Subclavian steal syndrome is characterized by abnormal blood flow in the arteries. The condition has many potential causes, some of which can be serious without proper treatment.
Subclavian steal syndrome affects the artery that supplies blood to the neck and head or the arteries that supply blood to the arms. Because of this, people may experience symptoms in these areas.
However, many people with the condition do not experience any symptoms at all.
This article describes what subclavian steal syndrome is and lists some of its potential symptoms and causes. It also provides information about the risk factors for subclavian steal syndrome, along with some advice on treatment and management.
Arteries are blood vessels that carry blood away from the heart, toward other parts of the body.
The term antegrade blood flow describes blood that is flowing away from the heart. The term retrograde blood flow describes blood that is flowing toward the heart.
Subclavian steal syndrome is the medical term for a group of signs and symptoms that indicate retrograde blood flow in an artery.
Some cases of subclavian steal syndrome involve retrograde blood flow in the vertebral artery. This artery runs along a person’s neck, supplying blood to the neck and head. Having subclavian steal syndrome of the vertebral artery means that some amount of blood will be moving away from the neck and head.
Subclavian steal syndrome can also affect the arteries that carry blood toward a person’s arm.
According to a 2019 report, experts estimate that subclavian steal syndrome affects between 0.6% and 6.4% of the general population.
Subclavian steal syndrome can vary in severity. Doctors classify the condition according to the extent to which it disrupts blood flow.
The list below outlines the different classifications:
- Grade 1 (pre-subclavian steal syndrome): Grade 1 describes reduced antegrade blood flow in the affected artery.
- Grade 2 (intermittent or partial subclavian steal syndrome): Grade 2 describes a mixture of antegrade and retrograde blood flow in the affected artery.
- Grade 3 (permanent or advanced subclavian steal syndrome): Grade 3 describes permanent retrograde blood flow in the affected artery.
People with subclavian steal syndrome often do not experience any symptoms. If symptoms do develop, they will vary according to the arteries it affects.
The sections below will outline some possible symptoms of subclavian steal syndrome.
Subclavian steal syndrome of the vertebral artery may cause neurological symptoms, particularly following certain head movements or upper body exercise.
Such symptoms occur because the brain and spinal cord are not receiving enough blood to function properly.
A 2020 article lists the following common neurological symptoms of subclavian steal syndrome:
Arm pain or discomfort
If subclavian steal syndrome affects an artery that carries blood to an arm, a person may experience symptoms in the affected arm, particularly following exercise. These symptoms occur because the arm is not receiving enough blood.
Some symptoms a person may experience in their arm include:
- abnormal tingling or prickling sensations
The body needs oxygenated blood to function properly. The role of arteries is to deliver oxygenated blood to different parts of the body.
A person has two subclavian arteries. Each artery sends blood to a different side of the body. The subclavian arteries send blood to the following areas:
- the chest
- the shoulders
- the arm
- the neck
- the head
The subclavian artery branches off into smaller arteries. These are the vertebral artery, which carries blood toward the neck and head, and arteries that carry blood toward the arms.
Subclavian steal syndrome occurs when the heart has difficulty pumping oxygenated blood through the subclavian artery. This can cause some degree of retrograde blood flow within the subclavian artery and the arteries that branch off from it.
As a result, people may experience symptoms of reduced blood flow to the neck and head or the arm.
An older study from 2010 suggests that people with a narrowed subclavian artery have an increased risk of mortality compared with the general population.
Because people with subclavian steal syndrome often do not experience symptoms, people at increased risk of the condition may benefit from regular health monitoring.
A study from 2014 notes that people with mild symptoms of subclavian steal syndrome may find that their condition improves without medical intervention.
However, those who experience more severe symptoms will require treatment. The type of treatment a person receives will depend on the cause of the condition.
The following sections outline some potential treatment options for subclavian steal syndrome.
People with atherosclerosis and other cardiovascular conditions can make certain lifestyle changes to help manage their condition.
These changes may include:
- quitting smoking
- following a healthful diet
- getting regular physical activity
- maintaining a moderate weight
- managing stress
Sometimes, lifestyle changes alone are not enough to address the underlying cause of subclavian steal syndrome. This is because in most cases, the cause is atherosclerosis.
People who have atherosclerosis may require medications called statins to control their blood cholesterol levels and prevent the formation of arterial plaques.
In some cases, they may also require additional medications to control inflammation or blood pressure or prevent the formation of blood clots.
Some people may require surgery to remove a blockage or address other causes of narrowing within the subclavian artery.
Atherosclerosis is the most common risk factor for subclavian steal syndrome. Atherosclerosis is a condition in which a person’s arteries become blocked or narrowed due to the buildup of fatty deposits called plaques.
The buildup of plaques makes it difficult for the heart to pump oxygenated blood through the subclavian artery. This can make a person more at risk of subclavian steal syndrome.
Risk factors for atherosclerosis include:
- having high cholesterol
- having high blood pressure
- having diabetes
- having a family history of the condition
- being older
Other possible risk factors for subclavian steal syndrome include:
- large artery vasculitis, which is the medical term for inflammation of the large arteries
- thoracic outlet syndrome, which is a group of conditions that occur when the blood vessels or nerves between the collarbone and first rib become compressed
- narrowing of the blood vessels following the surgical treatment of certain heart conditions
- certain congenital heart irregularities
- Takayasu’s arteritis, which is an inflammatory condition that affects the large blood vessels
- having an extra rib, called the cervical rib, which can put pressure on the subclavian artery
- undergoing surgical repair of the aorta
When diagnosing subclavian steal syndrome, a doctor will begin by evaluating the person’s symptoms. If these symptoms suggest subclavian steal syndrome, the doctor will recommend further testing.
The first line of testing is usually a duplex ultrasound. This is a noninvasive scan that measures blood flow in the body.
Sometimes, however, duplex ultrasounds are not precise enough to give a doctor all the information they need to confirm a diagnosis of subclavian steal syndrome.
In such cases, the doctor may recommend a magnetic resonance angiography (MRA). An MRA uses an MRI scanner to visualize blood flow in a person’s body.
The outlook for a person with subclavian steal syndrome depends on the underlying cause and whether or not it is possible to treat or manage that cause.
Some people find that their subclavian steal syndrome improves without medical intervention. However, a person who experiences a severe form of the condition will require treatment for the cause.
In all cases, it is helpful for someone with suspected subclavian steal syndrome to undergo a health check and regular monitoring. People at increased risk of developing it should also take such precautions. Some causes of subclavian steal syndrome can lead to serious and even life threatening complications without treatment.
Subclavian steal syndrome is a condition that affects blood flow within the subclavian artery and its adjoining arteries. The adjoining arteries supply blood to the neck and head or the arm. As a result, people with subclavian steal syndrome may experience symptoms in these areas.
Subclavian steal syndrome develops due to a blockage in or narrowing of a subclavian artery. The most common cause is atherosclerosis. Other risk factors include large artery vasculitis and congenital heart irregularities.
Without treatment, some causes of subclavian steal syndrome can lead to serious complications. Therefore, a person should see a doctor if they experience any symptoms of subclavian steal syndrome.
Since the condition is often symptomless, however, people at increased risk of developing it should undergo regular health monitoring.