Right ventricular function during left heart bypass.

Right heart failure may occur during mechanical support of the left ventricle (LV). Right ventricular (RV) functional changes were studied in eight dogs (26.9 +/- 1.4 kg) subjected to various degrees of left heart bypass (LHBP) with a roller pump. The venous return to the right atrium was controlled with a second pump. RV function was evaluated by peak RV developed pressure, its first derivative (dp/dt), and mean RA pressure measurements. Left atrial, LV, and aortic pressure and both roller pump flows were determined. Incremental increases in LHBP flow ratio ([LHBP flow x 100] divided by venous return flow) to 60%, 90%, and 100% were associated with decrements in RV dp/dt from the control of 212 +/- 17 torr/sec to 192 +/- 16, 178 +/- 16, and 168 +/- 13 torr/sec, respectively. Biventricular bypass or total cardiopulmonary bypass with extracorporeal membrane oxygenation seems to be indicated if LHBP flow ratio greater than 90% is required to maintain adequate body perfusion. Maximal LV decompression to obtain the greatest reduction of LV myocardial oxygen consumption may not be the ideal goal during LV mechanical assistance.