Terminology

Preprocedure

Procedure

Definitions

• Acute mesenteric ischemia (AMI)
  • Life-threatening vascular emergency with 60-80% mortality
    • Mortality directly corresponds to diagnosis & treatment time
      • Mortality 39% when revascularization achieved < 12 h
      • Mortality 70% when time to diagnosis > 24 h
  • May be occlusive or nonocclusive in etiology
  • Clinical presentation of AMI
    • History may include atrial fibrillation, atherosclerotic disease, hypertension, myocardial infarction, postprandial pain, hypercoagulable or connective tissue disorder
      • Often older adult patients with significant comorbidities
    • Acute, severe, midabdominal pain disproportionate to physical examination
      • May have associated nausea & GI hemorrhage
      • May have peritoneal signs suggesting ischemia
    • Laboratory data: Leukocytosis, lactic acidosis, elevated liver enzymes
• Occlusive AMI
  • Arterial embolism
    • Cause of AMI in up to 50% of cases
    • Superior mesenteric artery (SMA) very susceptible because of high flow & acute takeoff from aorta
    • 50% of emboli lodge 6-8 cm beyond SMA origin, just distal to middle colic origin
      • Emboli lodge at bifurcation points, more distally as arterial caliber decreases
    • Etiology often from cardiac sources: Risk factors include acute myocardial infarction, arrhythmia, ventricular aneurysm, or valvular disease
    • Lack of collaterals results in poor distal SMA flow
    • Inferior mesenteric artery (IMA) less common site of occlusion due to lower flow & smaller lumen
  • Arterial thrombosis
    • Cause of AMI in ~ 25% of cases
    • Acute thrombosis of preexisting stenosis, occurring near SMA origin
    • Associated with previous postprandial pain & intestinal angina
    • Collateral vessel may be present due to chronic stenosis
    • Onset may be less acute vs. arterial embolism
    • Often worse prognosis than arterial embolism because of more proximal occlusion
  • Aortic dissection
    • Cause of AMI in < 5% of cases
    • Dissection flap extends into SMA
  • Miscellaneous etiologies
    • Trauma, retroperitoneal fibrosis, fibromuscular dysplasia, segmental arterial mediolysis, & vasculitis
• Nonocclusive AMI (NOMI)
  • Cause of AMI in 25% of cases
  • Associated with prolonged hypotensive event or vasopressors (e.g., digitalis, dopamine)
  • Other causes of NOMI include drugs (cocaine, digitalis), recent coarctation repair, & vasculitides
  • Diffuse vasospasm throughout SMA territory is characteristic
  • Delayed filling of superior mesenteric vein (SMV) occurs on imaging
• Mesenteric venous thrombosis
  • Cause of AMI in 5-10% of cases
    • May involve SMV &/or smaller venous branches
  • Associated with hypercoagulability, trauma, abdominal surgery, neoplasm, inflammatory bowel disease, oral contraceptives, or sepsis
• Chronic mesenteric ischemia (CMI)
  • a.k.a. intestinal angina
  • Chronic occlusion/stenosis of bowel arterial supply
    • Historically defined as occlusion/stenosis of ≥ 2 of 3 major mesenteric vessels (i.e., celiac, SMA, IMA)
    • Increasingly recognized that occlusion/stenosis of 1 of 3 major mesenteric vessels can result in CMI
  • Progression from CMI to AMI has > 50% mortality
  • Clinical presentation of CMI
    • Recurrent episodes of postprandial pain (dull, cramping) beginning shortly after eating & lasting 1-2 h in duration
    • 80% association with weight loss due to food aversion/fear of eating
    • Nonspecific nausea, vomiting, diarrhea
    • Relates to digestive demand for increased blood flow; perfusion restricted by occlusive process
  • Atherosclerotic CMI
    • Occurs more frequently in older women
    • Associated with peripheral vascular disease, coronary artery disease, smoking
    • May consider endovascular stent placement as 1st-line therapy
      • Especially for poor surgical candidates
      • Surgical options remain if endovascular treatment fails
  • Median arcuate ligament syndrome
    • Abdominal pain attributed to compression of celiac artery or ganglion by median arcuate ligament (fibrous arch formed by left & right diaphragmatic crura)
    • More common in women 20-40 years old
    • Symptoms may involve celiac ganglion compression
      • Worsened by stent placement
      • Should be surgically treated
    • Debatable whether this is CMI variant
  • Other causes of CMI
    • Arterial dissection, fibromuscular dysplasia, radiation

Indications

Contraindications

Preprocedure Imaging

Getting Started

Patient Position/Location

Procedure Steps

Alternative Procedures/Therapies

Things to Do

Things to Avoid

Problems

Complications

Expected Outcomes