Surgical open-chest ventricular defibrillation: triphasic waveforms are superior to biphasic waveforms

Area of Science:

• Cardiovascular Research
• Medical Device Technology
• Electrophysiology

Background:

• Endocardial defibrillation has been studied with triphasic shocks, but epicardial defibrillation has not.
• Open-chest epicardial defibrillation efficacy requires further investigation.

Purpose of the Study:

• To compare the efficacy and safety of biphasic versus triphasic shocks for open-chest epicardial defibrillation.
• To evaluate different electrode sizes in a porcine model.

Main Methods:

• Twenty-two pigs underwent electrically induced ventricular fibrillation (VF).
• Epicardial biphasic and triphasic shocks were delivered using large (44.2 cm2) and small (15.9 cm2) electrodes at varying energy levels (3-30 J).
• Success rates were determined by VF termination, and safety was assessed by induced arrhythmias.

Main Results:

• Triphasic shocks showed significantly higher success rates than biphasic shocks for VF termination across multiple energy levels, particularly with large electrodes.
• Both waveforms demonstrated similar rates of induced ventricular tachycardia and low incidence of asystole.
• Efficacy of triphasic shocks was demonstrated at energy levels from 3-20 J.

Conclusions:

• Triphasic waveform shocks are superior to biphasic waveform shocks for open-chest epicardial defibrillation in terminating VF.
• Triphasic shocks were found to be as safe as biphasic shocks in this porcine model.
• These findings support the potential of triphasic waveforms for improved epicardial defibrillation.