Identification of the Pericardiophrenic Vein During Cardiac Device Implant Procedures to Prevent Extracardiac Stimulation

The primary goal of this study is to develop techniques to identify the course of the phrenic nerve in patients already undergoing cardiac resynchronization therapy (CRT) implantation or candidates for future CRT devices undergoing implantable cardioverter-defibrillator (ICD) or pacemaker implantation. Specifically, the study intends to identify the location and course of the left pericardiophrenic vein, and thus the left phrenic nerve, to guide the location for coronary vein lead placement and minimize the risk of phrenic nerve stimulation.