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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.
Abstract:
A patient with congenital complete heart block underwent implantation of a dual-chamber pacemaker. He presented to the emergency room with fatigue and was found to be in atrial flutter. Device interrogation revealed undersensing of 5 mV flutter waves at a programmed sensitivity of 0.5 mV. Due to undersensing, mode switch did not occur. This case illustrates apparently paradoxical undersensing of atrial flutter waves by a dual-chamber pacemaker and can be explained by a phenomenon known as "quiet timer blanking."
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