Superior vena cava syndrome (SVCS)

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was reviewed on February 1, 2022.

Superior vena cava syndrome (SVCS) consists of a group of symptoms caused by a blockage or narrowing of the superior vena cava, a major vein that funnels blood from your head and upper body directly to your heart. Cancer can produce a blockage if a tumor presses on the vein. This rare syndrome can be potentially life-threatening in severe cases, and milder cases may show few, if any, symptoms.

SVCS and cancer

Cancers, including both small cell and non-small cell lung cancer, account for the majority of SVCS cases.

Others responsible for SVCS include lymphoma, breast and testicular cancers, thymus and other mediastinal cancers, and those that have spread (or metastasized) from elsewhere in your body to the vicinity of the superior vena cava, called the mediastinum. The mediastinum is the space in the chest between the lungs; it contains the heart, thymus gland, lymph nodes, esophagus and trachea (or windpipe).

SVCS typically results when a tumor or other tissue presses on the superior vena cava, restricting blood flow. A tumor may also grow into, or infiltrate, the superior vena cava, hindering blood flow and causing SVCS.

However, a growing number of cases result from blood clots and the narrowing of the superior vena cava associated with the increased use of pacemaker wires, implantable cardioverter-defibrillators, semipermanent catheters used for hemodialysis in kidney disease and injection of chemotherapy for cancer treatment.

Other noncancer causes for SVCS are:

  • Aortic aneurysms
  • Goiters (enlarged thyroid)
  • Tuberculosis and other lung infections
  • Histoplasmosis (a fungal infection that usually affects the lungs but can spread to other organs)
  • Radiation therapy
  • Constrictive pericarditis (when the heart’s sack-like covering tightens)
  • Vein inflammation (thrombophlebitis)

SVCS symptoms

The effects of SVCS depend upon where the obstruction occurs, the degree of obstruction, and how quickly it occurs. A slow-growing obstruction may not produce symptoms, and your body may attempt to counter the problem by shifting venous blood flow to other veins. The location of the obstruction determines which veins get used. One of these may be the inferior vena cava, which carries blood up from your legs and your abdomen to your heart.

Severe blockage creates problems for the parts of your body drained by the veins that feed into the superior vena cava. Symptoms may include:

  • Enlarged veins in your head and neck
  • Flushed face, which may be bluish-red in color
  • Headache
  • Dizziness or change in consciousness
  • Severe chest pain (angina)
  • Shortness of breath, especially when lying down
  • Coughing
  • Swelling of both arms
  • Swelling of breasts
  • Trouble swallowing

Diagnosing SVCS

Venography, which is radiographic imaging of your veins after you’ve been injected with a contrast medium, is considered the gold standard for identifying and assessing a blockage. Other imaging techniques, such as ultrasound of the veins of your upper body, plus magnetic resonance imaging (MRI) and computed tomography (CT) scans of your chest, can help determine whether you have SVCS and the location and size of the blockage. Imaging can also tell whether the blockage is generated by a clot (thrombus) in the superior vena cava or a tumor or noncancerous tissue pressing on it.

A simple maneuver called Pemberton’s sign can indicate if you have SVCS. It refers to the phenomenon of your face turning red and facial and neck veins swelling when you hold your arms straight up. This position compresses major veins and, if you have SVCS, it can quickly cause blood to build up in your head, resulting in a flushed appearance and vein engorgement. It was once used to diagnose large goiters in the chest, a cause of SVCS.

Treating SVCS

When caused by cancer, a sample (or biopsy) of the tumor may be taken to better understand the type of cancer, rate of growth, and how best to treat it. If the condition isn’t life-threatening and the symptoms aren’t rapidly progressing, then chemotherapy, radiation or a combination may be tried first. It can take weeks to shrink a tumor, so symptoms may persist for some time.

To temporarily relieve swelling, steroids and diuretics may be prescribed.

Doctors seldom opt to perform open surgery to create a bypass around the blockage. Instead, a stent may be placed.

Stents, which are mesh coils used to prop open blood vessels, may be surgically inserted to provide faster relief. Stenting may be indicated if you have severe symptoms, can’t tolerate radiation or chemotherapy, or if chemotherapy hasn’t reduced symptoms.

Before a stent is placed, the superior vena cava may be dilated using angioplasty. Angioplasty is a procedure used to unblock a blood vessel.

During an angioplasty, your surgeon inserts a thin catheter into a vein in your arm or groin and injects contrast dye. With an X-ray display for guidance, the catheter is threaded through your blood vessels until it reaches the blockage site. There, a small balloon on the end of the catheter is inflated to stretch open the blocked area and increase blood blow. Your surgeon then places a stent in the dilated area via the catheter.

SVCS may recur in some cases when stents later become blocked by clots, covered with tissue or otherwise compromised. In these cases, a new stent may be placed to restore adequate blood flow.

If a clot caused SVCS, a stent may be placed inside the superior vena cava. You may be given medicine to dissolve the clot and prevent new ones from forming.

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