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Effective defibrillation in pigs using interleaved and common phase sequential biphasic shocks
P A Guse1, D L Rollins, W Krassowska
1Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Pacing and Clinical Electrophysiology : PACE
|August 1, 1993
Summary
New biphasic shock sequences significantly lowered defibrillation thresholds (DFTs) in pigs. These findings suggest improved strategies for effective internal defibrillation using novel sequential and interleaved biphasic waveforms.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Low defibrillation thresholds (DFTs) are crucial for effective internal defibrillation.
- Sequential timing and biphasic shocks have previously shown promise in reducing DFTs.
Purpose of the Study:
- To evaluate the defibrillation efficacy of two novel shock sequences: interleaved biphasic and common phase sequential biphasic.
- To compare these new sequences against traditional monophasic and single biphasic waveforms.
Main Methods:
- Two-part study using anesthetized pigs (n=6 and n=9).
- Utilized a multi-electrode configuration including right ventricle, superior vena cava, LV apex, and thoracic patch.
- Measured defibrillation threshold energies for various biphasic and monophasic shock sequences.
Main Results:
- Interleaved biphasic and common phase sequential biphasic waveforms showed significantly lower DFTs compared to sequential monophasic and single biphasic waveforms (P < 0.0001).
- Phase reversal in common phase sequential biphasic shocks was critical, with biphasic shocks demonstrating much lower DFTs than monophasic counterparts (P < 0.0001).
- The efficacy of common phase sequential biphasics was comparable to sequential biphasics.
Conclusions:
- Novel interleaved biphasic and common phase sequential biphasic shock sequences are highly effective in reducing defibrillation thresholds.
- These findings support the potential of these advanced biphasic waveforms for improved internal defibrillation strategies.
- Possible mechanisms include enhanced myocardial shock exposure and optimized potential gradients during sequential phases.