Mesenteric ischemia: acute and chronic.

Acute mesenteric ischemia is a circulation-insufficiency event, occurring either suddenly or rapidly over a few weeks, that deprives one or several abdominal organs of adequate respiration to meet metabolic demands. Although mesenteric ischemia occurs infrequently, the mortality rate is from 60 to 100%, depending on the source of obstruction. The risk of atherosclerotic-related mesenteric occlusive disease increases with aging and those who have severe cardiovascular disease are at the highest risk. From 20 to 30% of hospital admissions for acute mesenteric ischemia are from nonocclusive mesenteric ischemia. Nearly 5 to 15% of all acute mesenteric ischemic cases are from a venous thrombosis.