Real-time physiological environment emulation for the Istanbul heart ventricular assist device via acausal cardiovascular modeling

Abstract

Background and objectives: The cost and complexity associated with animal testing are significantly reduced by using mock circulatory loops prior. Novel mock circulatory loops allow us to test biomedical devices preclinically due to their flexibility, scalability, and cost-effectiveness. The presented work describes the development of a hardware-in-the-loop platform to emulate human physiology for the Istanbul Heart (iHeart-II) LVAD. Methods: A closed-loop system is developed whereby the effect of the LVAD on the heart and vice versa can be studied. An acausal model of the cardiovascular system is calibrated to emulate advanced-stage heart failure. A new prototype of the iHeart-II LVAD is connected between two air-actuated chambers emulating the left ventricle and aortic chambers with PID controllers tracking numerically modeled pressures from the in silico model. A lead-lag compensator is used to maintain fluid level. Controllers are tuned using nonlinear Hammerstein-Weiner models identified using open-loop data. The iHeart-II LVAD is operated at various speeds in its operational range, and the resulting hemodynamics are visualized in real time. Results: Hemodynamic variables, such as LVAD flow rate, aortic, left ventricular, and pulse pressure, demonstrate trends similar to clinical observations. The iHeart-II LVAD achieves hemodynamic normalization at similar to 3500 rpm for the emulated condition. Conclusions: A novel evaluation methodology is adopted to study the performance of the iHeart LVAD under advanced-stage heart failure emulation. The models and controllers used in the platform are readily replicable to facilitate VAD research, pedagogy, design, and development.