Combined Effects of Flow Diverting Strategies and Parent Artery Curvature on Aneurysmal Hemodynamics: A CFD Study

Abstract

PurposeFlow diverters (FD) are increasingly being considered for treating large or giant wide-neck aneurysms. Clinical outcome is highly variable and depends on the type of aneurysm, the flow diverting device and treatment strategies. The objective of this study was to analyze the effect of different flow diverting strategies together with parent artery curvature variations on altering intra-aneurysmal hemodynamics.MethodsFour ideal intracranial aneurysm models with different parent artery curvature were constructed. Computational fluid dynamics (CFD) simulations of the hemodynamics before and after applying five types of flow diverting strategies (single FD, single FD with 5% and 10% packing density of coils, two FDs with 25% and 50% overlapping rate) were performed. Changes in pressure, wall shear stress (WSS), relative residence time (RRT), inflow velocity and inflow volume rate were calculated and compared.ResultsEach flow diverting strategy resulted in enhancement of RRT and reduction of normalized mean WSS, inflow volume rate and inflow velocity in various levels. Among them, 50% overlapped FD induced most effective hemodynamic changes in RRT and inflow volume rate. The mean pressure only slightly decreased after treatment. Regardless of the kind of implantation of FD, the mean pressure, inflow volume rate and inflow velocity increased and the RRT decreased as the curvature of the parent artery increased.ConclusionsOf all flow diverting strategies, overlapping FDs induced most favorable hemodynamic changes. Hemodynamics alterations post treatment were substantially influenced by parent artery curvature. Our results indicate the need of an individualized flow diverting strategy that is tailored for a specific aneurysm.

Closed-Cell Stent-Assisted Coiling of Intracranial Aneurysms: Evaluation of Changes in Vascular Geometry Using Digital Subtraction Angiography

“…Hemodynamic factors play an important role in the pathogenesis, progression, and rupture of cerebral aneurysms and are especially sensitive to variations in vessel geometry [ 16 , 19 – 21 ]. A previous study that used ideal intracranial aneurysm models found a strong dependence of aneurysm hemodynamics on the curvature of the parent artery; the straighter the parent vessel, the smaller the pressure, inflow volume rate and inflow velocity in the aneurysm [ 16 ].…”

“…Zenteno et al attributed this therapeutic effect to the straightening of the vessel-aneurysm complex induced by balloon inflation during balloon-mounted stent deployment [ 11 , 13 ]. Results of computational flow and ideal aneurysm model analysis also suggest that the straightening of the parent vessel is associated with a favorable outcome [ 16 , 17 ], as it leads to smaller pressure, inflow volume rate and inflow velocity in the aneurysm [ 16 , 18 ]. To investigate the effect of closed-cell stent remodeling in real patients in a clinical setting, we measured structural changes of the vessel–aneurysm complex of bifurcation and sidewall aneurysms treated at our institution.…”

The relationship between plasma viscosity and endotel markers in patients with ascending aortic aneurysms: a pilot study

“…To the best of our knowledge, this study represents the first published research to show a possible association between PV and AsAA development by demonstrating a significantly increased PV in untreated AsAA patients compared with controls. Variations in aneurysmal geometry and the prop-erties of a flow diverter are among many determinants of aneurysmal hemodynamics [16]. Altered vessel diameter impedes microcirculation with subsequent impairment of capillary perfusion [7,17].…”

Effects of size and elasticity on the relation between flow velocity and wall shear stress in side-wall aneurysms: A lattice Boltzmann-based computer simulation study

“…Intra-aneurysm (IA) hemodynamics is sensitive to morphological factors such as shape and size of the aneurysm [16][17][18][19]. It has been reported that an increase of aneurysm size leads to a decrease of the average IA flow velocity, U , and wall shear stress, s w , in the case of side-walltype aneurysms [20,21].…”