Impact of alterations in target vessel curvature on branch durability after endovascular repair of thoracoabdominal aortic aneurysms.

Objective: The aim of this study was to evaluate curvature and its effect on the durability of visceral and renal branches in patients undergoing endovascular repair of thoracoabdominal aortic aneurysms (TAAAs) with fenestrated/branched endovascular aneurysm repair (F/B-EVAR).
Methods: Quantitative branch vessel curvature assessment on branches arising from reinforced fenestrations was performed for 168 patients undergoing F/B-EVAR for type II and type III TAAAs. Preoperative and postoperative centerline coordinates were obtained using iNtuition (TeraRecon, Foster City, Calif) and exported into MATLAB (The MathWorks, Inc, Natick, Mass) based on thin-slice computed tomography imaging. Spline interpolation was applied to the centerline coordinates and resampled at 100 equally spaced points, and curvature calculations (κ, mm(-1)) were applied. Global and maximal curvatures for each of the target vessels were measured and categorized by severity. Categories for curvature were 0 to 0.05 mm(-1) (low), 0.05 to 0.1 mm(-1) (medium), 0.1 to 0.15 mm(-1) (high), and >0.15 mm(-1) (extreme) for global curvature and 0 to 0.2 mm(-1), 0.2 to 0.4 mm(-1), 0.4 to 0.6 mm(-1), and >0.6 mm(-1), respectively, for maximum curvature. Curvature variances were assessed for an association with vessel patency and need for reintervention.
Results: There were 558 vessels that underwent analysis based on repairs involving 650 vessels, whereby 92 vessels were excluded as they were treated with an external helical branch (58 celiac arteries and 34 superior mesenteric arteries). There was a significant difference found before and after F/B-EVAR for the global celiac artery curvature (median difference, -0.01; P < .001), global left renal artery curvature (median, -0.01; P = .014), maximum left renal artery curvature (median, 0.05; P < .001), and maximum right renal artery curvature (median, 0.03; P = .009). Maximum artery curvature was found to have shifted distally in all vessels postoperatively; 37 adverse events (AEs) were observed in 30 patients (6 branched occlusions and 31 reinterventions [24 type III endoleaks, 5 vessel stenoses, and 2 vessel occlusions]). The majority of AEs (>70%) occurred within the range of low to medium curvature. Univariate analysis found gender to be a dependent variable associated with high (maximum) preoperative curvature (odds ratio, 0.395; P = .02). The use of self-expanding stents (vs balloon-expandable stents alone) in vessels with high preoperative curvature (>0.6 mm(-1)) was significant in the right renal artery (P = .044).
Conclusions: This study did not show a significant relationship between the severity of artery curvature or changes in curvature and AEs found for visceral or renal branches after F/B-EVAR for extensive TAAA. Surprisingly, the majority of AEs occurred in low- and medium-curved vessels. This study is limited in that it does not take into account other factors that may affect AEs, like motion, which would be valuable in future studies.
(Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)