Superior vena cava syndrome: etiology, diagnosis, and treatment.

Superior vena cava (SVC) syndrome is a critical condition in which an intrathoracic mass lesion compresses the SVC and promotes the development of head and upper body edema and cyanosis. SVC syndrome develops in 10% of patients with a right-sided malignant intrathoracic mass lesion. Diagnostic evaluation and emergency therapy are always necessary to assess and alleviate airway obstruction, cerebral venous hypertension and symptoms secondary to mediastinal compression. Radiation therapy and venous bypass of the obstructed SVC are both used successfully as early treatment. Although radiation therapy to the malignant process may provide initial decompression, a more sustained decrease in venous pressure occurs in patients who also undergo decompressive SVC surgical bypass. SVC bypass should be considered early in the course of patients with profound cerebral or laryngeal edema, patients with extensive thrombosis of the SVC, and in rare patients afflicted with severe venous hypertension and in whom a tissue diagnosis requires a mediastinal exploration.