Acute colorectal ischemia after aortic surgery: pathophysiology and prognostic criteria

Acute colorectal ischemia is a rare though potentially lethal complication of aortic surgery. We reviewed our recent experience with 16 cases in order to analyze its causative and prognostic factors. The incidence was 2.8%, and the inferior mesenteric artery was occluded in all cases. All patients also had severe occlusive disease of at least two of the hypogastric or deep femoral arteries. Hypoperfusion due to arterial ligation, prosthetic occlusion or embolism was responsible in half the cases. Ischemia and perfusion due to aortic cross-clamping or perioperative hemorrhage were involved in the rest of the cases. Postoperative mortality was 31%. The mortality was lower for partial, nontransmural necrosis, and for elective operations. Recurrent intestinal ischemia, transmural necrosis, surgery for ruptured aneurysm, intestinal hemorrhage and pulmonary edema were associated with a higher mortality rate. All patients with anuria or extrarenal epuration and hepatic cytolysis died. Although reconstruction of the inferior mesenteric artery might lessen the incidence of postoperative colonic ischemia due to hypoperfusion, the role of oxygen free radicals should be investigated in humans, in order to afford colonic protection against the consequences of ischemia-reperfusion.