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The experiments and CFD results suggest that there is negligible difference in the outflow rates to a branch vessel in antegrade and retrograde directions for 40-mm-long conduits. However, for a 200-mm conduit, the flow to a branch vessel through the retrograde path is lower than for the antegrade direction, which has implications for the insertion of branches to stent-grafts and extra-anatomical surgical bypass for visceral revascularization.

Cerebral aneurysms can be treated by coil embolization within the aneurysm sac to alter the local hemodynamics and lower the wall shear stress (WSS) by making the aneurysmal flow inactive. This study investigates the hemodynamics of a lateral wall cerebral aneurysm with coils incorporating fluid-structure interaction (FSI) where the effect of apparent viscosity on thrombus formation is analysed considering the non-Newtonian behaviour of the blood. Three-dimensional transient incompressible laminar flow fields were predicted inside the aneurysm with coils at the proximal and distal neck ends with straight and curved parent vessels. The predictions showed the WSS and the effective stress were highest at the neck region, but the maximum wall displacement occurred at the dome. The coils at the distal neck performed better compared to the coils at the proximal neck in terms of reduced flow rate and higher apparent viscosity. The cerebral aneurysm with coils and curved parent vessel was subjected to higher inflow, displacement and WSS but lower apparent viscosity compared to the one with a straight parent vessel, and therefore has a greater risk of aneurysm wall damage. Hypertension increased the effective stress and displacement on the aneurysm. In patients with hypertension, more emphasis should be placed on ensuring that coils are densely packed at the distal end, especially for curved parent vessels.