Abstract
Background and Aim: One of the major concerns with the use of circulatory assist devices (CADs) is their performance during the transition from supine to standing position. In standing position, vasodilatation of veins occurs in the legs, which decreases left ventricular end-diastolic pressure, and, in turn, the preload to the CAD. This research numerically studies the physiological interaction of pulse left ventricular assist devices (LVADs) in relation to cardiac output and stroke volume under systolic and diastolic situations.

Methods: A cardiovascular system (CVS) model was used to configure the output of heart failure (HF) status by changing system parameters in one cardiac cycle, whereas LVAD pump was configured to change the fixed rotational speed. The terms of the pump cannulae model, real-time detection of aortic valve status, left ventricular stroke volume analysis, and LVAD control method were designed and analyzed.

Results: The results showed that end-diastolic left and right ventricular volumes – pressures in heart failure condition were reduced from 183 mL to 164 mL with continuous fixed speed RBP support, Alongside with a corresponding increase in ejection fraction (16%).

Conclusions: The results show that LVADs are more sensitive to preload than afterload when operating at a fixed speed.

Key words: Heart Failure, Rotary Blood Pumps, Cardiac Output, Cardio-vascular System.