Pediatric cardiac transplantation is an established treatment option for children with hypoplastic left heart syndrome, other complex congenital anomalies not amenable to surgical treatment, and various forms of end-stage cardiomyopathy.
The International Society for Heart and Lung Transplant recorded over 3000 pediatric cardiac transplants. In contrast to earlier years, congenital heart disease has emerged as the most common diagnosis leading to transplantation, accounting for 50–60% of transplants. Moreover, 20–30% of pediatric cardiac transplants occur in infants. Although similar in several respects to adult cardiac transplantation, there are important differences. The significant number of children with congenital anomalies imposes unique demands on explantation (usually several previous surgeries) and thoughtful preservation of certain structures needed for ultimate reconstruction with the transplanted heart. There is also a greater range of donor-recipient size mismatch and longer ischemic times associated with pediatric cardiac transplantation. Postoperative surveillance may differ as well, particularly in infants, for whom routine transvenous endomyocardial biopsy or intravenous ultrasound may be used less frequently. At its current state of development, ABO-incompatible transplantation is an opportunity uniquely available for infants. This requires use of appropriate type blood products, plasma exchange, and confirmation of absence of antibodies to blood products before reperfusion of the donor heart. Thus far, results appear to be comparable to those in ABO-compatibly transplanted infants.
The decision to transplant occurs in the context of multidisciplinary counseling and consultation and is a decision that obviously cannot be taken lightly by the family or the team. Once a patient is identified as a potential candidate, established protocols guide a thorough evaluation of ultimate suitability for transplantation. Careful analysis of native and palliated or reconstructed anatomy is imperative for successful conduct of the operation.
Immunosuppression is similar to that used in adults and is usually some form of triple therapy consisting of cyclosporine, azathioprine, and corticosteroids. Induction therapy with antithymocyte globulin, monoclonal antibodies may be considered. Prompt steroid withdrawal or a steroid-free regimen is a recognized practice in children, motivated by the deleterious effects of corticosteroids, particularly growth impairment.
Posttransplantation issues for the child are similar to those for the adult. Bleeding, graft dysfunction, rejection, posttransplant lymphoproliferative disease, and graft vasculopathy are all recognized issues. Transplant coronary artery disease has been a particularly vexing issue that has generated competing explanatory theories. One theory considers vasculopathy a consequence of inadequate immunosuppression and rejection and recommends more intense immunosuppression. At the other extreme is the theory that corticosteroids in some way promote vasculopathy, so that reduced dosage or withdrawal of steroids is recommended. Transplant coronary artery disease occurs in 10% of patients, is difficult if not impossible to treat effectively, and typically prompts consideration for retransplantation. Rejection is a common event, occurring with an incidence of approximately 0.5 episodes per patient year, and continues to contribute to mortality. Because of concern for rejection and transplant coronary artery disease, routine surveillance is common practice, using a combination of echocardiography, transvenous endomyocardial biopsy, and intravascular ultrasound. Infection occurs in over 50% of recipients and is another recognized contribution to mortality.
Five-year survival ranges between 60% and 75%. Recent results indicate similar survivals between patients with congenital anomalies, other forms of cardiac disease. Mortality is somewhat higher for infants and may be due to a higher incidence of early graft dysfunction. Outcome analyses do not always include pretransplant mortality. The decision to transplant necessarily invokes a period of waiting for a suitable donor, a period with a mortality that approximates 20%. This is a significant figure that should be acknowledged in the process of choosing between transplantation and another available therapeutic option.