Which statement best describes the P wave and PR interval in first-degree AV block?

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Multiple Choice

Which statement best describes the P wave and PR interval in first-degree AV block?

First-degree AV block results from slowed conduction through the AV node, causing a prolonged PR interval while atrial depolarization and ventricular conduction remain otherwise normal. The hallmark is a PR interval longer than 0.20 seconds with every P wave followed by a QRS complex, and the P wave shape and QRS width staying normal. Therefore, the statement describing a normal P wave with a PR interval greater than 0.20 seconds best fits this block type. An inverted P wave would suggest atrial rhythm changes, an absent P wave points to a non-atrial source of rhythm, and a prolonged QRS would indicate a ventricular conduction delay such as a bundle branch block.

First-degree AV block results from slowed conduction through the AV node, causing a prolonged PR interval while atrial depolarization and ventricular conduction remain otherwise normal. The hallmark is a PR interval longer than 0.20 seconds with every P wave followed by a QRS complex, and the P wave shape and QRS width staying normal. Therefore, the statement describing a normal P wave with a PR interval greater than 0.20 seconds best fits this block type. An inverted P wave would suggest atrial rhythm changes, an absent P wave points to a non-atrial source of rhythm, and a prolonged QRS would indicate a ventricular conduction delay such as a bundle branch block.

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