Statistical analysis of the association between rheological properties of blood and atherosclerosis

The aim of this study is to investigate the effects of non-Newtonian blood rheology models on the wall shear stress (WSS) distribution in a cohort of patients-specific coronary arteries. Twenty patients with diseased left anterior descending (LAD) coronary arteries (with varying degrees of stenosis severity from mild to severe) who underwent angiography and in-vivo pressure measurements were selected to perform computational fluid dynamics (CFD) simulations. Three-dimensional (3D) patient-specific geometries were reconstructed from 3D quantitative coronary angiography. To compare the effects of rheological properties of blood on WSS along the arteries, each artery was divided into 3 segments; proximal (pre-stenosis), stenosis and distal (post-stenosis). Blood was modelled as a Newtonian and non-Newtonian (Carreau-Yasuda, Casson and Power-law) fluid. Our findings showed that the WSS distributions over proximal and stenosis segments were significantly affected by the non-Newtonian properties of blood whereas the effect was negligible over distal segment. On the other hand, the type of non-Newtonian model is important to achieve accurate results over proximal and stenosis regions, but over distal region, it does not matter what model is used. Therefore, to simplify the simulation, the Newtonian model can be acceptable in finding the wall shear stress distribution over the distal region regardless of severity of stenosis.