Numerical investigation of hemodynamic performance of a stent in the main branch of a coronary artery bifurcation.

Introduction: The effect of a bare-metal stent on the hemodynamics in the main branch of a coronary artery bifurcation with a particular type of stenosis was numerically investigated by the computational fluid dynamics (CFD). Methods: Three-dimensional idealized geometry of bifurcation was constructed in Catia modelling commercial software package. The Newtonian blood flow was assumed to be incompressible and laminar. CFD was utilized to calculate the shear stress and blood pressure distributions on the wall of main branch. In order to do the numerical simulations, a commercial software package named as COMSOL Multiphysics 5.3 was employed. Two types of stent , namely, one-part stent and two-part stent were applied to prevent the build-up and progression of the atherosclerotic plaques in the main branch. Results: A particular type of stenosis in the main branch was considered in this research. It occurred before and after the side branch. Moreover, it was found that the main branch with an inserted one-part stent had the smallest region with the wall shear stress (WSS) below 0.5 Pa which was the minimum WSS in the main branch without the stenosis. Conclusion: The use of a one-part stent in the main branch of a coronary artery bifurcation for the aforementioned type of stenosis is recommended.

Numerical investigation of the blood flow through the middle cerebral artery.

Introduction: The middle cerebral artery (MCA) is one of the three major paired arteries that supply the blood to the cerebrum. In the present study, the three-dimensional (3D) blood flow in the left MCA was numerically simulated by using the medical imaging. Methods: The arterial geometry was obtained by applying the CT angiography of the MCA of a 75-year-old man. The blood flow was assumed to be laminar and unsteady. Numerical simulations were done by commercial software package COMSOL Multiphysics 5.2. In this software, the Galerkin's finite element method was applied to solve the governing equations. Results: It was found that the results obtained for the Newtonian and non-Newtonian models of blood do not differ from each other significantly. Thus, the Newtonian model for blood flow in the MCA is acceptable. Also, the most susceptible region of the MCA for Atherosclerosis was detected. Conclusion: It can be concluded that the application of the Newtonian model for the blood flowing in the MCA is acceptable. Also, atherosclerosis has the potential to occur at the middle of a branch of the MCA which has the highest geometrical curvature.