Superior Vena Cava Syndrome

Updated by Delnora L. Erickson and Bronwyn R. Stall

BACKGROUND

What vessels form the SVC?

The right and left brachiocephalic veins join to form the SVC.

What is SVC syndrome?

SVC syndrome is extrinsic or intrinsic obstruction of blood flow through the SVC, leading to proximal congestion.

Describe the course of the SVC.

The SVC begins at the sternal angle, extends inferiorly along the right lat side of the ascending aorta, and inserts into the right atrium.

What predisposes the SVC to compression?

The SVC is a thin-walled vessel with relatively low intravascular pressure and is therefore susceptible to compression by surrounding rigid structures including enlarged LNs and the trachea, sternum, pulmonary artery, and right main stem bronchus.

What vessels form the collateral system of the SVC?

The collateral system of SVC is formed by the azygos, mammary, vertebral, lat thoracic, paraspinous, and esophageal vessels.

What vessels join to form the azygos vein?

The right subcostal and right ascending lumbar veins coalesce to form the azygos vein.

What is the most common cause of SVC syndrome?

Malignancy is the most common cause of SVC syndrome accounting for ∼60% of cases. Malignancy previously accounted for 90% of cases, but with increased use of implantable intravenous devices (i.e., central venous catheters, pacemaker leads), this has decreased. (McCurdy M et al., Crit Care Med 2012)

Name 5 benign causes of SVC syndrome.

Benign causes of SVC syndrome:

1. Catheter-induced thrombosis

2. Chronic mediastinitis

3. Retrosternal goiter

4. CHF

5. Aortic aneurysm

Name 6 cancers most commonly associated with SVC syndrome, in decreasing order of incidence.

Cancers associated with SVC syndrome:

1. Non–small cell lung cancer (NSCLC): 50%

2. Small cell lung cancer (SCLC): 22%

3. Lymphoma: 12%

4. Mets: 9%

5. Germ cell tumors: 3%

6. Thymoma: 2%

(Wilson L et al., NEJM 2007)

Are NSCLC or SCLC pts more likely to develop SVC syndrome?

SCLC pts are more likely to develop SVC syndrome than NSCLC pts b/c of their propensity toward rapid growth in central airways.

What is the most common cause of SVC syndrome in pts <50 yo?

In pts <50 yo, the most common cause of SVC syndrome is lymphoma.

Which types of NHL are associated with SVC syndrome?

NHL types associated with SVC syndrome:

1. Diffuse large B-cell lymphoma

2. Lymphoblastic lymphoma

3. Primary mediastinal B-cell lymphoma with sclerosis

What is the typical duration of Sx prior to presentation with SVC syndrome?

Pts with SVC syndrome may have Sx over days to wks but usually present within 1 mo of onset.

Do most pts presenting with SVC syndrome have a prior cancer Dx?

No. Most pts presenting with SVC syndrome do not have a prior cancer Dx.

Why is SVC syndrome considered an emergency?

SVC syndrome may cause airway obstruction and cerebral edema; however, severe Sx are uncommon, and life-threatening Sx are rare.

What are the common presenting Sx of SVC syndrome?

Presenting Sx of SVC syndrome:

1. Face and neck swelling

2. Upper extremity swelling

3. Cough/stridor

4. Dyspnea

5. Dilated chest veins

(Rice T et al., Medicine 2006)

What is the most common Sx of SVC syndrome?

The most common Sx of SVC syndrome is facial swelling.

What physical exam findings are associated with SVC syndrome?

Signs of SVC syndrome: plethora, facial edema, jugular venous distension, and visible collateral venous drainage on the ant chest

WORKUP/STAGING

Describe the workup of SVC syndrome.

SVC syndrome workup: H&P, assessment of respiratory status, CXR and/or CT chest with contrast (best to visualize the extent of blockage), determination of the best Bx route if Dx is unknown, labs (AFP, LDH, β-HCG), and BM aspirate and Bx

Name 5 ways to obtain tissue Dx for SVC syndrome.

Methods to obtain tissue Dx in SVC syndrome:

1. Sputum cytology

2. Bx of palpable LNs

3. Bronchoscopy

4. Mediastinoscopy

5. Video-assisted thorascopic surgery

What is usually seen on CXR in SVC syndrome?

CXR findings in SVC syndrome include a widened mediastinum and the presence of a mass near the SVC.

What CT finding is closely associated with SVC syndrome?

The presence of collateral vessels is a CT finding that closely relates to SVC syndrome.

Why should RT not be given prior to a histologic Dx in SVC syndrome?

RT may obscure the histologic Dx and should be deferred until diagnostic Bx is obtained in SVC syndrome. However, empiric Tx may be considered in the setting of airway obstruction or cerebral edema.

TREATMENT/PROGNOSIS

What is the 1^st step in Tx of SVC syndrome?

The 1^st step in treating SVC syndrome is to establish a pathologic Dx, which will determine further interventions.

What Tx may be used for SVC syndrome?

SVC syndrome Tx: RT, chemo, surgery, and stents

What supportive measures can be taken to manage SVC syndrome?

Elevation of head of bed and supplemental oxygen. Diuretics can be used for cerebral edema. (McCurdy M et al., Crit Care Med 2012)

What is the role of steroids in SVC syndrome?

Steroids are frequently used in SVC syndrome, but there are limited data to support their use except in lymphoma and thymoma.

In which malignant causes of SVC syndrome is chemo 1^st-line Tx?

Chemo is the Tx of choice in SVC syndrome caused by lymphoma, germ cell tumors, and SCLC.

What is the most rapid way to manage SVC thrombosis?

The most rapid method to manage SVC thrombosis is by intraluminal stenting.

What Tx should be considered if a pt with SVC syndrome presents with thrombosis?

Use anticoagulation therapy for pts with SVC syndrome presenting with thrombosis unless contraindications are present.

Which pts with SVC syndrome require emergent Tx?

SVC syndrome pts with central airway compromise, severe laryngeal edema, or coma secondary to cerebral edema require emergent Tx.

What fractionation is used to emergently treat SVC syndrome?

Fractionation for emergent SVC Tx is 2.5–4 Gy × 3 fx. There are conflicting retrospective data on the benefit of hypofractionation.

When treating SVC syndrome, what should the RT fields encompass?

RT fields for SVC syndrome include encompassing gross Dz and adjacent nodal tissue while respecting normal tissue toxicity, esp the lungs and heart.

What should guide the total RT dose used for SVC syndrome?

The total RT dose for SVC syndrome depends on the underlying histology (i.e., lung cancers are treated to ≥60 Gy, while lymphomas are treated to 35–45 Gy).

Does SVC syndrome portend a bad prognosis?

No. The prognosis in SVC syndrome depends on the underlying cause rather than the presence of the syndrome itself. Median survival is about 6 mos for cancer-induced SVC syndrome. However, based on etiology, many will survive longer or even be cured.

What is the overall symptomatic response to RT in SVC syndrome?

The overall response rate to RT for SVC syndrome is ~60%.

Over what approximate timeline can pts expect symptom relief from RT?

Normally, response time to RT is 7–15 days, but in some cases, relief may be experienced as soon as 72 hours. (Wan J et al., Emerg Med Clin N Am 2009)

Does RT for SVC syndrome restore normal flow in the SVC?

No. RT for SVC syndrome does not generally restore normal vascular flow despite improving Sx.

What non-Tx event likely contributes to symptomatic improvement in SVC syndrome?

The development of collateral vessels largely contributes to Sx improvement in SVC syndrome.

What is the Tx if RT or chemo are not effective?

Vascular stents are recommended, with angioplasty 1^st if the lumen needs to be expanded.