A computational study on the influence of aortic valve disease on hemodynamics in dilated aorta

A computational hemodynamics method was employed to investigate how the morphotype and functional state of aortic valve would affect the characteristics of blood flow in aortas with pathological dilation, especially the intensity and distribution of flow turbulence. Two patient-specific aortas diagnosed to have pathological dilation of the ascending segment while differential aortic valve conditions (i.e., one with a stenotic and regurgitant RL bicuspid aortic valve (RL-BAV), whereas the other with a quasi-normal tricuspid aortic valve (TAV)) were studied. When building the computational models, in addition to in vivo data-based reconstruction of geometrical model and boundary condition setting, the large eddy simulation method was adopted to quantify potential flow turbulence in the aortas. Obtained results revealed the presence of complex flow patterns (denoted by time-varying changes in vortex structure), flow turbulence (indicated by high turbulent eddy viscosity (TEV)), and regional high wall shear stress (WSS) in the ascending segment of both aortas. Such hemodynamic characteristics were significantly augmented in the aorta with RL-BAV. For instance, the space-averaged TEV in late systole and the wall area exposed to high time-averaged WSS (judged by WSS> two times of the mean WSS in the entire aorta) in the ascending aortic segment were increased by 176% and 465%, respectively. Relatively, flow patterns in the descending aortic segment were less influenced by the aortic valve disease. These results indicate that aortic valve disease has profound impacts on flow characteristics in the ascending aorta, especially the distribution and degree of high WSS and flow turbulence.