Surgical Repair of Congenital Aortic Stenosis

Transcription

1 Surgical Repair of Congenital Aortic Stenosis Maurice Adam, M.D., Ben F. Mitchel, M.D., Milton V. Davis, M.D., Alvis Johnson, M.D., Kathryn Willis, M.D., and Gladys J. Fashena, M.D. C ongenital aortic stenosis may be manifested by congestive heart failure, by symptoms of fatigability, headache, anginal pain, or by syncopal attacks. Unfortunately not all patients have a gradually progressive or predictable course of their disease, and sudden death is not unusual. Braverman and Gibson [l] studied 73 patients with congenital aortic stenosis who were followed for varying periods up to eight years. In this group 26 had symptoms or developed symptoms, and 6 (8%) died. Five of the deaths were sudden. Fortyone patients remained asymptomatic. Morrow et al. [4] in 1958 suggested that the ideal management of patients with congenital aortic stenosis required an accurate estimation of valve orifice size. In spite of this, not all of our patients appeared to require catheterization. Among those of our patients with congenital aortic stenosis who were asymptomatic, selection for study was made on the basis of electrocardiographic evidence of left ventricular disease. The significant findings consisted of a deep SV1 and a tall RV6, suggesting left ventricular hypertrophy, together with T wave changes. The initial peaking of TV6, suggesting increased left ventricular pressure, is followed later in the course by flattening or inversion of the T waves. These electrocardiographic findings were considered an indication for study even in the absence of symptoms or xray abnormalities. In addition to this group, we also studied those patients with syncope, angina, or progressive fatigability and those in whom xray changes were progressive. These studies consisted of right and left heart catheterization, often combined with angiocardiography. Contrast studies of the left ventricle and aorta have been used with increasing frequency to delineate many From the Divisions of Thoracic and Cardiovascular Surgery and Pediatric Cardiology, Children s Medical Center, Dallas, Tex. Presented at the Second Annual Meeting of The Society of Thoracic Surgeons, Denver, CO~O., Jan. 2426, VOL. 2, NO. 5, SEPT.,

2 ADAM ET AL. Pt. Valvular tricuspid J. K. C. J. C. E. T. T. R. R. J. N. Valvular bicuspid L. P. M. G. W. A. M. 0. A. M. A. J. M. H. L. R. D. G. R. J. K. B. D. T. J. M. Subvalvular, fused J. D. L. E. W. Subvalvular, free F. M. M. P. R. H. R. E. c. s. S. M. M. H. B. A. Supravalvular L. R. J. P. P. A. L. B. c. P. TABLE 1. SURGICAL REPAIR OF CONGENITAL AORTIC STENOSIS SYmP Systolic Gradient (mm. Hg) Associated Age toms Preop. Postop. Lesions SOb Coa. A.I., S.B.E., aortic R.V. fistula, aortica trial fistula Coa. P.S., ostium primum Stenotic bicuspid valve Periph. P.S. Valvular P.S. Corr. transposition, Coa. Results" A.I., active with cardiomegal y Ball valve: markedly improved ; diastolic murmur ; grade 1 diastolic murmur Normal ECG and xray Sudden death at 4 mo. Ball valve; improved Ball valve; improved Died, heart block, at 65th day 3 operations, improved Died, heart block, at 9 mo. Died, S.B.E. & embolus, at 5 mo. Died, S.B.E., at 9 mo. " relates to symptoms, ECG, and xray. "Damped tracing. Coa. = coarctation; S.B.E. = subacute bacterial endocarditis; A.I. = aortic insufficiency; P.S. = pulmonic stenosis. 684 THE ANNALS OF THORACIC SURGERY

3 Congenital Aortic Stenosis of the anatomical features; they are not considered necessary, however, in the typical case. The indications for surgical intervention included the presence of a systolic gradient between left ventricle and aorta of 50 mm. Hg or more. Lesser gradients were considered significant if the patient also had progressive symptoms or a history of syncope. Improvement after surgery was determined by the same criteria used to evaluate the patients preoperatively. Patients were considered improved not only on the basis of their symptoms but by resolution of the electrocardiogram toward normal. There were 34 patients operated upon (Table 1). Nineteen of these had valvular stenosis, of which 13 were bicuspid and 6 tricuspid. Ten patients had subvalvular stenosis, 8 with a separate web or fibrous ring and 2 with fibrous stenotic areas fused to and involving the valve. Five patients had supravalvular aortic stenosis. VALVULAR AORTIC STENOSIS The 19 cases of valvular stenosis ranged in age from 3 to years. Eleven were symptomatic. The others were selected because of high gradients, associated aortic insufficiency, or increasing signs by electrocardiogram and xray of severity of their disease. The preoperative systolic gradient between the left ventricular cavity and aorta ranged from 35 to 150 mm. Hg. Although sometimes eliminated by operation, more often the gradient persisted postoperatively in the range of 15 to 30 mm. Hg. Usually the larger preoperative gradients were accompanied by more severe symptoms and by somewhat larger postoperative gradients; however, exceptions were noted. Occasionally asymptomatic children were found to have large gradients, while in some symptomatic cases only small gradients were measured. Several patients were studied because of typical symptoms of angina. They were found to have no gradient and were not operated upon. None of our cases appeared to fit the description of unicommissurul aortic stenosis given by Edwards [2]. The surgical treatment of 16 patients with valvular stenosis was by incision of the commissures. Great care was taken to incise only the welldeveloped commissures and to be satisfied with less than complete elimination of the gradient. This conservative approach has largely avoided surgically created aortic insufficiency. In 3 patients marked calcification or destroyed valve tissue with associated aortic insufficiency was found which required the insertion of a StarrEdwards prosthetic ball valve. The results in this group were, for the most part, quite satisfactory. There were no operative deaths, and the 18 surviving patients are all improved. One late death occurred at 4 months postoperatively while VOL. 2, NO. 5, SEPT.,

4 ADAM ET AL. the patient was playing basketball. It is presumed that this was due to a cardiac arrhythmia. It occurred in a patient who had a rather low preoperative gradient of 40 mm. Hg due to his reduced cardiac output and congestive heart failure. In retrospect, a prosthetic valve substitution might have been a more satisfactory procedure. One survivor has definite signs of aortic insufficiency with a low diastolic pressure; 2 others have diastolic murmurs but insignificant aortic insufficiency. We have been concerned about the longterm outlook in these patients with congenital aortic stenosis in spite of the return of ECG and symptoms to normal following conservative commissurotomy. One of our patients, D. T., age 18, had an aortic valvulotomy and pulmonary valvulotomy under hypothermia at age 8. The initial results were good, but in the 2 years prior to the second surgery, the symptoms of dyspnea and fatigability had returned. One month prior to admission paroxysmal nocturnal dyspnea, hemoptysis, and shortness of breath at rest were present. Restudy of the patient revealed no gradient across the pulmonary valve; however, a gradient of 94 mm. Hg across the aortic valve and marked associated aortic insufficiency were demonstrated. A Starr Edwards ball valve replacement was performed successfully. SUBVALVULAR AORTIC STENOSIS The subvalvular group varied in age from 7 to 33 years. The range of systolic gradients was 30 to 0 mm. Hg preoperatively, and 0 to 35 mm. Hg postoperatively. Seven of the patients were symptomatic. There were numerous associated defects. Three patients had coarctations previously resected, 3 had bicuspid aortic valves, 1 had an ostium primum type of atrial septa1 defect, and in 1 subacute bacterial endocarditis had destroyed the aortic valve. Contrast studies are very helpful in demonstrating the lesion in this subvalvular group (Fig. 1). Such studies should probably be done routinely because of the high incidence of muscular stenosis and mitral valve involvement in the subaortic area reported in other series [2, 61. The operative procedure involved partial or complete excision of the web in all cases. In addition to this, valve replacement and closure of two fistulas was done in 1 case. This patient was an 1 1yearold Negro female who had been studied clinically in early 1961 and was considered not yet in need of surgery. Within several months, however, she began to have fever, congestive heart failure, and developed a continuous murmur. Blood cultures became sterile on antibiotic therapy; however, her congestive heart failure, caused by aortic insufficiency and a right sinus of Valsalvatoright ventricle fistula, was only partially controlled. Surgery in this 50pound child was undertaken in desperation; the fistulas were closed and 3 Bahnson leaflets were placed in the aortic 686 THE ANNALS OF THORACIC SURGERY

5 Congenital Aortic Stenosis FIG. 1. Subvalvular aortic stenosis. Contrast study demonstrating subvalvular web lying at an angle to the xray beam. root. Marked improvement resulted, but one month after discharge a new continuous murmur, due to a noncoronary sinus of Valsalvatoright atrial fistula appeared. This was accompanied by increased congestive heart failure. At the second operation this fistula was closed and she again improved. Several weeks after surgery, signs of aortic insufficiency developed, but she was managed medically until At this time the Bahnson cusps were removed and a No. 7 StarrEdwards aortic ballvalve prosthesis was inserted. Since then she has been asymptomatic, and her ECG and xray show marked improvement. The results of treatment of subvalvular stenosis are considered good in 6 and fair in 1. There have been 3 late deaths. One late death, at 5 months, was due to subacute bacterial endocarditis, apparently arising in the aortic suture line. This led to thrombosis, embolus with resulting stroke, and death. Two cases died from surgically induced heart block, one at 65 days, and the other at 9 months, having had a pacemaker inserted previously. In the first instance of heart block, inexperience was certainly the fault. In the second case, the block occurred despite careful efforts to avoid this complication. The mitral valve arises in what amounts to the posterior third, the membranous septum is in the anteromedial third, and the free left ventricular wall involves the anterolateral third of the tissues subadjacent to the aortic annulus. At the level of the subvalvular web there may be contraction of the mitral valve, the membranous septum, and the left ventricular wall toward the axis of the left ventricular outflow tract so that it would be easy to incise too deeply in this area. With care, however, we feel that the subvalvular webs and rings can be excised readily. There is a plane of separation which can be developed in almost every patient,,but this plane was not apparent in the 2 cases in which there was fusion of the subvalvular fibrotic area to the valve cusps. VOL. 2, NO. 5, SEPT.,

6 ADAM ET AL. SUPRA VALVULAR A OR TIC STENOSIS The patients with supravalvular aortic stenosis tended to be somewhat older: Their ages varied from 8 to 41 years. The preoperative systolic gradients were comparable to the valvular and subvalvular groups, ranging from 65 to 1 mm. Hg. The postoperative gradients were possibly a little lower, ranging from 0 to 40 mm. Hg. All of our cases were of the hourglass type, and 1 had a superimposed moderate hypoplasia of the ascending aorta (Fig. 2). Although 1 patient was possibly retarded, none of them had the typical facial appearance which often accompanies the defect as reported by William et al. [7]. All of them had additional anomalies, however, the least serious of these being a bicuspid aortic valve which was free of the area of constriction. In 1 case there was an associated pulmonary valvular stenosis, and in another, multiple peripheral pulmonary artery stenoses. One patient had corrected transposition with a previous coarctation repair. In 2 of the patients the aortic valve cusp edges were fused into the area of constriction in a similar manner. This consisted of marked fusion involving the free edge of the left coronary cusp, almost but not completely excluding this sinus of Valsalva from the aortic lumen. The right coronary cusp was less extensively adherent, and the noncoronary cusp was the least involved. The opening into the left and into the right sinus of Valsalva and thus into the coronary artery ostia could be enlarged fairly readily by what amounted to an endarterectomy of the thickened tissue of the constricted zone. The bicuspid valve of 1 patient was fibrotic, resulting in a stenosis which was unrelieved by alleviation of the supravalvular constriction. Therefore, a Bahnson leaflet was used to replace one of the two leaflets of the bicuspid valve. In the patient with associated pulmonary valvular stenosis, both lesions were treated at the same operation. FIG. 2. Supravalvular aortic stenosis, showing coronary arteries proximal to the constriction, moderate hypoplasia of ascending aorta, and unusual enlargement of innominate artery. 688 THE ANNALS OF THORACIC SURGERY

7 Congenital Aortic Stenosis In all 5 cases the aortic wall subtended by the noncoronary cusp could be expanded by a gusset placed in a vertical incision made through the constricted area of the noncoronary sinus of Valsalva, as suggested by McGoon et al. [3]. A normal aortic diameter was restored in all our cases, calculating the gusset size on the basis of caliper measurements. The gussets were extended upward along the aorta for varying distances. In the patient with hypoplasia of the aorta this was a distance of about 3 cm. above the constriction. The early results of surgery have been completely satisfactory. However, one patient died 9% months postoperatively with the sudden onset of massive aortic insufficiency due to subacute bacterial endocardit is. These results compare favorably with those reported by Peterson et al. [51. In his group of 68 nonoperated patients there were 12 deaths. The use of endarterectomy or other procedures to improve coronary circulation is considered vital in those cases with fusion of the free edge of the cusps to the area of constriction. SUMMARY 1. The basis for selection of patients with congenital aortic stenosis for study and for surgery used by the authors is presented. 2. The 34 cases treated surgically by the authors are reviewed from an anatomical and therapeutic viewpoint. 3. Surgical treatment improved 29 patients. There were 5 late deaths occurring 2 to 9 months postoperatively. 4. The anatomical considerations underlying 2 of the deaths are examined. REFERENCES 1. Braverman, I. B., and Gibson, S. The outlook for children with congenital aortic stenosis. Amer. Heart J. 53:487, Edwards, J. E. Pathology of left ventricular outflow tract obstruction. Circulation 31:586, McGoon, D. C., Mankin, H. T., Vlad, P., and Kirklin, J. W. The surgical treatment of supravalvular aortic stenosis. J. Thorac. Cardiov. Surg. 41: 1, Morrow, A. G., Sharp, E. H., and Braunwald, E. Congenital aortic stenosis. Circulation 18:91, Peterson, T. A., Todd, D. B., and Edwards, J. E. Supravalvular aortic stenosis. J. Thorac. Cardiov. Surg. 50:734, Spencer, F. C., Neill, C. A., Sank, L., and Bahnson, H. T. Anatomical variations in 46 patients with congenital aortic stenosis. Amer. Surg. 26:4, William, J. E. P., BarrattBoyes, B. G., and Lowe, J. B. Supravalvular aortic stenosis. Circulation 24: 1311, VOL. 2, NO. 5, SEPT.,

8 ADAM ET AL. DISCUSSION DR. J. L. EBRENHAFT (Iowa City, Iowa): I would like to limit my discussion to the problem of left ventricular outflow tract obstruction due to infundibular subvalvular obstruction, either of the truly hypertrophic, diffuse type, or the fibromuscular variety. These seem to be two separate entities; however, strict distinction between them is sometimes not possible. This is a very dangerous and treacherous lesion. For accurate diagnosis it is essential to have precise leftsided cardiac catheterization as well as leftsided angiocardiography to correlate the catheterization findings with the anatomical picture visualized on the radiograms. We have had experience with 23 patients who had operative procedures for subaortic stenosis. Earlier in our experience we employed the transaortic approach, but we have found it to be unsatisfactory; for this reason 14 of the 23 patients were operated by the left transatrial route. The numerous associated lesions, for instance, patent ductus arteriosus, coarctations of the aorta, and, above all, associated mitral insufficiency and anomalies of the mitral valve, can be dealt with using the transatrial approach. After detachment of the se tal leaflet of the mitral valve, excellent visualization of the left ventricular out P ow tract is obtained, and total resection of the obstructing muscle bars and scar tissue rings can be performed under direct vision. Very careful reconstruction of the detached septa1 leaflet of the mitral valve is mandatory but has not caused any difficulties in our experience. The results obtained using the transatrial approach in our hands have been far superior than by the transaortic route. We have no experience in correcting this lesion by performing a left ventriculotomy as is advocated by some. There may be very rare instances where this may be necessary, but we do not be ieve that the transventricular approach should be used as a standard operative procedure. For this particular defect, a transatrial approach avoiding left ventriculotomy has proved satisfactory. DR. ADAM: I wish to thank Dr. Ehrenhaft for his suggestions. The approach through the left atrium taking down the mitral valve is very nice and, of course, gives excellent exposure to the subaortic area. We have utilized a transleft atrial approach from the right in four of our series of seven subaortic stenosis patients and have just about given it up as being unnecessarily prolonged and involved with sewing the relatively delicate valve back in place. We have not tried the approach from the left side, however, and this may be much easier. The primary reason to use this more complicated approach is in order to get a better view, and we feel that one is able to see the subaortic zone from above if one looks with an anatomist s eye, advanced knowledge, and a bloodless heart. The case of heart block which occurred early in our series probably resulted from looking at without seeing the proper anatomy. We do study all of our subaortic stenosis patients with challenge and angiocardiography. However, we have found only one case which showed a response to the challenge suggestive of idiopathic hypertrophic subaortic stenosis. This lesion could not be demonstrated at surgery and did not persist postoperatively on restudy. 690 THE ANNALS OF THORACIC SURGERY