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Numerical Study on the Effect of High-Density Lipoprotein (HDL)on early atherosclerotic plaque formation in Coronary Arteries

Roostaie, Saeed | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57919 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar
  7. Abstract:
  8. Coronary artery disease (CAD) is characterized by the accumulation of fats, cholesterol, and other substances in the artery walls, leading to thickening and narrowing, commonly referred to as plaque formation. Clinical studies have shown that this process primarily occurs in regions of low wall shear stress. This study numerically investigates the influence of factors such as low-density lipoprotein (LDL) concentration, the role of antioxidants, and specifically the antioxidant effect of high-density lipoprotein (HDL) and the reverse cholesterol transport (RCT) process on plaque formation in a three-dimensional bifurcation geometry of the left main coronary artery (LMCA) using Fluent software. The blood flow is simulated as unsteady, employing boundary conditions derived from experimental studies, with the Navier-Stokes and continuity equations solved within the lumen. Using the extended Kedem-Katchalsky equations and a three-pore model for the endothelial cells layer, the plasma filtration velocity and the flux of LDL, HDL, and monocytes into the wall are calculated based on hemodynamic parameters (time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI)) and particle size. The concentration of different species in the wall is modeled by solving the Darcy equation and the advection-diffusion-reaction equations. The wall thickness growth after 15 and 30 years for different cases is then calculated and compared based on the species concentrations. The present modeling results show that reducing LDL concentration, as the most influential species in plaque formation, from high levels to moderate and safe levels can significantly reduce plaque formation (up to 82% after 15 years). Furthermore, antioxidants, particularly HDL, which has a similar role, are more effective in mitigating the disease beyond their ability to reduce LDL oxidation. The reverse cholesterol transport role of HDL can, with varying efficacy based on conditions, reduce plaque formation and smooth plaque thickness growth, showing significant effects in advanced stages of the disease. These effects make HDL, after LDL, one of the most influential species in the disease, suggesting its therapeutic use or drugs that increase its RCT levels for plaque reduction. This simulation shows a 57% reduction in plaque thickness growth after 15 years of therapeutic use of HDL
  9. Keywords:
  10. Coronary Arteries Disease (CAD) ; Coronary Bifurcation ; Low Density Lipoprotein (LDL) ; High Density Lipoprotein (HDL) ; Antioxidant ; Reverse Cholesterol Transport (RCT) ; Artery Stenosis

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