Hemodynamic Effect of Flow Diverter and Coils in Treatment of Large and Giant Intracranial Aneurysms

Abstract

This study aimed to investigate the hemodynamic changes induced by a flow diverter (FD) and coils in the treatment of internal carotid artery aneurysms, as well as to evaluate the effect of this treatment by using angiographic follow-up data. Six large and giant aneurysms were treated by the Tubridge FD and loose packing coils between June 2013 and May 2015. Patient-specific models were constructed and analyzed using a computational fluid dynamics (CFD) method. The virtual FD deployment method was used to implant the Tubridge stent into a 3-dimensional digital subtraction angiographic image of the aneurysms, and the coils were simulated by a porous medium model. Tubridge FD alone can significantly reduce the intra-aneurysmal flow velocity (0.17 ± 0.05 m/s-0.11 ± 0.06 m/s, P < 0.001) and wall shear stress (WSS, 1.39 ± 0.29 Pa-0.77 ± 0.34 Pa, P= 0.001) and increase the low wall shear area (LSA, 6.38% ± 1.49%-34.60% ± 28.90%, P= 0.047). Coils, as a supplementary measure, further reduced the velocity (0.11 ± 0.06 m/s-0.08 ± 0.05 m/s, P= 0.03) and WSS (0.77 ± 0.34 Pa-0.47 ± 0.35 Pa, P= 0.04) and increased the LSA (34.60% ± 28.90%-63.33% ± 34.82%, P= 0.044). Aneurysm with sustained strong inflow after treatment (case 3, 25% reduction in velocity, 12% reduction in WSS, and 16% increment in LSA) showed partial patency, whereas others with a weaker inflow jet (mean 56% reduction in velocity, 74% reduction in WSS, and 1081% increment in LSA) showed complete occlusion at follow-up. On the basis of using the CFD method, adjunctive coiling with the Tubridge FD placement may significantly reduce intra-aneurysmal flow velocity and WSS, promoting thrombosis formation and occlusion of aneurysms.