Mesenteric ischemia

Background

• Most commonly SMA, thus typically involves small bowel (especially jejunum) and right colon
• Left colon uncommonly involved due to collateral flow

Pathophysiology

4 distinct entities:

1. Mesenteric arterial embolism (ex. Afib)
2. Mesenteric arterial thrombosis (ex. Vasculopath)
3. Nonocclusive mesenteric ischemia (ex. Hypovolemia from diuretics)
4. Mesenteric venous thrombosis (ex. hypercoagulable state)

Risk Factors for Mesenteric Ischemia Types

Type	Risk Factor
Arterial Embolism	Dysrhythmia (A. Fib) Valve Disease MI
Arterial Thrombosis	Atherosclerotic Disease
Venous Thrombosis	Prior thrombosis history Hypercoagulable state (preg, cancer, clotting disorder)
Nonocculsive	Hypovolemic state Heart Failure MI w/ dec output Sepsis Diuretic use

Epidemiology

• Mean age: 70yo
• 2/3 women

Risk Factors

• CAD
• Valvular heart disease
• Dysrhythmia
• Hypovolemia / hypotension
• Meds
  • Diuretics
  • Vasoconstrictive
  • Digoxin
• Dialysis

Clinical Features

• Pain out of proportion to exam. Abdomen often soft, without guarding.
  • Pain often L sided around watershed areas of colon (splenic flexure and recto-sigmoid junction)
• Severe, generalized, colicky
• Bloody stools

Differential Diagnosis

Colitis

• Infectious colitis
• Ischemic colitis
• Ulcerative colitis
• CMV colitis
• Crohn's colitis
• Toxic colitis (antineoplastic agents)
• Pseudomembranous colitis
• Fibrosing colonopathy (Cystic fibrosis)

Diffuse Abdominal pain

• Abdominal aortic aneurysm
  • Aortocaval fistula
• Acute gastroenteritis
• Aortoenteric fisulta
• Appendicitis (early)
• Bowel obstruction
  • Large bowel obstruction
    • Ogilvie's syndrome
  • Small bowel obstruction
  • Malignant bowel obstruction
• Bowel perforation
• Diabetic ketoacidosis
• Gastroparesis
• Hernia
• Hypercalcemia
• Inflammatory bowel disease
• Mesenteric ischemia
  • Mesenteric vein thrombosis
• Pancreatitis
• Peritonitis
• Sickle cell crisis
• Spontaneous bacterial peritonitis
• Volvulus

Diagnosis

• Labs
  • Lactate (higher later)
  • WBC (often >15K)
  • Chemistry (metabolic acidosis)
  • Hyperphosphatemia
• Upright or left lateral decub XR with intraabdominal air
• CTA
• Mesenteric angiography considered gold standard

Management

• IVF
• IV antibiotics - broad spectrum abx to prevent sepsis
• Narcotic analgesia

Acute arterial embolus

• Papaverine infusion (30-60 mg/h IV) OR
• surgical embolectomy OR
• intra-arterial thrombolysis

Nonocclusive mesenteric ischemia

• Papaverine infusion

Mesenteric venous thrombosis

• Heparin/warfarin either alone or in combination with surgery
• Immediate heparinization should be started even when surgical intervention is indicated
  • Decreases progression of thrombosis and improves survival

Chronic mesenteric ischemia

• Angioplasty with or without stent placement or surgical revascularization

Disposition

• Admit with consultation of one or more of the following
  • IR
  • Vascular
  • Surgery