Aortic Anatomy and Complications of the Proximal Sealing Zone after Endovascular Treatment of the Thoracic Aorta

Abstract

Technical and clinical success of thoracic aortic endovascular procedures relies mainly on the choice of the proximal sealing zone (PSZ). The latter can be affected by multiple complications, all of them having a potential gravity and a direct link with the quality of the PSZ. The objective of this study was to analyze the risk factors of PSZ complications occurrence. Between 2007 and 2015, all the patients treated by a thoracic stent graft in zones 2, 3, or 4 were retrospectively reviewed, with analysis of the preoperative and postoperative angio-computed tomography. Proximal sealing zone complications are type Ia endoleaks, bird beak ≥20mm, malposition ≥11mm, migration ≥10mm, and retrograde dissection. Three types of potential risk factors were analyzed: (1) related to the patients (age, gender, pathology, urgency, hybrid surgery); (2) related to the stent graft (bare or covered proximal stent, degree of oversizing, number of stents, generation); (3) related to the morphology (radius of curvature, diameter, degree of conicity, calcifications and thrombus of the neck, depth of the arch, angulation of the proximal sealing zone, and tortuosity index of the arch and the thoracic aorta. Seventy-six patients (mean age: 54years, 17-93years) were treated for traumatic aortic rupture (n=27, 35.5%), aortic dissection (n=26, 34%), aneurysm (n=15, 20%), and other diseases (floating thrombus, aortoesophageal fistula) (n=8, 10.5%). A hybrid surgery was carried out in 18 patients (24%). Primary technical success was 93.5% (n=71). With a mean follow-up of 29months, 30 PSZ complications were observed in 21 patients (28%): type Ia endoleaks (n=3, 4%), bird beak (n=7, 9%), malposition (n=3, 4%), migration (n=1, 1.5%), retrograde dissection (n=1, 1.5%), or several complications (n = 6, 7.8%). Among the morphological factors, 2 parameters were significantly associated with the occurrence of complications: tortuosity index (group without PSZ complications 1.62±0.2 vs. group with PSZ complications 1.72±0.2, P=0.042), and the diameter of the proximal neck (group without PSZ complications 25.7±5 vs. group with PSZ complications 31±6.0, P=0.001). Neither the demographic factors nor those related to the stent graft presented a statistically significant relation with the occurrence of complications. This work clearly highlights the relation between PSZ complications, independently of their type, and the local and global aortic morphology. A wide proximal neck,>34mm, and an important aortic tortuosity, > 1.8, are situations at risk.