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KEY POINTS

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  • Acute mesenteric ischemia is an infrequent but deadly clinical entity. When diagnosis is delayed, it is almost always fatal; therefore, a high index of suspicion is required, especially in those at high risk: the elderly, those with cardiac dysfunction, patients with diffuse atherosclerosis, and those following aortic and cardiac surgery or arterial catheterization.

  • The etiology of acute mesenteric ischemia may be embolic, thrombotic, primary vasoconstrictive, or secondary to venous thrombosis. Chronic ischemia is usually due to flow-limiting lesions (mesenteric stenosis or occlusions) in the presence of inadequate collateralization.

  • Classic symptoms of acute intestinal ischemia are central abdominal pain (often out of proportion to the benign abdominal examination), weight loss (an important clue even in the acute presentation), bowel emptying, and altered bowel function (vomiting, bloating, constipation, or diarrhea). Once signs of peritonitis or bloody diarrhea are present, shock, sepsis, and death almost always follow.

  • Arterial phase abdominal and pelvic computed tomographic (CT) mesenteric angiography is the investigation of choice, offering accurate diagnostic evaluation. However, selective mesenteric angiography offers therapeutic options, whereas duplex ultrasonography may not be definitive. Frequently, the diagnosis is confirmed only at laparotomy.

  • Treatment is most commonly surgical, with restoration of flow by embolectomy, bypass, or angioplasty (antegrade or retrograde); vasodilator infusion therapy; thrombolysis and resection of nonviable intestine; and liberal use of “second look” laparotomy.

  • Nonocclusive mesenteric ischemia (NOMI) has a high mortality rate, and early diagnosis and treatment are important for improving survival in patients with this condition.

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Acute mesenteric ischemia is a relatively rare but often fatal clinical entity. Although little data exist on its true incidence, data from the Swedish Vascular Registry suggest that it may account for just 1% of reconstructions for acute thromboembolism.1 Contemporary series, however, continue to report a mortality rate of between 32% and 48%.2,3 Although autopsy studies suggest that atherosclerosis affecting the mesenteric arteries is common (6%-10%),4 symptomatic mesenteric occlusive disease is rare. However, of patients presenting with acute mesenteric ischemia, one large series found that 43% had prior symptoms of chronic mesenteric ischemia.5 The spectrum of mesenteric ischemia includes occlusive disease secondary to atherosclerotic occlusion with thrombosis, embolism, mesenteric venous thrombosis, and nonocclusive mesenteric ischemia due to vasospasm (Table 109-1). At its most florid, it may present with mesenteric infarction, intestinal perforation, and septic circulatory collapse. This relatively rare but often fatal clinical entity must be considered early in the differential diagnosis of any patient with abdominal symptoms or signs but especially those with pain out of proportion to physical findings. Also a history of intestinal angina, peripheral vascular disease, cardiac dysfunction, aortic surgery or recent aortic catheterization, hypotension, or prothrombotic state increases the risk of mesenteric vascular disease. Noninvasive tests for mesenteric ischemia lack specificity and sensitivity, which mandates that the diagnosis often requires a high index of suspicion, supplemented by a liberal use of computed tomographic angiogram (CTA) when uncertainty remains. Where doubt exists in the ...

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