The hemodynamic effects of in-tandem carotid artery stenosis: implications for carotid endarterectomy
Zhi-Yong Li1, Valentina Taviani, Tjun Tang
1University Department of Radiology, Cambridge University Hospitals National Health Service Foundation Trust, United Kingdom. ZYL22@cam.ac.uk
Insights
Computational fluid dynamics (CFD) modeling of tandem internal carotid artery stenosis suggests that upstream plaque size influences downstream hemodynamics. Carotid endarterectomy (CEA) decisions require considering lesion geometry and position for optimal patient outcomes.
Area of Science:
- Biomedical Engineering
- Cardiovascular Research
- Medical Imaging and Simulation
Background:
- The clinical benefit of carotid endarterectomy (CEA) for severe internal carotid artery stenosis with a downstream lesion remains debated.
- Understanding the hemodynamic impact of tandem internal carotid artery stenosis is crucial for surgical decision-making.
Purpose of the Study:
- To simulate the hemodynamic and wall shear stress (WSS) effects of in-tandem internal carotid artery stenosis using computational fluid dynamics (CFD).
- To investigate how CEA might affect downstream stenotic lesions.
Main Methods:
- A CFD model simulating steady, viscous blood flow in a rigid tube with two asymmetric stenoses was developed.
- The study analyzed the effects of varying stenosis distance, upstream stenosis severity, and relative lesion positions on pressure and WSS.
Main Results:
- Plaque distance had minimal hemodynamic influence, except for a low WSS zone between closely spaced lesions (<4 arterial diameters).
- An upstream stenosis larger than the downstream one offered a protective hemodynamic effect.
- Lesion position influenced WSS but not pressure distribution.
Conclusions:
- Tandem stenosis geometry and position significantly impact hemodynamic effects, particularly WSS.
- Low WSS between lesions may promote plaque merging and endothelial dysfunction.
- CFD can aid risk stratification and inform CEA decisions for patients with in-tandem carotid stenosis.
Objectives:
It remains controversial whether patients with severe disease of the internal carotid artery and a coexisting stenotic lesion downstream would benefit from a carotid endarterectomy (CEA) of the proximal lesion. The aim of this study was to simulate the hemodynamic and wall shear effects of in-tandem internal carotid artery stenosis using a computational fluid dynamic (CFD) idealized model to give insight into the possible consequences of CEA on these lesions.
Methods:
A CFD model of steady viscous flow in a rigid tube with two asymmetric stenoses was introduced to simulate blood flow in arteries with multiple constrictions. The effect of varying the distance between the two stenoses, and the severity of the upstream stenosis on the pressure and wall shear stress (WSS) distributions on the second plaque, was investigated. The influence of the relative positions of the two stenoses was also assessed.
Results:
The distance between the plaques was found to have minimal influence on the overall hemodynamic effect except for the presence of a zone of low WSS (range -20 to 30 dyne/cm2) adjacent to both lesions when the two stenoses were sufficiently close (<4 times the arterial diameter). The upstream stenosis was protective if it was larger than the downstream stenosis. The relative positions of the stenoses were found to influence the WSS but not the pressure distribution.
Conclusions:
The geometry and positions of the lesions need to be considered when considering the hemodynamic effects of an in-tandem stenosis. Low WSS is thought to cause endothelial dysfunction and initiate atheroma formation. The fact that there was a flow recirculation zone with low WSS in between the two stenoses may demonstrate how two closely positioned plaques may merge into one larger lesion. Decision making for CEA may need to take into account the hemodynamic situation when an in-tandem stenosis is found. CFD may aid in the risk stratification of patients with this problem.