Low Density Lipoprotein and Non-Newtonian Oscillating Flow Biomechanical Parameters for Normal Human Aorta

Area of Science:

• Cardiovascular Biomechanics
• Fluid Dynamics
• Biomedical Engineering

Background:

• Hemodynamic parameters during cardiac pulse waves are key atherogenic factors.
• Non-Newtonian blood viscosity simulation is essential for accurate hemodynamic analysis.
• Understanding low-density lipoprotein (LDL) distribution aids in identifying atherosclerosis-prone aorta regions.

Purpose of the Study:

• To analyze biomechanical parameters and LDL distribution in the aorta under oscillating flow.
• To compare Newtonian and non-Newtonian blood viscosity models for hemodynamic analysis.
• To identify aorta regions susceptible to atherosclerosis based on flow parameters.

Main Methods:

• Computational fluid dynamics (CFD) was used to analyze the human aorta under oscillating flow.
• Averaged wall shear stress (AWSS), oscillatory shear index (OSI), and relative residence time (RRT) were calculated.
• Four non-Newtonian models and one Newtonian model were tested for blood viscosity.

Main Results:

• Consistent aorta patterns were observed across tested blood flow models.
• Concave aorta regions, particularly near the left subclavian artery and ascending aorta, showed high OSI, low AWSS, and high RRT.
• These concave regions exhibited significantly elevated LDL concentrations (up to 35% higher than entrance values), correlating with high RRT.

Conclusions:

• The non-Newtonian power law model effectively approximates viscosity, WSS, OSI, RRT, and LDL distribution.
• Concave aorta regions are identified as highly susceptible to atherosclerosis.
• Relative residence time (RRT) is a valuable indicator for predicting atheromatic plaque localization in the aorta.