Inferior Mesenteric Arterial Patterns

The importance of lesions of the segment of the gut supplied by the inferior mesenteric artery is hardly reflected by the volume of literature concerning this vascular bed. Over 75 per cent of all polyps and cancers of the colon occur in the area of distribution of this artery. Recent fragmentary studies suggest the possibility of identifying some of these lesions by arteriographie technics, and of differentiating them from inflammatory masses which simulate neoplasms (27). In the study of infarction of the bowel, emphasis traditionally has been on the superior mesenteric artery (29), which is a more common site of mesenteric thrombosis. Nevertheless, it is abundantly clear that the inferior mesenteric artery is also a frequent site of atheromatous change, and at times of occlusion. Perhaps a major factor in the persisting viability of the gut associated with significant disease of the inferior mesenteric artery is the richness of the collateral system. The inferior mesenteric artery itself serves as a collateral system, at times supplying blood to the lower extremity in the presence of thrombo-obliterative disease at the aortic bifurcation (19). Under these circumstances, it is possible severely to compromise the collateral circulation to the left lower extremity by left colectomy when the inferior mesenteric artery is a major source of blood supply to this area. At least one case is on record in which gangrene followed such a procedure (23). Although the anatomy of the inferior mesenteric artery in cadavers has been well described (12, 13, 26, 28), a serious and systematic attempt to analyze the angiographic anatomy and the variations therein has not hitherto been undertaken. Such a study seemed warranted not only because of the interest in inferior mesenteric artery insufficiency, but also because the future application of chemotherapeutic agents to bowel tumors by direct perfusion depends on a precise knowledge of the anatomy of their vascular bed. Furthermore, on the basis of previous experience, there is reason to believe that angiographic studies in vivo can yield information not attainable on postmortem studies and not necessarily in concord with conventional anatomic data (6). This study was undertaken, then, to analyze normal patterns, variations in the normal, and aberrations from the normal in the inferior mesenteric arterial circulation. Methods and Materials One hundred and forty-two consecutive angiographic studies of the abdominal aorta and its branches were reviewed. Percutaneous transfemoral or transaxillary catheter insertion was employed in all cases. With intra-aortic injection, a total volume of 35 to 40 c.c. of 76 per cent Renografin was injected over a two-second period. When selective mesenteric inferior arteriography was performed, 10 c.c. of 76 per cent Renografin was injected during a period of one and a half seconds.