Computational investigation of wall shear stress patterns on calcified aortic valve leaflets

Abstract

Background: Aortic valve diseases affect about 25% of the population over 65 years of age. Aortic valve separates the left ventricle from the aorta, and consists of three half-moon shaped leaflets. The leaflets are highly dynamic structures which open during the ventricle contraction and close during the ventricle relaxation. Calcification on leaflet surfaces results in poor valve functioning which deteriorates the valve hemodynamics. Wall shear stresses (WSS) on the leaflet surfaces are considered to be strongly related with the initiation and progression of calcification. Aim: To investigate the effect of altered hemodynamics on the valve leaflet calcification, and to understand the role of WSS patterns in the progression of the aortic valve diseases. Methods: We investigate the hemodynamics of aortic valves using computational modeling. Fluid-structure interaction approach is employed to accurately determine the complex dynamic motion of valve leaflets. A 3D patient-specific aortic valve model is generated. Using finite element modeling, blood flow velocities, pressures, and WSS values are determined within the entire model, employing numerical techniques to obtain the characteristics of altered hemodynamics and spatial WSS patterns. Results: In case of calcification, WSS values are increased at both surfaces of the leaflets. On the ventricularis surface, there is a spatially-regular WSS distribution, which gradually increase from the leaflet attachment region to the leaflet tip. However, a spatially-complex WSS distribution is observed on the aortic leaflet surface. Conclusion: Relatively low WSS levels and spatially-complex WSS patterns on the aortic leaflet surface are observed as potential risk factors for the initiation and progression of aortic valve calcification