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.
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