Repetitive ICD Discharges During an Ambulance Ride: An Unusual Pacemaker‐ICD Interaction

Pacemaker-ICD adverse interactions can be due to incompatibilities between device configurations or to malfunction of the devices or lead systems.We present a case that illustrates the occurrence of both types of interactions in the same patient.One of these had an uncommon presentation.We analyze the mechanism of the interactions between the pacemaker and ICD in our case and review the mechanisms of these interactions in general.Case Report A 58-year-old man presented to another institution in Decemher 1997 with moderately symptomatic sustained ventricular tachycardia [VT) at a rate of 145 beats/min.He bad a history of coronary artery disease with LV ejection fraction of 40%.He initially presented with VT in February 1995 at which time he underwent ICD implantation (Ventak Mini model 2901 [CPI.St. Paul, MN.USA] witb Endotak lead model 0095).In July 1997 he developed medically refractory atrial fibrillation with rapid ventricular response that required AV nodal ahlation witb a concomitant pacemaker implant (CPI Vigor model 1232, [CPI, St. Paul, MN, USA]) with Medtronic 5068 leads (Medtronic, Inc., Minneapolis, MN, USA) in the atrium and high right ventricular septum).On presentation, the defibrillator was found programmed to a single detection zone at a cut-off rate of 160 beats/min.The pacemaker was found pro-