Hemodynamic controller for left ventricular assist device based on pulsatility ratio.

Hemodynamic control of left ventricular assist devices (LVADs) is generally a complicated problem due to diverse operating environments and the variability of the patients: both the changes in the circulatory and metabolic parameters as well as disturbances that require adjustment to the operating point. This challenge is especially acute with control of turbodynamic blood pumps. This article presents a pulsatility ratio controller for LVAD that provides a proper perfusion according to the physiological demands of the patient, while avoiding adverse conditions. It utilizes the pulsatility ratio of the flow through the pump and pressure difference across the pump as a control index and adjusts the pump speed according to the reference pulsatility ratio under the different operating conditions. The simulation studies were performed to evaluate the controller in consideration of the sensitivity to afterload and preload, influence of the contractility, and effect of suction sensitivity. The controller successfully adjusts the pump speed according to the reference pulsatility ratio, and supports the natural heart under diverse pump operating conditions. The resulting safe pump operations demonstrate the solid performance of the controller in terms of sensitivity to afterload and preload, influence of the contractility, and effect of suction sensitivity.