Computational Fluid Dynamics and Wall Mechanics of Pre- and Post-Operative Abdominal Aortic Aneurysms

摘要

In the present work we numerically evaluated the biomechanical environment of pre- and post-operative aneurysms and examined the cumulative ffect of factors such as the presence of localized thrombus, non-uniform material properties, and patient-specific geometry. Flow disturbance was intensified through the pre-operative aneurysm sac with the onset of diastolic conditions and the obstruction of the localized thrombus. This led to increasedrnflow-induced forces, particularly in the normal direction to the wall. Similarly, the thrombus localized the Von Mises stress where changes in geometry and material property occur, while simultaneously shielding the AAA wall from elevated mechanical forces.rnUnder post-operative conditions, the EVG restores normal blood flow through the arterial lumen. A region of increased wall shear stress gradient exists along the posterior neck of the graft attachment site due to angula-tion of the aneurysm neck. At peak systolic pressure, the flow-induced displacement force on the graft may be sufficient to cause graft migration. The implantation of the EVG reduces the stresses exerted on the aneurysm wall, decreasing the Von Mises stress within the aneurysm by 83% in comparison with the pre-operative conditions. The maximum Von Mises stress at the post-operative aneurysm wall is 96% lower than that experienced by the en-dovascular graft. Stress remained uniformly distributed on most of the graft, but localized at the proximal attachment site due to contact forces between the graft and the arterial wall.