Blood Flow in an Abdominal Aorta Aneurysm Post Endovascular Repair

Background: Abdominal aortic aneurysm (AAA) is a localized enlargement of the abdominal aorta, when about 85% of the AAA, occur below the kidneys with the rest either at the level of or above the kidneys. Rupture of the aneurysm usually leads to death. Endovascular aneurysm repair (EVAR) stent grafts (SGs) offer an alternative treatment for conventional open vascular surgery. In cases of other aortic aneurysm which are either at the level of or above the kidneys, the surgeon must enable blood flow to the visceral arteries or kidneys and gut arteries. In one of the solutions for this cases, two ‘chimney’ stents are inserted into the renal arteries, parallel to the main aortic SG.

Methods: A healthy abdominal aorta was evaluated in comparison with several configurations of an aorta post chimney endovascular aneurysm repair (ChEVAR). Computational fluid dynamics (CFD) simulations of pulsatile blood flow during the cardiac cycle, were employed, and the effect of these SGs on the abdominal aortic blood flow and the wall shear stresses (WSSs), were analyzed.

Results: The results show that EVAR procedures, improves the flow in the aortic and the renal arteries. In cases of ChEVAR, the CSGs introduces variations in blood flow patterns and formation of stagnant regions downstream from the CSGs throughout the cardiac cycle, which can contribute to thrombosis.

Conclusion: These procedures are a convenient solution for the physician and the patient, but we still need to improve and adapt them for each patient.