Mesenteric Ischemia

Snapshot

• A 65-year-old gentleman presents with acute onset severe abdominal pain. The pain is described as “diffuse” without localization and constant. The patient states that he has had nausea and vomitting with this episode. Physical examination shows absent bowel sounds, mild abdominal distention, and pain that is disproportionate to the exam findings.  

Introduction

• Clinical definition
  • medical condition where the small intestine is injured secondary to any process that reduces intestinal blood flow
  • acute mesenteric ischemia
    • characterized by acute onset of severe abdominal pain and is associated with high risk of mortality
  • chronic mesenteric ischemia
    • gradual decrease of blood flow typically associated with atherosclerosis
    • characterized by postprandial abdominal pain with unintentional weight loss, food aversion, and vomiting
• Epidemiology
  • demographics
    • most commonly affects people > 60 years of age
  • risk factors
    • atrial fibrillation
    • heart failure
    • chronic kidney failure
    • hypercoagulable states
    • previous myocardial infarction
• Pathogenesis
  • can be due to a variety of processes
    • acute mesenteric ischemia is most commonly caused by an embolism in the main mesenteric artery
    • chronic mesenteric ischemia is most commonly caused by atherosclerosis 
  • arterial occlusion
    • embolism secondary to atrial fibrillation, myocardial infarction, or valvular disease 
    • thrombosis secondary to artherosclerosis
  • non-occlusive arterial disease
    • splanchnic vasoconstriction
    • hypoperfusion due to hypotension
• venous thrombosis

Presentation

• Acute mesenteric ischemia  
  • symptoms 
    • sudden onset of severe abdominal pain
    • nausea
    • diarrhea
    • vomiting
    • gastrointestinal bleeding
  • physical exam
    • fever
    • tachycardia
    • abdominal pain out of proportion to physical findings
    • peritoneal signs if bowel infarction
• Chronic mesenteric ischemia
  • symptoms
    • post-prandial abdominal pain that resolves (e.g., “intestinal angina”)
    • nausea
    • food aversion
    • vomiting
    • gastrointestinal bleeding
  • physical exam
    • weight loss
• abdominal bruit

Imaging

• Mesenteric angiography 
  • gold standard for arterial occlusive disease
  • allows for differentiation of the different etiologies and direct infusion of vasodilators in the setting of nonocclusive ischemia  
• Computed tomography (CT) with angiography 
  • best initial imaging
  • will elucidate other causes of abdominal pain
  • findings may include mesenteric edema, bowel dilatation, bowel wall thickening, intramural gas, and mesenteric stranding
• Abdominal radiograph
  • can rule out other causes of abdominal pain
• images will often appear normal

Studies 

• Laboratory studies
  • leukocytosis
• elevated lactic acid 

Differential

• Ischemic colitis 
  • differentiating factors
    • will demonstrate pathology of the large bowel on imaging
• Perforated viscus
  • differentiating factors
• visualization of gas on abdominal radiograph

Treatment

• Therapy is dependent on the etiology and can be pharmacological or surgical
• Non-occlusive mesenteric ischemia
  • IV fluid resuscitation
  • nasogastric tube decompression
  • anti-coagulation regimen (as needed)
  • vasodilator (e.g. papaverine)
• Occlusive mesenteric ischemia
  • surgical revascularization via angioplasty
  • thrombolytic therapy
• Emergency laparotomy       
  • indicated if evidence of bowel infarction/necrosis or peritonitis
• may require bowel resection

Complications

• Sepsis
• Death
• Bowel necrosis
• Perforation