Experimental analysis of the effect of thickness and protrusion height on the cinematics of bio-inspired polymeric heart valves leaflets – amplitude and frequency response

Despite their advantages as prosthetic devices, polymeric heart valves (PHV) are not adequate for clinical use due to their susceptibility to fatigue. The vibrations of heart valve leaflets during systole are commonly attributed to a viscoelastic phenomenon called flutter, which is associated with valve calcification and fatigue. Therefore, it is crucial to study how the geometric features of PHVs affect leaflet kinematics and fatigue. However, despite this importance, all PHV in vitro studies in literature have restricted their analyses to global parameters associated with PHV hemodynamic performance. The kinematics of PHV leaflets have never been analyzed individually in experimental studies. This study proposes using high-speed filming to analyze the amplitude and frequency of 8 bio-inspired polymeric heart valves manufactured with different leaflet thicknesses and protrusion heights. In addition to analyzing the sensitivity of leaflet vibrational movement to changes in thickness and protrusion height, this study aims to provide initial insights into the theoretical classification of the mechanism responsible for fluid-induced vibration in heart valves. Our findings indicate that each valve’s leaflet may exhibit asymmetric vibrational movement with varying sensitivity to geometric feature alterations. Notably, valve oscilattions are more sensitive to changes in protrusion height than to changes in leaflet thickness. Regarding the investigation of the excitation mechanisms of fluid-induced vibration in heart valves, we found no evidence of flutter according to the available literature criteria. The excitation mechanism of the fluid-induced vibration observed in all the tested valves was Extraneously Induced Excitation and Instability Induced Excitation.