Subclavian Steal Syndrome – Diagnosis

Etiology:  stenosis of (usually) L subclavian artery –> reversal of flow through the “vertebral artery loop” to supply blood to distal L subclavian.


  • Carotids:  bruits, pulse quality
  • Subclavians:  bruits, pulse quality, pulse delays
  • Vertebrals:  auscultate suboccipital region for bruits
  • Thoracic outlet syndrome:  Adson test (abduction and external rotation of arm causes decrease in radial pulse) – not a great test, high rate of false positives.
  • Blood pressure differential – >15 mmHg – affected side lower
  • Pulse differential (weaker or delayed on affected side)

Differential Diagnosis:

  • Atherosclerosis
  • Congenital
  • Tumor
  • Takayasu’s arteritis

Confirmatory:  U/S or CTA imaging.


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