AEMCA Practice Exam

What does Mobitz Type 1 signify regarding the AV node?

1. The AV node is fully functional

2. The AV node is completely blocked

3. The AV node is partially blocked, causing a dropped beat

4. The AV node conducts impulses without delay

The correct answer is: The AV node is partially blocked, causing a dropped beat

Mobitz Type 1, also known as Wenckebach, signifies a partial block in the conduction system at the level of the AV node. In this scenario, there is a progressive delay in the conduction of impulses from the atria to the ventricles until one impulse is completely blocked and not conducted to the ventricles, resulting in a dropped beat. This characteristic pattern typically manifests as a gradual lengthening of the PR interval, which is followed by a failure to conduct a heartbeat. Recognizing that Mobitz Type 1 indicates some level of dysfunction in the AV node, it is important to distinguish that while the node is not fully blocked, its ability to conduct impulses is compromised. This partial block leads to the observable variability in the heart's rhythm, typical of this phenomenon. In contrast, fully functional AV conduction would not exhibit dropped beats, and a complete block would result in a more severe disruption of the signal transmission, causing a different clinical presentation. Thus, Mobitz Type 1 is specifically indicative of this partial block and the resultant arrhythmia.