A 56 year old man is brought to the emergency depament with rapid onset of severe abdominal pain. But physical examination seemed to be out of propoion to his symptom. Acute mesenteric ischemia was diagnosed. What is the MOST common cause of acute mesenteric ischemia?

Acute mesenteric ischemia occurs when prolonged reduction in the splanchnic blood flow occurs. The most common cause is aerial embolism, which accounts for 50% of cases. The emboli most commonly originate from a cardiac source. Most emboli lodge in the superior mesenteric aery (SMA) because of the angle from which it takes off from the aoa. Risk factors for developing the mural thrombi that embolize to the mesenteric aeries include, Myocardial ischemia/infarction Atrial arrhythmias (specifically atrial fibrillation and atrial flutter) Valvular disorders Cardiomyopathies Endocarditis Ventricular aneurysms Ref: Travis A.C., Saltzman J.R. (2012). Chapter 161. Small Bowel Disorders. In G.V. Lawry, S.C. McKean, J. Matloff, J.J. Ross, D.D. Dressler, D.J. Brotman, J.S. Ginsberg (Eds), Principles and Practice of Hospital Medicine.