Tortuosity is the Significant Predictive Factor for Renal Branch Occlusion after Branched Endovascular Aortic Aneurysm Repair

Abstract

Objective: After multi-branched endovascular aneurysm repair (mbEVAR), renal branch occlusion is the most frequent form of branch failure. Pre-operative renal angulation and post-operative morphology of the renal branch were quantified and their impact on occlusion was analyzed.

Methods: Patients who underwent mbEVAR between January 2010 and December 2013 were reviewed retrospectively. Only renal branches constructed with caudally directed cuffs were included. Patients without post-operative computed (CT) angiography were excluded. The main outcome was the primary patency of the renal branches. The renal angulation and the morphology of renal branch (bridging length, renal coverage length, tortuosity index, and angulation of distal renal artery) were quantified using CT. The impacts of morphology, implanted stents, and patient characteristics were investigated by time to event analyses.

Results: Ninety renal arteries in 49 patients were enrolled. Median follow up was 12 months (IQR 6-20 months). Balloon expandable stent grafts were used in 93% (84/90) of renal branches. Self expandable stent grafts were used in 12. Ninety-one percent (82/90) were lined with self expandable bare stents. Ten branches occluded after 8 months (median; IQR 1-14 months). Four of them underwent re-interventions, achieving secondary patency. The median renal angulation was -10° (IQR -40 to 0). The median bridging length was 42 mm (IQR 39-46 mm) and renal coverage 17 mm (IQR 12-22 mm). Median tortuosity index was 1.11 (IQR 1.04-1.19). The angulation of the distal renal artery was 140.7 ± 20.5°. In multivariate analysis, a tortuosity index > 1.11 was identified as the only significant predictor for occlusion (hazard ratio: 4.94; 95% CI: 1.01-24.30, p = .04).

Conclusions: High tortuosity was a significant predictor for the occlusion of renal branches, but renal angulation, bridging length, and the extent of renal coverage were not. By avoiding highly tortuous renal branch paths, good outcomes are expected even in upwardly directed renal arteries. Longer paths are acceptable.

Keywords: Multi-branched endovascular aneurysm repair; Renal branch occlusion; Thoraco-abdominal aortic aneurysm.