Physiologic control of rotary blood pumps by ventricular chamber size estimation using resonantly coupled sensors

Rotary blood pumps (RBP) currently operate at a fixed pump speed and are unable to meet physiologic demand and susceptible to ventricular suction. To overcome this limitation, we developed a left ventricular end-diastolic volume (EDV) based physiologic control algorithm using resonantly coupled high-efficiency sensors. The resonantly coupled sensors consist of apical and outflow sensors that can accurately assess the ventricular chamber size with minimal long-term drift (∼1 %) at 9 months. The ability of the control algorithm was evaluated using an in-silico circulatory system model coupled to an axial or centrifugal flow RBP with 15 % uniformly distributed measurement noise. The EDV setpoint was set to 85 ml, and the efficacy of the EDV control algorithm was evaluated and compared to maintaining a constant pump speed during (1) rest and exercise; (2) rapid, eight-fold augmentation of pulmonary vascular resistance; and (3) rapid transitions between rest and exercise. Safety and robustness of the algorithm was also evaluated by assuming a 6 % volume drift. The EDV control algorithm provided sufficient physiological perfusion and avoided ventricular suction in all cases. Performance of the EDV algorithm was superior compared to maintaining constant pump speed for both types of RBP, demonstrating pump independence of the proposed algorithm.