A Blood Assist Index Control by Intraaorta Pump: A Control Strategy for Ventricular Recovery

Left ventricular assist devices (LVAD) are increasingly used for long-term support in heart failure patients. To promote ventricular reverse remodeling, a defined and adjustable energy distribution of LVAD and native heart is important. Therefore, a blood assist index (BAI), which is a ratio of power of LVAD and total power of the cardiovascular system, is defined to indicate the energy distribution of LVAD and native heart. Subsequently, an LVAD control algorithm that uses the BAI as control input is designed. The control strategy maintains the measured BAI tracking the desired BAI. A mathematic model of cardiovascular system is used to verify the feasibility of control strategy in the presence of left ventricular failure, physical active, and a recovery of cardiac function. The simulation results show that the control strategy automatically increases pump speed in response to the reduced peripheral systemic resistance (5,500 vs. 6,000 RPM). When E-max is increased from 0.6 to 1.8 mm Hg/ml to mimic left ventricular recovery, the blood flow is automatically increased from 5 to 8 L/min. As a key feature, the proposed control strategy provides a defined and adjustable energy distribution of LVAD and native heart by regulating the rotational speed of the pump, which is benefit to promote the left ventricular reverse remodeling. ASAIO Journal 2011; 57:358-362.