Novel techniques of mechanical circulatory support for the right heart and Fontan circulation

Currently available ventricular assist devices are designed primarily for use in patients with left sided heart failure. This study evaluated the efficacy of the Jarvik 2000 ventricular assist device (VAD) as a pulmonary pump to power a Fontan circuit in a large animal model.

Without the use of cardiopulmonary bypass, Fontan circulations were surgically created in 4 pigs (50 kg) using synthetic grafts from the inferior and superior vena cavas to the main pulmonary artery. Subsequently, the VAD was implanted within the common Fontan graft to provide a pulmonary pump. Direct chamber pressures and epicardial Doppler images were taken during the various phases of the experiment. Heart rate, femoral artery blood pressure, oxygen saturation, and aortic flow rate were continuously recorded. The outflow cannula of the VAD was then partially banded by 50% and then 75% to mimic increased afterload.

Fontan and VAD implantation was successfully performed in all 4 animals. Arterial pressure and aortic flow decreased dramatically with institution of the Fontan but were restored to baseline upon activation of the VAD. The pressure within the systemic venous circulation rose precipitously with institution of the Fontan circulation and improved appropriately with activation of the VAD. Adequate perfusion was maintained during increased afterload.

An axial flow VAD can restore normal hemodynamics and cardiac output when used as a pulmonary pump in a Fontan circulation. A VAD can rescue a failing Fontan as a bridge to transplant or recovery, even in the setting of high pulmonary resistance.