The effect of control condition of ventricular assist device on the response of cardiac output to venous blood return

The cardiac functions including the autoregulation such as Frank-Starling preload response is depressed in heart failure. Although ventricular assist device (VAD) contributes to reduce ventricular load and increase cardiac output, the effect of VAD on depressed preload response has not become clear. In this study, the effect of control conditions and performance curve of blood pump on the preload sensitivity was investigated using numerical simulations. The preload sensitivity was defined as maximum change in cardiac output when right atrial pressure was changed from circulatory equilibrium in the simulations. Furthermore, animal experiment was performed in order to verify the result of the simulations. The preload sensitivity of pump flow changed depending on pump characteristic. Conversely, that of total flow was almost the same with various pump characteristics at partial bypass condition. Results indicated that it is necessary to introduce some active control to improve the sensitivity.