Peak Flow in Model Aorta Through Bi-Leaflet Mechanical Heart Valve with Varying Orientation

This study aims to numerically investigate the effect of bi-leaflet mechanical heart valve (BMHV) orientation on flow pattern in a realistic human aorta model with branches. The aorta model geometry is based on anatomical shape and dimensions involving aortic arch with twist and branches. Unsteady numerical simulations have been carried out to investigate the peak systolic flow in aorta through a BMHV installed at three different orientations, marked as 0°, 45°, and 90°. Velocity, vorticity, and strain fields were obtained in various cross sectional planes for all the cases to examine the spatial flow evolution starting from the sinus along the aortic arch. The valve leaflets were seen to produce small-scale stream wise contra-rotating vortices. These vortices changed their positions around the axis of aorta while advecting from one cross-sectional plane to another; thereby, clearly indicating swirl in the aortic flow. The net viscous dissipation energy loss (EL), obtained from strain field, was found to rise because of the presence of BMHV. The increase in the EL varied depending on the valve orientation as it changed from 43% for 0° to a maximum of 53% for 90° compared with no valve case. Similarly, the wall shear stress registered an increase by up to 4 Pa in the ascending aorta because the presence of BMHV; however, no significant effect of the valve orientation was noticed.