Implantable Cardioverter-Defibrillator Shock: Appropriate or Inappropriate?


  • Disclosures: Drs. Baranchuk, Simpson, and Redfearn have received honoraria from Medtronic, Boston Scientific, and St. Jude Medical to deliver conferences.

Address for correspondence: Adrian Baranchuk, M.D., F.A.C.C., 76 Stuart St, Kingston, ON, Canada K7L 2V7. Fax: (613) 548-1387; E-mail:


A 76-year-old female with a single chamber implantable cardioverter-defibrillator implanted for secondary prevention was referred due to multiple discharges. The device was programmed for ventricular tachycardia (VT) detection at 400 ms, fast VT detection at 280 ms, and ventricular fibrillation detection at 320 ms. Antitachycardia pacing (ATP) during charge was enabled. Interrogation revealed a VT episode with a mean cycle length of 270 ms, which was successfully terminated with ATP during charge. Seconds later, the device delivered a shock. This case illustrates the importance of understanding programming algorithms as part of troubleshooting when facing a scenario of device discharge.

Ann Noninvasive Electrocardiol 2010;15(2):181–183