In vitro and in silico studies of Flow Diverting Stents for Intracranial Aneurysms

Flow Diverting Stents (FDS) are high porosity (~70%) tubular meshes that are deployed in cerebral arteries for the treatment of intracranial aneurysms. They aim at lowering both the inflow and the blood velocity in the aneurysmal sac, promoting thrombus formation to isolate the wall from mechanical stresses and prevent rupture. Previous experimental work has demonstrated the negative effect of parent vessel curvature on treatment effectiveness, as it both impacts the inflow and the porosity of the FDS. Numerical simulations are widely used for patient-specific analysis of aneurysm treatment, but they require the use of a model for the FDS, which is very often modelled as a porous surface. We aim at validating the porous media models commonly used in CFD with our previous experimental PIV work in idealized geometries treated with FDS. We use FDS geometries from Synchrotron micro-tomography of the deployed stents to build "high-fidelity" CFD simulations. Simpler simulations were run using a porous surface, whose properties were first taken from the literature. The resulting flow topologies were compared to the experimental observations and the porous model parameters were adjusted, based on the curvature of the parent vessel, to improve the accuracy of the modeled stent in the aneurysm hemodynamics.