ABSTRACT

Mechanical circulatory support using ventricular assist devices (VADs) has been shown to benefit many patients in whom the pumping function of the heart is inadequate. Mechanical VADs restore tissue perfusion by supporting the circulation and allow the failing myocardium to rest by decreasing preload and thereby reducing end-diastolic and end-systolic ventricular size. It has become a standard option of circulatory support in adult patients with cardiac failure refractory to pharmacological therapy. A variety of devices have been successfully used clinically as a bridge to recovery of ventricular function or cardiac transplantation with acceptable morbidity and mortality (1-5). Aggressive extracorporeal circulatory support has been increasingly applied in infants with severe cardiopulmonary dysfunction in the hope that survival can be improved even in pediatric patients with complex congenital cardiac anomalies undergoing extensive surgical repair. While the indications and outcome of pediatric patients requiring circulatory support are preliminary and still evolving, the clinical experience at the Children's Hospital in Boston is encouraging and favorable (6). However, fewer treatment options for mechanical circulatory support are available for infants and small children who experience profound ventricular dysfunction. At the present time, extracorporeal membrane oxygenation (ECMO) is the support method of choice in the pediatric cardiac patients if there is severe

pulmonary dysfunction either preoperatively or postoperatively. In small neonates «5 kg) with isolated biventricular failure, ECMO also facilitates cannulation. On the other hand, regardless of patient size, when single-ventricle dysfunction is present or isolated biventricular failure without pulmonary dysfunction in larger-size infants exists, VAD is preferable. The isolated VAD simplifies the ECMO circuit and offers an advantage in that it reduces blood cell trauma, hemorrhagic complications, and capillary leak that attend total cardiopulmonary bypass (CPB) and ECMO. The development of a pulsatile VAD for children, however, has been limited by size constraints and the requirement of multiple pumps with different volumes to accommodate a wide range of pediatric sizes. At present, there is no pulsatile VAD available in United States for pediatric patients.