Editing Pacemaker (section)

=== Sensing and sensitivity ===
An important aspect of pacemaker function is sensing the intrinsic heart activity. This is called sensing. Larger sensed voltages are desired and it is expected that the ventricle produces larger voltages than the atria.

The minimum voltage to sense an event is called the sensitivity. The higher the sensitivity, the less that is sensed, and vice-versa. Too low of a sensitivity can cause troubles with sensing P waves, T waves, and noise; sensing these things is called "over sensing". A sensitivity too high may result in missed sensing of P waves in the atria and QRS in the ventricles, and is called "under sensing."