Fluid–Structure Interaction in Healthy, Diseased and Endovascularly Treated Abdominal Aortic Aneurysms

Abdominal aortic aneurysms are irreversible dilations of the infrarenal aorta. If left untreated the aneurysm may continue to grow until eventually rupturing. Endovascular aneurysm repair (EVAR) is an established method for the treatment of abdominal aortic aneurysms (AAAs). Complications arising from this treatment include endoleaks and graft migration. Computational methods such as FEA, CFD and FSI can be used to investigate both the disease manifestation and its treatment. FSI is a particularly useful tool for the investigation of EVAR as both the fluid forces acting on the graft and stresses on the aneurysm wall are of interest. This work investigates the stresses and haemodynamics in healthy, diseased and treated aneurysms through the use of FSI. Higher stresses and more disturbed haemodynamics are seen in aneurysms than in a healthy aorta. The insertion of a stent-graft significantly reduces the aneurysm wall stress and redistributes it. The stent-graft is subject to large haemodynamic forces which can cause migration of the device. These forces do not necessarily act primarily in a caudal direction, hence resulting in a non-caudal migration. The inclusion of patient-specific data such as patient-specific pressure and graft oversize was investigated. These were found to have a large effect on the accuracy of the results and in future best efforts should be made to include as much patient-specific data as possible in numerical models.