Triphasic waveforms are superior to biphasic waveforms for transthoracic defibrillation: experimental studies

Area of Science:

• Cardiovascular Research
• Electrophysiology
• Medical Device Technology

Background:

• Previous studies in chick embryos suggested triphasic shocks cause less post-shock dysfunction compared to biphasic shocks.
• Understanding waveform efficacy is crucial for optimizing defibrillation protocols.

Purpose of the Study:

• To evaluate the effectiveness of triphasic waveforms versus biphasic waveforms for transthoracic defibrillation.
• To compare outcomes in a swine model of induced ventricular fibrillation (VF).

Main Methods:

• Swine models (n=59) underwent electrically induced ventricular fibrillation (VF).
• Transthoracic shocks using biphasic and triphasic waveforms were delivered at various energy levels (50-300 J) and pulse durations.
• Waveform efficacy was assessed by successful VF termination and occurrence of post-shock arrhythmias like ventricular tachycardia (VT) and asystole.

Main Results:

• Triphasic shocks with equal pulse durations demonstrated significantly higher success rates in terminating VF at low delivered energies (<65 J) compared to biphasic shocks.
• Waveforms with equal energy but varying pulse durations showed poorer success rates for both biphasic and triphasic configurations.
• Fewer instances of shock-induced ventricular tachycardia (VT) and asystole were observed following triphasic shock delivery.

Conclusions:

• Triphasic transthoracic shocks, when utilizing equal pulse durations, are superior to biphasic shocks for terminating VF, particularly at lower energy levels.
• The triphasic waveform with equal pulse durations also appears to reduce the incidence of adverse post-shock events, including VT and asystole.