Anomalous venous system in the human heart.

In a 2002 cadaveric dissection course, a complex manner of rare variation was found in the abnormal venous system of the heart of an 88-year-old Japanese man who died of acute pneumonia. The superior vena cava and the left and right brachiocephalic veins were normal. In this case, a complex venous system existed as follows. (1) A left superior vena cava was persistent. (2) The innominate vein was present. It went upward between the ascending aorta and the pulmonary trunk, passed through the ventral side of the bifurcation of the pulmonary trunk, and then anastomosed with the left superior vena cava. The oblique vein of the left atrium, as a fibrous bundle, was connected to the junction of the left superior vena cava and the innominate vein in the pericardium. (3) The great cardiac vein was divided into two branches. One was located at the right side of the left coronary artery, forming the origin of the innominate vein. The other extended to the coronary sinus as a normal great cardiac vein. (4) The orifice of the coronary sinus on the right atrium was obliterated. (5) The abnormal orifice existed between the left atrium and the coronary sinus. The formation process and functional significance of such venous variations are discussed.