Background
Superior vena cava syndrome (SVCS) is characterized by gradual, insidious compression/obstruction of the superior vena cava. Although the syndrome can be life threatening, its presentation is often associated with a gradual increase in symptomatology. For this reason, diagnosis is often delayed until significant compression of the superior vena cava has occurred.
Pathophysiology
Extrinsic compression of the superior vena cava is possible because it has a thin wall coupled with a low intravascular pressure. Because the superior vena cava is surrounded by rigid structures, it is relatively easy to compress. The low intravascular pressure also allows for the possibility of thrombus formation, such as catheter-induced thrombus.
The subsequent obstruction to flow causes an increased venous pressure, which results in interstitial edema and retrograde collateral flow.
Etiology
The most common etiology of superior vena cava syndrome is malignancy. [1]
Prior to modern antibiotics, infectious causes including syphilis, tuberculosis, and fungus occurred with almost equal frequency.
The most common cause of malignancy-related superior vena cava syndrome is bronchogenic carcinoma, which accounts for nearly 80% of cases.
Lymphoma accounts for approximately 15% of cases.
Other cases have various causes, including infectious and catheter-related etiologies. Increasingly, dialysis catheters [2] and pacemaker leads [3] are becoming associated with superior vena cava syndrome due to thrombosis.
Epidemiology
United States data
Superior vena cava syndrome is chiefly associated with malignancy. Currently, 80-90% of patients with superior vena cava syndrome have an associated malignancy as the cause. [4, 5] This contrasts with studies in the early 1950s in which a large proportion of cases were nonmalignant. Infectious causes (eg, syphilis, tuberculosis) have decreased because of improvements in antibiotic therapy. Of the nonmalignant causes of superior vena cava syndrome, thrombosis from central venous instrumentation (catheter, pacemaker, guidewire) is an increasingly common event, especially as these procedures become more common.
International data
In developing countries, nonmalignant causes of superior vena cava syndrome continue to constitute a significant percentage. Still, superior vena cava syndrome occurs infrequently in the general population.
Race- and age-related demographics
Superior vena cava syndrome has no racial predilection. However, because of poorer access to adequate health care, some socioeconomic groups have a disproportionately greater representation.
Because most superior vena cava syndromes are caused by bronchogenic carcinoma, the age distribution is skewed strongly toward elderly persons. Nonmalignant causes, as well as lymphoma, tend to affect younger people more than malignancy-associated superior vena cava syndrome. The age range reported in one study was 18-76 years, with a mean age of 54 years. [6]
Prognosis
Superior vena cava syndrome (SVCS) is associated with malignancy. The prognosis for relief of superior vena cava syndrome symptoms is good with radiation therapy. Symptoms usually decrease within 1 month of the onset of radiation therapy. However, the ultimate prognosis is associated with the underlying malignancy itself.
The prognosis for superior vena cava syndrome not associated with malignancy is excellent because most of these causes are infectious and respond to appropriate antibiotic therapy.
Recently, management of superior vena cava syndrome by internal jugular to femoral vein bypass has been described. [7] This may help improve symptoms of patients with malignancy.
Morbidity/mortality
Malignant mediastinal tumor accounts for more than 80% of cases of superior vena cava syndrome. [4] Even when treated with radiation, only 10% of these patients are alive 30 months after presentation. However, patients with superior vena cava syndrome due to a malignant cause survive only 30 days without radiation.
Complications
Total superior vena cava (SVC) obstruction is rare. Potential causes include indwelling catheters. Thrombolysis must be considered.
Airway compromise is unusual but may result from extrinsic compression of the superior vena cava or the trachea by the tumor mass.
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Superior Vena Cava Syndrome in Emergency Medicine. Patient with a 4-week history of increasing facial edema and known lung cancer.
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Superior Vena Cava Syndrome in Emergency Medicine. Chest radiograph of a patient with known superior vena cava syndrome (SVCS) and bronchogenic carcinoma (CA).
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Superior Vena Cava Syndrome in Emergency Medicine. Chest radiograph of a 50-year-old woman with complaint of shortness of breath and facial swelling. No previous history of cancer but 30 pack-year history.
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Superior Vena Cava Syndrome in Emergency Medicine. CT scan of the same 50-year-old woman in the previous image with an initial presentation of shortness of breath and facial swelling. This shows a large tumor mass in the right mediastinum nearly surrounding the right main stem bronchus and partially occluding the superior vena cava.
