Right atrial septal electrode for reducing the atrial defibrillation threshold

Area of Science:

• Cardiovascular Electrophysiology
• Medical Device Technology

Background:

• The standard right atrial appendage (RAA) to coronary sinus (CS) lead configuration for atrial defibrillation has a high energy threshold.
• Previous studies indicated a >50% reduction in atrial defibrillation threshold (ADFT) with a trans-septal electrode.

Purpose of the Study:

• To evaluate if a more clinically practical electrode placement in the right atrium along the atrial septum (RSP) could lower the ADFT.
• Investigate the efficacy of a novel electrode configuration for atrial defibrillation.

Main Methods:

• Sustained atrial fibrillation was induced in sheep using burst pacing and pharmacological agents.
• A custom dual-defibrillation catheter with electrodes in the lateral right atrium (RA), CS, and RSP was used.
• ADFT was assessed for various lead configurations, including RAA-->CS and sequential shocks involving RSP, using biphasic waveforms.

Main Results:

• The sequential-shock configuration CS-->RSP/RA-->RSP significantly lowered delivered energy (0.53+/-0.31 J), peak voltage (86+/-22 V), and peak current (1.6+/-0.6 A) compared to RAA-->CS (1.14+/-0.64 J, 157+/-34 V, 2.5+/-1.1 A).
• No significant difference was found between RAA-->CS and RA-->CS configurations.
• Similar ADFT characteristics were observed for CS-->RSP/RA-->RSP and CS-->RSP/RAA-->RSP configurations.

Conclusions:

• An additional electrode placed at the RSP can markedly reduce the ADFT of the standard RAA-->CS configuration.
• This RSP electrode configuration offers a potentially more effective and lower-energy approach to atrial defibrillation.