Superior vena cava syndrome (SVCS) is a group of symptoms caused when the main vein (superior vena cava) that carries blood from the upper body (e.g. head, neck, chest and arms) to the heart, becomes partially blocked. The superior vena cava is connected to the right side of the heart (atrium) and is located near lymph nodes in the chest. The superior vena cava is a thin-walled blood vessel. When it becomes compressed, blood flow to the heart slows and the veins of the upper body become congested with blood. The superior vena cava can become completely blocked by a large tumour or lymph nodes.
Causes
Most cases of superior vena cava syndrome are caused by primary tumours in the chest (mediastinum):
- advanced lung cancer
- small cell lung cancer – most common cause
- non-small cell lung cancer
- non-Hodgkin's lymphoma
SVCS can also be caused by other cancers:
- Hodgkin's disease
- metastatic breast cancer
- metastatic colon cancer
- metastatic germ cell tumours
- Kaposi's sarcoma
- cancer of the esophagus
- thymus tumour
- thyroid cancer
The rate and location at which the superior vena cava becomes blocked, determines the seriousness of SVCS.
SVCS can also be caused by non-cancerous conditions such as a blood clot from a central venous catheter, pacemaker wires or an infection of the mediastinum.
Symptoms
The symptoms of SVCS usually develop gradually. The more rapidly the blockage (obstruction) occurs, the more severe the symptoms. Sometimes other veins in the upper body are able to widen to adjust to the increased blood flow and symptoms will be less severe. The most common symptoms are:
- difficulty or rapid breathing
- bending over or lying flat can make breathing problems worse
- coughing
- swelling of the face, neck, upper body, and arms
The less common symptoms of SVCS are:
- hoarseness
- chest pain
- trouble swallowing (dysphagia)
- coughing up blood (hemoptysis)
- bluish colour of the lips and skin (cyanosis) caused by low levels of oxygen in the blood
- constricted pupil, drooping eyelid and no sweating on one side of the face (Horner's syndrome)
- headache, anxiety, dizziness and confusion may indicate swelling of the brain
Diagnosis
Most people have symptoms for more than one week before they see a doctor. Tests that help diagnose SVCS include:
- chest x-ray
- computed tomography (CT) scan of the chest
- magnetic resonance imaging (MRI)
- ultrasound
- a sputum specimen if lung cancer is suspected
- if the sputum specimen is negative, a biopsy may be done
- venogram – an x-ray using a contrast medium to visualize veins in the upper body
A definite diagnosis is made before treatment is started.
Treatment
- Treatment of SVCS depends on:
- the cause of the problem
- the type of cancer, if the problem has been caused by cancer
- the seriousness of the symptoms
- the person's prognosis
- the person's preferences
Treatment will not start until the cause of the blockage of the superior vena cava is found. A person with good blood flow through other veins, few symptoms or an open airway, may not need treatment right away. However, if the windpipe (trachea) becomes blocked, superior vena cava syndrome can become life-threatening and immediate treatment is necessary.
Supportive measures for SVCS include:
- raising the head of the bed
- oxygen therapy
- drugs (corticosteroids) to decrease swelling (edema)
- fluid pills (diuretics) to get rid of extra fluid
The following treatments may be used:
Radiation therapy
- used if the tumour is sensitive to radiation therapy
- number and length of radiation treatments depends on the type of cancer causing SVCS, tumour size, previous radiation therapy to the chest and how responsive SVCS is to radiation
Chemotherapy
- used if the tumour is sensitive to chemotherapy and a rapid response is required – small cell lung cancer, lymphoma
Stent
- a tube-like device (stent) is inserted into the blocked area of the vein to open up the vein and allow blood to pass through
- sometimes blood thinners (anticoagulants) are used to keep blood clots from forming
Surgery
- done more often in people without cancer
- a vein graft, usually taken from the leg, is used to bypass the blockage
- the graft is used to connect a larger vein in the upper chest to the right atrium, bypassing the superior vena cava
Relief of symptoms usually occurs within the first week or two of treatment, but can occur sooner depending on the treatment. Combinations of treatments may also be needed.