Effect of LVAD outflow conduit insertion angle on flow through the native aorta

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Abstract
Background and aim: The goal of this study was to evaluate the effect of surgical anastomosis configuration of the aortic outflow conduit (AOC) from a continuous flow left ventricular assist device (LVAD) on the flow fields in the aorta using CFD simulations. The geometry of the surgical integration of the LVAD is an important factor in the flow pattern that develops both in series (aortic valve closed, all flow through LVAD) and in parallel (heart pumping in addition to LVAD). Methods: CFD models of the AOC junctions simulate geometry as cylindrical tubes that intersect at angles ranging from 30° to 90°. Velocity fields are computed over a range of cardiac output for both series and parallel flow. Results: Our results demonstrate that the flow patterns are significantly affected by the angle of insertion of the AOC into the native aorta, both during series and parallel flow conditions. Zones of flow recirculation and high shear stress on the aortic wall can be observed at the highest angle, gradually decreasing in size until disappearing at the lowest angle of 30°. The highest velocity and shear stress values were associated with series flow. Conclusions: The results suggest that connecting the LVAD outflow conduit to the proximal aorta at a shallower angle produces fewer secondary flow patterns in the native cardiovascular system.