Is Multiple Overlapping Uncovered Stents Technique Suitable for Aortic Aneurysm Repair?

A computational fluid dynamic model to assess the impact of flow-diverter device on intra-aneurysmal flow in complex aortic aneurysm from the viewpoint of hemodynamics is presented. The aim of this study is to investigate the hemodynamic effects of an endovascular flow-diverter technique using multiple overlapping uncovered stents (MOUS) in the treatment of complex aortic aneurysm involving side branch. The placement of porous barrier such as MOUS across the aneurysm alters the blood flow pattern in the aneurysm sac. Subsequently, flow diversion effect creates a natural hemodynamic environment to promote aneurysm thrombosis, thus stabilizing the aneurysm. The study revealed that intra-aneurysmal flow was reduced and low time average wall shear stress (TAWSS), high relative residence time (RRT), and high oscillatory shear index (OSI) regions were observed in the aneurysm sac. Three to four MOUS stents produced the best hemodynamic environment for the formation of thrombus, with saccular aneurysm performing better than fusiform aneurysm from the viewpoint of hemodynamics. A result also revealed that flow in the branch vessel was not compromised suggesting the capacity of preserving patency of branch vessels while at the same time stabilizing the aneurysm. Based on the hemodynamic performance of this study coupled with existing reported clinical studies, deploying three to four MOUS stents is a feasible solution to treat aneurysm with side branch, favorably for saccular shape aneurysm.