Effect of Geometry on the Leaflet Stresses in Simulated Models of Congenital Bicuspid Aortic Valves.

The aim of the study was to assess the effect of geometric variations on the stresses developed in the leaflets of congenital bicuspid aortic valves (CBAV). We developed a model for the human tri-leaflet aortic valve based on the geometry and dimensions published in the literature. We also developed simulated CBAV geometry based on the most common geometry present in patients with CBAV that is published in the literature. We employed a constitutive relationship for the leaflet material from the previously published experimental data of fresh porcine aortic valve leaflet specimens for the analysis. We performed dynamic finite element (FE) structural analysis of the valves in the aortic position in order to compute the strain and stress distribution on the leaflets of the tri-leaflet valve and the CBAV models. Our results showed that large changes in the computed in-plane leaflet strain and stress occurred with variations in the geometry of the simulated CBAV whereas changes due to alterations in material constants were correspondingly less. The valve orifice area in the fully open position was significantly reduced in CBAV compared to that for the tri-leaflet valve. The changes in geometry of CBAV resulted in large changes in in-plane strain and stress and our results suggest that geometrical variations may be a potential risk factor inducing calcific aortic stenosis frequently present in patients with CBAV.