Evaluation of Hemodynamic Properties After Chimney and Fenestrated Endovascular Aneurysm Repair.

ABSTRACT

BACKGROUND: Fenestrated (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. METHODS: Preoperative and postoperative computed tomography angiographies have been used to reconstruct patient-based models. Data of 3 patients, for each modality, were analyzed. Following geometric reconstruction, computational fluid dynamics simulations were used to extract near-wall and intravascular hemodynamic indicators, such as pressure drops, velocity, wall shear stress, time averaged wall shear stress, oscillatory shear index, relative residence time, and local normalized helicity. RESULTS: An overall improvement in hemodynamics was detected after repair, with either technique. Preoperatively, a disturbed prothrombotic wall shear stress profile was recorded in several zones of the sac. The local normalized helicity results showed a better organization of the helical structures at postoperative setting, decreasing thrombus formation, with both modalities. Similarly, time averaged wall shear stress increased and oscillatory shear index decreased postoperatively, signaling nondisturbed blood flow. The relative residence time 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). CONCLUSIONS: ChEVAR and FEVAR seem to improve hemodynamics toward 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.