Do internal iliac arteries contribute to vascularization of the descending colon during abdominal aortic aneurysm surgery? An intraoperative hemodynamic study.

The inferior mesenteric artery (IMA) is the nutrient artery for the descending colon. Colon ischemia after repair of abdominal aortic aneurysm (AAA) can be prevented by routine or elective revascularization of the IMA. In case of occlusion of the IMA, revascularization of the internal iliac artery (IIA) has been recommended but its effectiveness has never been documented. In this study, intraoperative hemodynamic monitoring of the IMA was performed to determine if the IIA contributed significantly to the region supplied by the IMA. From January 1998 to August 1999, a total of 223 patients underwent AAA repair at 11 vascular surgery centers. The IMA was occluded in 113 of these patients (51%). This study involves the other 110 patients (49%) with patent IMA. Study consisted of measuring residual systolic arterial pressure in the IMA (IMAP) immediately after AAA repair. To compensate for blood pressure variations, systolic pressure in the radial artery (RAP) was measured concurrently and the inferior mesenteric index (P) was calculated by dividing IMAP by RAP. Measurements were made before and during cross-clamping of the IIA to obtain two corresponding indexes-i.e., P1 and P2, respectively. Mean P1 and P2 were 0.61 (95% confidence interval, 0.8-0.4) and 0.58 (95% confidence interval, 0.55-0.61), respectively, with p