Examine the ECG rhythm below. The patient was being paced AAI . What is the problem with the pacing?

Image provided in examination paper

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College Answer

Oversensing. In this case myopotentials are sensed.

Discussion

The image above is from the below-referenced book on pacemaker physiology.

Its a mere diagram. These exotic rhythm disturbances are hard to find examples of.

Essentially, oversensing in AAI is the pacemaker mistaking some muscle potentials as atrial activity, and inhibiting itself. The result is a missed beat.

References

References

A good Google book on this subject is available for all to see:

Cardiac Pacing for the Clinician by Kusumoto and Goldschlager.