EXPERIMENTAL ASSESSMENT OF RIGHT-VENTRICULAR FUNCTION IN NORMAL PIGS WITH A LEFT-VENTRICULAR ASSIST DEVICE

Right ventricular (RV) failure during the use of a left ventricular as sist device (LVAD) is the leading cause of death in circulatory suppor t patients. Previous work, both experimentally and clinically, has sho wn the difficulties in predicting the behavior of the right ventricle at the start of LVAD. An experimental study has been designed to evalu ate RV functional changes during LVAD and its relation to preload chan ges. The model used adult mongrel pigs (n = 10). Right ventricular fun ctional parameters were measured with a thermodilution RV ejection fra ction catheter. The left ventricle was supported by a Nippon Zeon bloo d pump. Two groups were studied, the first one was the LVAD-off group (n = 5) and the other was the LVAD-on group (n = 5) which was supporte d by LVAD at maximum flow. Change of cardiac output, mean pulmonary ar tery pressure (PAP), RV stroke work, and RV ejection fraction in both groups were not significantly different. However, the relationship bet ween right ventricular end-diastolic pressure (RV-EDP) and right ventr icular stroke volume (RVSV) was significantly changed at a high level of RV-EDP. When RV-EDP was over 6.5 mm Hg in the LVAD-off group, RVSV decreased to 52.3 +/- 11.5 ml while in the LVAD-on group, RVSV increas ed to 97.2 +/- 22.0 ml. The change in PAP in the LVAD-on group was low er than in the LVAD-off group. We conclude that, at the volume overloa d state, LVAD can reduce the afterload of the right ventricle and main tain Frank-Starling's effect, thus having a beneficial effect on right ventricular performance.