Beneficial Effect of a Balanced Biventricular Bypass System on Left Ventricular Energetics

We developed a biventricular bypass (BVB) system for the treatment of postcardiotomy ventricular failure. This study investigated the effect of BVB on left ventricular (LV) performance in comparison with venoarterial bypass (VAB) using the LV pressure-volume relationship. Eight adult mongrel dogs (14～21 kg) underwent VAB with right atrial and femoral arterial cannulation. Left atrial cannulation was added for BVB, and both atrial drainage tubes were joined with a Y-shaped connector. Bypass flow was maintained at half of the baseline cardiac output. A high-fidelity micro-tip catheter and a conductance catheter were used to evaluate LV function. The slope of the LV end-systolic pressure-volume relation (Emax), LV stroke work (SW), LV potential energy (PE), LV pressurevolume area (PVA), the slope of the SW-end-diastolic volume relation (preload recruitable stroke work : PRSW), and the PE/PVA ratio (an index of the LV energy economy) were assessed. Emax showed no significant changes during each experiment. PRSW was reduced by BVB compared with the baseline and with VAB. The PE/PVA ratio only increased significantly during BVB. These results suggested that BVB might provide an effective circulatory support for reducing LV work and improving the LV energy efficiency