Effect of the Terminal Aortic Diameter on the Patency Rate of Iliac Limbs after Endovascular Aortic Repair

Objective: Endograft limb occlusion (ELO) is a complication of endovascular aneurysm repair (EVAR). In this study, we investigated the mechanism and anatomical features of ELO. Materials and Methods: We retrospectively reviewed 227 consecutive patients with abdominal aortic aneurysm who underwent EVAR between 2007 and 2017. We then analyzed the preoperative risk factors and anatomical features of patients with ELO. Results: A total of nine patients had ELO (4.0%). The diameter of the terminal aorta was significantly smaller in patients with ELO than in patients without ELO (18.0 mm vs. 22.3 mm, p=0.039). We measured the diameter of each limb near the terminal aorta. The smaller limb (SL) was occluded in all patients with occlusion. The difference between the larger limb (LL) and the SL (LL-SL) was significantly larger in patients with ELO than in patients without ELO (4.0 mm vs. 1.7 mm, p<0.001). The following were considered risk factors for ELO: younger age, narrow terminal aorta, severe calcification at the terminal aorta, and use of an Endurant device. Conclusion: ELO occurs when the diameter of one side of the stent graft limb is small compared with the diameter of the other side owing to the narrow terminal aorta and calcification.