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.

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:

• Breast cancer
• Lymphoma
• Metastatic lung cancer (lung cancer that spreads)
• Testicular cancer
• Thyroid cancer
• Thymic tumors

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

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

Symptoms occur when something blocks the blood flowing back to the heart. They may begin suddenly or gradually, and may worsen when bending over or lying down.

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

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.

Other treatment options may include radiation, chemotherapy, or surgical removal of tumors. 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 become obstructed and block the airways.

Elevated pressure may develop in the brain, resulting in altered levels of consciousness, nausea, vomiting, or visual changes.

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;356:1862-1869.