Third-degree AV block has
A)one P wave to each QRS.
B)a varying R-R interval.
C)a constant PR interval.
D)a varying PR interval.

Question

Quizplus · Accepted Answer

Third-degree AV block, also known as complete heart block, occurs when there is no conduction of impulses from the atria to the ventricles. As a result, the P waves and QRS complexes are dissociated, meaning they are not related to each other. Therefore, the PR interval, which represents the time from the onset of the P wave to the onset of the QRS complex, is variable in third-degree AV block. The correct answer is D, a varying PR interval.

Third-Degree AV Block Has