Visceral Artery Insufficiency

Chronic intestinal ischemia results from atherosclerotic occlusive lesions at the origins of the superior mesenteric artery (SMA), celiac artery, and inferior mesenteric artery (IMA). Because of collateral flow via the middle colic artery branch of the SMA and the ascending colic artery of the IMA, the superior and inferior pancreaticoduodenal arteries, and the superior and inferior hemorrhoidal arteries, bowel ischemia does not occur until two of the three main visceral arteries are diseased severely. In fact, almost 30% of patients with peripheral vascular disease have asymptomatic occlusive disease of the mesenteric arteries. Symptoms consist of postprandial epigastric pain, and at later stages, food avoidance (sitophobia), resulting in weight loss. Chronic intestinal ischemia is a diagnosis of exclusion, derived after a negative workup for peptic ulcer disease, gastroesophageal reflux, pancreatitis, irritable bowel syndrome, and malignancy. A suggestive history in a person over 45 years of age who appears chronically ill, has risk factors for arterial occlusive disease, and has no other identifiable cause for abdominal symptoms is an indication for arteriography. Intravenous hydration must be provided to avoid acute bowel ischemia from catheter-induced or contrast-associated arterial spasm. Surgical or endovascular management is directed toward restoration of antegrade visceral arterial flow. Transaortic endarterectomy and mesenteric artery bypass are associated with a 5-9% mortality rate and a 10-25% recurrence rate at long-term follow-up. A higher recurrence rate is observed with stenting of short-segment lesions; these patients require routine angiographic follow-up. Survivors have an unexpectedly good long-term life expectancy.

Celiac axis compression syndrome (stenosis of the celiac artery caused by external compression of the arcuate ligament) has been described as a variant of chronic mesenteric ischemia. As an isolated entity, it is occasionally associated with cramping abdominal pain, nausea, vomiting, and diarrhea. Division of the arcuate ligament may be combined with celiac artery dilation. The pathophysiological basis for this disease remains elusive.

Acute intestinal ischemia may result from (1) embolic occlusion of a visceral branch of the abdominal aorta, generally in patients with mitral valvular disease, atrial fibrillation, or left ventricular mural thrombus; (2) thrombosis of an atherosclerotic mesenteric vessel; (3) low-flow or shock state due to cardiac failure or arterial spasm induced by ergot or cocaine intoxication; or (4) postcoarctectomy syndrome, producing nonocclusive mesenteric vascular insufficiency. Emboli are responsible for almost half of all cases. Symptoms include sudden onset of severe epigastric and periumbilical abdominal pain with minimal appreciable findings on abdominal examination ("pain out of proportion to physical findings") and a high leukocyte count. Lactic acidosis, hypotension, and abdominal distention indicate bowel infarction. Mortality approaches 80% despite aggressive surgical management.