Which telemetry finding best identifies first-degree AV block?

Which telemetry finding best identifies first-degree AV block?

• A. Progressive PR prolongation with a dropped QRS
• B. Intermittent dropped QRS without PR prolongation
• C. Prolonged PR interval >0.20 s with all P waves conducted and followed by QRS
• D. Atria and ventricles beating independently with no fixed P-QRS relationship

Answer: (C)

First-degree AV block shows a consistently prolonged PR interval with all atrial impulses conducted to the ventricles. The conduction delay is in the AV node, so every P wave is followed by a QRS, but the interval from atrial to ventricular activation is longer than normal. On telemetry, this appears as a PR interval greater than 0.20 seconds that stays stable over time. Other patterns reflect different blocks: progressively lengthening PR with a dropped QRS is Mobitz type I, a dropped QRS without PR change is Mobitz type II, and complete AV dissociation shows no fixed P-to-QRS relationship. So, a prolonged yet constant PR interval with every P wave conducted best identifies first-degree AV block.

First-degree AV block shows a consistently prolonged PR interval with all atrial impulses conducted to the ventricles. The conduction delay is in the AV node, so every P wave is followed by a QRS, but the interval from atrial to ventricular activation is longer than normal. On telemetry, this appears as a PR interval greater than 0.20 seconds that stays stable over time. Other patterns reflect different blocks: progressively lengthening PR with a dropped QRS is Mobitz type I, a dropped QRS without PR change is Mobitz type II, and complete AV dissociation shows no fixed P-to-QRS relationship. So, a prolonged yet constant PR interval with every P wave conducted best identifies first-degree AV block.