Narrowing of the arteries that supply blood to the intestine causes mesenteric ischemia. These arteries arise directly from the aorta, which is the main artery from the heart that supplies oxygenated blood to the entire body. This problem is often seen in patients with atherosclerotic arterial disease (hardening of the arteries) elsewhere, such as patients with coronary artery disease, or peripheral vascular disease. It is more common in smokers and in patients with elevated serum cholesterol levels.

Alternatively, mesenteric ischemia may be caused by a blood clot (embolus), which travels through the bloodstream and suddenly blocks one of the mesenteric arteries. The source of these clots is usually the heart or the aorta. Such an embolus is seen more commonly in patients with heart arrhythmias such as atrial fibrillation, which predisposes patients to formation of clots within the chambers of the heart. With the beating of the heart, these clots break loose and can travel to the arteries of the intestine.

Chronic mesenteric ischemia caused by atherosclerosis is commonly associated with chronic abdominal pain after eating, and occasionally, diarrhea. Acute mesenteric ischemia due to an embolus is frequently associated with sudden-onset severe abdominal pain, vomiting, and diarrhea.

Laboratory tests may show an elevated white blood cell (WBC) count and acidosis in the case of acute mesenteric ischemia. A CT scan may show abnormalities of the vessels and the intestine. A mesenteric angiogram, a test in which dye is injected into the arteries of the intestine and x-rayed, is usually done. This can reveal the location of the blockage in the artery.

Treatment of chronic mesenteric ischemia usually requires surgery. The blockage in the involved arteries is removed, and the arteries reconnected to the aorta. Alternatively, a bypass around the blockage, usually with a prosthetic plastic tube graft, is performed.

Acute mesenteric ischemia is a surgical emergency. An operation is performed, and the clot removed from the artery. In some cases, a bypass must also be performed.

As an alternative to surgery, sometimes a stent may be inserted to enlarge the blockage of the mesenteric artery. This is a new technique, and should only be performed by experienced physicians.

In the case of chronic mesenteric ischemia, the outlook after a successful surgery is good. However, if appropriate lifestyle changes are not made, patients generally will suffer from progression of their atherosclerotic disease in the heart or other arteries over the long term.

Acute mesenteric ischemia often has a poor prognosis, since death of the intestine often occurs before surgical intervention is accomplished. However, when diagnosed and treated early, patients with acute mesenteric ischemia can be treated successfully.

Infarction (tissue death from lack of blood flow) of the intestines is the most serious complication of mesenteric ischemia.

Call your physician for any severe abdominal pain, fevers, nausea, vomiting, or changes in bowel habits.

Smoking cessation, dietary modification, exercise, and blood pressure control are all required for prevention of atherosclerotic disease. Control of heart arrhythmias is an important preventive measure for acute embolic mesenteric ischemia.