Long-term evaluation of the ventricular defibrillation energy requirement

Takashi Tokano, Frank Pelosi, Matthew Flemming, Laura Horwood, Joseph J. Souza, Adam Zivin, Bradley P. Knight, Rajiva Goyal, K. Ching Man, Fred Morady, S. Adam Strickberger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Defibrillation Energy Requirements. Introduction: Defibrillation energy requirements in patients with nonthoracotomy defibrillators may increase within several months after implantation. However, the stability of the defibrillation energy requirement beyond 1 year has not been reported. The purpose of this study was to characterize the defibrillation energy requirement during 2 years of clinical follow-up. Methods and Results: Thirty-one consecutive patients with a biphasic nonthoracotomy defibrillation system underwent defibrillation energy requirement testing using a step-down technique (20, 15, 12, 10, 8, 6, 5, 4, 3, 2, and 1 J) during defibrillator implantation, and then 24 hours, 2 months, 1 year, and 2 years after implantation. The mean defibrillation energy requirement during these evaluations was 10.9 ± 5.5 J, 12.3 ± 7.3 J, 11.7 ± 5.6 J, 10.2 ± 4.0 J, and 11.7 ± 7.4 J, respectively (P = 0.4). The defibrillation energy requirement was noted to have increased by 10 J or more after 2 years of follow-up in five patients. In one of these patients, the defibrillation energy requirement was no longer associated with an adequate safety margin, necessitating revision of the defibrillation system. There were no identifiable clinical characteristics that distinguished patients who did and did not develop a 10-J or more increase in the defibrillation energy requirement. Conclusion: The mean defibrillation energy requirement does not change significantly after 2 years of biphasic nonthoracotomy defibrillator system implantation. However, approximately 15% of patients develop a 10-J or greater elevation in the defibrillation energy requirement, and 3% may require a defibrillation system revision. Therefore, a yearly evaluation of the defibrillation energy requirement may be appropriate.

Original languageEnglish (US)
Pages (from-to)916-920
Number of pages5
JournalJournal of cardiovascular electrophysiology
Issue number9
StatePublished - 1998


  • Defibrillation safety margin
  • Defibrillation threshold
  • Implantable cardioverter defibrillator

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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