FLOW PATTERNS AND WALL SHEAR STRESS DISTRIBUTION IN HUMAN VERTEBROBASILAR SYSTEM: A COMPUTATIONAL STUDY TO INVESTIGATE SMOKING EFFECTS ON ATHEROSCLEROTIC STENOSIS AT DIFFERENT AGES

The blockage of arteries in the human vertebrobasilar system (VBS) usually results in major disability or death. It has been widely seen that atherosclerotic stenosis occurs at locations with a low wall shear stress or a high oscillatory shear index. This study investigates the potential of developing arteriostenosis due to smoking in the human VBS at 3 different ages. For this purpose, the VBS has been modeled for smoking/nonsmoking subjects that are 20, 50, and 70 years of age. The governing equations were discretized and solved by a finite volume-based software (ANSYS Fluent v15.0). Five potential locations for stenosis were determined along the VBS. The quantified risks of stenosis were found for smoking and nonsmoking groups, indicating that the locations prone to stenosis are at a higher risk in smoking subjects. The stenosis probability increases around vertebrobasilar junction point (VBJ) and along the right vertebral artery in the 50 and 70-year-old smoker subjects, respectively. Also, the results suggested that the area around the VBJ is at higher risk levels for stenosis at different ages for both smoking and nonsmoking subjects.