Superior Vena Cava (SVC) Obstruction

OVERVIEW

Superior vena cava (SVC) obstruction impairs venous return through the SVC to the right atrium and has many causes, usually mediastinal masses or complications of SVC lines

ANATOMICAL CONSIDERATIONS

• SVC is the principle venous drainage to head, neck and upper extremities
• the major collateral is the azygos vein which joins SVC posteriorly over the right main bronchus and drains the posterior thorax
• if obstruction distal to azygos insertion on the SVC,  compensation occurs
• if obstruction proximal to azygos then flow must bypass the SVC and return via the internal mammary, superficial thoracoabdominal, vertebral venous system to the inferior vena cava (IVC), resulting in very high pressures

CAUSES

• indwelling SVC catheters: thrombosis, stricture formation, vessel injury and hematoma
• lung cancer (90% in patients without SVC catheters)
• retrosternal tumours e.g. lymphoma, thymoma, dermoid, other malignancies
• retrosternal goitre
• massive mediastinal lymphadenopathy e.g. breast cancer, other malignancies, granulomatous disease
• aortic aneurysm

CLINICAL FEATURES

History

• oedema to face, neck, upper torso, upper limbs
• cough, dyspnea
• hoarseness and dysphagia
• syncope and headaches
• chest pain

Examination

• SVC catheters or scars from previous lines
• plethoric and facial cyanosis
• periorbital and facial oedema, exophthalmos, conjunctival injection, and venous dilatation in the fundi
• distended non-pulsatile neck veins
• neck oedema: stridor, Horner syndrome, hoarse voice
• positive Pemberton sign
• oedema of upper extremities
• dilated venous collaterals (e.g. chest)
• pleural effusions
• cardiac tamponade
• features of the underlying cause

INVESTIGATIONS

Laboratory

• blood tests for systemic disease and organ failure
• sputum cytology

Imaging

• CXR
• HR CT: thoracic neoplasm, retrosternal thyroid, mediastinal fibrosis, thrombosis from intravascular device, aneurysm
• MRI

Other

• bronchoscopy
• TTE
• mediastinoscopy + biopsy
• node biopsy
• bone marrow aspiration

MANAGEMENT

Goals:

1. diagnose cause
2. treat obstruction
3. supportive care

Specific therapy is determined by aetiology

• steroids
• chemotherapy
• radiotherapy (30 Gr in 10 fractions)
• thrombosis: thrombolytic, stent, anticoagulation
• surgical resection and reconstruction
• IV access in IVC territory

Prepare for:

• cardiovascular collapse (tamponade)
• central airway obstruction
• laryngeal dysfunction
• associated respiratory failure

Such catastrophic complications will likely need operative intervention +/- radiotherapy — consider palliation where appropriate