Design and development of a combined cardiovascular assist system for support in severe ventricular failure
Peterson, Robert L.
Clark, John W.
Master of Science
This thesis work documents the design and testing of a ventricular assist system combining intra-aortic balloon pumping (IABP) with partial veno-arterial bypass (VABP), both pulsatile and nonpulsatile. A series of animal experiments was carried out after verification of the concept on a mock circulation. Although statistical significance was not obtained, the results were encouraging. This system combines the beneficial features of the two devices in a synergistic manner to obtain a system capable of total body support while at the same time improving the viability of the damaged myocardium. IABP, itself incapable of supporting the circulation in severe heart failure, is used to reduce the afterload caused by VABP, which can provide more profound circulatory assistance. Diastolic augmentation by pulsatile VABP enhances that due to IABP, and there is further enhancement of IABP function due to increased mean arterial pressure. A decrease in heart preload pressure was seen which reflected the decreased venous return brought about by bypass. Thus, in spite of increased total body perfusion, cardiac output was diminished. The decrease in cardiac output was sufficient to reduce heart flow work even though there was an increase in afterload pressure. Finally, the state of the animal seemed to be improved by the assist system in that arrhythmia and mortality were decreased during combined assistance.