Superior Vena Cava (SVC) Syndrome

How SVC syndrome develops

The superior vena cava runs through the middle of the chest (mediastinum), surrounded by lymph nodes, the windpipe and the right lung. It has thin walls and low pressure, so it is easily compressed by tumors or enlarged lymph nodes, or blocked by a clot. When flow is obstructed, blood finds detour routes through smaller veins in the chest wall and back (collateral veins), which become visibly enlarged. If obstruction develops slowly, collaterals can partly compensate, so symptoms may be mild.

Causes

Cancer (most cases)

• Lung cancer, especially small cell lung cancer
• Non-Hodgkin lymphoma
• metastatic cancers (such as breast cancer) in chest lymph nodes
• thymoma and germ cell tumors

SVC syndrome is sometimes the first sign of an undiagnosed cancer.

Non-cancer causes

• Thrombosis related to central venous catheters, dialysis lines, ports and pacemaker or defibrillator leads; this is a growing share of cases. See catheter thrombosis.
• Fibrosing mediastinitis, scarring in the chest, sometimes after histoplasmosis or tuberculosis
• Radiation scarring
• Benign goiter or aortic aneurysm (rare)

Symptoms

• swelling of the face, neck and eyelids, often worst on waking
• swelling of the arms and hands
• visible, swollen veins on the neck, chest and upper abdomen
• a red or purple, flushed face
• shortness of breath, worse lying flat
• cough, hoarseness or difficulty swallowing
• headache, a feeling of pressure in the head, dizziness, especially bending forward
• chest pain

Raising both arms above the head may make the face flush and congested (Pemberton sign).

Diagnosis

1. Examination: swelling, dilated veins and breathing assessment.
2. CT scan of the chest with contrast: shows the blockage, its cause and collateral veins.
3. Ultrasound of arm and neck veins for clots.
4. Venography if stenting is planned.
5. Biopsy of a tumor or lymph node to determine the type of cancer, ideally before steroids or radiation, which can make diagnosis harder, unless symptoms are life-threatening.

Treatment

Immediate relief

• Raise the head of the bed and give oxygen as needed.
• Endovascular stenting: a radiologist places a metal stent in the vein through a catheter, often relieving symptoms within 24 to 72 hours. It is used for severe symptoms or when other treatments are slow to work.
• Steroids may reduce swelling in specific cases, such as lymphoma.

Treating the cause

• Chemotherapy for sensitive tumors such as small cell lung cancer and lymphoma, often relieving obstruction within 1 to 2 weeks.
• Radiation therapy for tumors less responsive to chemotherapy.
• Blood thinners for clots, sometimes with clot-dissolving treatment or removal or replacement of the catheter or device.
• Surgery (bypass) in rare benign cases.

Outlook

SVC syndrome itself is rarely immediately life-threatening when it develops slowly, but the outlook depends mainly on the underlying cause. Symptoms usually improve quickly with stenting or treatment of the tumor. When cancer is the cause, it often indicates advanced disease, though lymphoma and small cell lung cancer can respond well to treatment.

Frequently asked questions

What is superior vena cava syndrome?

It is a condition in which the superior vena cava, the large vein draining blood from the head, neck and arms, is narrowed or blocked. Blood backs up, causing swelling of the face, neck and arms, swollen chest veins, breathlessness and headache.

What causes SVC syndrome?

Most cases are caused by cancers in the chest, especially lung cancer and lymphoma, pressing on or invading the vein. A growing number are caused by blood clots related to central lines, ports, dialysis catheters or pacemaker wires. Rarely, scarring or infection is the cause.

Is superior vena cava syndrome an emergency?

It needs prompt evaluation, usually the same day. It becomes an emergency if there is noisy or difficult breathing, throat swelling, confusion, severe headache or fainting. Stenting and treatment of the cause usually relieve symptoms quickly.

How is SVC syndrome treated?

Treatment includes placing a stent to reopen the vein, treating the underlying cancer with chemotherapy or radiation, and using blood thinners or removing a catheter when a clot is the cause. Raising the head and giving oxygen help in the meantime.