Influence of Anatomic Angulations in Chimney and Fenestrated Endovascular Aneurysm Repair

Abstract

The lack of widespread availability of Fenestrated endovascular aneurysm repair (F-EVAR) encouraged alternative strategies. Hence, Chimney graft (CG)-EVAR spread when costs, manufacturing delays, or anatomy preclude F-EVAR. Our objective is to evaluate CG- and F-EVAR outcomes depending on the angulation of target renal arteries and hostility of iliac accesses in order to determine the potential impact of a choice made between both techniques on the basis of preoperative anatomic criteria. Consecutive patients treated by CG-EVAR or F-EVAR, from January 2010 to January 2015, were considered for inclusion. Anatomic parameters were defined by preoperative computed tomography angiography. A subgroup analysis was performed depending on renal arteries' angulation (cut-off: -30°) and iliac arteries' hostility (cut-off: diameter<6mm, tortuosityindex=3). Twenty-six patients were included the CG group (mean age 74.7±6.9years, 30 target vessels) and 66 in the F-EVAR group (71.7±7.9years, 133 target vessels). Infrarenal aortic neck length was significantly longer for CG-EVAR (3.3±3.7 vs. 1.8±3.2mm, P=0.04), while the distance between the superior mesenteric artery and highest renal artery was shorter in the CG group (11.7±6.2mm vs. 14.1±5.9mm, P=0.06). Longitudinal angulation of the right renal artery was not statistically different between both groups, while the left renal artery presented with a significantly more downward angulation in the CG group (-32.0±15.3 vs. -19.0±19.6, P=0.003). There were significantly more grade 3 iliac tortuosity indexes for CG-EVAR (P=0.03) with significantly smaller external iliac diameters (7.8±1.7 vs. 8.8±1.6mm, P=0.0009). There was 1 renal artery early occlusion in the <-30° CG subgroup and 2 in the <-30° F-EVAR subgroup where severe downward angulation crushed the stents, with a tendency toward higher early occlusions compared with the ≥-30° F-EVAR subgroup (P=0.054). Mean follow-up duration was 20months in the CG group and 14 in the F-EVAR group. Kaplan-Meier estimates showed no significant difference in terms of overall survival, freedom from reintervention, freedom from type I or III endoleak, or patency. In the CG group, 14 patients (53.8%) presented with hostile iliac accesses without any significant difference in terms of limb events. CG-EVAR is a complementary strategy to F-EVAR, and understanding which technique is applicable to which patient is important to improve outcomes. Our results suggest that considering renal artery angulation and diameter, iliac artery hostility, and aortic neck length among other parameters may help the surgeon make a decision toward the endovascular strategy that seems best suited for each specific patient.