Pacemaker insertion in a patient with persistent left superior vena cava.

A persistent left superior vena cava (PLSVC) is a rare and usually unnoticed congenital anomaly. However, clinicians must be conscious of its existence as a PLSVC can be associated with other anomalies of cardiovenous morphology with significant clinical implications for transvenous procedures. We report a case of a double superior vena cava with absent innominate vein found during catheterization for cardiac resynchronization pacemaker therapy implantation (CRT-P). We also describe a technique used for successful positioning of the leads into the right atrium and right ventricle.