A prospective study of anatomico-pathological changes in abdominal aortic aneurysms following endoluminal repair: Is the aneurysmal process reversed?

Aim: The aim of this prospective study was to analyse early anatomico-pathological changes in abdominal aortic aneurysms (AAA) following endoluminal repair to determine if the natural history of continued expansion of AAA is reversed. Materials and Methods: Sixty-seven of 85 patients undergoing endoluminal AAA repair between May 1992 and August 1995 had their operations prior to the end of February 1995 and were potentially available for follow up at 6 months or longer after operation. Excluded were: patients with failed endoluminal repairs (n = 14), patients who died within 6 months of operation (n = 5), patients with anastomotic AAA (n = 1), leaving 47 patients in the study group. Based on contrast enhanced CT performed preoperatively, within 10 days of operation and 6, 12 and 18 months after operation patients were divided into two groups: those in whom the AAA maximum transverse diameter (MTD) decreased Group I (n = 39) and those in which it increased Group II (n = 8). The following parameters were analysed: diameter of the supra coeliac aorta, MTD and the dimensions of the proximal and distal necks of the AAA plus extravasation ('leak') of contrast into the aneurysmal sac. Results: Leak of contrast was seen in 0 of 39 patients in Gp I and 5 of 8 patients in Gp II. Patients in Group I experienced a progressive diminution in AAA mean MTD. The diameters of the proximal and distal necks increased but there was no shortening of the length of the necks in this group. In Group II the AAA MTD was dependent on whether or not the aneurysmal sac was isolated from the circulation. The diameter of the proximal and distal necks increased irrespective of this fact. Conclusion: We conclude that in early follow up AAA which diminish in diameter following endoluminal repair remain isolated from the general circulation. Co-incident with this decrease in AAA diameter, the proximal and distal necks increase in diameter but do not undergo any shortening in length. This paradoxical increase in neck diameter was not progressive in the period of follow-up.