Impact of Bileaflet Mechanical Heart Valve implantation angle on left ventricular hemodynamics and blood cell damage

<i>Purpose:</i> The implantation angle of Bileaflet Mechanical Heart Valve (BMHV) is critical issue in valve replacement surgery. Investigating the local hemodynamic characteristics and analyzing the postoperative flow dynamics can provide valuable insights for determining the optimal implantation angle, thereby offering clinical guidance for improved surgical outcomes. <i>Methods:</i> Three-dimensional anatomical model of the Left Ventricle (LV) and BMHV was reconstructed based on patient-specific medical imaging data and anatomical parameters. The hemodynamic effects of varying implantation angles were investigated using Computational Fluid Dynamics (CFD) integrated with a Fluid-Structure Interaction (FSI) framework. <i>Results:</i> The key analyses focused on the downstream shear stress distribution, vortex dynamics, clinically relevant hemodynamic indicators. When the valve was implanted along the axis of the aortic outflow tract (referred to as the AO angle), several benefits were observed. Blood flow penetrability improved, high shear stress regions were reduced, mechanical trauma to blood cells was significantly lessened. Quantitative metrics further demonstrated that the AO angle minimized values of Time-Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI) and Relative Residence Time (RRT). These metrics indicate more stable hemodynamics and a lower risk of ventricular wall inflammation and thrombosis. Furthermore, the Hemolysis Index (HI) reached its lowest level under the AO angle, suggesting optimal mitigation of hemolysis. This study systematically examines how the orientation of BMHV implantation affects LV hemodynamics. It identifies the AO angle as the most effective strategy for positioning. <i>Conclusions:</i> These findings provide quantitative evidence that can inform preoperative planning and support the advancement of precision-guided cardiac valve interventions based on hemodynamics considerations.