General Principles

• Acute mesenteric ischemia results from arterial (or rarely venous) compromise to the superior mesenteric circulation.
• Emboli and thrombus formation are the most common causes of acute mesenteric ischemia, although nonocclusive mesenteric ischemia from vasoconstriction can also give rise to the disorder.
• Ischemic colitis results from mucosal ischemia in the inferior mesenteric circulation during a low-flow state (hypotension, arrhythmias, sepsis, aortic vascular surgery), often in patients with atherosclerotic disease.¹ Vasculitis, sickle cell disease, vasospasm, and marathon running can also predispose to ischemic colitis.
• Chronic mesenteric ischemia is caused by atherosclerosis of all three major abdominal arteries leading to intermittent hypoperfusion.