Wall shear stress on LDL accumulation in human RCAs

Area of Science:

• Cardiovascular Science
• Biomedical Engineering
• Computational Fluid Dynamics

Background:

• Atherosclerosis development is linked to blood flow patterns and molecule transport in the cardiovascular system.
• Specific arterial regions with altered hemodynamics and high lipoprotein concentrations are prone to atherosclerosis.
• The arterial wall's semi-permeable nature and its dependence on wall shear stress are critical factors.

Purpose of the Study:

• To computationally model low-density lipoprotein (LDL) transport in diseased human coronary arteries.
• To investigate the relationship between wall shear stress (WSS) and LDL concentration at the arterial wall.
• To assess the impact of shear-dependent endothelial permeability on LDL transport.

Main Methods:

• Utilized image-based 3D reconstructions of six diseased human right coronary arteries (RCAs) from angiography and IVUS.
• Employed numerical simulations coupling fluid dynamics and transport equations with realistic boundary conditions.
• Incorporated the Kedem-Katchalsky equation to model endothelial water infiltration and solute dynamics.

Main Results:

• Luminal surface LDL concentration was found to be flow-dependent and varied with arterial geometry.
• A medium correlation (Pearson) was observed between low WSS and elevated LDL concentrations.
• Shear-dependent water infiltration significantly impacted LDL elevation, with area-averaged normalized LDL concentration increasing by 9.6% compared to constant infiltration.

Conclusions:

• Low WSS is a significant factor in elevated LDL concentrations at the arterial wall, contributing to atherosclerosis.
• Computational fluid dynamics models incorporating LDL transport must consider shear-dependent endothelial permeability for accurate predictions.
• The water infiltration velocity at the vessel wall is a primary driver of LDL concentration elevation.