In uence of ow diverters on the hemodynamic conditions of intracranial aneurysms: A CFD study

M. AGUILAR; I. LARRABIDE; J. MACHO; E. E. VIVAS; D. RUFENACHT; M.C. VILLA-URIOL; S. CITO; A. F. FRANGI

Hourton

Conferencia; Live Interventional Neuroradiology Conference (LINC) in conjunction with Intracranial Stent Meeting (ICS) 2010; 2010

Texas Heart Institute

Purpose Despite the wide availability of endovascular and surgical techniques, there are still some intracranial aneurysms that remain too complex to undergo such procedures. Low-porosity stents have been proposed recently as a therapeutic alternative for such aneurysms. The purpose of this study is to assess the changes in the hemodynamic conditions on aneurysms with different morphology before and after treatment with flow diverters, using computational fluid dynamics (CFD).Materials Two patient-specific vascular models, each harboring a single aneurysm, were selected to evaluate the effect of the SILK stent (Balt Extrusion, Montmorency, France) on the intra-aneurysmal flow. One patient presented a wide-necked aneurysm (AR= 1.19) at the anterior choroidal segment; the other, a narrow-necked one (AR= 2.31) at the posterior communicating segment. Methods Using the @neurIST complex information tool chain, vascular models were reconstructed from the available medical images. The stent was virtually implanted so as to ensure its proper apposition using the Fast Virtual Stenting method. Volumetric meshes were generated using ICEM-CFD (Ansys Inc., Canonsburg, PA). Walls were set to be rigid with no-slip boundary condition and blood was considered as a Newtonian fluid. Mass flow rate at the inlet and pressure at the outlets were imposed as boundary conditions (following @neurIST data analysis protocol). Simulations were carried out in ANSYS-CFX, to estimate shear stress at the aneurysmal wall and inflow at the aneurysm neck.  Results The post-treatment reduction of flow into the wide-necked aneurysm was 9.2% at peak systole and 58.1% time-averaged over the cardiac cycle. The reduction in average shear stress on the aneurysm wall was 57.6% and 83.3%, respectively. The narrow-necked aneurysm showed a general increase in the reduction for each parameter; inflow at the neck was reduced by 37.3% and 64.7%, respectively and shear stress by 65.6% and 83.6%, respectively. Conclusions CFD simulations can be employed to estimate the reduction of flow into the aneurysm due to the placement of a flow diverter. It was observed that the flow diverter was able to disrupt high-velocity flow entering the aneurysm and redirect it through the parent vessel.