Changes in the Infrarenal Residual Aorta after Open Repair for Abdominal Aortic Aneurysm (AAA)

Background: In abdominal aortic aneurysm (AAA) repair, European and the United States' guidelines recommend performing proximal anastomosis as close to the renal arteries as possible. A long infrarenal residual aorta (IRA) raises concern about the risk of enlargement and aneurysmal formation in the future. There are no descriptions of proximal anastomosis in Japanese guidelines. Objective: To investigate the relationship between the length of the IRA and its long-term enlargement. Subjects: 100 patients who underwent open repair for AAA at our hospital between June 2002 and November 2016 were included. The mean age was 70.2±8.2 (SD) years, and the mean observation period was 8.5±3.3 years. Group S (n=24) consisted of patients whose IRAs were less than 2 cm in length, and Group L (n=76) consisted of patients whose IRAs were more than 2 cm in length. The preoperative diameter of the infrarenal aorta and the length and diameter of IRA in the immediately after surgery, in the early postoperative period (within 1 year), in the mid-term (2 to 9 years), and in the remote period (after 10 years) were measured. Results: There was no significant change in IRA diameter between preoperative and immediate postoperative periods. The preoperative diameter of the infrarenal aorta were 23.0 [21.0-26.0] mm in group S and 22.0 [20.0-24.5] mm in group L. There was no significant difference of the preoperative IRA diameter between the two groups. The IRA diameters in the postoperative period and thereafter were 22.0 [20.0-26.0] mm, 23.0 [21.0-27.0] mm, 24.0 [22.0-28.0] mm, 26.0 [23.3-32.8] mm in group L, showing a significant dilatation immediately after operation (p