Definition, Etiology, Pathogenesis Top
Superior vena cava syndrome (SVCS) is caused by the impairment of blood flow from the superior vena cava (SVC) to the right atrium.
1) Cancer (compression or infiltration of the SVC): Lung cancer (50%-80% of all cases, most frequently non–small cell lung cancer), metastatic disease (mainly breast cancer), primary mediastinal tumors (lymphoma, thymoma).
2) Nonneoplastic causes: Compression by a thoracic aortic aneurysm, chronic mediastinitis, catheter-related central venous thrombosis, right atrial tumor.
Clinical Features and Natural History Top
Typical signs and symptoms include edema and erythema or cyanosis of the face and neck, conjunctival congestion, edema of the upper extremities, persistent jugular vein distention, headache, dizziness, visual disturbances (the symptoms result from venous congestion distal to the obstruction). Dilated superficial veins of the chest are a visible sign of collateral circulation (these are observed in patients in whom SVCS develops slowly). Severe venous drainage impairment is associated with dysphagia, dyspnea, hoarseness, and stridor (often due to compression of the esophagus, trachea, or the recurrent laryngeal nerve). Pleural effusion is observed in approximately one quarter of patients.
Imaging studies (chest radiographs, computed tomography [CT], and/or magnetic resonance imaging [MRI]) show a widening of the mediastinum caused by a paratracheal, hilar, or mediastinal tumor. MRI may also provide information on the cause of SVCS in the case of thrombosis, although CT is usually easier to obtain and highly accurate.
The goal of treatment is to improve venous drainage from the regions distal to the obstruction.
1. Treatment of the underlying condition: Promptly determine the cause (including tumor histology) to start targeted therapy as soon as possible (if available). In patients with cancer:
1) Urgent mediastinal irradiation is the treatment of choice for most cancers; this leads to a symptomatic improvement within 2 weeks in ~70% of patients.
2) In patients with small cell lung carcinoma and germinal tumors, chemotherapy should be considered as the initial treatment modality; in patients with lymphoma, radiation, chemotherapy, or both should be considered.
3) Other treatment modalities: Stenting of the SVC; in the case of thrombosis, consider thrombolysis followed by anticoagulant treatment.
2. Symptomatic treatment:
1) Symptomatic treatment of dyspnea (oxygen therapy in patients with decreased SaO2; for palliative management, low-dose opioids [eg, oral or subcutaneous morphine 1-2.5 mg every 4-6 hours] or benzodiazepines [eg, sublingual lorazepam 0.5-2 mg every 8-12 hours] may help to alleviate symptoms).
2) Dexamethasone 16 to 32 mg/d IV for 7 days, then taper down the dose (this is used for malignant compression of steroid-responsive tumors, such as non-Hodgkin lymphoma, and for symptomatic management to lessen tumor-associated edema).
3) In some cases administer a loop diuretic IV.