Flow pattern analysis in a highly stenotic patient-specific carotid bifurcation model using a turbulence model

Abstract

The aim of this study is to investigate the blood flow pattern in carotid bifurcation with a high degree of luminal stenosis, combining in vivo magnetic resonance imaging (MRI) and computational fluid dynamics (CFD). A newly developed two-equation transitional model was employed to evaluate wall shear stress (WSS) distribution and pressure drop across the stenosis, which are closely related to plaque vulnerability. A patient with an 80% left carotid stenosis was imaged using high resolution MRI, from which a patient-specific geometry was reconstructed and flow boundary conditions were acquired for CFD simulation. A transitional model was implemented to investigate the flow velocity and WSS distribution in the patient-specific model. The peak time-averaged WSS value of approximately 73 Pa was predicted by the transitional flow model, and the regions of high WSS occurred at the throat of the stenosis. High oscillatory shear index values up to 0.50 were present in a helical flow pattern from the outer wall of the internal carotid artery immediately after the throat. This study shows the potential suitability of a transitional turbulent flow model in capturing the flow phenomena in severely stenosed carotid arteries using patient-specific MRI data and provides the basis for further investigation of the links between haemodynamic variables and plaque vulnerability. It may be useful in the future for risk assessment of patients with carotid disease.

Subject-Specific Fully-Coupled and One-Way Fluid-Structure Interaction Models for Modeling of Carotid Atherosclerotic Plaques in Humans

“…Results showed that the flow velocity increased when passing through a region of stenosis, and the maximum velocity was located at the throat of the plaque, which is in agreement with previous studies [ 24 , 34 ]. According to the Bernoulli principle, increased blood velocity across the lumen reduces the lateral blood pressure acting on the plaque.…”

Hemodynamics in Transplant Renal Artery Stenosis and its Alteration after Stent Implantation Based on a Patient-specific Computational Fluid Dynamics Model

“…It is reported that distal region of stenotic artery is more prone to develop atherosclerosis. [25] Multiple stenosis usually occurred at the downstream of a diseased vascular bed due to low WSS area distal to the primary stenosis. [26] The possible mechanism is that low WSS can influence the development of neointimal hyperplasia and lead to stenosis by triggering inflammatory cell-mediated destructive remodeling.…”

Computational analysis to predict the effect of pre-bifurcation stenosis on the hemodynamics of the internal and external carotid arteries

“…In terms of stenosis of carotid arteries, a specific risk is that of stroke due to insufficient blood supply to brain [6,7]. Furthermore, vascular stenosis is associated with perturbed blood flow patterns and altered wall shear stress [8,9]. Therefore, there has been much focus on understanding vascular plaque formation and predicting the effects of stenosis on hemodynamics [10][11][12].…”

“…One such approach is to use numerical models to calculate blood flow [13]. As blood flow through the circulatory system is pulsatile, computational studies use transient models [8,14,15]. Computational fluid dynamics (CFD) models in particular are useful because to study either static or transient blood flow, where three-dimensional models can be generated from medical images.…”