Evaluation of Hemodynamic Properties After Chimney and Fenestrated Endovascular Aneurysm Repair

Abstract

ObjectivesFenestrated (FEVAR) and chimney (ChEVAR) endovascular aortic repair have been applied in anatomically suitable complex aortic aneurysms. However, local hemodynamic changes may occur after repair. This study aimed to compare FEVAR’s and ChEVAR’s hemodynamic properties, focusing on visceral arteries. MethodsPre- and post-operative computed tomography angiographies (CTAs) have been used to reconstruct patient-based models. Data of three patients, for each modality, were analyzed. Following geometric reconstruction, computational fluid dynamics (CFD) simulations were used to extract near-wall and intravascular hemodynamic indicators, as pressure drops, velocity, wall shear stress (WSS), time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT) and local normalized helicity (LNH). ResultsAn overall improvement in hemodynamics was detected after repair, with either technique. Preoperatively, a disturbed pro-thrombotic WSS profile was recorded in several zones of the sac. The LNH results showed a better organization of the helical structures at post-operative setting, decreasing thrombus formation, with both modalities. Similarly, TAWSS increased and OSI decreased post-operatively, signaling non-disturbed blood flow. The RRT was locally reduced. The flow in visceral arteries tended to be more streamlined in ChEVAR, compared to evident recirculation regions at renal and superior mesenteric artery fenestrations (p=0.06). ConclusionChEVAR and FEVAR seem to improve hemodynamics towards normal values with a reduction of recirculation zones in the main graft and aortic branches. Visceral artery flow comparison revealed that ChEVAR tended to present lower recirculation regions at parallel grafts’ entries while FEVAR showed less intense flow regurgitation in visceral stents.