Summary
Introduction
Compared with monophasic defibrillation, biphasic defibrillation is associated with
less myocardial stunning and earlier activation of sodium channels. We therefore hypothesised
that earlier sodium channel activation would result in earlier restoration of the
first sinus beat following elective DC cardioversion.
Methods
Adults undergoing elective DC cardioversion were randomised to receive either monophasic
or biphasic escalating transthoracic shocks. The ECG was recorded electronically during
defibrillation and the time from delivery of the shock to restoration of the first
sinus beat, measured from the beginning of the ‘P’ wave, was calculated.
Results
Seventy four patients were studied. Data were unavailable from 18 patients. There
was no demographic difference between groups. Median time to the first sinus beat
following monophasic defibrillation (n = 25) was 3.66 s (95% CI 2.55–4.61 s) and following biphasic defibrillation (n = 33) was 2.21 s (95% CI 1.76–2.56 s; P ≤ 0.0001). Linear regression confirmed that the waveform was an independent predictor
of time to restoration of sinus rhythm; P < 0.0001. The final defibrillation energy level used to achieve cardioversion was not
an independent predictor of time to restoration of sinus rhythm; P = 0.49.
Conclusion
Biphasic defibrillation for elective DC cardioversion achieved more rapid restoration
of the first sinus beat compared with a monophasic waveform. Waveform, but not energy
level that achieved defibrillation, was an independent predictor of time to restoration
of the first sinus beat. The mechanism for this may be related to the earlier reactivation
of sodium channels associated with the biphasic waveform.
Keywords
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Article info
Publication history
Accepted:
July 26,
2005
Received in revised form:
July 13,
2005
Received:
April 22,
2005
Footnotes
☆A Spanish translated version of the summary of this article appears as Appendix in the online version at 10.1016/j.resuscitation.2005.07.021.
Identification
Copyright
© 2005 Published by Elsevier Inc.
