuloplasty, decreased further to 31 2 21 mm Hg at follow-up. Mullins et alT2 obtained continuous-wave Doppler flow measurements in 30 children (of 63 children who underwent balloon pulmonary valvuloplasty) at a mean of 13 months following valvuloplasty; the estimated residual gradient was 20 & 8 mm mEcho-Doppler follow-up studies in 63 children 3 to 36 months (1.5 ? 6 months) following valvuloplasty were available from the Madison group. Two D-derived, M-mode tracings of the right ventricle and left ventricle and pulsed- and continuous-wave Doppler flow velocity recordings from the right ventricular outflow tract and the main pulmonary artery were recorded, as previously reported,4,7+4Zinitially, at 3- to 6-month intervals, and subsequently, at 1Zmonth intervals. The pulmonary valvar gradient was calculated using a modified Bernoulli equation (gradient = 4 V22, where V2 is peak Doppler flow velocity in the main pulmonary artery). When the right ventricular outflow tract Doppler flow velocity (V,) was in excess of 1.0 m/s, Vr was incorporated into the Bernoulli equation [gradient = 4 (V22 - Vr2)]. The echo-Doppler results were analyzed separately for the group with good results (group I) and for the group with poor results (group 11). In the group of patients with good results, the right ventricular enddiastolic dimension decreased, but not significantly (P > .05), from 18.3 2 5.6 to 16.2 ? 5.3 mm immediately after valvuloplasty, which decreased further to 15.4 f 5.0 mm (P < .Ol) at the last available follow-up (Fig 7). The left ventricular end-diastolic dimension did not
124
P. SYAMASUNDAR
RAO
Fig 5. Posteroanterior view of a chest roentgenogram showing cardiomegaly (A) before balloon pulmonary valvuloplasty. The cardiomegaly has improved on a chest x-ray taken 1 year following balloon valvuloplasty (B).
change immediately following valvuloplasty (30.8 ‘-+ 8.3 v 29.6 + 7.8 mm, P > .l), but at follow-up, there was a significant increase (34.1 + 8.1 mm, P < -02) (Fig 8). The Doppler flow velocity in the main pulmonary artery decreased (P < .OOl) from 4.3 2 0.8 to 2.8 I 0.64 m/s immediately following valvuloplasty, which, on follow-up, was 2.4 2 0.6 m/s (P < .OOl) (Fig 9); when pressure gradients were calculated, these values respectively corresponded to 77 ? 29 (pre), 31 -+ 15 (post), and 24 ? 12 mm Hg (at follow-up). An example is shown in Fig 10. Doppler evidence for mild pulmonary insufficiency was present in 50 of 54 patients in whom data was available. Longitudinal, follow-up, Doppler flow velocities in the pulmonary artery are shown in Fig 11. These data show that there is rapid reduction of flow velocities immediately following valvuloplasty with further reduction at 6 months follow-up. Subsequently, there was minimal reduction, if any.
Fig 6. Posteroanterior views of the right ventricular (RV) cineangiogram before (A) and 1 year following (B) balloon pulmonary valvuloplasty. Note disappearance of tricuspid insufficiency at follow-up (B). The right ventricular cineangiograms correspond to A and B of Fig 7. C, catheter, PA, pulmonary artery; RA, right atrium.
By contrast, in the group of patients with poor results (group II), the right ventricular enddiastolic dimension (21.0 2 9.4 mm) did not change (P > .i) either immediately after valvuloplasty (21.0 +- 10.6 mm) or at follow-up (21.0 * 12.7 mm) (Fig 7). Similarly, left ventricular end-diastolic dimension (27.0 zt 6.7 mm) did not change (P > .l) immediately following (30.8 + 10.8 mm) or several months after valvuloplasty (26.1 f 5.6 mm) (Fig 8). Peak Doppler flow velocity in the pulmonary artery before valvuloplasty was 4.1 2 0.7 m/s, which remained essentially unchanged (P > .05) after valvuloplasty (3.5 rf 0.5) and on follow-up (4.0 * 0.6) (Fig 12). Doppler evidence for pulmonary insufficiency was present in two of the nine patients on follow-up. Six of the nine patients with poor results underwent repeat valvuloplasty; 7 to 12 months following repeat valvuloplasty the Doppler flow velocity decreased to 2.5 2 0.4 m/s (P < .OOl) (Fig 12). Based on these data, the intermediate-term
CATHETER
THERAPY
OF PULMONARY
STENOSIS
P’O.1
I I ” T
TI
T
PRE Group
I
Group
follow-up results appear encouraging and balloon valvuloplasty is recommended as a procedure of choice for treatment of isolated valvar pulmonic stenosis. Further refinement of the catheter technology and a better understanding of the use of balloon catheters with appropriate choices for specific situations may decrease or abolish the recurrence rate. Despite these good results, much longer-term (10 years) follow-up data are necessary to further confirm long-term effectiveness of balloon pulmonary valvuloplasty for relief of valvar pulmonic stenosis. Applicability To All Age Groups
Although balloon pulmonary valvuloplasty is used most frequently in children, it has
5 1
So
f
40
1
PbO.1 Mean
l
So
Iprg.l
7c-l
t
I
:
T
T
Group
I
Group
FU
PRE
IMM
FU
’
Fig 9. Peak Doppler flow velocities across the pulmonic valve before (PRE), immediately after (IMM) pulmonary valvuloplasty, and at follow-up (FU) are shown on the left-hand panel, whereas peak instantaneous Doppler-calculated gradients are shown in the right-hand panel for the group of patients with good results. Note significant (P c ,001) decreases in Doppler velocities and gradients immediately after valvuloplasty. There was further decrease (P < .Ol to c .02) at follow-up, presumably related to resolution of infundibular obstruction.
II
Fig 7. Right ventricular end-diastolic dimensions before (PRE) valvuloplasty, immediately after (IMM) valvuloplasty, and at follow-up (FU). Note that there was an insignificant (P > .05) decrease in RV size immediately after valvuloplasty, which diminished significantly (P c .Ol) at follow-up in the group I good-result patients, whereas no change (P > .l) was noted in the group II poor-result patients.
p~o.02
IMM
II
Fig 8. Similar to Fig 7 but left ventricular end-diastolic dimensions are shown. Note that there was no change immediately after valvuloplasty but a significant (P c ,021 increase was observed at follow-up in group I good-result patients. No change (P > .l) was noted in the group II with poor results.
also been used in neonatesh,“0,49.-5’.8y-y7 and in adults~65,68,71.74.98-106
Neonates. The experience with balloon pulmonary valvuloplasty in the neonate with critical pulmonary stenosis is limited and the series with largest numbers contain 5,90 8.49 and 1195,97 patients (Table 2). The procedure is more technically difficult but can be accomplished by the use of end-hole balloon-wedge catheters, small-sized, high-torque guide wires, low-profile balloon catheters, and progressive dilatation starting with small balloons. The pulmonary outflow tract occlusion during valvuloplasty is well tolerated if combined with continuous administration of prostaglandins to maintain ductal patency. Once the ductus is closed, progressive dilatation of the stenotic pulmonary valveg2 may be of benefit. The complication rateP and failure rates to accomplish balloon valvuloplasty are higher than those observed with older children. The overall result is also perhaps not as favorable as in children. Right ventricular hypoplasia, severe infundibular obstruction, pulmonary valve ring hypoplasia, and pulmonary valve dysplasia all tend to adversely affect the results of valvuloplasty in the neonate with critical pulmonary stenosis. Adults. Relief of pulmonary stenosis in adult patients has been accomplished by balloon valvuloplasty.65,6R,71.74.98-3*6 Because of the physical size of the pulmonary valve ring, many of them may require balloon valvuloplasty using two
flow Fig 10. Doppler pulmonary valvuloplasty. with permission.“)
velocities across Note significant
the pulmonic valve in a patient before, decrease in the velocity both immediately
balloons.101J02 However, as pointed out elsewhere,8J4 double-balloon technique is comparable to, but not superior to, single-balloon technique when equivalent balloon/annulus ratios are compared. Acute results (Table 3) of balloon valvuloplasty9*-lo6 are similar to those reported in children. Successful results have been documented even in the sixth and seventh decades of life.100J04J05 Based on our own experience with teenagers7,16 and that of others in adult patients ,98~101~103 infundibular obstruction following balloon valvuloplasty appears to be more common in older patients than in young patients. The reason for this is probably longstand-
on the day following, after valvuloplasty
and 8 months and at follow-up.
after balloon (Reprinted
ing right ventricular hypertension and consequent right ventricular hypertrophy in older patients. Follow-up results (Table 3) though documented in few studies102J0j do indicate persistent relief after a mean follow-up of 1 to 2 years. In summary, it appears that successful balloon valvuloplasty is feasible in all age groups. Complications Acute. Complications during and immediately after balloon pulmonary valvuloplasty have been remarkably minimal. Transient bradycardia, premature beats, and a decrease in systemic pressure during balloon inflation have been uniformly noted by all workers, particularly with valvar dilatations. These return rapidly back to normal following balloon deflation. Systemic hypotension may be minimal during balloon inflation in the presence of a patent foramen 5
PRE N=62
MM 3 N=SO N=27
Months
6 N=35
12 N=35
Following
16 N-15
24 N=12
30 N=6
36 N=5
42 N=4
Valvuloplasty
Fig 11. Peak Doppler flow velocities in the main pulmonary artery before (PRE) and immediately after (IMM) balloon valvuloplasty, and at follow-up are shown. N indicates the number of patients in whom the data were available at that particular interval. Note that a decrease in the flow velocity occurred immediately after valvuloplasty with further reduction at a E-month follow-up. There was minimal, if any, change subsequent to E-month follow-up. *indicates P < .Ol when compared with prevalvuloplasty values. tindicates P < .05 when compared with immediate postvalvuloplastyvalues. SD, standard deviation.
’
PRE
IMM
FU
FURI
PRE
MM
FU
FURI
Fig 12. Doppler flow velocity and instantaneous Doppler gradients across the pulmonic valve in the group II children with poor results. Note that there was no decrease in the gradient either immediately after (IMM) or at follow-up (FU). Repeat balloon valvuloplasty has resulted in decrease in gradients (P < .OOl). FURI, follow-up after reintervention.
CATHETER
THERAPY
Author
OF PULMONARY
STENOSIS
Table
of Balloon
2. Results
Number of Patients Undergoing BPV
and Year
Rey et al, 1988
127
Pulmonary
Valvuloplasty
Pulmonary Valve Gradient (mean ? SD),mm Hg Pre
8
107
+ 22
Post
FU
59 k 90
25 k 10
in Neonates
From
FU No/Duration
P00r Result No. (%I
Al-17
mo
the Literature
2 (25)
Comments Pressure nates
data were from 8 neoand 11 infants i 1 .O yr.
Repeat valvuloplasty neonates. Zeevi
et al. 1988
All Khan
5
et al,
123
4
t- 7*
59 + 8*
61 +45
6+
10
35+27
5lllmo
1 (20)
69 -c 47
318 mo
2 (66)
Pre-and peak Repeat dren
1989 Qureshi
et al, 1989
3
125,135*
15,ot
218 mo
13.16
post-pressures were RV systolic pressures. valvuloplasty in 2 chilreduced
et al, 1990
Ladusans
et al,
ll$
68 + 4
20 2 4
11s
(mean f SEM) 87 i 30
(mean + SEM) 33 s 28
-
0 (0)
11119mo
gradient
to 10
and 30 mm Hg. respectively. One patient died after unsuccessful tation.
Caspi
in both
-
attempt
at balloon
dila-
FU results were not given but stated to be not changed.
39 i 23
10122
mo
4 (40)
One patient died BPV, 4 patients
25 2 32
3114
mo
1 (33)
Repeat balloon valvuloplasty reduced gradient from 61 to 18
1990
7 days after required repeat
intervention. Rao et al, 1991
3
69 2 50
11 + 11
mm Hg. NOTE.
Single
case
Abbreviations: *Right ventricular
reports
and abstracts
are not included.
BPV, balloon pulmonary valvuloplasty; peak systolic pressures.
FU, follow-up;
RV, right
ventricular.
tlnfundibular *Attempts
gradient for balloon
was 100, which subsequently disappeared. valvuloplasty were made in 20 patients; the procedure
was accomplished
in 11 neonates.
OAttempts
for balloon
valvuloplasty
was accomplished
in 11 neonates.
Table
were
3. Results
Number of Patients Undergoing Author
Pepine
and Year
et al, 1982
made
in 15 patients;
of Balloon
the prodecure
Pulmonary
Valvuloplasty
BPV
Pre
Post
1
140 83,70 30
30,24 32
107 95
52 25
36
105 93 2 22
13 26 f 12
-
70 + 28 260
10 2 3 90 32% 14
Kan et al, 1984 Shuck et al, 1984
2 1
Khalilulah
1
in Adults
Pulmonary Value Gradient (mean 2 SD),mm Hg FU No/Duration
FU
42
38
l/IO
22,-
days
From
PCW FkSUlt* No. (O/o)
Comments
1 (100)
lnfundibular
-
Gradients higher
I/1/14days
2
the Literature
post, Gibbs
et al., 1985 et al., 1986
Cooke et al, 1987 Al Kasab et al, 1988 Mashru et al. 1988 Flugelman et al, 1988 Frawzy et al, 1988
1 1 21 3 1 18
105 2 30
and
FU. respectively) -
Only clinical No follow-up
90 11
14117
mo
5 (36)
113 wks lll6mo
follow-up
Double balloon No follow-up
in all patients. -
1 (100) 4 (36)
developed
after exercise were (69, 28, and 20, pre,
1 (100)
1.1 mo
17 2 5 26?
gradient -
Repeat
balloon
valvuloplasty
patients reduced the gradient from 59 and 52, repectively,
in 2 to
24 and 22 mm Hg. NOTE. Shrivastava et aP8 and Fontes et al” reported for adult patients. Abbreviations: BPV, balloon pulmonary valvuloplasty; *Poor
results
is defined
as a residential
pulmonaryvalvar
successful
balloon
valvuloplasty
in adults,
FU, follow-up. gradient
> 30 mm Hg at follow-up.
but the data were
not separately
given
128
ovale because of the right-to-left shunt across it, filling the left ventricle.106 Use of double balloons10r and of a trefoil or a bifoil balloon,b0-h3 to allow blood egress from the ventricle during balloon inflation and shorter periods (5 seconds) of inflation, 8~14have been advocated to reduce the systemic hypotension. After evaluation of each of these techniques, a short period of balloon inflation (5 seconds or less) appears most efficacious without compromising immediate or follow-up results.2i,23 Blood loss requiring transfusion has been reported in many studies. Complete right bundle branch block,90 transient or permanent complete heart block,5”.‘07 cerebrovascular accident,49 loss of consciousness,5’ cardiac arrest,‘08 convulsions,53 balloon rupture at high inflation tricuspid valve papillary muspressures, 49.64*70,109 cle rupture,“O pulmonary artery tears,“’ rightsided endocarditis,‘12 and severe infundibular obstruction requiring propranolol administration7J”J8,49,70.71and/or surgical intervention,70,rr3 though rare, have been reported. Some of these complications may be unavoidable. However, meticulous attention to the details of the technique, use of appropriate length of the balloon, avoidance of extremely high inflation pressures, and use of short inflation/deflation cycles may prevent or reduce the complications. Holter monitoring for 24 hours following balloon valvuloplasty6h showed premature ventricular contractions (grade 1, Lawn criteria) in one third of the 12 patients so studied. It is not clear from this studfe whether the premature beats were present before valvuloplasty and for how long after valvuloplasty the premature beats persisted. Transient prolongation of the QT, interval following balloon angioplasty/valvuloplasty1’4~1r5 may be a potential hazard for developing R-on-T phenomenon in children with ventricular ectopy. The Holler findingP of premature beats following valvuloplasty may have significance in the light of prolongation of the QT, interval.rr4 However, no patients from our series or many other studies have been known to develop ventricular arrhythmias, although two cases of sudden death from ventricular fibrillation shortly after balloon angioplasty of aortic coarctation’lhJr7 were reported. Whether these arrhythmias are related to QT, prolongation or not is
P. SYAMASUNDAR
RAO
not known. However, patient monitoring following balloon valvuloplasty/angioplasty is warranted.l14 Although multiple complications were listed, the VACA Registry reported only a 0.24% death rate and 0.35% major complication rate from the 822 balloon pulmonary valvuloplasty procedures from 26 member institutions” attesting to the safety of the procedure. Complication at follow-up. With regard to complications at intermediate-term follow-up, femoral venous occlusion, pulmonary valve insufficiency, and pulmonary valve restenosis have been noted. Anywhere between 10% to 29%‘J9J’” of femoral veins through which balloon valvuloplasty have been performed were noted to be occluded at follow-up. In the Madison series, 3 of 45 patients (7%) that we restudied following pulmonary valvuloplasty had a blocked femoral vein. It is the consensus that the femoral venous occlusion is more common in small infants.4y~hh~10” Auscultatory evidence for pulmonary valve insufficiency has not been thoroughly scrutinized. Doppler evidence for pulmonary insufhciency appears sensitive but was studied by only Rocchini and a few investigators. 7.52.66.72.78.88 BeekmatP reported pulmonary insufficiency in 31 of 37 (84%) patients, whereas Robertson et aP2 found mild pulmonary insufficiency in all 29 patients studied. When we reviewed this last from our group, 50 of 54 (93%) patients had Doppler-demonstrable pulmonary insufficiency. However, the pulmonary insufficiency is minimal as evidenced by lack of right ventricular volume overloading (normal-sized right ventricle and no paradoxical septal motion) in this group of patients as well as by equilibriumgated radionuclide angiograms reported by Tynan.S3 Although the long-term follow-up studies should be scrutinized for progressive right ventricular volume overloading, the current data suggest that the pulmonary insufficiency produced by balloon vaivuloplasty is unlikely to be problematic. Recurrence of valve stenosis following balloon pulmonary valvuloplasty has been reported by most investigators (Table I), but the reasons for the restenosis at intermediate-term follow-up has been studied only to a limited degree.‘“,S5.65-67.87 W e h ave systematically investigated the cause of recurrence of pulmonic
CATHETER
THERAPY
OF PULMONARY
129
STENOSIS
stenosis following balloon valvuloplasty.12J7 On the basis of results of 6- to 34-month follow-up catheterization data in 40 children, they were divided into group I with good results (pulmonary valve gradient of 30 mm Hg or less), 33 patients; and group II with poor results (gradient greater than 30 mm Hg), seven patients. Fourteen biographical, anatomic, physiological, and technical factors (Table 4) were examined by multivariate logistic regression analysis to identify factors associated with restenosis. The identified risk factors were (1) residual pulmonary valve gradient in excess of 30 mm Hg immediately following balloon valvuloplasty and (2) balloon-to-pulmonary valve annulus ratio less than 1.2. Dysplastic pulmonary valves did not seem to play a role in recurrence and this may have been due to the use of large balloons with dysplastic valves. The influence of these factors on restenosis is examined in Figs 13 and 14. The smaller ballooniannulus ratios are associated with a higher chance for recurrence as are the higher residual gradients immediately following balloon pulmonary valvuloplasty. The data suggested that a balloon/annulus ratio of less than 1.2 is the cause for pulmonary valve restenosis at intermediate-term follow-up, and such recurrences can be predicted in patients with immediate postvalvuloplasty pulmonary valve gradient in excess of 30 mm Hg. ThereTable
4. Variables
Regression Pulmonary
Examined
Analysis Value
by Multivariate
to Identify
Restenosis
Factors
Following
Logistic
Responsible Balloon
for
Valvuloplasty
Age at valvuloplasty Duration of follow-up Pulmonary Pulmonary
valve valve
Right ventricular Angiographic
dysplasia, severe ring hypoplasia
hypoplasia infundibular
peak systolic peak systolic
loplasty Right ventricular
infundibular
loplasty Pulmonary
peak
valve
Advances
and Publishing in Medicine
pressure
B/A
Ratio
1.2 or
BIA
Less
Rati io >1.2
Fig 13. Rates of recurrence of pulmonary valve stenosis after balloon valvuloplasty as it relates to balloon/annulus ratio are shown. Note that the rates of restenosis increase es the balloon/annulus ratio decreases. Percentages are marked within the bars and actual numbers are shown on the top of each bar.
fore, it is suggested that progressively larger balloons be used and reduce the valve gradient to less than 30 mm Hg.12J7J Pulmonary valve dysplasia and pulmonary valve annular hypoplasia may well play a significant role in the recurrence of pulmonary valve obstruction but did not seem to have an adverse effect in our study group, perhaps related to the narrow ranges of such abnormalities in our study group. Recent analysis of the VACA Registry data8’ on 433 patients followed up to a median interval of 31 months also identified balloon/annulus ratio and immediate postvalvuloplasty gradient 2 36 mm Hg as factors predicting a suboptimal follow-up result, very similar to our study.L2J7 In addition, the Registry data analysis identified dysplastic pulmonary valve morphology and age less than 2 years as factors predisposing to recurrence. I
before valvuloplasty gradient before valvugradient
pressure
annulus
reprinted Co., and
Ratio >l.O
“”
gradient
before
valvu-
immediately
ratio
Maximum pressure achieved in the balloon Number of balloon dilatations Total duration of balloon inflation Copyrighted Cardiology
B/A
or mild
pressure pressure
systolic
valve
Ratio
1.0 or Less
stenosis
Right ventricular Pulmonary valve
after valvuloplasty Balloon/pulmonary
B/A
with rhe permission of Clinical Inc., and/or the Foundation to:
Science.15
Pulmonary Gradient
Valve 530
Fig 14. Similar to balloon valvuloplasty ents are used instead rate of recurrence at Hg immediately after
mmHg
Pulmonary Gradient
Valve ~30 mmHg
Fig 13 except that the immediate postpeak-to-peak pulmonary valve gradiof balloon/annulus ratios. Note a higher follow-up when the gradient is >30 mm valvuloplasty.
130
P. SYAMASUNDAR
Table
5. Summary
Patients
With
Author,
of Results
Pulmonary
of Balloon
Valve
No of Patients With DPV
Year
Valvuloplasty
Dysplasia
From
Immediate Success 1%)
in
the Literature Follow-Up Success (%)
Kan et al, 1984 Tynan et al, 1985
1 3
0 (0) 0 (0)
0 K’l
Miller, 1986 Sullivan, et al, 1986
1 2
0 (0) 1 (501
0 (0)
Rocchini 1986
& Beekman, 7
0 (0)
Musewe Di Sessa
et al, 1987 et al, 1987
5 3
1
Rey et al, 1988 Marantz et al, 1988
4 4
Rao et al, 1988 Ballerini et al, 1990
13 9
Total
52
Abbreviation: *Patients calculation
DPV, dysplastic without of percent
follow-up
0 (0)
120)
0 (0) 3 (75)
3 (75)
3 (75) 9 (69)
2 (50) 10 (77)
2 122)
3 (331 22 (47)X
19 (37) pulmonary
were
3 (43) 1 (201
excluded
valves. for the purpose
of
success.
Other Issues L$splastic pulmonary valve. Dysplastic pulmonary valves have been implicated as a cause of failure following balloon pulmonary valvuloMore recently, detailed replasty. 49~s3~55~65-67~88 ports of balloon valvuloplasty in patients with dysplastic pulmonary valves47,48suggested that poor results may be expected with dysplastic pulmonary valves. A summary of experience reported in the literature is tabulated in Table 5. The Madison experience with dysplastic pulmonary valves is contrary to that reported in these articles. Therefore, we previously reviewedI the results of balloon valvuloplasty in 13 patients with dysplastic pulmonary valves from our total experience at that time with 56
RAO
patients to assess outcome in this subgroup. These results were compared with valvuloplasty results of 43 nondysplastic pulmonary valves.“’ Dysplasia of the pulmonary valve was assessed based on the criteria outlined by Jeffery, Koretzky, and their associates.“K.l’” When all criteria, namely (1) angiographic appearance of nodular and uneven thickening and poor doming of the valve leaflets (Fig 15), (2) valve ring hypoplasia (less than mean value for the given body surface area as defined by Rowlatt),‘“l and (3) no poststenotic dilatation, were present, the pulmonary valve was considered dysplastic. When valve leaflets appeared dysplastic without the presence of one or both of the other criteria. the valve was considered mildly dysplastic. A total of 13 dysplastic pulmonary valves were identified; 7 were severely dyspIastic and 6 were mildly dysplastic. Balloon valvuloplasty in 13 patients, aged 6 days to 12 years (median 1 year), with dysplastic pulmonary valves reduced the pulmonary valve gradient from 77.2 & 44.2 to 26.8 +- 17.0 mm Hg (P < .OOl), which remained improved (34.9 +34.6 mm Hg, P < .02) at 6- to 19-month (mean. 10 months) follow-up (Table 6). The results of individual patients are depicted in Fig 16. Valvuloplasty in 43 patients without dysplastic pulmonary valves reduced the valve gradient from 94.3 2 41.0 to 31.1 2 22.4 mm Hg (P < .OOl) immediately following the procedure, which at 6- to 34-month follow-up in 23 patients was 29.2 t 33.5 mm Hg (P < .OOl) (Table 6). The pulmonary valvar gradients (77.2 -+ 44.2 1’94.3 + 41.0 mm Hg) before valvuloplasty. residual
Fig 15. Selected frames from right ventricular (RV) cineangiograms of patients without (A) and with (B) dysplastic pulmonary valves. (A) Thickened and domed pulmonary valve leaflets are noted. Note poststenotic dilatation of the pulmonary artery (PA). (6) Pulmonary valve leaflets are markedly and unevenly thickened without doming. There was no jet formation and no poststenotic dilatation of the PA. The pulmonary valve ring is small when compared with norms described Rowlatt et al.‘*O (Reprinted with permission.lO)
CATHETER
THERAPY
Table
OF PULMONARY
6. Comparison
Dysplastic
of the Group
Pulmonary valve dient prevalvulo-
dient
131
of Patients
Pulmonry Valves With the Group Pulmonary Valve Dysplasia Dysplasia (mean + SD)
plasty, Pulmonary
STENOSIS
With With
No Dysplasia (mean k SD)
No
P Value
gra-
mm Hg valve gra-
77.2
+ 44.2
94.3
* 41 .o
>.I
26.8
2 17.0*
31.1
+ 22.4*
>.l
-c 34.6t
29.2
k 33.5*
>.l
immediately
after valvuloplasty, mm Hg Pulmonary valve gradient at follow-up, mm Hg
34.9
*P < .OOl when
compared
tP < .02 when Reprinted with
compared permission.‘0
with with
prevalvuloplasty prevalvuloplasty
gradient. gradient.
pulmonary valvar gradient (26.8 + 17.0 v 31.1 2 22.4 mm Hg) immediately after valvuloplasty, and residual gradient (34.9 + 34.6 v 29.2 f 33.5 mm Hg) at follow-up catheterization were similar (P > .l) in both groups (Table 6). However, the ballooniannulus ratio used in dysplastic pulmonary valve patients (1.3 2 0.25) was slightly higher than that used in nondysplastic pulmonary valve patients (1.2 + 0.24), although this difference did not attain statistical significance (P > .l). Two of the 13 dysplastic pulmonary valve patients (Fig 16) and three of the 23 nondysplastic pulmonary valve patients required repeat valvuloplasty (P > .l) at fol0) 200 r
I
Pre SPV
Post SPV
FU
Repeat SPV
Second FU
Fig 16. Peak-to-peak pulmonary valve systolic pressure gradients in 13 patients with dysplastic pulmonary valves are shown. Note significant decrease in pressure gradient immadiately after balloon pulmonary valvuloplasty (BPV) in all patients. Gradient in excess of 30 mm Hg was present in four patients. At follow-up (FU) study, gradients remained low or decreased further in 10 patients (solid lines), whereas gradient increased in three patients (broken lines). Two of these children underwent repeat valvuloplasty with larger balloons at follow-up study with resultant decrease in gradients. One of these children underwent a second follow-up study and the residual gradient was low. (Reprinted with permission.9
low-up catheterization. Residual pulmonary valvar gradients in excess of 30 mm Hg at follow-up were present in 3 of the 13 and 4 of the 23 (P > .l) patients, respectively, with and without dysplastic valves. When all valvuloplasties were divided into those with good results (gradient I 30 mm Hg at follow-up), 29 patients, and those with poor results (gradient > 30 mm Hg at follow-up), 7 patients, the prevalence of dysplastic pulmonary valves, respectively, in these two groups was ten and three and was similar (Z’ > .l). In ten patients with dysplastic pulmonary valves with good results, the ballooniannulus ratio (1.37 + 0.22) used for valvuloplasty was larger (P < .Ol) than that (1.04 2 0.17) used in three patients with poor results. These data suggest that (1) the results of balloon valvuloplasty in patients with dysplastic valves are comparable to those without, (2) the dysplastic valves were not responsible for recurrence of valve stenosis, and (3) use of large balloons in patients with dysplastic valves may have reduced the chance for recurrence.1o Marantz et a150 compared immediate and follow-up results of balloon valvuloplasty in four patients with dysplastic pulmonary valves with those of 32 patients without dysplastic valves and concluded that significant palliation or relief of gradient occurred following valvuloplasty and suggested that dysplastic pulmonary valves should not be excluded from an attempt at balloon valvuloplasty. In the VACA Registry study,s7 examining the causes of suboptimal follow-up result, dysplastic valve morphology was identified as one of the factors predisposing to poor outcome. However, this group included complex pulmonary stenosis (for example, tetralogy of Fallot). The reason for the discrepancy between different studies10~47~48~50~87 in the results of valvuloplasty in patients with dysplastic pulmonary valves is not clear; it may be related to interpretation of clinical and angiographic data in labeling a given patient as having dysplastic pulmonary valves, it may be related to variable degrees of pulmonary valve dysplasia,47,121.12’ or presence of commissural fusion mixed with dysplasia.47.4x,121It is generally considered that splitting of commissural fusion123 is one of the major mechanisms of relief of valvar stenosis by bal-
P. SYAMASUNDAR
132
loon dilatation. Therefore, it is somewhat surprising that some patients with dysplastic valves would have good results. However, variability of the extent of dysplasia and dysplasia mixed with commissural fusion47.48.119,121,122 can to some extent explain these results. Musewe et al47 suggested that if echocardiographic features of commissural fusion are present, catheterization and angiography should be performed to confirm commissural fusion, and if so, balloon valvuloplasty should be performed. We agree with this approach. However, based on these resultslo and those observed by Marantz et aLso we would recommend balloon valvuloplasty for relief of pulmonary valve obstruction even with angiographic features of pulmonary valve dysplasia. Also, it seems reasonable to use larger balloons than is recommended for nondysplastic pulmonary valves; we personally tend to use balloons large enough to produce balloon/ annulus ratios of 1.4 to 1.5 and tend to avoid ratios in excess of 1.5 for fear of damage to the right ventricular outflow tract.59 Injimdibular obstruction. Several reports identify infundibular obstruction as a complicating feature immediately following balloon valvu~~p~~~ty~2,3,7,49,52,55,58.70-72.98,103,1~,113,124,125
This
prob-
lem was further studied in order to define the prevalence and significance of infundibular obstruction in patients undergoing balloon valvuloplasty for valvar pulmonic stenosis;16 we used the data of 62 children who had undergone balloon angioplasty during a 55-month period ending May 1988. Thirteen of the 62 (21%) children had infundibular pressure gradients before valvuloplasty; these ranged between 10 to 137 mm Hg (49 -+ 42 mm Hg). Following valvuloplasty, infundibular gradients disappeared in 5 patients (Fig 17). The infundibular gradient in the remaining 8 patients were 33 & 26 mm Hg with a range of 5 to 80 mm Hg. In six of these eight patients, the infundibular gradients diminished when compared with prevalvuloplasty gradients. In one child, the gradient remained unchanged at 20 mm Hg, and in the final patient, the infundibular gradient increased from 40 to 45 mm Hg. In five additional patients without infundibular gradients but with angiographic infundibular narrowing, an infundibular gradient appeared after valvuloplasty; new infundib-
100 m =
SO
E _ 60 E $
40
E a
20
RAO
-
-
0 I
Before
Immediately After
Follow-up
Fig 17. Sequential infundibular gradients before and immediately after balloon pulmonary valvuloplasty and at follow-up are shown. Thirteen children had initial gradients, 5 disappeared following valvuloplasty. New gradients appeared in 5 other patients. The gradients either disappeared or improved at follow-up. (Reprinted with permission.16)
ular gradients were 15,30,34,50, and 69 mm Hg (40 & 21 mm Hg) (Fig 17). Thus, 18 of 62 (29%) patients had infundibular gradients before or immediately after valvuloplasty. Examples of severe infundibular reaction demonstrated by Doppler echocardiography and cineangiography are shown in Figs 18 and 19. One child received propranolol before valvuloplasty.18 Two other children, with what was thought to be successful balloon valvuloplasty, developed systemic-level pressures in the right ventricle because of severe infundibular reaction. Propranolol, 0.1 mg/kg, was slowly administered intravenously with decrease in the right ventricular pressures and infundibular gradients. These three and three other patients with infundibular stenosis were prescribed oral propranolol, 2 to 3 mg/kg/d in three to four divided doses, for approximately 3 months. None of the Madison group required surgical infundibular resection. Out of the total of 13 patients with infundibular gradients at the end of balloon valvuloplasty, the gradients disappeared at follow-up in 7 patients. No follow-up data was available in one child. In the remaining five patients with persistent infundibular gradients at follow-up, the gradients were low, range 10 to 47 mm Hg (mean, 29 mm Hg); in each patient, the gradient at follow-up was lower when compared with the immediate postvalvuloplasty gradient (Fig 17). The influence of severity of pulmonary valve obstruction and age of the patient on the development of infundibular obstruction was
Fig 18. following immediately follow-up, sion.7B)
Doppler flow velocity recordings from the main pulmonary artery before (left), and 1 day (center) and 10 months (right) balloon pulmonary valvuloplasty are shown. Note that there is no significant decrease in the peak flow velocity after valvuloplasty, but there is a characteristic triangular pattern, indicative of infundibular obstruction. At lo-month the flow velocity markedly diminished, suggestive of resolution of infundibular obstruction. (Reprinted with permis-
examined. The patients with infundibular obstruction (n = 18) had higher (P < .Ol) pulmonary valve gradients (119 2 51 mm Hg) than those (n = 44) without infundibular gradients (83 + 35 mm Hg). When the prevalence of infundibular obstruction was scrutinized (Table 7) patients with higher degrees of obstruction had a greater prevalence of infundibular stenosis. The age distribution of patients with and without infundibular gradients (9.8 + 7.1 v 8.2 ? 6.4 years) was similar (P > .l). However, the prevalence of an infundibular gradient was higher (P < .Ol) in older patients than in younger patients (Table 7). Several authors reported either persistence of right ventricular infundibular gradients or appearance of such gradients following balloon pu~monaryva~vu~op~asty~2.7.49.52,55,58.70.76.98,103,106.
113.
124~125 When such infundibular obstruction was severe, propranolol was administered by several groups of workers7~49,70.103J24 with variable re-
sults. Infundibular resection by surgery was required in three patients.70J’3JZs In a few studies with follow-up catheterization, the infundibular obstruction improved.7,49Js,58,9~~1Z4 The absence of a pressure gradient across an angiographically narrow right ventricular infundibulum in the presence of a more severe distal obstruction (valve stenosis) is well known126-128;this atypical behavior of multiple obstructions may be due to “forced vibration” with greater energy transfer into the cardiovascular segment upstream to the proximal obstruction than into the segment upstream to the distal obstruction.127J28 The elastic and pulsatile characteristics of the cardiovascular system are important for expressing this property.117,‘2x Once the valvar (distal) gradient was relieved, the infundibular (proximal) gradient appeared. Infundibular gradients immediately following valvuloplasty appear to be related to infundibular hyperreactivity and if severe (producing near
P. SYAMASUNDAR
134
Table
7. Relationship Between Severity Stenosis and Age With the Prevalence
of Pulmonary of lnfundibular
Valvar
Gradients No. of Patients in the Specified Group Pulmonary valve gradient 2 100 mm Hg
No. With lnfundibulat Gradients
21
9
Pulmonaryvalve gradient < 100 mm Hg
41
9
Pulmonary valve gradient 2 80 mm Hg
32
12
Pulmonary valve gradient < 80 mm Hg
30
Age Age
40 22
6 14
2 5 Years < 5 Years
*Chi-square Reprinted
with
4
P
VsllJe
< .Ol
< .Ol
< .Ol
permission.16
systemic pressure in the right ventricle), may need treatment with propranolol. We, indeed, observed significant improvement in the gradient following intravenous propranolol. This response is similar to that observed in patients with surgical pulmonary valvotomy.‘29 Although all Madison patients were managed without surgical resection of the infundibular obstruction, an occasional patient may require infundibular resection.70J13 Oral propranolol therapy may be required in some patients with significant infundibular obstruction; patients with an infundibular gradient in excess of 50 mm Hg, as suggested by Fontes et al,124 may be candidates for such therapy. The infundibular obstruction is expected to regress with time as has been observed following surgical pulmonary valvotvalvuloplasty.3.7,l",~s.Y~.1~4 OmY130-134 and balloon Whether propranolol has any effect in enhancing regression of infundibular obstruction cannot be answered by this study. Al Kasab and associatesio3 observed that five patients receiving propranolol before balloon dilatation developed insignificant infundibular gradients (12 + 4 mm Hg) following valvuloplasty, whereas six other patients not receiving propranolol developed more severe infundibular gradients (45 2 27 mm Hg). The latter gradient diminished (9 + 4 mm Hg) following propranolol. Although these authors did not recommend routine use of propranolol therapy before valvuloplasty, they implied the potential use of P-blockade. At this time, there is no
RAO
evidence to advocate routine use of p-blocking agents before valvuloplasty. Based on the Madison experience and that reported in the literature, the following considerations might help in the management of infundibular obstruction in patients with pulmanic stenosis following balloon valvuloplasty.‘” 1. Consider the possibility of development of infundibular obstruction after valvuloplasty in all patients with severe valvar pulmonic stenosis. 2. Perform careful pressure pullback recordings across the pulmonic valve and right ventricular outflow tract both before and 15 minutes following balloon pulmonary valvuloplasty. 3. Right ventricular cineangiograms should be performed and scrutinized for infundibular obstruction both before and 15 minutes following valvuloplasty. 4. Use adequate-sized balloon(s) so as to have a balloon/annulus ratio of 1.2 to 1.4 so that adequate relief of valvar obstruction occurs, which in turn, encourages resolution of infundibular obstruction. 5. Balloons that produce balloon/annulus ratios in excess of 1.5 should be avoided for fear of damage to right ventricular outflow tract muscle and precipitating the infundibular reaction. 6. If angiographic and pressure data suggest significant residual infundibular obstruction, P-blocking drug therapy may be necessary; it may be given if the residual gradient is in excess of 50 mm Hg. 7. If follow-up echo-Doppler or catheterization and angiographic studies performed 6 months to 1 year after balloon valvuloplasty show residual infundibular gradients 2 50 mm Hg, then consideration for surgical resection of the infundibular muscle should be given. If there is significant residual valvar obstruction, repeat balloon valvuloplasty with an adequatesized balloon(s) would be our therapeutic choice. With this approach, surgical resection of infundibular obstruction can be avoided in most, if not all, cases. In summary, infundibular gradients in association with balloon pulmonary valvuloplasty were documented in 29% (18 of 62) of patients. The prevalence of such gradients appears to be more frequent with increasing age and severity of valve stenosis. Some of these children may
CATHETER
THERAPY
OF PULMONARY
135
STENOSIS
develop systemic or suprasystemic pressures in the right ventricle because of hyperreactivity of the right ventricular infundibulum and may need P-blockade. The infundibular stenosis does regress to a great degree at follow-up. The potential for development of an infundibular gradient after balloon valvuloplasty should not deter physicians from the use of this technique for the treatment of valvar pulmonic stenosis. Conclusions Balloon pulmonary valvuloplasty has been used successfully over the last decade for the relief of moderate to severe valvar pulmonic stenosis in neonates, infants, children, and adults. Both immediate and intermediate-term follow-up results have been well documented by cardiac catheterization and Doppler studies. The results of balloon valvuloplasty are either comparable to or better than those reported with surgical valvuloplasty. Complications of the procedure have been minimal. The causes of restenosis have been identified, and appropriate modifications in the technique, particularly use of ballooniannulus ratio of 1.2 to 1.4, should produce better results than previously documented. Additional refinement of the catheters and technique may further reduce the complication rate and prevalence of restenosis. The indications for balloon valvuloplasty have not been clearly defined but should probably be similar to those used for surgical valvotomy; only patients with moderate to severe valvar pulmonic stenosis are candidates for balloon valvuloplasty. Previous surgery, pulmonary valve dysplasia, and Noonan syndrome are not contraindications for balloon valvuloplasty. lnfundibular reaction may be present in older patients and in patients with severe obstruction and can most often be managed with adequate valvuloplasty and p-blocking drugs with rare need for surgery. Miniaturization of the balloon/catheter systems, further refinement of the procedure, and meticulous attention to details of the technique may further reduce the complication rate and increase safety. Documentation of the favorable results at 5- to IO-year follow-up is necessary. Transcatheter techniques are excellent alterna-
tives to open or closed heart surgery in most, if not all, patients with pulmonary stenosis. SUPRAVALVAR
PULMONIC
STENOSIS
Stenosis of the main pulmonary artery may occur as an isolated anomaly or may be a component of other right ventricular outflow obstructive lesions such as valvar pulmonic stenosis and tetralogy of Fallot. It may also occur secondary to rubella syndrome. Supravalvar pulmonic stenosis may also develop at the site of anastomosis in the neopulmonary artery following an arterial switch procedure for transposition of the great arteries or it may be a residua after removal of a previous pulmonary artery band. There is only a limited experience with balloon dilatation of supravalvar pulmonary artery stenotic lesions.21,‘3.5-‘38 The indications for balloon angioplasty of these lesions should probably be similar to those recommended for valvar pulmonic stenosis”; moderate to severe peak-to-peak systolic pressure gradient (2 50 mm Hg) across the narrowed area in the face of normal cardiac index. Although there are no definitive guidelines, the size of the balloon should be at least two times the diameter of the narrowest site of obstruction. To the best of my knowledge, there is a single report of dilatation of native supravalvar pulmonary artery stenosis138 other than that used for cyanotic heart defects, discussed later in this review. Romero and his colleaguesl?” balloondilated discrete, “native” supravalvar pulmonary stenosis in seven children; they reduced peak systolic pressure gradients from 85 t 43 mm Hg to 27 5 17 mm Hg, P < .Ol. Follow-up studies at a mean of 3 years showed a residual gradient of 28 +- 12 mm Hg. They concluded that the discrete membranous or fibrous supravalvar obstructions can be effectively treated by balloon dilatation. We have attempted balloon dilatation in three children, ages 4, 6, and 19 years and reduced the gradients across the supravalvar stenosis; in two there were excellent results, but in the third, the gradient reduction was minimal. Two of these children manifested supravalvar pulmonary stenosis 4 and 15 years following surgical pulmonary valvotomy, respectively, and it is not clear whether the supravalvar stenosis
136
was native or developed secondary to surgery. The third child exhibited pulmonary artery narrowing 1 year following an arterial switch procedure for transposition of the great arteries. There was angiographic (Fig 20) and pressure gradient (Fig 21) relief in this child.*’ No follow-up data are available in these children. Schranz et al135 successfully balloon-dilated supravalvar pulmonary stenosis in a single patient who developed it following an arterial switch procedure. Zeevi and associates’36 attempted balloon angioplasty of postarterial switch supravalvar stenosis in five children and produced 1% to 75% gradient reduction; their assessment was that only one patient had a successful result with reduction of the peak-topeak systolic pressure gradient from 79 mm Hg to 20 mm Hg. Of the four patients with poor results, three underwent surgical relief 0 to 6 months after angioplasty. Saxena et a1i3’ attempted eight balloon dilatations in five chil-
P. SYAMASUNDAR
RAO
dren who developed supravalvar pulmonary stenosis following arterial switch procedures for transposition of the great arteries. In none of these dilatations was there any improvement in the pressure gradient across the area of obstruction nor was there any significant angiographic change. 13’ Based on the limited experience thus far documented,“J35-i37 it appears that discrete narrowing at the suture lines in the neopulmonary artery is likely to be relieved by balloon dilatation, whereas diffuse narrowings secondary to anteroposterior flattening13h or shrinkage and retraction of the pericardial patch’“’ used in the enlargement of neopulmonary artery are unlikely to respond to balloon angioplasty. Balloon dilatation was attempted in two patients with residual supravalvar pulmonary stenosis following removal of a previously placed pulmonary artery band.‘j6 The peak-to-peak pressure gradients were reduced from 60 and 65 mm Hg to 38 and 35 mm Hg, respectively. The percent reduction of the gradient was 37 and 42, respectively, and the data were interpreted as partially successful balloon dilatation.‘3h In summary, supravalvar pulmonary stenosis that develops following previous surgery can be relieved by balloon dilatation if it is a discrete narrowing. Balloon angioplasty should probably not be attempted if the obstruction is diffuse.4” There are limited data for native supravalvar pulmonic stenosis. PULMONARY STENOSIS WITH ATRIAL RIGHT-TO-LEFT SHUNT
This group of patients has very severe pulmonary stenosis with a resultant increase in right ventricular and atria1 pressures with consequent right-to-left shunting either across a patent foramen ovale or an atria1 septal defect.
Fig 20. Cine frames from lateral views of pulmonary artery cineangiograms showing supravalvar pulmonary stenosis (arrow) following arterial switch procedure (A) which improved markedly following angioplasty (B). (Reprinted with permission.zl)
Indications Any patient with severe enough pulmonary valve obstruction to produce right-to-left atria1 shunting and arterial desaturation is a candidate for relief of the pulmonary valve stenosis. No age or weight (size) are contraindications. It is important to relieve the pulmonary valve obstruction before deterioration of right ventricular function develops. The technique of balloon dilatation is described in Appendix 2.
CATHETER
THERAPY
OF PULMON
IARY
STENOSIS
137
Fig 21. Pressure pullback tracings across the supravalvar pulmonary stenosis showing significant pressure gradient (A) which diminished markedly following balloon angioplasty (6). Aortic pressure is also shown in 6. Ao, aorta; DPA, distal pulmonary artery; PPA, proximal pulmonary artery. (Reprinted with permission.zl)
Results Immediate results. Although some of the investigators, as listed elsewhere,46 may have mentioned patients with right-to-left shunt, none have grouped the patients in a manner similar to the grouping in this review. From our study group, we had 12 patients, aged 3 days to 11.5 years (median, 8 months), who underwent balloon pulmonary valvuloplasty.20 All had severe valvar pulmonic stenosis with intact ventricular septum and interatrial right-to-left shunting. The right ventricle was hypoplastic in 3 infants; severe infundibular stenosis was present either before or immediately after balloon angioplasty in 5 children, in a manner described elsewhere’$ poor right ventricular function was evident in 2 children; and Ebstein’s anomaly of the tricuspid valve was present in 1 infant. The right ventricular peak systolic pressure was above that in the left ventricle in 9 children and pressures were similar in both ventricles in the remaining 3. There
was a varying level of hypoxemia with a mean arterial oxygen saturation of 83 2 8% (mean 2 SD) with a range of 64% to 91%. The arterial desaturation is secondary to interatrial right-toleft shunting in all cases. Following balloon pulmonary valvuloplasty, the arterial oxygen saturation increased from 83 ? 8% to 94 2 5% (P < 0.001); in only 1 child was the oxygen saturation less than 91% after valvuloplasty. The pulmonary blood flow index (1.9 + 0.5 L/min/m2 v 2.8 ? 0.6 L/min/m2, P < .OOl), pulmonary-to-systemic flow ratio (Qp: Qs)(0.7 f. 0.1~1.0 + 0.2,P < .OOl),andpulmonary artery pressure (15 + 6 mm Hg v 27 & 9 mm Hg, P < .Ol) increased after valvuloplasty. Peak systolic pressure gradients across the pulmonary valve decreased (P < .OOl) from 105 & 48 mm Hg to 25 + 18 mm Hg. Infundibular pressure gradients were recorded before valvuloplasty in 2 children; these were 20 and 130 mm Hg. These gradients changed, respectively, to 27 and 30 mm Hg after balloon valvuloplasty.
P. SYAMASUNDAR
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lnfundibular gradients that were not present before valvuloplasty appeared in 2 children; these were 30 and 11.5mm Hg. Right ventricular cineangiography showed a greater movement of the leaflets of the pulmonary valve and a wider jet of contrast material passing across the pulmonary valve when compared with prevalvuioplasty cineangiograms. A hyperactive infundibular region was observed before and/or after valvuloplasty in 5 children, including the 4 in whom pressure gradients were recorded. The size of the right ventricle increased dramatically in a 7-day-old infant with critical pulmonary stenosis and hypoplastic right ventricle.h The size of the right ventricle decreased markedly in one child with associated Ebstein’s anomaly of the tricuspid valve. All but the two neonates were discharged home on the morning following balloon pulmonary valvuloplasty. The 2 neonates (3 and 7 days old), who were on ventilators at the time of valvuloplasty, were discharged home within 1 week after valvuloplasty. No complications other than an episode of supraventricular tachycardia in 1 neonate (which resolved spontaneously) were encountered. Follow-up results. Clinical and echo-Doppler follow-up data are available in 11 children, 1 to 31 months (mean, 12 months) following balloon dilatation, and cardiac catheterization was performed in 7 children, 6 to 18 months (11 2 4 months) after valvuloplasty. Arterial oxygen saturation (94 ? 6%) pulmonary blood flow (3.5 ? 0.9 L/minlm2), and Qp:Qs (1.0 -+ 0.1) remain improved (P < .Ol to .OOl) when compared with prevalvuloplasty values, but essentially unchanged (P > .l) when compared with immediate postvalvuloplasty values (Table 8). The pulmonary valvar gradient (33 & 33 mm Hg) continues to be lower (P < .OOl) than that Table
8. Results
of Balloon
Pulmonary
PA pressure, Pulmonary Hemoglobin, PA Doppler
mm Hg valve gradient, 9% flow velocities,
83 k 8
Right-to-Left P
Value’
Shunt
Group
1 to 31 Months After BPV (N = 10)
Value’ -. .Ol
P
94 t 5
i ,001
94 t 6
*. ,001
1.0 k 0.1
. .OOl
1.9 f 0.5
2.8 t
0.6
*: ,001
3.5 k 0.9
'. .OOl
15 k 6
27 t
9
‘. .Ol
17i
6
L ,001
33 i
33
105 15.4
m/s
Both the immediate and intermediate-term follow-up results are good with relief of right ventricular hypertension and systemic arterial hypoxemia. The group with intact ventricular septum and interatrial right-to-left shunting behaved in a manner similar to that observed with isolated pulmonary valve stenosis.“,7,‘T Despite restenosis of the pulmonary valve in two children, requiring repeat balloon dilatation, overall results are gratifying. Persistent hypoxemia was observed in only one child with a hypoplastic right ventricle and severe residual
1.0 + 0.16
0.7
mm Hg
Comments
Immediately After EIPV (N = 12)
(N = 12)
Arterial O2 sat, % Qp:Qs OP. L/minlmz
before valvuloplasty, but unchanged (P > .I) when compared with the immediate postvalvuloplasty gradient. Infundibular gradients disappeared in 2 children, decreased further in 1 child, and a significant residual (50 mm Hg) was present in the remaining child. Despite improvement as a group, 2 children had significant residual pulmonary valvar gradients, and repeat balloon pulmonary valvuloplasty was performed at the follow-up catheterization with reduction of gradients from 94 and 61 mm Hg to 26 and 18 mm Hg, respectively. None required surgical intervention and 2 children remain on B-blocking agents. Doppler studies (performed in a manner similar to that described elsewher+‘) at the last follow-up examination showed a mean Doppler flow velocity of 2.6 + 0.7 m/s across the pulmonary valve, which had been 4.9 ? 0.9 m/s before valvuloplasty (Table 8).“” Calculated instantaneous pressure gradients (26 rfr 10 mm Hg) were lower (P < .OOl) than those before valvuloplasty (100 t 36 mm Hg). No complications were observed at the follow-up catheter and clinical evaluation.
Valvuloplasty-Atrial
Before BPV
RAO
r 0.1
+48
25518
5 2.8
12.1
4.9 + 0.9
Abbreviations: BPV, balloon pulmonary valvuloplasty; Qp:Qs, pulmonary-to-systemic blood flow ratio. *Compares with values obtained before BPV. Reprinted with permission of Wiley-Liss, a division
2.7 2 0.8
O2 sat, oxygen
of John
Wiley&Sons,
< ,001
saturation;
Inc.20
PA, pulmonary
t
1.4
2.6 2 0.7
artery;
Qp, pulmonary
..l .OOl
. .Ol x .OOl
blood
flow;
CATHETER
THERAPY
OF PULMONARY
STENOSIS
infundibular obstruction. This child might need surgical resection of infundibular obstruction at a later date. Infundibular obstruction resolved in the remaining patients in a manner described by UP and others.71 Conclusion
Balloon pulmonary valvuloplasty appears to offer excellent relief of pulmonary oligemia, systemic arterial hypoxemia, and right ventricular hypertension in patients with pulmonary stenosis with intact ventricular septum and right-to-left atria1 shunting. Based on the data presented, it is suggested that balloon valvuloplasty is the procedure of choice for treatment of this group of patients. PULMONARY
STENOSIS WITH VENTRICULAR RIGHT-TO-LEFT SHUNT
The group of patients considered under this section are those that have severe pulmonary stenosis in association with a (usually) large interventricular communication. The most common type of defect in this category is tetralogy of Fallot (TOF). Other defects include transposition of the great arteries, double-outlet right (or left) ventricle, and ventricular inversion (corrected transposition of the great arteries), all with a large ventricular septal defect and severe pulmonic stenosis. Other defects, such as single ventricle and tricuspid atresia, fall into this category, provided pulmonary stenosis is present. Indications
The indications for balloon pulmonary valvuloplasty that we have used6,20 were cardiac
Fig 22. Selected cineangiographic frames from patients with tetralogy of Fallot (A) and d-transposition of the great arteries (B), demonstrating two sites of pulmonary outflow obstruction (two arrows). When the pulmonary valve obstruction is relieved by balloon valvuloplasty, the subvalvar obstruction remains and prevents flooding of lungs. Ao, aorta; LV, left ventricle; PA, pulmonary artery; RV, right ventricle. Reprinted with permission of Wiley-Liss, a division of John Wiley & Sons, Inc.za
139
defects not amenable to surgical correction for the age and size of the patient at the time of presentation, but, at the same time, requiring palliation for pulmonary oligemia. Symptoms related to hypoxemia and polycythemia are indications for intervention. Hypoplasia of the pulmonary valve ring, main and/or branch pulmonary arteries, is another indication even if symptoms are not present. The presence of two or more sites of obstruction to pulmonary blood flow (Fig 22) was considered a prerequisite when using balloon valvuloplasty, because if valvar stenosis is the sole obstruction, relief of such an obstruction may result in a marked increase in pulmonary blood flow and elevation of pulmonary artery pressure and resistance. The technique of balloon valvuloplasty for this group of children is described in Appendix 3. Results Immediate results. Balloon pulmonary valvuloplasty for infants with cyanotic congenital heart defects with pulmonary oligemia was used by uGZfl and others69s’40-i43to augment pulmonary blood flow. McCredie and associates@’ used balloon dilatation of the stenotic pulmonary valves in two patients, one with TOF and the other with tricuspid atresia, and reported improvement in exercise tolerance in both and improvement in oxygen saturation from 83% to 89% in one child. Boucek et alI4 were successful in performing balloon pulmonary valvuloplasty in seven of the eight patients in whom they attempted the procedure. The diagnoses in these seven patients were TOF in five; transpo-
P. SYAMASUNDAR
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three; and dextrocardia, ventricular inversion with ventricular septal defect, and valvar and subvalvar pulmonary stenosis in the final case. Following balloon pulmonary valvuloplasty, the arterial oxygen saturation increased from 67 & 13% to 83 + 13% (P < .Ol). The pulmonary blood flow index (2.1 t 0.8 L/min/m? v 3.2 ? 1.2 L/min/m2, P < .05), Qp:Qs (0.7 + 0.4 1’ 1.2 + 0.5, P < .02), and pulmonary artery pressure (16 + 5 mm Hg v 21 ? 11 mm Hg, P < .02) increased following balloon dilatation (Table 9). The pulmonary valvar gradients (52 ~fr16 mm Hg v 32 2 22 mm Hg) decreased (P < .05), whereas infundibular gradients (33 f 12 mm Hg v 42 & 16 mm Hg) and total pulmonary ventricular outflow tract (valvar plus subvalvar) gradients (77 ? 14 v 66 ? 12 mm Hg) remained unchanged (P > . 1) after valvuloplasty. An example is shown in Fig 23. None required immediate surgical intervention. No complications were encountered during the procedure. All children were discharged home within 24 hours of the procedure. Follow-up results. There are limited follow-up data. Boucek et alr40 reported 0.5 to 2.8-year follow-up results; four TOF patients underwent surgical correction, one patient underwent systemic-to-pulmonary artery anastomosis, and the other two did not require surgical correction. Qureshi and associates14’ reported follow-up observations after balloon angioplasty of 15 TOF patients. Seven children did not require further palliation during a mean follow-up period of 12.9 months (3.5 to 26 months). Four children required systemic-to-
sition of the great arteries, ventricular septal defect, and pulmonic stenosis in one; and ventricular inversion, ventricular septal defect, and pulmonic stenosis in the final patient. The systemic arterial oxygen saturations increased from 72 + 5% to 83 2 5% (P < .005). The pulmonary blood flow and pulmonary arterial pressure also increased. Qureshi et al141 reported their observations after balloon dilatation of the pulmonary valve in 15 patients with TOP, the systemic arterial oxygen saturation increased in the majority of patients. In four of these children, either no significant change or a deterioration in oxygen saturation occurred, and they received systemic-to-pulmonary artery shunts 1.6 months (0 to 3 months) after the procedure. Six children did not require further intervention. They concluded that balloon dilatation may be useful in the management of infants with severe TOF, and that it should be considered for the initial palliative treatment.141 Mehta and Perlman142 reported a single patient with TOF in whom balloon pulmonary valvuloplasty increased oxygen saturation from 80% to 90%. The Madison experience with this procedure, including that previously reported,6~2(i,” was in 11 infants with cyanotic congenital heart defects, aged 3 months to 3 years (median, 10 months), weighing 5.4 to 16 kg (median, 8.0 kg), who underwent balloon pulmonary valvuloplasty as a palliative procedure to improve pulmonary oligemia. The diagnoses in these cases were TOF in 7 children; transposition of the great arteries, with ventricular septal defect and valvar and subvalvar pulmonary stenosis in Table
Arterial
9. Results
of Balloon
Pulmonary
0, sat, %
Qp:Qs Qp, L/min/m2 PA pressure, mm Hg Pulmonary valve gradient, mm Hg lnfundibular gradient, mm Hg Total gradient across, PV outflow, mm Hg Hemoglobin,
9%
Abbreviations: Qp, pulmonary *Compares tP > 0.1. Reprinted
SPV, balloon pulmonary blood flow; PA, pulmonary with with
value permission
obtained
before
of Wiley-Liss.
Valvuloplasty-Ventricular
Right-to-Left
Shunt
Group
4 to 36 Months After BPV (N = 11)
P Value’
Before BPV (N = 11)
Immediately after BPV (N = 11)
P Value*
67 + 13 0.7 + 0.4
83 + 13 1.2 t- 0.5
.l > .05
0.8 5 16 12
77 + 14 16.5 + 2.9
-
valvuloplasty; O2 sat, oxygen artery; PV. pulmonary ventricle,
saturation;
EPV. a division
RAO
of John
Wiley
81 Sons,
lnc.*0
Op:Qs,
1.7 6 7 18t 13
> .l
15.8 + 2.7
> .1
pulmonary-to-systemic
rt k 2 I?
> .05 c ,001
c .02
blood,
flow
ratio;
CATHETER
THERAPY
OF PULMONARY
STENOSIS
141
Fig 23. Pressure pullback tracings across the pulmonic valve and right ventricular outflow tract before (A), 15 minutes (6) and 12 months (C) after balloon pulmonary valvuloplasty in a patient with tetralogy of Fallot. Note both valvar and infundibular gradients were present before valvuloplasty (A), whereas the valvar gradient almost completely disappeared and infundibular gradient persisted immediately after (B) and 12 months (C) following valvuloplasty. MPA, main pulmonary artery; RVB, right ventricular body; RVO, right ventricular outflow tract. (Reprinted with permission of WileyLiss, a division of John Wiley & Sons, Inc.20)
pulmonary artery shunt operations 0 to 3 months (mean, 1.6 months) after angioplasty. The final four patients had a corrective operation 6 to 16 months (mean, 8 months) after balloon dilatation. From the Madison group,20 all 11 children have been followed for 6 to 36 months (13 k 10 months) with pulse oximetry and hemoglobin determinations. Cardiac catheterization was also performed in all 11 children 4 to 12 months (median, 11 months) following valvuloplasty. Arterial oxygen saturation (82 + 9%), pulmonary blood flow (4.0 +- 1.7 L/min/m*), and
Qp:Qs (1.3 k 0.7) remain unchanged (P > .l) from the immediate postvalvuloplasty values, but remain improved (P < .05 to “001) when compared with prevalvuloplasty values (Table 9). The hemoglobin level (15.8 2 2.7 g %) did not change (P > .l) when compared with the prevalvuloplasty value of 16.5 + 2.9 gm %. The pulmonary valve gradient (18 k 7 mm Hg) remains improved both when compared with that recorded before (P < .OOl) and immediately after (P < .0.5) valvuloplasty (Table 9). The subvalvar (53 + 18 mm Hg) and total pulmonary ventricular outflow tract (69 2 13 mm Hg)
P. SYAMASUNDAR
142
gradients remain unchanged (P > .l). An example is shown in Fig 23. None of the patients had significant elevation of peak systolic pulmonary artery pressure: 22 2 6 mm Hg; range 12 to 30 mm Hg. Four children with TOF underwent successful total surgical correction 4 to 24 months (12 + 9 months) following valvuloplasty. Two of these children had very small pulmonary arteries before valvuloplasty and were initially considered unsuitable for total surgical correction. Approximately 12 months later, the pulmonary artery anatomy improved (Fig 24) and total surgical correction was performed without incident. The other two children were operated on 4 and 5 months after balloon valvuloplasty because they developed cyanotic spells. The remaining 3 children with TOF are clinically doing well and await surgery. Two children in the transposition group showed evidence for significant hypoxemia on follow-up and Blalock-Taussig shunts were performed 6 and 18 months following initial balloon valvuloplasty. Increase in the size of the pulmonary artery, as previously reported,6 was observed. The remaining transposition patient and the single patient with corrected transposition (ventricular inversion) are clinically well and no further intervention is planned. Complications Complications have been remarkably minimal. A transient decrease in systemic arterial saturation occurs while the balloon is inflated but rapidly improves following balloon deflation. Surprisingly, cyanotic spells following balloon valvuloplasty have not been a problem,
RAO
presumably because of improvement of pulmonary blood flow following the procedure. However, increasing cyanosis has been observed by some workers.14* Hypotension during balloon inflation, which is so common in balloon dilatation of pulmonic stenosis with intact ventricular septum,23 is usually not observed in this group of patients, presumably because the flow through the ventricular septal defect provides adequate systemic ffow. Pulmonary arterial tear’“” has been reported in a 3-year-old child, which was noted at the time of total surgical correction 15 months following valvuloplasty. Femoral venous occlusion may be observed at follow-up”.“’ but without adverse effects. Comments Lababidi and colleaguesh4,“’ were the first to report balloon valvuloplasty in patients with tetralogy of Fallot. However, they did not advocate the procedure for patients with TOF. While evaluating the mechanism of balloon pulmonary valvuloplasty,h4J23 they examined the role of balloon valvuloplasty in TOF and suggested that in the presence of combined infundibular and valvar pulmonic stenosis, balloon fixation by the infundibulum causes retraction of the balloon into the ventricle during systole, which may cause avulsion of the valve cusp. Therefore, they did not recommend balloonvalvuloplasty in these patients.“” Subsequently, several groups of workers, including our group, 6,20.21,69,140-143 reported successful balloon pulmonary valvuloplasty to improve pulmonary oligemia, which were just reviewed. The immediate results of balloon pulmonary valvuloplasty in this group of patients appear
CATHETER
THERAPY
OF PULMONARY
STENOSIS
good and attained the objective of improving pulmonary oligemia and systemic arterial hypoxemia. Immediate surgical intervention was avoided in most cases. Intermediate-term results are also good, the augmentation of pulmonary blood flow continuing to be present at follow-up in most children. The size of the pulmonary arteries improved in most patients, making them more suitable for further palliative or total surgical corrective procedure. Battistessa et a1’45 reported their observations at surgery for TOF patients who had previously undergone balloon pulmonary valvuloplasty. Results in 27 patients (which included 15 patients previously reported by Qureshi141 and probably form a subgroup of their larger experience’“‘) were scrutinized. They found anatomic alterations in the right ventricular outflow tract in 20 (74%) patients, whereas no change was observed in 7 (26%). They also noted that there was no evidence for significant growth of the pulmonary valve annulus and that the need for a transannular patch was not abolished at the time of intracardiac repair. In view of the damage to the pulmonary valve mechanism and no evidence for enough growth of the pulmonary valve to obviate the need for transannular patch at a later corrective surgery, they were not very supportive of balloon valvuloplasty as a palliative procedure. Although these observations are important, we6.?0 and others1JnJJl.14hhave documented an increase in the size of the pulmonary artery and/or annulus following balloon pulmonary valvuloplasty. The increase in the pulmonary arteryiannulus size is demonstrated in a larger group of patients,13-i which included Battistessa’s patients.145 The increase (P < .OOl) in pulmonary valve annulus size was demonstrated in 24 patients who also increased their systemic arterial oxygen saturations following balloon valvuloplasty, and this increase in pulmonary annulus size was greater (P < .00.5) than expected from normal growth. This improvement in the size of the pulmonary arteriesh,"),l40.14~.14~ is similar to that observed following a Brock procedurei47J4x and systemicto-pulmonary arterial shunts.149-1s2 In view of the varied observations, it would seem prudent that balloon pulmonary valvuloplasty in TOF (or any other cyanotic defects) should be performed in only selected patients.
143
The following criteria are proposed: (1) the infant/child requires palliation of pulmonary oligemia but is not a candidate for total surgical correction either because of the size of the patient, the type of the defect, or because of anatomic aberrations, (2) valvar obstruction is a significant component of the right ventricular outflow tract obstruction, (3) multiple obstructions in series (Fig 22) are present so that there is residual subvalvar obstruction after relief of pulmonary valvar obstruction and flooding of lungs is prevented. Once balloon valvuloplasty is decided on, balloons large enough to give a balloon/annulus ratio of 1.2 to 1.4 are recommended.6,‘,l?.‘0.“X New Developments Obstruction to the pulmonary outflow tract is usually at multiple levels in TOF; the sites of obstruction are pulmonary arteries, pulmonary valve leaflets, pulmonary valve ring, and infundibulum. Relief of valvar obstruction can, in some patients, increase forward flow and encourage growth of the pulmonary valve ring and pulmonary arteries, as discussed above. If severe infundibular stenosis is present, relief of pulmonary valve stenosis alone may not accomplish the objectives of relieving systemic hypoxemia and encouraging growth of the pulmonary arteries. Qureshi and associatesis’ used a Simpson coronary atherectomy catheter to perform infundibular myectomy in a 16mont h-old child with TOF. The systemic arterial saturation improved from 78% before the procedure to 85% a month later, and the right ventricular outflow tract became wider. They suggested that this type of transcatheter resection of the infundibulum may be important in the palliation of TOF. Further clinical trials of this method in selected patients are warranted to determine whether this method may serve as a useful adjunct to balloon pulmonary valvuloplasty in the management of TOF. Conclusion Balloon pulmonary valvuloplasty appears to offer excellent rehef of pulmonary oligemia and systemic arterial hypoxemia in patients with tetralogy of Fallot-type hemodynamics. Based on the data presented, it is recommended that balloon pulmonary valvuloplasty be used in the
144
P. SYAMASUNDAR
management of patients with cyanotic heart defects and pulmonary oligemia. It is an effective alternative to surgical creation of a systemicto-pulmonary arterial anastomosis, thus avoiding potential complications associated with surgical shunts.154-157The procedure is likely to be beneficial if the valvar obstruction is the dominant obstruction. The presence of two or more obstructions in a series is desirable to prevent flooding the lungs when the procedure proves successful. NARROWED
SYSTEMIC-TO-PULMONARY ARTERY SHUNTS
Cyanotic congenital heart defects with pulmonary oligemia secondary to severe pulmonary stenosis or pulmonary atresia usually require a systemic arterial-to-pulmonary arterial shunt operation to augment pulmonary blood flow and to improve arterial oxygen saturation. Narrowing of these shunts can occur postoperatively with resultant inadequate oxygenation. These narrowed shunts can be balloon dilated.22J58-162Gibbs and associatesls8 reported balloon dilatation of a narrowed Waterston (ascending aorta-to-right pulmonary artery) shunt in a 13-year-old child with pulmonary atresia and multiple shunts. The size of the stoma of the Waterston anastomosis was 3 mm. They initially used an &mm balloon catheter and did not observe “waisting” of the balloon and, therefore, repeated the procedure with a 12-mm balloon. There was a dramatic increase in arterial oxygen saturation (76% to 96%) and pulmonary artery pressure (15/ 11 mm Hg to 42130 mm Hg). However, the child died 12 hours later because of unilateral pulmonary edema. Autopsy findings were enlargement of the Waterston shunt to 10 mm and a congested and edematous right lung. The other shunts were completely occluded without any blood supply to the left lung. The complication in this child may have been caused by the use of a very large balloon to dilate the Waterston shunt. More data and experience with this lesion are necessary before making any definitive recommendation. The experience in dilating narrowed classical and modified Blalock-Taussig (BT) shunt 22~159-162 is more favorable and will be discussed in detail.
RAO
Indications The indication for dilating narrowed BT shunts is the presence of cyanotic heart defects not amenable to total surgical correction at the time of presentation either because of age and size of the patient or because of anatomic complexity, while at the same time requiring palliation of pulmonary oligemia.2’ The majority of these patients have associated pulmonary atresia or have a pulmonary artery that cannot be catheterized directly, either because of the severity of obstruction or because of an abnormal or atypical position. Measurement of pulmonary arterial pressure and demonstration of pulmonary arterial anatomy are of obvious value in the overall patient management. This is an additional indication for balloon angioplasty of narrowed BT shunts. The technique of balloon angioplasty is described in Appendix 4. Results Acute results. Balloon angioplasty of a narrowed BT shunt was initially reported by Fischer et alls9 and subsequently by others.‘**h0-163Fischeris dilated a narrowed classical BT shunt in a 4-year-old child and increased systemic arterial saturation from 68% to 80%. Marx and associates160 successfully performed this procedure in five of six patients in whom they attempted the dilatation. Two of the five patients benefited markedly and one moderately. In the remaining two patients, no benefit could be shown. It is not clear whether these are classic or modified BT shunts that were dilated. Parsons and his colleagues161 balloon-dilated proximal stenosis of a modified right (GoreTex; Gore & Associates Inc, Elkton, MD) BT shunt in a 17-month-old child with tricuspid atresia and increased arterial oxygen saturation from 73% to 80%. There also was angiographic improvement. Rheuban and Carpenter,162 while discussing pediatric interventional procedures, presented angiograms of a patient that underwent balloon dilatation of a narrowed proximal anastomosis of what appears to be a modified (Gore-Tex) BT shunt. Significant angiographic improvement is noted, but no oxygen saturation data were provided. Marks and associates’“” balloon-dilated classic BT shunts in five chil-
CATHETER
THERAPY
OF PULMONARY
STENOSIS
dren, aged 11 to 67 months, and increased their oxygen saturation from 73 + 9% to 84 f 3%. The Madison experience with this procedure, including that previously reported,22 is in eight children. There were four boys and four girls with a weight range of 6.2 to 19.6 kg (mean, 11.0 kg). The diagnoses in these children were pulmonary atresia in four (one with intact ventricular septum, two with large ventricular septal defects, and the final patient with mitral atresia, hypoplastic left ventricle, and double-outlet right ventricle), tricuspid atresia in three, and single ventricle, single atrium, and severe valvar and subvalvar pulmonic stenosis in the final patient. Each of these children underwent a BT shunt either in the neonatal period (five patients) or in early infancy (three patients). All children were cyanotic with increased hemoglobin values, 19.0 2 2.7 gm % (mean + SD), with a range of 14.8 to 22.1 gm %. Three children were severely symptomatic and were unable to attend school. Three toddlers were severely cyanotic with hyperpnea. The remaining two children were cyanotic and tolerated normal activity. There was moderate to severe hypoxemia with a mean oxygen saturation of 71% (SD * 7%), with a range of 62% to 82%. The pulmonary artery pressure was low normal in four children in whom the pulmonary artery pressure could be measured before angioplasty. In one child with long segmental narrowing of the left subclavian artery (in a patient with right aortic arch) proximal to its entry into the left pulmonary, there was no significant improvement in the oxygen saturation or in the angiographic appearance of the BT shunt. The angioplasty was considered to be a failure, and the child underwent a right BT shunt within several weeks after balloon angioplasty. In the remaining children, there was significant improvement. The arterial oxygen saturation increased from 71 + 7% to 81 & 4% following balloon angioplasty. Pulmonary artery pressures were measured in each case following angioplasty, and the peak systolic pressure was 14 f 5 mm Hg, with a range of 9 to 23 mm Hg; none had elevated pulmonary artery pressures. Angiographic improvement of the BT shunt with a greater degree of opacification of the pulmonary circuit was observed in each of the seven
145
children. Examples are shown in Figs 25, 26, and 27. No complications were encountered during the procedure. Follow-up results. Follow-up data after balloon angioplasty of narrowed BT shunts is scanty. Fischer159 commented that the dilated shunt was patent 2 months after angioplasty. Marxr60 stated that on short-term follow-up, three patients (of five) improved and two did not benefit. Parson’@ patient maintained clinical improvement for 4 months following angioplasty. At repeat catheterization, the arterial oxygen saturation was 76% (which was 73% before angioplasty and 80% immediately after angioplasty), and the dilated proximal anastomotic site was patent without restenosis or aneurysmal formation. MarkG3 followed five children for 6 -t 2 months after angioplasty, and their oxygen saturation by pulse oximetry remained improved at 82% to 90%. Two of these five patients were recatheterized 39 and 50 months after angioplasty, and the diameter of the dilated shunt, oxygen saturation, and pulmonary artery pressure remained unchanged at follow-up when compared with immediate postangioplasty values. From the Madison series, the single child with failed balloon angioplasty (of left BT shunt) underwent successful right BT shunt and demonstrated improved arterial oxygen saturation. The remaining seven children were followed for 3 to 24 months (mean, 12 months). The children with symptoms of exercise intolerance improved markedly, although all of them remained cyanotic. Hemoglobin levels decreased from 19.0 f 2.7 gm % to 17.1 2 1.9 gm %. Arterial oxygen saturation by pulse oximeter remains improved as a group (78 -+ 10%). Auscultation showed a continuous murmur of the shunt in five patients, but on echo-Doppler study, the shunt was patent in six children. Repeat catheterization was undertaken in two children because of progressive hypoxemia. The O2 saturations decreased. Although the shunts were patent, because of continued hypoxemia, BT shunts were successfully performed on the contralateral side 8 and 10 months after the balloon angioplasty. The remaining children were doing well clinically with continued palliation of pulmonary oligemia.
146
Complications No complications were detected either in the Madison series or the patients reported by other workers.r59-163 It is somewhat surprising that there was no significant hypoxemia during balloon inflation (and consequent complete oc-
Fig 26. Right innominate artery (RI) cineangiographicframes before (A) and immediately following (B) balloon angioplasty. Note slight, but significant, improvement in the narrowed segment of the right subclavian artery (RSC) and the anastomotic site (arrow). LPA, left pulmonary artery; RCC, right common carotid artery; RPA, right pulmonary artery.
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elusion of BT shunt); presumably, this is because of alternative sources of pulmonary blood supply either through bronchial collateral vessels, a contralateral BT shunt, or through the stenotic pulmonary valve.” Because of reported instances of acute block-
CATHETER
THERAPY
OF PULMONARY
STENOSIS
Fig 27. Aortic arch cineangiographic frames with the catheter tip positioned very close to the left innominate artery. Note the two areas of narrowing (arrows) in the left subclavian artery before balloon angioplasty (A), which have completely disappeared after angioplasty [B). Cl, arterial catheter in the aorta (right aortic arch); C2, venous catheter in superior vena cava; LCC, left common carotid artery; RPA, right pulmonary artery.
age of the BT shunts following catheter manipulation,1@J65 such complications can occur following balloon angioplasty. Close monitoring to ensue patency of the BT shunt in the postdilatation period is highly recommended. If such blockage occurs, consideration should be given to administration of intravenous streptokinase165or similar thrombolytic agents. Comments The immediate results of balloon angioplasty of narrowed BT shunts are good, and they accomplish the objective of improving pulmonary blood flow and hypoxemia in most patients. It appears that balloon angioplasty can be performed in both classical and modified (GoreTex) BT shunts. These results are similar to those following balloon pulmonary valvuloplasty for cyanotic congenital heart defects.6.2(1.69.140-‘43 During the short follow-up period, more than 50% of patients maintain symptomatic relief, whereas the others required additional palliation or correction. There are other benefits: in two children from the Madison study group with either complete or almost complete blockage of the BT shunt no catheter could be advanced into the BT shunt, but a balloon-on-a-wire could be advanced, with which the shunt was dilated, followed by the introduction of a catheter. This has resulted in obtaining pulmonary artery pressures directly and in good quality pulmonary arteriograms (Fig 28) information of obvious value in patient management, in addition to improving the arterial oxygen saturation.
Although there are many different ways of catheterizing the BT shunt and dilating it, the method that was used in the Madison series, namely (1) positioning an end-hole type of catheter in the vicinity of subclavian artery, passing a flexible (0.014 in) guidewire into the BT shunt and pulmonary artery and dilating with low-profile coronary-dilating catheters, and (2) failing the above, passing a balloon-on-awire to initially dilate the shunt and then redilate with a coronary-dilating catheter has been successful. OtherPO have used Cook Cobra and Headhunter catheters (Cook, Inc., Bloomington, IN) with success. It is not clear as to what is the most appropriate-sized balloon that should be used for balloon angioplasty; it should probably be 2.5 to 3.0 times the narrowest site. In general, balloons as large as the size of the subclavian artery feeding the shunt should be used, and such large balloons may be necessary to achieve adequate dilatation.22 As pointed out by Marx,iho use of small balloons may not produce adequate improvement in oxygen saturation and may have been the reason for only modest success of this procedure in his patients.i60 When there is difficulty in advancing a large balloon-dilating catheter, use of an extra-stiff guidewire (for example, extra-stiff Amplatz Cook guidewire [Cook, Inc.]) is helpful and recommended. Use of heparin (100 U/kg) during the procedure is recommended to prevent thrombosis. We continue heparinization for 24 hours following the procedure to prevent acute blockage165 following angioplasty. We do not use platelet-
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Technique of catheterization of Blalock-Taussig shunt when it is completely or almost completely occluded. A right Fig 28. innominate (RI) artery cineangiographic frame showing right common carotid (WC) artery and right subclavian (WC) artery; the latter is completely blocked. Having not been able to catheterize it in the usual manner, a 2-mm balloon-on-a-wire was advanced into the shunt and the balloon was inflated (B). Subsequently, a 5-F multi-A2 catheter was introduced into the pulmonary artery and a cineangiogram (C)was performed. Note the main (MPA), right (RPA), and left (LPA) pulmonary arteries; the LPA was not completely opacified because of flow from the left Blalock-Taussig shunt. Then a 4-F coronary balloon angioplasty catheter carrying a 4-mm balloon was positioned across the narrowed BT shunt (D and E); note “waisting” of the balloon (D) during the initial phases of balloon inflation. Right innominate artery cineangiogram (F) following balloon angioplasty showing the open Blalock-Taussig shunt and opacification of the pulmonary artery through the shunt, although the shunt is still narrow. (Reprinted with permission.22)
inhibiting drugs. Others16’ have used aspirin and dipyridamole in the postdilatation period. The type of BT shunt constriction that responds to balloon angioplasty is not clear. The Madison experience indicates that diffusely narrowed shunts do not favorably respond, whereas discrete obstructions are likely to improve. Conclusion Based on the Madison experience and that reported by others, 159-163 balloon angioplasty of narrowed BT shunts is recommended as the procedure of choice to augment pulmonary blood flow if the patient’s size or complexity of the cardiac defect will not permit total surgical correction, but, at the same time, the child
requires palliation of systemic hypoxemia pulmonary oligemia. PULMONARY
and
ATRESIA
Pulmonary atresia may be present with or without a ventricular septal defect. Multiple palliative procedures are usually necessary’6h.‘h7 before any corrective surgery. Pulmonary atresia patients with ventricular septal defects usually have an underdeveloped main pulmonary artery and/or infundibular atresia and may not be amenable to transcatheter treatment, to be discussed below, although an occasional patient may have isolated valvar atresia. Patients with pulmonary atresia with intact ventricular septum usually have a well-developed main pulmo-
CATHETER
THERAPY
OF PULMONARY
STENOSIS
nary artery with only valvar atresia, although some patients in this category may also have infundibular atresia. Transcatheter approaches that have potential utility in the management of valvar pulmonary atresia with intact ventricular septum will be discussed in this section. These methods could also be used in the ventricular septal defect group, provided the infundibulum and main pulmonary artery are wide open. The prognosis for patients who have pulmonary atresia with intact ventricular septum is poor with or without conventional surgical intervention.‘h”‘“8-‘70 Therefore, we suggested166,‘7’ the adoption of a comprehensive medical and surgical treatment program leading to complete surgical correction of the lesion. The objectives of such a program were (1) to relieve hypoxemia and acidosis by a timely and appropriate procedure to increase pulmonary blood flow at initial presentation (usually in the newborn period), (2) to facilitate adequate egress of blood from the right atrium, and (3) to stimulate the growth of the right ventricle. The objectives of the program can often be achieved by appropriately timed, multiple surgical procedures. These have been detailed elsewhere.‘@j Two transcatheter treatment strategies have been suggested for the management of these difficult patients:“?J7” (1) primary perforation of the atretic pulmonary valve by transcatheter methods’7’ and (2) limited opening of the pulmonary valve at surgery,‘7.7 both followed by balloon valvuloplasty. Transcatheter Peforation Valve
of Atretic Pulmonary
Perforation of the atretic pulmonary valve with a blunt wire, though feasible,174 is not generally used. Lee, Riemenschneider, and associates’75.‘7h used laser irradiation to relieve obstructed valves and create atria1 septal defects in animal models and human postmortem specimens. Arapov et al used laser for pulmonary valvotomy introperatively.‘77 Qureshi et al”’ used laser via a catheter to perforate an atretic pulmonary valve and followed this up with balloon enlargement of the pulmonary valve. They were successful in perforating the pulmonary valve with a laser (Nd-YAG laser) wire in four of the five patients in whom they tried this procedure. Perforation of the right ventricle and cardiac tamponade occurred in
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the fifth patient. Increase in the pulmonary artery pressure and decrease in right ventricular pressure occurred in all four patients. At 2- to 6-month follow-up, forward flow across the laser-opened pulmonary valve was demonstrated; there was a 50 to 70 mm Hg residual gradient across the pulmonic valve. The oxygen saturations ranged from 70% to 87%. These preliminary observations are of interest, and with further refinement of the technique and additional clinical trials, the laser techniques are likely to be useful in the management of these complex pulmonary atresia patients. Surgical Pulmonary Valvotomy Followed by Balloon Valvuloplasty
Latson and associates173 advocated limited incision (4 mm) in the atretic pulmonary valve by direct vision via the main pulmonary artery in order to allow antegrade flow and future access for balloon dilatation. They performed this procedure either at the time of the initial shunt procedure or at a subsequent sitting. They performed balloon pulmonary valvuloplasty at 2 to 12 months of age and reduced the pulmonary valvar gradients to less than 20 mm Hg. The right ventricular peak systolic pressure was less than 60% of systemic pressure. They applied this technique in four infants. Two patients had undergone complete repair, and the other two are acyanotic and have biventricular physiology. Kanh5 Sullivan,55 and their associates also attempted balloon dilatation following surgical pulmonary valvotomy for pulmonary atresia but without success. Ballerini et a176also performed balloon valvuloplasty after surgical valvotomy for pulmonary atresia with intact ventricular septum; in six patients, they reduced peak pulmonary valve gradients from 50 ? 8 mm Hg to 30 & 6 mm Hg. The Madison experience in a single patient is similar to that reported by Ballerini.76 Both the above approaches are innovative methods and may have clinical utility. Appropriate clinical trials are warranted to assess their effectiveness and safety. SUMMARY
AND CONCLUSIONS
The role of transcatheter methods in the management of pulmonary outflow tract obstruc-
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tion are discussed in this review. Balloon pulmonary valvuloplasty for relief of isolated pulmonary valve stenosis has been successfully used by many investigators and is the procedure of choice for the management of these lesions. Supravalvar pulmonic stenosis, if discrete, can be relieved by balloon dilatation. Cyanotic children with interatrial right-to-left shunts secondary to severe valvar pulmonary stenosis respond in a manner similar to that observed with isolated pulmonary valve stenosis. In these patients, balloon valvuloplasty is the treatment of choice and may be corrective in most patients. In patients with interventricular right-to-left shunting secondary to pulmonary outflow tract obstruction and in patients with narrowed BT shunts, balloon dilatation may be an effective palliative procedure in a substantial proportion of patients obviating the need for an initial or second palliative shunt. Balloon dilatation is recommended if the patient’s size or cardiac anatomy make them unsuitable for safe total surgical correction. In patients with pulmonary atresia, either initial opening of the atretic pulmonary valve by laser or by surgery with subsequent balloon dilatation are potentially beneficial in reducing the total number of surgical procedures that these children are likely to require. However, further clinical trials are needed before their general use. ACKNOWLEDGMENT The author wishes to acknowledge with thanks the contributions to this material by the past and present colleagues in pediatric cardiology and cardiovascular sur-
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gery, including Drs M. Brais, P.S. Chopra, F. Kutayli, J. Levy, M.K. Mardini, L. Solymar. M.K. Thapar. and A.D. Wilson. Thanks are also due to Nanette Kelsey for her assistance in the preparation of the manuscript.
APPENDIX 1. TECHNIQUE OF BALLOON VALVULOPLASTY IN ISOLATED PULMONARY VALVE STENOSIS The indications for catheter intervention (described previously) are usually those prescribed for surgical intervention. Once balloon dilatation is decided on (1) a No. S- to 7-F multi-A-2 (Cordis) catheter is introduced percutaneously into the femoral vein and advanced across the pulmanic valve, and then into the left pulmonary artery: (2) a 0.014- to 0.035~in J-shaped guidewire is passed through the catheter into the distal left pulmonary artery; (3) a No. 4- to 9-F balloon dilatation catheter is advanced over the guidewire and the balloon is positioned across the pulmonary valve: and (4) the balloon is inflated with diluted contrast material to approximately 3 to 5 atmospheres of pressure (Fig 29). The pressure of inflation is monitored with the help of any of the commercially available pressure gauges. The recommended duration of inflation is 5 seconds. Usually a total of three to four balloon inflations are performed 5 minutes apart. A double-balloon technique (two balloons simultaneously inflated across the stenotic region) is used when the valve annulus is too large to dilate with a commercially available single balloon: and (5) mea surement of pressure gradients across the pulmonic valve and angiographic demonstration of the relief of obstruction are performed. Recordings of heart rate, systemic pressure. and cardiac index before and after balloon dilatation are made to ensure that any change in pressure gradient is not related to a change in cardiac index but is indeed related to the procedure. The procedure is generally performed with the patient sedated (usually with a mixture of meperidine. promethazinc, and chlorpromazine, administered intramuscularly) although some cardiologists use ketamine” or general anesthesia.““,id
Fig graphic tation pulmonic of the phases which ished balloon
29. Selected cineradioframes of a balloon dilacatheter placed across the valve. Note “waisting” balloon during the initial of balloon inflation (A), is almost completely abolduring the later phases of inflation (6).
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STENOSIS
Other aspects of importance for successfully accomplishing balloon angioplasty are as follows: 1. Difficult femoral venous access. Sometimes, it may be difficult to cannulate the femoral vein percutaneously either because of technical problems or because of femoral vein thrombosis secondary to previous catheterization and/or surgery. Cut down and isolation of the saphenous veinfemoral vein junction may be performed, and catheterization and balloon valvuloplasty can be accomplished via the saphenous venous bulb. When femoral venous access is not possible, balloon pulmonary valvuloplasty may be performed via an axillary venous55.5h or internal jugular venousi7 approach. The latter two approaches are also useful in the presence of infrahepatic interruption of the inferior vena cava with azygos or hemiazygos continuation. 2. Passing an end-hole catheter across the pulmonic valve. This may be difficult in some patients, particularly in young children and neonates. In such occasions, several maneuvers may be used: (1) use an end-hole catheter (usually a multi-A-2), position it just underneath the pulmonary valve, and advance the floppy end of a straight guidewire through the tip of the catheter into the main pulmonary artery: (2) use a balloon-wedge catheter. position it just beneath the pulmonic valve, and quickly deflate the halloon and advance the catheter into the main pulmonary artery. Failing this, use a guidewire, as described earlier; (3) use a flexible, steerable coronary guidewire through an end-hole catheter; (4) we have encountered one child in whom we could not advance any catheter across the right ventricular infundibulum because of severe infundibular constriction. In this child, administration of propranolol (0.1 mgikg intravenously (IV) slowly) made it possible to pass a catheter across the pulmonary valve and eventually balloon pulmonary valvuloplasty.r8 3. Choice of size of balloon dilatation catheter. The current recommendations are to use a balloon that is 1.2 to 1.4 times the size of the pulmonary valve annulus. These recommendations are formulated on the basis of immediatesx and follow-up results.ss,‘3 For further discussion of the reasoning behind such recommendations, the reader is referred to these publications.ss~13~L5 Balloons larger than 1.5 times the size of the pulmonary valve annulus are not
Fig 30. Selected tine frames of two balloon catheters placed across the pulmonary valve showing “waisting” of the balloons [arrows) during the initial phases of balloon inflation (A), which is completely abolished after complete inflation of the balloons (B).
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recommended because of potential damage to the right ventricular outflow tract caused by use of large balloons.5y However. it may be advisable to use a large balloon to produce a ballooniannulus ratio of 1.5 when pulmonary valve dysplasia is present.‘” When the pulmonary valve annulus is too large to dilate with a single balloon, valvuloplasty with simultaneous inflation of two balloons across the pulmonary valve annulus (Fig 30) should be performed. When two balloons are used, the following formula is used to calculate the effective balloon sizes:
D,+Dz+n
i
;+?
1
T
where Dr and D: are diameters of the balloons used. Although the double-balloon technique is not superior to a single-balloon technique,*J”,?’ it does reduce injury to the femoral veins because smaller-sized catheters can be used. Some workersh0-63 have advocated bifoil and trefoil balloons with the idea that there will be forward flow around the balloon during balloon inflation. Although such attempts to allow forward flow during balloon inflation are laudable, there may not be any significant forward flow in view of the fact that the balloons used for pulmonary valve dilatation are larger than the valve annulus. 4. On occasion, it may be difficult to advance the balloon dilatation catheter across the pulmonicvalve. It is important to avoid kinking or looping of the guidewire to prevent such a problem. Replacement of the guidewire with an extra-stiff Amplatz guide may circumvent the problem. 5. Sometimes it may not be feasible to advance an appropriate-sized balloon dilatation catheter across the pulmonic valve even after having a guidewire across it. In such situations, we use smaller-sized 4- to 6-mm balloons on a 4. or 5-F catheter initially to predilate followed by larger. more appropriate-sized balloons. This technique is also helpful when dilating very severely stenotic pulmonary valves and in small infants.
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Fig 31. Selected cineradiographic (lateral view) frames of a balloon dilatation catheter placed across the pulmonic valve in an infant with tetralogy of Fallot. Note “waisting” of the balloon during the initial phases of balloon inflation (A), which is almost completely abolished during the later phases of balloon inflation(B). (Reprinted with permission of Wiley-Liss, a division of John Wiley & Sons, Inc.ro)
APPENDIX 2. TECHNIQUE OF BALLOON DILATATION IN PULMONARY STENOSIS WITH ATRIAL RIGHT-TO-LEFT SHUNT The procedure of balloon pulmonary valvuloplasty in this condition is exactly the same as that used for isolated valvar pulmonary stenosis, described in Appendix 1. However. the procedure may be slightly more difficult to accomplish because of greater severity of the pulmonary outflow obstruction and a more frequent association of right ventricular hypoplasia and infundibular obstruction. Sometimes, even introducing a 5-F catheter across the pulmonary valve may cause bradycardia and hypoxemia because of further obstruction to pulmonary blood flow by the catheter. In such occasions, we leave a 0.014-in guidewire (wires used for coronary arterial lesions) across the pulmonic valve and then perform rapid dilatation with a 4-F coronary balloon dilatation catheter carrying a 4-mm low-profile balloon. Subsequent to that, a more appropriate-sized balloon dilatation catheter (1.2 to 1.4 times the size of the pulmonary annulus) can be used. Such progressive dilatation technique46,‘39 should be used when dealing with severe pulmo-
Fig 32. Right innominate artery cineangiogram initially entered with the help of a 0.014-in guidewire. shunt was dilated with angiographic improvement (Reprinted with permission.rr)
nary valve stenosis patients with supra-systemic right ventricular peak systolic pressure, and in neonates and small infants after spontaneous ductal closure. At times, it may be difficult to advance a catheter across the severe infundibular obstruction secondary to valvar stenosis; administration of propranolol (0.1 mg/kg) by a slow intravenous drip may help position the catheter across the right ventricular obstruction’s and allow balloon valvuloplasty. Hypotension during balloon inflation is minimal in these children because of maintenance of systemic perfusion by right-to-left shunting across the patent foramen ovale.i”D However, when monitored by pulse oximetry, the systemic arterial oxygen saturation decreases, which returns to normal after balloon deflation.
APPENDIX 3. TECHNIQUE OF BALLOON VALVULOPLASTY FOR PATIENTS WITH PULMONARY STENOSIS AND VENTRICULAR RIGHT-TO-LEFT SHUNTS The technique of balloon group of patients is similar
showing a markedly narrowed, Then a 3-mm balloon-on-a-wire (C). Catheters carrying larger
thread-like could balloons
pulmonary valvuloplasty to that used in isolated
in this valvar
right subclavian artery (A) which was be advanced across the shunt (B) and the could not be advanced into the shunt
CATHETER
THERAPY
OF PULMONARY
pulmonic stenosis described at times. it may be more valvuloplasty in this group valve stenosis group. An across the pulmonary valve size that is 1.2 to 1.4 times annulus is recommended.sr?
STENOSIS
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earlier in this review, although, difficult to accomplish balloon than in the simple pulmonary example of balloon catheters is shown in Fig 31. A balloon the size of the pulmonary valve
APPENDIX 4. TECHNIQUE OF BALLOON ANGIOPLASTY OF STENOSED BLALOCK-TAUSSIG SHUNTS After clinical assessment and after the usual laboratory studies suggested hypoxemia and pulmonary oligemia in association with a complex cyanotic heart defect, cardiac catheterization is performed both to confirm the clinical diagnosis and for possible balloon angioplasty. In each case, 100 U/kg of heparin (maximum 2,500 U) is administered immediately after introduction of an arterial catheter. After obtaining arterial oxygen saturation, right or left innominate artery (depending on the side of aortic arch) or subclavian artery cineangiogram is performed in order to determine the location and size of the Blalock-Taussig (BT) anastomosis. Attempts to advance a 5-F multi-A2 and/or a right coronary artery catheter into BT shunt and pulmonary artery are made. Failing this, the tip of the catheter is positioned in the mouth of the subclavian artery, or as close to it as possible. and a 0.014- to 0.035-m flexible-tip guidewire is advanced into the BT shunt and from there into the pulmonary artery. (In our previous experience with one child” with almost complete occlusion of the BT shunt [Fig 28A]. the tip of the catheter was wedged against the tip of the nipple-like blind end of the subclavian artery stump, and
the stiff end of an 0.018-in guidewire was gently threaded into the pulmonary artery and, eventually, balloon angioplasty was performed with a 4-mm balloon catheter.) Once the guidewire is positioned in the distal pulmonary artery, a low-profile balloon dilatation catheter is positioned across the narrowed BT shunt. The objective is to try to position a balloon with a diameter equivalent to the diameter of the subclavian artery. If a balloon angioplasty catheter could not be passed across the BT shunt, a balloon-on-a-wire* (2 mm or 3 mm) should be advanced across the narrowed BT shunt (Fig 32). Three successive inflations at 3 to 10 atmospheres of pressure, depending on the catheter manufacturer’s recommendations, of 5 to 10 seconds duration each is performed with a 5-minute interval in between each dilatation. The procedure of dilatation with the balloon-ona-wire and with a 4-F coronary dilation catheter can be performed through a 5-F sheath placed into the femoral artery at the beginning of the procedure. Larger balloon catheters may either be advanced via a 6-F sheath or dilatation could be performed without the use of a sheath. Fifteen minutes following the last balloon dilatation, pulmonary artery to aorta pressure pullback across the BT shunt and aortic saturation are obtained and innominate or subclavian artery cineangiogram repeated.
*The balloon-on-a-wire that we used is a USC1 Probe balloon-on-a-wire (USC1 Division of C.R. Bard, Billerica. MA).?’ Other available alteratives are ACS Hartzler Micro XR (Advanced Cardiovascular Systems, Inc., Santa Clara. CA) and Sci Med Dilating Guidewire (SCIMED Life Systems, Inc., Maple Grove, MN).
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10. Rao PS: Balloon dilatation in infants and children with dysplastic pulmonary valves: Short-term and intermediate-term results. Am Heart J 116:1168-1176. 1988 t 1. Rao PS: Indications for balloon plasty. Am Heart J 116:1661-1662,1988
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12. Rao PS, Thapar MK, Kutayli F: Causes of restenosis following balloon valvuloplasty for valvar pulmonic stenosis. Am J Cardiol62:979-982,1988 13. Rao PS: Further observations on the role of balloon size on the short-term and intermediate-term results of balloon pulmonary valvuloplasty. Br Heart J 60507-5 Il. 1988 14. Rao PS, Fawzy percutaneous balloon son with single balloon 1:257-262,1988
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16. Thapar MK, Rao PS: Significance of infundibular obstruction following balloon valvuloplasry for valvar pulmanic stenosis. Am Heart J 118:99-103. 1989 17. Rao PS: Causes of restenosis following balloon plasty/valvuloplasty: A review. Pediatr Rev Comm 172, 1990 18. Thapar MK, dynamic infundibular
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course of pulmonic stenosis. Circulation 56: 18-47. 1977 (suppl 1 ) 37. Tinker J. Howitt G, Markman P. et al: The natural history of isolated pulmonary stenosis. Br Heart J 27:151160.1965 38. Moller I, Wennevold A, Lyngborg KE: ‘The natural history of pulmonic stenosis: Long-term follow-up with serial heart catheterizations. Cardiology 58:193-X12. lY73 39. Mody MR: The natural history of uncomplicated valvar pulmonic stenosis. Am Heart J 90:317-321. 1975 40. Engle MA, Ito T, Goldberg HP: The fate of the patient with pulmonic stenosis. Circulation 30:5X56 I. 196-l 41. Stevenson JG. Kawabori I: Noninvasive determination of pressure gradients in children: Two methods employing pulsed Doppler echocardiography. J Am Co11 Cardiol 3:179-192. 1984 42. Rao PS: Doppler UhsoUnd in the prediction of transvalvar pressure gradients in patients with valvar pulmanic stenosis. Int J Cardiol 15:195-203. 1987 43. Lima CO, Sahn DJ. Valdes-Cruz LM, et al: Noninvasive prediction of transvalvar pressure gradient in patient? with pulmonic stenosis by quantitative two-dimensional echocardiographic Doppler studies. Circulation 67:X66-X71, lYX3 44. Kasturakis D, Allen HD. Goldberg SJ, et al: Noninvasive quantitation of stenotic semilunar valve area by Doppler echocardiography. J Am Co11 Cardio13: 12.56 1262, 1984 45. Yeager SB, Neal WA. Balian AA, et al: Percutaneous balloon pulmonary valvuloplasty. W V Med J 82:169-171~ 1986 46. Rao PS: Balloon valvuloplasty for pulmonic stenosis. in Cheng TO (ed): Percutaneous Balloon Valvuloplasty. New York. NY. Igaku-Shoin Medical Publishers, 1992. pp 365-420 47. Musewe NN, Robertson MA. Benson LN. ct al: The dysplastic pulmonary valve: Echocardiographic features and results of balloon dilatation. Br Heart J 57:364-370, 1987 48. DiSessa TG. Alpert BS. Chase NA, et al: Balloon valvuloplasty in children with dysplastic pulmonary valves. Am J Cardiol66:405-407.1987 49. Rey C, Marche P. Francart C, et al: Percutaneous transluminal balloon valvuloplasty of congenital pulmonary valve stenosis, with a special report on infants and neonates. J Am Coll Cardiol 11:815-820, 198X 50. Marantz PM, Huhta JC. Mullins CE. et al: Results of balloon valvuloplasty in typical and dysplastic pulmonary valve stenosis: Doppler echocardiographic follow-up. J Am Co11 Cardiol 12:476-479. 198X 51. Stanger P, Cassidy SC. Girod DA, CI al: Balloon pulmonary valvuloplasty: Results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. Am J Cardiol 65:775-783. 1990 5’2. Robertson M, Benson LN, Smallhorn JF-. et al: The morphology of the right ventricular outflow tract afterpercutaneous pulmonary valvotomy: Long-term follow-up. Br Heart J 58239-244, 1987 53. Tynan M. Baker EJ. Rohmer J. et al: Percutaneous balloon pulmonary valvuloplasty. Br Heart J 53:520-523. 1985 54. Chatfe A, Fairbrass MJ, Chatrath RR: Anaesthesia for valvuloplasty. Anaesthesia 43:359-361, 1988
CATHETER
THERAPY
OF PULMONARY
STENOSIS
55. Sullivan ID, Robinson PJ, Macartney FJ, et al: Percutaneous balloon valvuloplasty for pulmonary stenosis in infants and children. Br Heart J 54:435-441, 1986 56. Sideris EB, Baay JE, Bradshaw RL, et al: Axillary vein approach for pulmonic valvuloplasty in infants with iliac vein obstruction. Cathet Cardiovasc Diagn 15:61-63, 1988 57. Chaara A, Zniber L. Haitem NE, et al: Percutaneous balloon valvuloplasty via the right internal jugular vein for valvar pulmonic stenosis with severe right ventricular failure. Am Heart J 117:684-685, 1989 58. Radtke W. Keane JF, Fellows KE, et al: Percutaneous balloon valvotomy of congenital pulmonary stenosis using oversized balloons. J Am Coll Cardiol8:909-915, 1986 59. Ring JC, Kulik TJ, Burke BA: Morphologic changes induced by dilatation of pulmonary valve annulus with over-large balloons in normal newborn lamb. Am J Cardiol 55:210-214, 1986 60. Van den Berg N. Niemyer MG, Plokker TWM. et al: New triple-lumen balloon catheter for percutaneous (pulmonary) valvuloplasty. Cathet Cardiovasc Diagn 12:352-356, 1986 61. Meier B, Friedli 9, Oberhaensli I, et al: Trefoil balloon for percutaneous valvuloplasty. Cathet Cardiovasc Diagn 12:227-281, 1986 62. Thanopoulos BD, Margetakis A, Papadopoulos G, et al: Valvuloplasty with large trefoil balloons for the treatment of congenital pulmonary stenosis. Acta Paediatr Stand 78:742-746,1989 63. Meier B, Friedli 9, von Segesser L: Valvuloplasty with trefoil and bifoil balloons and long sheath technique. Herz l3:1-13, 1988 64. Lababidi Z, Wu JR: Percutaneous balloon pulmonary valvuloplasty. Am J Cardiol52:560-562, 1983 65. Kan JS, White RI Jr. Mitchel SE, et al: Percutaneous transluminal balloon valvuloplasty for pulmonary valve stenosis. Circulation 69:554-560, 1984 66. Kveselis DA. Rocchini AP, Snider AP, et al: Results of balloon valvuloplasty in the treatment of congenital valvar pulmonary stenosis in children. Am J Cardiol56:527532, 1985 67. Miller GAH: Balloon valvuloplasty and angioplasty in congenital heart disease. Br Heart J 54:285-289, 1986 68. Shrivastava S, Sundar AS, Muhkopadyaya S. et al: Percutaneous transluminal balloon pulmonary valvuloplasty: Long-term results. Int J Cardiol 17:303-314, 1987 69. McCredie RM, Lee CL, Swinburn MJ, et al: Balloon dilatation pulmonary valvuloplasty in pulmonary stenosis. Aust N Z J Med 16:20-23, 1986 70. Ali Khan MA. Al Yousef S, Mullins CE: Percutaneous transluminal balloon pulmonary valvuloplasty for the relief of pulmonary valve stenosis with special reference to double-balloon technique. Am Heart J I l2:158-166. 1986 71. Fontes VF, Sousa JEMR, Esteves CA, et al: Pulmonary valvuloplasty: Experience of 100 cases. Int J Cardiol 21335.342. 1988 72. Mullins CE, Ludomirsky A, O’Laughlin MP, et al: Balloon valvuloplasty for pulmonic valve stenosis: Two year follow-up hemodynamic and Doppler evaluation. Cathet Cardiovasc Diagn 1476-81.1988 73. Hsieh K, Ou T. Hwang B, et al: Percutaneous balloon
155 pulmonary valvuloplasty in children. Chin Med J [Engl] 391247-254, 1987 74. Mashru MR, Loya YS, Sharma S: Percutaneous balloon valvuloplasty for pulmonary valve stenosis using single or double balloon technique. J Assoc Physicians India 36:546-550, 1988 75. Schmaltz AA, Bein G, Gravinghoff L. et al: Balloon valvuloplasty of pulmonary stenosis in infants and children: Cooperative study of the German Society of Pediatric Cardiology. Eur Heart J 10:967-971, 1989 76. Ballerini L, Mullins CE, Cifarelli A, et al: Percutaneous balloon valvuloplasty of pulmonary valve stenosis, dysplasia, and residual stenosis after surgical valvotomy after surgical valvotomy for pulmonary atresia with intact ventricular septum: Long-term results. Cathet Cardiovasc Diagn 19:165-169,199O 77. Ng MP, Wong KY, Cheng HK. et al: Percutaneous balloon pulmonary valvuloplasty-the Singapore General Hospital experience. Ann Acad Med 19:54-57. 1990 78. Hsu Y. Lue H, Wang J, et al: Echocardiographic changes following balloon valvuloplasty in valvular pulmanic and aortic stenosis. Acta Paediatr Sin 30:290-297. 1989 79. Yip WCL. Tay JSH, Chan KY. et al: Percutaneous transluminal balloon valvuloplasty: The treatment of choice for congenital valvar pulmonic stenosis. Ann Acad Med l9:58-63. 1990 80. Zacharison MC, Friedberg DZ: Percutaneous pulmonaryvalvuloplasty in children. Wis Med J 9:15-18,199l 81. Latson LA, Cheatham JP, Gumbiner CH, et al: Percutaneous valvuloplasty for congenital pulmonary valve stenosis. Nebr Med J 70:76-79, 1985 82. Sutton TM, Carlson R, Bayron H. et al: Balloon pulmonary valvuloplasty for treatment of congenital pulmonary stenosis. Wis Med J 85:30-32, 1986 83. Bordsky SJ: Percutaneous balloon angioplasty: Treatment for congenital coarctation of the aorta and congenital valvar pulmonic stenosis. Am J Dis Child 138:851-854.1984 84. Ozme S, Celiker A, Ozkutlu S, et al: Percutaneous transluminal balloon pulmonary valvuloplasty. Turk J Pediatr 32:25-31, 1990 85. Burrows PE. Benson LN, Smallhorn JS, et al: Angiographic features associated with percutaneous balloon valvotomy for pulmonary valve stenosis. Cardiovasc Intervent Radio1 ll:lll-116, 1988 86. Stenberg RG. Fixler DE, Taylor AL, et al: Left ventricular dysfunction due to chronic right ventricular pressure overload: Resolution following percutaneous balloon valvuloplasty for pulmonic stenosis. Am J Med 84:157161,1988 87. McCrindle BW, VACA Registry Investigators: Factors affecting long-term results after balloon pulmonary valvuloplasty. Circulation 84546, 1991 (suppl2) (abstr) 88. Rocchini AP, Beekman MA: Balloon angioplasty in the treatment of pulmonary valve stenosis and coarctation of the aorta. Texas Heart Inst J 13:377-382, 1987 89. Tynan M, Jones 0, Joseph MC, et al: Relief of pulmonary valve stenosis in the first week of life by percutaneous balloon valvuloplasty. Lancet 1:123, 1984 (letter) 90. Zeevi B. Keane JF, Fellows KE. et al: Balloon
156
dilatation of critical pulmonary stenosis in the first week of life. J Am Coil Cardiol 11:821-824, 1988 91. Ali Khan MA, Al Yousef S, Huhta JC, et al: Critical pulmonary valve stenosis in patients less than I year of age: Treatment with percutaneous gradational balloon pulmonaryvalvuloplasty. Am Heart J 117:1008-1114, 1989 92. Qureshi S, Ladusans EJ, Martin RP: Dilatation with progressively larger balloons for severe stenosis of the pulmonary valve presenting in the late neonatal period and early infancy. Br Heart J 62:311-314. 1989 93. Robida A, Parchik D: Perforation of the heart in a newborn with critical valvar pulmonary stenosis during balloon valvuloplasty. Int J Cardiol26:ll I-112, 1990 94. Gordon LS: Neonatal cardiology casebook: Emergency pulmonary balloon valvuloplasty of congenital pulmonary valve stenosis. J Perinatol 10:86-88, 1990 95. Caspi J. Coles JG, Benson LN, et al: Management of neonatal critical pulmonic stenosis in the balloon valvotomy era. Ann Thorac Surg 49:273-278,199O 96. Latson L, Cheatham J, Kugler J, et al: Balloon valvuloplasty in pulmonary valve atresia and critical pulmonary stenosis. J Am Coll Cardiol 15:241A. 1990 (abstr) 97. Ladusans EJ, Qureshi SA, Parsons JM, et al: Balloon dilatation of critical stenosis of the pulmonary valve in neonates. Br Heart J 63:362-367, 1990 98. Pepine CJ, Gessner IH, Feldman RL: Percutaneous balloon valvuloplasty for pulmonic valve stenosis in the adult. Am J Cardiol50:1442-1445, 1983 99. Khalilullah M, Bahl Vy Choudhary A, et al: Pulmonary balloon valvuloplasty for the nonsurgical management of valvar pulmonic stenosis. Indian Heart J 37:150-153, 1985 100. Gibbs JL, Stanley CP, Dickenson DF: Pulmonary balloon valvuloplasty in late adult life. Int J Cardiol 11:237239,1986 101. Al Kasab S. Riberio P, Al Zaibag M: Use of double balloon technique for percutaneous balloon pulmonary valvotomy in adults. Br Heart J 58:136-141, 1987 102. Fawzy ME, Mercer EN, Dunn B: Late results of pulmonary balloon valvuloplasty in adults using double balloon technique. J Interventional Cardiol l:35-42, 198X 103. Al Kasab S, Ribeiro PA, Al Zaibag M. et al: Percutaneous double balloon pulmonaryvalvotomy in adults: One- to two-year follow-up. Am J Cardiol 62:822-825, 1988 104. Feugelman MY, Lewis BS: Pulmonary balloonvalvuloplasty in the seventh decade of life. Isr J Med Sci 24:112-113. 1988 105. Cooke JP, Seward JB, Holmes DR, Jr: Transluminal balloon valvotomy for pulmonic stenosis in an adult. Mayo Clin Proc 62:306-311,1987 106. Shuck JW, McCormick DJ. Cohen IS, et al: Percutaneous balloon valvuloplasty of the pulmonary valve: Role of right-to-left shunt through a patent foramen ovale. J Am Coll Cardiol4:132-135, 1984 107. Lo RNS, Lau KC, Leung MP: Complete heart block after balloon dilatation of congenital pulmonary stenosis. Br Heart J 59:384-386.1988 108. Fellows KE, Radtke W. Keane JF, et al: Acute complications of catheter therapy for congenital heart disease. Am J Cardiol60:679-683, 1987 109. Weinhaus L, Lababidi Z: Catheter rupture during balloon valvuloplasty. Am Heart J 113:1035-1036. 1987
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110. Attia I, Weinhaus L, Walls JT, et al: Rupture 01 tricuspid valve papillary muscle during balloon pulmonary valvuloplasty. Am Heart J 113:1233-1234, 19X7 111. Burrows PE. Benson LN. Moes F, et al: Pulmonary artery tears following balloon valvotomy for pulmonary stenosis. Cardiovasc Intervent Radio1 12:38-42,199l 112. Karla GS. Wander G. Anand IS: Right-side endocarditis after balloon dilatation of the pulmonary valve. Br Heart J 63:36X-369, 1990 113. Ben-Shachar G, Cohen MH, Sivakoff MC, et al: Development of infundibular obstruction after percutancous pulmonary balloon valvuloplasty. J Am Coil Cardiol 5~754-756, 1985 114. Martin GR, Stanger P: Transient prolongation of the QTc interval after balloon valvuloplasty and angioplasty in children. Am J Cardiol58:1233-1235. 1986 115. Levine JH, Guarmieri T. Kadish AH. et al: Changes in the myocardial repolarization in patients undergoing balloon valvuloplasty for congenital pulmonary stenosis: Evidence for contraction excitation on feedback in humans. Circulation 77:70-77. lY88 116. Kan JS. White RI, Jr. Mitchell SE. et al: Treatment of restenosis of coarctation by percutaneous transluminal angioplasty. Circulation 6X:1087-1094, lYX3 117. Suarez de Lezo J. Fernandez R. Sancho M. el
Treatment of Pulmonary Obstruction: A Review P. Syamasundar
P
ULMONARY STENOSIS can occur as an isolated congenital cardiac defect or in association with other congenital cardiac abnormalities. The pulmonary outflow obstruction is most commonly located at the pulmonary valve level, although it can be subvalvar or supravalvar. The treatment approach has been surgical relief of the stenosis by direct enlargement of the constricted area, especially for isolated obstructions, or bypass of the obstruction by systemic-to-pulmonary artery anastomosis if total surgical correction is not feasible. Since the description by Kan and associates’ of the application of balloon dilatation techniques in children, we and others have used the technique to relieve congenital and acquired obstructive lesions in infants and children. The role of balloon dilation and other transcatheter techniques in the management of pulmonary outflow tract obstruction will be examined in this review. Our personal experience with this technique’-I3 and that reported in the literature will be used as supportive material. For the purpose of presentation, the case material will be divided into the following groups: (1) isolated valvar pulmonary stenosis, (2) supravalvar pulmanic stenosis, (3) pulmonary stenosis with interatrial right-to-left shunt, (4) pulmonary stenosis with ventricular right-to-left shunts, (5) narrowed systemic-to-pulmonary artery shunts, and (6) pulmonary atresia. Branch pulmonary artery stenosis will not be discussed in this review. ISOLATED
PULMONARY
VALVE
STENOSIS
Valvular pulmonary stenosis constitutes 7.5% to 9.0% of all congenital heart defects.24J5 The pathological features of pulmonary stenosis vary,26-2Rbut the most commonly found pathology is what is described as “dome-shaped” pulmonary valve. The “fused” pulmonary valve leaflets protrude from their attachment into the pulmonary artery as a conical or dome-shaped structure. The size of the orifice of the pulmonary valve may vary from a pinhole to several millimeters, most commonly central in location but can be eccentric. Raphae, presumably repreProgress
in Cardiovascular
Diseases,
Vol XXXV,
No 2 (September/October),
Outflow Tract
Rao
senting fused valve leaflet commissures, extend from the stenotic valve orifice to a varying extent down into the base of the dome-shaped valve. The number of raphae vary from none to seven. Children with pulmonic stenosis usually present with asymptomatic murmurs although they can present with signs of systemic venous congestion (usually interpreted as congestive heart failure) due to severe right ventricular dysfunction. Clinical findings of an ejection systolic click and ejection systolic murmur at the left upper sternal border, right ventricular hypertrophy on an electrocardiogram, prominent main pulmonary artery segment on a chest roentgenogram, and increased Doppler flow velocity in the main pulmonary artery are characteristic for this anomaly. When the pulmonary valvar obstruction is moderate to severe, relief of the obstruction is recommended to treat symptoms, if present, or to prevent right ventricular fibrosis and dysfunction. Until recently, surgical valvotomy was the only treatment available, but at the present time, relief of pulmonary valve obstruction can be accomplished by balloon valvuloplasty. Rubio-Alvarez and Limon-LasonZ9,“’ in the early 1950s described a technique by which pulmonic valve stenosis could be relieved via a catheter; they used a ureteral catheter with a wire. Twenty-five years later, Semb and associates3i used a Berman balloon angiographic catheter to produce rupture of the pulmonary valve (commissures); they withdrew an inflated balloon from the main pulmonary artery to the right ventricle and reduced the pulmonary valve
From the Department of Pediatrics, Division of Pediatric Cardiology, University of Wisconsin Medical School, Madison, WI. Supported in part by a grant ffom Oscar Rennobohm Foundation, Inc., Madison, WI. Address reprint requests to P. Syamasundar Rao, MD, Professor and Head, Division of Pediatric Cardioiogy, H41416 CSC, University of Wisconsin Children’s Hospital. 600 Highland Ave, Madison, WI 53792-4108. Copyright 0 1992 by W. B. Saunders Company 0033.0620/9213502-0003$5.0010 1992:
pp 119-158
119
120
gradient. More recently, Kan and associates’ used a static dilatation technique (similar to that used by Dotter and Judkins3? and Gruntzig and his associates33,34) in which they introduced a deflated balloon across the pulmonic valve and inflated the balloon; the radial forces of balloon inflation produced relief of pulmonary valve obstruction. This static dilatation technique is what is currently used. Indications
By and large, the indications for balloon dilatation of pulmonic stenosis are essentially the same as those used for surgical intervention. The indications for surgical pulmonary valvotomy are reasonably clear; patients with a moderate to severe degree of stenosis irrespective of the symptoms are candidates for surgical relief of the obstruction.35s36 The indications for balloon valvuloplasty appear less clear and are rarely defined. In 1988, careful examination’l of all studies available at that time showed that many patients with what may be considered mild pulmonic stenosis (natural history study definition3? gradient < 2.5 mm Hg, trivial; 25 to 49 mm Hg, mild; 50 to 79 mm Hg, moderate; and 2 80 mm Hg, severe) underwent balloon valvuloplasty. Review of the results of balloon valvuloplasty in these patients with mild stenosis showed that 59 patients from 11 studies underwent the procedure for a peak pulmonary valve gradient less than 50 mm Hg.” The peak-to-peak systolic pressure gradient across the pulmonary valve was reduced from 38 ? 6 mm Hg (mean + SD) to 20 ? 11 mm Hg (P < .Ol) immediately after valvuloplasty, as was the right ventricular peak systolic pressure (60 -+ 9 v 43 k 11 mm Hg P < .Ol). At fo,llow-up several months following balloon valvuloplasty, the pulmonary valve gradients (24 ? 12 mm Hg) and the right ventricular pressure (45 + 12 mm Hg) remained improved (P < .Ol) when compared with prevalvuloplasty values. These data indicate there was a statistically significant reduction in pulmonary valvar gradients even in patients with mild pulmonary stenosis. However, the mean residual right ventricular peak systolic pressure at follow-up was 75% of prevalvuloplasty measurements. The question to be asked is whether this modest reduction in the right ventricular pressure is
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worth the risk, morbidity, and expense associated with cardiac catheterization and balloon pulmonary valvuloplasty? The answer (my answer) is “no,” especially in view of a benign natural course of the disease process”h-jO; mild pulmonary stenosis remains mild on follow-up. Therefore, the advisability of balloon valvuloplasty for mild obstruction can be questioned. The recommendations” are to consider the indications for balloon valvuloplasty to be the same as those used for surgical valvotomy and that balloon dilatation should not be performed in patients with gradients less than 50 mm Hg. Because noninvasive Doppler estimates of pulmonary valve gradients are reasonably accurate,41-44 patients with mild stenosis can be followed, and once the Doppler estimate of the gradient is in excess of 50 mm Hg, they can undergo balloon valvuloplasty. Although there is some wisdom in using valve areas for setting criteria for intervention, gradients are adequate for the pulmonary valve provided cardiac indices are measured during prevalvuloplasty catheterization and are shown to be within the normal range. Some investigators4j suggested that balloon valvuloplasty should not be performed in severe stenosis if the peak systolic pressure in the right ventricle is approximately twice that in the left ventricle. Although their concern is understandable, balloon valvuloplasty can be performed safely (see Technique. Appendix 1) in such patients. There were sixteen patients of a total of 71 infants and children46 who had right ventricular pressures approximately twice that in the left ventricle in whom we were able to successfully perform balloon valvuloplasty. Some investigators consider dysplastic pulmonary valves as a relative contraindication for balloon valvuloplasty, 47*48but based on results of others49.s0 and our data,iO balloon valvuloplasty is the initial treatment of choice; perhaps, large balloons to produce balloon/annulus ratios of 1.4 to 1.5 should be used.]” Our experience’.” and that in the Registry’ indicate that the procedure is also successful in patients with Noonan’s syndrome. Patients whose pulmonary valves restenosed following a previous surgical pulmonary valvotomy also respond favorably to balloon pulmonary valvuloplasty. In conclusion, moderate to severe valvar pulmonic stenosis
CATHETER
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STENOSIS
121
(gradient 2 50 mm Hg) irrespective of previous surgical intervention and pulmonary valve dysplasia is an indication for percutaneous balloon pulmonary valvuloplasty. The technique of balloon valvuloplasty is described in Appendix 1. Acute Results
Since the description of balloon pulmonary valvuloplasty by Kan and associates,’ several pediatric cardiology centers across the world Most have used this technique. 2 ..1,45,48-50,53,55,5X,60-84 groups
of investigators,45.49,5~,5~,S5.58,60-~4 includ-
ave reported excellent immediate relief of pulmonic valve obstruction following balloon valvuloplasty. From our group, 73 infants and children, aged 2 days to 20 years (median, 5 years), underwent balloon dilatation of valvar pulmonic stenosis* during a 7 year 8 month period ending May 1991.46 Following valvuloplasty, the peak systolic pressure in the right ventricle decreased (108 rf: 41 (mean -+ SD) v 53 + 22 mm Hg, P < .OOl) as did the peak systolic gradient across the pulmonic valve (91 + 41 v 26 k 19 mm Hg, P < .OOl) (Fig 1). The pulmonary artery pressure (17 + 5 v 23 + 6 mm Hg, P < .OOl) increased. The cardiac index did not change (P > .l). Width of the jet of the contrast material through the pulmonary valve as visualized in the cineangiograms (Fig 2) increased. Less doming and much more “free” movement of the pulmonary valve 1eafletP occurred following the valvuloplasty in each case. Improvement of right ventricular function and a decrease in right-to-left atria1 shunting”’ also occurred. Though not studied by us, improvement in the function of the left ventricleXh is expected. Surgical intervention is avoided in all our cases. Most patients are discharged home within 24 to 48 hours following the procedure. ing
ours,2,3.7,13,15.?1,46
h
Follow- Up Results
Several investigators49J”Js,h5-C8*70,71,7.5 recatheterized 6 to 53 patients, 1 week to 18 months
*Balloon pulmonary valvuloplasty was performed at King Faisal Specialist Hospital and Research Center, Riyadh, Saudia Arabia (1983-1987) and at University of Wisconsin Hospital and Clinics, Madison, WI (1987-1991) and will be referred to as the Madison experience throughout the manuscript.
Fig 1. Bar graph showing acute results of balloon pulmonary valvuloplasty in 73 patients showing a significant (P < .OOl) decrease in the peak-to-peak systolic pressure gradient across the pulmonic valve and peak systolic pressures in the right ventricle. Also, note a significant (P < ,001) increase in the peak systolic pressure in the pulmonary artery.
(mean) following balloon valvuloplasty and reported significant residual gradients ( > 30 mm Hg) in 14% to 100% of patients (Table 1). We recatheterized 45 children 6 to 34 months (mean, 11.0 months) following balloon valvuloplasty. For the group of children in whom follow-up catheterization data were available, the peak systolic pressure gradient across the pulmonic valve (92 & 43 v 29 +- 23 mm Hg, P .: .OOl) and the peak systolic pressure in the right ventricle (109 f 41 v 56 + 22 mm Hg, P < .OOl) decreased immediately after balloon dilatation. The cardiac index (3.3 ? 0.9 1~3.2 -+ 0.7 L/mini ml, P > .l) remained unchanged. On followup, approximately 11 months later, systolic pressure gradient across the pulmonic valve (29 + 23 mm Hg, P < .OOl) remained improved when compared with the predilatation value (Fig 3). The cardiac index (3.5 * 0.8 L/minim’) did not significantly (P > .l) change. Despite improvement as a group, several children had significant residual gradients (Fig 4) across the pulmonic valve, hereafter referred to as restenosis. Nine out of 45 children that were restudied had pulmonary valve gradients in excess of 30 mm Hg. Six of these children underwent repeat balloon valvuloplasty with larger balloons (Fig 6) and the pulmonary valve gradients were reduced from 96 * 40 to 40 ? 22 mm Hg (P < .Ol). The other 3 children with residual gradients of 45, 50, and 60 mm Hg are being followed clinically. Repeat follow-up catheterization (in 4) or Doppler studies (in 4) were available in 8 children (24 months after the first
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Fig 2. Selected cineangiographic frames from a “sittingup” view (40” cranial and 15” left anterior oblique) of a right ventricular angiogram before (A) and 15 minutes (B) following balloon pulmonary valvuloplasty. The thin jet of passage of contrast across the pulmonic valve (arrows) in A has markedly increased (arrows) in E.
Doppler follow-up data are available, ie, a 14% recurrence rate. In the recently compiled Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry data,87 suboptimal longterm results, defined as the need for surgery or repeat balloon valvuloplasty or a pulmonary valve gradient in excess of 36 mm Hg, was noted in 89 of 433 (21%) patients who had a follow-up at a median interval of 31 months after balloon valvuloplasty. Thus, the Madison data compare favorably with the VACA Registry data from 17 institutions. Apart from pressure gradient relief, there are
balloon valvuloplasty) and the residual pulmonary valve gradients were 28 ? 12 mm Hg. The restenosis rate (9 of 45, 20%) in the Madison group, though high, is comparable with the 14% to 100% rate reported by other workers (Table 1). However, it should be noted that we initially recommended recatheterization 6 to 12 months following valvuloplasty, but more recently, routine postoperative catheterization is not recommended unless the Doppler estimate of the residual gradient is high. Therefore, it is concluded that restenosis occurred in 9 of 63 patients in whom catheterization and/or Table
1. Intermediate-Term
Follow-Up Number
Author
and Year
Kan et al, 1984
Patients Undergoing BPV
20
of
Catheterization Numberof Patients With Follow-Up 11
Results
of Balloon
Pulmonary
Valvuloplasty
MC?atl (Range). Months
7 (2-12)
Poor Result* on Follow-Up, No. (%I
Comments
2 (18)
The failure
2 (33) 7 (IOOH
value or after previous Brock Both patients underwent surgery Repeat BPV in one patient with 52 mm Hg
27 19
6 7
- (2-6) 12 (9-13)
Miller,
16
7
4 (3-6)
l(14)
23
12
5.5 (0.25-6)
6 (50)
gradient
Sullivan
et al, 1985 et al, 1986
32
Shrivastava et al, 1987 Rey et al, 1988
32 51
Fontes et al, 1988 Schmaltz et al, 1989
Rao,
1991
Abbreviation: *Poor result tThe *Poor
14 21 23
2 (14) 9 (43) 5 (22) 10 (23) 14 (26)$
100
44
273
53
12 (3-14) ll-
73
45
11 (6-34)
BPV, balloon pulmonaryvalvuloplasty. is defined as pulmonary valve gradient
pulmonary valve result is defined
10 (6-14) - (3-18) -(l-17)
in excess
9
with
reduction
BPV with excellent Repeat valvuloplasty
Repeat tory
with
dysplastic
to 34 mm Hg
results in four
patients
with
results
BPV in five patients results
with
satisfac-
Repeat BPV in 14 patients; successful In IO. remaining 4 with dysplastic valves required surgery
(20)
Repeat
of 30 mm Hg at follow-up.
gradient ranged between 31 and 52 mm Hg with a mean as gradient ~40 mm Hg.
was in patients
Two patients with gradients of 24 and 22 mm Hg at follow-up underwent repeat
good Khan
the Literature
Duration of Follow-Up
Tynan et al, 1985 Kveselis et al, 1985 1985
From
of 38 mm Hg.
BPV in 6 patients
with
good
results
CATHETER
THERAPY
OF PULMONARY
STENOSIS
123
16Or Mean
Post
+ SD N = 45
FU
acute and follow-up results of the Fig 3. Bar graph showing 45 unselected patients (from among 73 patients undergoing balloon valvuloplasty-Fig 2) who underwent cardiac catheterization 11 months (mean) following balloon pulmonary valvuloplasty. Note significant (P c 0.001) decrease in the peak systolic pressure gradient across the pulmonary valve immediately after the procedure that remained unchanged (f > .l) at follow-up; the later continues to be significantly (P < .OOl) lower than the prevalvuloplasty gradient. The gradients represented are valvar gradients without any regard to infundibular gradients.
other benefits. Right-to-left interatrial shunting that was present before valvuloplasty has completely disappeared in most patients.20 Right ventricular dysfunction and tricuspid insufficiency improved. Figures 5 and 6 illustrate improvement in cardiac size and tricuspid insufficiency following balloon valvuloplasty. W&4,7.15 and otherS52,66,72.78,87,88 have previ-
ously reported echo-Doppler follow-up studies after balloon valvuloplasty. Kveseli@ reported results of Doppler examination in 11 patients 15 -+ 19 months following valvuloplasty; calcu-
I
. cam
.
0 P,P BP”
Post BP”
FU
Repd BP”
Second FU
Fig 4. Sequential pulmonary valvar gradients are shown for each of the nine patients who had gradients in excess of 30 mm Hg at follow-up catheterization. Repeat balloon dilatation at the time of follow-up (FU) catheterization in six of these children produced decreases in the gradient in each patient. At a second follow-up study (catheterization or Doppler), the gradients remained low. Solid circles, gradients measured at cardiac catheterization; open circles, Doppler estimated peak instantaneous gradients.”
I
lated right ventricular outflow gradient was reduced from 86 +- 29 to 38 + 9 mm Hg immediately after valvuloplasty, which decreased, though, to an insignificant degree, to 33 & 7 mm Hg, at follow-up. Doppler evidence for pulmonary insufficiency was present in 8 of 11 patients. Similar improvement was noted in a subsequent publications8 involving 28 patients with successful valvuloplasty. Robertson et al,“2 while analyzing the morphology of the right ventricular outflow tract following balloon valvuloplasty, reported follow-up (10.2 + 5.6 months) Doppler studies in 18 patients. The calculated pulmonary valvar gradient having been reduced to 37 ? 23 from 72 2 31 mm Hg immediately following valvuloplasty, decreased further to 31 2 21 mm Hg at follow-up. Mullins et alT2 obtained continuous-wave Doppler flow measurements in 30 children (of 63 children who underwent balloon pulmonary valvuloplasty) at a mean of 13 months following valvuloplasty; the estimated residual gradient was 20 & 8 mm mEcho-Doppler follow-up studies in 63 children 3 to 36 months (1.5 ? 6 months) following valvuloplasty were available from the Madison group. Two D-derived, M-mode tracings of the right ventricle and left ventricle and pulsed- and continuous-wave Doppler flow velocity recordings from the right ventricular outflow tract and the main pulmonary artery were recorded, as previously reported,4,7+4Zinitially, at 3- to 6-month intervals, and subsequently, at 1Zmonth intervals. The pulmonary valvar gradient was calculated using a modified Bernoulli equation (gradient = 4 V22, where V2 is peak Doppler flow velocity in the main pulmonary artery). When the right ventricular outflow tract Doppler flow velocity (V,) was in excess of 1.0 m/s, Vr was incorporated into the Bernoulli equation [gradient = 4 (V22 - Vr2)]. The echo-Doppler results were analyzed separately for the group with good results (group I) and for the group with poor results (group 11). In the group of patients with good results, the right ventricular enddiastolic dimension decreased, but not significantly (P > .05), from 18.3 2 5.6 to 16.2 ? 5.3 mm immediately after valvuloplasty, which decreased further to 15.4 f 5.0 mm (P < .Ol) at the last available follow-up (Fig 7). The left ventricular end-diastolic dimension did not
124
P. SYAMASUNDAR
RAO
Fig 5. Posteroanterior view of a chest roentgenogram showing cardiomegaly (A) before balloon pulmonary valvuloplasty. The cardiomegaly has improved on a chest x-ray taken 1 year following balloon valvuloplasty (B).
change immediately following valvuloplasty (30.8 ‘-+ 8.3 v 29.6 + 7.8 mm, P > .l), but at follow-up, there was a significant increase (34.1 + 8.1 mm, P < -02) (Fig 8). The Doppler flow velocity in the main pulmonary artery decreased (P < .OOl) from 4.3 2 0.8 to 2.8 I 0.64 m/s immediately following valvuloplasty, which, on follow-up, was 2.4 2 0.6 m/s (P < .OOl) (Fig 9); when pressure gradients were calculated, these values respectively corresponded to 77 ? 29 (pre), 31 -+ 15 (post), and 24 ? 12 mm Hg (at follow-up). An example is shown in Fig 10. Doppler evidence for mild pulmonary insufficiency was present in 50 of 54 patients in whom data was available. Longitudinal, follow-up, Doppler flow velocities in the pulmonary artery are shown in Fig 11. These data show that there is rapid reduction of flow velocities immediately following valvuloplasty with further reduction at 6 months follow-up. Subsequently, there was minimal reduction, if any.
Fig 6. Posteroanterior views of the right ventricular (RV) cineangiogram before (A) and 1 year following (B) balloon pulmonary valvuloplasty. Note disappearance of tricuspid insufficiency at follow-up (B). The right ventricular cineangiograms correspond to A and B of Fig 7. C, catheter, PA, pulmonary artery; RA, right atrium.
By contrast, in the group of patients with poor results (group II), the right ventricular enddiastolic dimension (21.0 2 9.4 mm) did not change (P > .i) either immediately after valvuloplasty (21.0 +- 10.6 mm) or at follow-up (21.0 * 12.7 mm) (Fig 7). Similarly, left ventricular end-diastolic dimension (27.0 zt 6.7 mm) did not change (P > .l) immediately following (30.8 + 10.8 mm) or several months after valvuloplasty (26.1 f 5.6 mm) (Fig 8). Peak Doppler flow velocity in the pulmonary artery before valvuloplasty was 4.1 2 0.7 m/s, which remained essentially unchanged (P > .05) after valvuloplasty (3.5 rf 0.5) and on follow-up (4.0 * 0.6) (Fig 12). Doppler evidence for pulmonary insufficiency was present in two of the nine patients on follow-up. Six of the nine patients with poor results underwent repeat valvuloplasty; 7 to 12 months following repeat valvuloplasty the Doppler flow velocity decreased to 2.5 2 0.4 m/s (P < .OOl) (Fig 12). Based on these data, the intermediate-term
CATHETER
THERAPY
OF PULMONARY
STENOSIS
P’O.1
I I ” T
TI
T
PRE Group
I
Group
follow-up results appear encouraging and balloon valvuloplasty is recommended as a procedure of choice for treatment of isolated valvar pulmonic stenosis. Further refinement of the catheter technology and a better understanding of the use of balloon catheters with appropriate choices for specific situations may decrease or abolish the recurrence rate. Despite these good results, much longer-term (10 years) follow-up data are necessary to further confirm long-term effectiveness of balloon pulmonary valvuloplasty for relief of valvar pulmonic stenosis. Applicability To All Age Groups
Although balloon pulmonary valvuloplasty is used most frequently in children, it has
5 1
So
f
40
1
PbO.1 Mean
l
So
Iprg.l
7c-l
t
I
:
T
T
Group
I
Group
FU
PRE
IMM
FU
’
Fig 9. Peak Doppler flow velocities across the pulmonic valve before (PRE), immediately after (IMM) pulmonary valvuloplasty, and at follow-up (FU) are shown on the left-hand panel, whereas peak instantaneous Doppler-calculated gradients are shown in the right-hand panel for the group of patients with good results. Note significant (P c ,001) decreases in Doppler velocities and gradients immediately after valvuloplasty. There was further decrease (P < .Ol to c .02) at follow-up, presumably related to resolution of infundibular obstruction.
II
Fig 7. Right ventricular end-diastolic dimensions before (PRE) valvuloplasty, immediately after (IMM) valvuloplasty, and at follow-up (FU). Note that there was an insignificant (P > .05) decrease in RV size immediately after valvuloplasty, which diminished significantly (P c .Ol) at follow-up in the group I good-result patients, whereas no change (P > .l) was noted in the group II poor-result patients.
p~o.02
IMM
II
Fig 8. Similar to Fig 7 but left ventricular end-diastolic dimensions are shown. Note that there was no change immediately after valvuloplasty but a significant (P c ,021 increase was observed at follow-up in group I good-result patients. No change (P > .l) was noted in the group II with poor results.
also been used in neonatesh,“0,49.-5’.8y-y7 and in adults~65,68,71.74.98-106
Neonates. The experience with balloon pulmonary valvuloplasty in the neonate with critical pulmonary stenosis is limited and the series with largest numbers contain 5,90 8.49 and 1195,97 patients (Table 2). The procedure is more technically difficult but can be accomplished by the use of end-hole balloon-wedge catheters, small-sized, high-torque guide wires, low-profile balloon catheters, and progressive dilatation starting with small balloons. The pulmonary outflow tract occlusion during valvuloplasty is well tolerated if combined with continuous administration of prostaglandins to maintain ductal patency. Once the ductus is closed, progressive dilatation of the stenotic pulmonary valveg2 may be of benefit. The complication rateP and failure rates to accomplish balloon valvuloplasty are higher than those observed with older children. The overall result is also perhaps not as favorable as in children. Right ventricular hypoplasia, severe infundibular obstruction, pulmonary valve ring hypoplasia, and pulmonary valve dysplasia all tend to adversely affect the results of valvuloplasty in the neonate with critical pulmonary stenosis. Adults. Relief of pulmonary stenosis in adult patients has been accomplished by balloon valvuloplasty.65,6R,71.74.98-3*6 Because of the physical size of the pulmonary valve ring, many of them may require balloon valvuloplasty using two
flow Fig 10. Doppler pulmonary valvuloplasty. with permission.“)
velocities across Note significant
the pulmonic valve in a patient before, decrease in the velocity both immediately
balloons.101J02 However, as pointed out elsewhere,8J4 double-balloon technique is comparable to, but not superior to, single-balloon technique when equivalent balloon/annulus ratios are compared. Acute results (Table 3) of balloon valvuloplasty9*-lo6 are similar to those reported in children. Successful results have been documented even in the sixth and seventh decades of life.100J04J05 Based on our own experience with teenagers7,16 and that of others in adult patients ,98~101~103 infundibular obstruction following balloon valvuloplasty appears to be more common in older patients than in young patients. The reason for this is probably longstand-
on the day following, after valvuloplasty
and 8 months and at follow-up.
after balloon (Reprinted
ing right ventricular hypertension and consequent right ventricular hypertrophy in older patients. Follow-up results (Table 3) though documented in few studies102J0j do indicate persistent relief after a mean follow-up of 1 to 2 years. In summary, it appears that successful balloon valvuloplasty is feasible in all age groups. Complications Acute. Complications during and immediately after balloon pulmonary valvuloplasty have been remarkably minimal. Transient bradycardia, premature beats, and a decrease in systemic pressure during balloon inflation have been uniformly noted by all workers, particularly with valvar dilatations. These return rapidly back to normal following balloon deflation. Systemic hypotension may be minimal during balloon inflation in the presence of a patent foramen 5
PRE N=62
MM 3 N=SO N=27
Months
6 N=35
12 N=35
Following
16 N-15
24 N=12
30 N=6
36 N=5
42 N=4
Valvuloplasty
Fig 11. Peak Doppler flow velocities in the main pulmonary artery before (PRE) and immediately after (IMM) balloon valvuloplasty, and at follow-up are shown. N indicates the number of patients in whom the data were available at that particular interval. Note that a decrease in the flow velocity occurred immediately after valvuloplasty with further reduction at a E-month follow-up. There was minimal, if any, change subsequent to E-month follow-up. *indicates P < .Ol when compared with prevalvuloplasty values. tindicates P < .05 when compared with immediate postvalvuloplastyvalues. SD, standard deviation.
’
PRE
IMM
FU
FURI
PRE
MM
FU
FURI
Fig 12. Doppler flow velocity and instantaneous Doppler gradients across the pulmonic valve in the group II children with poor results. Note that there was no decrease in the gradient either immediately after (IMM) or at follow-up (FU). Repeat balloon valvuloplasty has resulted in decrease in gradients (P < .OOl). FURI, follow-up after reintervention.
CATHETER
THERAPY
Author
OF PULMONARY
STENOSIS
Table
of Balloon
2. Results
Number of Patients Undergoing BPV
and Year
Rey et al, 1988
127
Pulmonary
Valvuloplasty
Pulmonary Valve Gradient (mean ? SD),mm Hg Pre
8
107
+ 22
Post
FU
59 k 90
25 k 10
in Neonates
From
FU No/Duration
P00r Result No. (%I
Al-17
mo
the Literature
2 (25)
Comments Pressure nates
data were from 8 neoand 11 infants i 1 .O yr.
Repeat valvuloplasty neonates. Zeevi
et al. 1988
All Khan
5
et al,
123
4
t- 7*
59 + 8*
61 +45
6+
10
35+27
5lllmo
1 (20)
69 -c 47
318 mo
2 (66)
Pre-and peak Repeat dren
1989 Qureshi
et al, 1989
3
125,135*
15,ot
218 mo
13.16
post-pressures were RV systolic pressures. valvuloplasty in 2 chilreduced
et al, 1990
Ladusans
et al,
ll$
68 + 4
20 2 4
11s
(mean f SEM) 87 i 30
(mean + SEM) 33 s 28
-
0 (0)
11119mo
gradient
to 10
and 30 mm Hg. respectively. One patient died after unsuccessful tation.
Caspi
in both
-
attempt
at balloon
dila-
FU results were not given but stated to be not changed.
39 i 23
10122
mo
4 (40)
One patient died BPV, 4 patients
25 2 32
3114
mo
1 (33)
Repeat balloon valvuloplasty reduced gradient from 61 to 18
1990
7 days after required repeat
intervention. Rao et al, 1991
3
69 2 50
11 + 11
mm Hg. NOTE.
Single
case
Abbreviations: *Right ventricular
reports
and abstracts
are not included.
BPV, balloon pulmonary valvuloplasty; peak systolic pressures.
FU, follow-up;
RV, right
ventricular.
tlnfundibular *Attempts
gradient for balloon
was 100, which subsequently disappeared. valvuloplasty were made in 20 patients; the procedure
was accomplished
in 11 neonates.
OAttempts
for balloon
valvuloplasty
was accomplished
in 11 neonates.
Table
were
3. Results
Number of Patients Undergoing Author
Pepine
and Year
et al, 1982
made
in 15 patients;
of Balloon
the prodecure
Pulmonary
Valvuloplasty
BPV
Pre
Post
1
140 83,70 30
30,24 32
107 95
52 25
36
105 93 2 22
13 26 f 12
-
70 + 28 260
10 2 3 90 32% 14
Kan et al, 1984 Shuck et al, 1984
2 1
Khalilulah
1
in Adults
Pulmonary Value Gradient (mean 2 SD),mm Hg FU No/Duration
FU
42
38
l/IO
22,-
days
From
PCW FkSUlt* No. (O/o)
Comments
1 (100)
lnfundibular
-
Gradients higher
I/1/14days
2
the Literature
post, Gibbs
et al., 1985 et al., 1986
Cooke et al, 1987 Al Kasab et al, 1988 Mashru et al. 1988 Flugelman et al, 1988 Frawzy et al, 1988
1 1 21 3 1 18
105 2 30
and
FU. respectively) -
Only clinical No follow-up
90 11
14117
mo
5 (36)
113 wks lll6mo
follow-up
Double balloon No follow-up
in all patients. -
1 (100) 4 (36)
developed
after exercise were (69, 28, and 20, pre,
1 (100)
1.1 mo
17 2 5 26?
gradient -
Repeat
balloon
valvuloplasty
patients reduced the gradient from 59 and 52, repectively,
in 2 to
24 and 22 mm Hg. NOTE. Shrivastava et aP8 and Fontes et al” reported for adult patients. Abbreviations: BPV, balloon pulmonary valvuloplasty; *Poor
results
is defined
as a residential
pulmonaryvalvar
successful
balloon
valvuloplasty
in adults,
FU, follow-up. gradient
> 30 mm Hg at follow-up.
but the data were
not separately
given
128
ovale because of the right-to-left shunt across it, filling the left ventricle.106 Use of double balloons10r and of a trefoil or a bifoil balloon,b0-h3 to allow blood egress from the ventricle during balloon inflation and shorter periods (5 seconds) of inflation, 8~14have been advocated to reduce the systemic hypotension. After evaluation of each of these techniques, a short period of balloon inflation (5 seconds or less) appears most efficacious without compromising immediate or follow-up results.2i,23 Blood loss requiring transfusion has been reported in many studies. Complete right bundle branch block,90 transient or permanent complete heart block,5”.‘07 cerebrovascular accident,49 loss of consciousness,5’ cardiac arrest,‘08 convulsions,53 balloon rupture at high inflation tricuspid valve papillary muspressures, 49.64*70,109 cle rupture,“O pulmonary artery tears,“’ rightsided endocarditis,‘12 and severe infundibular obstruction requiring propranolol administration7J”J8,49,70.71and/or surgical intervention,70,rr3 though rare, have been reported. Some of these complications may be unavoidable. However, meticulous attention to the details of the technique, use of appropriate length of the balloon, avoidance of extremely high inflation pressures, and use of short inflation/deflation cycles may prevent or reduce the complications. Holter monitoring for 24 hours following balloon valvuloplasty6h showed premature ventricular contractions (grade 1, Lawn criteria) in one third of the 12 patients so studied. It is not clear from this studfe whether the premature beats were present before valvuloplasty and for how long after valvuloplasty the premature beats persisted. Transient prolongation of the QT, interval following balloon angioplasty/valvuloplasty1’4~1r5 may be a potential hazard for developing R-on-T phenomenon in children with ventricular ectopy. The Holler findingP of premature beats following valvuloplasty may have significance in the light of prolongation of the QT, interval.rr4 However, no patients from our series or many other studies have been known to develop ventricular arrhythmias, although two cases of sudden death from ventricular fibrillation shortly after balloon angioplasty of aortic coarctation’lhJr7 were reported. Whether these arrhythmias are related to QT, prolongation or not is
P. SYAMASUNDAR
RAO
not known. However, patient monitoring following balloon valvuloplasty/angioplasty is warranted.l14 Although multiple complications were listed, the VACA Registry reported only a 0.24% death rate and 0.35% major complication rate from the 822 balloon pulmonary valvuloplasty procedures from 26 member institutions” attesting to the safety of the procedure. Complication at follow-up. With regard to complications at intermediate-term follow-up, femoral venous occlusion, pulmonary valve insufficiency, and pulmonary valve restenosis have been noted. Anywhere between 10% to 29%‘J9J’” of femoral veins through which balloon valvuloplasty have been performed were noted to be occluded at follow-up. In the Madison series, 3 of 45 patients (7%) that we restudied following pulmonary valvuloplasty had a blocked femoral vein. It is the consensus that the femoral venous occlusion is more common in small infants.4y~hh~10” Auscultatory evidence for pulmonary valve insufficiency has not been thoroughly scrutinized. Doppler evidence for pulmonary insufhciency appears sensitive but was studied by only Rocchini and a few investigators. 7.52.66.72.78.88 BeekmatP reported pulmonary insufficiency in 31 of 37 (84%) patients, whereas Robertson et aP2 found mild pulmonary insufficiency in all 29 patients studied. When we reviewed this last from our group, 50 of 54 (93%) patients had Doppler-demonstrable pulmonary insufficiency. However, the pulmonary insufficiency is minimal as evidenced by lack of right ventricular volume overloading (normal-sized right ventricle and no paradoxical septal motion) in this group of patients as well as by equilibriumgated radionuclide angiograms reported by Tynan.S3 Although the long-term follow-up studies should be scrutinized for progressive right ventricular volume overloading, the current data suggest that the pulmonary insufficiency produced by balloon vaivuloplasty is unlikely to be problematic. Recurrence of valve stenosis following balloon pulmonary valvuloplasty has been reported by most investigators (Table I), but the reasons for the restenosis at intermediate-term follow-up has been studied only to a limited degree.‘“,S5.65-67.87 W e h ave systematically investigated the cause of recurrence of pulmonic
CATHETER
THERAPY
OF PULMONARY
129
STENOSIS
stenosis following balloon valvuloplasty.12J7 On the basis of results of 6- to 34-month follow-up catheterization data in 40 children, they were divided into group I with good results (pulmonary valve gradient of 30 mm Hg or less), 33 patients; and group II with poor results (gradient greater than 30 mm Hg), seven patients. Fourteen biographical, anatomic, physiological, and technical factors (Table 4) were examined by multivariate logistic regression analysis to identify factors associated with restenosis. The identified risk factors were (1) residual pulmonary valve gradient in excess of 30 mm Hg immediately following balloon valvuloplasty and (2) balloon-to-pulmonary valve annulus ratio less than 1.2. Dysplastic pulmonary valves did not seem to play a role in recurrence and this may have been due to the use of large balloons with dysplastic valves. The influence of these factors on restenosis is examined in Figs 13 and 14. The smaller ballooniannulus ratios are associated with a higher chance for recurrence as are the higher residual gradients immediately following balloon pulmonary valvuloplasty. The data suggested that a balloon/annulus ratio of less than 1.2 is the cause for pulmonary valve restenosis at intermediate-term follow-up, and such recurrences can be predicted in patients with immediate postvalvuloplasty pulmonary valve gradient in excess of 30 mm Hg. ThereTable
4. Variables
Regression Pulmonary
Examined
Analysis Value
by Multivariate
to Identify
Restenosis
Factors
Following
Logistic
Responsible Balloon
for
Valvuloplasty
Age at valvuloplasty Duration of follow-up Pulmonary Pulmonary
valve valve
Right ventricular Angiographic
dysplasia, severe ring hypoplasia
hypoplasia infundibular
peak systolic peak systolic
loplasty Right ventricular
infundibular
loplasty Pulmonary
peak
valve
Advances
and Publishing in Medicine
pressure
B/A
Ratio
1.2 or
BIA
Less
Rati io >1.2
Fig 13. Rates of recurrence of pulmonary valve stenosis after balloon valvuloplasty as it relates to balloon/annulus ratio are shown. Note that the rates of restenosis increase es the balloon/annulus ratio decreases. Percentages are marked within the bars and actual numbers are shown on the top of each bar.
fore, it is suggested that progressively larger balloons be used and reduce the valve gradient to less than 30 mm Hg.12J7J Pulmonary valve dysplasia and pulmonary valve annular hypoplasia may well play a significant role in the recurrence of pulmonary valve obstruction but did not seem to have an adverse effect in our study group, perhaps related to the narrow ranges of such abnormalities in our study group. Recent analysis of the VACA Registry data8’ on 433 patients followed up to a median interval of 31 months also identified balloon/annulus ratio and immediate postvalvuloplasty gradient 2 36 mm Hg as factors predicting a suboptimal follow-up result, very similar to our study.L2J7 In addition, the Registry data analysis identified dysplastic pulmonary valve morphology and age less than 2 years as factors predisposing to recurrence. I
before valvuloplasty gradient before valvugradient
pressure
annulus
reprinted Co., and
Ratio >l.O
“”
gradient
before
valvu-
immediately
ratio
Maximum pressure achieved in the balloon Number of balloon dilatations Total duration of balloon inflation Copyrighted Cardiology
B/A
or mild
pressure pressure
systolic
valve
Ratio
1.0 or Less
stenosis
Right ventricular Pulmonary valve
after valvuloplasty Balloon/pulmonary
B/A
with rhe permission of Clinical Inc., and/or the Foundation to:
Science.15
Pulmonary Gradient
Valve 530
Fig 14. Similar to balloon valvuloplasty ents are used instead rate of recurrence at Hg immediately after
mmHg
Pulmonary Gradient
Valve ~30 mmHg
Fig 13 except that the immediate postpeak-to-peak pulmonary valve gradiof balloon/annulus ratios. Note a higher follow-up when the gradient is >30 mm valvuloplasty.
130
P. SYAMASUNDAR
Table
5. Summary
Patients
With
Author,
of Results
Pulmonary
of Balloon
Valve
No of Patients With DPV
Year
Valvuloplasty
Dysplasia
From
Immediate Success 1%)
in
the Literature Follow-Up Success (%)
Kan et al, 1984 Tynan et al, 1985
1 3
0 (0) 0 (0)
0 K’l
Miller, 1986 Sullivan, et al, 1986
1 2
0 (0) 1 (501
0 (0)
Rocchini 1986
& Beekman, 7
0 (0)
Musewe Di Sessa
et al, 1987 et al, 1987
5 3
1
Rey et al, 1988 Marantz et al, 1988
4 4
Rao et al, 1988 Ballerini et al, 1990
13 9
Total
52
Abbreviation: *Patients calculation
DPV, dysplastic without of percent
follow-up
0 (0)
120)
0 (0) 3 (75)
3 (75)
3 (75) 9 (69)
2 (50) 10 (77)
2 122)
3 (331 22 (47)X
19 (37) pulmonary
were
3 (43) 1 (201
excluded
valves. for the purpose
of
success.
Other Issues L$splastic pulmonary valve. Dysplastic pulmonary valves have been implicated as a cause of failure following balloon pulmonary valvuloMore recently, detailed replasty. 49~s3~55~65-67~88 ports of balloon valvuloplasty in patients with dysplastic pulmonary valves47,48suggested that poor results may be expected with dysplastic pulmonary valves. A summary of experience reported in the literature is tabulated in Table 5. The Madison experience with dysplastic pulmonary valves is contrary to that reported in these articles. Therefore, we previously reviewedI the results of balloon valvuloplasty in 13 patients with dysplastic pulmonary valves from our total experience at that time with 56
RAO
patients to assess outcome in this subgroup. These results were compared with valvuloplasty results of 43 nondysplastic pulmonary valves.“’ Dysplasia of the pulmonary valve was assessed based on the criteria outlined by Jeffery, Koretzky, and their associates.“K.l’” When all criteria, namely (1) angiographic appearance of nodular and uneven thickening and poor doming of the valve leaflets (Fig 15), (2) valve ring hypoplasia (less than mean value for the given body surface area as defined by Rowlatt),‘“l and (3) no poststenotic dilatation, were present, the pulmonary valve was considered dysplastic. When valve leaflets appeared dysplastic without the presence of one or both of the other criteria. the valve was considered mildly dysplastic. A total of 13 dysplastic pulmonary valves were identified; 7 were severely dyspIastic and 6 were mildly dysplastic. Balloon valvuloplasty in 13 patients, aged 6 days to 12 years (median 1 year), with dysplastic pulmonary valves reduced the pulmonary valve gradient from 77.2 & 44.2 to 26.8 +- 17.0 mm Hg (P < .OOl), which remained improved (34.9 +34.6 mm Hg, P < .02) at 6- to 19-month (mean. 10 months) follow-up (Table 6). The results of individual patients are depicted in Fig 16. Valvuloplasty in 43 patients without dysplastic pulmonary valves reduced the valve gradient from 94.3 2 41.0 to 31.1 2 22.4 mm Hg (P < .OOl) immediately following the procedure, which at 6- to 34-month follow-up in 23 patients was 29.2 t 33.5 mm Hg (P < .OOl) (Table 6). The pulmonary valvar gradients (77.2 -+ 44.2 1’94.3 + 41.0 mm Hg) before valvuloplasty. residual
Fig 15. Selected frames from right ventricular (RV) cineangiograms of patients without (A) and with (B) dysplastic pulmonary valves. (A) Thickened and domed pulmonary valve leaflets are noted. Note poststenotic dilatation of the pulmonary artery (PA). (6) Pulmonary valve leaflets are markedly and unevenly thickened without doming. There was no jet formation and no poststenotic dilatation of the PA. The pulmonary valve ring is small when compared with norms described Rowlatt et al.‘*O (Reprinted with permission.lO)
CATHETER
THERAPY
Table
OF PULMONARY
6. Comparison
Dysplastic
of the Group
Pulmonary valve dient prevalvulo-
dient
131
of Patients
Pulmonry Valves With the Group Pulmonary Valve Dysplasia Dysplasia (mean + SD)
plasty, Pulmonary
STENOSIS
With With
No Dysplasia (mean k SD)
No
P Value
gra-
mm Hg valve gra-
77.2
+ 44.2
94.3
* 41 .o
>.I
26.8
2 17.0*
31.1
+ 22.4*
>.l
-c 34.6t
29.2
k 33.5*
>.l
immediately
after valvuloplasty, mm Hg Pulmonary valve gradient at follow-up, mm Hg
34.9
*P < .OOl when
compared
tP < .02 when Reprinted with
compared permission.‘0
with with
prevalvuloplasty prevalvuloplasty
gradient. gradient.
pulmonary valvar gradient (26.8 + 17.0 v 31.1 2 22.4 mm Hg) immediately after valvuloplasty, and residual gradient (34.9 + 34.6 v 29.2 f 33.5 mm Hg) at follow-up catheterization were similar (P > .l) in both groups (Table 6). However, the ballooniannulus ratio used in dysplastic pulmonary valve patients (1.3 2 0.25) was slightly higher than that used in nondysplastic pulmonary valve patients (1.2 + 0.24), although this difference did not attain statistical significance (P > .l). Two of the 13 dysplastic pulmonary valve patients (Fig 16) and three of the 23 nondysplastic pulmonary valve patients required repeat valvuloplasty (P > .l) at fol0) 200 r
I
Pre SPV
Post SPV
FU
Repeat SPV
Second FU
Fig 16. Peak-to-peak pulmonary valve systolic pressure gradients in 13 patients with dysplastic pulmonary valves are shown. Note significant decrease in pressure gradient immadiately after balloon pulmonary valvuloplasty (BPV) in all patients. Gradient in excess of 30 mm Hg was present in four patients. At follow-up (FU) study, gradients remained low or decreased further in 10 patients (solid lines), whereas gradient increased in three patients (broken lines). Two of these children underwent repeat valvuloplasty with larger balloons at follow-up study with resultant decrease in gradients. One of these children underwent a second follow-up study and the residual gradient was low. (Reprinted with permission.9
low-up catheterization. Residual pulmonary valvar gradients in excess of 30 mm Hg at follow-up were present in 3 of the 13 and 4 of the 23 (P > .l) patients, respectively, with and without dysplastic valves. When all valvuloplasties were divided into those with good results (gradient I 30 mm Hg at follow-up), 29 patients, and those with poor results (gradient > 30 mm Hg at follow-up), 7 patients, the prevalence of dysplastic pulmonary valves, respectively, in these two groups was ten and three and was similar (Z’ > .l). In ten patients with dysplastic pulmonary valves with good results, the ballooniannulus ratio (1.37 + 0.22) used for valvuloplasty was larger (P < .Ol) than that (1.04 2 0.17) used in three patients with poor results. These data suggest that (1) the results of balloon valvuloplasty in patients with dysplastic valves are comparable to those without, (2) the dysplastic valves were not responsible for recurrence of valve stenosis, and (3) use of large balloons in patients with dysplastic valves may have reduced the chance for recurrence.1o Marantz et a150 compared immediate and follow-up results of balloon valvuloplasty in four patients with dysplastic pulmonary valves with those of 32 patients without dysplastic valves and concluded that significant palliation or relief of gradient occurred following valvuloplasty and suggested that dysplastic pulmonary valves should not be excluded from an attempt at balloon valvuloplasty. In the VACA Registry study,s7 examining the causes of suboptimal follow-up result, dysplastic valve morphology was identified as one of the factors predisposing to poor outcome. However, this group included complex pulmonary stenosis (for example, tetralogy of Fallot). The reason for the discrepancy between different studies10~47~48~50~87 in the results of valvuloplasty in patients with dysplastic pulmonary valves is not clear; it may be related to interpretation of clinical and angiographic data in labeling a given patient as having dysplastic pulmonary valves, it may be related to variable degrees of pulmonary valve dysplasia,47,121.12’ or presence of commissural fusion mixed with dysplasia.47.4x,121It is generally considered that splitting of commissural fusion123 is one of the major mechanisms of relief of valvar stenosis by bal-
P. SYAMASUNDAR
132
loon dilatation. Therefore, it is somewhat surprising that some patients with dysplastic valves would have good results. However, variability of the extent of dysplasia and dysplasia mixed with commissural fusion47.48.119,121,122 can to some extent explain these results. Musewe et al47 suggested that if echocardiographic features of commissural fusion are present, catheterization and angiography should be performed to confirm commissural fusion, and if so, balloon valvuloplasty should be performed. We agree with this approach. However, based on these resultslo and those observed by Marantz et aLso we would recommend balloon valvuloplasty for relief of pulmonary valve obstruction even with angiographic features of pulmonary valve dysplasia. Also, it seems reasonable to use larger balloons than is recommended for nondysplastic pulmonary valves; we personally tend to use balloons large enough to produce balloon/ annulus ratios of 1.4 to 1.5 and tend to avoid ratios in excess of 1.5 for fear of damage to the right ventricular outflow tract.59 Injimdibular obstruction. Several reports identify infundibular obstruction as a complicating feature immediately following balloon valvu~~p~~~ty~2,3,7,49,52,55,58.70-72.98,103,1~,113,124,125
This
prob-
lem was further studied in order to define the prevalence and significance of infundibular obstruction in patients undergoing balloon valvuloplasty for valvar pulmonic stenosis;16 we used the data of 62 children who had undergone balloon angioplasty during a 55-month period ending May 1988. Thirteen of the 62 (21%) children had infundibular pressure gradients before valvuloplasty; these ranged between 10 to 137 mm Hg (49 -+ 42 mm Hg). Following valvuloplasty, infundibular gradients disappeared in 5 patients (Fig 17). The infundibular gradient in the remaining 8 patients were 33 & 26 mm Hg with a range of 5 to 80 mm Hg. In six of these eight patients, the infundibular gradients diminished when compared with prevalvuloplasty gradients. In one child, the gradient remained unchanged at 20 mm Hg, and in the final patient, the infundibular gradient increased from 40 to 45 mm Hg. In five additional patients without infundibular gradients but with angiographic infundibular narrowing, an infundibular gradient appeared after valvuloplasty; new infundib-
100 m =
SO
E _ 60 E $
40
E a
20
RAO
-
-
0 I
Before
Immediately After
Follow-up
Fig 17. Sequential infundibular gradients before and immediately after balloon pulmonary valvuloplasty and at follow-up are shown. Thirteen children had initial gradients, 5 disappeared following valvuloplasty. New gradients appeared in 5 other patients. The gradients either disappeared or improved at follow-up. (Reprinted with permission.16)
ular gradients were 15,30,34,50, and 69 mm Hg (40 & 21 mm Hg) (Fig 17). Thus, 18 of 62 (29%) patients had infundibular gradients before or immediately after valvuloplasty. Examples of severe infundibular reaction demonstrated by Doppler echocardiography and cineangiography are shown in Figs 18 and 19. One child received propranolol before valvuloplasty.18 Two other children, with what was thought to be successful balloon valvuloplasty, developed systemic-level pressures in the right ventricle because of severe infundibular reaction. Propranolol, 0.1 mg/kg, was slowly administered intravenously with decrease in the right ventricular pressures and infundibular gradients. These three and three other patients with infundibular stenosis were prescribed oral propranolol, 2 to 3 mg/kg/d in three to four divided doses, for approximately 3 months. None of the Madison group required surgical infundibular resection. Out of the total of 13 patients with infundibular gradients at the end of balloon valvuloplasty, the gradients disappeared at follow-up in 7 patients. No follow-up data was available in one child. In the remaining five patients with persistent infundibular gradients at follow-up, the gradients were low, range 10 to 47 mm Hg (mean, 29 mm Hg); in each patient, the gradient at follow-up was lower when compared with the immediate postvalvuloplasty gradient (Fig 17). The influence of severity of pulmonary valve obstruction and age of the patient on the development of infundibular obstruction was
Fig 18. following immediately follow-up, sion.7B)
Doppler flow velocity recordings from the main pulmonary artery before (left), and 1 day (center) and 10 months (right) balloon pulmonary valvuloplasty are shown. Note that there is no significant decrease in the peak flow velocity after valvuloplasty, but there is a characteristic triangular pattern, indicative of infundibular obstruction. At lo-month the flow velocity markedly diminished, suggestive of resolution of infundibular obstruction. (Reprinted with permis-
examined. The patients with infundibular obstruction (n = 18) had higher (P < .Ol) pulmonary valve gradients (119 2 51 mm Hg) than those (n = 44) without infundibular gradients (83 + 35 mm Hg). When the prevalence of infundibular obstruction was scrutinized (Table 7) patients with higher degrees of obstruction had a greater prevalence of infundibular stenosis. The age distribution of patients with and without infundibular gradients (9.8 + 7.1 v 8.2 ? 6.4 years) was similar (P > .l). However, the prevalence of an infundibular gradient was higher (P < .Ol) in older patients than in younger patients (Table 7). Several authors reported either persistence of right ventricular infundibular gradients or appearance of such gradients following balloon pu~monaryva~vu~op~asty~2.7.49.52,55,58.70.76.98,103,106.
113.
124~125 When such infundibular obstruction was severe, propranolol was administered by several groups of workers7~49,70.103J24 with variable re-
sults. Infundibular resection by surgery was required in three patients.70J’3JZs In a few studies with follow-up catheterization, the infundibular obstruction improved.7,49Js,58,9~~1Z4 The absence of a pressure gradient across an angiographically narrow right ventricular infundibulum in the presence of a more severe distal obstruction (valve stenosis) is well known126-128;this atypical behavior of multiple obstructions may be due to “forced vibration” with greater energy transfer into the cardiovascular segment upstream to the proximal obstruction than into the segment upstream to the distal obstruction.127J28 The elastic and pulsatile characteristics of the cardiovascular system are important for expressing this property.117,‘2x Once the valvar (distal) gradient was relieved, the infundibular (proximal) gradient appeared. Infundibular gradients immediately following valvuloplasty appear to be related to infundibular hyperreactivity and if severe (producing near
P. SYAMASUNDAR
134
Table
7. Relationship Between Severity Stenosis and Age With the Prevalence
of Pulmonary of lnfundibular
Valvar
Gradients No. of Patients in the Specified Group Pulmonary valve gradient 2 100 mm Hg
No. With lnfundibulat Gradients
21
9
Pulmonaryvalve gradient < 100 mm Hg
41
9
Pulmonary valve gradient 2 80 mm Hg
32
12
Pulmonary valve gradient < 80 mm Hg
30
Age Age
40 22
6 14
2 5 Years < 5 Years
*Chi-square Reprinted
with
4
P
VsllJe
< .Ol
< .Ol
< .Ol
permission.16
systemic pressure in the right ventricle), may need treatment with propranolol. We, indeed, observed significant improvement in the gradient following intravenous propranolol. This response is similar to that observed in patients with surgical pulmonary valvotomy.‘29 Although all Madison patients were managed without surgical resection of the infundibular obstruction, an occasional patient may require infundibular resection.70J13 Oral propranolol therapy may be required in some patients with significant infundibular obstruction; patients with an infundibular gradient in excess of 50 mm Hg, as suggested by Fontes et al,124 may be candidates for such therapy. The infundibular obstruction is expected to regress with time as has been observed following surgical pulmonary valvotvalvuloplasty.3.7,l",~s.Y~.1~4 OmY130-134 and balloon Whether propranolol has any effect in enhancing regression of infundibular obstruction cannot be answered by this study. Al Kasab and associatesio3 observed that five patients receiving propranolol before balloon dilatation developed insignificant infundibular gradients (12 + 4 mm Hg) following valvuloplasty, whereas six other patients not receiving propranolol developed more severe infundibular gradients (45 2 27 mm Hg). The latter gradient diminished (9 + 4 mm Hg) following propranolol. Although these authors did not recommend routine use of propranolol therapy before valvuloplasty, they implied the potential use of P-blockade. At this time, there is no
RAO
evidence to advocate routine use of p-blocking agents before valvuloplasty. Based on the Madison experience and that reported in the literature, the following considerations might help in the management of infundibular obstruction in patients with pulmanic stenosis following balloon valvuloplasty.‘” 1. Consider the possibility of development of infundibular obstruction after valvuloplasty in all patients with severe valvar pulmonic stenosis. 2. Perform careful pressure pullback recordings across the pulmonic valve and right ventricular outflow tract both before and 15 minutes following balloon pulmonary valvuloplasty. 3. Right ventricular cineangiograms should be performed and scrutinized for infundibular obstruction both before and 15 minutes following valvuloplasty. 4. Use adequate-sized balloon(s) so as to have a balloon/annulus ratio of 1.2 to 1.4 so that adequate relief of valvar obstruction occurs, which in turn, encourages resolution of infundibular obstruction. 5. Balloons that produce balloon/annulus ratios in excess of 1.5 should be avoided for fear of damage to right ventricular outflow tract muscle and precipitating the infundibular reaction. 6. If angiographic and pressure data suggest significant residual infundibular obstruction, P-blocking drug therapy may be necessary; it may be given if the residual gradient is in excess of 50 mm Hg. 7. If follow-up echo-Doppler or catheterization and angiographic studies performed 6 months to 1 year after balloon valvuloplasty show residual infundibular gradients 2 50 mm Hg, then consideration for surgical resection of the infundibular muscle should be given. If there is significant residual valvar obstruction, repeat balloon valvuloplasty with an adequatesized balloon(s) would be our therapeutic choice. With this approach, surgical resection of infundibular obstruction can be avoided in most, if not all, cases. In summary, infundibular gradients in association with balloon pulmonary valvuloplasty were documented in 29% (18 of 62) of patients. The prevalence of such gradients appears to be more frequent with increasing age and severity of valve stenosis. Some of these children may
CATHETER
THERAPY
OF PULMONARY
135
STENOSIS
develop systemic or suprasystemic pressures in the right ventricle because of hyperreactivity of the right ventricular infundibulum and may need P-blockade. The infundibular stenosis does regress to a great degree at follow-up. The potential for development of an infundibular gradient after balloon valvuloplasty should not deter physicians from the use of this technique for the treatment of valvar pulmonic stenosis. Conclusions Balloon pulmonary valvuloplasty has been used successfully over the last decade for the relief of moderate to severe valvar pulmonic stenosis in neonates, infants, children, and adults. Both immediate and intermediate-term follow-up results have been well documented by cardiac catheterization and Doppler studies. The results of balloon valvuloplasty are either comparable to or better than those reported with surgical valvuloplasty. Complications of the procedure have been minimal. The causes of restenosis have been identified, and appropriate modifications in the technique, particularly use of ballooniannulus ratio of 1.2 to 1.4, should produce better results than previously documented. Additional refinement of the catheters and technique may further reduce the complication rate and prevalence of restenosis. The indications for balloon valvuloplasty have not been clearly defined but should probably be similar to those used for surgical valvotomy; only patients with moderate to severe valvar pulmonic stenosis are candidates for balloon valvuloplasty. Previous surgery, pulmonary valve dysplasia, and Noonan syndrome are not contraindications for balloon valvuloplasty. lnfundibular reaction may be present in older patients and in patients with severe obstruction and can most often be managed with adequate valvuloplasty and p-blocking drugs with rare need for surgery. Miniaturization of the balloon/catheter systems, further refinement of the procedure, and meticulous attention to details of the technique may further reduce the complication rate and increase safety. Documentation of the favorable results at 5- to IO-year follow-up is necessary. Transcatheter techniques are excellent alterna-
tives to open or closed heart surgery in most, if not all, patients with pulmonary stenosis. SUPRAVALVAR
PULMONIC
STENOSIS
Stenosis of the main pulmonary artery may occur as an isolated anomaly or may be a component of other right ventricular outflow obstructive lesions such as valvar pulmonic stenosis and tetralogy of Fallot. It may also occur secondary to rubella syndrome. Supravalvar pulmonic stenosis may also develop at the site of anastomosis in the neopulmonary artery following an arterial switch procedure for transposition of the great arteries or it may be a residua after removal of a previous pulmonary artery band. There is only a limited experience with balloon dilatation of supravalvar pulmonary artery stenotic lesions.21,‘3.5-‘38 The indications for balloon angioplasty of these lesions should probably be similar to those recommended for valvar pulmonic stenosis”; moderate to severe peak-to-peak systolic pressure gradient (2 50 mm Hg) across the narrowed area in the face of normal cardiac index. Although there are no definitive guidelines, the size of the balloon should be at least two times the diameter of the narrowest site of obstruction. To the best of my knowledge, there is a single report of dilatation of native supravalvar pulmonary artery stenosis138 other than that used for cyanotic heart defects, discussed later in this review. Romero and his colleaguesl?” balloondilated discrete, “native” supravalvar pulmonary stenosis in seven children; they reduced peak systolic pressure gradients from 85 t 43 mm Hg to 27 5 17 mm Hg, P < .Ol. Follow-up studies at a mean of 3 years showed a residual gradient of 28 +- 12 mm Hg. They concluded that the discrete membranous or fibrous supravalvar obstructions can be effectively treated by balloon dilatation. We have attempted balloon dilatation in three children, ages 4, 6, and 19 years and reduced the gradients across the supravalvar stenosis; in two there were excellent results, but in the third, the gradient reduction was minimal. Two of these children manifested supravalvar pulmonary stenosis 4 and 15 years following surgical pulmonary valvotomy, respectively, and it is not clear whether the supravalvar stenosis
136
was native or developed secondary to surgery. The third child exhibited pulmonary artery narrowing 1 year following an arterial switch procedure for transposition of the great arteries. There was angiographic (Fig 20) and pressure gradient (Fig 21) relief in this child.*’ No follow-up data are available in these children. Schranz et al135 successfully balloon-dilated supravalvar pulmonary stenosis in a single patient who developed it following an arterial switch procedure. Zeevi and associates’36 attempted balloon angioplasty of postarterial switch supravalvar stenosis in five children and produced 1% to 75% gradient reduction; their assessment was that only one patient had a successful result with reduction of the peak-topeak systolic pressure gradient from 79 mm Hg to 20 mm Hg. Of the four patients with poor results, three underwent surgical relief 0 to 6 months after angioplasty. Saxena et a1i3’ attempted eight balloon dilatations in five chil-
P. SYAMASUNDAR
RAO
dren who developed supravalvar pulmonary stenosis following arterial switch procedures for transposition of the great arteries. In none of these dilatations was there any improvement in the pressure gradient across the area of obstruction nor was there any significant angiographic change. 13’ Based on the limited experience thus far documented,“J35-i37 it appears that discrete narrowing at the suture lines in the neopulmonary artery is likely to be relieved by balloon dilatation, whereas diffuse narrowings secondary to anteroposterior flattening13h or shrinkage and retraction of the pericardial patch’“’ used in the enlargement of neopulmonary artery are unlikely to respond to balloon angioplasty. Balloon dilatation was attempted in two patients with residual supravalvar pulmonary stenosis following removal of a previously placed pulmonary artery band.‘j6 The peak-to-peak pressure gradients were reduced from 60 and 65 mm Hg to 38 and 35 mm Hg, respectively. The percent reduction of the gradient was 37 and 42, respectively, and the data were interpreted as partially successful balloon dilatation.‘3h In summary, supravalvar pulmonary stenosis that develops following previous surgery can be relieved by balloon dilatation if it is a discrete narrowing. Balloon angioplasty should probably not be attempted if the obstruction is diffuse.4” There are limited data for native supravalvar pulmonic stenosis. PULMONARY STENOSIS WITH ATRIAL RIGHT-TO-LEFT SHUNT
This group of patients has very severe pulmonary stenosis with a resultant increase in right ventricular and atria1 pressures with consequent right-to-left shunting either across a patent foramen ovale or an atria1 septal defect.
Fig 20. Cine frames from lateral views of pulmonary artery cineangiograms showing supravalvar pulmonary stenosis (arrow) following arterial switch procedure (A) which improved markedly following angioplasty (B). (Reprinted with permission.zl)
Indications Any patient with severe enough pulmonary valve obstruction to produce right-to-left atria1 shunting and arterial desaturation is a candidate for relief of the pulmonary valve stenosis. No age or weight (size) are contraindications. It is important to relieve the pulmonary valve obstruction before deterioration of right ventricular function develops. The technique of balloon dilatation is described in Appendix 2.
CATHETER
THERAPY
OF PULMON
IARY
STENOSIS
137
Fig 21. Pressure pullback tracings across the supravalvar pulmonary stenosis showing significant pressure gradient (A) which diminished markedly following balloon angioplasty (6). Aortic pressure is also shown in 6. Ao, aorta; DPA, distal pulmonary artery; PPA, proximal pulmonary artery. (Reprinted with permission.zl)
Results Immediate results. Although some of the investigators, as listed elsewhere,46 may have mentioned patients with right-to-left shunt, none have grouped the patients in a manner similar to the grouping in this review. From our study group, we had 12 patients, aged 3 days to 11.5 years (median, 8 months), who underwent balloon pulmonary valvuloplasty.20 All had severe valvar pulmonic stenosis with intact ventricular septum and interatrial right-to-left shunting. The right ventricle was hypoplastic in 3 infants; severe infundibular stenosis was present either before or immediately after balloon angioplasty in 5 children, in a manner described elsewhere’$ poor right ventricular function was evident in 2 children; and Ebstein’s anomaly of the tricuspid valve was present in 1 infant. The right ventricular peak systolic pressure was above that in the left ventricle in 9 children and pressures were similar in both ventricles in the remaining 3. There
was a varying level of hypoxemia with a mean arterial oxygen saturation of 83 2 8% (mean 2 SD) with a range of 64% to 91%. The arterial desaturation is secondary to interatrial right-toleft shunting in all cases. Following balloon pulmonary valvuloplasty, the arterial oxygen saturation increased from 83 ? 8% to 94 2 5% (P < 0.001); in only 1 child was the oxygen saturation less than 91% after valvuloplasty. The pulmonary blood flow index (1.9 + 0.5 L/min/m2 v 2.8 ? 0.6 L/min/m2, P < .OOl), pulmonary-to-systemic flow ratio (Qp: Qs)(0.7 f. 0.1~1.0 + 0.2,P < .OOl),andpulmonary artery pressure (15 + 6 mm Hg v 27 & 9 mm Hg, P < .Ol) increased after valvuloplasty. Peak systolic pressure gradients across the pulmonary valve decreased (P < .OOl) from 105 & 48 mm Hg to 25 + 18 mm Hg. Infundibular pressure gradients were recorded before valvuloplasty in 2 children; these were 20 and 130 mm Hg. These gradients changed, respectively, to 27 and 30 mm Hg after balloon valvuloplasty.
P. SYAMASUNDAR
138
lnfundibular gradients that were not present before valvuloplasty appeared in 2 children; these were 30 and 11.5mm Hg. Right ventricular cineangiography showed a greater movement of the leaflets of the pulmonary valve and a wider jet of contrast material passing across the pulmonary valve when compared with prevalvuioplasty cineangiograms. A hyperactive infundibular region was observed before and/or after valvuloplasty in 5 children, including the 4 in whom pressure gradients were recorded. The size of the right ventricle increased dramatically in a 7-day-old infant with critical pulmonary stenosis and hypoplastic right ventricle.h The size of the right ventricle decreased markedly in one child with associated Ebstein’s anomaly of the tricuspid valve. All but the two neonates were discharged home on the morning following balloon pulmonary valvuloplasty. The 2 neonates (3 and 7 days old), who were on ventilators at the time of valvuloplasty, were discharged home within 1 week after valvuloplasty. No complications other than an episode of supraventricular tachycardia in 1 neonate (which resolved spontaneously) were encountered. Follow-up results. Clinical and echo-Doppler follow-up data are available in 11 children, 1 to 31 months (mean, 12 months) following balloon dilatation, and cardiac catheterization was performed in 7 children, 6 to 18 months (11 2 4 months) after valvuloplasty. Arterial oxygen saturation (94 ? 6%) pulmonary blood flow (3.5 ? 0.9 L/minlm2), and Qp:Qs (1.0 -+ 0.1) remain improved (P < .Ol to .OOl) when compared with prevalvuloplasty values, but essentially unchanged (P > .l) when compared with immediate postvalvuloplasty values (Table 8). The pulmonary valvar gradient (33 & 33 mm Hg) continues to be lower (P < .OOl) than that Table
8. Results
of Balloon
Pulmonary
PA pressure, Pulmonary Hemoglobin, PA Doppler
mm Hg valve gradient, 9% flow velocities,
83 k 8
Right-to-Left P
Value’
Shunt
Group
1 to 31 Months After BPV (N = 10)
Value’ -. .Ol
P
94 t 5
i ,001
94 t 6
*. ,001
1.0 k 0.1
. .OOl
1.9 f 0.5
2.8 t
0.6
*: ,001
3.5 k 0.9
'. .OOl
15 k 6
27 t
9
‘. .Ol
17i
6
L ,001
33 i
33
105 15.4
m/s
Both the immediate and intermediate-term follow-up results are good with relief of right ventricular hypertension and systemic arterial hypoxemia. The group with intact ventricular septum and interatrial right-to-left shunting behaved in a manner similar to that observed with isolated pulmonary valve stenosis.“,7,‘T Despite restenosis of the pulmonary valve in two children, requiring repeat balloon dilatation, overall results are gratifying. Persistent hypoxemia was observed in only one child with a hypoplastic right ventricle and severe residual
1.0 + 0.16
0.7
mm Hg
Comments
Immediately After EIPV (N = 12)
(N = 12)
Arterial O2 sat, % Qp:Qs OP. L/minlmz
before valvuloplasty, but unchanged (P > .I) when compared with the immediate postvalvuloplasty gradient. Infundibular gradients disappeared in 2 children, decreased further in 1 child, and a significant residual (50 mm Hg) was present in the remaining child. Despite improvement as a group, 2 children had significant residual pulmonary valvar gradients, and repeat balloon pulmonary valvuloplasty was performed at the follow-up catheterization with reduction of gradients from 94 and 61 mm Hg to 26 and 18 mm Hg, respectively. None required surgical intervention and 2 children remain on B-blocking agents. Doppler studies (performed in a manner similar to that described elsewher+‘) at the last follow-up examination showed a mean Doppler flow velocity of 2.6 + 0.7 m/s across the pulmonary valve, which had been 4.9 ? 0.9 m/s before valvuloplasty (Table 8).“” Calculated instantaneous pressure gradients (26 rfr 10 mm Hg) were lower (P < .OOl) than those before valvuloplasty (100 t 36 mm Hg). No complications were observed at the follow-up catheter and clinical evaluation.
Valvuloplasty-Atrial
Before BPV
RAO
r 0.1
+48
25518
5 2.8
12.1
4.9 + 0.9
Abbreviations: BPV, balloon pulmonary valvuloplasty; Qp:Qs, pulmonary-to-systemic blood flow ratio. *Compares with values obtained before BPV. Reprinted with permission of Wiley-Liss, a division
2.7 2 0.8
O2 sat, oxygen
of John
Wiley&Sons,
< ,001
saturation;
Inc.20
PA, pulmonary
t
1.4
2.6 2 0.7
artery;
Qp, pulmonary
..l .OOl
. .Ol x .OOl
blood
flow;
CATHETER
THERAPY
OF PULMONARY
STENOSIS
infundibular obstruction. This child might need surgical resection of infundibular obstruction at a later date. Infundibular obstruction resolved in the remaining patients in a manner described by UP and others.71 Conclusion
Balloon pulmonary valvuloplasty appears to offer excellent relief of pulmonary oligemia, systemic arterial hypoxemia, and right ventricular hypertension in patients with pulmonary stenosis with intact ventricular septum and right-to-left atria1 shunting. Based on the data presented, it is suggested that balloon valvuloplasty is the procedure of choice for treatment of this group of patients. PULMONARY
STENOSIS WITH VENTRICULAR RIGHT-TO-LEFT SHUNT
The group of patients considered under this section are those that have severe pulmonary stenosis in association with a (usually) large interventricular communication. The most common type of defect in this category is tetralogy of Fallot (TOF). Other defects include transposition of the great arteries, double-outlet right (or left) ventricle, and ventricular inversion (corrected transposition of the great arteries), all with a large ventricular septal defect and severe pulmonic stenosis. Other defects, such as single ventricle and tricuspid atresia, fall into this category, provided pulmonary stenosis is present. Indications
The indications for balloon pulmonary valvuloplasty that we have used6,20 were cardiac
Fig 22. Selected cineangiographic frames from patients with tetralogy of Fallot (A) and d-transposition of the great arteries (B), demonstrating two sites of pulmonary outflow obstruction (two arrows). When the pulmonary valve obstruction is relieved by balloon valvuloplasty, the subvalvar obstruction remains and prevents flooding of lungs. Ao, aorta; LV, left ventricle; PA, pulmonary artery; RV, right ventricle. Reprinted with permission of Wiley-Liss, a division of John Wiley & Sons, Inc.za
139
defects not amenable to surgical correction for the age and size of the patient at the time of presentation, but, at the same time, requiring palliation for pulmonary oligemia. Symptoms related to hypoxemia and polycythemia are indications for intervention. Hypoplasia of the pulmonary valve ring, main and/or branch pulmonary arteries, is another indication even if symptoms are not present. The presence of two or more sites of obstruction to pulmonary blood flow (Fig 22) was considered a prerequisite when using balloon valvuloplasty, because if valvar stenosis is the sole obstruction, relief of such an obstruction may result in a marked increase in pulmonary blood flow and elevation of pulmonary artery pressure and resistance. The technique of balloon valvuloplasty for this group of children is described in Appendix 3. Results Immediate results. Balloon pulmonary valvuloplasty for infants with cyanotic congenital heart defects with pulmonary oligemia was used by uGZfl and others69s’40-i43to augment pulmonary blood flow. McCredie and associates@’ used balloon dilatation of the stenotic pulmonary valves in two patients, one with TOF and the other with tricuspid atresia, and reported improvement in exercise tolerance in both and improvement in oxygen saturation from 83% to 89% in one child. Boucek et alI4 were successful in performing balloon pulmonary valvuloplasty in seven of the eight patients in whom they attempted the procedure. The diagnoses in these seven patients were TOF in five; transpo-
P. SYAMASUNDAR
140
three; and dextrocardia, ventricular inversion with ventricular septal defect, and valvar and subvalvar pulmonary stenosis in the final case. Following balloon pulmonary valvuloplasty, the arterial oxygen saturation increased from 67 & 13% to 83 + 13% (P < .Ol). The pulmonary blood flow index (2.1 t 0.8 L/min/m? v 3.2 ? 1.2 L/min/m2, P < .05), Qp:Qs (0.7 + 0.4 1’ 1.2 + 0.5, P < .02), and pulmonary artery pressure (16 + 5 mm Hg v 21 ? 11 mm Hg, P < .02) increased following balloon dilatation (Table 9). The pulmonary valvar gradients (52 ~fr16 mm Hg v 32 2 22 mm Hg) decreased (P < .05), whereas infundibular gradients (33 f 12 mm Hg v 42 & 16 mm Hg) and total pulmonary ventricular outflow tract (valvar plus subvalvar) gradients (77 ? 14 v 66 ? 12 mm Hg) remained unchanged (P > . 1) after valvuloplasty. An example is shown in Fig 23. None required immediate surgical intervention. No complications were encountered during the procedure. All children were discharged home within 24 hours of the procedure. Follow-up results. There are limited follow-up data. Boucek et alr40 reported 0.5 to 2.8-year follow-up results; four TOF patients underwent surgical correction, one patient underwent systemic-to-pulmonary artery anastomosis, and the other two did not require surgical correction. Qureshi and associates14’ reported follow-up observations after balloon angioplasty of 15 TOF patients. Seven children did not require further palliation during a mean follow-up period of 12.9 months (3.5 to 26 months). Four children required systemic-to-
sition of the great arteries, ventricular septal defect, and pulmonic stenosis in one; and ventricular inversion, ventricular septal defect, and pulmonic stenosis in the final patient. The systemic arterial oxygen saturations increased from 72 + 5% to 83 2 5% (P < .005). The pulmonary blood flow and pulmonary arterial pressure also increased. Qureshi et al141 reported their observations after balloon dilatation of the pulmonary valve in 15 patients with TOP, the systemic arterial oxygen saturation increased in the majority of patients. In four of these children, either no significant change or a deterioration in oxygen saturation occurred, and they received systemic-to-pulmonary artery shunts 1.6 months (0 to 3 months) after the procedure. Six children did not require further intervention. They concluded that balloon dilatation may be useful in the management of infants with severe TOF, and that it should be considered for the initial palliative treatment.141 Mehta and Perlman142 reported a single patient with TOF in whom balloon pulmonary valvuloplasty increased oxygen saturation from 80% to 90%. The Madison experience with this procedure, including that previously reported,6~2(i,” was in 11 infants with cyanotic congenital heart defects, aged 3 months to 3 years (median, 10 months), weighing 5.4 to 16 kg (median, 8.0 kg), who underwent balloon pulmonary valvuloplasty as a palliative procedure to improve pulmonary oligemia. The diagnoses in these cases were TOF in 7 children; transposition of the great arteries, with ventricular septal defect and valvar and subvalvar pulmonary stenosis in Table
Arterial
9. Results
of Balloon
Pulmonary
0, sat, %
Qp:Qs Qp, L/min/m2 PA pressure, mm Hg Pulmonary valve gradient, mm Hg lnfundibular gradient, mm Hg Total gradient across, PV outflow, mm Hg Hemoglobin,
9%
Abbreviations: Qp, pulmonary *Compares tP > 0.1. Reprinted
SPV, balloon pulmonary blood flow; PA, pulmonary with with
value permission
obtained
before
of Wiley-Liss.
Valvuloplasty-Ventricular
Right-to-Left
Shunt
Group
4 to 36 Months After BPV (N = 11)
P Value’
Before BPV (N = 11)
Immediately after BPV (N = 11)
P Value*
67 + 13 0.7 + 0.4
83 + 13 1.2 t- 0.5
.l > .05
0.8 5 16 12
77 + 14 16.5 + 2.9
-
valvuloplasty; O2 sat, oxygen artery; PV. pulmonary ventricle,
saturation;
EPV. a division
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of John
Wiley
81 Sons,
lnc.*0
Op:Qs,
1.7 6 7 18t 13
> .l
15.8 + 2.7
> .1
pulmonary-to-systemic
rt k 2 I?
> .05 c ,001
c .02
blood,
flow
ratio;
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141
Fig 23. Pressure pullback tracings across the pulmonic valve and right ventricular outflow tract before (A), 15 minutes (6) and 12 months (C) after balloon pulmonary valvuloplasty in a patient with tetralogy of Fallot. Note both valvar and infundibular gradients were present before valvuloplasty (A), whereas the valvar gradient almost completely disappeared and infundibular gradient persisted immediately after (B) and 12 months (C) following valvuloplasty. MPA, main pulmonary artery; RVB, right ventricular body; RVO, right ventricular outflow tract. (Reprinted with permission of WileyLiss, a division of John Wiley & Sons, Inc.20)
pulmonary artery shunt operations 0 to 3 months (mean, 1.6 months) after angioplasty. The final four patients had a corrective operation 6 to 16 months (mean, 8 months) after balloon dilatation. From the Madison group,20 all 11 children have been followed for 6 to 36 months (13 k 10 months) with pulse oximetry and hemoglobin determinations. Cardiac catheterization was also performed in all 11 children 4 to 12 months (median, 11 months) following valvuloplasty. Arterial oxygen saturation (82 + 9%), pulmonary blood flow (4.0 +- 1.7 L/min/m*), and
Qp:Qs (1.3 k 0.7) remain unchanged (P > .l) from the immediate postvalvuloplasty values, but remain improved (P < .05 to “001) when compared with prevalvuloplasty values (Table 9). The hemoglobin level (15.8 2 2.7 g %) did not change (P > .l) when compared with the prevalvuloplasty value of 16.5 + 2.9 gm %. The pulmonary valve gradient (18 k 7 mm Hg) remains improved both when compared with that recorded before (P < .OOl) and immediately after (P < .0.5) valvuloplasty (Table 9). The subvalvar (53 + 18 mm Hg) and total pulmonary ventricular outflow tract (69 2 13 mm Hg)
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gradients remain unchanged (P > .l). An example is shown in Fig 23. None of the patients had significant elevation of peak systolic pulmonary artery pressure: 22 2 6 mm Hg; range 12 to 30 mm Hg. Four children with TOF underwent successful total surgical correction 4 to 24 months (12 + 9 months) following valvuloplasty. Two of these children had very small pulmonary arteries before valvuloplasty and were initially considered unsuitable for total surgical correction. Approximately 12 months later, the pulmonary artery anatomy improved (Fig 24) and total surgical correction was performed without incident. The other two children were operated on 4 and 5 months after balloon valvuloplasty because they developed cyanotic spells. The remaining 3 children with TOF are clinically doing well and await surgery. Two children in the transposition group showed evidence for significant hypoxemia on follow-up and Blalock-Taussig shunts were performed 6 and 18 months following initial balloon valvuloplasty. Increase in the size of the pulmonary artery, as previously reported,6 was observed. The remaining transposition patient and the single patient with corrected transposition (ventricular inversion) are clinically well and no further intervention is planned. Complications Complications have been remarkably minimal. A transient decrease in systemic arterial saturation occurs while the balloon is inflated but rapidly improves following balloon deflation. Surprisingly, cyanotic spells following balloon valvuloplasty have not been a problem,
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presumably because of improvement of pulmonary blood flow following the procedure. However, increasing cyanosis has been observed by some workers.14* Hypotension during balloon inflation, which is so common in balloon dilatation of pulmonic stenosis with intact ventricular septum,23 is usually not observed in this group of patients, presumably because the flow through the ventricular septal defect provides adequate systemic ffow. Pulmonary arterial tear’“” has been reported in a 3-year-old child, which was noted at the time of total surgical correction 15 months following valvuloplasty. Femoral venous occlusion may be observed at follow-up”.“’ but without adverse effects. Comments Lababidi and colleaguesh4,“’ were the first to report balloon valvuloplasty in patients with tetralogy of Fallot. However, they did not advocate the procedure for patients with TOF. While evaluating the mechanism of balloon pulmonary valvuloplasty,h4J23 they examined the role of balloon valvuloplasty in TOF and suggested that in the presence of combined infundibular and valvar pulmonic stenosis, balloon fixation by the infundibulum causes retraction of the balloon into the ventricle during systole, which may cause avulsion of the valve cusp. Therefore, they did not recommend balloonvalvuloplasty in these patients.“” Subsequently, several groups of workers, including our group, 6,20.21,69,140-143 reported successful balloon pulmonary valvuloplasty to improve pulmonary oligemia, which were just reviewed. The immediate results of balloon pulmonary valvuloplasty in this group of patients appear
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good and attained the objective of improving pulmonary oligemia and systemic arterial hypoxemia. Immediate surgical intervention was avoided in most cases. Intermediate-term results are also good, the augmentation of pulmonary blood flow continuing to be present at follow-up in most children. The size of the pulmonary arteries improved in most patients, making them more suitable for further palliative or total surgical corrective procedure. Battistessa et a1’45 reported their observations at surgery for TOF patients who had previously undergone balloon pulmonary valvuloplasty. Results in 27 patients (which included 15 patients previously reported by Qureshi141 and probably form a subgroup of their larger experience’“‘) were scrutinized. They found anatomic alterations in the right ventricular outflow tract in 20 (74%) patients, whereas no change was observed in 7 (26%). They also noted that there was no evidence for significant growth of the pulmonary valve annulus and that the need for a transannular patch was not abolished at the time of intracardiac repair. In view of the damage to the pulmonary valve mechanism and no evidence for enough growth of the pulmonary valve to obviate the need for transannular patch at a later corrective surgery, they were not very supportive of balloon valvuloplasty as a palliative procedure. Although these observations are important, we6.?0 and others1JnJJl.14hhave documented an increase in the size of the pulmonary artery and/or annulus following balloon pulmonary valvuloplasty. The increase in the pulmonary arteryiannulus size is demonstrated in a larger group of patients,13-i which included Battistessa’s patients.145 The increase (P < .OOl) in pulmonary valve annulus size was demonstrated in 24 patients who also increased their systemic arterial oxygen saturations following balloon valvuloplasty, and this increase in pulmonary annulus size was greater (P < .00.5) than expected from normal growth. This improvement in the size of the pulmonary arteriesh,"),l40.14~.14~ is similar to that observed following a Brock procedurei47J4x and systemicto-pulmonary arterial shunts.149-1s2 In view of the varied observations, it would seem prudent that balloon pulmonary valvuloplasty in TOF (or any other cyanotic defects) should be performed in only selected patients.
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The following criteria are proposed: (1) the infant/child requires palliation of pulmonary oligemia but is not a candidate for total surgical correction either because of the size of the patient, the type of the defect, or because of anatomic aberrations, (2) valvar obstruction is a significant component of the right ventricular outflow tract obstruction, (3) multiple obstructions in series (Fig 22) are present so that there is residual subvalvar obstruction after relief of pulmonary valvar obstruction and flooding of lungs is prevented. Once balloon valvuloplasty is decided on, balloons large enough to give a balloon/annulus ratio of 1.2 to 1.4 are recommended.6,‘,l?.‘0.“X New Developments Obstruction to the pulmonary outflow tract is usually at multiple levels in TOF; the sites of obstruction are pulmonary arteries, pulmonary valve leaflets, pulmonary valve ring, and infundibulum. Relief of valvar obstruction can, in some patients, increase forward flow and encourage growth of the pulmonary valve ring and pulmonary arteries, as discussed above. If severe infundibular stenosis is present, relief of pulmonary valve stenosis alone may not accomplish the objectives of relieving systemic hypoxemia and encouraging growth of the pulmonary arteries. Qureshi and associatesis’ used a Simpson coronary atherectomy catheter to perform infundibular myectomy in a 16mont h-old child with TOF. The systemic arterial saturation improved from 78% before the procedure to 85% a month later, and the right ventricular outflow tract became wider. They suggested that this type of transcatheter resection of the infundibulum may be important in the palliation of TOF. Further clinical trials of this method in selected patients are warranted to determine whether this method may serve as a useful adjunct to balloon pulmonary valvuloplasty in the management of TOF. Conclusion Balloon pulmonary valvuloplasty appears to offer excellent rehef of pulmonary oligemia and systemic arterial hypoxemia in patients with tetralogy of Fallot-type hemodynamics. Based on the data presented, it is recommended that balloon pulmonary valvuloplasty be used in the
144
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management of patients with cyanotic heart defects and pulmonary oligemia. It is an effective alternative to surgical creation of a systemicto-pulmonary arterial anastomosis, thus avoiding potential complications associated with surgical shunts.154-157The procedure is likely to be beneficial if the valvar obstruction is the dominant obstruction. The presence of two or more obstructions in a series is desirable to prevent flooding the lungs when the procedure proves successful. NARROWED
SYSTEMIC-TO-PULMONARY ARTERY SHUNTS
Cyanotic congenital heart defects with pulmonary oligemia secondary to severe pulmonary stenosis or pulmonary atresia usually require a systemic arterial-to-pulmonary arterial shunt operation to augment pulmonary blood flow and to improve arterial oxygen saturation. Narrowing of these shunts can occur postoperatively with resultant inadequate oxygenation. These narrowed shunts can be balloon dilated.22J58-162Gibbs and associatesls8 reported balloon dilatation of a narrowed Waterston (ascending aorta-to-right pulmonary artery) shunt in a 13-year-old child with pulmonary atresia and multiple shunts. The size of the stoma of the Waterston anastomosis was 3 mm. They initially used an &mm balloon catheter and did not observe “waisting” of the balloon and, therefore, repeated the procedure with a 12-mm balloon. There was a dramatic increase in arterial oxygen saturation (76% to 96%) and pulmonary artery pressure (15/ 11 mm Hg to 42130 mm Hg). However, the child died 12 hours later because of unilateral pulmonary edema. Autopsy findings were enlargement of the Waterston shunt to 10 mm and a congested and edematous right lung. The other shunts were completely occluded without any blood supply to the left lung. The complication in this child may have been caused by the use of a very large balloon to dilate the Waterston shunt. More data and experience with this lesion are necessary before making any definitive recommendation. The experience in dilating narrowed classical and modified Blalock-Taussig (BT) shunt 22~159-162 is more favorable and will be discussed in detail.
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Indications The indication for dilating narrowed BT shunts is the presence of cyanotic heart defects not amenable to total surgical correction at the time of presentation either because of age and size of the patient or because of anatomic complexity, while at the same time requiring palliation of pulmonary oligemia.2’ The majority of these patients have associated pulmonary atresia or have a pulmonary artery that cannot be catheterized directly, either because of the severity of obstruction or because of an abnormal or atypical position. Measurement of pulmonary arterial pressure and demonstration of pulmonary arterial anatomy are of obvious value in the overall patient management. This is an additional indication for balloon angioplasty of narrowed BT shunts. The technique of balloon angioplasty is described in Appendix 4. Results Acute results. Balloon angioplasty of a narrowed BT shunt was initially reported by Fischer et alls9 and subsequently by others.‘**h0-163Fischeris dilated a narrowed classical BT shunt in a 4-year-old child and increased systemic arterial saturation from 68% to 80%. Marx and associates160 successfully performed this procedure in five of six patients in whom they attempted the dilatation. Two of the five patients benefited markedly and one moderately. In the remaining two patients, no benefit could be shown. It is not clear whether these are classic or modified BT shunts that were dilated. Parsons and his colleagues161 balloon-dilated proximal stenosis of a modified right (GoreTex; Gore & Associates Inc, Elkton, MD) BT shunt in a 17-month-old child with tricuspid atresia and increased arterial oxygen saturation from 73% to 80%. There also was angiographic improvement. Rheuban and Carpenter,162 while discussing pediatric interventional procedures, presented angiograms of a patient that underwent balloon dilatation of a narrowed proximal anastomosis of what appears to be a modified (Gore-Tex) BT shunt. Significant angiographic improvement is noted, but no oxygen saturation data were provided. Marks and associates’“” balloon-dilated classic BT shunts in five chil-
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dren, aged 11 to 67 months, and increased their oxygen saturation from 73 + 9% to 84 f 3%. The Madison experience with this procedure, including that previously reported,22 is in eight children. There were four boys and four girls with a weight range of 6.2 to 19.6 kg (mean, 11.0 kg). The diagnoses in these children were pulmonary atresia in four (one with intact ventricular septum, two with large ventricular septal defects, and the final patient with mitral atresia, hypoplastic left ventricle, and double-outlet right ventricle), tricuspid atresia in three, and single ventricle, single atrium, and severe valvar and subvalvar pulmonic stenosis in the final patient. Each of these children underwent a BT shunt either in the neonatal period (five patients) or in early infancy (three patients). All children were cyanotic with increased hemoglobin values, 19.0 2 2.7 gm % (mean + SD), with a range of 14.8 to 22.1 gm %. Three children were severely symptomatic and were unable to attend school. Three toddlers were severely cyanotic with hyperpnea. The remaining two children were cyanotic and tolerated normal activity. There was moderate to severe hypoxemia with a mean oxygen saturation of 71% (SD * 7%), with a range of 62% to 82%. The pulmonary artery pressure was low normal in four children in whom the pulmonary artery pressure could be measured before angioplasty. In one child with long segmental narrowing of the left subclavian artery (in a patient with right aortic arch) proximal to its entry into the left pulmonary, there was no significant improvement in the oxygen saturation or in the angiographic appearance of the BT shunt. The angioplasty was considered to be a failure, and the child underwent a right BT shunt within several weeks after balloon angioplasty. In the remaining children, there was significant improvement. The arterial oxygen saturation increased from 71 + 7% to 81 & 4% following balloon angioplasty. Pulmonary artery pressures were measured in each case following angioplasty, and the peak systolic pressure was 14 f 5 mm Hg, with a range of 9 to 23 mm Hg; none had elevated pulmonary artery pressures. Angiographic improvement of the BT shunt with a greater degree of opacification of the pulmonary circuit was observed in each of the seven
145
children. Examples are shown in Figs 25, 26, and 27. No complications were encountered during the procedure. Follow-up results. Follow-up data after balloon angioplasty of narrowed BT shunts is scanty. Fischer159 commented that the dilated shunt was patent 2 months after angioplasty. Marxr60 stated that on short-term follow-up, three patients (of five) improved and two did not benefit. Parson’@ patient maintained clinical improvement for 4 months following angioplasty. At repeat catheterization, the arterial oxygen saturation was 76% (which was 73% before angioplasty and 80% immediately after angioplasty), and the dilated proximal anastomotic site was patent without restenosis or aneurysmal formation. MarkG3 followed five children for 6 -t 2 months after angioplasty, and their oxygen saturation by pulse oximetry remained improved at 82% to 90%. Two of these five patients were recatheterized 39 and 50 months after angioplasty, and the diameter of the dilated shunt, oxygen saturation, and pulmonary artery pressure remained unchanged at follow-up when compared with immediate postangioplasty values. From the Madison series, the single child with failed balloon angioplasty (of left BT shunt) underwent successful right BT shunt and demonstrated improved arterial oxygen saturation. The remaining seven children were followed for 3 to 24 months (mean, 12 months). The children with symptoms of exercise intolerance improved markedly, although all of them remained cyanotic. Hemoglobin levels decreased from 19.0 f 2.7 gm % to 17.1 2 1.9 gm %. Arterial oxygen saturation by pulse oximeter remains improved as a group (78 -+ 10%). Auscultation showed a continuous murmur of the shunt in five patients, but on echo-Doppler study, the shunt was patent in six children. Repeat catheterization was undertaken in two children because of progressive hypoxemia. The O2 saturations decreased. Although the shunts were patent, because of continued hypoxemia, BT shunts were successfully performed on the contralateral side 8 and 10 months after the balloon angioplasty. The remaining children were doing well clinically with continued palliation of pulmonary oligemia.
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Complications No complications were detected either in the Madison series or the patients reported by other workers.r59-163 It is somewhat surprising that there was no significant hypoxemia during balloon inflation (and consequent complete oc-
Fig 26. Right innominate artery (RI) cineangiographicframes before (A) and immediately following (B) balloon angioplasty. Note slight, but significant, improvement in the narrowed segment of the right subclavian artery (RSC) and the anastomotic site (arrow). LPA, left pulmonary artery; RCC, right common carotid artery; RPA, right pulmonary artery.
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elusion of BT shunt); presumably, this is because of alternative sources of pulmonary blood supply either through bronchial collateral vessels, a contralateral BT shunt, or through the stenotic pulmonary valve.” Because of reported instances of acute block-
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Fig 27. Aortic arch cineangiographic frames with the catheter tip positioned very close to the left innominate artery. Note the two areas of narrowing (arrows) in the left subclavian artery before balloon angioplasty (A), which have completely disappeared after angioplasty [B). Cl, arterial catheter in the aorta (right aortic arch); C2, venous catheter in superior vena cava; LCC, left common carotid artery; RPA, right pulmonary artery.
age of the BT shunts following catheter manipulation,1@J65 such complications can occur following balloon angioplasty. Close monitoring to ensue patency of the BT shunt in the postdilatation period is highly recommended. If such blockage occurs, consideration should be given to administration of intravenous streptokinase165or similar thrombolytic agents. Comments The immediate results of balloon angioplasty of narrowed BT shunts are good, and they accomplish the objective of improving pulmonary blood flow and hypoxemia in most patients. It appears that balloon angioplasty can be performed in both classical and modified (GoreTex) BT shunts. These results are similar to those following balloon pulmonary valvuloplasty for cyanotic congenital heart defects.6.2(1.69.140-‘43 During the short follow-up period, more than 50% of patients maintain symptomatic relief, whereas the others required additional palliation or correction. There are other benefits: in two children from the Madison study group with either complete or almost complete blockage of the BT shunt no catheter could be advanced into the BT shunt, but a balloon-on-a-wire could be advanced, with which the shunt was dilated, followed by the introduction of a catheter. This has resulted in obtaining pulmonary artery pressures directly and in good quality pulmonary arteriograms (Fig 28) information of obvious value in patient management, in addition to improving the arterial oxygen saturation.
Although there are many different ways of catheterizing the BT shunt and dilating it, the method that was used in the Madison series, namely (1) positioning an end-hole type of catheter in the vicinity of subclavian artery, passing a flexible (0.014 in) guidewire into the BT shunt and pulmonary artery and dilating with low-profile coronary-dilating catheters, and (2) failing the above, passing a balloon-on-awire to initially dilate the shunt and then redilate with a coronary-dilating catheter has been successful. OtherPO have used Cook Cobra and Headhunter catheters (Cook, Inc., Bloomington, IN) with success. It is not clear as to what is the most appropriate-sized balloon that should be used for balloon angioplasty; it should probably be 2.5 to 3.0 times the narrowest site. In general, balloons as large as the size of the subclavian artery feeding the shunt should be used, and such large balloons may be necessary to achieve adequate dilatation.22 As pointed out by Marx,iho use of small balloons may not produce adequate improvement in oxygen saturation and may have been the reason for only modest success of this procedure in his patients.i60 When there is difficulty in advancing a large balloon-dilating catheter, use of an extra-stiff guidewire (for example, extra-stiff Amplatz Cook guidewire [Cook, Inc.]) is helpful and recommended. Use of heparin (100 U/kg) during the procedure is recommended to prevent thrombosis. We continue heparinization for 24 hours following the procedure to prevent acute blockage165 following angioplasty. We do not use platelet-
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Technique of catheterization of Blalock-Taussig shunt when it is completely or almost completely occluded. A right Fig 28. innominate (RI) artery cineangiographic frame showing right common carotid (WC) artery and right subclavian (WC) artery; the latter is completely blocked. Having not been able to catheterize it in the usual manner, a 2-mm balloon-on-a-wire was advanced into the shunt and the balloon was inflated (B). Subsequently, a 5-F multi-A2 catheter was introduced into the pulmonary artery and a cineangiogram (C)was performed. Note the main (MPA), right (RPA), and left (LPA) pulmonary arteries; the LPA was not completely opacified because of flow from the left Blalock-Taussig shunt. Then a 4-F coronary balloon angioplasty catheter carrying a 4-mm balloon was positioned across the narrowed BT shunt (D and E); note “waisting” of the balloon (D) during the initial phases of balloon inflation. Right innominate artery cineangiogram (F) following balloon angioplasty showing the open Blalock-Taussig shunt and opacification of the pulmonary artery through the shunt, although the shunt is still narrow. (Reprinted with permission.22)
inhibiting drugs. Others16’ have used aspirin and dipyridamole in the postdilatation period. The type of BT shunt constriction that responds to balloon angioplasty is not clear. The Madison experience indicates that diffusely narrowed shunts do not favorably respond, whereas discrete obstructions are likely to improve. Conclusion Based on the Madison experience and that reported by others, 159-163 balloon angioplasty of narrowed BT shunts is recommended as the procedure of choice to augment pulmonary blood flow if the patient’s size or complexity of the cardiac defect will not permit total surgical correction, but, at the same time, the child
requires palliation of systemic hypoxemia pulmonary oligemia. PULMONARY
and
ATRESIA
Pulmonary atresia may be present with or without a ventricular septal defect. Multiple palliative procedures are usually necessary’6h.‘h7 before any corrective surgery. Pulmonary atresia patients with ventricular septal defects usually have an underdeveloped main pulmonary artery and/or infundibular atresia and may not be amenable to transcatheter treatment, to be discussed below, although an occasional patient may have isolated valvar atresia. Patients with pulmonary atresia with intact ventricular septum usually have a well-developed main pulmo-
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nary artery with only valvar atresia, although some patients in this category may also have infundibular atresia. Transcatheter approaches that have potential utility in the management of valvar pulmonary atresia with intact ventricular septum will be discussed in this section. These methods could also be used in the ventricular septal defect group, provided the infundibulum and main pulmonary artery are wide open. The prognosis for patients who have pulmonary atresia with intact ventricular septum is poor with or without conventional surgical intervention.‘h”‘“8-‘70 Therefore, we suggested166,‘7’ the adoption of a comprehensive medical and surgical treatment program leading to complete surgical correction of the lesion. The objectives of such a program were (1) to relieve hypoxemia and acidosis by a timely and appropriate procedure to increase pulmonary blood flow at initial presentation (usually in the newborn period), (2) to facilitate adequate egress of blood from the right atrium, and (3) to stimulate the growth of the right ventricle. The objectives of the program can often be achieved by appropriately timed, multiple surgical procedures. These have been detailed elsewhere.‘@j Two transcatheter treatment strategies have been suggested for the management of these difficult patients:“?J7” (1) primary perforation of the atretic pulmonary valve by transcatheter methods’7’ and (2) limited opening of the pulmonary valve at surgery,‘7.7 both followed by balloon valvuloplasty. Transcatheter Peforation Valve
of Atretic Pulmonary
Perforation of the atretic pulmonary valve with a blunt wire, though feasible,174 is not generally used. Lee, Riemenschneider, and associates’75.‘7h used laser irradiation to relieve obstructed valves and create atria1 septal defects in animal models and human postmortem specimens. Arapov et al used laser for pulmonary valvotomy introperatively.‘77 Qureshi et al”’ used laser via a catheter to perforate an atretic pulmonary valve and followed this up with balloon enlargement of the pulmonary valve. They were successful in perforating the pulmonary valve with a laser (Nd-YAG laser) wire in four of the five patients in whom they tried this procedure. Perforation of the right ventricle and cardiac tamponade occurred in
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the fifth patient. Increase in the pulmonary artery pressure and decrease in right ventricular pressure occurred in all four patients. At 2- to 6-month follow-up, forward flow across the laser-opened pulmonary valve was demonstrated; there was a 50 to 70 mm Hg residual gradient across the pulmonic valve. The oxygen saturations ranged from 70% to 87%. These preliminary observations are of interest, and with further refinement of the technique and additional clinical trials, the laser techniques are likely to be useful in the management of these complex pulmonary atresia patients. Surgical Pulmonary Valvotomy Followed by Balloon Valvuloplasty
Latson and associates173 advocated limited incision (4 mm) in the atretic pulmonary valve by direct vision via the main pulmonary artery in order to allow antegrade flow and future access for balloon dilatation. They performed this procedure either at the time of the initial shunt procedure or at a subsequent sitting. They performed balloon pulmonary valvuloplasty at 2 to 12 months of age and reduced the pulmonary valvar gradients to less than 20 mm Hg. The right ventricular peak systolic pressure was less than 60% of systemic pressure. They applied this technique in four infants. Two patients had undergone complete repair, and the other two are acyanotic and have biventricular physiology. Kanh5 Sullivan,55 and their associates also attempted balloon dilatation following surgical pulmonary valvotomy for pulmonary atresia but without success. Ballerini et a176also performed balloon valvuloplasty after surgical valvotomy for pulmonary atresia with intact ventricular septum; in six patients, they reduced peak pulmonary valve gradients from 50 ? 8 mm Hg to 30 & 6 mm Hg. The Madison experience in a single patient is similar to that reported by Ballerini.76 Both the above approaches are innovative methods and may have clinical utility. Appropriate clinical trials are warranted to assess their effectiveness and safety. SUMMARY
AND CONCLUSIONS
The role of transcatheter methods in the management of pulmonary outflow tract obstruc-
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tion are discussed in this review. Balloon pulmonary valvuloplasty for relief of isolated pulmonary valve stenosis has been successfully used by many investigators and is the procedure of choice for the management of these lesions. Supravalvar pulmonic stenosis, if discrete, can be relieved by balloon dilatation. Cyanotic children with interatrial right-to-left shunts secondary to severe valvar pulmonary stenosis respond in a manner similar to that observed with isolated pulmonary valve stenosis. In these patients, balloon valvuloplasty is the treatment of choice and may be corrective in most patients. In patients with interventricular right-to-left shunting secondary to pulmonary outflow tract obstruction and in patients with narrowed BT shunts, balloon dilatation may be an effective palliative procedure in a substantial proportion of patients obviating the need for an initial or second palliative shunt. Balloon dilatation is recommended if the patient’s size or cardiac anatomy make them unsuitable for safe total surgical correction. In patients with pulmonary atresia, either initial opening of the atretic pulmonary valve by laser or by surgery with subsequent balloon dilatation are potentially beneficial in reducing the total number of surgical procedures that these children are likely to require. However, further clinical trials are needed before their general use. ACKNOWLEDGMENT The author wishes to acknowledge with thanks the contributions to this material by the past and present colleagues in pediatric cardiology and cardiovascular sur-
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gery, including Drs M. Brais, P.S. Chopra, F. Kutayli, J. Levy, M.K. Mardini, L. Solymar. M.K. Thapar. and A.D. Wilson. Thanks are also due to Nanette Kelsey for her assistance in the preparation of the manuscript.
APPENDIX 1. TECHNIQUE OF BALLOON VALVULOPLASTY IN ISOLATED PULMONARY VALVE STENOSIS The indications for catheter intervention (described previously) are usually those prescribed for surgical intervention. Once balloon dilatation is decided on (1) a No. S- to 7-F multi-A-2 (Cordis) catheter is introduced percutaneously into the femoral vein and advanced across the pulmanic valve, and then into the left pulmonary artery: (2) a 0.014- to 0.035~in J-shaped guidewire is passed through the catheter into the distal left pulmonary artery; (3) a No. 4- to 9-F balloon dilatation catheter is advanced over the guidewire and the balloon is positioned across the pulmonary valve: and (4) the balloon is inflated with diluted contrast material to approximately 3 to 5 atmospheres of pressure (Fig 29). The pressure of inflation is monitored with the help of any of the commercially available pressure gauges. The recommended duration of inflation is 5 seconds. Usually a total of three to four balloon inflations are performed 5 minutes apart. A double-balloon technique (two balloons simultaneously inflated across the stenotic region) is used when the valve annulus is too large to dilate with a commercially available single balloon: and (5) mea surement of pressure gradients across the pulmonic valve and angiographic demonstration of the relief of obstruction are performed. Recordings of heart rate, systemic pressure. and cardiac index before and after balloon dilatation are made to ensure that any change in pressure gradient is not related to a change in cardiac index but is indeed related to the procedure. The procedure is generally performed with the patient sedated (usually with a mixture of meperidine. promethazinc, and chlorpromazine, administered intramuscularly) although some cardiologists use ketamine” or general anesthesia.““,id
Fig graphic tation pulmonic of the phases which ished balloon
29. Selected cineradioframes of a balloon dilacatheter placed across the valve. Note “waisting” balloon during the initial of balloon inflation (A), is almost completely abolduring the later phases of inflation (6).
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Other aspects of importance for successfully accomplishing balloon angioplasty are as follows: 1. Difficult femoral venous access. Sometimes, it may be difficult to cannulate the femoral vein percutaneously either because of technical problems or because of femoral vein thrombosis secondary to previous catheterization and/or surgery. Cut down and isolation of the saphenous veinfemoral vein junction may be performed, and catheterization and balloon valvuloplasty can be accomplished via the saphenous venous bulb. When femoral venous access is not possible, balloon pulmonary valvuloplasty may be performed via an axillary venous55.5h or internal jugular venousi7 approach. The latter two approaches are also useful in the presence of infrahepatic interruption of the inferior vena cava with azygos or hemiazygos continuation. 2. Passing an end-hole catheter across the pulmonic valve. This may be difficult in some patients, particularly in young children and neonates. In such occasions, several maneuvers may be used: (1) use an end-hole catheter (usually a multi-A-2), position it just underneath the pulmonary valve, and advance the floppy end of a straight guidewire through the tip of the catheter into the main pulmonary artery: (2) use a balloon-wedge catheter. position it just beneath the pulmonic valve, and quickly deflate the halloon and advance the catheter into the main pulmonary artery. Failing this, use a guidewire, as described earlier; (3) use a flexible, steerable coronary guidewire through an end-hole catheter; (4) we have encountered one child in whom we could not advance any catheter across the right ventricular infundibulum because of severe infundibular constriction. In this child, administration of propranolol (0.1 mgikg intravenously (IV) slowly) made it possible to pass a catheter across the pulmonary valve and eventually balloon pulmonary valvuloplasty.r8 3. Choice of size of balloon dilatation catheter. The current recommendations are to use a balloon that is 1.2 to 1.4 times the size of the pulmonary valve annulus. These recommendations are formulated on the basis of immediatesx and follow-up results.ss,‘3 For further discussion of the reasoning behind such recommendations, the reader is referred to these publications.ss~13~L5 Balloons larger than 1.5 times the size of the pulmonary valve annulus are not
Fig 30. Selected tine frames of two balloon catheters placed across the pulmonary valve showing “waisting” of the balloons [arrows) during the initial phases of balloon inflation (A), which is completely abolished after complete inflation of the balloons (B).
151
recommended because of potential damage to the right ventricular outflow tract caused by use of large balloons.5y However. it may be advisable to use a large balloon to produce a ballooniannulus ratio of 1.5 when pulmonary valve dysplasia is present.‘” When the pulmonary valve annulus is too large to dilate with a single balloon, valvuloplasty with simultaneous inflation of two balloons across the pulmonary valve annulus (Fig 30) should be performed. When two balloons are used, the following formula is used to calculate the effective balloon sizes:
D,+Dz+n
i
;+?
1
T
where Dr and D: are diameters of the balloons used. Although the double-balloon technique is not superior to a single-balloon technique,*J”,?’ it does reduce injury to the femoral veins because smaller-sized catheters can be used. Some workersh0-63 have advocated bifoil and trefoil balloons with the idea that there will be forward flow around the balloon during balloon inflation. Although such attempts to allow forward flow during balloon inflation are laudable, there may not be any significant forward flow in view of the fact that the balloons used for pulmonary valve dilatation are larger than the valve annulus. 4. On occasion, it may be difficult to advance the balloon dilatation catheter across the pulmonicvalve. It is important to avoid kinking or looping of the guidewire to prevent such a problem. Replacement of the guidewire with an extra-stiff Amplatz guide may circumvent the problem. 5. Sometimes it may not be feasible to advance an appropriate-sized balloon dilatation catheter across the pulmonic valve even after having a guidewire across it. In such situations, we use smaller-sized 4- to 6-mm balloons on a 4. or 5-F catheter initially to predilate followed by larger. more appropriate-sized balloons. This technique is also helpful when dilating very severely stenotic pulmonary valves and in small infants.
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Fig 31. Selected cineradiographic (lateral view) frames of a balloon dilatation catheter placed across the pulmonic valve in an infant with tetralogy of Fallot. Note “waisting” of the balloon during the initial phases of balloon inflation (A), which is almost completely abolished during the later phases of balloon inflation(B). (Reprinted with permission of Wiley-Liss, a division of John Wiley & Sons, Inc.ro)
APPENDIX 2. TECHNIQUE OF BALLOON DILATATION IN PULMONARY STENOSIS WITH ATRIAL RIGHT-TO-LEFT SHUNT The procedure of balloon pulmonary valvuloplasty in this condition is exactly the same as that used for isolated valvar pulmonary stenosis, described in Appendix 1. However. the procedure may be slightly more difficult to accomplish because of greater severity of the pulmonary outflow obstruction and a more frequent association of right ventricular hypoplasia and infundibular obstruction. Sometimes, even introducing a 5-F catheter across the pulmonary valve may cause bradycardia and hypoxemia because of further obstruction to pulmonary blood flow by the catheter. In such occasions, we leave a 0.014-in guidewire (wires used for coronary arterial lesions) across the pulmonic valve and then perform rapid dilatation with a 4-F coronary balloon dilatation catheter carrying a 4-mm low-profile balloon. Subsequent to that, a more appropriate-sized balloon dilatation catheter (1.2 to 1.4 times the size of the pulmonary annulus) can be used. Such progressive dilatation technique46,‘39 should be used when dealing with severe pulmo-
Fig 32. Right innominate artery cineangiogram initially entered with the help of a 0.014-in guidewire. shunt was dilated with angiographic improvement (Reprinted with permission.rr)
nary valve stenosis patients with supra-systemic right ventricular peak systolic pressure, and in neonates and small infants after spontaneous ductal closure. At times, it may be difficult to advance a catheter across the severe infundibular obstruction secondary to valvar stenosis; administration of propranolol (0.1 mg/kg) by a slow intravenous drip may help position the catheter across the right ventricular obstruction’s and allow balloon valvuloplasty. Hypotension during balloon inflation is minimal in these children because of maintenance of systemic perfusion by right-to-left shunting across the patent foramen ovale.i”D However, when monitored by pulse oximetry, the systemic arterial oxygen saturation decreases, which returns to normal after balloon deflation.
APPENDIX 3. TECHNIQUE OF BALLOON VALVULOPLASTY FOR PATIENTS WITH PULMONARY STENOSIS AND VENTRICULAR RIGHT-TO-LEFT SHUNTS The technique of balloon group of patients is similar
showing a markedly narrowed, Then a 3-mm balloon-on-a-wire (C). Catheters carrying larger
thread-like could balloons
pulmonary valvuloplasty to that used in isolated
in this valvar
right subclavian artery (A) which was be advanced across the shunt (B) and the could not be advanced into the shunt
CATHETER
THERAPY
OF PULMONARY
pulmonic stenosis described at times. it may be more valvuloplasty in this group valve stenosis group. An across the pulmonary valve size that is 1.2 to 1.4 times annulus is recommended.sr?
STENOSIS
153
earlier in this review, although, difficult to accomplish balloon than in the simple pulmonary example of balloon catheters is shown in Fig 31. A balloon the size of the pulmonary valve
APPENDIX 4. TECHNIQUE OF BALLOON ANGIOPLASTY OF STENOSED BLALOCK-TAUSSIG SHUNTS After clinical assessment and after the usual laboratory studies suggested hypoxemia and pulmonary oligemia in association with a complex cyanotic heart defect, cardiac catheterization is performed both to confirm the clinical diagnosis and for possible balloon angioplasty. In each case, 100 U/kg of heparin (maximum 2,500 U) is administered immediately after introduction of an arterial catheter. After obtaining arterial oxygen saturation, right or left innominate artery (depending on the side of aortic arch) or subclavian artery cineangiogram is performed in order to determine the location and size of the Blalock-Taussig (BT) anastomosis. Attempts to advance a 5-F multi-A2 and/or a right coronary artery catheter into BT shunt and pulmonary artery are made. Failing this, the tip of the catheter is positioned in the mouth of the subclavian artery, or as close to it as possible. and a 0.014- to 0.035-m flexible-tip guidewire is advanced into the BT shunt and from there into the pulmonary artery. (In our previous experience with one child” with almost complete occlusion of the BT shunt [Fig 28A]. the tip of the catheter was wedged against the tip of the nipple-like blind end of the subclavian artery stump, and
the stiff end of an 0.018-in guidewire was gently threaded into the pulmonary artery and, eventually, balloon angioplasty was performed with a 4-mm balloon catheter.) Once the guidewire is positioned in the distal pulmonary artery, a low-profile balloon dilatation catheter is positioned across the narrowed BT shunt. The objective is to try to position a balloon with a diameter equivalent to the diameter of the subclavian artery. If a balloon angioplasty catheter could not be passed across the BT shunt, a balloon-on-a-wire* (2 mm or 3 mm) should be advanced across the narrowed BT shunt (Fig 32). Three successive inflations at 3 to 10 atmospheres of pressure, depending on the catheter manufacturer’s recommendations, of 5 to 10 seconds duration each is performed with a 5-minute interval in between each dilatation. The procedure of dilatation with the balloon-ona-wire and with a 4-F coronary dilation catheter can be performed through a 5-F sheath placed into the femoral artery at the beginning of the procedure. Larger balloon catheters may either be advanced via a 6-F sheath or dilatation could be performed without the use of a sheath. Fifteen minutes following the last balloon dilatation, pulmonary artery to aorta pressure pullback across the BT shunt and aortic saturation are obtained and innominate or subclavian artery cineangiogram repeated.
*The balloon-on-a-wire that we used is a USC1 Probe balloon-on-a-wire (USC1 Division of C.R. Bard, Billerica. MA).?’ Other available alteratives are ACS Hartzler Micro XR (Advanced Cardiovascular Systems, Inc., Santa Clara. CA) and Sci Med Dilating Guidewire (SCIMED Life Systems, Inc., Maple Grove, MN).
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