P
0 erative Treatment o Congenital Aortic Stenosis Neal W. Salomon, M.D., Edward B. Stinson, M.D., Philip Oyer, M.D., Jack G. Copeland, M.D., and Norman E. Shumway, M.D. ABSTRACT The operative treatment of 131 patients angioplasty of the ascending aorta as described with congenital aortic stenosis is reviewed. Of the in 1961 by McGoon [201 and Stan: [241 and their 131 patients, 77% had left ventricular outflow tract associates. Subvalvular aortic stenosis repre(LVOT) obstruction at a single level and 23%, major sents a spectrum of disease ranging from a disobstruction at more than one level. There were 3 crete membranous diaphragm to diffuse hyoperative deaths (2.3%) and 10 late deaths (7.8%). pertrophic muscular LVOT obstruction, with Twenty of the 128 discharged patients have under- the proper operative therapy dictated by the gone a second procedure and 6 a third procedure for anatomical findings. recurrent or residual LVOT obstruction. The 26 The indications for operation and surgical reoperations included 7 aortic valve replacements, 4 technique are now relatively well established, left ventricular apical-abdominal aortic (LV-AA) and recently emphasis has been placed on the valved conduits, and 15 extensive aortic valvotomies long-term analysis of late results. Although exwith or without supravalvular aortoplasty. Five of cellent clinical results are often achieved inithe 20 patients undergoing reoperation died; 4 of tially, surgical therapy in most cases is still palthese deaths occurred in patients who had valve re- liative rather than curative [27], as an increasing placement at reoperation. The 4 who received number of these patients will eventually come LV-AA conduits have sustained excellent hemo- to reoperation. dynamic and clinical results with no complications. This report presents our experience with 131 Highly satisfactory clinical results can be obtained consecutive patients with congenital aortic with minimal operative risk, regardless of the level stenosis during a 17-year period at Stanford of LVOT obstruction. Reoperation for recurrent or University Medical Center. Specific emphasis is residual LVOT obstruction, however, is compara- placed on the results following reoperation. tively more hazardous, and alternative surgical apMaterial and Methods proaches (LV-AA conduits) should be considered.
Congenital aortic stenosis is a relatively common cardiac anomaly encountered in approximately 5% of all children with congenital heart disease [12, 221. The left ventricular outflow tract (LVOT) obstruction may occur at one or more of three separate levels: valvular, subvalvular, or supravalvular. Valvular aortic stenosis is the most common cause of LVOT obstruction, and commissurotomy is the preferred initial operative treatment. Localized supravalvular aortic stenosis is best repaired by patch From the Division of Cardiovascular and Thoracic Surgery, Department of Surgery, University of Arizona Health Sciences Center, Tucson, AZ. Presented at the Fourteenth Annual Meeting of The Society of Thoracic Surgeons, Jan 23-25, 1978, Orlando, FL. Address reprint requests to Dr. Salomon, Department of Surgery, Room 4402, University of Arizona Health Sciences Center, 1501 N Campbell Ave, Tucson, AZ 85724.
One hundred thirty-one patients with congenital aortic stenosis underwent operation at Stanford University Medical Center from 1960 to 1977. One hundred were male. Patient age at operation ranged from 14 days to 25 years (mean, 10.7 k 5.7 years). Preoperatively, 79 of the 131 patients (60%) were symptomatic. Symptoms included exercise intolerance in 68, exertional dyspnea in 35, angina in 15, and syncope in 6. Seventy-seven percent (101 of 131) of the patients had LVOT obstruction at a single level: 28 subvalvular, 64 valvular, and 9 supravalvular. Twenty-three percent (30 of 131) of the patients had LVOT obstruction at more than one level. Table 1 presents a clinical summary of the patients. When both single and multiple levels of LVOT occlusion were considered together, the anatomical types of obstruction were distributed as shown in Table 2. The
452 0003-4975/78/0026-0510$01.25@ 1978 by Neal W. Salomon
453
Salomon et al: Congenital Aortic Stenosis
Table 1 . Clinical Summary of 131 Patients with Congenital Aortic Stenosis
Level Subvalvular Valvular Supravalvular Multiple
No. of Patients 28 64 9
30
Sex
Age (yr)
M
F
Mean
Range
21 51 6 22
7 13 3 8
10.6 9.2 10.1
2-22 2 wk-24 6-14 2 wk-25
11.5
Table 2 . Level of Left Ventricular Outflow Tract Obstruction in 131 Patients Level Subaortic Discrete membranous
Diffuse hypertrophic
No. of Patients 33 10
Valvular
Unicuspid Bicuspid Tricuspid Undifferentiated Supravalvular
2 78
6 4
Localized
9
Diffuse
6
single most common anatomical finding was bicuspid valvular stenosis. In patients with subaortic stenosis, a discrete membranous diaphragm was three times more prevalent than diffuse muscular hypertrophy. Localized supravalvular stenosis was a somewhat more frequent finding than diffuse stenosis or aortic root hypoplasia. Thirty-six percent of the patients had cardiomegaly on routine chest roentgenograms and 75% had left ventricular hypertrophy and strain on preoperative electrocardiography. Associated cardiac anomalies included patent ductus arteriosus in 5 patients, coarctation of the aorta in 6, subendocardial fibroelastosis in 4, coronary artery anomalies in 3, and patent foramen ovale in 2. All operations were performed through a median sternotomy. Standard techniques of cardiopulmonary bypass were utilized with either a disc or a disposable bubble-type oxygenator. Generally, moderately low flow
rates (75 to 100 ml per kilogram of body weight) and moderate systemic hypothermia (30" to 32°C) were used. Aortic cross-clamping was combined with profound topical myocardial hypothermia induced by continuous irrigation of the pericardial sac with iced normal saline at 3" to 4°C for myocardial preservation [131. An oblique curvilinear aortotomy extending into the noncoronary sinus was used for routine exposure of the aortic annulus. In cases of aortic valve stenosis, the number and extent of the commissural incisions were dictated by the anatomical findings. In general, a conservative approach was taken, with some residual gradient being accepted in preference to creating major aortic incompetence. Supravalvular stenosis was managed by extending the aortotomy across the narrowed segment and inserting a Dacron gusset as a patch aortoplasty. In some cases, actual excision of a segment of the constricting region enhanced the luminal diameter. Discrete subvalvular membranous stenosis was approached through the aortic valve with the ring being resected as completely as possible while avoiding aortic and mitral valve tissue as well as the conduction bundle. Diffuse hypertrophic subaortic stenosis was also approached transvalvularly, using either a myotomy or a more complete myectomy [21]. In 4 patients a left ventricular apicalabdominal aortic (LV-AA) conduit was constructed, the technique being similar in all cases. A 20 mm nonrigid woven Dacron tube graft containing a 20 mm glutaraldehydestabilized porcine heterograft valve (Hancock Laboratories) was anastomosed to the left ventricular apex with interrupted pledgeted mattress sutures. A conical segment of left ventricular myocardium was excised prior to the anastomosis to allow unobstructed graft inflow. The section containing the valve was brought through an incision in the diaphragm to a retroperitoneal position, and the distal end was anastomosed to the side of the infrarenal aorta. Current follow-up evaluation of all but 3 discharged patients (98%) was obtained during a two-month closing interval ending June, 1977, by direct contact with the patient, the physician, or both. At this writing the average
454 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
follow-up interval for all surviving patients was 6.4 years (range, 0.5 to 17 years).
Results Mortality There were 3 perioperative deaths (2.3%) during the initial operative procedure. Two of these deaths occurred in infants less than 1 month of age who had hypoplastic left ventricles and died of refractory left ventricular failure. The third early death was that of a 6-yearold boy with recurrent ventricular tachycardia who died from refractory ventricular arrhythmias several days following operation. There were 5 late deaths in patients who had undergone only a single operation. Two patients, aged l and 12 years, died of progressive congestive heart failure unassociated with any correctable residual lesion. The 1-year-old had severe left ventricular endocardia1 fibroelastosis, found at postmortem examination. Another 1-year-old child, who had undergone an aortic valvotomy as an infant, died suddenly at home, as did an 18-year-old boy who had undergone aortic valve commissurotomy several years before. These 2 patients represent the only sudden deaths in the entire postoperative series. Two years following aortic valvotomy, a 12-year-old boy died from sepsis thought to be secondary to intravenous heroin use. Five of the 10 deaths listed as late were in patients undergoing reoperation; 3 of these deaths actually occurred during the perioperative period and were classified as late only with respect to the initial operative procedure. One death at reoperation occurred in a 13-year-old boy 12 years following aortic valvotomy. He underwent aortic valve replacement but died of progressive left ventricular failure several days following reoperation. Death occurred in a 9-year-old boy who had undergone aortic valvotomy, resection of subvalvular stenosis, repair of coarctation, and closure of a patent ductus arteriosus at age 3 months. At reoperation, repeat commissurotomy, resection of subaortic stenosis, and patch aortoplasty were performed. The patient needed intraaortic balloon support, however, and died of severe left ventricular failure one day postoperatively. At postmortem examination there was massive left
ventricular hypertrophy, with the free wall of that ventricle being more than 7.5 cm thick. A 16-year-old boy died during his third operation (second aortic valve replacement) after endocarditis developed on a homograft valve that necessitated re-replacement of both the valve and the ascending aorta. A 14-year-old boy died of a documented cerebral embolus three months following aortic valve replacement with a Starr-Edwards prosthesis. The final death was that of a 39-year-old woman who, at age 24 years, had undergone aortic valvotomy and resection of subvalvular stenosis. Fourteen years later she required aortic and mitral valve replacement with resection of residual subaortic stenosis. Endocarditis developed with dehiscence of the mitral prosthesis, and she died following a second mitral valve replacement.
Reoperation Twenty of the 128 discharged patients (15.6%) have undergone a second operation for recurrent or residual LVOT obstruction from 1 to 15 (mean, 6.0) years after the initial operation. Six patients have had a third operation. The 26 reoperative procedures included: 7 aortic valve replacements, 4 LV-AA valved conduits, and 15 extensive aortic valvotomies with or without supravalvular aortoplasty or resection of subaortic tissue. The average age at initial operation of patients requiring a subsequent surgical procedure for LVOT obstruction was 9.2 years, which was not significantly different from the mean patient age of the group as a whole (10.7 years). Five of the 20 patients undergoing reoperation died, accounting for 38% of the total deaths. Four of these deaths occurred in patients undergoing aortic valve replacement at reoperation. In 4 patients an LV-AA valved conduit was used to relieve recurrent severe LVOT obstruction. In all 4 cases the abdominal aorta was abnormally small, never more than 1 cm in diameter. Currently, none of the patients with an LV-AA conduit is receiving anticoagulants. The first LV-AA conduit was used in a 16year-old boy who had originally undergone aortic valvotomy at age 8 years. Four years later, repeat aortic valvotomy and patch aortoplasty
455
Salomon et al: Congenital Aortic Stenosis
were necessary. Four years after that, recurrent LVOT obstruction necessitated a third procedure. Resection of residual or recurrent subvalvular stenosis, closure of a small infracristal ventricular septa1 defect (VSD), and construction of an LV-AA valved conduit were performed. Recovery was uneventful, and functional results have been excellent. A 9-year-old boy with severe subvalvular and valvular LVOT obstruction had originally undergone resection of subvalvular stenosis and commissurotomy at age 5 years. Three and one-half years later a repeat operation was necessary. One year later the patient underwent construction of an LV-AA conduit and closure of a small, probably iatrogenic supracristal VSD. Recovery was uneventful, and his postoperative functional status remains excellent. A third patient was a 12-year-old boy who had undergone staged relief of multilevel LVOT obstruction 5 years earlier. Postductal coarctation of the aorta was repaired through a left thoracotomy, and through a median sternotomy an aortic valvotomy and patch aortoplasty were performed. Recurrent LVOT obstruction necessitated reoperation. Preoperative catheterization demonstrated severe stenosis at the subvalvular, valvular, and supravalvular levels, and the patient underwent placement of a valved conduit from the left ventricular apex to the infrarenal abdominal aorta. Recovery was uneventful, and the patient continued to do well 1 year postoperatively. Several years after he had undergone two attempts at repair of severe supravalvular aortic stenosis, a 14-year-old boy had a 130 mm Hg residual gradient. The aortic root was markedly hypoplastic and not amenable to primary reconstruction. Consequently, an LV-AA conduit was constructed with good results.
$ m
Q c
5 $
100 8o
60 4o
a 20
I n n Preop
I
n
Postop
Fig 1 . Preoperative and postoperative New York Heart Association Functional Class.
Functional Class Evaluation of the preoperative and postoperative New York Heart Association Functional Classification of surviving patients (Fig 1) demonstrates marked postoperative clinical improvement. These results are encouraging in that the vast majority of these operative procedures are considered palliative because the patients are often left with residual gradients or iatrogenic aortic incompetence or both. Because of the difficulty in evaluating symptoms in small children, functional class was not assigned to patients under 5 years of age. Of the 110 remaining patients, preoperatively 56% were in Functional Class I, 39% in Class 11, and 5% in Class 111. Postoperatively, 95% were in Class I and 5% in Class 11. Hemodynamic Data Preoperative and postoperative transaortic peak systolic gradients are shown in Table 3. In general, only the more symptomatic patients had recatheterization; thus the postoperative data are heavily weighed toward patients with the least satisfactory results. This is documented by the fact that 20 of the 38 patients who were re-
Morbidity Major nonfatal postoperative complications in- Table 3 . Peak Resting Systolic Gradients Across the cluded: ventricular arrhythmias in 5 patients, Aorta Before and After Operation permanent complete heart block requiring Preop. Postop. pacemaker implantation in 1 patient, sternal Value No. of Value No. of (mm Hg) Patients (nun Hg) Patients dehiscence in 1 patient, renal failure in 1 pa- Level tient, hemorrhage requiring reexploration in 4 Subvalvular 85 26 40 8 81 60 60 30 patients, and myocardial infarction in 2 pa- Valvular ... 0 Supravalvular 79 9 tients.
456 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
c
6 Ea,
n
-
40-
0-4
Survival Reoperation-free
20 -
0
1
2 3
4
5
6 7 8 9 10 11 1 2 1 3 1 4 15 Years
Fig 2 . Patients surviving and reoperation free over a 25-year period.
v)
4-
100
C
.-a,
x 90
4-
Lc
0
1
795 4
0
,
1
,
2
,
,
3 4
,
5
,
,
,
,
,
,
,
1
~
1
6 7 8 9 10 11 1 2 1 3 1 4 1 5 Years postop
Fig 3 . All patients versus simulated survival of a normal age- and sex-matched population over a 75-year period.
f 10%. Overall actuarial survival, including reoperative statistics and perioperative mortality, demonstrate a 5-year survival of 91 f 2%, which decreases to 88 f 3% at 10 years and 76 f 8% at 15 years. These results corroborate a recent similar analysis by Lawson and co-workers [19]. An additional analysis was made comparing Actuarial Survival the entire group of patients with congenital aorBoth survival and reoperation-free event curves tic stenosis to the normal population matched were actuarially calculated for the entire group for age and sex. With prolonged follow-up, an [l](Fig 2). Three years following the initial op- increasingly significant difference in actuarial eration, 95 k 2% of the patients were reopera- survival is evident, as demonstrated in Figtion free; at 10 years, 76 f 5%; and at 15years, 59 ure 3.
catheterized underwent subsequent operation for relief of LVOT obstruction at one or more levels. In addition, transaortic gradients were measured only at rest, and no information is available with regard to exercise-induced changes in either gradient or valve area.
457 Salomon et al: Congenital Aortic Stenosis
Comment The results of this retrospective analysis of 131 consecutive patients with congenital LVOT obstruction substantiate the general safety and efficacy of surgical therapy for congenital aortic stenosis. In most instances operation can be performed with a low mortality (2.3% in this series) and a high probability of successful outcome [3, 7, 191. This and other recent studies emphasize, however, the palliative nature of operative intervention. With increasingly long follow-up, a greater proportion of patients will come to reoperation [191. At 10 years following their initial operation, 24% of the surviving patients in our series had undergone a subsequent operative procedure. Lawson and colleagues [19] reoperated on 18% of their patients within 10 years. The vast majority of reoperations are needed for residual or recurrent stenosis; iatrogenic aortic incompetence was not the primary indication for reoperation in any patient in this series. This reflects our policy of avoiding the creation or exacerbation of aortic regurgitation, even at the risk of accepting a residual gradient. It is our belief that moderate LVOT stenosis is tolerated far better than a similar degree of aortic incompetence. Two high-risk subgroups have been clearly identified. The group with the highest early mortality are infants less than 1 year old [MI. The significantly higher mortality reflects several factors. First, these infants manifest severely symptomatic congestive heart failure. Second, associated cardiac anomalies more commonly affect both early and late results, especially in patients with hypoplastic left heart and endocardia1 fibroelastosis. Third, operative repair is often more difficult and less precise than in older patients. This group represents one of the most challenging facets of congenital aortic stenosis, and although operative methods are generally well standardized, a wide variety of surgical approaches have been advocated. These include surface-induced deep hypothermia and circulatory arrest [71, closed transventricular aortic valvotomy [26], valvotomy with venous inflow occlusion [16], and conventional extracorporeal venoarterial bypass. At present there seems to be no clearcut advantage to one approach over another.
The other patient group at considerably higher than average risk are those patients who require reoperation for residual -or recurrent LVOT obstruction. It is clear that with longterm follow-up, an increasing proportion of patients will come to reoperation. The choice of the subsequent procedure will be determined by both the anatomy of the LVOT obstruction and the patient’s age and size. Five of the 20 patients (25%) undergoing a subsequent operation died, accounting for 38% of the total deaths in the series. Four of the 5 died following aortic valve replacement. In contrast, 4 patients with recurrent or residual extensive LVOT obstruction who received LV-AA conduits enjoyed relatively benign postoperative recoveries. In each case, a woven Dacron tube graft containing a glutaraldehyde-treated Hancock porcine aortic valve was inserted between the left ventricular apex and the infrarenal abdominal aorta. The concept of providing an alternative left ventricular outlet dates back to 1910, when Alexis Carrel attempted to divert blood flow from the ascending aorta using a bypass from the left ventricle to the descending aorta [6]. Subsequent experimental work by Jeger [15] and Hufnagel [14] and by Bailey [2], Donovan [ll], and Sarnoff [23] and their associates led to clinical application of this technique by Templeton in the early 1960s.* Although this experience was apparently successful, it was not widely publicized, and no further experience with the technique was reported until 1975, when Bernhard and associates [4] used a composite conduit with a rigid left ventricular inlet. Similar successful results have been reported by Dembitsky and Weldon [lo], who also used a rigid left ventricular apical stent. Their preference for a rigid stent was based partly on experimental work by Brown and co-workers [5]. More recently, Norman, Cooley, and their associates [8, 91 have described the successful clinical application of a new commercially available valved conduit that features a semirigid left ventricular apical stent. The technique used in our patients involved excision of a conical segment of the left *Templeton JY: Personal communication, 1961.
458 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
ventricular apical myocardium, beveling the incision so that the endocardia1 diameter was slightly larger than the epicardial. With Teflon-pledgeted horizontal mattress sutures of 3-0 braided polyester, the proximal end of the Dacron graft was invaginated into the elliptical apical incision. The grafts were brought through an incision in the left hemidiaphragm in a retroperitoneal position and the distal anastomosis was made end-to-side to the infrarenal aorta. The valve itself was positioned below the diaphragm. Prior to closure, simultaneous aortic and left ventricular intracavitary pressures were measured with the conduit both opened and occluded. With the conduits temporarily occluded, the mean pressure gradient between the left ventricle and aorta was 65 mm Hg; when the conduit was opened, 3 patients had no measurable peak or mean left ventricularaortic gradient. One further patient, the 12year-old boy with a very narrow abdominal aorta (approximately 6 to 8 mm in diameter), had a residual gradient of 30 mm Hg. This is the only patient who underwent postoperative catheterization and angiography. There was an 80 mm Hg peak systolic gradient between the left ventricle and the ascending aorta and a 40 mm Hg gradient between the left ventricle and the distal end of the conduit, with minimal contribution across the heterograft valve. On left ventriculography the ventricle ejected through both the apical conduit and the native aortic valve until midsystole, at which time the apical musculature obliterated the conduit opening. Semiquantitative technetium scanning suggests that approximately 60 to 70% of the left ventricular flow passes through the conduit. One year postoperatively the patient was clinically improved and scheduled to undergo follow-up catheterization. All 4 of these patients had marked cardiomegaly as well as extensive postoperative pericardial and thoracic adhesions. For these reasons, it was thought that a more satisfactory distal anastomosis with less likelihood of conduit angulation could be accomplished using the abdominal rather than the thoracic aorta. Recently there have been several reports of new surgical techniques designed to enlarge the aortic annulus in cases of annular hypopla-
sia. Konno [17] and Symbas [251 and their associates have described incising the interventricular septum and enlarging the available annulus diameter by patching both the septum and the right ventricular outflow tract. We have not yet had any experience with this technique. Attempts at determining statistically significant preoperative risk factors for overall survival as well as for the predictability of reoperation were generally inconclusive. Factors taken into consideration were: age and size at the initial operation, severity of the left ventricularaortic gradient, levels of obstruction, type of repair performed at the initial operation, presence of symptoms both before and after operation, cardiomegaly on chest roentgenography, and left ventricular hypertrophy on electrocardiography. The only variable that attained statistical significance (p < 0.05) as a risk factor for both overall survival and reoperation was patient age less than 2 years at initial operation. The 8 patients younger than 2 years old had a significantly higher mortality and probability of need for subsequent operation than did the remainder of the group. This clearly reflects both the greater severity of LVOT obstruction and the difficulty in attaining an adequate repair in this age group. In summary, when the entire spectrum of congenital aortic stenosis is considered, highly satisfactory clinical results can be obtained with minimal operative risk, regardless of the level of LVOT obstruction. The palliative nature of initial surgical repair is acknowledged, and certain high-risk situations, i.e., operating on children under 2 years of age and reoperation for recurrent or residual stenosis, must be recognized. Recent advances in the design of ventriculoaortic valved conduits and more radical reconstruction of the LVOT to allow insertion of adequate-sized prostheses may provide alternative means of relieving aortic stenosis.
References 1 . Anderson RP, Bonchek L1, Grunkemeier GL, et al: The analysis and presentation of surgical results by actuarial methods. J Surg Res 16:224, 1974 2. Bailey CP, Glover RP, O’Neill TJ, et al: Experiences with the experimental surgical relief of aortic stenosis. J Thorac Surg 20:516, 1960
459
Salomon et al: Congenital Aortic Stenosis
3. Bemhard WF, Keane JF, Fellows KE, et al: Progress and problems in the surgical management of congenital aortic stenosis. J Thorac Cardiovasc Surg 66:404, 1973 4. Bemhard WF, Poirier V, La Farge CG: Relief of congenital obstruction to left ventricular outflow with a ventricular aortic prosthesis. J Thorac Cardiovasc Surg 69:223, 1975 5. Brown JW, Myerowitz PD, Cann MS, et al: Apical-aortic anastomosis: a method for relief of diffuse left ventricular outflow obstruction. Surg Forum 25:147, 1974 6. Carrel A: On the experimental surgery of the thoracic aorta and the heart. Ann Surg 52:83, 1910 7. Chiariello L, Agosti J, Vlad P, et al: Congenital aortic stenosis: experience with 43 patients. J Thorac Cardiovasc Surg 72:182, 1976 8. Cooley DA, Norman JC, Mullins CE, et al: Left ventricle to abdominal aorta conduit for relief of aortic stenosis. Cardiovasc Dis Bull Tex Heart Inst 2:376, 1975 9. Cooley DA, Norman JD, Reul GJ, et al: Surgical treatment of left ventricular outflow tract obstruction with apico-aortic valved conduit. Surgery 80:674, 1976 10. Dembitsky WP, Weldon CS: Clinical experience with the use of a valve-bearing conduit to construct a second left ventricular outflow tract in cases of unresectable intra-ventricular obstruction. Ann Surg 184:317, 1976 11. Donovan TJ, Sarnoff SJ: Apical-aortic anastomosis for the relief of aortic stenosis. Circ Res 11:381, 1954 12. Friedman, WF: Indications for and results of surgery in congenital aortic stenosis. Adv Cardiol 17:2, 1976 13. Griepp RB, Stinson EB, Shumway NE: Profound local hypothermia for myocardial protection during open-heart surgery. J Thorac Cardiovasc Surg 66:731, 1973 14. Hufnagel CA: Aortic plastic valvular prosthesis; preliminary report. Bull Georgetown U Med Ctr 4:128, 1951 15. Jeger: Cited by Kuttner H, Chirurgische Operationslehre. Fifth edition. Leipzig, Barth, 1923, vol 2 16. Keane JF, Bemhard WF, Nadas AS: Aortic stenosis surgery in infancy. Circulation 52:1138, 1975 17. Konno S, Imai Y, Iida Y, et al: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 70:909,1975 18. Lakier JB, Lewis AB, Heymann MA, et al: Isolated aortic stenosis in the neonate: natural history and hemodynamic considerations. Circulation 50301, 1974 19. Lawson RM, Bonchek LI, Menashe V, et al: Late
20. 21.
22. 23. 24. 25.
26.
27.
results of surgery for left ventricular outflow tract obstruction in children. J Thorac Cardiovasc Surg 71:334, 1976 McGoon DC, Manlan HT, Vlad P, et al: The surgical treatment of supravalvular aortic stenosis. J Cardiovasc Surg (Torino) 41:125, 1961 Morrow AG, Fogarty TJ, Hannah H, et al: Operative treatment in idiopathic hypertrophic subaortic stenosis: techniques, and the results of preoperative and postoperative clinical and hemodynamic assessments. Circulation 37:589, 1968 Nadas AS, Fyler DC: Pediatric Cardiology. Third Edition. Philadelphia: Saunders, 1972 Sarnoff SJ, Donovan TJ, Case RB: The surgical relief of aortic stenosis by means of apical-aortic valvular anastomosis. Circulation 11:564, 1955 Starr A, Dotler C, Griswold H: Supravalvular aortic stenosis. Diagnosis and treatment. J Thorac Cardiovasc Surg 41 :134, 1961 Symbas PN, Ware RE, Hatcher CR Jr, et al: An operation for relief of severe left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 71:245, 1976 Trinkle JK, Norton JB, Richardson JD, et al: Closed aortic valvotomy and simultaneous correction of associated anomalies in infants. J Thorac Cardiovasc Surg 69:758, 1975 Wagner HR, Ellison RG, Keane JF: Clinical course in aortic stenosis. Circulation 56:Suppl 1:47, 1977
Discussion DR. FREDERICK 0.BOWMAN, JR. (New York, NY): Dr. Salomon and his colleagues are to be congratulated not only for their fine results and an excellent presentation, but for their emphasis on a real problem in patients with congenital LVOT obstruction: that is, that so many of the operations we perform primarily in this group of patients are only palliative and must be considered as such as each patient is followed through the years. Even discrete localized subvalvular stenosis, long considered to be easily repaired at primary operation, occasionally requires reoperation. Our experience has been similar to theirs. From 1960 to 1976 we operated on 100 patients aged 2 days to 16 years. Valvular stenosis accounted for 59, subvalvular for 30, and supravalvular for 11 patients in our series. Of the 44 older patients with valvular stenosis, 39 had commissurotomy, but 5 between the ages of 12 and 15 years required valve replacement. Only 3 patients in this group have required reoperation so far, but there are others in the wings. There were no operative or late deaths. Thirty percent have a degree of aortic insufficiency that is well tolerated, as in the Stanford experience.
460 The Annals of
Thoracic Surgery Vol 26 No 5 November 1978
Among the 15 infants, aged 2 days to 6 months, the operative mortality was significant: 40%. The 9 survivors have been followed 1 to 8 years. Three have mild aortic insufficiency. All are asymptomatic, with good growth and development, and no infant has yet required reoperation. We have not yet had the opportunity to try the LV-AA conduit. The authors appear to have presented a good case for it, however, and I imagine other discussants will add to it today. I would like to ask the authors about their longterm follow-up in the group with supravalvular stenosis. While we have not had to reoperate, it is my opinion that because of residual distortion of the aortic valve after patch repair of supravalvular stenosis, a large number of this group may require later reoperation. DR. ROBERT L. REPLOGLE (Chicago, IL): I want to ask the authors what their indications for operation are. Perhaps they would tell us the pressure gradient at which surgical treatment is recommended in congenital aortic stenosis. As a follow-up question, since the aortic valve in discrete subvalvular stenosis is normal, I would like to know whether they would recommend resection of a discrete subvalvular membrane at lower pressure gradients than they would for valvular stenosis?
DR. JOHN c. NORMAN (Houston, TX): I very much enjoyed this paper and was particularly impressed with the frequency and mortality of reoperation. In Houston, we have an increasing experience with creation of double-outlet left ventricles; our series is in the range of 25 to 30 patients. The point I would like to leave with you, which I would strongly suggest to the authors, is this: We started our series some 3 or 4 years ago using only a graft anastomosed to the apex of the left ventricle. In follow-up, those grafts tended to obstruct during sys-
tole. We then modified our approach to include use of a rigid polished Pyrolite prosthesis to replace the left ventricular apex, with the graft extending to the supraceliac abdominal aorta. The results are excellent (Circulation 56:62, 1977). We are pleased with this approach and are making these prostheses for other groups in the United States and elsewhere. DR. SALOMON: I thank the discussants. First, Dr. Bowman, we have not yet had any experience reoperating on patients with supravalvular stenosis, so I can’t comment specifically. I would like to mention one point in that regard, though. Initially, up to a year or so ago, we were using the usual Dacron graft material and then thought we would try some less porous fabric. We went to the expanded Teflon Gore-Tex material and have had good results using it for a patch angioplasty. With regard to Dr. Replogle’s second comment, we go for as complete a repair as possible, and we would resect the subvalvular membrane. The usual preoperative gradient is about 50 mm Hg, but of course it is highly variable. I thank Dr. Norman and certainly acknowledge his pioneering work. I am glad someone brought up the question of flexible versus rigid conduit design. The 4 patients reported here are the only cases in which we have used the LV-AA valved conduit, and we chose the flexible type. In 3 cases it proved entirely satisfactory. On the operating table we would occlude the graft and measure transaortic gradients, which were minimal across the conduit while it was open and dramatic when closed. In a patient with a very small, almost atretic infrarenal abdominal aorta, however, we did have a residual 30 to 40 mm Hg gradient that was initially attributed to the small aorta, but on a late postoperative angiogram I believe we did see late systolic compression at the left ventricular apex. I think the flexible conduit will probably give way to a rigid one so long as it is designed to be nonthrombogenic.
0 erative Treatment o Congenital Aortic Stenosis Neal W. Salomon, M.D., Edward B. Stinson, M.D., Philip Oyer, M.D., Jack G. Copeland, M.D., and Norman E. Shumway, M.D. ABSTRACT The operative treatment of 131 patients angioplasty of the ascending aorta as described with congenital aortic stenosis is reviewed. Of the in 1961 by McGoon [201 and Stan: [241 and their 131 patients, 77% had left ventricular outflow tract associates. Subvalvular aortic stenosis repre(LVOT) obstruction at a single level and 23%, major sents a spectrum of disease ranging from a disobstruction at more than one level. There were 3 crete membranous diaphragm to diffuse hyoperative deaths (2.3%) and 10 late deaths (7.8%). pertrophic muscular LVOT obstruction, with Twenty of the 128 discharged patients have under- the proper operative therapy dictated by the gone a second procedure and 6 a third procedure for anatomical findings. recurrent or residual LVOT obstruction. The 26 The indications for operation and surgical reoperations included 7 aortic valve replacements, 4 technique are now relatively well established, left ventricular apical-abdominal aortic (LV-AA) and recently emphasis has been placed on the valved conduits, and 15 extensive aortic valvotomies long-term analysis of late results. Although exwith or without supravalvular aortoplasty. Five of cellent clinical results are often achieved inithe 20 patients undergoing reoperation died; 4 of tially, surgical therapy in most cases is still palthese deaths occurred in patients who had valve re- liative rather than curative [27], as an increasing placement at reoperation. The 4 who received number of these patients will eventually come LV-AA conduits have sustained excellent hemo- to reoperation. dynamic and clinical results with no complications. This report presents our experience with 131 Highly satisfactory clinical results can be obtained consecutive patients with congenital aortic with minimal operative risk, regardless of the level stenosis during a 17-year period at Stanford of LVOT obstruction. Reoperation for recurrent or University Medical Center. Specific emphasis is residual LVOT obstruction, however, is compara- placed on the results following reoperation. tively more hazardous, and alternative surgical apMaterial and Methods proaches (LV-AA conduits) should be considered.
Congenital aortic stenosis is a relatively common cardiac anomaly encountered in approximately 5% of all children with congenital heart disease [12, 221. The left ventricular outflow tract (LVOT) obstruction may occur at one or more of three separate levels: valvular, subvalvular, or supravalvular. Valvular aortic stenosis is the most common cause of LVOT obstruction, and commissurotomy is the preferred initial operative treatment. Localized supravalvular aortic stenosis is best repaired by patch From the Division of Cardiovascular and Thoracic Surgery, Department of Surgery, University of Arizona Health Sciences Center, Tucson, AZ. Presented at the Fourteenth Annual Meeting of The Society of Thoracic Surgeons, Jan 23-25, 1978, Orlando, FL. Address reprint requests to Dr. Salomon, Department of Surgery, Room 4402, University of Arizona Health Sciences Center, 1501 N Campbell Ave, Tucson, AZ 85724.
One hundred thirty-one patients with congenital aortic stenosis underwent operation at Stanford University Medical Center from 1960 to 1977. One hundred were male. Patient age at operation ranged from 14 days to 25 years (mean, 10.7 k 5.7 years). Preoperatively, 79 of the 131 patients (60%) were symptomatic. Symptoms included exercise intolerance in 68, exertional dyspnea in 35, angina in 15, and syncope in 6. Seventy-seven percent (101 of 131) of the patients had LVOT obstruction at a single level: 28 subvalvular, 64 valvular, and 9 supravalvular. Twenty-three percent (30 of 131) of the patients had LVOT obstruction at more than one level. Table 1 presents a clinical summary of the patients. When both single and multiple levels of LVOT occlusion were considered together, the anatomical types of obstruction were distributed as shown in Table 2. The
452 0003-4975/78/0026-0510$01.25@ 1978 by Neal W. Salomon
453
Salomon et al: Congenital Aortic Stenosis
Table 1 . Clinical Summary of 131 Patients with Congenital Aortic Stenosis
Level Subvalvular Valvular Supravalvular Multiple
No. of Patients 28 64 9
30
Sex
Age (yr)
M
F
Mean
Range
21 51 6 22
7 13 3 8
10.6 9.2 10.1
2-22 2 wk-24 6-14 2 wk-25
11.5
Table 2 . Level of Left Ventricular Outflow Tract Obstruction in 131 Patients Level Subaortic Discrete membranous
Diffuse hypertrophic
No. of Patients 33 10
Valvular
Unicuspid Bicuspid Tricuspid Undifferentiated Supravalvular
2 78
6 4
Localized
9
Diffuse
6
single most common anatomical finding was bicuspid valvular stenosis. In patients with subaortic stenosis, a discrete membranous diaphragm was three times more prevalent than diffuse muscular hypertrophy. Localized supravalvular stenosis was a somewhat more frequent finding than diffuse stenosis or aortic root hypoplasia. Thirty-six percent of the patients had cardiomegaly on routine chest roentgenograms and 75% had left ventricular hypertrophy and strain on preoperative electrocardiography. Associated cardiac anomalies included patent ductus arteriosus in 5 patients, coarctation of the aorta in 6, subendocardial fibroelastosis in 4, coronary artery anomalies in 3, and patent foramen ovale in 2. All operations were performed through a median sternotomy. Standard techniques of cardiopulmonary bypass were utilized with either a disc or a disposable bubble-type oxygenator. Generally, moderately low flow
rates (75 to 100 ml per kilogram of body weight) and moderate systemic hypothermia (30" to 32°C) were used. Aortic cross-clamping was combined with profound topical myocardial hypothermia induced by continuous irrigation of the pericardial sac with iced normal saline at 3" to 4°C for myocardial preservation [131. An oblique curvilinear aortotomy extending into the noncoronary sinus was used for routine exposure of the aortic annulus. In cases of aortic valve stenosis, the number and extent of the commissural incisions were dictated by the anatomical findings. In general, a conservative approach was taken, with some residual gradient being accepted in preference to creating major aortic incompetence. Supravalvular stenosis was managed by extending the aortotomy across the narrowed segment and inserting a Dacron gusset as a patch aortoplasty. In some cases, actual excision of a segment of the constricting region enhanced the luminal diameter. Discrete subvalvular membranous stenosis was approached through the aortic valve with the ring being resected as completely as possible while avoiding aortic and mitral valve tissue as well as the conduction bundle. Diffuse hypertrophic subaortic stenosis was also approached transvalvularly, using either a myotomy or a more complete myectomy [21]. In 4 patients a left ventricular apicalabdominal aortic (LV-AA) conduit was constructed, the technique being similar in all cases. A 20 mm nonrigid woven Dacron tube graft containing a 20 mm glutaraldehydestabilized porcine heterograft valve (Hancock Laboratories) was anastomosed to the left ventricular apex with interrupted pledgeted mattress sutures. A conical segment of left ventricular myocardium was excised prior to the anastomosis to allow unobstructed graft inflow. The section containing the valve was brought through an incision in the diaphragm to a retroperitoneal position, and the distal end was anastomosed to the side of the infrarenal aorta. Current follow-up evaluation of all but 3 discharged patients (98%) was obtained during a two-month closing interval ending June, 1977, by direct contact with the patient, the physician, or both. At this writing the average
454 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
follow-up interval for all surviving patients was 6.4 years (range, 0.5 to 17 years).
Results Mortality There were 3 perioperative deaths (2.3%) during the initial operative procedure. Two of these deaths occurred in infants less than 1 month of age who had hypoplastic left ventricles and died of refractory left ventricular failure. The third early death was that of a 6-yearold boy with recurrent ventricular tachycardia who died from refractory ventricular arrhythmias several days following operation. There were 5 late deaths in patients who had undergone only a single operation. Two patients, aged l and 12 years, died of progressive congestive heart failure unassociated with any correctable residual lesion. The 1-year-old had severe left ventricular endocardia1 fibroelastosis, found at postmortem examination. Another 1-year-old child, who had undergone an aortic valvotomy as an infant, died suddenly at home, as did an 18-year-old boy who had undergone aortic valve commissurotomy several years before. These 2 patients represent the only sudden deaths in the entire postoperative series. Two years following aortic valvotomy, a 12-year-old boy died from sepsis thought to be secondary to intravenous heroin use. Five of the 10 deaths listed as late were in patients undergoing reoperation; 3 of these deaths actually occurred during the perioperative period and were classified as late only with respect to the initial operative procedure. One death at reoperation occurred in a 13-year-old boy 12 years following aortic valvotomy. He underwent aortic valve replacement but died of progressive left ventricular failure several days following reoperation. Death occurred in a 9-year-old boy who had undergone aortic valvotomy, resection of subvalvular stenosis, repair of coarctation, and closure of a patent ductus arteriosus at age 3 months. At reoperation, repeat commissurotomy, resection of subaortic stenosis, and patch aortoplasty were performed. The patient needed intraaortic balloon support, however, and died of severe left ventricular failure one day postoperatively. At postmortem examination there was massive left
ventricular hypertrophy, with the free wall of that ventricle being more than 7.5 cm thick. A 16-year-old boy died during his third operation (second aortic valve replacement) after endocarditis developed on a homograft valve that necessitated re-replacement of both the valve and the ascending aorta. A 14-year-old boy died of a documented cerebral embolus three months following aortic valve replacement with a Starr-Edwards prosthesis. The final death was that of a 39-year-old woman who, at age 24 years, had undergone aortic valvotomy and resection of subvalvular stenosis. Fourteen years later she required aortic and mitral valve replacement with resection of residual subaortic stenosis. Endocarditis developed with dehiscence of the mitral prosthesis, and she died following a second mitral valve replacement.
Reoperation Twenty of the 128 discharged patients (15.6%) have undergone a second operation for recurrent or residual LVOT obstruction from 1 to 15 (mean, 6.0) years after the initial operation. Six patients have had a third operation. The 26 reoperative procedures included: 7 aortic valve replacements, 4 LV-AA valved conduits, and 15 extensive aortic valvotomies with or without supravalvular aortoplasty or resection of subaortic tissue. The average age at initial operation of patients requiring a subsequent surgical procedure for LVOT obstruction was 9.2 years, which was not significantly different from the mean patient age of the group as a whole (10.7 years). Five of the 20 patients undergoing reoperation died, accounting for 38% of the total deaths. Four of these deaths occurred in patients undergoing aortic valve replacement at reoperation. In 4 patients an LV-AA valved conduit was used to relieve recurrent severe LVOT obstruction. In all 4 cases the abdominal aorta was abnormally small, never more than 1 cm in diameter. Currently, none of the patients with an LV-AA conduit is receiving anticoagulants. The first LV-AA conduit was used in a 16year-old boy who had originally undergone aortic valvotomy at age 8 years. Four years later, repeat aortic valvotomy and patch aortoplasty
455
Salomon et al: Congenital Aortic Stenosis
were necessary. Four years after that, recurrent LVOT obstruction necessitated a third procedure. Resection of residual or recurrent subvalvular stenosis, closure of a small infracristal ventricular septa1 defect (VSD), and construction of an LV-AA valved conduit were performed. Recovery was uneventful, and functional results have been excellent. A 9-year-old boy with severe subvalvular and valvular LVOT obstruction had originally undergone resection of subvalvular stenosis and commissurotomy at age 5 years. Three and one-half years later a repeat operation was necessary. One year later the patient underwent construction of an LV-AA conduit and closure of a small, probably iatrogenic supracristal VSD. Recovery was uneventful, and his postoperative functional status remains excellent. A third patient was a 12-year-old boy who had undergone staged relief of multilevel LVOT obstruction 5 years earlier. Postductal coarctation of the aorta was repaired through a left thoracotomy, and through a median sternotomy an aortic valvotomy and patch aortoplasty were performed. Recurrent LVOT obstruction necessitated reoperation. Preoperative catheterization demonstrated severe stenosis at the subvalvular, valvular, and supravalvular levels, and the patient underwent placement of a valved conduit from the left ventricular apex to the infrarenal abdominal aorta. Recovery was uneventful, and the patient continued to do well 1 year postoperatively. Several years after he had undergone two attempts at repair of severe supravalvular aortic stenosis, a 14-year-old boy had a 130 mm Hg residual gradient. The aortic root was markedly hypoplastic and not amenable to primary reconstruction. Consequently, an LV-AA conduit was constructed with good results.
$ m
Q c
5 $
100 8o
60 4o
a 20
I n n Preop
I
n
Postop
Fig 1 . Preoperative and postoperative New York Heart Association Functional Class.
Functional Class Evaluation of the preoperative and postoperative New York Heart Association Functional Classification of surviving patients (Fig 1) demonstrates marked postoperative clinical improvement. These results are encouraging in that the vast majority of these operative procedures are considered palliative because the patients are often left with residual gradients or iatrogenic aortic incompetence or both. Because of the difficulty in evaluating symptoms in small children, functional class was not assigned to patients under 5 years of age. Of the 110 remaining patients, preoperatively 56% were in Functional Class I, 39% in Class 11, and 5% in Class 111. Postoperatively, 95% were in Class I and 5% in Class 11. Hemodynamic Data Preoperative and postoperative transaortic peak systolic gradients are shown in Table 3. In general, only the more symptomatic patients had recatheterization; thus the postoperative data are heavily weighed toward patients with the least satisfactory results. This is documented by the fact that 20 of the 38 patients who were re-
Morbidity Major nonfatal postoperative complications in- Table 3 . Peak Resting Systolic Gradients Across the cluded: ventricular arrhythmias in 5 patients, Aorta Before and After Operation permanent complete heart block requiring Preop. Postop. pacemaker implantation in 1 patient, sternal Value No. of Value No. of (mm Hg) Patients (nun Hg) Patients dehiscence in 1 patient, renal failure in 1 pa- Level tient, hemorrhage requiring reexploration in 4 Subvalvular 85 26 40 8 81 60 60 30 patients, and myocardial infarction in 2 pa- Valvular ... 0 Supravalvular 79 9 tients.
456 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
c
6 Ea,
n
-
40-
0-4
Survival Reoperation-free
20 -
0
1
2 3
4
5
6 7 8 9 10 11 1 2 1 3 1 4 15 Years
Fig 2 . Patients surviving and reoperation free over a 25-year period.
v)
4-
100
C
.-a,
x 90
4-
Lc
0
1
795 4
0
,
1
,
2
,
,
3 4
,
5
,
,
,
,
,
,
,
1
~
1
6 7 8 9 10 11 1 2 1 3 1 4 1 5 Years postop
Fig 3 . All patients versus simulated survival of a normal age- and sex-matched population over a 75-year period.
f 10%. Overall actuarial survival, including reoperative statistics and perioperative mortality, demonstrate a 5-year survival of 91 f 2%, which decreases to 88 f 3% at 10 years and 76 f 8% at 15 years. These results corroborate a recent similar analysis by Lawson and co-workers [19]. An additional analysis was made comparing Actuarial Survival the entire group of patients with congenital aorBoth survival and reoperation-free event curves tic stenosis to the normal population matched were actuarially calculated for the entire group for age and sex. With prolonged follow-up, an [l](Fig 2). Three years following the initial op- increasingly significant difference in actuarial eration, 95 k 2% of the patients were reopera- survival is evident, as demonstrated in Figtion free; at 10 years, 76 f 5%; and at 15years, 59 ure 3.
catheterized underwent subsequent operation for relief of LVOT obstruction at one or more levels. In addition, transaortic gradients were measured only at rest, and no information is available with regard to exercise-induced changes in either gradient or valve area.
457 Salomon et al: Congenital Aortic Stenosis
Comment The results of this retrospective analysis of 131 consecutive patients with congenital LVOT obstruction substantiate the general safety and efficacy of surgical therapy for congenital aortic stenosis. In most instances operation can be performed with a low mortality (2.3% in this series) and a high probability of successful outcome [3, 7, 191. This and other recent studies emphasize, however, the palliative nature of operative intervention. With increasingly long follow-up, a greater proportion of patients will come to reoperation [191. At 10 years following their initial operation, 24% of the surviving patients in our series had undergone a subsequent operative procedure. Lawson and colleagues [19] reoperated on 18% of their patients within 10 years. The vast majority of reoperations are needed for residual or recurrent stenosis; iatrogenic aortic incompetence was not the primary indication for reoperation in any patient in this series. This reflects our policy of avoiding the creation or exacerbation of aortic regurgitation, even at the risk of accepting a residual gradient. It is our belief that moderate LVOT stenosis is tolerated far better than a similar degree of aortic incompetence. Two high-risk subgroups have been clearly identified. The group with the highest early mortality are infants less than 1 year old [MI. The significantly higher mortality reflects several factors. First, these infants manifest severely symptomatic congestive heart failure. Second, associated cardiac anomalies more commonly affect both early and late results, especially in patients with hypoplastic left heart and endocardia1 fibroelastosis. Third, operative repair is often more difficult and less precise than in older patients. This group represents one of the most challenging facets of congenital aortic stenosis, and although operative methods are generally well standardized, a wide variety of surgical approaches have been advocated. These include surface-induced deep hypothermia and circulatory arrest [71, closed transventricular aortic valvotomy [26], valvotomy with venous inflow occlusion [16], and conventional extracorporeal venoarterial bypass. At present there seems to be no clearcut advantage to one approach over another.
The other patient group at considerably higher than average risk are those patients who require reoperation for residual -or recurrent LVOT obstruction. It is clear that with longterm follow-up, an increasing proportion of patients will come to reoperation. The choice of the subsequent procedure will be determined by both the anatomy of the LVOT obstruction and the patient’s age and size. Five of the 20 patients (25%) undergoing a subsequent operation died, accounting for 38% of the total deaths in the series. Four of the 5 died following aortic valve replacement. In contrast, 4 patients with recurrent or residual extensive LVOT obstruction who received LV-AA conduits enjoyed relatively benign postoperative recoveries. In each case, a woven Dacron tube graft containing a glutaraldehyde-treated Hancock porcine aortic valve was inserted between the left ventricular apex and the infrarenal abdominal aorta. The concept of providing an alternative left ventricular outlet dates back to 1910, when Alexis Carrel attempted to divert blood flow from the ascending aorta using a bypass from the left ventricle to the descending aorta [6]. Subsequent experimental work by Jeger [15] and Hufnagel [14] and by Bailey [2], Donovan [ll], and Sarnoff [23] and their associates led to clinical application of this technique by Templeton in the early 1960s.* Although this experience was apparently successful, it was not widely publicized, and no further experience with the technique was reported until 1975, when Bernhard and associates [4] used a composite conduit with a rigid left ventricular inlet. Similar successful results have been reported by Dembitsky and Weldon [lo], who also used a rigid left ventricular apical stent. Their preference for a rigid stent was based partly on experimental work by Brown and co-workers [5]. More recently, Norman, Cooley, and their associates [8, 91 have described the successful clinical application of a new commercially available valved conduit that features a semirigid left ventricular apical stent. The technique used in our patients involved excision of a conical segment of the left *Templeton JY: Personal communication, 1961.
458 The Annals of Thoracic Surgery Vol 26 No 5 November 1978
ventricular apical myocardium, beveling the incision so that the endocardia1 diameter was slightly larger than the epicardial. With Teflon-pledgeted horizontal mattress sutures of 3-0 braided polyester, the proximal end of the Dacron graft was invaginated into the elliptical apical incision. The grafts were brought through an incision in the left hemidiaphragm in a retroperitoneal position and the distal anastomosis was made end-to-side to the infrarenal aorta. The valve itself was positioned below the diaphragm. Prior to closure, simultaneous aortic and left ventricular intracavitary pressures were measured with the conduit both opened and occluded. With the conduits temporarily occluded, the mean pressure gradient between the left ventricle and aorta was 65 mm Hg; when the conduit was opened, 3 patients had no measurable peak or mean left ventricularaortic gradient. One further patient, the 12year-old boy with a very narrow abdominal aorta (approximately 6 to 8 mm in diameter), had a residual gradient of 30 mm Hg. This is the only patient who underwent postoperative catheterization and angiography. There was an 80 mm Hg peak systolic gradient between the left ventricle and the ascending aorta and a 40 mm Hg gradient between the left ventricle and the distal end of the conduit, with minimal contribution across the heterograft valve. On left ventriculography the ventricle ejected through both the apical conduit and the native aortic valve until midsystole, at which time the apical musculature obliterated the conduit opening. Semiquantitative technetium scanning suggests that approximately 60 to 70% of the left ventricular flow passes through the conduit. One year postoperatively the patient was clinically improved and scheduled to undergo follow-up catheterization. All 4 of these patients had marked cardiomegaly as well as extensive postoperative pericardial and thoracic adhesions. For these reasons, it was thought that a more satisfactory distal anastomosis with less likelihood of conduit angulation could be accomplished using the abdominal rather than the thoracic aorta. Recently there have been several reports of new surgical techniques designed to enlarge the aortic annulus in cases of annular hypopla-
sia. Konno [17] and Symbas [251 and their associates have described incising the interventricular septum and enlarging the available annulus diameter by patching both the septum and the right ventricular outflow tract. We have not yet had any experience with this technique. Attempts at determining statistically significant preoperative risk factors for overall survival as well as for the predictability of reoperation were generally inconclusive. Factors taken into consideration were: age and size at the initial operation, severity of the left ventricularaortic gradient, levels of obstruction, type of repair performed at the initial operation, presence of symptoms both before and after operation, cardiomegaly on chest roentgenography, and left ventricular hypertrophy on electrocardiography. The only variable that attained statistical significance (p < 0.05) as a risk factor for both overall survival and reoperation was patient age less than 2 years at initial operation. The 8 patients younger than 2 years old had a significantly higher mortality and probability of need for subsequent operation than did the remainder of the group. This clearly reflects both the greater severity of LVOT obstruction and the difficulty in attaining an adequate repair in this age group. In summary, when the entire spectrum of congenital aortic stenosis is considered, highly satisfactory clinical results can be obtained with minimal operative risk, regardless of the level of LVOT obstruction. The palliative nature of initial surgical repair is acknowledged, and certain high-risk situations, i.e., operating on children under 2 years of age and reoperation for recurrent or residual stenosis, must be recognized. Recent advances in the design of ventriculoaortic valved conduits and more radical reconstruction of the LVOT to allow insertion of adequate-sized prostheses may provide alternative means of relieving aortic stenosis.
References 1 . Anderson RP, Bonchek L1, Grunkemeier GL, et al: The analysis and presentation of surgical results by actuarial methods. J Surg Res 16:224, 1974 2. Bailey CP, Glover RP, O’Neill TJ, et al: Experiences with the experimental surgical relief of aortic stenosis. J Thorac Surg 20:516, 1960
459
Salomon et al: Congenital Aortic Stenosis
3. Bemhard WF, Keane JF, Fellows KE, et al: Progress and problems in the surgical management of congenital aortic stenosis. J Thorac Cardiovasc Surg 66:404, 1973 4. Bemhard WF, Poirier V, La Farge CG: Relief of congenital obstruction to left ventricular outflow with a ventricular aortic prosthesis. J Thorac Cardiovasc Surg 69:223, 1975 5. Brown JW, Myerowitz PD, Cann MS, et al: Apical-aortic anastomosis: a method for relief of diffuse left ventricular outflow obstruction. Surg Forum 25:147, 1974 6. Carrel A: On the experimental surgery of the thoracic aorta and the heart. Ann Surg 52:83, 1910 7. Chiariello L, Agosti J, Vlad P, et al: Congenital aortic stenosis: experience with 43 patients. J Thorac Cardiovasc Surg 72:182, 1976 8. Cooley DA, Norman JC, Mullins CE, et al: Left ventricle to abdominal aorta conduit for relief of aortic stenosis. Cardiovasc Dis Bull Tex Heart Inst 2:376, 1975 9. Cooley DA, Norman JD, Reul GJ, et al: Surgical treatment of left ventricular outflow tract obstruction with apico-aortic valved conduit. Surgery 80:674, 1976 10. Dembitsky WP, Weldon CS: Clinical experience with the use of a valve-bearing conduit to construct a second left ventricular outflow tract in cases of unresectable intra-ventricular obstruction. Ann Surg 184:317, 1976 11. Donovan TJ, Sarnoff SJ: Apical-aortic anastomosis for the relief of aortic stenosis. Circ Res 11:381, 1954 12. Friedman, WF: Indications for and results of surgery in congenital aortic stenosis. Adv Cardiol 17:2, 1976 13. Griepp RB, Stinson EB, Shumway NE: Profound local hypothermia for myocardial protection during open-heart surgery. J Thorac Cardiovasc Surg 66:731, 1973 14. Hufnagel CA: Aortic plastic valvular prosthesis; preliminary report. Bull Georgetown U Med Ctr 4:128, 1951 15. Jeger: Cited by Kuttner H, Chirurgische Operationslehre. Fifth edition. Leipzig, Barth, 1923, vol 2 16. Keane JF, Bemhard WF, Nadas AS: Aortic stenosis surgery in infancy. Circulation 52:1138, 1975 17. Konno S, Imai Y, Iida Y, et al: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J Thorac Cardiovasc Surg 70:909,1975 18. Lakier JB, Lewis AB, Heymann MA, et al: Isolated aortic stenosis in the neonate: natural history and hemodynamic considerations. Circulation 50301, 1974 19. Lawson RM, Bonchek LI, Menashe V, et al: Late
20. 21.
22. 23. 24. 25.
26.
27.
results of surgery for left ventricular outflow tract obstruction in children. J Thorac Cardiovasc Surg 71:334, 1976 McGoon DC, Manlan HT, Vlad P, et al: The surgical treatment of supravalvular aortic stenosis. J Cardiovasc Surg (Torino) 41:125, 1961 Morrow AG, Fogarty TJ, Hannah H, et al: Operative treatment in idiopathic hypertrophic subaortic stenosis: techniques, and the results of preoperative and postoperative clinical and hemodynamic assessments. Circulation 37:589, 1968 Nadas AS, Fyler DC: Pediatric Cardiology. Third Edition. Philadelphia: Saunders, 1972 Sarnoff SJ, Donovan TJ, Case RB: The surgical relief of aortic stenosis by means of apical-aortic valvular anastomosis. Circulation 11:564, 1955 Starr A, Dotler C, Griswold H: Supravalvular aortic stenosis. Diagnosis and treatment. J Thorac Cardiovasc Surg 41 :134, 1961 Symbas PN, Ware RE, Hatcher CR Jr, et al: An operation for relief of severe left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 71:245, 1976 Trinkle JK, Norton JB, Richardson JD, et al: Closed aortic valvotomy and simultaneous correction of associated anomalies in infants. J Thorac Cardiovasc Surg 69:758, 1975 Wagner HR, Ellison RG, Keane JF: Clinical course in aortic stenosis. Circulation 56:Suppl 1:47, 1977
Discussion DR. FREDERICK 0.BOWMAN, JR. (New York, NY): Dr. Salomon and his colleagues are to be congratulated not only for their fine results and an excellent presentation, but for their emphasis on a real problem in patients with congenital LVOT obstruction: that is, that so many of the operations we perform primarily in this group of patients are only palliative and must be considered as such as each patient is followed through the years. Even discrete localized subvalvular stenosis, long considered to be easily repaired at primary operation, occasionally requires reoperation. Our experience has been similar to theirs. From 1960 to 1976 we operated on 100 patients aged 2 days to 16 years. Valvular stenosis accounted for 59, subvalvular for 30, and supravalvular for 11 patients in our series. Of the 44 older patients with valvular stenosis, 39 had commissurotomy, but 5 between the ages of 12 and 15 years required valve replacement. Only 3 patients in this group have required reoperation so far, but there are others in the wings. There were no operative or late deaths. Thirty percent have a degree of aortic insufficiency that is well tolerated, as in the Stanford experience.
460 The Annals of
Thoracic Surgery Vol 26 No 5 November 1978
Among the 15 infants, aged 2 days to 6 months, the operative mortality was significant: 40%. The 9 survivors have been followed 1 to 8 years. Three have mild aortic insufficiency. All are asymptomatic, with good growth and development, and no infant has yet required reoperation. We have not yet had the opportunity to try the LV-AA conduit. The authors appear to have presented a good case for it, however, and I imagine other discussants will add to it today. I would like to ask the authors about their longterm follow-up in the group with supravalvular stenosis. While we have not had to reoperate, it is my opinion that because of residual distortion of the aortic valve after patch repair of supravalvular stenosis, a large number of this group may require later reoperation. DR. ROBERT L. REPLOGLE (Chicago, IL): I want to ask the authors what their indications for operation are. Perhaps they would tell us the pressure gradient at which surgical treatment is recommended in congenital aortic stenosis. As a follow-up question, since the aortic valve in discrete subvalvular stenosis is normal, I would like to know whether they would recommend resection of a discrete subvalvular membrane at lower pressure gradients than they would for valvular stenosis?
DR. JOHN c. NORMAN (Houston, TX): I very much enjoyed this paper and was particularly impressed with the frequency and mortality of reoperation. In Houston, we have an increasing experience with creation of double-outlet left ventricles; our series is in the range of 25 to 30 patients. The point I would like to leave with you, which I would strongly suggest to the authors, is this: We started our series some 3 or 4 years ago using only a graft anastomosed to the apex of the left ventricle. In follow-up, those grafts tended to obstruct during sys-
tole. We then modified our approach to include use of a rigid polished Pyrolite prosthesis to replace the left ventricular apex, with the graft extending to the supraceliac abdominal aorta. The results are excellent (Circulation 56:62, 1977). We are pleased with this approach and are making these prostheses for other groups in the United States and elsewhere. DR. SALOMON: I thank the discussants. First, Dr. Bowman, we have not yet had any experience reoperating on patients with supravalvular stenosis, so I can’t comment specifically. I would like to mention one point in that regard, though. Initially, up to a year or so ago, we were using the usual Dacron graft material and then thought we would try some less porous fabric. We went to the expanded Teflon Gore-Tex material and have had good results using it for a patch angioplasty. With regard to Dr. Replogle’s second comment, we go for as complete a repair as possible, and we would resect the subvalvular membrane. The usual preoperative gradient is about 50 mm Hg, but of course it is highly variable. I thank Dr. Norman and certainly acknowledge his pioneering work. I am glad someone brought up the question of flexible versus rigid conduit design. The 4 patients reported here are the only cases in which we have used the LV-AA valved conduit, and we chose the flexible type. In 3 cases it proved entirely satisfactory. On the operating table we would occlude the graft and measure transaortic gradients, which were minimal across the conduit while it was open and dramatic when closed. In a patient with a very small, almost atretic infrarenal abdominal aorta, however, we did have a residual 30 to 40 mm Hg gradient that was initially attributed to the small aorta, but on a late postoperative angiogram I believe we did see late systolic compression at the left ventricular apex. I think the flexible conduit will probably give way to a rigid one so long as it is designed to be nonthrombogenic.
