Venous Thoracic Outlet Syndrome

Venous thoracic outlet syndrome (VTOS) is a compressed subclavian vein. Your subclavian vein carries blood from your arm to your heart. If you have VTOS, you may have arm swelling, discoloration or heaviness. Treatment usually includes medications to dissolve blood clots. If needed, you may also have surgery.


Compression of veins and arteries between the collar bone and first rib causing venous thoracic outlet syndrome.
In venous thoracic outlet syndrome (VTOS), veins and arteries are compressed between the collar bone and first rib.

What is venous thoracic outlet syndrome?

Venous thoracic outlet syndrome (VTOS) is a condition that affects your subclavian vein. Veins take blood from your tissues back to your heart and lungs to collect oxygen. The subclavian vein is in your arm behind your collarbone (clavicle). The space where this vein runs is the thoracic outlet.

In VTOS, you have a squeezed (compressed) vein in the thoracic outlet. People with VTOS often have arm soreness, swelling or discoloration. Another name for VTOS is Paget-Schroetter syndrome (PSS).


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Who might get venous thoracic outlet syndrome?

Women ages 20 to 50 are more likely to get any type of thoracic outlet syndrome. You are also more likely to develop VTOS if you play sports or have a job that requires repetitive motion in your arm and shoulder.

What are the complications of venous thoracic outlet syndrome?

VTOS can be dangerous if you don’t get treatment. The compression from VTOS can cause blood clots to form in the subclavian vein. The clots can block blood flow in your arm or hand or to your lungs. A blood clot that moves to your lungs is a pulmonary embolism.

If you have symptoms of thoracic outlet syndrome, see a doctor for a diagnosis. If you have severe symptoms that could point to possible pulmonary embolism, seek emergency care. A pulmonary embolism causes chest pain, cough and shortness of breath.


How common is venous thoracic outlet syndrome?

Experts don’t know exactly how many people have thoracic outlet syndrome. All types of TOS are rare, and VTOS is one of the least common types of TOS. About 2 in 50 people with TOS have it.

Symptoms and Causes

What causes venous thoracic outlet syndrome?

Between your clavicle and first rib, a vein called the subclavian vein carries blood from your arm back to your heart. Most people have plenty of space for the subclavian vein to run from their arm to their heart without being abnormally compressed. But some people have a naturally narrow passageway for the subclavian vein.

If you have a narrow passageway, overusing your arm and shoulder can squeeze (compress) or aggravate the subclavian vein. This compression can block blood flow and lead to clots.

Other causes of venous thoracic outlet syndrome can include:

  • Carrying extra weight (obesity), which puts extra pressure on your joints.
  • Physical trauma, such as injuries due to a car accident or fall.
  • Posture (how you sit and stand).
  • Pregnancy.
  • Repetitive movements, such as throwing a ball, lifting boxes overhead or swinging a baseball bat.


What are the symptoms of venous thoracic outlet syndrome?

Most people with VTOS have symptoms that affect one arm and hand. You may have:

  • Aching.
  • Blue or purple discoloration.
  • Heaviness.
  • Swelling.
  • Visible veins in one shoulder, arm or on one side of your chest.

Diagnosis and Tests

How is venous thoracic outlet syndrome diagnosed?

If you have VTOS symptoms, your provider will visually examine your shoulder, neck and arm. Your provider may ask you to move your arms in specific ways to check your range of motion.

Your provider will also ask you about symptoms and take your blood pressure. If your provider suspects VTOS, you may have more tests to examine your thoracic outlet.

What tests might I have to diagnose venous thoracic outlet syndrome?

Venous thoracic outlet diagnosis may involve imaging tests. To view blood flow in your veins and internal structures, you may have:

  • CT scan: Using multiple X-rays to create detailed images.
  • MRI: Using radio waves and magnets to get a detailed picture.
  • Ultrasound: Using sound waves to look inside your body, including viewing blood flow.
  • Venogram: Placing a small, hollow tube (catheter) and contrast dye in your veins before taking an X-ray.
  • X-ray: Using targeted, safe doses of radiation to get images.

Management and Treatment

How is venous thoracic outlet syndrome treated?

VTOS treatment can include nonsurgical and surgical options. Typically, your provider prescribes medications to dissolve blood clots. You may take anticoagulants such as warfarin (Coumadin®) or direct oral anticoagulants (Xarelto® or Eliquis®).

After the clot breaks up, you may need surgery to prevent blood clots from occurring again. During surgery, your provider may:

  • Remove extra tissue or ligaments around the subclavian vein.
  • Redirect blood flow to avoid damaged veins and restore circulation.


How can I reduce my risk of venous thoracic outlet syndrome?

There’s no guaranteed way to avoid VTOS. But you can lower your risk of compression injuries by:

  • Achieving and maintaining a healthy weight for your age, sex and body type.
  • Avoiding carrying heavy bags on one shoulder.
  • Limiting repetitive overhead movements.
  • Strengthening your shoulders with resistance training or weight lifting.
  • Stretching your neck, shoulders and chest daily.

Outlook / Prognosis

What is the outlook for venous TOS?

Without treatment, venous thoracic outlet syndrome can cause complications such as blood clots. Thankfully, early treatment helps.

Research shows that getting treatment within the first 14 days of symptoms significantly increases your chances of a successful outcome. If you have any signs of VTOS, see a healthcare provider right away.

Living With

What else should I ask my doctor?

You may also want to ask your healthcare provider:

  • What is the most likely cause of venous TOS symptoms?
  • What tests do I need for diagnosis?
  • What are the treatment options?
  • Will nonsurgical treatments improve my symptoms?
  • What lifestyle changes can I make to improve symptoms?

A note from Cleveland Clinic

Venous thoracic outlet syndrome affects the subclavian vein. A compressed subclavian vein can lead to arm swelling, discoloration and soreness. You are more likely to get VTOS if you have a naturally narrow passageway for the subclavian vein. Frequent, repetitive shoulder and arm movements also increase your risk of VTOS. If you have VTOS, your provider may prescribe medications to dissolve blood clots. You may also need surgery to widen the area around your subclavian vein.

Medically Reviewed

Last reviewed on 01/31/2022.

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