Parametric Characterization of the Hemodynamics Inside Cerebral Aneurysms Undergoing Flow Diverting Stent Therapy*

Flow-diverting stents (FDS) are often used to endovascularly treat cerebral aneurysms(CAs). They are designed to reduce shear stresses and increase residence times of blood flow in the aneurysm sac, promoting the development of a stable thrombus. Successful treatment is highly dependent on the degree that CA hemodynamics are altered following treatment. Here, we study the flow-field inside idealized CA models via 3D particle image velocimetry. A pulsatile flow-loop allows for the regulation of the pulsatile waveform before and after FDS treatment. By varying the waveform frequency, mean flow-rate, and curvature of the model’s parent-vessel, we explore the CA flow field across the entire physiological range of Reynolds number(Re), Dean number(De) and Womersely number(Wom). Results show that stresses due to flow entering the aneurysm, both on the vessel walls (Eulerian) and on the flowing platelets (Lagrangian), are reduced following treatment, but the reduction is minimal at high values of De. The sense of rotation of the primary aneurysmal sac vortex is also highly dependent on De and Wom. This parametric characterization of the aneurysm flow-field will help establish a causal connection between the hemodynamics of FDS-treated CAs and clinical outcomes.