oa Experimental and Computational Studies of the Aortic Bi-leaflet Mechanical Heart Valve (BMHV) Hemodynamics in an Idealized Left Ventricle

We aim to validate the performance of our fluid structure interaction (FSI) simulations of a bi-leaflet mechanical heart valve in the aortic position., whose motion is driven by the beating left ventricle. We compare in vitro experiments and computations performed on an idealized model of the left ventricle (LV) with a St. Jude Medical Regent heart valve in the aortic position. The idealized LV consists of a truncated tetrahedron representing a simplified LV chamber with a single deformable surface made of silicone. The silicone surface simulates the lateral wall of the LV. The deformation of the LV is controlled by pressurizing the fluid surrounding the LV chamber via a Vivitro Superpump (Vivitro Systems; British Columbia). The experimental model simulates physiological flow rates and pressures that occur in the LV. The three-dimensional motion of the deformable surface is tracked using high speed cameras and reconstructed using a direct linear transformation. The reconstruction of the motion of the deformable surface has been validated against fluid volume flux of the LV measured using two Transonic Systems Inc. flow probes (Model ME-PXN; Ithaca, NY). The leaflet motion of the SJM is tracked using 2D photogrammetry with a single high speed camera. A two-dimensional DPIV system (LaVision GmbH; Goettingen, Germany) is used to acquire fluid velocity measurements within the ventricle and in the aortic position of the flow field through the cardiac cycle. In the computation, the ventricle kinematics, measured from experiment, is treated as an immersed boundary by the Curvilinear Immersed Boundary (CURVIB) method ( Ge et al., J. Comp. Physics, 2007). The leaflet kinematics of the BMHV are computed from the fluid-structure interaction solver FSI-CURVIB (Borazjani et al., J. Comp. Physics, 2008). The computational domain is a structured mesh of 8 million grid points with a physical timestep of 1 ms. We have previously shown the capability of the FSI solver to resolve the BMHV kinematics and the resulting flow patterns in a stand-alone aorta (Borazjani et al., J. Comp. Physics, 2008). The comparison between the experimental and computational results shows good agreement for the ventricular flow pattern. The details of the validation of coupled LV-BMHV simulations will be discussed in the presentation.