Pacemaker undersensing is best described as?

Pacemaker undersensing is best described as?

• A. The device paces too fast
• B. The device fails to register depolarization
• C. The device detects noncardiac signals as pacing events
• D. The device shows normal function

Answer: (B)

Sensing the heart’s electrical activity accurately is essential for a pacemaker to coordinate pacing with the patient’s own rhythm. Undersensing means the device fails to detect a depolarization when it occurs. Because the pacemaker doesn’t recognize that the heart has already beat, it delivers a pacing stimulus as if the heart isn’t beating, which can lead to pacing inappropriately or out of sync with the intrinsic rhythm. This is different from pacing the heart too fast or from picking up noncardiac signals as pacing events (oversensing). If the device is not undersensing, it would be correctly detecting depolarizations and pacing only as needed.

Sensing the heart’s electrical activity accurately is essential for a pacemaker to coordinate pacing with the patient’s own rhythm. Undersensing means the device fails to detect a depolarization when it occurs. Because the pacemaker doesn’t recognize that the heart has already beat, it delivers a pacing stimulus as if the heart isn’t beating, which can lead to pacing inappropriately or out of sync with the intrinsic rhythm. This is different from pacing the heart too fast or from picking up noncardiac signals as pacing events (oversensing). If the device is not undersensing, it would be correctly detecting depolarizations and pacing only as needed.