Investigating the Effects of Stent-Graft Structural Features Using Computational Fluid Dynamics

The objective of this study was to assess the effects structural features of endovascular stent-grafts used to repair abdominal aortic aneurysms (AAA) have on the flow mechanics and near-wall hemodynamics using Computational Fluid Dynamics (CFD) simulations. This research compared two test case model representations: 1) a stent graft that included the wire struts in the graft walls, and 2) a stent graft that excluded the struts in the computational mesh. The two computer-aided design models were created to represent a bifurcated stent graft in the abdominal aorta, with the stent beginning in the thoracic region of the aorta and branching into the common iliac arteries. The geometries were imported as surface meshes into a commercially available CFD solver. Both models account for viscous pulsatile blood flow of the cardiac cycle using blood properties gathered from previous research. Results of the two simulations were compared by using established metrics, including oscillating shear index (OSI), time average wall shear stress (TAWSS), and relative residence time (RRT), all of which are used to predict the likelihood of clot formation, endothelial damage, and device failure. Scalar and vector scenes allow for visualization, and data was exported for quantifying threshold results of the parameters. Due to the expense of stent grafts and the risks involved with clinical trial, CFD modeling is becoming more prominent in endovascular repair of aneurysms. The overarching goal of this study is to enhance current models of stent grafts, which can potentially be used to complement clinical trial for stent graft development.