Patient Care Technician (PCT) AAH Practice Exam

What is indicative of a 2nd-degree block type known as Wenckebach?

1. Irregular heart rhythm with absent P waves

2. Progressive prolongation of PRI ending in a non-conducted P wave

3. Consistent PRI with varying QRS complexes

4. Spike before both P wave and QRS complex

The correct answer is: Progressive prolongation of PRI ending in a non-conducted P wave

The characteristic feature of a second-degree block known as Wenckebach, or Mobitz Type I, is the progressive prolongation of the PR interval (PRI) until a P wave fails to conduct to the QRS complex, resulting in a non-conducted P wave. This phenomenon occurs in a cyclical pattern where each successive P wave has a longer interval before the corresponding QRS, leading to this characteristic pattern. This progressive increase in PRI indicates that the conduction through the AV node is progressively becoming more impaired, which is a hallmark of Wenckebach. Once the PRI reaches a tipping point, a P wave is dropped, and the cycle then starts over again. This differs significantly from other arrhythmias, where the patterns of PRI and QRS complexes show different behaviors or regularities that are not indicative of the Wenckebach phenomenon. Understanding this mechanism can aid healthcare providers in recognizing the unique signs of this arrhythmia and determining appropriate management interventions.