What is the clinical evidence from this study?

Population: Ventricular fibrillation (n=6). Intervention: Monophasic truncated exponential 10-msec defibrillation shocks. Primary outcome: Mechanism of successful vs unsuccessful defibrillation (annihilation of fibrillating activity).

What question did this study set out to answer?

This study aims to understand the mechanisms of cardiac defibrillation and the importance of critical mass for successful outcomes.

July 1, 1990CirculationOpen Access

Mechanism of cardiac defibrillation in open-chest dogs with unipolar DC-coupled simultaneous activation and shock potential recordings.

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Key result

Successful defibrillation requires affecting a critical mass of myocardium (which can be <100%), whereas unsuccessful defibrillation is always accompanied by residual fibrillating activity.

Key Points

This study aims to understand the mechanisms of cardiac defibrillation and the importance of critical mass for successful outcomes.
Conducted 203 defibrillation attempts in six open-chest dogs with electrically induced ventricular fibrillation.
Used unipolar electrodes at 120 sites to measure voltage gradients and myocardial activity before and after shocks.
Applied shocks of varying energy levels (0.5-35 J) through specific atrial and ventricular electrode placements.
139 attempts were successful, while 64 were unsuccessful; all unsuccessful cases showed residual fibrillation.
Successful defibrillation resulted in either complete annihilation of fibrillating activity or near-complete cessation with one area of persistent fibrillation.
The latter type of successful defibrillation often involved dynamic encapsulation with refractory tissue affecting critical mass.

Structured PICO

Population

6 open-chest dogs undergoing 203 defibrillation attempts during electrically induced ventricular fibrillation.

Intervention

Monophasic truncated exponential 10-msec defibrillation shocks (0.5-35 J) delivered through an anodal patch on the right atrium and a cathodal patch on the left ventricular apex (203 defibrillation attempts)

Outcome

Myocardial electrical activity and voltage gradient before and immediately after the shock to determine annihilation of fibrillating activitysurrogate

Successful defibrillation requires affecting a critical mass of myocardium (which can be less than 100%), whereas unsuccessful defibrillation is always accompanied by residual fibrillating activity.

Discussion

No takes yet. Share an insight, caveat, or question.

Implication

Critical mass annihilation required for defibrillation success; leaves open refinement of modern ICD therapies.

Cite This Study

Witkowski et al. (1990) studied Ventricular fibrillation (n=6). Monophasic truncated exponential 10-msec defibrillation shocks was evaluated on Mechanism of successful vs unsuccessful defibrillation (annihilation of fibrillating activity). Successful defibrillation requires affecting a critical mass of myocardium (which can be <100%), whereas unsuccessful defibrillation is always accompanied by residual fibrillating activity.

synapsesocial.com/papers/6a445bf87b6aca5f195a2979 https://doi.org/10.1161/01.cir.82.1.244

View Full Paper

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Mechanism of cardiac defibrillation in open-chest dogs with unipolar DC-coupled simultaneous activation and shock potential recordings.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Mechanism of cardiac defibrillation in open-chest dogs with unipolar DC-coupled simultaneous activation and shock potential recordings.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider