SVC obstruction is a narrowing or blockage of the superior vena cava -- the second largest vein in the human body. The superior vena cava moves blood from the upper half of the body to the heart.

Superior vena cava (SVC) obstruction is a relatively rare condition. Symptoms occur when something blocks the blood flowing back to the heart.

Most often it is caused by cancer or a tumor in the mediastinum (the area of the chest under the breastbone and between the lungs). The types of cancer that can lead to this condition include lymphoma, cancer of the lung that spreads, breast cancer, testicular cancer, thyroid cancer, and thymic tumors.

Superior vena cava obstruction can also be caused by noncancerous conditions that cause chronic fibrosis (scarring). These conditions include lung infections (such as tuberculosis), histoplasmosis infection, and thrombophlebitis.

Other causes of superior vena cava obstruction include blood clots in the superior vena cava, aortic aneurysm, constrictive pericarditis, and goiter.

• Decreased alertness
• Dizziness
• Fainting
• HeadacheVision changes
• Neck swelling, facial swelling, or arm swelling
• Reddish face or cheeks
• Reddish palms
• Reddish mucous membranes (inside the nose, mouth, and so on)
• Redness changing to blueness later
• Sensation of head or ear "fullness"
• Swelling around the eye socket (periorbital)

Note: Symptoms may begin suddenly or gradually, and may worsen when bending over or lying down.

An examination may show enlarged veins of the face, neck, and upper chest. Blood pressure is often high in the arms and low in the legs.

A bronchoscopy may be performed if lung cancer is suspected.

Obstruction of the SVC may show on:

• Chest x-ray
• CT scan of the chest or MRI of chest
• Coronary angiography
• Doppler ultrasound
• Radionuclide ventriculography

This disease may also alter the results of the following tests:

• Liver scan
• Abdominal MRI

The goal of treatment is to relieve the obstruction.

Diuretics or steroids may be used to relieve swelling.

The cause must be identified and treated. This may include radiation, chemotherapy, surgical removal of tumors, or other treatment. Surgery to bypass the obstruction is rarely performed. Placement of a stent to open up the SVC is available at some medical centers.

The outcome varies depending on the cause and the extent of obstruction.

The throat could swell and block the airways.

Call your health care provider if you have a lung tumor and develop symptoms of SVC obstruction. Complications are serious and can sometimes be fatal.

Prompt treatment of other medical disorders may reduce the risk of developing SVC obstruction.

Rice TW, Rodriguez MR, Light RW. The superior vena cava syndrome: clinical characteristics and evolving etiology. Medicine (Baltimore). 2006;85;1:37-42.

Wilson LD, Detterbeck FC, Yahalom J. Superior vena cava syndrome with malignant causes. N Engl J Med. 2007;356;18:1862-1869.