A sinus rhythm with a consistently prolonged PR interval and all P waves followed by QRS represents which condition?

• A. First-degree AV block
• B. Normal sinus rhythm
• C. Second-degree AV block Type I
• D. Third-degree AV block

Answer: (A)

This pattern reflects a conduction delay in the AV node where atrial impulses still reach the ventricles, but the transmission is slower than normal. The hallmark is a PR interval that remains consistently prolonged (typically longer than 0.20 seconds) while every P wave is followed by a QRS. In other words, there is no dropped QRS, just a longer atrioventricular conduction time.

Normal sinus rhythm would have a normal PR interval. In second-degree AV block Type I, you would see progressive PR prolongation with intermittent dropped QRS complexes. In third-degree AV block, there is complete AV dissociation with no fixed relationship between P waves and QRS complexes.