Pacemaker implantation in patients with persistent left superior vena cava.

Implantation of a permanent pacemaker system is most commonly performed by puncturing the left subclavian vein and introducing the pacemaker lead(s) through the superior caval vein to the right atrium and/or ventricle. Occasionally, a persistent left superior caval vein is encountered peroperatively, complicating the procedure. This article describes three such patients and provides a review of the literature regarding one of the most common anomalies of the thoracic vessels.