Acute mesenteric ischemia (AMI) is a syndrome in which inadequate blood flow through the mesenteric circulation causes ischemia and eventual gangrene of the bowel wall. Broadly, AMI may be classified either as arterial or venous disease.
Arterial disease may be subdivided into nonocclusive mesenteric ischemia (NOMI; see the image below) and occlusive mesenteric arterial ischemia (OMAI). OMAI may be further subdivided into acute mesenteric arterial embolus (AMAE) and acute mesenteric arterial thrombosis (AMAT). Venous disease takes the form of mesenteric venous thrombosis (MVT). Thus, for practical purposes, AMI comprises 4 different primary clinical entities: NOMI, AMAE, AMAT, and MVT.
CT scan (with contrast) of nonocclusive mesenteric ischemia with resulting bowel wall edema (arrows). The 4 types of AMI have somewhat different predisposing factors, clinical pictures, and prognoses. A secondary clinical entity of mesenteric ischemia occurs because of mechanical obstruction, such as internal hernia with strangulation, volvulus, intussusception, tumor compression, and aortic dissection. Occasionally, blunt trauma may cause isolated dissection of the superior mesenteric artery (SMA) and lead to intestinal infarction.
Because the 4 types of AMI share many similarities and a final common pathway (ie, bowel infarction and death, if not properly treated), they are discussed together.
In 1930, Cokkinis remarked, “Occlusion of the mesenteric vessels is apt to be regarded as one of those conditions of which the diagnosis is impossible, the prognosis hopeless, and the treatment almost useless.”[1] This quote indicates some of the extreme difficulties faced by physicians treating AMI. Symptoms are nonspecific initially, before evidence of peritonitis presents. Thus, diagnosis and treatment are often delayed until the disease is advanced.
Fortunately, since 1930, many advances have been made that allow earlier diagnosis and treatment. Whereas the prognosis remains grave for patients in whom the diagnosis is delayed until bowel infarction has already occurred, patients who receive the appropriate treatment in a timely manner are much more likely to recover.[2]
Arterial disease may be subdivided into nonocclusive mesenteric ischemia (NOMI; see the image below) and occlusive mesenteric arterial ischemia (OMAI). OMAI may be further subdivided into acute mesenteric arterial embolus (AMAE) and acute mesenteric arterial thrombosis (AMAT). Venous disease takes the form of mesenteric venous thrombosis (MVT). Thus, for practical purposes, AMI comprises 4 different primary clinical entities: NOMI, AMAE, AMAT, and MVT.
CT scan (with contrast) of nonocclusive mesenteric ischemia with resulting bowel wall edema (arrows). The 4 types of AMI have somewhat different predisposing factors, clinical pictures, and prognoses. A secondary clinical entity of mesenteric ischemia occurs because of mechanical obstruction, such as internal hernia with strangulation, volvulus, intussusception, tumor compression, and aortic dissection. Occasionally, blunt trauma may cause isolated dissection of the superior mesenteric artery (SMA) and lead to intestinal infarction. Because the 4 types of AMI share many similarities and a final common pathway (ie, bowel infarction and death, if not properly treated), they are discussed together.
In 1930, Cokkinis remarked, “Occlusion of the mesenteric vessels is apt to be regarded as one of those conditions of which the diagnosis is impossible, the prognosis hopeless, and the treatment almost useless.”[1] This quote indicates some of the extreme difficulties faced by physicians treating AMI. Symptoms are nonspecific initially, before evidence of peritonitis presents. Thus, diagnosis and treatment are often delayed until the disease is advanced.
Fortunately, since 1930, many advances have been made that allow earlier diagnosis and treatment. Whereas the prognosis remains grave for patients in whom the diagnosis is delayed until bowel infarction has already occurred, patients who receive the appropriate treatment in a timely manner are much more likely to recover.[2]
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