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An investigation on the effects of chamber wall's elasticity on blood flow in a LVAD pump

Abstract

Left Ventricular Assist Device (LVAD) is a pump that is designed to provide life support to patients with end stage heart failure. In an effort to ensure the safety of LVAD, the pumping mechanics must not exert excessive stress on the blood or hemolysis would occur. This study investigates the effects of chamber wall's elasticity (isotropic) from common materials on blood flow in a LVAD, especially the shear stress resulted therein. The materials considered are titanium, diamond-like carbon (DLC), 2-methacryloyloxy ethyl phosphorylcholine (MPC) polymer, segmented polyurethane (SPU), polyurethane (PEU), and a material with properties corresponding to blood vessels, which is used as the reference. The study employs a Fluid Structure Interaction (FSI) simulation software suite to couple Computational Fluid Dynamics (CFD) with mechanical simulation (ANSYS). The test system is a centrifugal pump based on a 2012-Jarvik Patent. The flow through the pump is driven by an impeller rotating at set speed to achieve a pre-set blood flowrate. The results show that there is no significant difference in turbulent dissipation rate among the different chamber-wall materials, with PEU giving closest figure to the blood vessels'. On the other hand, regarding wall shear stress which is an important factor in hemolysis, titanium, DLC and SPU result in similar maximum values, whereas MPC, PEU and blood vessel material give noticeably lower ones

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