Effect of leaflet shape on the left ventricular blood flow pattern in BMHVs

When a bileaflet mechanical heart valve is surgically implanted into the body, the downstream left ventricular blood flow pattern becomes complex, which is directly related to many postoperative complications. To investigate the hemodynamic properties associated with mechanical heart valve design, we built a left heart circulatory pulsatile flow generation system to simulate left ventricular flow and pressure under physiological conditions. We used time-resolved particle image velocimetry to study left ventricular blood flow downstream of two types of bileaflet mechanical heart valve: one with planar leaflets and one with cambered leaflets. Blood flow downstream of two different bileaflet mechanical valve shapes was assessed. The experimental results show that the bileaflet valve with a triple-jet pattern creates a three-dimensional vortex ring with a complex topology. In addition, the robust jet mode can introduce high shear stresses into the ventricular blood flow. Compared with the planar valve, the jet produced by the cambered valve has a more uniform velocity distribution, its vortex structure moves farther, and its shear stress distribution is more straightforward and continuous. Furthermore, the channel formed between the cambered valve vortex structure and the left ventricle wall surface is highly favorable for scouring the apical position and facilitating the transport of blood to the aortic orifice. Therefore, the shape of the leaflets of a bileaflet mechanical valve can significantly impact the left ventricular blood flow pattern and the blood transport process. Rational optimization of the design of the leaflet shape and improvement of the mechanical valve's hemodynamic characteristics can reduce complications after valve replacement.