Subclavian Steal Syndrome
When a blocked arm artery diverts blood flow from the brain
Quick Facts
- Type: Blood vessel (vascular) condition
- Cause: Narrowed subclavian artery
- Key clue: Different blood pressure in each arm
- Symptoms: Dizziness, arm fatigue with use
Overview
Subclavian steal syndrome is a circulation problem that happens when the subclavian artery, the main blood vessel supplying an arm, becomes narrowed or blocked before it branches off to the brain. To make up for the reduced flow, blood is drawn backward down a vertebral artery that normally feeds the brain. In effect, the arm "steals" blood from the brain's circulation, especially when the arm is being used.
Many people with the underlying narrowing have no symptoms. When symptoms occur, they often involve brief dizziness during arm activity or arm fatigue and are usually not dangerous, but they signal significant artery disease that should be evaluated and managed.
Symptoms
Symptoms are often triggered by using the affected arm, which increases its demand for blood. They may include:
- Dizziness or lightheadedness, especially when using the arm
- Brief visual disturbances or double vision
- Problems with balance or unsteadiness
- Arm fatigue, aching, or weakness with activity
- Coolness, numbness, or paleness of the affected arm or hand
- A noticeable difference in pulse or blood pressure between the two arms
Because some symptoms overlap with those of a stroke or mini-stroke, sudden or severe symptoms such as one-sided weakness, slurred speech, or facial drooping should be treated as an emergency by calling emergency services.
Causes
The underlying cause is narrowing or blockage of the subclavian artery before the branch to the brain. Common reasons include:
- Atherosclerosis: A buildup of fatty plaque that narrows the artery, the most common cause.
- Inflammation of the arteries: Certain conditions that inflame blood vessels.
- Compression of the artery: From nearby structures in some cases.
- Previous injury or surgery: Affecting the artery.
The narrowing more often affects the left side, where the anatomy makes it more common.
Risk Factors
- Older age
- Smoking
- High blood pressure
- High cholesterol
- Diabetes
- Known atherosclerosis or peripheral artery disease elsewhere in the body
Diagnosis
A key clue is a difference in blood pressure between the two arms. Tests help confirm the narrowing and the reversed blood flow.
- Blood pressure comparison: Measuring pressure in both arms.
- Doppler ultrasound: Shows blood flow direction in the arteries, including any reversal.
- CT or MR angiography: Detailed imaging of the arteries to locate the narrowing.
- Catheter angiography: Sometimes used to map the blood vessels precisely, especially before treatment.
Treatment
Treatment depends on symptoms and the degree of narrowing. People without symptoms often need only management of cardiovascular risk factors.
- Risk factor management: Controlling blood pressure, cholesterol, and diabetes, and stopping smoking.
- Medications: Such as those used to reduce the risk of clots and treat atherosclerosis, as advised by a clinician.
- Angioplasty and stenting: A minimally invasive procedure to open the narrowed artery for significant symptoms.
- Surgery (bypass): Rerouting blood flow around the blockage in selected cases.
The goal is to relieve symptoms and reduce the broader risk associated with artery disease.
Prevention
- Do not smoke, and seek help to quit if you do
- Keep blood pressure, cholesterol, and blood sugar well controlled
- Eat a heart-healthy diet and stay physically active
- Maintain a healthy weight
- Attend regular checkups, especially if you have other artery disease
These steps slow atherosclerosis, the main process behind the condition.
When to See a Doctor
See a clinician if you notice dizziness when using one arm, arm fatigue or weakness with activity, or a coolness or color change in one hand. A blood pressure difference between your arms also warrants evaluation. Call emergency services immediately for sudden one-sided weakness, facial drooping, slurred speech, severe dizziness, or vision loss, which may signal a stroke.
Frequently Asked Questions
What is subclavian steal syndrome?
It is a circulation problem in which a narrowed artery supplying an arm draws blood backward from an artery that normally feeds the brain. This can cause dizziness or arm symptoms, especially when the affected arm is being used.
What is the main sign of subclavian steal syndrome?
A characteristic clue is a noticeable difference in blood pressure or pulse between the two arms. Other signs include dizziness during arm use and arm fatigue or weakness with activity.
Is subclavian steal syndrome dangerous?
Many people have the underlying narrowing without symptoms, and symptoms when present are often mild. However, it reflects significant artery disease that raises cardiovascular risk, so it should be evaluated. Sudden stroke-like symptoms are an emergency.
How is subclavian steal syndrome treated?
Treatment ranges from managing risk factors such as blood pressure, cholesterol, and smoking, to procedures like angioplasty with stenting or bypass surgery for significant symptoms. The approach depends on how much the condition affects you.
When should I seek emergency care?
Call emergency services right away for sudden one-sided weakness, facial drooping, slurred speech, severe dizziness, or vision loss. These can be signs of a stroke and need immediate treatment.
References
- MedlinePlus, U.S. National Library of Medicine. Atherosclerosis.
- National Heart, Lung, and Blood Institute (NHLBI). Atherosclerosis.
- American Heart Association. Peripheral Artery Disease.
- Mayo Clinic. Peripheral artery disease (PAD).