Between January 1987 and May 1990, six children underwent ventricular assisted circulation for recovery of myocardial function after cardiac surgery. Their ages ranged from 9 months to 12 years. Three patients had tetralogy of Fallot and one had atrioventricular discordance with ventriculoarterial concordance, ventricular septal defect, and under-over ventricles. Double outlet left ventricle and a large ventricular septal defect with pulmonary hypertension was present in the remaining two. The duration of circulatory support averaged 126 +/- 57 h. An extracorporeal membrane oxygenator (ECMO) was used in four patients, biventricular assistance with centrifugal pumps in one, and left ventricular assistance followed by ECMO in the last patient. Circulatory support was begun in the operating room in two patients who could not be weaned from cardiopulmonary bypass. Both these patients are long-term survivors. Assisted circulation was implanted in four patients in the intensive care unit because of low cardiac output refractory to any pharmacological treatment. Only one of these patients could be weaned from circulatory support but he died 20 days later because of multiorgan failure due to persistent poor myocardial function. The causes of death in the remaining three patients were intracranial hemorrhage, untreatable bleeding, and failure of myocardial recovery, respectively. We believe that early postoperative use of circulatory support can be a major determinant for recovery of myocardial function in patients who have severe low cardiac output following repair of congenital cardiac lesions. Our initial experience with the use of biventricular assistance in small children is encouraging. Nevertheless, further observations are clearly necessary to establish the role of postoperative circulatory support in children with congenital cardiac lesions.