Efficacy and mechanisms of biventricular and left/right direct cardiac compression in acute heart failure sheep.

Direct cardiac compression (DCC) with implanted heart patches has previously demonstrated efficacy of biventricular (BiV) support in acute heart failure (HF) sheep. We hypothesized that this was primarily due to a left ventricular (LV) effect. This study compared BiV, LV, and right ventricular (RV) assists in terms of hemodynamic and energetic response. Ten sheep underwent instrumentation and device implantation at least 1 week prior to study. HF (50% reduction in cardiac output) was maintained with intravenous esmolol infusion. BiV, LV, and RV assists were activated randomly with intervening stable HF periods. BiV assist was more effective than either LV or RV assist in restoring hemodynamic parameters; however, there was no difference in efficacy of LV and RV support. RV assist preserved left coronary flow patterns and chamber geometry compared to other assist conditions, but increased LV preload. These results suggest that LV and RV support each make a significant contribution to the efficacy of BiV assist, albeit through different mechanisms.