Mechanical simulation of cardiac function by means of pulsatile blood pumps

After a review of the theoretical and experimental background, a history of the development of pulsatile blood pumps is presented with an attempt to understand the underlying rationale. The case for the use of pumps that simulate normal cardiac function is made by considering cardiovascular hemodynamics, the function of arterial baro-receptors, hemodynamic energy and power, tissue fluid movement, and lymph formation and flow. The pulsatile output of the heart and mechanical pumps is described in units of power and the load that they work against as a complex impedance. Many pulsatile pumps have been designed and developed for research, but few have been used during cardiac operations on human patients. The evidence in favor of using pulsatile flow for cardiopulmonary bypass is strong, but major problems have been identified such as the lack of a satisfactory definition of pulsatile flow and technical difficulties resulting from impedance mismatches in clinical applications.