Superior vena cava obstruction
Introduction
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
- 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 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
Investigations
- 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
- 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
- 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