Superior vena cava syndrome overview

Superior Vena Cava Syndrome Microchapters
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Overview
Historical Perspective
Pathophysiology
Causes
Differentiating Superior Vena Cava Syndrome from Other Diseases
Epidemiology and Demographics
Risk Factors
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Natural History, Complications and Prognosis
Diagnosis
Staging
History and Symptoms
Physical Examination
Laboratory Findings
Chest X Ray
CT
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Superior vena cava syndrome (SVCS) is an array of symptoms caused by the impairment of blood flow through the superior vena cava (SVC) to the right atrium. Symptoms that prompt suspicion of this syndrome include dyspnea, coughing, and swelling of the face, neck, upper trunk, and extremities. In rare instances, patients may complain of hoarseness, chest pain, dysphagia, and hemoptysis. Physical signs that may be noted on presentation are neck vein distention, thoracic vein distention, edema of the face or upper extremities, plethora, and tachypnea. Rarely, cyanosis, Horner syndrome, and a paralyzed vocal cord may also be present.

Historical Perspective

The Scottish obstetrician and anatomist, William Hunter, first described the superior vena cava syndrome in 1757, noting it as a complication of a syphilitic aortic aneurysm. In the past, it was a medical emergency and empiric radiation was given to shrink the tumor. With the advent of better medical therapy for some lung cancers and lymphoma and the low morbidity associated with diagnostic procedures, this approach has fallen out of favor.

Pathophysiology

The superior vena cava (SVC) is the major blood vessel for drainage of venous blood from the head, neck, upper extremities, and upper thorax to the heart. Obstruction of the superior vena cava (SVC) may be caused by neoplastic invasion of the venous wall associated with intravascular thrombosis, enlarged nodes, enlarged ascending aorta, or more simply, by extrinsic pressure of a tumor mass against the thin-walled superior vena cava (SVC) which leads to the development of SVC syndrome.

Causes

Superior vena cava syndrome may be caused by obstruction of the superior vena cava (SVC) by neoplastic invasion of the venous wall associated with intravascular thrombosis, enlarged nodes, enlarged ascending aorta, or more simply, by extrinsic pressure of a tumor mass against the thin-walled superior vena cava (SVC).

Differentiating Superior Vena Cava Syndrome from other Diseases

Superior vena cava syndrome should be differentiated from other causes of dyspnea and jugular venous distention, such as, cardiac tamponade, chronic obstructive pulmonary disease, mediastinitis, pneumonia, acute respiratory distress syndrome, syphilis, and tuberculosis.

Epidemiology and Demographics

Most SVC syndromes in the present day are related to malignancy. An underlying malignancy is found in approximately 90% of patients.

Diagnosis

History and Symptoms

SVC syndrome usually presents more gradually with an increase in symptoms over time as malignancies increase in size or invasiveness. Symptoms occur when something blocks the blood flowing back to the heart. They may begin suddenly or gradually, and may worsen when you bend over or lie down. The most common symptoms are shortness of breath (dyspnea) and swelling of the face, neck, trunk, and arms.

Chest X Ray

Blockage of the SVC may be visible on chest x ray and it is also useful to detect lung cancer.

CT

Blockage of the SVC may be visible precisely on CT scan of the chest and it is also useful in evaluating source and extent of a neoplasm.

MRI

Blockage of the SVC may be visible precisely on MRI of the chest and it is also useful in evaluating source and extent of a neoplasm.

Ultrasound

Doppler ultrasound may be valuable in assessing the site and nature of the obstruction in SVC syndrome. Venous patency and the presence of thrombi can also be assessed by using contrast and rapid scanning techniques.

Other Imaging Findings

SVC syndrome may also affect the findings of radionuclide ventriculography and liver scan.

Treatment

Medical Therapy

The treatment of SVC syndrome depends on the etiology of the obstruction, the severity of the symptoms, the prognosis of the patient, and patient preferences and goals for therapy.

Radiation Therapy

If the obstruction of the SVC is caused by a tumor that is not sensitive to chemotherapy, radiation therapy should be given. Treatment with larger fractions of radiation is thought to be beneficial in developing a rapid response. One study shows, however, that there is no obvious need for large radiation fraction sizes for the first few radiation treatments as was previously believed. Many fractionation schemes have been used, with doses ranging from 30 Gy in 10 fractions to 50 Gy in 25 fractions. Relief of symptoms in small cell lung cancer is reported to be 62% to 80%, whereas in non-small cell lung cancer, approximately 46% of the patients experienced symptomatic relief. In one study, more than 90% of the patients achieved a partial or complete response with a 3-week regimen of 8 Gy given once a week for a total dose of 24 Gy.

Primary Prevention

Prompt treatment of other medical disorders may reduce the risk of developing SVC obstruction.