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Superior Vena Cava Syndrome


This section has been reviewed and approved by the PLWC Editorial Board, 02/05

Superior vena cava syndrome (SVCS) is a collection of symptoms caused by the partial blockage or compression of the superior vena cava, the major vein that carries blood from the head, neck, upper chest, and arms to the heart. Nearly 95% of SVCS cases are caused by cancer.

Causes

The superior vena cava, which drains into the right atrium of the heart, can become compressed when a tumor growing inside the chest presses on the vein. The most likely cancers to cause SVCS are lung cancer (especially small cell lung cancer), squamous cell lung cancer, adenocarcinoma of the lung, non-Hodgkin lymphoma, large cell lung cancer, and other cancers that spread to the chest. In some cases, a tumor originally outside the superior vena cava may actually grow into, or invade, the vein causing a blockage. Because the superior vena cava lies close to a number of lymph nodes, any cancer that spreads to these lymph nodes, causing them to enlarge, can also cause SVCS. Enlarged lymph nodes compress the vein, which slows the blood flow and may ultimately result in complete blockage. A less common cause of SVCS is a thrombosis (blood clot) in the vein caused by an intravenous catheter or a pacemaker wire.

Symptoms

Symptoms usually develop slowly and include difficulty breathing or shortness of breath, coughing, and swelling of the face, neck, upper body, and arms. Rarely, patients may experience hoarseness, chest pain, difficulty swallowing, and coughing up blood.

Severe symptoms that are rarely seen include swelling of the veins in the chest and neck, fluid collection in the arms and face, and accelerated breathing. In severe cases, the skin may turn blue due to cyanosis (lack of oxygen). Also, in rare instances, the patient may experience paralysis of the vocal cords, and/or Horner's syndrome, characterized by a constricted pupil, sagging eyelid, and the absence of sweat on only one side of the face. SVCS can progress quickly to completely block the trachea (airway). When this occurs, a ventilator may be needed to help the patient breath until the obstruction can be treated. More commonly, if the blockage develops slowly, other veins may enlarge to carry extra blood and symptoms may be milder.

Diagnosis and treatment

Indications of SVCS can be seen with a chest x-ray and other imaging techniques, such as chest computerized tomography (CT) scan or magnetic resonance imaging (MRI). However, these tests are not diagnostic. If symptoms are mild, the trachea is not blocked, and there is good blood flow through other veins in the chest, treatment may not begin until a clear diagnosis is made, or treatment may not be necessary at all. In most cases, SVCS is managed by treating the underlying cancer with chemotherapy or radiation treatment directed at the mass causing the blockage. Other short-term treatments, aimed at reducing symptoms, include raising the patientís head, giving corticosteriods to reduce swelling, or using diuretics to eliminate excess fluid from the body. Less often, SVCS may be treated with thrombolysis (treatment to break up a blot clot in the vein), stent placement (a tube-like device inserted into the blocked area of the vein to allow blood to pass through), or surgery (to bypass a blockage caused by cancer).

Patient considerations

Because SVCS can cause serious breathing difficulties, it is considered an emergency. Patients and their families should learn about potential symptoms of SVCS and immediately report any symptoms to their doctor. Even though SVCS is serious and its symptoms can be frightening, it is successfully treated in most people.

SVCS in children

SVCS in children can be life threatening. Because a child's trachea is smaller and softer than an adult's, it can quickly swell or be squeezed shut causing breathing problems. Common SVCS symptoms in children are similar to those in adults and may include coughing, hoarseness, difficulty breathing, and chest pain. Fortunately, SVCS is rare in children, occurring in about 12% of children with cancer in the chest.

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