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Related Experiment Video

Updated: Feb 9, 2026

Cardiac Response to β-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis
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Adrenergic effects on internal cardiac defibrillation threshold.

M F Rattes, A D Sharma, G J Klein

    The American Journal of Physiology
    |September 1, 1987
    PubMed
    Summary

    Autonomic neural tone impacts defibrillator effectiveness. This study found alpha- and beta-adrenoceptor agonists and antagonists did not significantly alter defibrillation thresholds in pigs using a sequential-pulse technique.

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    A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
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    A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation

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    Area of Science:

    • Cardiology
    • Autonomic Neuroscience
    • Pharmacology

    Background:

    • Autonomic neural tone influences cardiac arrhythmias.
    • Neural activity changes may affect implantable defibrillator efficacy by altering defibrillation thresholds.
    • Understanding these interactions is crucial for optimizing defibrillator therapy.

    Purpose of the Study:

    • To investigate the impact of alpha- and beta-adrenoceptor modulation on defibrillation energy requirements.
    • To determine if autonomic nervous system activity affects the defibrillation threshold.

    Main Methods:

    • Anesthetized pigs were used to assess defibrillation thresholds.
    • Sequential-pulse and single-pulse techniques were employed.
    • Alpha- and beta-adrenoceptor agonists (phenylephrine, isoproterenol) and antagonists (phentolamine, atenolol) were administered.

    Main Results:

    • Phenylephrine and isoproterenol did not significantly change defibrillation thresholds with the sequential-pulse method.
    • Phentolamine and atenolol also showed no significant effect on defibrillation thresholds.
    • Isoproterenol significantly decreased defibrillation threshold with the single-pulse method.

    Conclusions:

    • Autonomic adrenoceptor modulation does not consistently alter defibrillation thresholds with sequential-pulse stimulation.
    • The defibrillation method (sequential vs. single pulse) may influence the observed effects of autonomic agents.
    • Further research is needed to clarify the relationship between neural tone and defibrillation efficacy.