Effects of internal defibrillation on an implanted pacing system with programmable polarity

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Managing cardiac arrhythmias often involves implantable cardioverter defibrillators (ICDs) and pacemakers.
• Ensuring pacemaker function after defibrillation shock is critical for patient safety.

Purpose of the Study:

• To evaluate the safety and compatibility of a programmable polarity pacemaker (RelayR 294-03) with an ICD system.
• To assess pacemaker performance following high-energy defibrillation shocks in a canine model.

Main Methods:

• Three RelayR 294-03 pacemakers were tested in dogs with leads in the right atrium and ventricle.
• Pacemakers were subjected to at least 24 high-energy biphasic and monophasic shocks from an ICD system.
• Intracardiac electrical potentials were measured during defibrillation using bipolar and unipolar configurations.

Main Results:

• No pacemaker system failures or mode switching (unipolar pacing/backup mode) were observed post-shock.
• Bipolar pacing configurations (tip-ring) resulted in significantly lower intracardiac potentials compared to unipolar configurations.
• Pacemakers consistently functioned within preshock specifications.

Conclusions:

• The programmable polarity pacemaker (RelayR 294-03) appears safe for use with ICD systems.
• Bipolar pacing configurations mitigate high electrical potentials during defibrillation.
• Further clinical testing is recommended before widespread adoption of combined ICD and pacemaker implantation.