Interaction between atrial pacing lead and epicardial ventricular wire resulting in unintended ventricular capture by pacemaker atrial output.

Abstract

A 65‐year‐old man with a history of coronary artery disease underwent coronary artery bypass grafting in 1997 and 1998. He also received a permanent dual chamber pacemaker implantation during the second bypass surgery for complete heart block. He presented a year later to our pacemaker clinic for follow‐up. Initial ECG showed ventricular capture by pacemaker atrial output (bottom tracings, left side). When the atrial output was decreased by 0.5V, normal atrial and ventricular pacemaker function was restored (bottom tracings, right side). A chest X‐ray revealed an active fixation atrial lead implanted to the right atrium and a passive fixation lead to the ventricle. There was no apparent insulation failure of either lead by X‐ray or by impedance measurements. An epicardial pacing lead implanted during bypass surgery for temporary postoperative pacing was not completely removed. The proximity between the retained epicardial wire and the screw of the active fixation atrial lead (arrow) support the hypothesis that the atrial output was conducted by the retained epicardial wire into the ventricles, resulting in unintended ventricular capture by the atrial output. However, we could not exclude the possibility that the atrial lead directly resulted in ventricular capture due to its proximity to the AV grove.