The impact of Various Configurations of Circle of Willis and Variations of Internal Carotid Artery on Ischemic Stroke and Plaque Rupture: CFD Study

Various configurations of Circle of Willis (COW) accompanied by stenosis in the internal carotid artery (ICA) may be associated with intense impairment of blood perfusion, which leads to ischemia. Furthermore, plaque rupture/erosion is another risk driven by the occurrence of atherosclerosis which is highly dependent on artery upstream and resultant shear stress exerted tangentially on vessel walls. It can occur even in moderate stenosis, which is not likely to experience ischemia. In the first part of this study, the impact of various configurations of COW on the risk of ischemia was investigated. Fractional pressure ratio (FPR), which represents functional severity of stenosis, was computed from steady computational simulations with boundary conditions tuned to replicate the physiological systolic pressure and flow through arteries among models. The second part studied the impact of variations of ICA on the risk of plaque rupture with a similar Computational procedure. Results of the first part of the study highlighted the significant impact of COW variations on flow perfusion in cerebral arteries, indicating that compensation of blood flow decreased with the incompleteness of COW. The COW lacking the anterior communicating artery (ACoA) was identified as the most critical case, with the lowest FPR of ۰.۶۷۰. The second part compared the typical variations of ICA and identified the V and C-shaped ICA more prone to plaque rupture/erosion by evaluating the wall shear stress and wall shear stress gradient. In conclusion, as to the risk of ischemia, COW without ACoA should be paid more attention due to the noticeable low FPR. With respect to the risk of plaque rupture for ICA, C and V-shaped ones are at higher risk, suggesting that the role of the curvature and nonplanarity of affected stenotic segments should be regarded as factors determining the possible plaque rupture

Keywords:

Hemodynamics , Intracranial arterial stenosis (ICAS) , Computational fluid dynamics , Stroke