Effects of implantation techniques and vortex shedding on free emboli formation in mechanical heart valves

A numerical analysis of pulsatile turbulent flow was conducted past a St. Jude Medical MHV in the aortic position, to study the effects of valve implantation technique on the thromboembolic potential of the valve. The simulation focussed on the assumption that by altering the flow fields past the valves, the valve orientation and the suturing technique employed have a favorable or undesirable effect on the thromboembolic potential of the valve. It was demonstrated that the combination of a valve that is not aligned with the axis of the blood flow and subannularly sutured pledgets, produced accelerating jet flow through the valve orifices and a wider wake of periodic shed vortices in the valve's leaflets wake. The existence of the shed vortices was confirmed by Digital Particle Image Velocimetry (DPIV). measurements. Platelets paths that exposed the platelets to the highest shear levels led them to entrapment within the shed vortices, indicating that the risk of cardioembolism will be enhance.