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Effects of Heart Dynamic Motion on Blood Hemodynamics and LDL Accumulation in Coronary Bifurcation

Olyaei, Mostafa | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53613 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar
  7. Abstract:
  8. In this thesis, the effect of heart dynamic motion and pulsatile inflow on blood hemodynamics and LDL permeation into the arterial wall in a 3-D coronary artery bifurcation was investigated. To determine the effect of each factor alone and simultaneous effect of both factors i.e. heart dynamic motion and pulsatile inflow, flow simulations were performed in four cases i.e. steady-static, steady-dynamic, pulsatile-static, and pulsatile-dynamic. The results of flow simulations showed that dynamic geometry and pulsatile inflow have considerable impact on temporal variations of wall shear stress (WSS), even though the effect of pulsatile inflow on WSS variation dominates over the effect of dynamic geometry in the pulsatile-dynamic case. After simulating the blood flow in the lumen, the results of the pulsatile-dynamic case were used to simulate the shear dependent LDL permeation into the arterial wall. First, the transport properties of the endothelium were calculated as a function of the local shear stress index (SSI). In one case, shear stress index (SSI) was equal to time-averaged wall shear stress (TAWSS), and in another case a new shear stress index (SSI) was defined by combining time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI). Then, in each case, the shear dependent LDL and plasma fluxes were calculated and employed as boundary conditions for the wall domain as a single-layer porous media. The results showed that defining the new shear stress index (SSI) changed the LDL flux up to 45 percent which made the relative importance of myocardial wall of LAD and outer wall of LCX as athero-prone regions somewhat equal. Moreover, maximum LDL concentrations were observed in the myocardial wall of LAD and outer wall of LCX. Thus, these two regions were identified as being prone to the formation of primary plaques which is also in agreement with clinical research
  9. Keywords:
  10. Coronary Bifurcation ; Computational Fluid Dynamics (CFD) ; Shear Stress ; Low Density Lipoprotein (LDL) ; Wall Shear Stress (WSS) ; Time-Averaged Wall Shear Stress (TAWSS)

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