Hemodynamic Investigation of the Effectiveness of a Two Overlapping Flow Diverter Configuration for Cerebral Aneurysm Treatment

Abstract

Flow diverters (FDs) are widely employed as endovascular treatment devices for large or wide-neck cerebral aneurysms. Occasionally, overlapped FDs are deployed to enhance the flow diversion effect. In this study, we investigated the hemodynamics of overlapping FDs via computational fluid dynamics (CFD) simulations. We reproduced the arterial geometry of a patient who had experienced the deployment of two overlapping FDs. We utilized two stent patterns, namely the patterns for one FD and two overlapping FDs. We calculated the velocity, mass flow rate, wall shear stress, and pressure loss coefficient as well as their change rates for each pattern relative to the no-FD pattern results. The CFD simulation results indicated that the characteristics of the blood flow inside the aneurysm were minimally affected by the deployment of a single FD; in contrast, the overlapping FD pattern results revealed significant changes in the flow. Further, the velocity at an inspection plane within the aneurysm sac decreased by up to 92.2% and 31.0% in the cases of the overlapping and single FD patterns, respectively, relative to the no-FD pattern. The simulations successfully reproduced the hemodynamics, and the qualitative and quantitative investigations are meaningful with regard to the clinical outcomes of overlapped FD deployment.

Efficacy and safety of flow diverter combined with coil embolization and evidence-based antithrombotic regimen in the treatment of ruptured aneurysms

“…24 Multiple FDs may furthermore exert a flow-diverting effect to lower blood flow and pressure within the aneurysm. 25 However, increased metal coverage in multiple FDs also indicates a higher prevalence of perioperative ischemic events due to activation of the blood coagulation system by the devices' coating, 26 and FD overlapping may raise the risk of restenosis or occlusion of the parent artery in the long term. Covered stents are more effective than FD in blocking blood flow into the aneurysm and occluding the lesion.…”

De novo expansion formation in the outer curvature of the internal carotid artery after flow diverter deployment for an infectious cavernous carotid aneurysm: illustrative case

“…The overlapping of 2 flow diverters is expected to increase the metal coverage of the aneurysm neck and improve the occlusion rate. 11 In this case, it might have been better to deploy 2 overlapping flow diverters in the outer curvature of the artery. It was an infectious aneurysm with a fragile vessel wall, and parent artery occlusion is still considered an option.…”

CFD Study of the Effect of the Angle Pattern on Iliac Vein Compression Syndrome

“…The model comprised approximately 1.7 million elements, with an element size of approximately 12 μm. With this mesh density, mesh convergence was achieved [ 32 ].…”

“…To calculate flow fields and hemodynamic parameters, blood flow in the iliac veins assumed incompressible Newtonian flow [ 25 ]. Values for blood fluid density and dynamic viscosity (1050 kg/m 3 and 0.003 kg/m/s, respectively) were used according to previous studies [ 32 , 33 , 34 , 35 ]. As in previous CFD analyses, the model assumed venous wall rigidity [ 34 ].…”