Investigating arterial geometry risk factors for carotid artherosclerotic disease

The breadth in patient demographics exhibiting carotid artery disease is not explained by traditional vascular risk factors (such as smoking). A recent clinical study of a cross-section of high risk factor patients undergoing Computed Tomography (CT) angiography has linked aspects of carotid geometry, namely bifurcation angle and internal carotid artery (ICA) diameter, to the pathogenesis of ICA stenosis. Large ICA angle and small radius are implicated as potential risk factors. Abnormal wall shear stress has been found for ICA angles greater than 25?. These patient-specific factors together with traditional factors may aid the early identification of patients at high risk of developing carotid artherosclerosis requiring surgical intervention. Here, we test the hypothesis of that study using flow simulations in a real, clinical carotid geometry. The meshless method, Smoothed Particle Hydrodynamics, is used to simulate blood flow through the carotid bifurcation. We assume the flow to be Newtonian and pulsatile and the walls to be rigid. The resulting flow field and arterial wall shear stresses are investigated for a range of carotid geometry variants where the bifurcation angle is artificially modified from the original clinical model. Finally we investigate the interaction between time-varying flow and different outflow pressure boundary conditions and how these influence arterial flow and wall stresses.