DEFINITION
The SVC syndrome refers to a constellation of symptoms and signs secondary to obstruction of blood flow through the SVC, producing severe reduction in venous return from the head and neck, upper trunk and extremities. The obstruction is due either from invasion or external compression of the SVC, thrombosis within the SVC, or both.
ETIOLOGY
The epidemiology of underlying causes of SVC obstruction, continues to evolve, with recent new trends :
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Before the discovery of antibiotics, the most common etiologies were syphilitic aortic aneurysms (original description by William Hunter in 1757), fibrosing mediastinitis from untreated histoplasmosis, and compression from tuberculous lymphadenitis.
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In the present day, the most common etiology is malignancy (60%–85%), followed by benign causes (15%–40%).
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There is an increasing incidence of benign causes due to increased use of intravascular devices. This distinct trend is well illustrated in the most recently published series ( Table 28-1 ).
TABLE 28-1 ▪
ETIOLOGY UNDERLYING SUPERIOR VENA CAVA SYNDROME
Condition
Rice, et al 4 1996–2001 n = 78 (%)
Yellin, et al 3 1972–1987 n = 63 (%)
Malignant/Tumor
Small cell lung cancer
22
6
Non–small cell lung cancer
24
41
Lymphoma
8
21
Germ cell tumors
3
2
Thymoma
–
3
Esophageal cancer
–
2
Metastatic tumors (e.g., breast)
6
Benign/Nontumor
Portacath/Hickman
22
–
Dialysis catheter
5
2
Fibrosing mediastinitis
8
5
SVC thrombosis
–
SVC, superior vena cava.
Note: ≤2%: Pacer wire, aortic dissection, pseudotumor, S/P Mustard operation, Behcet’s syndrome, retrosternal goiter, idiopathic.
Etiology—Key Facts
Malignancy
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Bronchogenic carcinoma is the most common cause of SVC syndrome, occurring in 2% to 4% of patients overall during the disease course:
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Small cell carcinoma:
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Higher prevalence of SVC obstruction compared with non–small cell lung cancer (6%–20% of patients; central location)
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SVC obstruction has been associated with a higher incidence of brain metastases.
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Non–small cell carcinoma:
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Large cell and other centrally located tumors are the most common types associated with SVC obstruction.
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SVC obstruction is a poor prognostic indicator.
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Lymphoma
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Non-Hodgkin’s lymphoma:
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Most common group of lymphomas causing SVC obstruction, primarily due to lymph node compression
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Diffuse large cell and lymphoblastic most commonly associated subtypes
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Primary mediastinal B-cell lymphoma has been associated with SVC obstruction as a presenting feature, in 57% of cases
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Hodgkin’s lymphoma:
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Much rarer (7 times), despite bulky mediastinal and hilar adenopathy in some subtypes
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Germ cell tumors
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2% to 3%
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Primary mediastinal germ cell tumors: all types except mature teratoma; SVC syndrome in 20% of a series cohort
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Thymus tumors
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Includes thymoma, invasive thymoma, thymic carcinoma
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Other malignancies
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Solid tumors with mediastinal nodal metastases (breast cancer most common; thyroid, renal, rectal)
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Esophageal cancer
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Granulocytic sarcoma associated with acute or chronic myeloid leukemia
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Benign Causes
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Intravascular devices
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Increasing incidence; 25%
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Indwelling venous catheters: SVC obstruction has been linked to Port-a-Cath, dialysis catheters, and Hickman and other central venous catheters.
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Development of SVC obstruction with indwelling catheters has been associated with suboptimal extension of catheters to the SVC/RA junction.
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Pacemaker/implantable cardioverter defibrillator wires—proposed risk factors include:
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Presence of prior temporary pacing lead, more than one pacer lead, retention of a severed lead, previous lead infection, and dual coil leads
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Trauma to the vessel wall during insertion
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Prior venous thrombosis; hormonal therapy
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Fibrosing mediastinitis
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2% to 10% of several series
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Excessive host response to infectious or noninfectious agent that involves mediastinal lymph nodes and that culminates in an excessive sclerosing process, with compressive of regional structures (SVC, pulmonary arteries and veins, airways, esophagus).
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Most commonly due to Histoplasma capsulatum infection.
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Can also be caused by tuberculosis, actinomycosis, blastomycosis, aspergillosis, nocardiosis, and bancroftian filiariasis.
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Other
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Postradiation
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Primary SVC thrombosis
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Sarcoidosis
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Behcet’s disease
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Coronary artery bypass
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Sclerosing cholangitis
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See Table 28-1
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CLINICAL FEATURES
Symptoms and Signs
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May occur as presenting manifestations of the underlying disorder, at any time during its course, and occasionally following surgical or other manipulation that disturbs adaptive collateral flow.
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With SVC obstruction, venous collaterals form to promote venous return to the right atrium ( Fig. 28-1 ).
Figure 28-1
A, Transaxial computed tomography (CT) section showing compression of superior vena cava (SVC) by tumor together with a profusion of collaterals. B, CT reconstructed oblique view showing focal narrowing of SVC and prominent collateral vessels.
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With SVC syndrome, proximal venous pressures remain high despite collateral formation in the azygos, internal mammary, lateral thoracic, paraspinous, hemiazygous, intercostal, and esophageal venous systems.
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With high obstruction, collaterals drain into the azygos vein (most efficient decompressor). Obstruction below the azygous confluence drains to the inferior vena cava via hemiazygous or chest wall veins (less efficient).
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The rapidity with which SVC obstruction occurs affects the severity of the syndrome. Rapid development allows less time for adaptive collaterals to form, and thus greater severity.
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The duration of symptoms before diagnosis depends on the underlying cause or condition. In one series, 43% presented in less than 1 month and 50% after 1 to 6 months.
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Presenting symptoms and signs are outlined in Table 28-2 .
TABLE 28-2 ▪
PRESENTING SIGNS AND SYMPTOMS OF SUPERIOR VENA CAVA SYNDROME
Sign/Symptom
Rice, et al 4 1996–2001 n = 78 (%)
Yellin, et al 3 1972–1987 n = 63 (%)
Venous congestion head/neck
82
86
Upper extremity/trunk swelling
62
32
Dyspnea at rest
53
30
Cough
50
21
Dilated chest veins
38
NS
Chest/shoulder pain
19
6
Facial plethora
18
NS
Syncope/pre-syncope/dizziness
13
NS
Headache
12
NS
Hoarseness
12
NS
Hemoptysis
9
8
Dysphagia
6
6 
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