Subclavian Steal Syndrome Flashcards
What is Subclavian steal syndrome
A rare condition causing syncope or neurological deficits when the blood supply to the affected arm is increased through exercise.
What is SSC secondary to?
Proximal stenosing lesion or occlusion in the subclavian artery
This is typically on the left
What is the stenosis usually caused by?
Atherosclerosis
Can also be caused by vasculitis, TOS, complications of aortic coarctation repair
Pathophysiology
In order to compensate for the increased oxygen demand in the arm, the blood is drawn from the collateral circulation.
This results in reversed blood flow in the ipsilateral vertebral artery.
This means that the syndrome comprises of both cerebral and upper limb clinical features.
Epidemiology
M 2:1 F
Three times more likely to occur in left than right
What is Coronary-SSC
In patients who have undergone internal mammary artery IMA graft
There is an increase in oxygen demand in the left are which steals blood from the IMA leading to cardiac ischaemia
Risk factors
Atherosclerosis
Increasing age
Hyperlipidaemia
HTN
Smoking
DM
Clinical features
In periods of arm activity…
Reversal of blood supply to the posterior cerebral circulation by vertebral artery can lead to…
Vertigo, diplopia, dysphagia, dysarthria, visual loss, syncope
Arm claudication + arm pain or paraesthesia can happen as well
Investigations
Initial = Duplex US scan that can show retrograde flow
Routine CXR can show any external compression
Definitve ix is CT angiography or MR which will identify the anatomy of the occlusive lesion in the arm and can also help to assess the cerebral vasculature.
Risk scoring in SSC
Pre-subclavian steal = Purely a reduced anterograde vertebral flow
Intermittent alternative flow = Antegrade flow occurs in diastolic phase and retrograde in systolic
Advanced disease = permanent retrograde flow
Conservative management
All patients should be started on anti-platelet and statin therapy if suitable
Lifestyle advice with smoking cessation, weight loss and optimising diabetic control.
Surgical approaches
Percutnaeous angioplasty
Bypass
Explain percutnaeous angioplasty
Might also involve stenting
It has a success rate of 90% but higher rate of restenosis
Explain bypass
Done in longer or distal occlusions
Carotid subclavian bypass or axillo-axillary bypass can be done.
