Mesenteric ischemia is caused by a reduction in intestinal blood flow, which most commonly arises from occlusion, vasospasm and/or hypoperfusion of the mesenteric vasculature. The clinical consequences can be catastrophic, including sepsis, bowel infarction, and death, making rapid diagnosis and treatment imperative.
Intestinal ischemia can be divided into acute and chronic, based upon the rapidity and the degree to which blood flow is compromised.
●Acute mesenteric ischemia refers to the sudden onset of intestinal hypoperfusion, which can be due to occlusive or nonocclusive obstruction of arterial or venous blood flow. Occlusive arterial obstruction is most commonly due to emboli or thrombosis of mesenteric arteries while occlusive venous obstruction is most commonly due to thrombosis or segmental strangulation. Nonocclusive arterial hypoperfusion is most commonly due to primary splanchnic vasoconstriction.
●Chronic mesenteric ischemia (also called intestinal angina) refers to episodic or constant intestinal hypoperfusion, which usually develops in patients with mesenteric atherosclerotic disease.
Chronic mesenteric ischemia involving the small intestine will be reviewed here. The anatomy of the mesenteric vasculature, acute mesenteric small intestinal ischemia, and colonic ischemia are discussed separately. (See "Acute mesenteric ischemia" and "Colonic ischemia".)