Geometric Analysis of Fenestrated and Multibranched Aortic Endografts – Relevance of Branches’ Angulation for Type III Endoleaks and Branch Thrombosis

Abstract

Introduction: Endovascular treatment of thoracoabdominal aortic aneurysms (TAAA) is the gold standard procedure in most vascular centers. The goal of this study is to determine geometric risk factors for the development of type III endoleaks and branch thrombosis in patients treated with fenestrated (F-) or multibranched (B-) endovascular aneurysm repair (EVAR). The primary endpoint was the post-operative end-stent angulation for both FEVAR and BEVAR and its relevance in type III endoleak and branch thrombosis. Methods: From November 2013 to March 2018, consecutive patients with TAAA treated with a FEVAR of BEVAR were selected. Demographic variables, aneurysm anatomy and endografts’ conformation were analyzed retrospectively. Results: 24 patients underwent CTA before and after FEVAR (n=8) and BEVAR (n=16), and 86 vessels were successfully catheterized (celiac artery n=14, superior mesenteric artery n=24, right renal artery n=24, left renal artery n=22, polar renal artery n=2). All patients were considered ASA III and the median age was 72 years (49-81). The mean aneurysm diameter was 67.4mm (54.4-92.7). The mean follow-up period was 22.7 months and the rate free of type III endoleak and thrombosis at 24 months were 89% and 88%, respectively. All the FEVAR vessels (n=26) were catheterized using 1 stent, while 16.7% (n=10) of the BEVAR vessels (n=60) required 2 stents. The total stent longitude in FEVAR was significantly shorter than in BEVAR (26.67±4.4mm vs 6.50.63±8.51mm, p=0.000), as was the radius of curvature (FEVAR 34.75±18.7º; BEVAR 64.92±18.2º, p=0.000). There were no significant differences between FEVAR and BEVAR in terms of rate of type III endoleak (p=0.240) or branch thrombosis (p=0.544). The overall rate of branch thrombosis was 9.3% (n=8) and was more frequent in smaller vessels (5.00±1.25mm vs 7.30±1.8mm, p=0.001) and in vessels with higher stent oversizing (36.87±23.6% vs 3.57±13.8%, p=0.000). The overall rate of type III endoleaks was 11.6% (n=10), and all cases were associated with 4-branch endografts (p=0.030). 60% of the vessels that required 2 stents showed a type III endoleak, which was significantly higher than the vessels treated with 1 stent (5.3%) (p=0.000). A higher rate of type III endoleak was observed in greater vessels (7.63±0.59mm vs 7.04±2.0mm, p=0.029) and with wider stents (8.40±1.1mm vs 7.18±1.2mm, p=0.002). A positive correlation was found between the presence of endoleak and the need for 2 stents per vessel (p=0.000) but not with the total longitude of the stent (p=0.103). The end-stent angulation, the radius of curvature and the total stent longitude did not entail a higher rate of endoleak (p=0.719; p=0.634; p=0.314 respectively) or thrombosis (p=0.424; p=0.102; p=0.205 respectively). Conclusion: In our series, the end-stent angle does not relate with a higher risk of type III endoleak nor with branch thrombosis, neither does the radius of curvature or the total stent longitude. Care must be taken when measuring the vessel’s diameter, in order to choose the adequate stent size, as small vessels and excessive stent oversizing entail a higher risk of branch thrombosis. Longer stents should be considered rather than using more than one, since a higher number of stents per vessel associates a higher risk of endoleak.