Cavopulmonary assist: circulatory support for the univentricular Fontan circulation

Following Fontan palliation, the univentricular circulation is notable for coexisting systemic venous hypertension and pulmonary arterial hypotension. Assisted cavopulmonary blood flow to overcome this pressure gradient would restore the circulation to one more closely resembling normal two-ventricle physiology. We hypothesized that mechanical augmentation of cavopulmonary blood flow would provide physiologic stability in a model of cavopulmonary diversion and univentricular circulation.

Yearling sheep (n = 13, mean weight 56.5 kg) underwent total cavopulmonary diversion on cardiopulmonary bypass. The superior and inferior vena cavae were anastomosed directly to the right pulmonary artery. Axial flow pumps were positioned within both vena cavae to assist blood flow from the systemic venous circulation into the pulmonary vasculature. Baseline ventilation was resumed, cardiopulmonary bypass was weaned, and pump support was titrated to obtain normal physiologic measurement. Cardiopulmonary data were collected for 6 hours.

All animals demonstrated hemodynamic stability without need for volume loading, inotropic support, or pulmonary vasodilator therapy. Cardiac output, pulmonary vascular resistance, pulmonary arterial pressure, inferior vena caval pressure, and arterial pCO(2) and pO(2) values 6 hours after intervention were similar to baseline values. Arterial lactate levels steadily decreased throughout the cavopulmonary assist period.

Cavopulmonary assist with a percutaneous pump provides physiologic stability in a model of total cavopulmonary diversion and univentricular Fontan circulation without altering regional volume distribution or cardiac output. This mode of circulatory support may have potential to benefit patients with marginal Fontan hemodynamics in both the early and late time periods.