From the Guidelines
Subclavian steal syndrome involves collateral blood supply that develops when there is stenosis or occlusion of the subclavian artery proximal to the vertebral artery origin, with the primary collateral pathway involving retrograde flow through the vertebral artery, and additional collateral routes including the thyrocervical trunk, internal thoracic artery, and intercostal arteries. The condition is characterized by reversal of blood flow in the ipsilateral vertebral artery to supply the arm distal to the obstruction, effectively "stealing" blood from the posterior cerebral circulation 1. This compensatory mechanism can cause neurological symptoms like dizziness, vertigo, visual disturbances, and ataxia when blood is diverted from the brain to the arm during exertion. Some key points to consider in subclavian steal syndrome include:
- The primary collateral pathway involves retrograde flow through the vertebral artery, which connects to the basilar artery and then to the contralateral vertebral artery.
- Additional collateral routes include the thyrocervical trunk, internal thoracic artery, and intercostal arteries.
- These alternative pathways help maintain perfusion to the affected arm but may be insufficient during increased demand, such as during arm exercise.
- Treatment depends on symptom severity and may include endovascular stenting, surgical bypass, or endarterectomy to restore normal antegrade flow in the vertebral artery and eliminate the steal phenomenon 1. It is essential to consider the severity of symptoms and the presence of any clinical factors that may predispose to surgical morbidity or mortality when deciding on the best course of treatment for subclavian steal syndrome. In general, extra-anatomic carotid-subclavian bypass is reasonable for patients with symptomatic posterior cerebral or cerebellar ischemia caused by subclavian artery stenosis or occlusion, while percutaneous endovascular angioplasty and stenting is also a reasonable option for patients with symptomatic subclavian steal syndrome 1.
From the Research
Collateral Supply in Subclavian Steal Syndrome
The collateral supply in subclavian steal syndrome is a complex network of blood vessels that helps to maintain blood flow to the arm and brain. Some key points about the collateral supply in this condition include:
- The vertebral artery plays a crucial role in the collateral supply, as it provides blood flow to the arm at the expense of the vertebrobasilar system 2
- The subclavian artery stenosis or occlusion leads to the development of collateral circulation, which can include blood flow from the vertebrobasilar apparatus 2
- The collateral supply can help to alleviate symptoms of subclavian steal syndrome, but it can also lead to a range of clinical manifestations, including dizziness, vertigo, and blurred vision 3
- The management of subclavian steal syndrome depends on the severity of clinical symptoms, but can include medical treatment, endovascular therapy, and lifestyle modifications 3
Key Factors Influencing Collateral Supply
Some key factors that influence the collateral supply in subclavian steal syndrome include: