New approach to biphasic waveforms for internal defibrillation: fully discharging capacitors.

Area of Science:

• Biomedical Engineering
• Cardiovascular Devices
• Electrical Engineering

Background:

• Biphasic defibrillation waveforms utilize two capacitors per phase, potentially simplifying internal defibrillator design.
• Investigating optimal capacitor combinations is crucial for developing smaller, more efficient internal defibrillators.

Purpose of the Study:

• To determine the ideal capacitor sizes for a two-capacitor, full-discharge biphasic waveform.
• To compare the efficacy of various two-capacitor waveforms against a standard single-capacitor waveform.

Main Methods:

• Eight distinct full-discharge biphasic waveforms were generated using varying phase-1 (30-90 microF) and phase-2 (1/3 to 1.0 times phase-1) capacitors.
• Waveform efficacy was assessed in a porcine ventricular fibrillation model (n=12) using energy (E50) and voltage (V50) at 50% success.
• Comparisons were made against a single-capacitor (120 microF) waveform.

Main Results:

• Full-discharge waveforms with phase-2 capacitors ≤40 microF showed comparable E50 to the single-capacitor waveform.
• Waveforms with phase-2 capacitors ≥60 microF exhibited significantly higher E50 (P < 0.05).
• Efficient waveforms (phase-2 ≤40 microF) with phase-1 capacitors ≥60 microF demonstrated V50 values similar to the single-capacitor waveform.

Conclusions:

• Selecting appropriate capacitor values is essential for maintaining defibrillation efficacy with a two-capacitor, full-discharge waveform.
• This research provides a basis for designing simplified and miniaturized internal defibrillators.