Subclavian artery steal syndrome (SSS) is a syndrome in which there is partial or complete occlusive damage to the proximal segment at the beginning of the vertebral artery in the subclavian artery or cephalic trunk, causing retrograde blood flow in the affected vertebral artery into the distal segment of the affected subclavian artery due to siphoning (blood steal), resulting in ischemic episodes in the vertebrobasilar artery, and ischemia in the affected upper extremity.
I. Clinical manifestations
1. Symptoms
The most common symptoms, such as vertigo, light paralysis of limbs, sensory abnormalities, bilateral visual impairment, ataxia, diplopia, syncope, are more common in men than in women, and the age is more than 50 years. Rarely, intermittent claudication, dysphonia, dysphagia, tinnitus, convulsions, headache and mental disorders are also seen. A small number of patients may experience “tipping syndrome”, a sudden loss of muscle strength in the lower extremities and a fall, but there may be no impairment of consciousness and a rapid recovery. Some patients may have upper limb fatigue, aching, cold and abnormal sensation, etc. Very few of them may cause cyanosis or necrosis of the fingers.
2. Physical signs
Most of the radial artery pulsations on the affected side are weakened or disappeared, and some of the brachial artery or subclavian artery pulsations are also weakened or disappeared. The blood pressure of the affected upper limb is reduced, and the difference in systolic blood pressure between the two upper limbs is usually above 20 mmHg. A systolic murmur can be heard in the supraclavicular fossa.
II. Examination
1.Transcranial Doppler ultrasound (TCD)
To detect the blood vessels and blood flow in the neck, reverse blood flow signal of vertebral artery can be seen, and a bundle arm test should be performed on the affected side if the diagnosis is suspected.
2.Color Doppler ultrasound
The stenosis or occlusion at the beginning of the subclavian artery can be seen, with flow disturbance and increased flow velocity at the stenosis, and the artery distal to the stenosis becomes low resistance; the flow of the vertebral artery is reversed, and the beam-arm test can increase the positive detection rate.
3.CT angiography (CTA) or magnetic resonance angiography (MRA)
This is the preferred method, which can reveal atherosclerotic plaque in the wall of the subclavian artery proximal to the beginning of the vertebral artery, narrowing or occlusion of the lumen, and provide a comprehensive understanding of the morphology of the aortic arch and its main branch arteries.
III. Treatment
There are two major types of surgical treatments in common use: percutaneous transluminal angioplasty and various extra-anatomical bypasses.
1.Percutaneous transluminal angioplasty stent placement (PTA)
A balloon catheter is delivered via percutaneous puncture to the stenosis or occlusion of the subclavian artery, and the balloon is expanded to reconstruct the arterial lumen, and stenting is feasible to prevent elastic retraction and arterial entrapment. It is suitable for stenotic subclavian artery steal syndrome.
2.Extra-anatomical bypass reconstruction
For occlusive type or severe stenosis, autologous saphenous vein or artificial vessel bypass, including carotid artery-subclavian artery, subclavian artery-subclavian artery, axillary artery-axillary artery bypass diversion, etc.
3.For elderly patients with atherosclerosis
Anticoagulation or anti-platelet aggregation agents can be administered to reduce thrombosis and development. For rare cases caused by giant cell arteritis, steroid treatment can be used.