Biomechanics of neck and head arteries: the development of aneurysms and the separation of atherosclerotic plaques with combined pathologies

The paper presents the results of modelling various variants of combined pathologies in the cerebral and carotid arteries. The main idea of the study was to create a prognostic model allowing to estimate the risks of aneurysm development in circle of Willis and atherosclerotic plaque detachment in the carotid arteries. Such a system may be useful to physicians in routine practice when planning treatment tactics in patients with combined arterial pathologies. The arterial system of the neck and head: sections of the common carotid artery (CCA), external carotid artery (ECA), internal carotid artery (ICA) and the vessels of the circle of Willis, including the anterior, middle and posterior cerebral arteries, the anterior communicating artery (ACA), the posterior communicating artery (PCA) and the basilar artery (BA). Based on the literature analysis, a number of pathologies of the cerebral and carotid arteries, most frequently occurring in various combinations, were identified: stenoses of the ICA and aplasia (absence) of one of the connecting arteries were considered from the point of view of geometrical features. In addition, the character of blood flow in the basilar artery, which can change its direction in steal-syndrome, was taken into account. Based on the analysis of mass blood flow and wall shear stress, two degrees of risk of aneurysm formation were distinguished. High risk corresponds to cases for which both of these values were statistically significantly different from the norm. Medium risk corresponds to cases for which only one of the values was statistically significantly different from the norm. For models containing atherosclerotic plaques, data on shear and normal stresses on the surfaces of atherosclerotic plaques were tabulated. The risk of plaque detachment on each side was determined for each case by analysing the result sets.