Carotid geometry effects on blood flow and on risk for vascular disease
Kien T Nguyen1, Christopher D Clark, Thomas J Chancellor
1School of Chemical, Biological and Materials Engineering, The University of Oklahoma, 100 East Boyd, SEC T-335, Norman, OK 73019, USA.
Insights
Atherosclerosis risk increases with specific carotid artery geometry. Larger bifurcation angles and certain off-plane angles lower wall shear stress, promoting plaque buildup and increasing vascular disease risk.
Area of Science:
- Biomedical Engineering
- Fluid Dynamics
- Cardiovascular Science
Background:
- Atherosclerotic diseases manifest at sites with complex hemodynamics, like artery bifurcations.
- These regions are characterized by low or oscillatory wall shear stress (WSS).
Purpose of the Study:
- To simulate 3D pulsatile blood flow in a carotid artery bifurcation model.
- To quantify atherogenesis risk linked to various carotid artery geometries.
- To propose a risk scale based on average WSS for predicting vascular disease.
Main Methods:
- Utilized a finite volume numerical method for blood flow simulation.
- Analyzed the impact of bifurcation angle and out-of-plane angles on WSS.
- Developed a risk scale based on internal carotid artery sinus wall WSS.
Main Results:
- Larger internal carotid artery angles increase recirculation and lower sinus WSS, elevating plaque buildup risk.
- Off-plane angles decrease sinus WSS for angles >25 degrees, increasing risk.
- Symmetric bifurcations increase sinus WSS, reducing vascular disease risk.
Conclusions:
- Carotid artery geometry significantly influences hemodynamic WSS and atherogenesis risk.
- Bifurcation and off-plane angles are critical factors in predicting plaque formation.
- Understanding these geometric effects can aid in assessing and mitigating vascular disease risk.
Abstract:
It has been widely observed that atherosclerotic diseases occur at sites with complex hemodynamics, such as artery bifurcations, junctions, and regions of high curvature. These regions usually have very low or highly oscillatory wall shear stress (WSS). In the present work, 3D pulsatile blood flow through a model of the carotid artery bifurcation was simulated using a finite volume numerical method. The goal was to quantify the risk of atherogenesis associated with different carotid artery geometries. A risk scale based on the average WSS on the sinus wall of the internal carotid artery was proposed-a scale that can be used to quantify the effect of the carotid geometry on the relative risk for developing vascular disease. It was found that the bifurcation angle and the out-of-plane angle of the internal carotid artery affect the formation of low stress regions on the carotid walls. The main conclusions are: (a) larger internal carotid artery angles (theta(IC)) generally increase the frequency and the area of blood recirculation and lower the WSS on the sinus wall, hence increasing the risk of plaque build-up; (b) off-plane angles were found to lower the WSS on the sinus for geometries with theta(IC)25 degrees . Larger off-plane angles generally increase the danger of plague build-up; (c) for theta(IC) < 25 degrees , the off-plane angle does not have an obvious effect on the hemodynamic WSS; (d) symmetric bifurcations were found to increase the WSS on the sinus wall and ease the risk of vascular disease.
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