Low-energy endocardial defibrillation using dual, triple, and quadruple electrode systems

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Implantable cardioverter-defibrillators (ICDs) are crucial for managing life-threatening arrhythmias.
• Optimizing lead systems and defibrillation energy is key for less invasive ICDs.
• Nonthoracotomy lead systems and low-energy shocks improve patient outcomes and device longevity.

Purpose of the Study:

• To assess the feasibility of universal nonthoracotomy leads and low defibrillation energy (< or = 15 J).
• To optimize lead system configurations for low-output biphasic shock pulse generators (<30 J).
• To determine effective electrode configurations for successful defibrillation in patients with ventricular arrhythmias.

Main Methods:

• Sixteen patients with ventricular tachycardia or fibrillation underwent defibrillation threshold testing in two stages.
• Stage 1: Right ventricle (RV) to superior vena cava (SVC) and axillary patch configurations.
• Stage 2: RV to pectoral can and RV to an "array" (SVC, can, axillary patch) configuration.

Main Results:

• RV to axillary patch (12.7 J) and RV to SVC + axillary patch (9.8 J) showed lower thresholds than RV to SVC (14.2 J).
• RV to array (5.6 J) had the lowest threshold; RV to pectoral can (9.2 J) was the best dual-electrode system.
• Low-energy endocardial defibrillation (< or =10 J) was feasible in 72% of patients with multiple electrode configurations at 10 J.

Conclusions:

• Reducing maximum pulse generator output to < or =25 J with these configurations is feasible.
• Optimized lead systems allow for effective low-energy defibrillation, enhancing safety margins.
• Nonthoracotomy lead systems combined with low-energy biphasic shocks are viable for ICDs.