Comparison of a steady flow pump to a preload responsive pulsatile pump in left atrial-to-aorta bypass in canines.

: A unique preload responsive pulsatile pump was compared to a centrifugal pump in total cardiac support in 25–kg canines (n = 6, each group) in the left atrialto–aorta mode during 5 h of ventricular fibrillation. With steady flow, there was immediate drop in output from 2.1 ± 1.0 L/min to 1.4 ± 0.3 L/min, followed by further reduction to 0.9 ± 0.2 L/min during 5 h of ventricular fibrillation. With a pulsatile pump, there was no significant reduction from control of 2.4 ± 0.6 L/min and no decline during 5 h of ventricular fibrillation. With steady flow, systemic vascular resistance (SVR) rose significantly from 1,762 dyne–s–cm-5 immediately on pump to 3,013 dyne–s–cm- at 5 h. With physiologic pulsatile flow, significant elevation of SVR did not occur. When stressed, due to diminished left atrial return, the centrifugal pump displayed line chatter and streaks of microbubbles, whereas the pulsatile pump did not. Crystalloid volume replacement with the centrifugal pump was 6.5 ± 1.9 L, and with the preload responsive pulsatile pump, 5.6 ± 1.3 L. It is concluded that in the left atrial–to–aorta mode during 5 h of ventricular fibrillation and with comparable volume replacement, total cardiac support of canines is associated with lower SVR with physiologic pulsatile flow and is not accompanied by line chatter and cavitation with this preload responsive pump.