Simulation of Aortic Valve Dynamics during Left Ventricular Support

Abstract

Implantable Rotary Blood Pumps (IRBPs) for the left ventricle (LV) have become a viable treatment and long-term option for heart failure (HF) patients. In addition, development of valve abnormalities after Left Ventricular Assist Device (LVAD) implantation is common among patients with advanced HF, likely due the fact that the LVAD alters haemodynamics by changing the direction of blood flow from the apex of the heart, largely bypassing the left ventricle (LV), directly to the aorta. The aim of this thesis was to investigate the hemodynamic interaction between the LVAD and aortic valve (AV) using 2D LV LVAD computational models.

To investigate the correlation between AV status and LVAD motor speed, this study perfomed a detailed computational analysis of left ventricular flow and mechanics during LVAD support. Simulations were carried out using a 2D LV-pump Fluid-Structure Interaction (FSI) approach, examining LVAD intrinsic motor current and motor speed waveforms. AV state was assessed by analysing the pump motor current waveform, investigating its association with open-close valve state and pump impeller speed. Results show that there is a significantly higher motor current during the valve open state, which has the potential of being utilized in future LVAD control systems to ensure patient safety and comfort, and reduce the incidence of AV pathologies during heart pump support, as well as for optimal management of pump outflow, paving the way for more sophisticated pump control algorithms, which take into account heart valve state.