Augmentation of pulmonary blood flow by a right atrial balloon pump after the Fontan operation

The Fontan principle of right ventricular exclusion is frequently applied to complex congenital lesions. Results are adversely affected by increases in pulmonary vascular resistance and/or ventricular end-diastolic pressure. Survival depends on means to increase pulmonary blood flow. To address this problem, we have developed a triple-balloon catheter that is passed via the femoral vein to the right atrium. Inflation is sequenced so that small balloons located at the junction of each vena cava with the atrium inflate first. Then the larger central balloon inflates, ejecting blood from the right atrium to the pulmonary arteries. The pump is timed to inflate during ventricular systole. In this study, we tested the catheter in vivo in eight dogs. Tricuspid atresia was created and right ventricular exclusion accomplished. Pulmonary blood flow was measured with a flow probe in the right atrium-to-pulmonary artery conduit, at central venous pressures of 15, 20, and 25 mm Hg. Pulmonary blood flow was increased by balloon pumping in every instance (p < .05). Maximal augmentation of pulmonary blood flow (25.5%) was achieved at a central venous pressure of 15 mm Hg with a balloon ratio of 1:2. Less augmentation was achieved at a central venous pressures of 20 mm Hg (8.4% to 13.0%) and a 25 mm Hg (4.4% to 5.3%) and at balloon ratios of 1:4 and 1:8. We conclude that (1) a triple-balloon pump in the right atrium can significantly augment pulmonary blood flow after right ventricular exclusion and (2) most effective augmentation can be achieved without excessive volume loading. Pulsatile augmentation of pulmonary blood flow with this device should improve survival after Fontan operations.