Impact of Stent-Graft Oversizing on Gutter Areas after Chimney Graft Repair for Complex Abdominal Aortic Aneurysms

Background: The aim of this retrospective study was to examine the impact of graft oversizing on gutter area and stent compression in chimney graft (CG) for complex abdominal aortic aneurysm (CAAA) repair. The influence of stent-graft oversizing on type Ia endoleaks and bridging stent occlusion rates was also examined. Methods: Preoperative and postoperative computed tomographic angiography scans of patients requiring CGs for CAAA between June 2009 and April 2013 in our institution were analyzed. Two groups were identified: proximal oversizing of the stent-graft component < 25% (group 1) and > 25% (group 2). Relative gutter areas were calculated and compared between both groups. Incidence of target vessel stent compression, target vessel occlusions, and type Ia endoleaks was also analyzed. Results: Of 39 patients treated with CG during the study period, 23 fulfilled the selection criteria for analysis. Group 1 included 10 patients and group 2 included 13 patients (mean oversizing: 18.4 +/- 4.9% and 34.5 +/- 6% respectively). Relative gutter areas were significantly higher in group 1 when compared with group 2 (6.1 +/- 2.1% vs. 4.2 +/- 3.2%, P = 0.03). No stent compression and no target vessel occlusion occurred in either groups. There was no statistical difference in type Ia endoleak in both groups (group 1 n = 0, group 2 n = 2; P = 0.48). Conclusions: In our study, a > 25% stent-graft oversizing reduced the gutter area without modifying the bridging stent patency. However, no benefit in terms of type Ia endoleak was observed.