The superior vena cava is the vein that carries deoxygenated blood from the upper body to the heart.

Superior vena cava syndrome is often a secondary problem caused by a cancerous tumor or a blood clot that restricts blood flow through this particular vein.

It used to be considered a medical emergency. However, doctors no longer believe this to be the case.

Even so, those experiencing symptoms of superior vena cava syndrome should be evaluated promptly by a doctor.

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The superior vena cava is a large vein of the heart.

The superior vena cava is the larger of the two veins that transport deoxygenated blood back to the heart.

The superior vena cava carries used blood from the head and upper body to the right atrium (upper chamber) of the heart. This vein is in the middle of the chest and is surrounded by lymph nodes.

Superior vena cava syndrome is the name given to the symptoms that occur when the blood flow through the superior vena cava is blocked or compressed.

These symptoms include breathing problems, lightheadedness, and swelling in the upper body.

Superior vena cava syndrome most often occurs as a complication of another medical issue, such a tumor or a swollen lymph node obstructing the flow of blood through the vein.

Common causes of superior vena cava syndrome include:

Less common causes of superior vena cava syndrome include:

  • metastatic breast cancer
  • colon cancer
  • esophageal cancer
  • thyroid cancer
  • Hodgkin lymphoma
  • blood clots from an intravenous catheter or pacemaker
  • severe chest infections, such as tuberculosis
  • some immune system diseases, such as Behcet’s disease
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Symptoms of superior vena cava syndrome may include hoarseness, chest pain, and coughing.

If the obstruction causing superior vena cava syndrome is not causing a total blockage, a person may not experience any symptoms.

More often, a person with a partial blockage will experience mild symptoms that they may overlook.

If the blockage is complete or worsens quickly, a person is likely to experience more extreme symptoms.

Symptoms may include a combination of the following:

  • coughing
  • difficulty breathing or swallowing
  • hoarseness
  • chest pain
  • coughing up blood
  • swollen veins in the neck or chest
  • arm swelling
  • facial swelling
  • stridor or wheezing
  • nausea
  • lightheadedness
  • red skin on the chest or neck

Superior vena cava syndrome in children

Although rare, superior vena cava syndrome in children is always a medical emergency.

A child’s windpipe is smaller and less rigid than an adult’s, making it more prone to swelling quickly and causing breathing problems. Symptoms are often similar to those in adults and tend to be due to lymphoma (cancer of the lymphatic system).

Symptoms in pregnancy

Pregnant women in their late second and third trimester may experience a condition similar to superior vena cava syndrome. Symptoms occur when the inferior vena cava (the smaller of the two veins that transport deoxygenated blood back to the heart) gets compressed by pressure from the fetus and the enlarged uterus.

A pregnant woman may experience lightheadedness and low blood pressure when lying directly on her back. Lying on the left side often resolves these symptoms.

If a doctor suspects a person has superior vena cava syndrome, they will first do a physical exam. The exam may show enlarged veins in the upper body.

If the physical exam suggests superior vena cava syndrome, a doctor will likely order several additional tests, including:

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Additional tests, such as a chest X-ray, may be ordered by a doctor.
  • a chest X-ray to check for tumors in the lungs or an enlargement in the chest
  • a CT scan to show blockages
  • venography, which is an X-ray of the veins after an injection of a special dye that makes the veins visible
  • an ultrasound to look for blood clots in the upper extremities

If a tumor is found to be responsible for the blockage, a doctor may order a biopsy to determine what type of tumor is causing the problem. Knowing whether the tumor is cancerous or benign is essential for receiving proper treatment.

In most cases of superior vena cava syndrome, treatment aims to reduce symptoms and shrink any tumor causing the obstruction. In mild cases, watchful waiting may be the only treatment recommended.

Many people with superior vena cava syndrome see vast improvements in their symptoms by keeping their head elevated and using supplemental oxygen. Some doctors may also try to reduce swelling with prescribed steroids.

Most treatment of superior vena cava syndrome focuses on addressing the underlying cause of the syndrome.

Since the majority of cases occur due to cancer, appropriate treatment is key. Treatment will depend on the type of cancer involved and may include a combination of chemotherapy and radiation.

In cases where superior vena cava syndrome is caused by a blood clot, blood thinners may be prescribed. A stent may also be used to open up the vein. In rare cases, bypass surgery may be performed.


In most cases, symptoms of superior vena cava syndrome are greatly improved within 1 month of treatment. However, because cancer causes the majority of cases, the general outlook depends heavily on the type and stage of cancer present.