Is Four Stage Management the Future of Univentricular Hearts? Destination Therapy in the Young

For the child born with a functionally univentricular heart, multi-stage surgical palliation culminating in the Fontan operation is now well established as the standard of care. Though this is an effective approach, there are several inherent disadvantages to the Fontan circulation: subnormal resting cardiac output, impaired exercise capacity, increased risk of thromboembolism, and increased risk of arrhythmia. Perhaps most importantly, the long-term deleterious effects of substantial systemic venous hypertension, which is necessary to "drive" blood through the pulmonary vascular bed, include progressive dysfunction of other organ systems, particularly renal, lymphatic, gastrointestinal, and hepatic systems. When such dysfunction is advanced, heart transplantation or even heart-liver transplantation may be a reasonable option. However, because the syndrome seems to be increasingly widespread and there is already a significant donor shortage, alternative solutions are required. Because many patients with "failing Fontan" physiology have preserved systemic ventricular function, application of a systemic ventricular assist device is unlikely to be effective. However, for such patients, a right-sided sub-pulmonary ventricular assist device is an intellectually appealing solution. Several such devices have been proposed or are in varying stages of evaluation. The lack of economic incentive for development of right-sided pumps may be partially ameliorated both by recognition of the size of the cohort of Fontan patients now surviving into adulthood as well as by the increasing recognition of important right-sided heart failure in adults with biventricular hearts supported only with durable left-sided ventricular assist devices.