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Abstract
cute mesenteric ischemia is a syndrome in which inadequate blood flow through the mesenteric circulation causes ischemia and eventual gangrene of the bowel wall. The syndrome can be classified generally as arterial or venous disease. Arterial disease can be subdivided into non -occlusive mesenteric ischemia (NOMI) and occlusive mesenteric arterial ischemia (OMAI).
Practically, AMI is divided into 4 different primary clinical entities: acute mesenteric arterial embolus (AMAE), acute mesenteric arterial thrombosis (AMAT), NOMI, and mesenteric venous thrombosis (MVT). OMAI includes both AMAE and AMAT.
Embolization to the SMA is the most frequent cause of AMI, responsible for approximately 30% to 50% of cases.
Clinical presentation of AMI is non-specific in most cases and can be characterized by an initial discrepancy between severe abdominal pain and minimal clinical findings. Physical examination does not reliably differentiate between ischemic and infarcted bowel. Complications such as ileus, peritonitis, pancreatitis, and gastrointestinal bleeding may also mask the initial signs and symptoms of AMI. The risk factors for AMI, and the clinical course, differ according to the underlying pathologic condition.In general, patients with SMA embolism or thrombosis have an acute onset of symptoms and a rapid deterioration in their clinical condition, whereas those with NOMI or MVT have a more gradual onset and a more protracted clinical course.Investigation for acute mesenteric ischemia:
• Fifty percent of cases of AMI found to have white blood cell count higher than 20,000/mm3.
• D-dimer has been found to increase within as little as 30 minutes from the onset of intestinal ischemia.
• The ability of the N-terminal region of human albumin to bind cobalt is decreased in the presence of thromboembolic occlusion SMA.
• Increased serum D-lactate levels may be an early indicator in intestinal ischemia.
Plain abdominal radiograph in acute mesenteric ischemia are non specific. Characteristic abnor-malities as thumb printing occur in less than 40% of patients.
Barium enema has no place in diagnoses of acute mesenteric ischemia and may compromise subsequent diagnostic tests.
Although Duplex examination of the mesenteric circulation is playing an increasingly valuable role in the evaluation of chronic mesenteric arterial occlusive disease, the technical difficulty of imaging the mesenteric vessels in patients with distended bowel loops has significantly limited the role of this modality in assessing patients with suspected AMI. Next, ultrasound evaluation may be limited by patient body habitus.