Effect of blood rheological propeties on the formation of recirculation zones behind of coronary artery stenosis

The present study is devoted to the investigation of the influence of blood rheological properties on the features of recirculation zone formation in hemodynamic flows near coronary artery stenosis. The Newtonian model and the Carreau model were used to describe the dynamic viscosity. Calculations were performed for an ideal 2D vessel with double and single stenosis, each of which had a degree of overlap of 50–80 %, and for a 3D model of a real coronary artery with a stenosis of 50 %, which was reconstructed from X-ray data. On the example of 2D vessel model the formation of recirculation zones after stenosis was theoretically substantiated by methods of mathematical and computer modeling. The formation of stationary vortex regions significantly depended on the blood model used. The relationship between the characteristics of the blood flow recirculation phenomenon and local and general hemodynamic characteristics is shown. To demonstrate the relationship between the rheological properties of blood and the characteristics of the phenomenon of blood flow recirculation on more complex vessel geometries, similar computer calculations were performed for a three-dimensional model of a real coronary artery. Comparative analysis of the Newtonian model and the Carro model showed that the non-Newtonian behavior of blood significantly affects such hemodynamic characteristics of blood flow as viscosity, pressure, shear stress and shear rate. A significant difference in the obtained results is shown in the case of high flow velocities. It was concluded that the Newtonian blood model can be used only in vessels with minimal disturbances in the blood flow pattern.