Transarterial Embolization of Type 2 Endoleak Using Coils and N-Butyl Cyanoacrylate: The Importance of Treating the Nidus and Sac Branches

Abstract Background Transarterial embolization (TAE) of the nidus and branches prevents aneurysm sac growth due to Type 2 endoleaks (T2EL). Embolization materials include coils and liquid embolic substances such as N-butyl-2-cyanoacrylate (NBCA) glue, a type of liquid embolic glue. However, when the nidus is characterized by heterogeneous perigraft opacity on CT imaging with an ill-defined boundary within the sac, it becomes challenging to embolize the nidus directly, often resulting in the embolization of only the branches connected to it. Therefore, we aim to evaluate the efficacy of TAE for the endoleak nidus and side branches versus embolizing the side branches alone in preventing aneurysm sac enlargement after T2EL, comparing mid-term follow-up results. Materials and Methods In a single-center retrospective cohort study, we reviewed consecutive 59 patients who underwent TAE for T2EL from September 2017 to August 2022. After excluding cases with less than 6 months follow-up or without abdominal aortic aneurysm, 40 patients were included in the analysis. Initial treatment for all patients included attempts at direct embolization of the endoleak nidus and side branches using coils and NBCA glue. Even if the nidus was reached, if embolization of the nidus proved difficult, the directly connected branches were embolized instead. Data were analyzed using the Kaplan–Meier curve for estimating sac enlargement freedom, with the primary outcome being aneurysm sac diameter change post-T2EL embolization. Results No visible endoleak nidus was detected in any patient after TAE. Of all patients (n = 40), 60% (n = 24) underwent embolization via direct cannulation to the nidus. Direct TAE involving the nidus and main branches with coils, supplemented with NBCA glue, considerably hindered sac enlargement (p < 0.0001). Of 14 patients with sac enlargement, 72% (10 patients) had unsuccessful direct TAE, resulting in a significant association (p = 0.006). On the other hand, 77% (20 of 26 patients) without sac enlargement experienced successful direct TAE. Three patients displayed sac enlargement even after successful direct TAE using only NBCA glue (p = 0.04). Conclusions Direct TAE of the endoleak nidus, using coils and supplemented with NBCA glue as necessary, is effective in preventing sac enlargement after T2EL embolization.