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October 1, 1988AJP Heart and Circulatory Physiology

Epicardial activation after unsuccessful defibrillation shocks in dogs

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Why the study?

How do different defibrillation shock energies affect epicardial activation patterns during electrically induced fibrillation in dogs?

Population

7 dogs with electrically induced fibrillation

Comparison

Defibrillation shocks of varying energies… vs Different shock energies

Design

Preclinical

Authors

NSNitaro ShibataPCP. S. ChenEDE G Dixon

Discussion

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Overview

Shock energies <10 J fail to defibrillate or reinduce VF at the base in dogs; leaves open optimal thresholds and sites for human device design.

Key Points

  • To investigate the effects of varying shock strengths during defibrillation on epicardial activation in dogs.
  • Conducted defibrillation experiments using seven dogs with 56 epicardial electrodes recorded during induced fibrillation.
  • Administered shocks of varying intensities (0.01-5 J) to evaluate activation at different heart sites.
  • Analyzed the relationship between shock strength and the timing and location of activation sites.
  • For 0.01-0.05 J shocks, activation occurred shortly after the shock across multiple sites.
  • At 0.1-0.5 J, fewer early activation sites were recorded, with increased latency at the apex.
  • Only 1-3 early activation sites appeared at the base with delays for shocks of 1-5 J.

Structured PICO

How do different defibrillation shock energies affect epicardial activation patterns during electrically induced fibrillation in dogs?

P
Population
7 dogs with electrically induced fibrillation
I
Intervention
Defibrillation shocks of varying energies (0.01 to 10 J) delivered via electrodes on the left ventricular apex and right atrium
C
Comparator
Different shock energies (0.01-0.05 J, 0.1-0.5 J, 1-5 J, 10 J)
O
Outcome
Epicardial activation patterns (latency and location of earliest activation) recorded from 56 epicardial electrodessurrogate

The study demonstrates that successful defibrillation requires a shock strong enough to halt fibrillation without reinitiating it, highlighting three distinct effects of varying shock field intensities.

Cite This Study

Shibata et al. (1988) studied this question.

synapsesocial.com/papers/6a75fca774b63c188eb20c85https://doi.org/10.1152/ajpheart.1988.255.4.h902
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Also Consider

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

  1. 1Comparison of activation during ventricular fibrillation and following unsuccessful defibrillation shocks in open-chest dogs.1990 · 117 citations
  2. 2Epicardial mapping of ventricular defibrillation with monophasic and biphasic shocks in dogs.1993 · 164 citations
  3. 3Mechanism of cardiac defibrillation in open-chest dogs with unipolar DC-coupled simultaneous activation and shock potential recordings.1990 · 148 citations
  4. 4Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.1987 · 211 citations
  5. 5Prediction of Defibrillation Outcome by Epicardial Activation Patterns Following Shocks Near the Defibrillation Threshold2000 · 40 citations