Obstruction of the superior vena cava is the cause of the outstanding symptoms in many cases of mediastinal pathologic conditions. However, isolated stenosis of this vessel is distinctly rare.
Interference with the return flow of blood to the heart through the superior vena cava may arise from a wide variety of conditions in the mediastinum or in the vessel itself.
Of these causes, aneurysm,1 almost universally of the aorta, is the most common. This lesion may compress and thereby result in slow partial mechanical obstruction of the superior vena cava and give rise to a train of symptoms due to this compression and compression of other mediastinal structures, such as the recurrent laryngeal nerves, trachea and esophagus. On the other hand, an aneurysm of the aorta may perforate into the vein, producing sudden functional stenosis of the vena cava as a result of the tremendous head pressure opposing the