Isorhythmic Dissociation with Smart Sensing in a Dual‐Chamber Implantable Cardioverter Defibrillator

Abstract

Isorhythmic dissociation is an uncommon but clinically important finding in a patient implanted with a dual chamber cardioverter defibrillator (ICD) capable of SmartSensing. The surface ECG mimicked a malfunction of the pacemaker that was related to the concomitant hemodynamic deterioration. Device interrogation revealed dissociation of the intrinsic junctional and the pacemaker rhythm, which appeared at similar rates. Careful analysis of intracardiac electrograms and marker channel annotations helped to unravel the limitations for physiologic pacing.