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Increased defibrillation threshold due to ventricular fibrillation duration. Potential mechanisms
1Department of Medicine, New York Hospital-Cornell University Medical Center, NY 10021, USA.
Journal of Electrocardiology
|January 1, 1995
Summary
Myocardial adenosine release during ventricular fibrillation (VF) significantly increases defibrillation threshold (DFT). This adenosine-mediated effect likely explains why longer VF durations reduce defibrillation success rates.
Area of Science:
- Cardiology
- Physiology
- Pharmacology
Background:
- Ventricular fibrillation (VF) duration is a critical factor influencing defibrillation success.
- Metabolic acidosis or alkalosis do not impact defibrillation outcomes.
- Adenosine release during VF may mediate time-dependent effects on defibrillation.
Purpose of the Study:
- To investigate the hypothesis that myocardial adenosine release mediates the time-dependent increase in defibrillation threshold (DFT) during VF.
- To determine the effect of adenosine on DFT in a canine model.
- To explore the mechanism of adenosine's effect on DFT.
Main Methods:
- Determined transthoracic and transmyocardial DFT in dogs.
- Administered adenosine and dipyridamole (a nucleoside transport blocker) concurrently.
- Assessed the impact of autonomic denervation on adenosine's effects on DFT.
Main Results:
- Transthoracic DFT increased by approximately 50% with adenosine infusion.
- Transmyocardial DFT increased by approximately 100% with adenosine infusion.
- Adenosine's detrimental effects on DFT were abolished in autonomically denervated dogs, indicating an antiadrenergic mechanism.
Conclusions:
- Myocardial adenosine release during VF significantly increases DFT.
- Adenosine likely plays a key role in the time-dependent increase of DFT observed with prolonged VF duration.
- The antiadrenergic actions of adenosine contribute to its negative impact on defibrillation efficacy.