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document
The influence of ventricular fibrillation duration on defibrillation efficacy using biphasic waveforms in humans . OBJECTIVES The purpose of this study was to prospectively investigate the influence of ventricular fibrillation ( VF ) durations of 5 , 10 and 20 s on the defibrillation threshold ( DFT ) during implantable cardioverter-defibrillator ( ICD ) implantation . BACKGROUND Although the DFT using monophasic waveforms has been shown to increase with VF duration in humans , the effect of VF duration on defibrillation efficacy using biphasic waveforms in humans is not known . METHODS Thirty patients undergoing primary ICD implantation or pulse generator replacement were randomly assigned to have the DFT determined using biphasic shocks at two durations of VF each ( 5 and 10 s , 10 and 20 s or 5 and 20 s ) . RESULTS There was no statistically significant difference in the mean DFT comparing VF durations of 5 s ( 9.5+/-6.0 J ) and 10 s ( 10.8+/-7.0 J ) ( p=0.4 ) . The mean DFT significantly increased from 10.9+/-6.1 J at 10 s of VF to 12.6+/-5.6 J ( p=0.03 ) at 20 s of VF , and from 7.0+/-3.5 J at 5 s of VF to 10.5+/-6.3 J ( p=0.04 ) at 20 s of VF . An increase in the DFT was observed in 14 patients as VF duration increased . There were no clinical characteristics that differentiated patients with and without an increase in the DFT . CONCLUSIONS Defibrillation efficacy decreases with increasing VF duration using biphasic waveforms in humans . Ventricular fibrillation durations greater than 10 s may negatively affect the effectiveness of ICD therapy .
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Intervention_Physical
DFT determined using biphasic shocks
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Outcome_Other
defibrillation efficacy
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Outcome_Other
defibrillation threshold ( DFT )
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Outcome_Other
DFT using monophasic waveforms
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Outcome_Other
mean DFT
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Outcome_Other
DFT
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Outcome_Other
DFT
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Outcome_Other
DFT
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Outcome_Other
Defibrillation efficacy
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Outcome_Other
effectiveness of ICD therapy
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Participant_Sample-size
Thirty
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Participant_Condition
patients undergoing primary ICD implantation or pulse generator replacement
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Participant_Sample-size
14