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

The inferior mesenteric artery (IMA) is the nutrient artery for the descend ing colon. Colon ischemia after repair of abdominal aortic aneurysm (AAA) c an be prevented by routine or elective revascularization of the IMA. In cas e 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 perform ed 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 unde rwent AAA repair at 11 vascular surgery centers. The IMA was occluded in 11 3 of these patients (51%). This study involves the other 110 patients (49%) with patent IMA. Study consisted of measuring residual systolic arterial p ressure in the IMA (IMAP) immediately after AAA repair. To compensate for b lood 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-cla mping of the IIA to obtain two corresponding indexes-i.e., P1 and P2, respe ctively. 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 < 0.001. Thes e findings show that cross-clamping of the IIA during AAA repair resulted i n a significant decrease in IMAP.