On the role of aortic valve architecture for physiological haemodynamics and valve replacement. Part I: flow topology and vortex dynamics

Abstract

Aortic valve replacement has become a growing concern due to the increasing prevalence of aortic stenosis in an ageing population. Existing replacement options have limitations, necessitating the development of improved prosthetic aortic valves. In this study, flow characteristics during systole in a stenotic aortic valve case are compared with those downstream of two newly designed surgical bioprosthetic aortic valves (BioAVs) using advanced simulations. Our findings reveal that the stenotic case maintains a high jet flow eccentricity due to a fixed orifice geometry, resulting in increased vortex stretching in the commissural low-flow regions. One BioAV design introduces non-axisymmetric leaflet motion, which reduces the maximum jet velocity and forms more vortical structures. The other BioAV design produces a fixed symmetric triangular jet shape due to non-moving leaflets and exhibits favourable vorticity attenuation and significantly reduced drag. Therefore, this study highlights the benefits of custom-designed aortic valves in the context of their replacement through comprehensive flow analyses. The results emphasise the importance of analysing jet flow, vortical structures, momentum balance and vorticity transport for evaluating aortic valve performance.