Key result
Larger vertebral artery bifurcation diameter is linked to lower wall shear stress and endothelial dysfunction risk.
Why the study?
The mechanics of vertebral artery stenosis from a hemodynamic perspective, particularly the effect of bifurcation diameter, remains unclear.
Computational fluid dynamics simulations suggest that larger bifurcation diameters at the vertebral artery origin are associated with lower wall shear stress, potentially increasing the risk of atherosclerosis.
Hypothesis-generating for vertebral geometry in atherosclerosis; human validation required before clinical consideration.
The stenosis at the beginning segment of the vertebral artery accounts for the first risk of stroke in the posterior circulation. The extracranial vertebral arteries, especially the proximal ends, have been considered to be the predilection sites of stenosis or occlusion. From the perspective of hemodynamics, the mechanics of vertebral arteries stenosis is still unclear. In this paper, the formation of atherosclerosis in proximal end was concerned from the aspects of the effect of bifurcation diameter. Different models represent different bifurcation diameter. In order to find correlation between bifurcation diameter and WSS we build different models. Three idealized models with the vertebral artery diameter of [Formula: see text][Formula: see text]m (Model A1), [Formula: see text][Formula: see text]m (Model A2) and [Formula: see text][Formula: see text]m (Model A3) respectively and seven realistic models were analyzed by using computational fluid dynamics tools. The area of low wall shear stress (WSS, [Formula: see text] 1.5[Formula: see text]Pa) in the proximal end of vertebral artery extracted at the peak systole in the idealized models were 2.25[Formula: see text]e-7, 8.55[Formula: see text]e-7 and 1.61[Formula: see text]e-6[Formula: see text]m2, respectively. The area of low WSS on the vertebral artery origin of realistic models extracted at the peak systole were 0, 1.18[Formula: see text]e-09, 3.91[Formula: see text]e-07, 1.68[Formula: see text]e-07, 5.46[Formula: see text]e-06, 1.16[Formula: see text]e-06 and 2.25[Formula: see text]e-06[Formula: see text]m2, respectively. Moreover, the time-averaged WSSs of the three idealized models were 3.95, 3.56 and 3.19, respectively. The time-averaged WSSs of the realistic models were 6.28, 6.36, 4.48, 4.71, 3.59, 3.59 and 3.31[Formula: see text]Pa, respectively. With the increase of bifurcation diameter, the risk of endothelial dysfunction increases, and the same is to intimal hyperplasia.
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Ren et al. (2016) studied Vertebral artery origin stenosis (n=10). Bifurcation diameter vs. Different bifurcation diameters was evaluated on Area of low wall shear stress (WSS) and time-averaged WSS. Increased bifurcation diameter of the vertebral artery is associated with a larger area of low wall shear stress and lower time-averaged wall shear stress, increasing the risk of endothelial dysfunction.
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