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Paradoxical undersensing during atrial flutter: what is the mechanism?
Gautham Kalahasty1, David N Kenigsberg, Mark A Wood
1From the Virginia Commonwealth University Medical Center, Richmond, VA 23298-0053, USA.
Journal of Cardiovascular Electrophysiology
|August 2, 2006
Summary
Dual-chamber pacemakers may fail to detect atrial flutter due to "quiet timer blanking," leading to improper device function. This case highlights a paradoxical undersensing issue in pacemaker patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Congenital complete heart block necessitates pacemaker implantation for rate control.
- Dual-chamber pacemakers are designed to sense atrial and ventricular activity for synchronized pacing.
Observation:
- A patient with congenital complete heart block presented with fatigue and atrial flutter.
- Device interrogation revealed undersensing of atrial flutter waves (5 mV) despite programmed sensitivity (0.5 mV).
Findings:
- The pacemaker failed to sense the atrial flutter, preventing automatic mode switching.
- This paradoxical undersensing is attributed to the 'quiet timer blanking' phenomenon.
Implications:
- Highlights a potential failure mode in dual-chamber pacemakers during atrial flutter.
- Underscores the importance of understanding 'quiet timer blanking' for accurate pacemaker programming and patient management.
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