Balloon

Angioplasty for Congenital Mitral Stenosis

Philip J. Spevak, MD, John L. Bass, MD, Giora Ben-Shachar, MD, Peter Hesslein, MD, John F. Keane, MD, Stan Perry, MD, Lee Pyles, MD, and James E. Lock, MD

We attempted (ages 0.1 to sis. All were heart failure tion In mitral patlents. For

balloon angioplasty in 9 children 10 years) with congenital mitral stenosymptomatic wlth severe congestive and failure to thrive. Effective reducgradient was initially achieved in 7 the entire group, mean vahre gradient decreased from 14.8 f 5.0 to 8.1 f 6.7 mm (p = 0.0007) and mean valve area increased from 1.1 l 0.5 to 1s f 0.9 cm*/m* (p = 0.003). More than mild mitral regurgitation developed in 2 patients but none required surgery for mitral regurgitation. Poor gradient relief followed dilation of valves wlth unbalanced chordal attachments, with restriction to the valve apparatus as in mitral arcade, and where the obstnuSi was not purely valvar as it is with a supramftral ring. No strokes, hrfectii or deaths were ch? to the procedure. Based on these data, balloon angioplasty of congenital mitral stenosis should be considered before mitral valve replacement in younger patients and in those in whom mitral valve replacement would be problematic. (Am J Cardiol199Ot66r472-476)

From The Children’s Hospital, Department of Cardiology, Boston, Massachusetts; Department of Pediatrics, University of Minnesota Hospital and Variety Club Children’s Hospital, Minneapolis, Minnesota; and Rainbow Babies and Children’s Hospital, Cleveland, Ohio. Manuscript received July 21,1989; revised manuscript received April 9, 1990, and accepted April 10. Address for reprints: Philip J. Spevak, MD, Department of Cardiology, The Children’s Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115.

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he surgical management of congenital mitral stenosis (MS) carries significant morbidity and mortality, particularly in infants and small children. In a recent review of valve replacement in children 50%, or the degree of viously described by Grossman.2 The technique for percutaneous congenital mitral mitral regurgitation increased by 1 grade. valve dilation was similar to that previously described Paired t tests were used to compare the significance by Lock et al3 for rheumatic mitral stenosis. The initial of changes in mean transmitral gradient, mitral valve balloon size was selected to be smaller than the anulus area, cardiac output, pulmonary artery mean pressure, diameter as estimated by ultrasound or angiography. left ventricular end-diastolic pressure, degree of mitral The balloon was inflated by hand with dilute contrast regurgitation and proportional net intracardiac shunt material until any constriction of the “waist” disap- (Qp/Qs>. peared or the balloon was maximally inflated. After each dilation, the gradient was remeasured and a left RESULTS ventriculography performed to check for the presence of Early results of dilation: All patients who underwent mitral regurgitation. In general, a larger balloon cathe- catheterization for balloon dilation of congenital mitral ter was selected and the dilation procedure repeated un- stenosis had successful placement of the angioplasty til the inflated balloon was up to 30% larger than the balloon across the valve. The hemodynamic and echo-

FIGURE 1. Patient 1. Parashnal short-axis views of left vmtrick (LV) and mitral valve. Before dilation separates a major, medial orike frem a minor, more lateral orifke. A third oritice (not shown) is located lation (rfghf), the tidglng tissue is torn, resulting in a large cemmon orifice. The movement of the anttior leatkts is nearly unrestricted. RA = righthferior.

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&ff), a bridge of tissue! more apkaliy. After di(A) and posttier

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tion, the catheter crossed the more medial orifice. After dilation (Figure 1, right), there was a larger common orifice; the tissue that previously had divided the 2 smaller orifices was presumedly torn. With color mapping, flow could be seen moving through the common orifice. Gradient relief persisted 17 months after balloon angioplasty (mean Doppler gradient only 2 mm Hg) and allowed the child to remain asymptomatic. Mitral regurgitation was not present at last follow-up. Clinically, the child had considerable subjective improvement in her exercise tolerance. Her weight increased from 18.9 kg (far 3%) in the 7 months after catheterization. Patient 2, with valve morphology typical of congenital MS, had no Doppler evidence of mitral regurgitation before the procedure and by color Doppler had mild to

cardiographic data are summarized in Table II. Some reduction in mitral gradient was initially achieved in 8 of 9 patients (in 1 the gradient decreased because of diminished cardiac output and not because of increased mitral valve area). For the entire group, the mean valve gradient decreased from 14.8 f 5.0 to 8.1 f 6.7 mm His (P = 0.0007) and mean valve area increased from 1.1 f 0.5 to 1.8 f 0.9 cm2/m2 (p = 0.003). Late results of dilation: Late echocardiographic follow-up data showed persistent gradient relief in 3 patients (nos. 1, 2 and 3). Patient 1, who had a triple orifice mitral valve, had the best result, with nearly a doubling in mitral valve area despite the fact that the balloon-to-anulus ratio was the smallest of any patient. In Figure 1 (left), 2 of the orifices are displayed (the other orifice was more apically located). During dila-

TABLE

II

Hemodynamics

Before Valve Index

and

After

1 2 3 4 5 6 7 8 9 Mean

Balloon-Anulus

After

Characteristics

% Change

1.3 1.1 1.1 0.7 1.7 0.8 1.8

2.3 1.6 1.9 1.0 2.6 1.6 3.1

0.5 1.1 f0.5

0.4 1.8i0.9

77 42 79 51 53 103 72 -

* SD

PA Mean Pressure

1 2 3 4 5 6 7 8 9 Mean

and

Mean Valve Gradient (mm)

Before

Pt

Angioplasty

Area (cm*/m*)

f SD

-15 58 f 33’

Before

After

% Change

16 16 13 16 6 15 -15+ 25 11 14.8 f 5.0

6 10 3 6 4 5 8 25 6 8.1 f 6.7

61 40 77 59 33 64 50 0 43 48*21*

Mitral Regurgitation

LV End-Diastolic Pressure (mm)

(mm)

Before

After

27 40 37 40 24 44 63 57 44 41.8~1~ 12.5

23

Before

28 73 40 44.5

After

2 12 18 12 13 18 10 18 20 13.2 f 5.2

43 60

f 19.0

(grade) Before

After

1 0 0 0 1 0 1 1 1

1 1 1 1 1 2 1 1 2

4 8 11 17 14 13 16 14 20 13.0 f 4.6

Cardiac lndex(liters/min/m2)

1 2 3 4 5 6 7 8 9 Mean

Before

After

Anulus Diameter

4.3 3.7 3.5 2.8 3.5 3.1 5.6

5.9 3.4 2.7 3.1 3.9 2.6 6.7 1.4 3.7 f 1.8

34 15 12 14 12 12 13 17 11 15f7

2.4 3.6f

f SD

1.0

* Using paired t test, change from before versus after dllatton slgnlflcant at p 50% increase in valve area. In both babies the weight was >5 kg at the time of dilation. In patient 4, the gradient decreased nearly 60% and valve area increased by 50%, allowing weaning from mechanical ventilation. Late restenosis after dilation: Surprisingly, 2 patients who had an initial reduction in gradient developed worseningfailure within 2 months after balloon angioplasty. Patient 6 had MS, coarctation, subaortic stenosis and multiple ventricular septal defects. Before mitral valve dilation was performed, the child had required coarctation repair, pulmonary artery band and resection of a supramitral ring. With angioplasty, the mean gradient decreasedfrom 15 to 5 mm Hg, but increased to 13 mm Hg at later catheterization, without changesin cardiac output. This patient had moderate mitral regurgitation immediately after dilation. The mitral anulus was hypoplastic with a diameter of 12 mm, considered too small to allow valve replacement at the anular level. In addition, the normal left atria1 size complicated supraanular mitral valve replacement. After angioplasty, the anterior leaflet had a small tear; after initial relief, the gradient redeveloped and the regurgitation increased.The left atria1 volume increasedfrom 116 cmj/ /m3 before dilation to 172 cm3/m/m3 22 days later. Anulus diameter did not change over the sameinterval. The patient then underwent successfulmitral valve replacement. A 17-mm Bjork-Shiley valve was placed in the supraanular position becausethe anulus was still too small. Patient 7 also had MS with aortic coarctation and ventricular septal defect. After coarctation repair, the child continued to have severe congestive failure and had suprasystemicpulmonary artery pressure.Two left ventricular papillary muscleswere noted on ultrasound, but the chordal attachments were weighted to the larger posteromedialgroup. With balloon angioplasty, the gradient decreasedfrom 15 to 8 mm Hg. After a few weeks the patient developed worsening failure and recatheterization confirmed the clinical impression of recurrence of MS becausethe gradient had increased to 12 mm. The patient was referred for surgery. The surgeonnoted a lack of the usual interchordal spacesas well as the usual commissuresand he performed a mitral commissurotomy. This child died from infection and multisystern failure 4 months after a complicated and poorly tolerated course.At autopsy, the valve had a major posteromedial and a hypoplastic anterolateral papillary

muscle. Predominant attachments of the chordae tendineae were to the posteromedial papillary muscle group. Failed dilations: Two patients did not achieve a satisfactory initial result (nos. 8 and 9). Patient 8 had little change in the appearanceof the valve echocardiographitally. The papillary muscles were close together and, while it was not appreciated antemortem, at postmortem examination a fibrous ridge typical of mitral arcade was noted. Attempts to use a larger balloon size were unsuccessful because the balloon straddled the atria1 septum during dilation and limited full inflation. This patient was clinically unchanged after dilation, and was referred for surgery and died in the operating room after mitral valve replacement. Patient 9 had previously undergone resection of a supramitral ring and a mitral commissurotomy. Residual supra- and valvar obstruction occurred. Balloon dilation was attempted but did not increase the valve area and the child required surgery soon thereafter. A supravalvular ring was resected. A prosthetic valve had to be placed in the supraanular position becauseof the hypoplastic mitral anulus. For the entire group of patients, there was no significant change immediately after dilation in left ventricular end-diastolic pressure,pulmonary artery mean pressure or cardiac index. Complications: Two patients (nos. 6 and 9) with the smallest anuli in the group developed more than mild mitral regurgitation immediately after dilation. None of the patients had significant atria1 septal defects before dilation (1 infant had a tiny sprung foramen ovale). Consequently, all required a transseptal (Brockenbrough) approach. A small atria1 level left-toright shunt was detected by color Doppler after balloon angioplasty in 7 of 9 patients with the largest Qr,Qs being 1.2 to 1.

FtGURE

latlon. Them is prolapse of the anterior leaflet (tip of arrow) that results in incomplete coaptation of the valve leaftets and mitral tight;

regurgitation. RA = right

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LA = left atrium; atrium; S = superior.

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LV = left ventricle;

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Blood loss was estimated to exceed 10 ml/kg in 4 patients. Fluoroscopy time ranged from 61 to 135 minutes. One patient required intubation during catheterization because of respiratory acidosis. No strokes, infections or deaths were due to the procedure; both deaths in this series followed valve surgery. DISCUSSION

The management of the infant or small child with symptomatic MS is a very difficult problem. Current surgical therapy carries significant mortality and morbidity. When valve replacement is performed, surgery is in many cases palliative, since in rapidly growing children the valve will often need to be changed within 3 to 4 years.’ There are 2 previous case reports of balloon angioplasty for congenital MS. In the report of 2 cases by Kveselis et al4 the procedure was completed in 1, with stenosis being only minimally relieved with the valve area increasing 21%. Late follow-up was not available. A single case of balloon angioplasty in congenital MS in a 3-year-old child was reported by Alday and Juaneda,5 the procedure resulting in an increase of the mitral valve area, although follow-up was only 1 month. We have dilated mitral valves in 9 children with congenital MS. Although patients with true parachute mitral valves were excluded, we did dilate all nonparachute mitral valves regardless of anatomy. The procedure itself was performed with minimal morbidity and no mortality. Initial gradient relief was achieved in 7 of 9 cases. The reduction in the degree of MS was clinically effective in 5 cases, and in 3 the gradient relief has persisted >3 months, the most successful result being in a patient with a triple orifice valve. The morphology of multiple orifice mitral valve is variable, and in only a portion is there a thin central fibrous subdivision between the multiple orifices as in the patient in this series.6 Tearing of fibrous bridges could potentially result in instability of the valve leaflets and the development of mitral regurgitation. In 1 patient, while dilation did not result in longterm relief of MS, angioplasty produced mitral regurgitation that contributed to increased left atria1 size and

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facilitated supraanular placement of a mitral prosthesis. Relatively poor results were achieved in children who had “parachute-like” valves with disproportionate chordal attachments to 1 of their papillary muscles, in those with restriction of the valve apparatus as in mitral arcade, and in those with a small anulus. A satisfactory result was not achieved when obstruction was due to a supramitral ring. The results of this study must be interpreted with caution. The varying anatomic valve types, the differences in balloon sizes and limitations in precisely defining anatomy may have contributed to these variable results. The aforementioned data would support several inferences: a successful outcome from balloon dilation is unlikely in all patients with congential MS; balloon angioplasty may be more likely to achieve favorable results in patients with balanced chordal attachments and in some patients with stenotic multiple orifice valves; and, in some cases, early gradient relief may be followed by restenosis. Nonetheless, balloon angioplasty of congenital MS should be considered before mitral valve replacement in younger patients (

Balloon angioplasty for congenital mitral stenosis.

We attempted balloon angioplasty in 9 children (ages 0.1 to 10 years) with congenital mitral stenosis. All were symptomatic with severe congestive hea...
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