Colonic ischemia: the Achilles heel of ruptured aortic aneurysm repair

Colonic ischemia is an often fatal complication of abdominal aortic aneurysm (AAA) repair. In elective AAA repair, patency of the inferior mesenteric artery (IMA) has been shown to be an important contributing factor. The purpose of this study was to determine which clinical and operative factors are important in the development of colonic ischemia in ruptured AAA repair. A retrospective review of all patients treated for ruptured AAA over a 7-year period was performed. Of 101 patients who were treated for ruptured AAA, 71 (70 per cent) survived for longer than 24 hours postoperatively, and these patients are the basis for this study. Colonic ischemia, primarily left sided, was a common perioperative complication (n = 24; 35 per cent) requiring colectomy in 11 patients (44 per cent). It carried a 44 per cent mortality compared to 20 per cent in patients without this complication (P = 0.07). Colonic ischemia occurred more frequently in patients with preoperative shock (P = 0.01) and a greater intraoperative blood loss (P = 0.003), but showed no correlation with patient age, co-morbid medical conditions, laboratory values, time to operation, or treatment of the IMA. Most patients with postoperative bowel ischemia were found to have chronic IMA occlusion, including 8 of the 11 patients requiring colectomy. Revascularization would not be feasible in this group. Revascularization of patent IMAs had little effect on outcome. Of the 17 patent IMAs, 9 were reimplanted and 5 (55 per cent) developed bowel ischemia, two of which required colectomy. Eight were ligated and 3 (38 per cent) developed bowel ischemia, one requiring colectomy. The presence of preoperative shock is the most important factor predicting the development of colonic ischemia following ruptured AAA. The incidence of ischemia is not altered by the presence of a patent IMA or with attempts at IMA revascularization. Colonic ischemia remains a significant source of morbidity and mortality in these patients.