Atrial, ventricular, or both cannulation sites to optimize left ventricular assistance?

The efficiency of left ventricular assist devices (LVADs) depends on the ca pacity of the inflow cannula to drain blood into the pump. Left atrial (LA) and left ventricular (LV) sites were compared in an animal model mimicking different hemodynamic conditions. Three calves (56.3 +/- 5.0 kg) were equi pped with a Thoratec LVAD. A regular cardiopulmonary bypass (CPB) circuit w as used as a right ventricular assist device (RVAD) (jugular vein/pulmonary artery), and preload conditions were adjusted by storage (or perfusion) of blood into (or from) the venous reservoir. LA and LV drainage, tested sepa rately or simultaneously, was measured by its effect on the LVAD's performa nce. The LVAD was used alone on a beating heart or together with the RVAD ( biVAD) on a beating and on a fibrillating heart. Increasing the central ven ous pressure (CVP) highlighted the differences between the LA and LV cannul ation sites when the LVAD was tested either alone or together with the RVAD (biVAD) on a beating heart. Drainage through the LA or the LV was similar when CVP was set at 8 mm Hg, and increasing CVP to 14 mm Hg allowed for bet ter drainage through the LV cannula. In contrast, after induction of fibril lation to mimic extreme heart failure, the drainage was better through the LA cannula. Using both LA and LV cannulae simultaneously did not improve th e LVAD output in any of the conditions tested. LV cannulation provides bett er blood drainage when used on a normal beating heart and, therefore, allow s for increased LVAD performance. However, in severe heart failure, blood d rainage through the LV cannula decreases and the LA cannulation site is sup erior.