Experimental and numerical investigation of hemodynamics in double-wall flow-diversion stents for intracranial aneurysm.

Flow diversion stents are used to treat intercranial aneurysms (IA) by redirecting blood flow away from the aneurysm sac, promoting intra-aneurysmal thrombosis and vessel wall remodeling by reducing wall shear stresses in the IA. This study experimentally and numerically evaluates the hemodynamic performance of a newly developed double-wall flow diversion stent. A two-dimensional clear epoxy resin model of an idealized saccular aneurysm (dome diameter: 9.7 mm; neck width: 10 mm) was fabricated. A peristaltic pump is used to maintain a flow rate of 200 ml/min (Re_avg = 758). Velocity fields were measured using a PIV system with a 532 nm Nd: YAG laser (30 mJ/pulse, 10 kHz) and a high-speed camera (1280 × 800 pixels, 20 µm resolution) capturing 60 image pairs per second. Numerical simulations were performed using ANSYS Fluent and SimVascular, an open source stabilized finite element solver and validated against the PIV measurements. Subsequently, three-dimensional cerebral aneurysm models with and without stents were simulated to assess the effect of stent porosity, defined as the ratio of open area to total surface area on post-treatment hemodynamics. Physiological pulsatile flow is prescribed at the inlet, while the outlet is modeled using a resistance boundary condition. Preliminary results suggest the experimental stent reduces flow recirculation by 48.3% and reduces wall shear stress inside the dome by 55.8%.