UC Riverside

Flow diverters are being increasingly used as an option of treatment for intracranial aneurysms. These devices are deployed endovascularly along the parent artery where an aneurysm is located. It takes advantage of the intra-aneurysmal hemodynamics to occlude the aneurysm by reconstructing the parent artery over time, replacing diseased tissue new healthy tissue. Although these minimally invasive, low porosity devices are being widely used for aneurysmal treatment, there are concerns around inefficiency associated with the high level of curvature in cerebral arteries. Some studies suggest that the inertia driven flow in tortuous arteries

compared to the shear driven flow in the straight artery is the cause of inconsistent device performance. Previous research in our lab has indicated the potential of a novel microfabricated, solid construct balloon-deployable flow diverter within the posterior cerebral circulation. Presented herein, we demonstrate the effectiveness of these novel devices in tortuous parent arteries using computational fluid dynamic studies. We computed and compared the intra-aneurysmal hemodynamics for the stented and unstented cases of the tortuous geometry using ANSYS Fluent 18.2. The numerical results indicate higher flow velocities and wall shear stress inside the aneurysmal sac as the tortuosity of the parent artery increases, which imply the presence of inertial flow in the tortuous models. Reduction of intra-aneurysmal velocity and wall shear stress are considered as the key hemodynamic parameters which promote thrombosis of aneurysmal tissue. Results after implantation of stents displayed substantially reduced values of inflow velocity and wall shear stress inside the aneurysm sac for all the studied models. Significant reductions were seen when high aspect ratio struts were computed at lower porosities in the straight as well as tortuous models. Values of velocity and wall shear stress reduction as high as 95% were observed with high aspect ratio struts at lower porosities. This indicates the efficient working of the high aspect ratio struts in the inertial flow regions of the tortuous parent arteries. The favorable outcome of this simulation is encouraging to further explore this device in more variations of aneurysm and parent vessel geometries.