Advanced Cardiovascular Life Support (ACLS) Practice Exam

In which condition are there multiple P waves for every QRS complex, indicating block at the AV node?

1. Second degree AV block Mobitz Type 2

2. Sinus bradycardia

3. Third degree AV block

4. Atrial flutter

The correct answer is: Third degree AV block

In the scenario where there are multiple P waves for every QRS complex, indicating a block at the AV node, the correct condition is characterized by a complete dissociation between atrial and ventricular activity, which is known as third degree AV block (or complete heart block). In third degree AV block, the signals originating from the atria (P waves) and the ventricles (QRS complexes) are not coordinated. Consequently, the atria may generate P waves at a regular rate while the ventricles conduct independently at their own intrinsic rate. This phenomenon results in the presence of multiple P waves preceding each QRS complex, which is a hallmark of this level of block. The nature of this block leads to a much slower ventricular rhythm compared to the atrial rhythm, illustrating a complete block at the level of the AV node. Understanding this condition is crucial for recognizing severe conduction issues that may necessitate immediate intervention, such as pacing. The other conditions do not typically present with this clear dissociation between P waves and QRS complexes, making them less relevant in illustrating the specified situation of multiple P waves to QRS complexes indicative of block at the AV node.