ICD hardware failure associated with multiple internal shocks

The delivery of 37 shocks by an ICD within 20 minutes, in response to T wav e oversensing during atrial flutter, resulted in several manifestations of undesirable device behavior. The generator reverted to backup mode, and dis abled automatic capacitor reformation, therapy delivery, and automatic gain control. Postexplant analysis of the device revealed damage to the high vo ltage output section of the circuitry consistent with excessive electrical stress. In rare circumstances, multiple infernal discharges can result in s erious clinical anomalies in ICD behavior, and possibly in an increase in s usceptibility to circuitry damage.