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Case Fifty One - Acute Mesenteric Ischemia

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Clinical History: Two companion cases are presented. Patient #1 (Fig.1) is a 63-year-old woman status post aortic valve replacement who presents with a one week history of abdominal pain becoming quite severe over the last 24 hours. The patient also has guaiac positive stools and elevated white blood cell count. Patient #2 (Images 2-4) is an 85-year-old woman who presents with acute epigastric pain.

Findings: Figure 1 (Patient 1) demonstrates acute occlusion of the superior mesenteric artery just distal to the initial jejunal branches. The occlusion has a convex margin compatible with an acute embolus. Figures 2-4 (Patient #2) demonstrates a beaded appearance to the branches of the superior and inferior mesenteric arteries and celiac axis. Additionally, the ileal and right colonic branches of the superior mesenteric artery do not fill at all. Of note, patient #2 also had an accessory right hepatic artery off the superior mesenteric artery.

Diagnosis: Acute mesenteric ischemia.

Discussion: Acute mesenteric ischemia is best categorized as either occlusive or nonocclusive. Occlusive mesenteric ischemia may be on the basis of atherosclerotic disease (in which case it is often chronic in nature presenting with intestinal angina), dissection or emboli. Emboli may have many sources, including valve prostheses (as in this case), thrombi in the cardiac chambers, ulcerated atherosclerotic plaques, or even angiographic catheters. While thrombolytic therapy may be used on occasion, surgical embolectomy is often necessary given the limited time span in which the bowel can be successfully revascularized. Exploration also allows direct visualization of the bowel and removal of already necrotic loops.

Nonocclusive mesenteric ischemia (Patient #2) is usually on the basis of a low flow state secondary to poor cardiac output, hypovolemia or shock states. The beaded and irregular appearance of the mesenteric vessels is secondary to vasospasm. This can often be reversed with an infusion of a vasodilator such as Papaverine. However, in this case, the absence of flow to the ileum and right colon was consistent with a more advanced stage of bowel ischemia and the patient underwent exploration and bowel resection.

References:
Rueter SR, Redman HC, Cho KJ. Gastrointestinal Angioaphy. Saunders, 1986.

Johnsrude IS, Jackson DC, Dunnick NR. A Practical Approach to Angiography .
Little, Brown, 1987.

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Submitted by:
Peter J. Sachs, M.D.