Key result
Conventional parabolic models underestimate carotid stenosis wall shear stress by ~60% due to plateau-shaped flow.
Why the study?
Due to a lack of flow field measurements in carotid stenosis vessels, commonly assumed velocity distribution forms in numerical simulations can cause wall shear stress estimates to differ by more than 40%.
Effect estimate: nearly 60% lower
Absolute Event Rate: 20.35% vs 7.25%
In a 3D printed model of carotid stenosis, blood velocity distribution was plateau-shaped rather than parabolic, suggesting traditional parabolic assumptions significantly underestimate wall shear stress.
Challenges parabolic assumptions for wall shear stress in carotid stenosis; hypothesis-generating for refined models pending validation.
BackgroundAtherosclerosis is an important cause of cardiovascular disease. The wall shear stress (WSS) is one of the key factors of plaque formation and dislodgement. Currently, WSS estimation is based on measurement of the blood velocity gradient. However, due to the lack of flow field measurements in carotid stenosis vessels, the two distribution forms (parabolic and non-parabolic) commonly considered in numerical simulations could cause WSS estimates to differ by more than 40%, which could seriously affect the accuracy of mechanical analysis. MethodsThis study was the first to apply 3D printing technology to create an experimental model of real-structure carotid arteries. Microparticle image velocimetry (micro-PIV) was adopted to comprehensively measure blood velocity field data at the stenosis location, providing experimental validation of numerical simulation (Fluent; finite volume method) results. Then, the flow field was simulated at a normal human heart rate (45-120 beats per minute). ResultsThis study revealed that when blood flowed across the carotid artery stenosis location, the velocity distribution was not parabolic but rather a plateau-shaped distribution, with a similar flow velocity in the central area (more than 65% of the total flow path). The WSS values calculated based on a parabolic velocity distribution and the maximum velocity were nearly 60% lower.ConclusionThis study provides a reliable method for WSS determination to better understand the vascular stenosis location and facilitate flow and shear force field research. In the future, it is necessary to carry out in-depth research on the relationship between the plaque shape, flow field distribution and WSS, and amendments to the calculated WSS for clinical stenosis should be proposed.
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Song et al. (2021) studied Carotid artery stenosis. Plateau-shaped velocity distribution (actual measurement) vs. Parabolic velocity distribution (conventional assumption) was evaluated on Wall shear stress (WSS) (nearly 60% lower). When blood flowed across the carotid artery stenosis location, the velocity distribution was plateau-shaped rather than parabolic, meaning wall shear stress values calculated using the conventional parabolic assumption were nearly 60% lower (7.25 Pa vs 20.35 Pa).
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