Three-dimensional & Hemodynamic Analysis of Fenestrated and Multibranched Aortic Endografts: Relevance of Stent Angulation for Type III Endoleak and Branch Thrombosis

Abstract

Introduction: Our previous work suggests that after complex endovascular aortic repair, with fenestrated (fEVAR) or multibranched (bEVAR) endografts, a higher stent curvature angle is associated with thrombosis. However, that study was performed with a 2D angle analysis without considering the relevance of the plane of angulation of each branch. The goal of this study was to determine the influence of three-dimensional branch and/or stent angulations for the development of type III endoleak and branch thrombosis after fEVAR or bEVAR. Methods: Prospective, non-randomized, single center study. Including all patients with TAAA treated electively, from 2013 to 2018, with fEVAR of bEVAR, with at least 1 post-operative CTA. Demographic data, aneurysm anatomy and endografts' conformation were collected. The hemodynamic blood force (HBF) was calculated using the Mass and Momentum Conservation equations. Results: All patients were ASAIII, the median age was 73 [49-81] years, and the mean follow-up period was 26.57±20.8 months. 110 abdominal vessels were successfully catheterized. The rate of type III endoleak was 14.3% (n=16). 88% (n=14) of cases were visceral arteries (Figure 1). 6 of cases were related to vessels treated with 2 stents (p=0.000), and 14 cases were vessels treated with branches (p=0.035). A higher rate of endoleak was observed in wider arteries (7.62±0.8mm Vs 6.81±1.9mm, p=0.002) but not with longer stents (p=0.972) or higher stent oversize (p=0.561). Higher entry (50.51±22.7º Vs 21.71±30.6º, p=0.001) and exit (45.26±27.8º Vs 16.92±23.5º, p=0.000) angulations of the stent in the sagittal plane were also associated with higher endoleak rates. Accordingly, a higher HBF in the sagittal plane (34.65x10-4±38.2x10-4N Vs 14.53x10-4±30.7x10-4N, p=0.001) was also related to endoleak. The rate of branch thrombosis was 7.1% (n=8). All cases were renal arteries (Figure 2). Neither the number of stents per branch (p=0.461) nor the type of branch (p=0.430) were associated with thrombosis. A higher rate of thrombosis was observed in smaller arteries (5.00±1.3mm Vs 7.07±1.8mm, p=0.001) and with higher stent oversize (36.9±26.6% Vs 5.63±15.6%, p=0.001) but not with the stents length (p=0.647). Further, an oversize inferior to 15% has a negative predictive value (NPV) of 100% (p=0.001). Higher entry (68.63±6.2º Vs 30.07±33.6º, p=0.012) and exit (70.86±60.7º Vs 16.18±22.3º, p=0.005) angulations of the stent in the coronal plane were also associated with higher rates of thrombosis. Accordingly, a higher HBF in the coronal plane (39.72x10-4±42.6x10-4N Vs 16.71x10-4±23.2x10-4N, p=0.013) was also related to thrombosis. When analyzing exclusively the renal arteries a higher exit angle of the stent in the transversal plane (91.87±24.6º Vs 62.13±52.1º, p=0.041) was related with thrombosis. Moreover, an exit angle of the stent in the coronal plane under 61º has a NPV of 100% (p=0.001). The rate free from type III endoleak and thrombosis at 24 months were 87% and 91%, respectively. Conclusion: Type III endoleak is mostly associated with visceral arteries, while branch thrombosis is related to renal arteries. To avoid thrombosis, the stent oversize should fall behind 15% and the transversal exit angle of the stent should not exceed 61º. Longer stents should be considered rather than using more than one, to avoid endoleak.Figure 2Kaplan-Meier curve comparing time free from thrombosis between visceral & renal arteries.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Disclosure: Nothing to disclose