The Role of Hemodynamics in Intracranial Bifurcation Arteries after Aneurysm Treatment with Flow-Diverter Stents

NARATA, A.P.; DE MOURA, F.S.; LARRABIDE, I.; PERRAULT, C.M.; PATAT, F.; BIBI, R.; VELASCO, S.; JANUEL, A.-C.; COGNARD, C.; CHAPOT, R.; BOUAKAZ, A.; SENNOGA, C.A.; MARZO, A.

AMERICAN JOURNAL OF NEURORADIOLOGY

AMER SOC NEURORADIOLOGY

Año: 2017

0195-6108

BACKGROUND AND PURPOSE: Treatment of intracranial bifurcation aneurysms with flow-diverter stents can lead to caliber changes ofthe distal vessels in a subacute phase. This study aims to evaluate whether local anatomy and flow disruption induced by flow-diverterstents are associated with vessel caliber changes in intracranial bifurcations.MATERIALS AND METHODS: Radiologic images and demographic data were acquired for 25 patients with bifurcation aneurysms treatedwith flow-diverter stents. Whisker plots and Mann-Whitney rank sum tests were used to evaluate if anatomic data and caliber changescould be linked. Symmetry/asymmetry were defined as diameter ratio 1 ϭ symmetric and diameter ratio Ͻ1 ϭ asymmetric. Computationalfluid dynamics was performed on idealized and patient-specific anatomies to evaluate flow changes induced by flow-diverter stents in thejailed vessel.RESULTS: Statistical analysis identified a marked correspondence between asymmetric bifurcation and caliber change. Symmetry ratios werelower for cases showing narrowing or subacute occlusion (medium daughter vessel diameter ratio ϭ 0.59) compared with cases with posttreat-ment caliber conservation (medium daughter vessel diameter ratio ϭ 0.95). Computational fluid dynamics analysis in idealized and patient-specific anatomies showed that wall shear stress in the jailed vessel was more affected when flow-diverter stents were deployed in asymmetricbifurcations (diameter ratio Ͻ0.65) and less affected when deployed in symmetric anatomies (diameter ratio ϳ1.00).CONCLUSIONS: Anatomic data analysis showed statistically significant correspondence between caliber changes and bifurcation asym-metry characterized by diameter ratio Ͻ0.7 (P Ͻ .001). Similarly, computational fluid dynamics results showed the highest impact onhemodynamics when flow-diverter stents are deployed in asymmetric bifurcations (diameter ratio Ͻ0.65) with noticeable changes on wallsheer stress fields. Further research and clinical validation are necessary to identify all elements involved in vessel caliber changes afterflow-diverter stent procedures.