Human persistent left superior vena cava with doubled coronary sinus.

A heart with a persistent left superior vena cava was found in a 72 year old man during routine dissection. The right superior vena cava was absent. The right brachiocephalic vein crossed over the aortic arch and its branches to the left side of the heart. This variation reportedly occurs in about 0.16% of humans. The azygos vein was, as a result, also left sided with a hemiazygos vein on the right side. The left superior vena cava drained into a channel contained with the posterior wall of the left atrium of the heart above, and parallel with the coronary sinus. The channel of the left superior vena cava opened into the right atrium above the opening of the coronary sinus. The coronary sinus may have been doubled during embryonic development. The two vessels were joined by a small connecting vessel.