Automatic control of a series-parallel mechanical circulatory assist system in severe uni- or biventricular failure.

Abstract

Conventional peripherally invasive mechanical circulatory assist methods such as intra-aortic balloon pumping are of only limited hemodynamic benefit in cases of severe left ventricular failure. This article deals with the analysis and testing of a new pumping concept (16), that is theoretically capable of providing adequate circulatory and respiratory assistance in cases of severe uni- or biventricular failure. This assist system combines an intra-aortic balloon pump (a series form of left ventricular assistance) and pulsatile venoarterial membrane oxygenator bypass (a parallel mode of assistance). The combined pulsatile assist system is controlled by a digital microprocessor which provides appropriate phasing relative to the R wave of the ECG. This support system requires only cannulation of femoral or other easily exposed vessels. Blood-gas exchange gas diffusion or massive pulmonary embolism or other perfusion defects. This concept has been tested in a series of experiments with canine models of ventricular failure. The results of this study indicate that (1) balloon pumping becomes much more effective when combined with pulsatile veno-arterial bypass in cases of severe ventricular failure with an attendant hypotensive circulatory state, and (2) the automatic control system is effective in optimizing the performance of the combined assist system.