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 assist device (LVAD) is the leading cause of death in circulatory support patients. Previous work, both experimentally and clinically, has shown the difficulties in predicting the behavior of the right ventricle at the start of LVAD. An experimental study has been designed to evaluate RV functional changes during LVAD and its relation to preload changes. The model used adult mongrel pigs (n = 10). Right ventricular functional parameters were measured with a thermodilution RV ejection fraction catheter. The left ventricle was supported by a Nippon Zeon blood 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 supported by LVAD at maximum flow. Change of cardiac output, mean pulmonary artery pressure (PAP), RV stroke work, and RV ejection fraction in both groups were not significantly different. However, the relationship between right ventricular end-diastolic pressure (RV-EDP) and right ventricular 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 increased to 97.2 +/- 22.0 ml. The change in PAP in the LVAD-on group was lower than in the LVAD-off group. We conclude that, at the volume overload state, LVAD can reduce the afterload of the right ventricle and maintain Frank-Starling's effect, thus having a beneficial effect on right ventricular performance.