Superior Vena Cava Occlusive Disease

Malignant Obstruction

Despite the rise in benign etiologies, most obstructions of the SVC are still due to malignancy. Lung cancer is the underlying etiology in approximately 78%–85% of cases of malignant stenosis with non–small cell lung cancer being the most common type followed by small cell lung cancer. Other etiologies include mediastinal lymph node enlargement caused by metastases from intrathoracic or extrathoracic malignancies, malignant lymphoma or Hodgkin disease, thymoma, mesothelioma, and tracheal malignancies. Compression of the SVC may be the result of external compression by the primary malignancy, lymphadenopathy, or, less commonly, direct invasion.

The traditional methods of treatment of SVC obstruction secondary to malignancy were radiation, chemotherapy, or a combination of both. Although effective in about 90% of cases this therapy can take time before a clinical effect is seen and can have a recurrence rate of 20% even when the maximum permissible dose of radiation is used. Radiation therapy has several downsides including causing localized edema, which may in the short term increase the patient’s symptoms, risk of long-term fibrosis, and risk that the cumulative dose will be reached before symptoms resolve. Corticosteroids have been used to treat acute SVC syndrome caused by lymphoma or thymoma, but they have not been shown to be effective in other types of malignancy.

Benign Obstruction

SVC syndrome was first reported in 1757, at which time it was most commonly due to infection from either syphilis, causing thoracic aortic aneurysm, or tuberculosis causing mediastinal adenopathy. Although malignancy has since been recognized as the most common etiology, recently there has been an increase in the prevalence of benign SVC obstruction because of the increased use of central venous catheters and pacemakers. One study has reported 40% of cases of SVC syndrome now to be due to benign etiologies. The other common causes of benign stenosis are mediastinal fibrosis, surgery, infection, and postradiation changes.

Indications For Intervention

Traditionally, patients with acute malignant SVC syndrome were treated with radiation and chemotherapy, and endovascular treatment was reserved for those who did not respond. However, several studies have advocated the use of endovascular therapy and stenting as first-line therapy because it provides immediate relief of the obstruction and does not preclude further treatment with chemotherapy or radiation. Acute thrombosis of benign lesions or chronic SVC stenosis should also be considered for catheter-based intervention and stenting. Patients with asymptomatic SVC syndrome may also benefit from intervention in the setting of a central venous access placement or upper extremity fistula creation.

Contraindications

Contraindications to venous stenting include extensive chronic venous thrombosis, anatomic considerations predisposing to severe technical difficulty, and advanced disease in preterminal patients. Lymphoma causing SVC syndrome is a relative contraindication to stenting because this tumor is highly sensitive to radiation and chemotherapy and shrinks rapidly with onset of therapy. Additionally, stenting in patients with a long life expectancy is a relative contraindication because of the high rate of future stent occlusion.

As a general rule, venous access sites should be preserved if possible. The ostia of large tributaries of the caval system, such as the jugular veins, should not be deliberately covered by a stent to preserve the possibility of further catheterization if necessary. However, the exception to the rule is the ostium of the azygos vein, which is routinely covered when stenting the SVC, generally without clinical side effects. Impaired venous flow, such as secondary to limb paralysis, is a relative contraindication to stent placement in the SVC tributaries. Occasionally, transmural venous tumor invasion caused by lymphoma or bronchogenic carcinoma is present. Because uncovered stents may be ineffective in such cases, placement of covered stents is indicated in these infrequent cases.

These procedures can often be done under moderate sedation; however, patients should be able to cooperate during the procedure. Some patients with severe SVC syndrome may have difficulty lying flat. Under these circumstances, the procedure should be undertaken with the patient under general anesthesia. A minority of patients will have simultaneous tracheobronchial narrowing because of malignant compression. Stenting of the airways should precede management of the caval obstruction in such patients.

Equipment

• Sheaths large enough to accommodate venous stents, and long enough to reach the SVC.

• Standard braided angiographic and crossing catheters, and hydrophilic or specialty guidewires for crossing lesions. Graduated (“marker”) pigtail catheters are useful internal references when making measurements.

• Working guidewires of sufficient length to allow potential through-and-through access.

• Regular and high-pressure angioplasty balloons.

In the setting of a more complex reconstruction, sharp recanalization with a snare or balloon target can be employed.

Many stents are used off-label in the SVC such as self-expanding wall stents (Boston Scientific, Marlborough, MA), large biliary and arterial stents, balloon-expandable Palmax XL (Cardinal, Dublin, OH) stents, and, more recently, dedicated venous stents from Bard (New Providence, NJ), Boston Scientific, Cook (Bloomington, IN), and Medtronic (Minneapolis, MN).

Technique