EXPERIMENTAL STUDY ON HEMODYNAMICS OF AORTIC VALVE UNDER VARIED CARDIAC OUTPUT USING PIV

Reduced cardiac output (CO) always occurs in aortic valve diseases. The hemodynamics of aortic valve is affected by reduced CO, causing secondary valvular diseases. In this paper, a three-dimensional reconstruction of aortic root geometric model with left coronary artery is complished based on medical imaging data, a highly smooth and transparent aortic root experimental model is casted, and an in vitro pulsating circulation system is constructed. Particle image velocimetry (PIV) is used to investigate the effect of CO on hemodynamics of aortic valve with or without the left coronary artery, such as the velocity, viscous shear stress (VSS), Reynolds shear stress (RSS), and so on. The results show that aortic sinus hemodynamics are influenced by left coronary artery that the presence of left coronary artery changes the vortex and vorticity in the sinus. In the case of the presence of left coronary artery, fluids in the aortic sinus flows out through the left coronary artery which leads to vortex gradually disappears and vorticity early decreases. At the peak systolic, regions of positive and negative VSS are exist in both sides of the centrosymmetric systolic jet and RSS is especially elevated in the ascending aorta on the side of left coronary artery. In addition, the hemodynamics of aortic valve, such as the velocity, VSS and RSS, are significantly affected by the CO. The maximum velocity, VSS and RSS increase with the increasing of CO, namely, the maximum velocity is 0.98, 1.13, 1.21 and 1.37 m/s, the maximum VSS is 0.87, 0.95, 0.96 and 1.02 N/m^2, and the maximum RSS is 103.76, 116.25, 138.68 and 146.55 N/m^2 when CO=2.1, 2.8, 3.5 and 4.2 l/min, respectively. At low CO, the values of transvalvular flow velocity and VSS of aortic valve are small, which may easily lead to thrombosis. The research findings can provide theoretical references for the aortic valve implantation.