Superior Vena Cava
Syndrome
Overview
Superior vena cava syndrome (SVCS) is
a collection of symptoms caused by the partial blockage of the vein
that carries blood from the head, neck, chest, and arms to the
heart. Symptoms that may indicate this syndrome include difficulty
breathing, coughing, and swelling of the face, neck, upper body, and
arms. In rare occasions, patients may complain of hoarseness, chest
pain, difficulty swallowing, and coughing up blood. Physical signs
of SVCS include swelling of neck or chest veins, collection of fluid
in the face or arms, and rapid breathing. Rarely, cyanosis (lack of
oxygen in the blood causing a bluish color to the skin), Horner's
syndrome (constricted pupil, drooping eyelid, and no sweating on one
side of the face), and a paralyzed vocal cord may also be present.
SVCS is usually a sign of locally
advanced lung cancer. Survival depends on the status of the
patient's disease. Most non-Hodgkin's lymphoma patients with SVCS
respond to appropriate chemotherapy or to combined types of
treatment.
Causes
Nearly 95% of superior vena cava
syndrome cases are attributed to cancer, with the most common cause
being small cell lung cancer, followed by squamous cell lung cancer,
adenocarcinoma of the lung, non-Hodgkin's lymphoma, and large cell
lung cancer. Another cause in cancer patients is a blood clot
associated with intravenous catheters or pacemaker wires. A rare
cause of superior vena cava syndrome is an infection of the
mediastinum (in the chest), that causes thickening and hardness of
the mediastinal tissues. Other rare causes of superior vena cava
syndrome include metastatic germ cell tumors, metastatic breast
cancer, colon cancer, Kaposi's sarcoma, cancer of the esophagus,
fibrous mesothelioma (cancer of the epithelium), Bechet's syndrome
(a disease of the immune system), thymus tumor, thyroid tumor,
Hodgkin's lymphoma, and sarcoidosis (disease of the lymph nodes that
acts like tuberculosis).
The major veins connected to the
right atrium (a chamber of the heart) are the superior vena cava and
the inferior vena cava. The superior vena cava returns blood from
the upper body to the heart, and the inferior vena cava returns the
blood from the lower part of the body. Two valves in the right
atrium connect these two major veins and control the flow of the
blood into the heart. The superior vena cava is thin-walled, and the
blood is under low pressure. It lies near lymph nodes in the chest.
Therefore, when the lymph nodes or the aorta of the heart get
bigger, the superior vena cava is squeezed, blood flow slows, and
complete blockage may occur.
The speed of the blockage and its
location determine the seriousness of the syndrome. The more rapidly
the obstruction occurs, the more severe the symptoms, since the
other veins do not have time to widen to adjust to the increased
blood flow. If the blockage occurs above where the superior vena
cava and inferior vena cava meet, the syndrome is less obvious,
since the veins can swell more easily and handle the increased blood
flow. If the blockage occurs below this point, more symptoms are
seen, since the blood must be returned to the heart by the veins in
the upper abdomen and the inferior vena cava, which requires higher
pressure.
Sometimes, the other veins can take
over for the superior vena cava if it is obstructed, but this takes
time.
Diagnosis
Once superior vena cava syndrome is
recognized, prompt attention is important. A definite diagnosis
should be made before starting therapy because most patients have
symptoms for longer than 1 week before getting medical help; cancer
patients diagnosed with superior vena cava syndrome do not die of
the syndrome itself but rather from the cancer; and 3% to 5% of
patients diagnosed with superior vena cava syndrome do not have
cancer.
As long as the trachea is not
blocked, superior vena cava syndrome is not usually a
life-threatening emergency; therefore, a definite diagnosis should
be made before treatment is begun.
A chest x-ray, computed tomography
(CT) scanning of the chest, imaging of the veins, magnetic resonance
imaging, and ultrasound may all be used in determining the site and
type of blockage.
If lung cancer is suspected, a sputum
specimen should be collected. If the sputum specimen is negative, a
biopsy may be taken. The results of the biopsy will help the doctor
decide on the best treatment.
Treatment
Treatment of superior vena cava
syndrome depends on the cause of the obstruction, the seriousness of
the symptoms, the prognosis of the patient, and the patient's
preferences. Radiation therapy and chemotherapy should not be
started until the cause of the blockage is determined. The
treatments discussed in this summary will focus on superior vena
cava blockage caused by cancer. Since the treatment of the blockage
may depend on the type of cancer, this diagnosis should be made
before treatment is started. Unless the airway is blocked or the
brain is swelling, waiting to start treatment usually presents no
problem. The following treatments can be used for superior vena cava
syndrome.
Medical Management
A patient with good blood flow
through other veins and few symptoms may not need treatment. If the
blockage is above the area where the superior and inferior vena cava
veins join, and other veins are able to take over for the superior
vena cava, the symptoms may stabilize and the patient may be
comfortable enough to forego more therapy. Short-term relief for a
patient who has symptoms, but who does not want aggressive
treatment, may include raising the head, using corticosteroids, and
increasing elimination of fluids using drugs such as diuretics.
Diuretics may help symptoms of swelling, but can cause problems such
as dehydration.
Radiation Therapy
If the blockage of the superior vena
cava is caused by a tumor that is not sensitive to chemotherapy,
radiation therapy may be given.
Chemotherapy
Chemotherapy is the treatment of
choice for sensitive tumors such as lymphoma or small cell lung
cancer. The presence of superior vena cava syndrome should not
change the treatment approach. The rapid start of chemotherapy can
result in complete and partial response rates of superior vena cava
syndrome of more than 80% in small cell lung cancer.
Thrombolysis (Breaking
Up Blood Clots)
Superior vena cava syndrome may come
about when a thrombus (blood clot) forms in a partially blocked
vein. Patients who have blood clots may need treatment to dissolve
or remove the blood clot.
Stent Placement
A stent may be used to open up the
blocked vein. A stent is a tube like device that is inserted into
the blocked area of a vein to allow blood to pass through. This may
help about 90% or more of patients. Sometimes, patients may also
receive an anticoagulant to keep more blood clots from forming.
Surgery
Surgical bypass of a blocked superior
vena cava is used more often for patients without cancer, although
it is used sometimes for cancer patients with blockages caused by
cancer.
Social Considerations
Patients and family members are often
frightened and anxious because of the symptoms of superior vena cava
syndrome, particularly swelling, trouble swallowing, coughing, and
hoarseness. Patients and their families should receive information
about the cause of symptoms and their short-term treatment. When
aggressive treatment is refused because of terminal cancer, patients
and family members can be taught to treat symptoms.
Because most adult patients who
develop superior vena cava syndrome have lung cancer, the type of
treatment and care prescribed should take into account the patient's
prognosis and other symptoms caused by the cancer.
Superior Vena Cava
Syndrome Occurring in Children
Superior vena cava syndrome refers to
blockage of the superior vena cava, while the squeezing of the
trachea (windpipe) is called superior mediastinal syndrome. Since
superior mediastinal syndrome and the resulting breathing problems
frequently occur in children with superior vena cava syndrome, the
two syndromes are considered to be the same in children. In adults,
the windpipe is fairly rigid, but in children it is softer and more
likely to be squeezed shut. Also, the diameter of a child's windpipe
is smaller, so any amount of swelling can cause breathing problems.
Therefore, superior vena cava syndrome is different from the
syndrome in adults and is a serious medical emergency.
The most common symptoms in children
are similar to those in adults and include coughing, hoarseness,
difficulty breathing, and chest pain. Other less common but more
serious symptoms include anxiety, confusion, tiredness, headache,
vision problems, a sense of fullness in the ears, and, especially,
fainting.
Superior vena cava syndrome is rare
in children and appears in 12% of children with cancer in the chest.
The cause, diagnosis, and treatment of superior vena cava syndrome
in children is not the same as it is in adults. While the most
common cause of superior vena cava syndrome in adults is lung
cancer, in children it is non-Hodgkin's lymphoma. As with adults, a
frequent noncancerous cause is a blood clot associated with an
intravenous catheter.
A physical examination, chest x-ray,
and medical history are usually all that are needed to determine the
diagnosis of superior vena cava syndrome. If lymphoma or another
cancer is suspected, a biopsy is helpful for the diagnosis, but may
be too dangerous for the child. Children with superior vena cava
syndrome do not tolerate general anesthesia well because of its
effect on the heart and lungs.
When cancer is the cause of superior
vena cava syndrome, the situation may be a medical emergency, with
no time to diagnose the cancer with tissue. In most cases, the best
approach is to start treatment before a definite diagnosis is made.
Radiation therapy is usually used to treat the tumor. After
radiation therapy, breathing may become more difficult because of
the rapid swelling that narrows the windpipe. In these situations,
it may be necessary to give a drug that reduces swelling.
Along with radiation, chemotherapy
with steroids, cyclophosphamide, or both with other drugs may be
used. If the tumor does not respond, it may not be cancerous. If
necessary, surgery may be performed.
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