Superior vena cava syndrome

Superior vena cava syndrome (SVCS) is a veno-occlusive disease that results in clinically significant impairment of venous outflow from the superior vena cava basin.

What causes superior vena cava syndrome?

78-97% of cases of SVCS in adults are caused by oncological diseases. At the same time, about half of patients with SVCS suffer from lung cancer, and up to 20% - from non-Hodgkin's lymphomas. Somewhat less often, superior vena cava syndrome occurs with metastatic breast cancer, and even less often with other malignant neoplasms affecting the mediastinum and lungs (with Hodgkin's lymphoma, thymoma or germ cell tumors, SVCS develops in less than 2% of cases).

The causes of the development of SVCS are compression of the superior vena cava, tumor invasion, thrombosis or sclerotic changes in this vessel.

Non-neoplastic superior vena cava syndrome occurs in:

• retrosternal goiter,
• purulent mediastinitis,
• sarcoidosis,
• silicosis,
• constrictive pericarditis,
• post-radiation fibrosis,
• mediastinal teratoma,
• idiopathic mediastinal fibrosis,
• In any disease, the development of SVCS is possible as a result of thrombosis and sclerosis of the vein during prolonged placement of a catheter in the superior vena cava.

In children, the cause of superior vena cava syndrome is prolonged superior vena cava catheterization, and approximately 70% of malignancy-associated SVCS cases are due to diffuse large cell or lymphoblastic lymphomas.

Symptoms of Superior Vena Cava Syndrome

The clinical symptoms and severity of the superior vena cava syndrome depend on the rate of progression and localization of obstruction, the severity of thrombosis, and the adequacy of collateral blood flow. Typically, the syndrome develops gradually over several weeks, with collateral blood flow occurring through the v azygos and anterior thoracic veins into the inferior vena cava. SVCS has specific and early symptoms.

A specific sign of SVCS is an increase in venous pressure in the superior vena cava system (head, neck, upper half of the body and arms) above 200 cm H2O.

An early symptom of the superior vena cava syndrome is engorged neck veins that do not collapse in orthostasis. The syndrome is most often detected when persistent dense swelling of the face, neck (the "tight collar" symptom), upper half of the body and shortness of breath occur. In this case, patients often complain of headache, dizziness, visual impairment, cough, chest pain, and general weakness. Dysphagia, hoarseness, swelling of the subglottic space, and swelling of the tongue can be detected.

Symptoms are aggravated by lying down and bending over.

With a significant disruption of the outflow from the veins of the head, thrombosis of the sagittal sinus and cerebral edema are possible.

In rare cases of rapid development of superior vena cava obstruction, increased venous pressure leads to increased ICP, cerebral edema, cerebral vascular thrombosis, or hemorrhagic stroke.

Diagnosis of superior vena cava syndrome

Additional instrumental examination is performed to clarify the localization and nature of the obstruction of the superior vena cava. The most informative are CT and angiography, the results of which can be used to judge the localization, length and nature of the vein obstruction (thrombosis or compression of the vein from the outside), collateral blood flow, and also to obtain a detailed idea of the tumor and its relationship to other structures of the mediastinum and chest. Clarification of the tumor localization as a result of CT allows for percutaneous transthoracic biopsy (it is safer than open biopsy or mediastinoscopy) with subsequent morphological verification of the tumor.

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Treatment of superior vena cava syndrome

General treatment measures for superior vena cava syndrome include continuous oxygen inhalation, administration of sedatives that reduce CO and pressure in the superior vena cava system, providing improvement in the condition of most patients, and bed rest (the head of the patient's bed should be elevated).

Emergency treatment is indicated in severe cases of superior vena cava syndrome with development of cerebral edema; balloon dilation of the occluded vein and its stenting are performed. If the operation is successful, immediate relief of symptoms of SVCS of any etiology is observed, quality of life improves and the possibility of additional examination, clarification of the nosology, morphological verification, adequate specific treatment (antitumor therapy, surgical treatment, etc.) is provided. Indication for emergency symptomatic irradiation of the area of tumor obstruction of the superior vena cava is limited to severe SVCS, which is accompanied by airway obstruction, spinal cord compression or rapid increase in ICP when balloon angioplasty is technically impossible.

Depending on the cause of the development of superior vena cava syndrome, treatment tactics vary.

• If the cause of SVCS is sclerosis of the vein due to prolonged presence of a catheter, balloon dilation of the occluded section is performed (sometimes with subsequent stenting). In patients with oncological etiology of SVCS, the stent remains in place for life.
• In case of occlusive thrombosis and the absence of contraindications, systemic thrombolysis (streptokinase 1.5 million IU intravenously over an hour) followed by the administration of direct anticoagulants (sodium heparin 5000 IU 4 times a day for a week) is effective.
• In case of tumor etiology of SVCS, stable improvement can be expected only from specific antitumor treatment, the prognosis directly depends on the prognosis of the oncological disease. Small cell lung cancer and non-Hodgkin's lymphomas, the two most common oncological causes of SVCS, are sensitive to chemotherapy and are potentially curable. In these diseases, resolution of SVCS symptoms can be expected within the next 1-2 weeks after the start of antitumor therapy. The syndrome subsequently recurs in 25% of patients. In case of large cell lymphomas and a significant tumor mass localized in the mediastinum, combined chemoradiation therapy is usually used. Irradiation of the mediastinal organs is indicated for most tumors that are insensitive to chemotherapy or when the morphological structure of the tumor is unknown. Relief of the symptoms of the superior vena cava syndrome occurs within 1-3 weeks after the start of radiation therapy.

Adjuvant drugs - glucocorticoids (dexamethasone) - have their own antitumor activity in lymphoproliferative diseases and can be used as "containment therapy" with a reasonable assumption of such an etiology of the superior vena cava syndrome even before morphological verification. Direct-acting anticoagulants are indicated in the treatment of thromboses caused by catheterization of central veins, especially when thrombi spread to the brachiocephalic or subclavian veins. However, in conditions of increased ICP, anticoagulant therapy increases the risk of developing intracranial hematomas, and tumor biopsy against the background of anticoagulant therapy is often complicated by bleeding from it.