Differential bipolar sensing of a dual chamber pacemaker

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Symptomatic heart block necessitates dual chamber pacing for optimal cardiac rhythm management.
• Unipolar (UP) sensing in pacemakers can be susceptible to extraneous electrical signals, potentially affecting pacing efficacy.
• Differential bipolar (DBP) sensing technology aims to improve signal discrimination and reduce sensing artifacts.

Purpose of the Study:

• To compare the efficacy of differential bipolar (DBP) sensing versus unipolar (UP) sensing in dual chamber pacemakers.
• To evaluate the incidence of myopotential sensing and far-field interference with both UP and DBP sensing modes.
• To assess the impact of external stimuli on ventricular pacing output under UP and DBP sensing conditions.

Main Methods:

• Electrograms were recorded from 10 heart block patients during pacemaker implantation using both UP and DBP amplifiers.
• Atrial and ventricular electrogram amplitudes were measured and compared between sensing modes.
• Isometric exercise tests and chest wall stimulation were performed to evaluate sensing performance and susceptibility to interference.

Main Results:

• DBP sensing demonstrated significantly higher peak-to-peak amplitudes for both atrial (4.2 mV vs 3.3 mV) and ventricular (7.5 mV vs 6.8 mV) electrograms compared to UP sensing.
• Myopotential sensing occurred in 90% of patients with UP sensing but in none with DBP sensing.
• Chest wall stimulation inhibited ventricular pacing in all patients with UP sensing, versus only 30% with DBP sensing at high outputs.

Conclusions:

• Differential bipolar (DBP) sensing is superior to unipolar (UP) sensing for dual chamber pacemakers.
• DBP sensing significantly reduces the risk of myopotential interference and far-field signal inhibition.
• The findings support the clinical utility of DBP sensing for improved pacemaker function and patient outcomes.