Fluid Structure Interaction Study of Stenosed Carotid Artery Considering the Effects of Blood Pressure and Altered Gravity

Abstract

Atherosclerosis is a very common cardiovascular disease (CVD) causing increased morbidity. Atherosclerosis is a disease that involves several factors and usually affects the wall of the arterial bifurcations. Advanced Computational Fluid Dynamics (CFD) techniques has the potential to shed more light in understanding of the causes of atherosclerosis and perhaps in its early diagnosis. Fluid Structure Interaction (FSI) study was carried out on two different three dimensional patient specific cases (a) Normal carotid bifurcation and (b) Stenosed carotid bifurcation. Physiological conditions were considered to evaluate hemodynamic parameters and understand the origin and progression of atherosclerosis in the carotid artery bifurcation, first for the normal and then with hypertension disease. Commercial software ANSYS and ANSYS CFX (version 19.0) was used to perform a two-way FSI using a fully implicit second-order backward Euler differencing scheme. Arterial response was calculated by employing an Arbitrary Lagrangian-Eulerian (ALE) formulation and using the temporal blood response. The carotid artery bifurcation caused a velocity reduction and backflow was observed causing a reduction in the shear stress. A low shear stress resulted due to an oscillatory behavior at the start point of the internal carotid artery near the carotid sinus. Shear stresses are obtained by using anatomically realistic 3D geometry and representative physiological conditions. Results of this study agree with those in the literature showing that the regions with low wall shear stress. Geometry and flow conditions greatly affected the hemodynamics of the carotid artery. Furthermore, regions of relatively low wall shear stress were observed post stenosis, which is a known cause of plaque development and progression. Under altered gravity conditions the same artery was studied to determine the flow conditions and predict the progression of plague.