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Transmyocardial impedance during single and multiple internal ventricular defibrillation shocks
W Peters1, S Solingen, Y Kobayashi
1Medizinische Klinik, Universität Würzburg, Germany.
The American Journal of Physiology
|August 1, 1994
Summary
Transmyocardial impedance during internal ventricular defibrillation is mainly resistive and decreases with repeated shocks. This impedance is voltage-dependent but does not affect defibrillation success.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Transmyocardial impedance during internal ventricular defibrillation is not well understood.
- Understanding impedance is crucial for optimizing defibrillation protocols.
Purpose of the Study:
- To investigate the characteristics of transmyocardial impedance during internal ventricular defibrillation.
- To determine the relationship between voltage, current, impedance, delivered energy, and defibrillation success.
Main Methods:
- Utilized a canine model with high-rate on-line digitization and random shock delivery.
- Employed titanium electrodes to measure electrical parameters during defibrillation shocks.
- Analyzed impedance changes within individual and successive defibrillation shocks.
Main Results:
- Transmyocardial impedance decreased with repeated defibrillation in most dogs (10/11).
- Impedance increased during trapezoidal discharges, while voltage decreased.
- Lower impedance was observed with high energy-voltage shocks.
- Polarization voltage was consistently detected, indicating a primarily resistive impedance.
Conclusions:
- Transmyocardial impedance during defibrillation is primarily resistive, nonlinear, and voltage-dependent.
- Impedance declines with successive shocks but does not influence defibrillation success.
- Findings contribute to a better understanding of electrical properties during cardiac defibrillation.