Infant and donor organ growth after heart transplantation in neonates with hypoplastic left heart syndrome

Background: There is little published data regarding somatic growth and changes in allograft size after heart transplantation in infants with hypoplastic left heart syndrome. Methods: We evaluated the somatic growth of 26 infants with hypoplastic left heart syndrome who underwent heart transplantation over a 5-year period and measured changes in left ventricular dimensions in 22 of those infants. Age at transplantation was 27 ± 17 days (mean ± standard deviation), and the follow-up period was 43 ± 14 months. Growth and echocardiographic data were converted to standard deviation (Z) scores for comparison with normal populations. Results: Height and weight were always within normal limits (two standard deviations), with a trend toward smaller size throughout the follow-up period. The somatic growth of infants on low-dose maintenance steroids was not significantly different from that of infants withdrawn from chronic steroid regimens. Initial left ventricular posterior wall and septal dimensions were greater than two standard deviations (+4.3 and +6, respectively), probably the result of routine use of oversized donors, but the dimensions decreased to within the normal range during the first year. They then remained within normal limits during follow-up. With one exception at 2 years after transplantation, left ventricular diastolic dimensions were always within two standard deviations of the mean. Left ventricular dimensions of patients with hypertension, rejection, or acute graft failure were not significantly different from patients without these complications. Conclusions: Neonates with hypoplastic left heart syndrome who undergo heart transplantation can be expected to have somatic growth within normal limits. However, the trend toward growth retardation is worrisome. Left ventricular wall dimensions adjust to smaller recipient size during the first year after transplantation and then remain appropriate for the recipient's size over time.