Influence of the internal carotid arteries stenosis on the hemodynamics of the circle of Willis communicating arteries: a numerical study

Modern authors argue that carotid arteries stenosis leads to changes in circle of Willis blood flow, which may contribute to aneurysm formation. It was found that up to 3.2 % of patients with carotid arteries stenosis have associated cerebral aneurysms. Moreover, it is known that performing a surgical intervention to remove carotid stenoses can lead to a decrease in cerebral aneurysm size or their complete disappearance. In this regard, the problem arises of studying effect of the carotid arteries stenosis on human brain vessels aneurysms development. In this work, a biomechanical study of the anterior communicating and posterior communicating arteries hemodynamics for various variants of the circle of Willis structure in combination with atherosclerotic plaques of carotid arteries was carried out. Based on computed angiography data, 45 models of the circle of Willis and carotid arteries with various degrees of stenosis and localization of atherosclerotic plaques were constructed and analyzed. Numerical modeling of the unsteady blood flow in the circle of Willis and carotid arteries was performed in Ansys CFX. Wall shear stress of the anterior and posterior communicating arteries were analyzed, as well as mass blood flows along these arteries. The influence of the carotid arteries stenosis degree, as well as their combination with anomalies in the circle of Willis on change in wall shear stresses and mass blood flows in communicating arteries, was evaluated. The most dangerous combinations of the carotid arteries stenosis and types of the cerebral arterial circle which increase the risk of developing communicating arteries aneurysms were identified.