Stability of Coronary Arteries Arteriosclerosis Using Fluid-Structure Interaction

Ebrahimi Hasratanloo, Sina | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52946 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Fallah Ragabzadeh, Famida
  7. Abstract:
  8. Coronary arteries often experience tortuosity under internal blood pressure and longitude axial twisting. Arterial tortuosity can enhance the stress concentration on the artery walls. Now if the coronary arteries suffer from atherosclerosis (a common disease among adults) the stress concentration on the tortuous artery plaque will be enhanced as well. Increased stress on the plaque may result in plaque rupture and its consequent damages. This study aims to investigate the stress concentration on the plaques and blood flow patterns within the coronary arteries with plaque. Moreover, the plaque growth was predicted taking into account various geometrical parameters including fibrous cap thickness, lipid core percentage, lipid coverage angle, plaque length, and stenosis percentage under three buckling states (axial, twisting, and helical) using finite element analysis and considering solid-fluid interactions.The results showed that in the case of bending buckling, the maximum deformation of the artery depended on all the geometrical parameters except the lipid core percentage. Furthermore, with an increase in the transverse deformation of the artery, the stress concentration on the plaque will be also enhanced. The magnitude of the vortex formed at maximum arterial displacement was lower compared to the case with the lowest displacement. Therefore, it can be said that the arterial tortuosity will decline the plaque sedimentation. According to simulation results, by increasing the plaque percentage, its length and fibrous cap thickness, the vortex formed upon bending buckling will be incremented as well.One-way twisting of the artery at low lumen pressures resulted in the linear increment of the torque by the twisting angle until the time of buckling. Also, the stress concentration of the plaque exhibited an increase which can facilitate the plaque rupture. The shear stress of the wall, however, declined by raising the twisting angle. Under high lumen pressure, the one-way twisting of the artery will make it behave in a helical-like manner under which the increase in the twisting angle will elevate the shear stress of the walls.The results regarding the effects of the blood mechanical properties on the vortex magnitude under bending buckling suggest that the vortex formed in the diabetic patients with high hematocrit percentage is 14% lower than the normal people implying that the plaque formation and growth is less likely in the diabetic patients with high hematocrit percentage as compared with normal subjects
  9. Keywords:
  10. Artery Buckling ; Atherosclerosis ; Fluid-Structure Interaction ; Critical Buckling Pressure ; Plaque Rupture ; Coronary Arteries

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