Growth of oversized grafts in neonatal heart transplantation

Background. Because of the severe shortage of neonatal organ donors, oversized cardiac allografts are frequently transplanted. This study examined body and graft growth of neonates who receive an oversized heart. Methods. We studied 51 neonates, who received transplants between November 1986 and August 1992m, for changes in body weight, left ventricular mass, and enddiostolic volume measured at 1 week, 1, 3, and 6 months, and yearly after cardiac transplantation. Patients were divided into two groups according to donor/recipient weight ratios: the normal group, where the donor/recipient weight ratio was 1.5 or less (1.06 ± 0.05; n = 24), and the oversized group, where the donor/recipient weight ratio was more than 1.5 (2.22 ± 0.10; n = 27). Results. After cardiac transplantation, body weight increased continuously in both groups with no difference between groups. In the oversized group, left ventricular end-diastolic volume at 1 week and left ventricular mass at 1 week and 1 month were significantly higher than those in the normal group (p < 0.01). In the normal group, end-diastolic volume and left ventricular mass increased continuously. In the oversized group, however, left ventricular mass significantly decreased until 3 months after cardiac transplantation and then increased continuously, whereas end-diastolic volume increased continuously throughout the posttransplantation period. Conclusions. These data suggest that oversized cardiac allografts shrink at first and then grow as the recipient grows. There appears to be a size adaptation of the large cardiac allograft to accommodate to the reduced requirements of the neonate.