Aortic Hemodynamics of Spiral-Flow-Generated Mechanical Assistance.

Mechanical circulatory support (MCS) devices are being increasingly used as destination therapy in end-stage heart failure patients. Although current devices have significantly improved survival rates, the resulting hemodynamics remains non-physiological. Spiral forms of blood flow are known to exist in the large arteries (e.g., aorta) and serve as a biomimetic-motivation for generating these physiologically-adapted flow regimes. This research aimed to study the potential benefits of generating spiral flow at the MCS outflow graft and the resultant flow-fields in the aorta, including recirculation zones and endothelial wall shear stress (WSS) areas.A 3D-model of an outflow graft virtually anastomosed end-to-side to an image-derived aortic arch was used in computational fluid dynamic simulations. To study the impact of both spiral flow modulation (clockwise/counter-clockwise helical-flow content) and the outflow graft anastomosis angle (inferiorly/superiorly-directed, anteriorly/posteriorly-directed), flow velocities were measured, low/high-WSS were computed, and fluid streamlines were visualized.Increased helical-flow content reduced regions of low-velocity (<5cm/s), minimized areas exhibiting low-WSS (<3dyn/cm), and concomitantly increased areas of high-WSS (>80dyn/cm). The outflow graft anastomosis angle was a key determinant of aortic root washout and fluid-jet wall impingement. Despite counter-clockwise spiral flow predominance in diminishing the size of recirculation/stasis zones compared to straight/clockwise flow, exceptions to this were noted with the superiorly-directed and posteriorly-directed graft placements.Spiral flow-forms better tailored to the underlying three-dimensional aortic curvature and graft angle positioning is expected to help attenuate atherogenesis, preventing vascular remodeling and minimizing plaque formation/erosion in mechanically assisted circulation.