Effect of Bileaflet Valve Orientation on the 3D Flow Dynamics in the Sinus of Valsalva

Three-dimensional (3D) evolutional behavior of flow dynamics in the aortic sinus of Valsalva was studied in vitro for finding the effects of bileaflet valve orientations in an effort to investigate possible linkages between the sinus flow and coronary circulation. A realistic model of the aortic sinus was machined inside an acrylic block. A St. Jude Medical bileaflet aortic valve was utilized. Two orientations were compared; (1) a pair of hinges aligned in the direction of the non-coronary sinus of the model (N0) and (2) of the left and right sinuses (N90). A 3D scanning three-component velocity measurement, named Fluorescent Scanning Stereoscopic Particle Image Velocimetry (FS-SPIV), was developed. Measured data were validated with an aid of two-dimensional particle image velocimetry. Good agreement confirmed the capability of quantifying the 3D mean and turbulent behavior of sinus vortices. The valve orientation was found to be unable to affect the sinus vortices during peak-systole, but had a substantial impact on regurgitation during end-systole. The superior case (N0) gave a symmetric regurgitation. The regurgitant jet was directed to the non-coronary sinus. The left and right sinuses were dominated by a well-organized recirculation from a persistent forward flow. The inferior case (N90) produced an asymmetric regurgitation with a biased jet into the left or right sinuses, leading to produce unexpected turbulence near the entrance of coronary artery. Those results suggest possible linkages between the sinus flow and coronary circulation, thereby advocating the existence of an optimal orientation of bileaflet valves.