Effects of Iliac Tortuosity Index on Fenestrated Endovascular Aortic Aneurysm Repair for Pararenal and Thoracoabdominal Aortic Aneurysms

Purpose: To evaluate the effect of iliac tortuosity on procedural metrics and outcomes of patients with complex aortic aneurysms (cAAs) undergoing repair with fenestrated/branched endografts (f/b-EVAR [endovascular aortic aneurysm repair]). Material and Methods: The study is a single-center, retrospective review of a prospectively maintained database of patients undergoing aneurysm repair using f/b-EVAR between the years 2013 and 2020 at our institution. Included patients had at least 1 preoperative computed tomography angiography (CTA) available for analysis. Iliac artery tortuosity index (TI) was calculated using centerline of flow imaging from a 3-dimensional work station based on the formula: (centerline iliac artery length / straight-line iliac artery length). The associations between iliac artery tortuosity and procedural metrics, including total operative time, fluoroscopy time, radiation dose, contrast volume, and estimated blood loss (EBL), were evaluated. Results: During this period, 219 patients with cAAs underwent f/b-EVAR at our institution. Ninety-one patients (74% men; mean age = 75.2 +/- 7.7 years) met criteria for inclusion into the study. In this group, there were 72 (79%) juxtarenal or paravisceral aneurysms and 18 (20%) thoracoabdominal aortic aneurysms and 5 patients (5.4%) with failed previous EVAR. The average aneurysm diameter was 60.1 +/- 0.74 mm. Overall, 270 vessels were targeted, and 267 (99%) were successfully incorporated, including 25 celiac arteries, 67 superior mesenteric arteries, and 175 renal arteries. The mean total operative time was 236 +/- 83 minutes, fluoroscopy time was 87 +/- 39 minutes, contrast volume was 81 +/- 47 mL, radiation dose 3246 +/- 2207 mGy, and EBL was 290 +/- 409 mL. The average left and right TIs for all patients were 1.5 +/- 0.3 and 1.4 +/- 0.3, respectively. On multivariable analysis, the interval estimates suggest positive association between TI and procedural metrics to a certain degree. Conclusions: In the current series, we found no definitive association between iliac artery TI and procedural metrics, including operative time, contrast used, EBL, fluoroscopy time, and dose in patients undergoing cAA repair using f/b-EVAR. However, there was a trend toward association between TI and all these metrics on multivariable analysis. This potential association needs to be evaluated in a larger series. Clinical Impact Iliac artery tortuosity should not exclude patients with complex aortic aneurysms from being offered fenestrated or branched stent graft repair. However, special considerations should be taken to mitigate the impact of access tortuosity on alignment of fenestrations with target vessels, including use of extra stiff wires, through and through access and delivering the fenestrated/branched device into another (larger) sheath such as a Gore DrySeal in patients with arteries large enough to accommodate such sheaths.