NUMERICAL STUDY OF BLOOD FLOW AT THE END-TO-SIDE ANASTOMOSIS OF THE LEFT VENTRI

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Left ventricular assist devices (LVADs)have been used extensively to assist or replace the function of a failing left heart. The LVAD is usually connected to the native heart between the apex of the left ventricle by the LVAD inflow cannula and to the aorta by the LVAD outflow cannula. Depending on the state of the heart, the LVAD can work in either serial or parallel conditions.Blood flow in the aorta can be highly disturbed by the anastomosis. A descending aortic outflow anastomosis is usually not employed due to its potential to generate stagnant flows associated thrombosis near the aortic valves (DiGiorgi et al., 2004). An ascending aortic anastomosis, however, can produce highly disturbed flows in the aorta, resulting in jet impingement on the aortic arch, unpredictable flow partitioning between the major secondary vessels, stagnant flow near the aortic root, and even turbulent flow under specific operating conditions. These high shear turbulent flows might cause platelet activation and hemolysis. Therefore, it is important to study flow patterns in the aorta based on different LVAD anastomotic configurations.The goal of the present study is to understand the influence of the outflow cannula anastomosis, in continuous and pulsatile flow conditions, using an object-oriented CFD software toolkit OpenFOAM (Open Field Operation and Manipulation) to compute the flow field. Both laminar and turbulent flows are studied under serial and parallel conditions. The aorta is assumed to be curved in one plane only. The flow partitioning between the secondary vessels is modeled by applying a resistance outflow boundary condition (Figueroa et al., 2006; Vignon-Clementel et al., 2006). Two different outflow cannula anastomotic configurations, including both proximal and distal positions, are considered.