Prospective randomized comparison of biphasic waveform tilt using a unipolar defibrillation system

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• A unipolar defibrillation system using a single right ventricular (RV) electrode and implantable cardioverter defibrillator (ICD) shell demonstrates comparable efficacy to epicardial lead systems.
• Optimizing pulse waveform shape may further enhance unipolar defibrillation system performance.

Purpose of the Study:

• To investigate if reducing biphasic waveform tilt improves defibrillation efficacy in a unipolar transvenous system.
• To compare the defibrillation threshold (DFT) using 50% and 65% tilt asymmetric biphasic waveforms.

Main Methods:

• Prospective, randomized comparison of 50% and 65% tilt biphasic waveforms in 15 cardiac arrest survivors.
• Utilized a unipolar system with an RV electrode (anode) and ICD shell (cathode).
• Measured defibrillation threshold (DFT) parameters including stored energy, delivered energy, voltage, current, resistance, and pulse width.

Main Results:

• The 65% tilt biphasic pulse yielded a stored energy DFT of 8.7 ± 5.7 J and delivered energy DFT of 7.6 ± 5.0 J.
• The 50% tilt biphasic pulse resulted in a stored energy DFT of 8.2 ± 5.4 J and delivered energy DFT of 6.1 ± 4.0 J.
• All patients in both groups achieved DFTs < 20 J, with no statistically significant difference between the two tilt angles (P = 0.69 and 0.17).

Conclusions:

• The unipolar single-lead transvenous defibrillation system achieves defibrillation at energy levels comparable to epicardial systems.
• Reducing biphasic waveform tilt to 50% does not enhance defibrillation efficacy compared to the standard 65% tilt.