Terminology - 317 - Pacemaker Rhythms.
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- Oversensing occurs when the device interprets non-cardiac sources of energy as being cardiac. This results in the device not turning on when it should.
- Undersensing results in a device that doesn’t know when to turn off. This may result in pacemaker competition, a potentially dangerous situation (as discussed earlier).
- Capture refers to when the device delivers an electrical impulse of sufficient strength to result in depolarization. The waveform immediately follows the pacing spike.
- Loss or Failure to Capture may occur for a number of reasons, but commonly occurs when the generator is unable to deliver a sufficient amount of energy to cause depolarization. This may be due to the age of the batteries. This will result in a spike with no corresponding depolarization or a delayed depolarization of unusual morphology.
Capture – notice the waveform immediately following the pacing spike.
Loss of Capture – notice the 4th and 7th complex morphology is different and the waveform does not immediately follow the pacing spike.
Authors and ReviewersAuthored by Thomas O'Brien
Medically reviewed by Dr. Jonathan Keroes, MD, Cardiology
Last Update: 11/8/2020