Tetralogy of Fallot with subarterial ventricular septal defect. Diagnostic and surgical considerations.

Since 1964, 77 patients underwent repair for tetralogy of Fallot with subarterial ventricular septal defect. Median age at operation was 5 years. Cyanosis was commonly mild, and hypoxic episodes were infrequent. Accordingly, only 12 patients (15.58%) needed either palliative or corrective operations before the age of 2 years. Characteristic angiographic and echocardiographic features were observed, which allowed this entity to be differentiated from either classic tetralogy or other types of double-outlet right ventricle. The earliest series of operations (in which no right ventricular outflow patch was used) was followed by a prohibitive mortality (50%). Residual subpulmonary obstruction was the cause of all of these deaths. In a second series of patients, a transannular patch was frequently used (79.59%), with the rationale that closure of the ventricular septal defect would make restrictive the deficient infundibulum of these patients. In a later series, we observed that most of the patients had a nonrestrictive pulmonary anulus (80%); the patch therefore was limited to the ventriculotomy. In the absence of pulmonary annular hypoplasia, the need for patching of the right ventricular outflow tract in this entity has to be confined to preventing the subpulmonary obstruction induced by closure of the ventricular septal defect. A considerable improvement in the results followed our first series (4.3% mortality). Follow-up of the survivors (mean 7 years) has been satisfactory.

Tetralogy of Fallot with subpulmonary ventricular septal defect.

Among a total of 608 patients with tetralogy of Fallot, 35 with tetralogy and subpulmonary ventricular septal defect (VSD) have undergone intracardiac repair at the Children's Hospital, Buenos Aires. The crista supraventricular was absent in 62.9% of these patients; it was hypoplastic in 37.1%. Only 3 patients (8.6%) were severely cyanotic and required operation in infancy. The main and left and right pulmonary arteries were relatively large in all but 1 patient. Nevertheless, patch-graft enlargement across the pulmonary valve ring was necessary in 20 (57.1%). We believe that closure of the subpulmonary VSD increase the apparent severity of the pulmonary stenosis and necessitates patch-graft enlargement in patients in whom the appearance of the right ventricular outflow tract before repair would not have suggested its need.