The Surgical Treatment of Tetralogy of Fallot

Transcription

1 COLLECTIVE REVIEW The Surgical Treatment of Tetralogy of Fallot H. E. Sinchez, M.D., D.Sc., E. M. Cornish, B.Sc.(Hons), M.B., Ch.B., Feng Chu Shih, M.D., J. de Nobrega, F.R.C.S., J. Hassoulas, M.Med.(Cape Town), J. Netto, M.D., R. E. Thornington, F.F.A.(S.A.), and C. N. Barnard, M.D., Ph.D., D.Sc.(Hon Causa) ABSTRACT This is a review of the last 307 patients with tetralogy of Fallot who were operated on in our unit at Groote Schuur Hospital and Red Cross War Memorial Children's Hospital. Complete repair was undertaken in 301 patients, and shunts were performed in 6 children. There were 17 hospital deaths and 1 late death. The mortality was 5.5% for children less than 12 years old and 6.6% in patients between 12 and 20 years old. During this study period, there was a change in our policy as to when complete repair should be attempted. At present, we perform systemic-pulmonary shunts in patients less than 6 months old and delay complete repair until the child is 2 years old. In deciding whether a shunt should precede complete repair, our experience has shown that age is not as important a consideration as the anatomy of the outflow tract of the right ventricle and pulmonary arteries. Tetralogy of Fallot is a common cardiac malformation, accounting for about 20% of all congenital operations performed in our unit [l-41. Disregarding minor variations in the definition of this defect, it is agreed, in general, that two fundamental malformations are present: a large, unrestrictive ventricular septa1 defect (VSD) and severe obstruction to the outflow of the right ventricle. The position of the VSD in tetralogy of Fallot is nearly always constant; it involves the membranous area of the septum, just below the aortic valve, and is slightly more ventral in its location than the isolated VSD. Occasionally the defect may extend into the supracristal area of the septum, and very rarely it may be supracristal only. The obstruction to the outflow tract of the right ventricle is due to pulmonary stenosis, which is partly or wholly infundibular, with or without underdevelopment of the outflow tract. This underdevelopment may involve the whole or a portion of the outflow from the infundibular ostium to the branches of the pulmonary arteries. Hemodynamics A large, unrestrictive VSD and severe obstruction to the outflow of the right ventricle produce equal pressures in From the Cardiac Unit and the Department of Anaesthetics (RET), Gmte Schuur Hospital and Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, Republic of South Africa. Address correspondence to Dr. Sdnchez, Department of Cardiac Surgery, Groote Schuur Hospital, Observatory, Cape Town, Republic of South Africa. the right and left ventricles. Hemodynamically, this results in a single pumping chamber with two resistances: the systemic resistance and the resistance posed by the right ventricular obstruction. The more severe the right ventricular obstruction, the greater the right-to-left shunt, the greater the cyanosis, and the smaller the blood flow into the lungs. Thus, the large, unrestrictive VSD functions as an escape mechanism, and the structural changes that result are of great importance in planning the surgical repair. One of these changes is hypertrophy of the right ventricle. Right ventricular hypertrophy develops only until it can overcome the systemic resistance. This contrasts with pulmonary artery stenosis in which, with an intact ventricular septum, the hypertrophy of the right ventricle is progressive in an attempt to overcome the resistance caused by the pulmonary valve obstruction. Another structural change is failure of the outflow tract of the right ventricle to develop adequately. Because of the poor flow through these anatomical areas and in an attempt to improve the pulmonary blood flow, a bronchial collateral system develops [l-51. The more severe the obstruction, the richer this collateral system. Indications More than 25 years have elapsed since total repair of tetralogy of Fallot was reported by Lillehei and colleagues [6] and demonstrated to be a feasible, low-risk operation by Kirklin and associates (71. Whatever approach is taken, surgical intervention plays an extremely important role in tetralogy of Fallot. The life expectancy without operation is very poor: 25 to 30% of patients will die within a year, 40% within 3 years, and only 30 to 35% will live longer. The proper timing of the surgical intervention and the choice of surgical procedure are based on an understanding of the spectrum of anatomical and physiological conditions that can occur. Although small size, young age, and severity of hypoxemia may correlate with increased risk of primary total repair, the most crucial variable appears to be the degree of hypoplasia of the main and branch pulmonary arteries and therefore the capacity of the pulmonary arteries. A poorly developed pulmonary arterial system will not accommodate the total cardiac output resulting from closure of the VSD. This causes right ventricular failure and death from low cardiac output. A number of methods have been developed to designate patients with a hypoplastic pulmonary arterial system. One involves the ratio of the main pulmonary ar- 431

2 ~ ~ 432 The Annals of Thoracic Surgery Vol 37 No 5 May 1984 tery to the ascending aorta. This ratio should be equal to or more than 0.3. If it is less than 0.3, palliative operation is performed. Another method uses the ratio of the right pulmonary artery to the ascending aorta. If the ratio is less than 0.3, initial palliation is undertaken. Finally, Pacific0 and colleagues [8] have described a formula using the ratio of the right and left pulmonary arteries to the descending thoracic aorta. In the presence of an adequate pulmonary artery, our contraindications to total repair in infants are as follows: (1) an abnormal coronary artery; (2) a single pulmonary artery; and (3) a patient less than 6 months of age in whom a patch is needed across the pulmonary valve ring. In the experience of our cardiac clinic, pulmonary incompetence is not well tolerated in small babies. The abnormal origin of the coronary arteries is a contraindication for total repair only in very small infants, not for older patients. Other authors [9-121, however, do not consider this a contraindication. Material and Methods Between January, 1974, and December, 1981, 307 patients underwent consecutive procedures for repair of tetralogy of Fallot at Groote Schuur Hospital and Red Cross War Memorial Children s Hospital in Cape Town. There were 184 male and 123 female patients. Nine patients were less than 6 months old; 18 were less than l year old; 22 were less than 2 years of age; and the rest were older than 2 years. Cyanosis was present in 285 patients; 22 were acyanotic. The VSD was in the membranous area in 294 patients and in the supracristal region in 7. Associated defects are listed in Table 1. Complete repair was performed in 301 patients. In the other 6, systemic-pulmonary shunts were done. Previous operations had been performed in 20 patients: 11 had Blalock-Taussig shunts and 9, Waterston shunts. Valvular obstruction was found in 3 patients, isolated infundibular obstruction in 104, infundibular and valvular obstruction in 155, and hypoplasia of the main pulmonary artery with different degrees of narrowing of its two branches in 45 (Figure). Table 1. Associated Defects among 307 Patients with Tetralogy of Fallot Defect Atrial septal defect 15 Patent foramen ovale 27 Patent ductus arteriosus 6 Ostium primum defect 4 Complete atrioventricular canal 1 Hemitruncus 1 Hypertrophic obstructive cardiomyopathy 1 Multiple ventricular septal defects 5 Absent left pulmonary artery 2 No. of Patients v) 70- I L 55. LL 50. a W m z s m. 7-12m m m. 5 a TRANSANNULAR GUSSET RIGHT VENTRICULAR GUSSET 10-13y. r14y. Number of patients requiring outpow tract gussets compared with age at operation. Surgical Procedure CHOICE OF PALLIATIVE PROCEDURE. We have detailed the reasoning underlying our choice of systemic-pulmonary shunts. In the last 3 years, it has been our policy to perform only Blalock-Taussig shunts or a modified shunt with a 5 mm Gore-Tex graft. For multiple reasons, use of the Waterston shunt has been abandoned. Since we adopted this policy, we have performed the Blalock- Taussig shunt with no deaths [5, 12, 13-17]. All patients receive systemic heparinization (heparin, 1 mg per kilogram of body weight) before the shunt is performed. The heparin is never reversed. A small pulmonary artery is not a contraindication; we have made shunts in pulmonary arteries about 3 mm in diameter. The Blalock-Taussig shunt is performed using the subclavian artery on the side opposite to the aortic arch. The incision in the pulmonary artery is always made longitudinally. In patients with tetralogy of Fallot, there is an additional way to increase pulmonary blood flow, that is, to place a patch across the pulmonary annulus, either leaving the VSD open or partially closing it with a perforated patch. This approach can result in symmetrical growth of the pulmonary arteries. More time will be necessary to determine how this method of palliation compares with the classic Blalock-Taussig shunt. CLOSURE OF SYSTEMIC PULMONARY SHUNTS. The patency of shunts should be confirmed at catheterization, because the presence of a continuing murmur, especially in older patients, may be due to bronchial collaterals and does not indicate a patent shunt.

3 433 Collective Review: Sanchez et al: Tetralogy of Fallot The approach to the Blalock shunt on the left side is extrapericardial, following the left pulmonary artery or the aortic arch or both. The dissection is guided by the palpable thrill. The right-sided Blalock shunt is usually easier to find. The approach is intrapericardial, between the superior vena cava and the ascending aorta. In both approaches, the subclavian artery is dissected and encircled with a ligature. It is tied after cardiopulmonary bypass is begun. The approach for a Waterston shunt can usually be accomplished through the ascending aorta. If the right pulmonary artery is kinked or narrowed, it should be detached from the aorta and patched with pericardium if necessary [ COMPLETE REPAIR OF TETRALOGY OF FALLOT. The success of this operation depends on four factors. These are (1) adequate selection of the patient; (2) adequate repair of the defects present; (3) maximal protection of the myocardium; and (4) maintenance of a normal internal environment before, during, and after operation. In children weighing less than 10 kg, the operation is performed using surface cooling, circulatory arrest, and limited cardiopulmonary bypass. In patients weighing more than 10 kg, conventional total cardiopulmonary bypass with moderate or deep hypothermia is used. Cold crystalloid cardioplegic arrest plus local hypothermia at 10 C is our method of myocardial preservation. Relieving the resistance to right ventricular emptying is an essential component of a successful repair. If possible, it is desirable to achieve this without producing pulmonary incompetence. However, relief of the outflow obstruction is more important than avoidance of pulmonary incompetence. In our experience, the creation of pulmonary incompetence has not proven a serious disadvantage, except in patients with an absent left or right pulmonary artery. These patients are left with a competent pulmonary valve. Our methods undergo continual evaluation in order to predict the necessity of a transannular patch. Enlargement of the outflow tract is performed with a pericardial patch. In patients in whom an abnormal coronary artery, usually the left anterior descending coronary artery originating in the right coronary artery, crosses the infundibulum and enlargement of this area is required, we relieve the infundibular and valvular obstruction and then put a graft between the right ventricle and main pulmonary artery to relieve the residual obstruction. The size of the graft is chosen according to the internal infundibular and valvular obstruction, so that the final outflow will be a combination of both. In this way we bypass the abnormal coronary artery. We prefer this method to that of cutting the coronary artery and doing a coronary artery bypass graft. The VSD is large, usually the diameter of the ascending aorta, and closure is always done with a prosthetic patch using interrupted sutures. The bundle lies on the left side of the septum as it reaches the level of the VSD. The incision in the infundibulum is transverse or oblique; a vertical incision is made when it is necessary to enlarge the outflow tract. Prior to decannulation, pressures are measured in the right ventricle and other chambers. An acceptable ratio of right ventricular to left ventricular pressure should be less than In our experience, patients with a ratio of greater than 0.65 but less than 1.00 immediately after repair, without patch-graft enlargement, survive the early postoperative period. In the late postoperative period, we are concerned if the right VentricularAeft ventricular pressure ratio is high (greater than 0.60), for that will result in diminished exercise tolerance (1, 2, 8-11, 18-21]. Results Hospital Mortality The overall hospital mortality was 5.5% (17 patients) and was highest in patients between 7 and 12 months of age (5 deaths among 18 patients, or 28%) (Table 2). There was 1 late death, which occurred 4 months postoperatively. Causes of death are listed in Table 3. There was no relationship between previous systemic pulmonary shunts and hospital mortality. An 8-year-old patient died of undiagnosed total anomalous pulmonary venous drainage of the supracardiac type. The condition was not noted at catheterization or at operation. Two patients, 10 months and 2 years old, died of "pump lung" or respiratory distress syndrome. Five patients died of low cardiac output due to residual obstruction at the level of the outflow tract. They also had small pulmonary arteries. These patients were 18 months, 4 years (2 patients), 5 years, and 16 years old. A 4-year-old child died of low cardiac output due to a residual VSD (disruption of the patch). Another patient, 9 months old, died of an acute residual VSD and low cardiac output. One 8-month-old infant died of low cardiac output and pulmonary edema, both due to multiple VSDs that were not diagnosed. Two patients, 10 months and 5 years old, died of low cardiac output due to peripheral pulmonary artery obstruction caused by thrombosis of the small branches of the pulmonary arteries. Two patients died of iatrogenic causes. A 14-year-old teenager experienced hyperpotassemia. In the other, a 9-month-old infant, an acute pneumothorax developed Table 2. Correlation between Age and Number of Deaths among 307 Patients with Tetralogy of Fallot Deaths No. of Age Patients Early Late 0-6 mo 7-12 mo mo mo 5-10 yr yr 314 yr Total (5.5%)

4 434 The Annals of Thoracic Surgery Vol 37 No 5 May 1984 Table 3. Causes of Early and Late Deaths Patient No. Age Cause of Death EARLY DEATHS 1 8 Y' 2 10 mo 3 16 yr 4 2 Y' 5 5 Yr 6 9 mo 7 10 mo 8 3 Y' 9 18 mo 10 9 mo 11 4 Y' 12 8 mo 13 5 Y' 14 6 Y' 15 4 Y' yr 17 4 Y' LATE DEATH Undiagnosed TAPVD "Pump lung" "Pump lung" Pneumothorax; cardiac arrest; brain damage Thrombosis in peripheral pulmonary arteries Lung infection Acute residual VSD; low cardiac output Multiple VSDs; low cardiac output Thrombosis in peripheral pulmonary arteries Emergency operation; patient unconscious; no recovery after operation Residual VSD; low cardiac output Iatrogenic hyperpotassemia ; small pulmonary arteries 1 13 yr Subacute bacterial endocarditis TAPVD = total anomalous pulmonary venous drainage; VSD = ventricular septa1 defect. while he was on the ventilator. Subsequently, brain damage and cardiac arrest occurred. A 3-year-old child died of lung infection. Another patient, 6 years old, underwent emergency operation in a comatose state caused by severe cyanotic spells. There already was some brain damage before operation. Total repair was performed, but the child died postoperatively with irreversible brain damage. The single late death occurred 4 months after a 13- year-old patient had been discharged from the hospital and was due to subacute bacterial endocarditis. The VSD patch became detached, and the teenager died suddenly with pulmonary edema. Long-term Follow-up Long-term survivors were reviewed regularly in the outpatient clinic at Groote Schuur Hospital and Red Cross Hospital between January, 1974, and June, The minimum follow-up was 6 months and the longest, 8 years (mean duration, 4.25 years). Fifteen percent or 46 of the patients were from overseas. Long-term follow-up is available for only 5% of them. Patients from throughout South Africa who can- not attend the outpatient clinic in Cape Town are followed up in their respective regional hospitals. One hundred ninety-eight patients were asymptomatic and required no medication. They were regarded by their parents, doctors, or both as having an exercise tolerance appropriate to their age. Twenty-five patients had residual symptoms. The other 20 patients were lost to follow-up. Twenty-five patients underwent reexamination because of a suspected residual defect. In 17 of them, the outflow gradient was less than 35 mm Hg or the residual VSD was insignificant. The remaining 8 patients were the only ones in this series to undergo reoperation. Five with residual VSDs had another operation because of congestive cardiac failure or severe hemolysis. Three underwent reoperation for relief of major obstruction of the right ventricular outflow tract. Since routine postoperative catheterization has not been considered necessary, a few asymptomatic patients may have residual shunts or right ventricular hypertension and may require reoperation in the future. Nevertheless, since all reoperations were done within a few months of the first operation, it is unlikely that longer follow-up will increase the incidence of this event, except possibly in patients with a transannular patch. In such patients, the finding of increasing right ventricular enlargement suggests that some may ultimately require the insertion of a valve beneath the patch. Right bundle-branch block was present in 80% of the patients (241 patients) and left anterior hemiblock plus right bundle-branch block, in 9% (27 patients). Complete heart block was present in 2 patients who both required permanent pacemakers [ll, 18, 19, 21-24]. Comment In deciding whether a shunt should precede complete repair, we believe that age is not as important a consideration as the anatomy of the outflow tract of the right ventricle and pulmonary arteries, or the presence of abnormal coronary arteries. A poorly developed pulmonary artery system will not accommodate the total cardiac output resulting from closure of the VSD. In infants, our first choice is a Blalock-Taussig shunt or the modified shunt with a graft, usually Gore-Tex. We have abandoned the Waterston shunt in our practice. In older children, it is still unknown whether the shunt procedure or roofing the outflow tract (leaving the VSD open) is preferable to enlarge the pulmonary arteries. In total correction, the frequency with which a transannular patch is used to repair the right ventricular outflow tract varies considerably in different series. Our approach has been slightly aggressive to minimize the residual obstruction postoperatively and the number of early deaths due to low cardiac output. This inevitably results in a greater incidence of pulmonary regurgitation. However, the incidence of pulmonary regurgitation in early mortality is n$nimal compared with that caused by incomplete relief of the right ventricular obstruction. In the long run, there is evidence to suggest

5 435 Collective Review: Sdnchez et al: Tetralogy of Fallot Table 4. Early Deaths among 820 Patients with Tetralogy of Fallot Seen at Groote Schuur Hospital and Red Cross War Memorial Children s Hospital during a 23-Year Period No. of No. of Period Patients Deaths Percentage Adults (>20 years old) Total that postoperative pulmonary regurgitation in these patients is well tolerated except in the presence of other severe defects. Nevertheless, with the volume loading of the right ventricle in patients in whom a transannular patch is used, the right ventricular function remains a cause for concern. Aneurysms of the outflow tract are rare. They can be divided into either true or false aneurysms. The true aneurysms usually appear in the first 6 months after operation. The false aneurysms increase in size more quickly and have a higher incidence of rupture. In patients with cyanotic heart disease and low flows, for example, patients with tetralogy of Fallot, the typical focal thrombotic lesions of the pulmonary arteries, with possible fatal outcome, may be seen. These lesions could be related to the polycythemia and lowered velocities of flow, although involvement of a variety of coagulation factors cannot be excluded. Even with early repair at the age of 10 months and 5 years, 2 of our patients died of this pathological condition [l-4, 231. Hospital mortality was not higher in those patients having patch-graft enlargement across the pulmonary valve ring than in those undergoing other types of repair. After repair, hemodynamic abnormalities are minimal. The most common are mild right ventricular hypertension (30 to 45 mm Hg), a small gradient between the right ventricle and pulmonary artery (10 to 25 mm Hg), and pulmonary regurgitation. Minor electrophysiological changes are the rule after repair of tetralogy. Right bundle-branch block is found in 80 to 90% of patients after repair. Combined with left anterior hemiblock, it occurs much less frequently (7 to 10%). Sudden deaths may occasionally occur in patients with right bundle-branch block. Therefore, it is an indication of the need for a permanent pacemaker. In other series, no deaths were reported [22]. Intracardiac repair of tetralogy of Fallot can be performed in symptomatic children and adults-except for children with underdeveloped pulmonary arterieswith low operative risks and excellent late results in terms of hemodynamics. We believe that some compli- cations encountered in the present series can be prevented by using proper preoperative and intraoperative measurements as well as refined techniques of repair. We wish to thank the Chief Medical Superintendent of Groote Schuur Hospital, Dr. H. Reeve Sanders, and the Senior Medical Superintendent of Red Cross Memorial Children s Hospital, Dr. J. G. L. Strauss, for permission to publish. References 1. Barnard CN, Barnard M: The surgical correction of Fallot s tetralogy. Isr J Med Sci 11:116, Barnard CN, Schrire V: The surgical approach to tetralogy of Fallot. S Afr Med J 40:330, Barnard CN, Schrire V: The surgical treatment of the tetralogy of Fallot. Thorax 16346, Sdnchez HE, Barnard M, Barnard CN: Tratamiento quirurgico de la tetralogia de Fallot. Prensa Med Argent , Hamilton D, Di Eusanio G, Piccoli GP, Dickinson DF: Eight years experience with intracardiac repair of tetralogy of Fallot. Br Heart J 46:144, Lillehei CW, Cohen M, Warden HE, et al: Complete anatomical correction of the tetralogy of Fallot defect: report of a successful surgical case. Arch Surg 73:525, Kirklin JW, Ellis FH, McGoon DC, et al: Surgical treatment for the tetralogy of Fallot by open intracardiac repair. J Thorac Surg 3722, Pacifico A, Kirklin J, Blackstone E: Surgical management of pulmonary stenosis in tetralogy of Fallot. J Thorac Cardiovasc Surg 74382, Akasaka T, ltoh K, Ohkawa Y, et al: Surgical treatment of anomalous origin of the left coronary artery from the pulmonary artery associated with tetralogy of Fallot. Ann Thorac Surg 31:469, Hurwitz R, Smith W, King H, et al: Tetralogy of Fallot with abnormal coronary artery: 1967 to J Thorac Cardiovasc Surg 80:129, llbawi M, Idriss F, Muster A, et al: Tetralogy of Fallot with absent pulmonary valve. J Thorac Cardiovasc Surg 81:906, Tucker W, Turley K, Ullyot D, Ebert F: Management of symptomatic tetralogy of Fallot in the first year of life. J Thorac Cardiovasc Surg 78:494, Arciniegas E, Blackstone EH, Pacifico AD, Kirklin JW: Classic shunting operations as part of two-stage repair for tetralogy of Fallot. Ann Thorac Surg 27514, de Leval MR, McKay R, Jones J, et al: Modified Blalock- Taussig shunt. J Thorac Cardiovasc Surg 81:112, Donahoo JS, Gardner TJ, Zahka K, Kidd BSL: Systemicpulmonary shunts in neonates and infants using microporous expanded polytetrafluoroethylene: immediate and late results. Ann Thorac Surg 30146, McKay R, de Leval MR, Rees P, et al: Postoperative angiographic assessment of modified Blalock-Taussig shunts using expanded polytetrafluoroethylene (Gore-Tex). Ann Thorac Surg 30:137, Parenzan L, Alfieri 0, Vanini V, et al: Waterston anastomosis for initial palliation of tetralogy of Fallot. J Thorac Cardiovasc Surg 82:176, 1981

6 436 The Annals of Thoracic Surgery Vol 37 No 5 May Goor D, Smolinsky A, Mohr R, et al: The drop of residual right ventricular pressure after conservative infundibulectomy in repair of tetralogy of Fallot. J Thorac Cardiovasc Surg 81:897, Katz N, Blackstone E, Kirklin J, et al: Late survival and symptoms after repair of tetralogy of Fallot. Circulation 65403, Matsuda H, lhara K, Mori T, et al: Tetralogy of Fallot associ- Bted with aortic insufficiency. Ann Thorac Surg 29:529, Miller DC, Rossiter SJ, Stinson EB, et al: Late right heart reconstruction following repair of tetralogy of Fallot. Ann Thorac Surg 28939, Chesler E, Beck W, Schrire V Left anterior hemiblock and right bundle branch block before and after surgical repair of tetralogy of Fallot. Am Heart J M45, Hoffman JlE, Rudolf AM, Heyman MA: Pulmonary vascular disease with congenital heart lesions: pathologic features and causes. Circulation M873, Wessel H, Weiner M, Paul M, Bastanier C: Lung function in tetralogy of Fallot after intracardiac repair. J Thorac Cardiovasc Surg 82616, 1981