Question

During a Mobitz Type I second-degree AV block, what pattern describes the behavior of the PR interval before a QRS complex is dropped?

Accepted Answer

In a Mobitz Type I second-degree AV block, also known as Wenckebach phenomenon, the PR interval progressively lengthens with each consecutive beat until a QRS complex is dropped. The PR interval is the time measurement from the start of the P wave, which represents atrial contraction, to the beginning of the QRS complex, which represents ventricular contraction. As the signal travels from the atria to the ventricles, the AV node experiences a delay that increases incrementally with every heartbeat. This progressive delay continues until the electrical impulse from the atria is completely blocked and fails to reach the ventricles, resulting in a P wave that is not followed by a QRS complex. After this dropped beat, the conduction system resets, and the pattern begins again with a shorter PR interval on the next conducted beat.

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During a Mobitz Type I second-degree AV block, what pattern describes the behavior of the PR interval before a QRS complex is dropped?

In a Mobitz Type I second-degree AV block, also known as Wenckebach phenomenon, the PR interval progressively lengthens with each consecutive beat until a QRS complex is dropped. The PR interval is the time measurement from the start of the P wave, wh....