Discrimination of antegrade and retrograde atrial depolarization by electrogram analysis

Area of Science:

• Biomedical Engineering
• Cardiology
• Electrophysiology

Background:

• Dual-chamber pacemakers and antitachycardia devices face limitations due to the inability to selectively reject retrograde P waves.
• This limitation can lead to endless loop tachycardias and compromise sensing algorithms in antitachycardia devices.

Purpose of the Study:

• To determine selective sensing parameters for differentiating antegrade and retrograde atrial electrograms.
• To assess the feasibility of rejecting retrograde P waves while sensing antegrade P waves using current pacemaker technology.

Main Methods:

• Measured amplitude, slew rate, and configuration of antegrade and retrograde atrial electrograms in 34 patients undergoing dual-chamber pacemaker implantation.
• Analyzed differences between antegrade and retrograde electrograms in unipolar and bipolar pacemaker systems.

Main Results:

• All 34 cases showed measurable differences in antegrade and retrograde atrial electrogram amplitudes.
• Significant differences in slew rate were observed in most cases, and configuration varied.
• A combined criterion using amplitude (0.25 mV steps) and slew rate (0.5 V/sec gradations) could discriminate retrograde from antegrade depolarizations in all patients.

Conclusions:

• Amplitude and slew rate differences in atrial electrograms are sufficient to distinguish antegrade from retrograde P waves.
• Current pacemaker technology, utilizing amplitude and slew rate discrimination, can effectively reject retrograde P waves, improving dual-chamber pacemaker and antitachycardia device performance.