• Acute interruption of blood flow to small or large intestine
  
  
• Causes:
  
  
  • Arterial embolism
    • Superior mesenteric artery most commonly involved
  • Arterial thrombosis
  • Nonocclusive mesenteric ischemia
    • Low cardiac output state with diffuse mesenteric vasoconstriction
  • Mesenteric venous thrombosis  

• Risk Factors
  
  
  • Atrial fibrillation/flutter
  • Recent acute MI
    • Ventricular aneurysm
    • Cardiomyopathies
    • Valvular disease
  • Hypovolemia or hypotension (sepsis)
  • Coagulation disorders or malignancy
  • Pancreatitis
  • Portal hypertension/cirrhosis
  • Medications
    • Vasopressor medications
    • Beta-blockers
    • Digoxin
    • Diuretics  

• Clinical signs and symptoms
  
  
  • Severe abdominal pain out of proportion to physical exam
  • Pain initially of a visceral nature and poorly localized
  • Nausea
  • Vomiting
  • Diarrhea
  • GI bleeding may be present  

• Imaging
  
  
  • Plain abdominal radiographs (abnormal in 20-60% of cases)
    • Thumbprinting
      • Non-specific finding indicating intestinal wall edema with hemorrhage in the setting of acute mesenteric ischemia
    • Pneumatosis
    • Portal venous gas
    • Pneumoperitoneum
      • All are indicative of infarcted bowel
  • CT
    • Bowel wall  thickening from edema or hemorrhage
    • Lack of enhancement indicates infarction
    • Pneumatosis, portal venous gas, pneumoperitoneum
    • Intraluminal thrombus in involved vessel

Mesenteric Vascular Ischemia. Top CT image shows gas in portal venous system (blue circle); center image shows absence of contrast in superior mesenteric artery due to thrombosis of this vessel (blue arrow) [The patient also has a markedly dilated common duct, not related to mesenteric ischemia]; lower image shows extensive pneumatosis intestinalis (red arrows)

• Mesenteric angiogram
  • Can distinguish between arterial embolic and thrombotic causes of acute mesenteric ischemia
    

• Treatment
  
  
  • Mesenteric angiogram
    • Vasodilator therapy
    • Thrombectomy/Embolectomy
  • Surgery
    • Thrombectomy/Embolectomy
    • Arterial bypass
    • Resection of necrotic bowel
      
      
• Complications
  
  
  • Sepsis/septic shock
  • Multiple system organ failure
  • Death
    
    
• Mortality
  
  
  • 70-90% overall
  • From arterial embolism: 60-80%
  • From arterial thrombosis: 70-100%
  • From nonocclusive mesenteric ischemia: 40%
  • From mesenteric venous thrombosis: 25-30%