Persistent left superior caval vein with absent right superior caval vein: importance of awareness.

Isolated persistent left superior caval vein is a rare anomaly of the systemic venous return. We describe an unsuccessful pacemaker implantation through the right subclavian vein, which later turned out to be due to a venous anomaly. This case and some other cases show that with the help of a multidetector computed tomography, an isolated persistent left superior caval vein is not a contraindication for subclavian approached pacemaker insertion.