Examination of near-wall hemodynamic parameters in the renal bridging stent of various stent graft configurations for repairing visceral branched aortic aneurysms

ObjectiveThis study examined the flow behavior of four stent graft configurations for endovascular repair of complex aneurysms of the descending aorta.MethodsComputational fluid dynamics models with transient boundary conditions and rigid wall simplifying assumptions were developed and used with four distinct geometries to compare various near-wall hemodynamic parameters.ResultsGraphic plots for time-averaged wall shear stress, oscillating shear index, and relative residence time were presented and compared among the four stent graft configurations of interest.ConclusionsAbrupt 90° and 180° changes in stent geometry (particularly in the side branches) cause a high momentum change and thus increased flow separation and mixing, which has significant implications in blood flow characteristics near the wall. By comparison, longer bridging stents provide more gradual changes in momentum, thus allowing blood flow to develop before reaching the target vessel.Clinical RelevanceRenal vessel patency is a well-known but rarely talked about challenge with complex aneurysm repair. Many factors need to be optimized to ensure branch vessel patency in aneurysms of the visceral segment, including bridging stent compliance transition, bridging stent material selection and design, and main body graft alignment. One topic that has not been discussed much is the flow characteristics entering the branch. Here we propose a technique to evaluate device configurations and their associated flows for their ability to maintain branch vessel patency