Superior vena cava obstruction
Introduction
Superior vena cava (SVC) obstruction is an oncological emergency caused by compression of the SVC. It is most commonly associated with lung cancer.
Epidemiology
- Incidence: 4.00 cases per 100,000 person-years
- Peak incidence: 70+ years
- Sex ratio: 1:1
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Causes
- common malignancies: non-small cell lung cancer, lymphoma
- other malignancies: metastatic seminoma, Kaposi's sarcoma, breast cancer
- aortic aneurysm
- mediastinal fibrosis
- goitre
- SVC thrombosis
Pathophysiology
The sign & symptoms of superior vena cava obstruction are caused by obstruction of venous return from head & neck, upper thorax and upper limbs via superior vena cava. Obstruction can be caused by external compression and or internal blockage by a thrombus.
Complications:
Acute untreated SVCO can cause sudden death.
- The presentation can be either subacute/chronic or acute ( in rapidly growing tumours).
- Most cases are subacute/chronic. In these cases, venous collaterals develop and venous pressure is not extremely raised. Patients in these cases don’t need urgent treatment.
- In acute cases, venous pressure increases to dangerous levels and complications can develop.
Complications:
- Severe laryngeal oedema & airway obstruction
- Cerebral oedema causes neurological signs
- Low cardiac output leads to hypotension
- Pulmonary embolism if the intravascular thrombus is present
Acute untreated SVCO can cause sudden death.
Clinical features
Features
Investigations
Diagnosis can be made on clinical grounds in patients with overt symptoms and signs. However, further investigations are required to confirm the diagnosis and to identify the underlying aetiology.
- Chest x-ray
- widened mediastinum or mass lesion in the lung
- CT thorax
- Most useful imaging test
- Done with intravenous contrast
- Helps establish the diagnosis; shows the exact location, severity, and associated pathology (e.g., malignancy or intravascular thrombosis)
- Helpful in obtaining a tissue diagnosis by CT-guided biopsy
- MRI chest
- Useful in patients with a history of contrast allergy or those at risk of contrast-induced worsening of renal function
- Contraindicated in patients with pacemakers and defibrillators
- Doppler ultrasound of upper extremities
- Useful non-invasive screening test
- Helps in identification of venous thrombosis or obstruction
- Presence of monophasic flow in the superior vena cava (SVC) or loss of respiratory variation on Doppler ultrasound can suggest superior vena cava obstruction (SVCO)
- Venography
- Invasive test, usually performed by venous catheterisation through the femoral vein and injection of contrast dye in the SVC
- Defines site and extent of SVC obstruction and collateral pathways
- Does not provide information about lung or mediastinal pathology
- Not usually required for diagnosis due to improvements in CT and MRI, but useful for endoscopic interventions
- Biopsy
- Obtaining tissue diagnosis is important to confirm or out rule the presence of malignancy
- Different techniques can be used to get tissue or cells for diagnosis, for example, bronchoscopy, transthoracic needle-aspiration biopsy, mediastinoscopy or a biopsy from supraclavicular or cervical lymph nodes
Management
Once the diagnosis has been established, a malignant or non-malignant cause of SVCO must be determined, as treatment options differ. Treatment usually involves relieving the symptoms of obstruction and treating the underlying aetiology.
- Symptom relief
- Elevation of the head of the bed
- Supplemental oxygen
- Corticosteroids and diuretics are used to relieve symptoms although evidence for their efficacy is lacking
- Radiotherapy or percutaneous stenting can be used in the emergency situation (eg, reduced cardiac output, cerebral or laryngeal oedema)
- Urgent treatment with radiotherapy and corticosteroids should be used only for life-threatening situations. It should be deferred otherwise, due to interference with subsequent histopathological diagnosis
- Malignant obstructions
- Selection of therapy will depend on the type of malignancy, staging, and histopathology
- Most malignant tumours causing SVCO are sensitive to radiotherapy
- Chemotherapy is an effective option for treatment of lung cancer, lymphomas, and germ cell tumours
- Surgery for tumours resistant to chemo and radiotherapy e.g. thymoma
- Benign obstructions
- Benign causes are managed with percutaneous stenting
- Bypass grafting
- Anticoagulation & intravascular thrombolysis for thrombosis
- Treatment of underlying infectious aetiology
- Palliative therapy
- This includes palliative radiotherapy, chemotherapy or corticosteroids (for lymphomas and thymomas), endovascular stents, or rarely bypass surgery
Prognosis
Prognosis usually depends on the underlying aetiology, with poor prognosis for malignant conditions.
- Malignant aetiology
- In patients with treatment-responsive malignancies, superior vena cava obstruction does not necessarily signify an adverse outcome
- In patients with cancer resistant to chemotherapy and radiotherapy, development of superior vena cava obstruction is associated with poor prognosis
- Benign aetiology
- Prognosis is generally very good
- In some cases there might be a need to repeat stenting or surgery