Harvey's Garden

Subclavian steal syndrome

1 min read

Epidemiology

Etiology

Pathophysiology

  • Stenosis or occlusion of the proximal subclavian artery, usually due to atherosclerosis.
    • Stenosis is located proximal to the origin of the vertebral artery.
    • During arm exercise, the increased O2 demand leads to vasodilation in the arm.
    • Blood flows from the contralateral vertebral artery → basilar artery → retrograde down the ipsilateral vertebral artery → to the subclavian artery distal to the stenosis.
    • This “steals” blood from the posterior cerebral circulation (vertebrobasilar system).

Clinical features

  • Arm Symptoms (Ipsilateral to stenosis)
    • Arm fatigue, pain, claudication, or paresthesias with exertion.
    • Coolness or pallor of the affected arm.
  • Neurologic Symptoms (Vertebrobasilar insufficiency)
    • Triggered by ipsilateral arm exercise.
    • Sx include: Dizziness/vertigo, syncope, ataxia, diplopia, dysarthria.
  • Physical Exam
    • KEY FINDING: Systolic blood pressure discrepancy >15-20 mmHg between the arms (lower on the affected side).
    • Weakened or absent radial pulse in the affected arm.
    • A supraclavicular or subclavian bruit may be audible.

Diagnostics

  • Duplex ultrasonography: Best initial test. Can demonstrate stenosis and reversal of flow in the vertebral artery.
  • CT or MR Angiography (CTA/MRA): Confirmatory tests used to visualize the anatomy and plan for intervention.

Treatment

Graph View