subclavian steal; reversed Robin Hood syndrome

Introduction

Occurs when the subclavian artery is blocked proximal to the origin of the vertebral artery. Exercise of arm may reverse blood flow in the ipsilateral vertebral artery & draw blood from the vertebrobasilar system. Symptoms of vertebrolasilar insufficiency may occur, but rarely, does significant ischemia of the vertebrobasilar system develop.

Etiology

• atherosclerosis
• Takayasu arteritis
• compression of the subclavian artery in the thoracic outlet
  • kinking or stenosis of subclavian artery as it goes over first rib (baseball pitchers, golfers)
• after surgical repair of coarctation of the aorta
• after surgical repair of tetralogy of Fallot with a Blalock-Taussig anatomososis
• congenital anomalies
  • right aortic arch with isolation of left subclavian artery
  • anomalies of the brachiocephalic arteries

Pathology

• subclavian artery is blocked proximal to the origin of the vertebral artery
• exercise of arm may reverse blood flow in the ipsilateral vertebral artery & draw blood from the vertebrobasilar system
• symptoms of vertebrolasilar insufficiency may occur, but rarely, does significant ischemia of the vertebrobasilar system develop
• anterograde flow in the basilar artery is present in most patients regardless of the flow pattern in the vertebral artery

Clinical manifestations

• ischemia of ipsilateral arm
  • claudication of arm
  • fatigue, coolness, paresthesias or numbness of arm
  • case presentation with chest pain & dizziness
• vertebrobasilar insufficiency
  • dizziness
  • ataxia
  • vertigo
  • diplopia
  • nystagmus
  • bilateral visual blurring
• difference in brachial artery systolic pressure > 15-20 mm Hg
  • systolic blood pressure difference of >= 15 mm Hg between right & left arms
• delay in arrival of radial artery pulse on affected side
• palpation/ausculation of carotids for carotid bruits, pulse
  • bruit over supraclavicular & lower carotid areas
• ausculation over suboccipital region for vertebral artery bruits

Radiology

• carotid ultrasound, doppler
  • include vertebrobasilar system
• magnetic resonance angiography
• contrast angiography

Complications

• embolism

Differential diagnosis

• thoracic outlet syndrome

Management

• low incidence of posterior circulation ischemic events
• may patients improve over time without treatment
• surgery
  • extrathoracic revascularization
    • common carotid as donor artery
  • axillo-axillary bypass
• percutaneous transluminal angioplasty in combination with stent placement
  • fewer complications than surgery
  • equally effective
• for patients with coexisting severe carotid stenosis, carotid endarterectomy should be done first
• for patients with emboli into the vertebrobasilar system
  • surgical repair of embolic source, or
  • anticoagulation

More general terms

• cerebral ischemia
• syndrome