Sealing Zone Failure Decreases the Long Term Durability of Endovascular Aneurysm Repair

Abstract

Objective: Endovascular aneurysm repair (EVAR) has a higher long term aneurysm related mortality rate compared with open surgery, mainly due to aneurysm rupture. Loss of stent graft to vessel apposition at the EVAR sealing zones is a potential cause of post-EVAR rupture. This study aimed to investigate sealing zone failure and its relationship with post-EVAR rupture.

Methods: This was a retrospective structured review of pre- and post-operative computed tomography (CT) scans of 399 consecutive patients treated with standard bifurcated EVAR. The primary outcome was total loss of seal at last post-operative CT. Secondary outcomes were partial loss of seal, standard follow up detection, post-EVAR rupture, aneurysm sac development, and endoleaks.

Results: During a median follow up of 5.3 years, total and partial loss of seal occurred in 85 (21.3%) and 78 (19.5%) patients, respectively. Initial mean sealing zone lengths were within current recommendations but decreased over time, mainly due to vessel dilatation. Mean proximal sealing length at the one month CT was 15.5 ± 10.5 mm (95% confidence interval [CI] 12.6 - 18.5 mm) in the group with total loss of seal, 14.3 ± 6.9 mm (95% CI 12.2 - 16.4 mm) with partial loss of seal, and 23.2 ± 7.4 mm (95% CI 22.3 - 24.0 mm) with preserved seal through follow up (p < .001). Mean iliac sealing lengths were 22.4 ± 12.1 mm (95% CI 18.9 - 25.8 mm) if total loss and 21.8 ± 10.0 mm (95% CI 19.6 - 24.0 mm) if partial loss of seal vs. 34.7 ± 12.4 mm (95% CI 33.8 - 35.7 mm) if preserved seal. Larger vessel diameters were associated with loss of seal in both the proximal and distal sealing zones. During the study period, 13 post-EVAR ruptures occurred, all preceded by CT findings of total (n = 7) or partial (n = 6) loss of seal. Aneurysm sac expansion was seen in 40% of patients with total loss of seal, 18% with partial loss of seal, and 6.6% with preserved seal.

Conclusion: Loss of seal after EVAR is frequent and associated with post-EVAR rupture. Increased recommended sealing zones lengths and focus on sealing zones in surveillance may reduce post-EVAR ruptures and aneurysm related death.

Keywords: Aortic aneurysm; CT; EVAR; Long term; Rupture; Surveillance.