A second defibrillator chest patch electrode will increase implantation rates for nonthoracotomy defibrillators

Area of Science:

• Cardiology
• Medical Devices
• Electrophysiology

Background:

• Nonthoracotomy defibrillator systems offer lower morbidity and mortality than epicardial systems.
• Implantation failure rates for nonthoracotomy systems can reach up to 15%, particularly with monophasic waveforms.
• Elevated defibrillation thresholds pose a significant challenge to successful nonthoracotomy defibrillator implantation.

Purpose of the Study:

• To prospectively evaluate the effectiveness of incorporating a second chest patch electrode in nonthoracotomy defibrillator systems.
• To determine if an additional electrode can overcome high defibrillation thresholds and improve implantation success rates.

Main Methods:

• Fourteen patients with elevated defibrillation thresholds (≥ 24 J) were studied.
• An initial system with a right ventricular electrode and a single subscapular chest patch electrode was used.
• A second chest patch electrode was added (anterior subcutaneous or subscapular submuscular) if the initial threshold was high.

Main Results:

• The addition of a second chest patch electrode reduced system impedance from 72.3 ± 13.3 Ω to 52.2 ± 8.6 Ω.
• Defibrillation thresholds decreased significantly from ≥ 24 J to 16.6 ± 2.8 J with the two-patch system.
• All fourteen patients achieved successful implantation of the nonthoracotomy defibrillator system.

Conclusions:

• A second chest patch electrode, particularly with a subscapular placement, effectively lowers defibrillation thresholds.
• This strategy significantly increases implantation success rates for nonthoracotomy defibrillator systems in challenging cases.
• The findings support the use of an additional chest patch electrode to optimize nonthoracotomy defibrillator system performance.