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September 1, 1997Pacing and Clinical Electrophysiology

Biphasic Waveforms for Ventricular Defibrillation: Optimization of Total Pulse and Second Phase Durations

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Key result

Biphasic waveforms with total durations of 4 ms required higher defibrillation voltage than 8-ms control waveforms (174 vs 127 V; P=0.001) in an isolated rabbit heart model.

Why the study?

Do specific biphasic waveform parameters (total and second phase duration) reduce voltage and energy requirements for ventricular defibrillation in an isolated rabbit heart model?

Population

Isolated rabbit heart model using the Langendorff technique (n=70 experiments)

Comparison

Biphasic waveforms with varying total durations… vs Symmetric biphasic control waveform of 8 ms and…

Design

Preclinical

Authors

MMMARKUS H. MATULAVanderbilt UniversityMBMichael J. BrooksAfrica Health Research InstituteQPQi PanGeorge Washington University Hospital

Discussion

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Implication

Shorter biphasic waveforms increase defibrillation voltage needs; leaves open optimal durations for clinical translation.

Key Points

  • To evaluate the effects of total pulse duration and second-phase duration on voltage and energy requirements for biphasic ventricular defibrillation.
  • Evaluated defibrillation efficacy in isolated rabbit hearts using the Langendorff technique with truncated exponential waveforms to determine 50% success thresholds (E50).
  • Compared symmetric biphasic waveforms of 4, 6, and 16 ms total duration to an 8-ms control waveform across 30 experiments.
  • Tested a monophasic waveform (4 ms) and asymmetric biphasic waveforms (4+2, 4+8, and 4+16 ms) against a 4+4 ms symmetric control waveform across 40 experiments.
  • Symmetric 4-ms waveforms required higher defibrillation voltage (174 ± 56 V) than the 8-ms control (127 ± 49 V; P = 0.001), while 6-ms and 16-ms waveforms showed no significant differences.
  • Monophasic waveforms required significantly higher energy (2.15 ± 1.21 J vs. 1.24 ± 0.41 J; P ≤ 0.05) and voltage (223 ± 64 V vs. 160 ± 26 V; P = 0.02) compared to the 4+4 ms control.
  • The 4+16 ms waveform required higher energy (1.86 ± 1.09 J vs. 0.87 ± 0.7 J; P ≤ 0.05) than control, whereas 4+2 ms and 4+8 ms waveforms maintained similar energy and voltage requirements.

Structured PICO

Do specific biphasic waveform parameters (total and second phase duration) reduce voltage and energy requirements for ventricular defibrillation in an isolated rabbit heart model?

P
Population
70 experiments in an isolated rabbit heart model evaluating the effects of total pulse duration and second phase duration on defibrillation efficacy.
I
Intervention
Biphasic waveforms with varying total durations (4 ms, 6 ms, 16 ms) and asymmetric second phase durations (4+2 ms, 4+8 ms, 4+16 ms)
C
Comparator
Symmetric biphasic control waveform of 8 ms (4+4 ms) and monophasic waveform (4+0 ms)
O
Outcome
50% probability-of-success levels (E50) for delivered energy and initial voltage for defibrillationsurrogate

Main Result

Absolute Event Rate: 174% vs 127%

p-value: p=0.001

Biphasic waveforms with total durations between 6-16 ms and second phase durations ranging from 50%-200% of the first phase optimize defibrillation efficacy in an isolated rabbit heart model.

Cite This Study

MATULA et al. (1997) studied Ventricular fibrillation (n=70). Biphasic waveforms with varying total and second phase durations vs. 8 ms (4 + 4 ms) symmetric biphasic waveform was evaluated on Defibrillation voltage requirements (p=0.001). Biphasic waveforms with total durations of 4 ms required higher defibrillation voltage than 8-ms control waveforms (174 vs 127 V; P=0.001) in an isolated rabbit heart model.

synapsesocial.com/papers/6aa70a89b933c48d8a827fe6https://doi.org/10.1111/j.1540-8159.1997.tb04231.x

Topics

Cardiac device therapy
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Strength‐Duration Curves of Fixed Pulse Width Variable Tilt Truncated Exponential Waveforms for Nonthoracomy Internal Defibrillation in Dogs1988 · 45 citations
  2. 2Strength-Duration Curves for Ventricular Defibrillation in Dogs1970 · 39 citations
  3. 3Epicardial and Nonthoracotomy Defibrillation Lead Systems Combined with a Cardioverter Defibrillator1995 · 14 citations
  4. 4Optimization of biphasic waveforms for human nonthoracotomy defibrillation.1993 · 86 citations
  5. 5Effect of Biphasic Waveform Pulse on Endocardial Defibrillation Efficacy in Humans1994 · 42 citations