Modeling blood flow through the carotid bifurcation

The carotid bifurcation, where the common carotid artery branches out into internal and external carotid arteries, is prone to the development of atherosclerosis and aneurysm. Samaee et al. investigated the hemodynamics of Newtonian and non-Newtonian blood flow within this region to better understand this heightened risk. They observed noticeable disparities between the two flow regimes, with more distinct differences near the junction site.

“Mechanical factors, such as low wall shear stress and recirculation flow, are extensively accepted as the markers of plaque formation and growth in the cardiovascular system,” said co-author Hadi Taghizadeh. “Since blood demonstrates many nonlinear features, Newtonian or non-Newtonian assumptions for the blood flow will affect these hemodynamic parameters in respective studies.”

First, the researchers fabricated a 3D silicone model of the carotid bifurcation using anatomical dimensions and relevant mechanical properties. Specific mixtures of water, glycerol, and xanthan gum were composed to act as Newtonian and non-Newtonian fluids with similar rheological properties to blood. Pressure/flow profiles were recorded in the bifurcation inlet/outlets and used in a fluid-solid interaction numerical simulations.

Velocity profiles of the non-Newtonian model were more flattened, with higher back flow during diastole. The shear stress waves, as well as shear-dependent parameters, also indicated significant differences for the two models. Regardless of flow regime, results showed good agreement with clinical outcomes in human carotid bifurcation. Near the bifurcation, marked fluctuations of shear stress are evident.

“Rheological assumptions for blood are important for clinical flow monitoring purposes and, with the shown differences, non-Newtonian effects need to be integrated into these systems,” said Taghizadeh. “Identifying areas that are prone to plaque formation around the carotid bifurcation can help in early diagnosis of disease.”

Source: “A comparison of Newtonian and non-Newtonian pulsatile blood rheology in carotid bifurcation through fluid solid interaction hemodynamic assessment based on experimental data,” by Milad Samaee, Ahmad Nooraeen, Mohammad Tafazzoli-Shadpour, and Hadi Taghizadeh, Physics of Fluids (2022). The article can be accessed at http://doi.org/10.1063/5.0094656 .