Persistent left superior vena cava.

Congenital venous anomalies are relatively common and some have clinical implications. An example of persistent left superior vena cava was found during a routine dissection. This vein was carefully dissected and followed to its termination in the right atrium. The same cadaver also presented four branches from the arch of the aorta. A left superior vena cava occurs in early development but disappears later. The clinical significance of such a persistent left superior vena cava assumes importance during cardiac catheterization via the left subclavian vein.