The surgery of congenital heart disease began with palliative procedures designed to reduce the effects of the cardiac anomaly without attempting to correct the abnormal anatomy or physiology. Examples of these procedures are the Blalock-Taussig shunt1 described in 1944 for lesions such as tetralogy of Fallot with inadequate pulmonary blood flow, and banding of the pulmonary artery2 for lesions with excessive pulmonary flow such as ventricular septal defect (VSD).
With the development of the heart lung machine3 in 1953 efforts were directed at complete correction. Certain complex lesions were palliated first, to be followed by a corrective procedure when a certain age or size had been reached. With the development of the technique of deep hypothermia and cardiac arrest smaller infants became candidates for direct repair with improved results.4
For many years complex lesions such as pulmonary atresia and tricuspid atresia could be palliated but not corrected. In 1965 Rastelli et als reported the establishment of continuity between the right ventricle and the pulmonary artery using an external conduit of pericardium with a valve. In 1966 Ross and Somerville6 described the repair of pulmonary atresia using a valve containing aortic homograft. Long-term followup revealed late calcifications of the homograft, frequently resulting in stenosis and requiring reoperation. In 1973' use of a dacron conduit containing a glu ta raid ehy de preserved porcine valve was described and became commercially available.
The valve containing conduit has made it possible to reestablish continuity between the right ventricle and the pulmonary arteries in cases of pulmonary atresia.6 Truncus art e nos us may also be treated using a similar technique8 after disconnecting the pulmonary arteries from the truncus and closing the VSD. In addition, the complex of , transposition of the great arteries with ventricular septat defect (VSD) and pulmonary stenosis can be repaired by redirecting the stream of blood from the left ventricle across the VSD and out the aorta beneath the VSD patch, while the conduit establishes continuity between the right ventricle and the disconnected pulmonary artery.9 Repair of tetralogy of Fallot in certain situations also requires use of a valved conduit or porcine valve in the pulmonary position.16 Another advance came with the use of the valved conduit to reestablish continuity between the right atrium and the pulmonary artery or right ventricle in cases of tricuspid atresia - the so called Fontan procedure10 which has also been applied to other complex lesions."
MANAGEMENT OF CARDIOPULMONARY BYPASS
A membrane oxygenator is used for cardiopulmonary bypass (CPB) with moderate hemodilution (hematocrit 25% to 30%) and systemic hypothermia varying from a tympanic membrane temperature of 2O0C to 280C. In most cases a median sternotomy is used. Where a previously placed valved conduit is present, or in tricuspid atresia, with a previous median sternotomy, because of adherence of the conduit or right atrium to the sternum, a transverse bilateral thoracotomy is used, especially when the right chest had not previously been entered. In order to establish CPB, the ascending aorta is usually cannulated and the superior and inferior vena cava are cannulated via the right atrium. Where a previous superior vena cava to right pulmonary artery (Glenn) shunt has been performed, the superior vena cava is cannulated directly. A previous Waterston shunt (ascending aorta to right pulmonary artery shunt) generally results in kinking of the right pulmonary artery requiring reconstruction, either with a pericardial patch or insertion of a graft from the conduit to the pulmonary artery. A previously placed Glenn shunt may be taken down, using polytetrafluorethylene grafts to reestablish continuity between the superior vena cava and the right atrium and between the main pulmonary artery and the right pulmonary artery (Figure 6). The ventricular septal defect is closed with a double velour dacron patch and continuous sutures of prolene. Myocardial protection is provided by the administration of cold blood cardioplegia (IO ml/ kg) containing 30 mEq KCl/ L every 20 to 30 minutes during cross-clamping.
Figure 1. This 11-year-old patient had pulmonary atresia with a ventricular septal defect (VSD). The pulmonary arteries are supplied by a patent ductus arteriosas (left). The right upper lobe is supplied by a large vessel arising from the descending aorta. The repair shown on the right consisted of !igating the ductus, closing the VSD through an incision in the right ventricle, and placing a 25 mm porcine valved conduit between the right ventricle and pulmonary artery. The artery to the upper right iobe was banded until the distal pressure was 18 mm Hg. (Reprinted with permission from Laks H, et al.'5)
Figure 2. An eight-year-old girl with pulmonary atresia and ventricular septal defect (VSD). As shown on the left, a Waterston shunt performed when the patient was a neonate resulted in obstruction of the right pulmonary artery on the medial side. Repair shown on the right consisted of closure of the VSD, placement of a 25 mm conduit between the right ventricle and the right pulmonary artery, and placement of a 10 mm Goretex graft from the conduit to the left pulmonary artery. (Reprinted with permission from Laks H, et al.'5)
Patients with these lesions may be grouped into those with a ventricular septal defect and those without.
Pulmonary Atresia with VSD
Children with this lesion are usually palliated up to the age of about four years or more by systemic to pulmonary artery shunts. When they develop increasing cyanosis and poly cy t he mia, complete repair is undertaken. This consists of takedown of the previous shunts, ligation or banding of bronchial collaterals arising from the aorta supplying the lungs, closure of the VSD with a dacron patch, and insertion of a valved conduit between the right ventricle and the pulmonary artery (as shown in Figures 1 and 2). The mortality of such a procedure is between 5% and 10%. Pulmonary atresia may exist with other complex lesions as shown in Figure 3.
Pulmonary Atresia without VSD
Neonates with these lesions usually require palliation within days of birth as the ductus begins to close. This usually includes a systemic to pulmonary artery shunt combined with a pulmonary valvotomy. If the tricuspid valve and right ventricle are adequate in size, subsequent repair entails closure of the atrial septal defect and complete relief of the RV outflow tract obstruction with or without insertion of a pulmonary valve. If the RV and tricuspid valve are inadequate in size, a modified Fontan procedure may be performed as shown in Figure 9.
Prior to the advent of early complete correction12 this lesion had a high mortality in the range of 50% to 70%. It is now recognized that repair is best undertaken within the first six months prior to the onset of pulmonary vascular disease or uncontrollable failure. The repair is described in Figure 4. In small infants a 12 mm conduit is usually used requiring reOperation at three or four years of age because of growth of the child and calcine deterioration of the porcine valve.
TRANSPOSITION OF THE GREAT VESSELS WITH VSD AND PULMONARY STENOSIS
Early attempts at correcting this complex of lesions consisted of an intra-atrial baffle repair and closure of the VSD. Usually, however, the left ventricular outflow obstruction could not be relieved and the results were poor. The Rastelli procedure corrects the lesion at the ventricular level as showing in Figure 5. The risk of this procedure is about 10%.
TETRALOGY OF FALLOT
In the vast majority of cases, a valved conduit is not required in the repair of tetralogy of Fallot. It may be indicated in cases with virtual atresia of the outflow tract, with single pulmonary artery, with elevated pulmonary artery pressure, where an anomalous left anterior descending coronary artery crosses the RV outflow tract and in some redo operations for tetralogy of Fallot.
We have now modified our technique in those patients in whom a valve is indicated, including absent pulmonary valve syndrome, but excluding patients with an anomalous coronary artery crossing the RV outflow tract.16 This method is shown in Figure 6. It consists of placing a porcine valve in the RV outflow tract beneath a transannular outflow patch rather than using the conduit. This allows insertion of a larger valve without the risk of the conduit kinking, or being compressed under the sternum.
THE FONTAN PROCEDURE
This operation, first described in 1 97 1 ll for the repair of tricuspid atresia, is based on the principle that an anatomically normal right ventricle is not required to adequately perfuse the lungs provided that the pulmonary vascular resistance is normal and that left ventricular function is unimpaired.
The procedure originally comprised a Glenn shunt (superior vena cava to right PA) and a valve in the inferior vena cava and in the conduit connecting right atrium (RA) and pulmonary artery.
The procedure has now been modified so that a Glenn shunt is no longer considered necessary. In addition, a valve is no longer placed in the inferior vena cava. Where a small RV chamber and a normal pulmonary valve is present the connection can be made between RA and RV with or without a valve. Where there is no RV chamber, a direct connection between RA and PA is made without a valve.
In addition to tricuspid atresia, the Fo man operation is also applied to other lesions such as single ventricle, pulmonary atresia and other complex anomalies."
With proper selection of patients the results of the Fontan procedure have been excellent with a mortality of about 10% and good long-term functions.
LONG-TERM FUNCTION OF THE PORCINE VALVE
The porcine valve in children has an increased propensity for calcifications and late obstruction. Approximately 20% will require replacement within five years. u Reoperations for replacing the conduit have been performed with an acceptable risk and the advantages in terms of hemodynamics and long-term cardiac function so far seem to outweigh the risk of reoperation.
Figure 3. This 11-year-old boy had dextrocardia, situs solitus, LLoop, and pulmonary atresia with the aorta arising from the right ventricle. As shown on the left, there were anomalies of systemic venous drainage, with azygous continuity of the inferior vena cava, a left superior vena cava, and a large hepatic vein draining into the "left atrium." A pericardia! baffle was used to separate the pulmonary and systemic venous drainage, and the left superior vena cava was I igated. A targe ventricular septal defect of the endocardia! cushion type was closed and a 25 mm porcine valve conduit was placed between the apex of the left ventricle, which was the pulmonary ventricle and the pulmonary artery. The previously placed right and left Blalock-Taussig shunts were ligated. (Reprinted with permission from Laks H, et al.15)
CLINICAL EXPERIENCE WITH COMPLEX REPAIRS REQUIRING THE PORCINE VALVE
We have had experience with 56 patients undergoing these complex repairs. Eight underwent repair of pulmonary atresia, seven repair of truncus arteriosus, eight repair of transposition with VSD and pulmonary stenosis, 13 repair of tetralogy of Fallot, and 20 underwent the Fontan procedure. There were four early deaths (less than 30 days) among these 56 patients.
The field of congenital heart surgery has advanced dramatically over the last ten years. Ingenious new procedures have been developed, which afford for the first time a physiologic correction for complex lesions which previously could only be palliated.
The concentration of these complex cases in specialized referral centers has made possible the development of specialized teams of surgeons, pediatrie cardiologists, neonatologists, and nurses. This development has advanced the sophistication of, and intensity of postoperative care. Advances in the techniques of surgery, the methods of myocardial protection and the conduct of cardiopulmonary bypass have improved the results, particularly in the infant group.
Figure 4. Repair of truncus arteriosus. Left, The pulmonary artery is disconnected from the truncus with primary closure of the aorta. Center, The conduit is anastomosed to the pulmonary artery and an incision made in the right ventricle through which the ventricular septal defect is closed. The proximal end of the conduit is then anastomosed to the edges of the right ventricular incision. (Reprinted with permission from Laks H, et al.")
Figure 5. Repair of transposition of the great arteries, ventricular septal defect (VSD), and pulmonary stenosis. Left, Dotted lines indicate incisions for dividing the main pulmonary artery (PA) and exposing the VSD through the right ventricle. Center, The oversewn stump of the proximal PA, the conduit sutured to the distal PA, and the VSD closed in such a way that the left ventricle is connected to the aorta. Right, The proximal end of the conduit is then sutured to the right ventricle. (Reprinted with permission from Laks H, et al.'5)
Figure 6. A 16-year-old girl with tetralogy of Fallot and virtual at res ia of the right ventricular outflow tract previously underwent a Glenn (superior vena cava to right pulmonary artery) shunt and a left Blalock-Taussig shunt. The dotted lines in the lefthand diagram indicate the atrial and ventricular septal defects, The Glenn shunt was taken down (right) using 12 mm Goretex grafts to reestablish continuity of the superior vena cava and right pulmonary artery. The right ventricular outflow tract was reconstructed using a Teflon patch with a 27 mm porcine valve implanted beneath it. (Reprinted with permission from Laks H, et al.15)
1. Blalock A: Surgical procedures employed and anatomical variations encountered in the treatment of congenital pulmonic stenosis. Surg Gvnecol Ohsiei 1 948; 87:385.
2. Stewart S. Harris P, Mannin J; Pulmonary Artery Banding. J Thorac Cardiovasc Surg 1980; 80:431-436.
3. Utley JR (cd): Pathophysiology and Techniques of Cardiopulmonary Bypass. Baltimore, Williams and Wilkins Co. 1982.
4. Barrati- B oyes BC. Simpson M, Neutze JM: lntracardiac surgery in neonate and infants using deep hypothermia with surface cooling and limited cardiopulmonary bypass. Circulation 1971; 43-44 (suppl I): 1-25.
5. Rastelli GC, Ongley PA, David GD. et al: Surgical repair Tor pulmonary valve at rcsia with coronary artery fistula: Report of a case. Mavo Clin PTOC 1965; 40:521-527.
6. Ross DN, Sommrville J: Correction of pulmonary a t resi a with a homograft aortic valve. Lancet 1966; 2:1446-1447.
7. Bowman FO. Hancock WD, Malm JR: A valve-containing dacron prosthesis. Arch Surg 1973; 107:724-728.
8. McGoon DC, Rastell GC, and Ongley PA: An operation for the correction of truncus arteriosus. JAMA 1968; 250:69.
9. Rastelli GC: A new approach to "anatomic" repair of transposition of the great arteries. Mayo Clin Proc 1969; 44:1-12.
10. Fontan F, Baudet E. Surgical repair of lricuspid atresia. Thorax 1971; 26:240-248.
11. Gale AW. Danielson GK, McGoon PC, et al: Modified Fontan operation for univentricular heart and complicated congenital lesions. J Thorac Cardiovasc Surg 1979; 78:831-838.
12. E ber t PA, Robinson SF, Stanger P. et al: Pulmonary artery conduits in infants younger than six months of age. J Thorac Cardiovasc Surg 1976; 72:351-356.
13. Laks H. Williams WG, Hellenbrand WE. et al: Results of right atrial to right ventricular and right atrial to pulmonary artery conduits for complex congenital heart disease. Ann Surg 1980: 192:382-389.
14. G ha AS, Laks H, Stansel HC, et al: Late failure of porcine valve heterografts in children. J Thorac Cardiovasc Surg 1979; 78:351-364.
15. Laks H, Hellen brand WE, Stansel HC: Repair of complex congenital cardiac defects with the valved conduit. Surg Clin Norih Am 1980; 60: 12251237.
16. Laks H, Hellenbrand WE, K lei n ma n CS, et al: Patch reconstruction of the right ventricular outflow tract with pulmonary valve insertion. Cardiovasc Surgery 1981; 64(suppl II):154-I6I.