Simulation of the Influence of Hypertension on Low Density Lipoprotein (Ldl) Permeation into Multilayer Coronary Bifurcation

Moniri Piri, Mohammad | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53555 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar
  7. Abstract:
  8. Atherosclerosis, due to the penetration of low-density lipoprotein particles (LDL) into the arterial wall, is one of the most common and death-leading diseases in today's world. Due to its importance, extensive research has been conducted on the factors that affect this disease. In this thesis, a numerical study of the effects of Wall Shear Stress (WSS), non-Newtonian behavior of blood, different hematocrit values, and blood pressure on LDL permeation through the artery wall layers are investigated in a 4-layer wall model of a coronary bifurcation. To obtain the velocity and concentration fields in the domain, momentum, Brinkman, and mass transport equations are solved in the lumen and wall layers using Ansys/Fluent software. The results show that considering the WSS's effects on endothelium layer properties in bifurcations is crucial and will lead to concentration profiles completely different from a constant properties model. Our computations show that a giant accumulation of LDL particles in intima layer of the outer wall of LAD branch, especially in low WSS regions, may lead to atherosclerosis. Also, considering the non-Newtonian behavior of blood in bifurcations is essential due to its direct effect on WSS. A pressure-induced increase in half-width of leaky junctions may be responsible for the higher risk of atherosclerosis in hypertension. Also, it is shown that the dominant mechanism in LDL permeation through the wall is convection, and also, hypertension increases the effect of mass transfer by convection mechanism more than that of the diffusion mechanism. The results of this study are consistent with different clinical studies
  9. Keywords:
  10. Atherosclerosis ; Low Density Lipoprotein (LDL) ; Wall Shear Stress (WSS) ; Blood Pressure ; Coronary Arteries Disease (CAD) ; Coronary Bifurcation ; Hematocrit

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