Abdominal aortic aneurysm neck remodeling after open aneurysm repair

Abstract

Proximal endovascular aortic graft fixation and maintenance of hemostatic seal depends on the long-term stability of the aortic neck. Previous investigations of aortic neck dilation mostly focused on the infrarenal aortic diameter. Fenestrated and branched stent grafts facilitate suprarenal graft fixation and may thereby improve the long-term integrity of the aortic attachment site. For these devices, the natural history of the suprarenal aortic segment is also of interest. We investigated the natural history of the supra- and infrarenal aortic segment after open abdominal aortic aneurysm (AAA) repair. For this retrospective analysis, we reviewed the preoperative and the initial postoperative as well as the most recent CT series that were obtained from 52 patients undergoing conventional repair of an infrarenal abdominal aortic aneurysm between January 1998 and December 2002. Measurements were performed using electronic calipers on a "split screen", allowing direct comparison of subsequent CT series at corresponding levels along the vessel. Main outcome measures were changes in postoperative measures of the supra- and infrarenal aortic diameters. The first postoperative exam was at a mean (+/-SD) of 7.0 +/- 3.5 months, and the final exams were at 44.4 +/- 21 months. Over this time period, the estimated rate of change in suprarenal diameter was 0.18 mm/ y with 95% confidence interval (CI) from 0.08 to 0.27. The estimated rate of change for the infrarenal diameter was 0.16 (95% CI: 0.05 to 0.27). A clinically relevant diameter increase of >or=3 mm was observed in seven patients (13%). There was evidence of larger diameter increases associated with larger AAA diameters (P = .003 and <.001 for suprarenal and infrarenal diameters), an inverted funnel shape (P = .002 and <.001), and marginal evidence of association with a history of inguinal hernia (P = .043 and .066). Although there is statistically significant evidence of increases in the supra- and infrarenal aortic diameters after conventional AAA repair, mean annual increases tended to be small and clinically relevant increases of 3 mm or more were observed in only a small proportion of cases.