Transient hyperkalemia-induced T-wave oversensing as a cause of inappropriate ICD discharges

Abstract

The present case describes a patient with an implantable cardioverter-defibrillator (ICD) who reported several ICD inappropriate discharges due to transient T-wave oversensing in the setting of acute hyperkalemia. T-wave oversensing was detected only at telemetry interrogation while T-wave amplitude at surface 12-lead electrocardiogram was normal. Oversensing was abolished by reducing potassium levels and by device reprogramming. This case report underscores the importance of identifying a potentially reversible cause of ICD inappropriate discharges and the utility of careful review of stored electrograms. <Learning objective: This case report underscores the importance of understanding the diversity of causes of implantable cardioverter-defibrillator malfunctioning and the utility of careful review of stored electrograms.>.

Keywords: Hyperkalemia; Implantable cardioverter-defibrillator; Inappropriate implantable cardioverter-defibrillator discharges; T-wave oversensing.

Fig. 1

Admission 12-lead electrocardiogram on presentation to the emergency room showed sinus rhythm with intrinsic atrioventricular conduction as well as normal T-wave amplitude.

Fig. 2

12-Lead surface electrocardiogam recorded after serum potassium level normalization showed no T-wave changes.

Fig. 3

Internal cardioverter-defibrillator (ICD) electrograms recorded during device interrogation after delivery of 11 ICD shocks showed a heart rate of 75 beats per minute with large amplitude T-waves resulting in counting both the R-waves and T-waves in the tachycardia therapy zone with delivery of inappropriate ICD shocks. The same detection pattern was noted for the other 10 inappropriate ICD shocks.

Fig. 4

Internal cardioverter-defibrillator (ICD) electrograms recorded on hospital day 4 showing the normalization of T-wave amplitudes.