Death and damage caused by multiple direct current shocks: studies in an animal model

C M Wilson ¹, J D Allen , J B Bridges

⁰Regional Medical Cardiology Centre, Royal Victoria Hospital, Belfast, Northern Ireland.

European Heart Journal +

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November 1, 1988

View abstract on PubMed

Summary

Multiple high-energy defibrillator shocks increase mortality and cardiac damage in dogs. A single shock is well tolerated, but multiple shocks lead to pump failure, highlighting the need for optimized first-shock effectiveness.

Area Of Science

Cardiology
Veterinary Medicine
Electrophysiology

Background

Patients requiring multiple defibrillator shocks often have a poor prognosis.
The cardiac effects of multiple high-energy transthoracic shocks are not fully understood.
Acute mortality and cardiac damage following defibrillation require further investigation.

Purpose Of The Study

To evaluate the effects of single versus multiple high-energy transthoracic shocks on acute mortality and cardiac function in healthy greyhounds.
To assess myocardial damage and contractile failure following escalating doses of defibrillation.
To provide insights into patient outcomes after multiple defibrillator shocks.

Main Methods

Healthy greyhounds received one, five, or ten 400 J transthoracic shocks.
Acute mortality was recorded, with causes of death analyzed (asystole, electromechanical dissociation).
Myocardial tissue was examined via electron microscopy; cardiac damage was quantified macroscopically in survivors.

Main Results

Acute mortality significantly increased with the number of shocks administered (one shock: 0/6; five shocks: 8/18; ten shocks: 12/17).
Survivors receiving multiple shocks showed significant ST segment elevation and greater macroscopic cardiac damage compared to single-shock recipients.
Electron microscopy revealed few specific myocardial abnormalities despite significant contractile failure.

Conclusions

A single high-energy defibrillator shock is well tolerated in this greyhound model.
Multiple shocks cause significant cardiac injury, leading to acute pump failure and increased mortality.
These findings underscore the need to re-evaluate mortality causes in patients receiving multiple shocks and emphasize optimizing first-shock success.

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