Compression or obstruction of the superior vena cava, a major vein in your body, can lead to superior vena cava syndrome, or SVCS. It’s treatable, but most cases are caused by cancer.

The superior vena cava is one of the primary veins within our bodies. It transports blood from our arms, chest, neck, and head to our hearts. In superior vena cava syndrome (SVCS), this vein has become obstructed or compressed to some degree. One of the main causes of SVCS is cancer.

SVCS usually results in a group of symptoms that develop slowly over time. If these symptoms are ignored, SVCS can cause serious breathing problems and become a medical emergency. If you experience any of the common symptoms of SVCS you should seek medical advice immediately.

The common symptoms of SVCS are:

There are some other symptoms of SVCS, but these occur more rarely. They are:

  • a hoarse throat
  • quicker respiration
  • chest pain
  • difficulty with swallowing
  • swollen veins in the chest and neck
  • coughing up blood
  • a blue tinge to the skin due to lack of oxygen
  • paralysis of the vocal chords
  • Horner’s syndrome, which includes a small pupil, drooping eyelid, and lack of perspiration on one side of your face
  • confusion, lightheadedness, and passing out (syncope)

Symptoms in children

SVCS can be life-threatening for children because their airways are smaller and softer than those of adults. The symptoms in children are the same as for adults. But due to the more serious nature of the condition for children, it’s even more important that you seek medical help for them as soon as any of these symptoms are displayed.

Symptoms during pregnancy

Those in the latter stages of their pregnancy may experience a condition similar to SVCS called inferior vena cava syndrome. This occurs when the smaller vein transporting blood to the heart from the lower body gets compressed by the growing uterus.

Pregnant people with inferior vena cava syndrome may experience lightheadedness and low blood pressure when they lie on their backs. Lying on the left side usually eases symptoms.

The majority of cases of SVCS are caused by cancer. It’s most common in people with lung cancer, non-Hodgkin’s lymphoma or any other cancer that has spread to the chest, including breast cancer.

Tumors in the chest may press on or grow into the superior vena cava. If the cancer spreads to the lymph nodes around the superior vena cava, they can enlarge and press on or cause a blockage in the vein.

SVCS can also be caused by a blood clot in the vein. They can be caused by a pacemaker wire or an intravenous catheter, which is a flexible tube put into a vein to remove or add fluids.

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Illustration by Antonio Jimenez

Your blood travels in two systems through your body:

  • the arterial system, which carries oxygen-rich blood
  • the venous system, which carries blood that doesn’t have oxygen back to the heart

The superior vena cava is a part of the venous system. It collects blood that drains from the head, neck, upper chest, and arms back toward the heart. The blood returns to the right part of the heart known as the atrium, where it will go to the lungs to receive oxygen.

If you have superior vena cava syndrome, blood doesn’t flow as well to the heart. This is a problem because it delays the heart’s ability to get oxygen to the blood. As a result, a person will have problems getting enough oxygen to their body.

The effects of SVCS depend on whether the underlying condition is treatable. Some causes can be corrected — such as removing or relocating a medical device, like a central line or implanted defibrillator. Others may depend on surgery and cancer treatments.

If your doctor suspects that you may have SVCS, there are a variety of tests that may be used to confirm this diagnosis. They may recommend any combination of:

Previously, doctors could only restore blood flow to the heart via open surgical treatments. However, there have been advancements, which means doctors can repair the affected area. Treatment for SVCS varies depending on its underlying cause:

  • If cancer is the reason, the main treatment for SVCS is to target the cancer that’s causing it with chemotherapy or radiotherapy.
  • If the SVCS is due to a pacemaker or cardiac device, doctors usually don’t recommend stenting. Instead, they may remove and replace the positioning of the device.
  • If the SVCS is caused by a blood clot, your doctor may recommend thrombolysis, a treatment to break up the clot within the vein, or that a stent be inserted to hold open the blocked vein. Surgery to bypass any blockages may also be an option.
  • To perform endovascular repair, your doctor will gain access to the venous system — this is usually through the femoral vein in your groin. They will then thread a special catheter upward to reach the area where the superior vena cava is blocked. If possible, they will place a stent to hold the vessel open and remove any blood clots present.
  • Your doctor may also prescribe corticosteroids to reduce swelling or diuretics to remove excess fluid from your body by increasing urination.

When blood doesn’t return effectively to the heart, your body tries to solve the problem by creating more veins. This is known as developing collateral circulation. They are like an alternate route from the superior vena cava to try to get blood back to the heart.

Even with collateral circulation, you can still experience symptoms, such as:

  • swelling, most worrisome in the brain and larynx (which affects breathing)
  • cough
  • nausea
  • problems swallowing
  • shortness of breath
  • upper arm swelling

If SVCS isn’t treated effectively, then ultimately it can lead to an inability to breathe, which can be fatal. SVCS is most commonly associated with cancers that occur in the chest area, but it has also been associated with syphilis and tuberculosis.

The outlook for SVCS depends upon the condition’s underlying cause and additional symptoms. If patients have symptoms of brain or throat swelling, the prognosis is poor and can result in sudden death.

Patients with lung cancer who experience SVCS have a life expectancy that doesn’t usually exceed 24 months. If your cancer doesn’t respond to radiation treatments to shrink the mass, the survival rates are usually less than one year.

These numbers can vary based on your unique condition and overall health. Talk with your doctor about your individual outlook.

Superior vena cava syndrome itself is very treatable, and symptoms are usually greatly improved within the first month of treatment.

However, because the majority of cases are caused by cancer, the overall outlook will depend on the type and stage of the cancer involved.