Realistic non-Newtonian viscosity modelling highlights hemodynamic differences between intracranial aneurysms with and without surface blebs

Abstract Most computational fluid dynamic (CFD) simulations of aneurysm hemodynamics assume constant (Newtonian) viscosity, even though blood demonstrates shear-thinning (non-Newtonian) behavior. We sought to evaluate the effect of this simplifying assumption on hemodynamic forces within cerebral an...

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Bibliographic Details
Published in:Journal of biomechanics 2014-11, Vol.47 (15), p.3695-3703
Main Authors: Hippelheuser, James E, Lauric, Alexandra, Cohen, Alex D, Malek, Adel M
Format: Article
Language:English
Subjects:
Aged
Aneurysms
Angiography
Blebs
Blister
Blood
Blood Viscosity
Computational fluid dynamics
Computer simulation
Domes
Fluid dynamics
Hemodynamics
Humans
Intracranial Aneurysm - blood
Intracranial aneurysms
Mathematical models
Medical imaging
Middle Aged
Models, Biological
Newtonian
Non-Newtonian fluid
Physical Medicine and Rehabilitation
Risk
Shear stress
Stress, Mechanical
Veins & arteries
Viscosity
Wall shear stress
Wall shear stresses
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Summary:Abstract Most computational fluid dynamic (CFD) simulations of aneurysm hemodynamics assume constant (Newtonian) viscosity, even though blood demonstrates shear-thinning (non-Newtonian) behavior. We sought to evaluate the effect of this simplifying assumption on hemodynamic forces within cerebral aneurysms, especially in regions of low wall shear stress, which are associated with rupture. CFD analysis was performed for both viscosity models using 3D rotational angiography volumes obtained for 26 sidewall aneurysms (12 with blebs, 12 ruptured), and parametric models incorporating blebs at different locations (inflow/outflow zone). Mean and lowest 5% values of time averaged wall shear stress (TAWSS) computed over the dome were compared using Wilcoxon rank-sum test. Newtonian modeling not only resulted in higher aneurysmal TAWSS, specifically in areas of low flow and blebs, but also showed no difference between aneurysms with or without blebs. In contrast, for non-Newtonian analysis, bleb-bearing aneurysms showed significantly lower 5% TAWSS compared to those without ( p =0.005), despite no significant difference in mean dome TAWSS ( p =0.32). Non-Newtonian modeling also accentuated the differences in dome TAWSS between ruptured and unruptured aneurysms ( p
ISSN:0021-9290
1873-2380
DOI:10.1016/j.jbiomech.2014.09.027