Unipolar sensing in contemporary pacemakers: using myopotential testing to define optimal sensitivity settings
D V Exner1, J M Rothschild, S Heal
1Division of Cardiology, Foothills Hospital, Calgary, Alberta, Canada.
Summary
Contemporary unipolar leads show similar sensing to bipolar leads, but atrial unipolar leads are more prone to myopotential inhibition. Optimal programming reduces oversensing risks with unipolar leads.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Bipolar lead use is rising due to oversensing issues with older unipolar systems.
- Limited data exists on modern unipolar leads with improved design and flexibility.
Purpose of the Study:
- To compare sensing characteristics of contemporary unipolar and bipolar leads.
- To evaluate oversensing and myopotential inhibition in different lead polarities.
Main Methods:
- Randomized crossover study comparing unipolar and bipolar sensing in 34 patients.
- Intracardiac electrogram amplitudes, pacing/sensing thresholds, and provocative maneuvers were assessed.
- Optimal sensitivity settings were determined and validated with ambulatory ECG monitoring.
Main Results:
- Atrial unipolar leads showed significantly higher myopotential inhibition (50% vs. 5%) at higher sensitivities.
- Oversensing occurred in 6% of atrial and 8% of ventricular unipolar leads at optimal settings, versus none in bipolar leads.
- Undersensing was more frequent in atrial unipolar leads (29% vs. 6%).
Conclusions:
- Atrial unipolar leads can be prone to myopotential inhibition and oversensing, though optimal programming mitigates risks.
- Unipolar ventricular leads may be a viable option given concerns about bipolar lead longevity.
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