Analog Simulation of Left Ventricular Bypass Mode Control

The subject of this study is optimal mode control for the left ventricular bypass pump used to assist the failing heart. A mathematical model has been formulated for the overall cardiovascular system both with and without bypass assistance. The closed-loop, uncontrolled model of the unassisted circulation has been implemented on an analog computer and has been demonstrated capable of simulating normal as well as abnormal physiological behavior. A simple bypass pump model has been implemented and shown to produce the general hemodynamic effects expected during assistance: pressure in the left atrium is diminished while that in the systemic arterial load is increased. Four logical modes of pump control have been described and compared on the basis of their effect upon a scalar performance index used to reflect the basic goals of cardiac assistance.