Subclavian steal syndrome

Subclavian steal syndrome
Other names	Subclavian steal phenomenon or Subclavian steal steno-occlusive disease
The proximal part of left subclavian is blocked (shaded artery). This prevents antegrade ("forward") flow to the left arm and left vertebral. As a result, flow in the left vertebral is retrograde ("backwards") towards the left arm. Flow to the brain and circle of Willis is via antegrade right and left carotid and right vertebral arteries.
Specialty	Neurology

Subclavian steal syndrome (SSS), also called subclavian steal steno-occlusive disease, is a constellation of

• Presyncope
  (sensation that one is about to faint)
• Syncope (fainting)
• Neurologic
  deficits
• Blood pressure differential between the arms
• severe memory problems
• hands showing circulation problems (hands can have blotchy patches of red and white) (associated with other stigmata of
  fingers
  ).

Causes

There are multiple processes that can cause obstruction of the subclavian artery before the vertebral artery, giving opportunity for SSS.

Atherosclerosis is the most common cause of SSS;^[2] all atherosclerotic risk factors are risk factors for SSS.

Thoracic outlet syndrome (TOS) increases the risk for SSS.^[2] TOS doesn't directly cause SSS, because the site of subclavian artery compression is over the first rib, which is distal to the vertebral artery. TOS has been reported to cause stroke through theorized clot propagation towards the vertebral artery;^[3] a similar mechanism could explain how TOS causes SSS. Presence of a cervical rib is a risk factor for both TOS and SSS.^{[citation needed]}

Takayasu's arteritis is a disease causing inflammation of arteries, including the subclavian artery. Inflammation leaves behind dense scar tissue, which can become stenotic and restrict blood flow.^[4]

SSS can be

Various congenital vascular malformations cause SSS, examples including aortic coarctation and interrupted aortic arch.^[7]

Pathophysiology

Classically, SSS is a consequence of a redundancy in the circulation of the brain^[8][9] and the flow of blood.

SSS results when the short low resistance path (along the subclavian artery) becomes a high resistance path (due to narrowing) and blood flows around the narrowing via the arteries that supply the brain (left and right vertebral artery, left and right internal carotid artery). The blood flow from the brain to the upper limb in SSS is considered to be stolen as it is blood flow the brain must do without. This is because of collateral vessels.^{[citation needed]}

As in vertebral-subclavian steal,

The blood vessels supplying the brain arise from the vertebral arteries and internal carotid arteries and are connected to one another by communicating vessels that form a circle (known as the circle of Willis).^{[citation needed]}

Blood flow

Normally, blood flows from the aorta into the subclavian artery, and then some of that blood leaves via the vertebral artery to supply the brain.

In SSS a reduced quantity of blood flows through the proximal subclavian artery. As a result, blood travels up one of the other blood vessels to the brain (the other vertebral or the carotids), reaches the basilar artery or goes around the cerebral arterial circle and descends via the (contralateral) vertebral artery to the subclavian (with the proximal blockage) and feeds blood to the distal subclavian artery (which supplies the upper limb and shoulder).^{[citation needed]}

Diagnosis

The evaluation for this condition includes:^{[citation needed]}

• Doppler ultrasound
• CT angiography

Differential diagnosis

• Stroke

Treatment

Management for this condition includes:^{[citation needed]}

• Carotid subclavian bypass
• balloon angioplasty
• Endarterectomy

Additional images

See also

• Vascular access steal syndrome
• Peripheral artery disease

References