Analysis on the effects of hypo-attenuated leaflet thickening on the hemodynamics of transcatheter aortic valve prostheses by means of particle image velocimetry

Abstract

Abstract The minimally invasive therapy for the treatment of aortic valve regurgitation and stenosis, transcatheter aortic valve replacement (TAVR), is an alternative to surgical valve replacement. Promising clinical results led to the consideration of expanding the use of TAVR in younger patients with lower surgical risk. This implies a longer durability of the TAVR. In relation to the durability of the TAVR, thickening of TAVR leaflets, including reduced motion, has been clinically observed. The aim of this study was to analyse the effects of valve leaflet thickening with reduced leaflet kinematics on the hemodynamics. We measured the flow through a TAVR under pulsatile conditions by using phase-resolved particle image velocimetry (PIV). It has been shown that flow conditions alter in a pathological manner in a TAVR replica with thickened leaflets compared with thin leaflets. In detail, shear stress and Reynolds stress increased by up to a factor of two and additionally the washout behaviour was worse for thickened leaflets. This suggests that a thickened valve is at higher risk for platelet activation and aggregation. This could lead to a self-reinforcing process in which the formation of a thickened valve promotes thrombus formation, which in turn promotes further progression of the thickening.