Extremum-seeking control of left ventricular assist device to maximize the cardiac output and prevent suction

Abstract

The rotary blood pump is one of the latest generations of left ventricular assist devices (LVAD), helping patients to deal with shortage of cardiac output. The main challenge of the LVAD controller is to finely regulate the pump speed in a variety of physical activities from sleep (50 beats/min) till running (180 beats/min). If the pump speed exceeds the low/high extremes, the blood will inversely move (backflow), or the heart muscle will collapse (suction state). This paper shows that the LVAD behaves like a limit cycle and optimizing the amplitude of this limit cycle leads to improve the performance of the LVAD. Therefore, in this paper, a nonlinear controller is proposed based on extremum-seeking theorem in order to regulate the heart performance. The controller objective is to provide the maximum pump flow, while the suction phenomenon is prevented. This goal can be achieved by the proposed controller since it can assure reaching the extremum, taking into account the constraints for preventing suction. The control strategy is applied to an in-silico model, and the results declare that the proposed controller can maintain proper cardiac response, while the mean arterial pressure remains within the demanding range, preventing the suction. The controller's robustness is investigated under different levels of external noise, and the results are compared to the state-of-the-art approaches. The comparison results imply the superiority of the proposed approach to the counterparts.