How would you recognize a second-degree AV block type I (Wenckebach)?

In recognizing a second-degree AV block type I, commonly referred to as Wenckebach, the key characteristic to observe is the progressive lengthening of the PR interval leading up to a dropped QRS complex. This pattern arises from the gradual slowing of conduction through the AV node until the impulse is eventually blocked and does not result in a QRS complex. This unique feature distinguishes Wenckebach from other types of AV blocks, as the pattern is quite specific: after a certain number of beats, typically two to four, the QRS complex will be dropped.

This consistent pattern of the PR interval lengthening followed by a loss of QRS ultimately helps identify the Wenckebach phenomenon, making it vital for monitor technicians to recognize and differentiate it from other arrhythmias where PR intervals may remain constant or vary unpredictably.