Low-Density Lipoprotein concentration in the normal Left Coronary Artery tree

Area of Science:

• Cardiovascular Science
• Biomedical Engineering
• Computational Fluid Dynamics

Background:

• Atherosclerosis genesis and progression are significantly influenced by blood flow and molecular transport within the cardiovascular system.
• Understanding Low Density Lipoprotein (LDL) concentration is critical for studying atherosclerosis.
• This study computationally investigates LDL site concentration in a normal human Left Coronary Artery (LCA) tree.

Purpose of the Study:

• To elucidate the distribution and concentration of LDL within the entire 3D normal human LCA tree.
• To identify key factors influencing LDL accumulation in the LCA, a region prone to atherosclerosis.

Main Methods:

• Construction of a 3D geometry model of the normal human LCA tree using end-diastolic angiographic data.
• Numerical simulation coupling flow and transport equations with realistic wall boundary conditions.
• Analysis of LDL concentration variations based on water infiltration velocities and molecular diffusivities.

Main Results:

• High LDL concentrations were observed at bifurcations opposite flow dividers in proximal LCA regions.
• Area-averaged normalized luminal surface LDL concentrations increased with higher water infiltration velocities.
• Peak normalized LDL concentrations at the Left Main Coronary Artery (LMCA) bifurcation varied with molecular diffusivity.

Conclusions:

• LDL concentration is elevated where Wall Shear Stress (WSS) is low and on concave arterial walls.
• Decreased molecular diffusivity and increased water infiltration velocity significantly increase LDL concentration.
• Water infiltration velocity at the vessel wall is a primary factor affecting elevated LDL concentration, potentially linked to endothelial proximity velocity paths.