Implantation of a biventricular pacing system in a patient with a coronary sinus not communicating with the right atrium.

Intubation of the coronary sinus failed during implantation of a biventricular pacing system. An angiogram of the left coronary artery showed in the venous phase a coronary sinus not communicating with the right atrium. The coronary sinus was draining into a persistent left superior vena cava communicating with the left subclavian vein. The coronary sinus lead was successfully implanted through the persistent left superior vena cava, whereas the atrial and ventricular leads were implanted through the right superior vena cava in a conventional way.