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Ventricular fibrillation-defibrillation in the toad Bufo paracnemis.
1Instituto Superior de Investigaciones Biológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Tucumán, Argentina.
International Journal of Cardiology
|April 1, 1988
Summary
This study found that South American toads could be repeatedly fibrillated and defibrillated, suggesting new mechanisms beyond traditional theories for cardiac arrhythmias.
Area of Science:
- Cardiology
- Comparative Physiology
- Electrophysiology
Background:
- Cardiac fibrillation is more common in highly differentiated animals.
- Lower species with uniform cardiac tissue rarely experience fibrillation.
Purpose of the Study:
- To investigate the mechanisms of cardiac fibrillation and defibrillation in the South American toad, Bufo paracnemis.
- To explore alternative mechanisms for cardiac arrhythmias beyond traditional theories.
Main Methods:
- Repeatedly induced fibrillation and defibrillation in two Bufo paracnemis specimens.
- Measured fibrillation threshold and defibrillation values using rectangular pulses.
- Observed spontaneous reversals during fibrillation-defibrillation episodes.
Main Results:
- A fibrillation threshold of approximately 3.8 mA/g was estimated.
- Defibrillation values ranged from 43 mA/g to 507 mA/g.
- Spontaneous reversals occurred before and after defibrillation shocks.
Conclusions:
- Current understanding of cardiac fibrillation mechanisms is limited.
- Reentry or multiple ectopic foci may not be the sole basic mechanisms.
- Deterministic chaos theory might explain cellular behavior leading to fibrillation.