Patient Care Technician (PCT) AAH Practice Exam

Wenckebach is characterized by increasingly prolonged PRI followed by what?

1. A QRS complex

2. A P wave

3. An irregular heartbeat

4. A compensatory pause

The correct answer is: A P wave

Wenckebach, or Mobitz Type I second-degree AV block, is characterized by a progressive lengthening of the PR interval until a beat is dropped. This phenomenon leads to the absence of a QRS complex following a P wave after the PR interval reaches a certain threshold. The key feature is that after the dropped beat, the cycle repeats itself, with the subsequent P wave appearing after a longer PR interval before another QRS is produced. This creates a "grouped beating" pattern. The correct answer emphasizes that after the prolonged PRI, the rhythm continues with a P wave that is not followed by a QRS complex. This repetition of P waves without QRS complexes is what delineates Wenckebach from other types of blocks. Thus, recognizing that the block leads to a dropped QRS due to the AV node's inability to conduct the impulse, followed by another P wave, is essential in identifying the characteristics of this arrhythmia. While an irregular heartbeat might occur in conjunction with the arrhythmia due to the dropped QRS complexes, it does not specifically follow the pattern or the hallmark description inherent to Wenckebach. Furthermore, QRS complexes themselves do not follow the P wave in this scenario due to the