Cardiac Medicine Certification Practice Exam 2025 – Comprehensive Prep Guide

Question: 1 / 400

In 2nd degree AV block Type I (Wenckebach), how is the PR interval affected?

It remains constant throughout the rhythm.

It gradually lengthens before a dropped QRS complex.

In 2nd degree AV block Type I, also known as Wenckebach, the defining characteristic is that the PR interval progressively lengthens with each successive heartbeat until a QRS complex is finally dropped. This phenomenon is referred to as "grouped beating" or "progressive block."

The gradual elongation of the PR interval is a reflection of the increasing delay in conduction through the AV node. As the cycle continues, this progressive lengthening continues until the electrical impulse fails to transmit, leading to a missed or dropped QRS complex. Following this, the cycle resets, and the pattern repeats.

This pattern of progressively increasing intervals followed by a dropped beat is what differentiates Wenckebach from other types of AV block, making it crucial to recognize the specific behavior of the PR interval in this scenario.

Get further explanation with Examzify DeepDiveBeta

It is shorter than 0.12 seconds.

It is consistently longer than 0.20 seconds.

Next Question

Report this question

Download Cardiac Medicine Certification (CMC) Practice Exam PDF Study Guide
Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy