The Relationship between Temporal Changes in Proximal Neck Angulation and Stent-Graft Migration after Endovascular Abdominal Aortic Aneurysm Repair

Abstract

In recent years, endovascular abdominal aortic aneurysm repair (EVAR) fortreating abdominal aortic aneurysms (AAA) has become quite prevalent in Japan. Thoughlittle information is available about temporal changes in proximal neck angulation due to the difficulties encountered in measuring the angle. Therefore, we examined temporalchanges in proximal neck angulation and its relationship to stent-graft migration after EVAR. Between June 2007 and March 2010, 159 patients underwent EVAR for treatment of fusiform AAAs at our hospital. This study focuses on the 80 patients among this group whose treatment sites and subsequent stent grafts were examined by contrast computed tomographic angiography before surgery, directly after surgery (within 4days), as well as 1year and 2years thereafter. We created curved planar reconstruction (CPR) images and measured the length of migration and neck angle using our method. At 2years after EVAR, the average length of proximal landing zone was 21.4±9.2mm. The average length of stent migration after 2 years was 1.41±2.68mm. The average neck angle was 33.9° preoperatively and 29.9° directly after surgery yielding a significant difference. However, 1 and 2 years after surgery the average neck angle was 28.2° and 28.4°, respectively. The number of patients experiencing a change >6° in the angle of the proximalneck between the preoperative condition and that directly after surgery was 16 (34.8%) with the use of Zenith stent grafts (n=46) and 14 (41.2%) with the use of Excluder stent grafts (n=34). There was no correlation between the proximal neck angle and migration of the proximal stent graft. In addition, there was no correlation between the changes in proximal neck angle and the secondary intervention rate and the occurrence of endoleak. There was a significant change in the neck angle between the preoperative condition and the immediate postoperative condition. However, there was no clear relationship found between the angle of the neck and the proximal stent-graft migration. Postoperative changes in the proximal neck angle just after EVAR and subsequent temporal changes during a 2-year follow-up period do not appear to predict stent-graft migration, secondary intervention rates, or the occurrence of endoleak.