A Mathematical Model of Artificial Pulse Synchronization for the HeartMate3 Left Ventricular Assist Device

Constant speed control of rotary LVADs attenuates vascular pulsatility, which has been linked to clinical complications such as thrombus formation, bleeding, and valvular dysfunction. Speed modulation can improve pulsatility and washout, but optimization requires coordination with the native heartbeat. A simple mathematical model of the left ventricle-left ventricular assist device (LV-LVAD) flow interaction was developed that sums the individual contributions of the native LV and the HeartMate3 artificial pulse (AP) to predict the total systemic flow. The model flow and pulsatility predictions results were in good agreement with experimental data from a mock circulatory loop measured for full bypass support conditions. The model was used to evaluate three schemes for optimizing the synchronization of the AP with the native heart. The optimized interaction occurred when the AP speed increase occurred during contraction, resulting in a doubling of flow pulsatility, and corresponded to an increase in the area enclosed by the dynamic pressure-flow relation. The model provides a simple tool for exploring the optimization of LVAD speed modulation that can reduce the time and expense of mock loop studies during the development process.