Acute mesenteric ischemia

Arterial supply	Target organs
Celiac	Esophagus, stomach, proximal duodenum, liver, gallbladder, pancreas, and spleen
Superior mesenteric artery	Distal duodenum, jejunum, ileum, colon to the splenic flexure
Inferior mesenteric artery	Descending colon, sigmoid, and rectum

Table 39.2. Risk factors for subtypes of mesenteric ischemia

Etiology	Risk factor
Mesenteric arterial embolism	1. Coronary artery disease: postmyocardial infarction or ischemia2. Heart disease: congestive heart failure, cardiomyopathies, ventricular aneurysms3. Valvular disease: rheumatic heart disease, endocarditis4. Arrhythmias: atrial fibrillation and other atrial tachyarrhythmias5. Vasculature: aortic aneurysm, aortic dissection6. Coronary angiography
Mesenteric arterial thrombosis	1. Uncontrolled hypertension2. Cerebral, coronary, or peripheral vascular disease
Nonocclusive mesenteric ischemia	1. Cardiovascular: congestive heart failure, arrhythmias, cardiogenic shock2. Hypoperfusion: hypovolemic or septic shock3. Drugs: vasopressors, α-agonists, vasopressin, digoxin, cocaine
Mesenteric venous thrombosis	1. Hypercoagulable process: pregnancy, oral contraceptives, protein C, S, or antithrombin III deficiencies, polycythemia vera, sickle cell disease, malignancy, systemic lupus erythematosus2. Abdominal inflammatory conditions: diverticulitis, cholangitis, appendicitis, pancreatitis3. Trauma: abdominal injuries, venous injuries4. Other: portal hypertension, congestive heart failure, renal failure

The diagnosis should be considered in those older than 50 years, presenting with nonspecific abdominal pain and risk factors for the disease.
The physician must have a high index of suspicion as the history may be difficult to obtain.
Acute onset of severe poorly localized abdominal pain.
Often presents with vague complaints and pain out of proportion to the examination.
Nausea/vomiting and a history of intestinal angina.
Diarrhea due to cathartic stimulus of ischemia.
Gross or occult GI bleeding.
Peritonitis is a late finding and indicates severe bowel ischemia and necrosis.
Time is bowel: survival is 50% when diagnosed within 24 hours but drops to less than 30% after 24 hours.
Subtype presentations
- Clinical presentations of the subtypes of mesenteric ischemia are listed in Table 39.3.