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 obstruction; Superior vena cava syndrome

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
• Thymus tumors

Superior vena cava obstruction can also be caused by noncancerous conditions that cause scarring. These conditions include:

• Histoplasmosis infection
• Inflammation of a vein ( thrombophlebitis)
• Lung infections (such as tuberculosis)

Other causes of superior vena cava obstruction include:

• Aortic aneurysm (widening of the artery that leaves the heart)
• Blood clots in the superior vena cava
• Constrictive pericarditis (tightening of the thin lining of the heart)
• Effects of radiation therapy for certain medical conditions
• Enlargement of the thyroid gland (goiter)

Catheters placed in the large veins of the upper arm and neck may cause blood clots in the superior vena cava.

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

Early signs include:

• Swelling around the eye
• Swelling of the face
• Swelling of the whites of the eyes

The swelling will most likely be worse in the early morning hours and go away by mid morning.

The most common symptoms are shortness of breath (dyspnea) and swelling of the face, neck, trunk, and arms.

Other possible symptoms include:

• Decreased alertness
• Dizziness
• Fainting
• Headache
• Reddish face or cheeks
• Reddish palms
• Reddish mucus membranes (inside the nose, mouth, and other places)
• Redness changing to blueness later
• Sensation of head or ear "fullness"
• Vision changes

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 (a lighted tube placed through the mouth into the windpipe and lungs) may be performed if lung cancer is suspected.

Blockage of the SVC may be visible on:

• Chest x-ray
• CT scan of the chest or MRI of chest
• Coronary angiography (a heart blood vessel study)
• Doppler ultrasound (sound wave test of the blood vessels)
• Radionuclide ventriculography (nuclear study of heart motion)

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

• Abdominal MRI or CT scan
• Liver scan

The goal of treatment is to relieve the blockage.

Diuretics (water pills) or steroids may be used to relieve swelling.

Other treatment options may include radiation or chemotherapy to shrink the tumor, or surgery to remove the 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 amount of blockage.

SVC syndrome caused by a tumor is a sign that the tumor has spread, and it indicates a poorer long-term outlook.

The throat could become blocked, which can block the airways.

Increased pressure may develop in the brain, leading to changed levels of consciousness, nausea, vomiting, or vision changes.

Call your health care provider if you 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.

Ugras-Rey S, Watson M. Selected oncologic emergencies. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier;2009:chap 121.