Persistent left superior vena cava

A PERSISTENT LEFT superior vena cava draining into the coronary sinus is usually of little hemodynamic consequence, but it may become significant during cardiac catheterization, transvenous pacemaker insertion, cardiac surgery, surgery of the left mediastinum, or when it is used as a route for pulmonary artery (PA) flow-directed catheter placement.1-3 A case is described in which this congenital anomaly was found during thoracotomy. Some clinical aspects, including methods of detecting the presence of a left superior vena cava, are reviewed. Problems relating to the placement of a pulmonary artery flotation catheter in such a patient, and to the interpretation of collected data, are discussed.