On a standard ECG, the PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. Which of the following correctly describes the physiological events included within the PR interval?

• A Ventricular depolarization and early repolarization
• B Atrial repolarization only
• C AV nodal conduction only
• D Atrial depolarization, AV nodal conduction, and His-Purkinje conduction ✓

Explanation

The PR interval encompasses atrial depolarization (P wave), conduction delay through the AV node (the largest contributor to PR interval duration), and conduction through the bundle of bundle of His and Purkinje system to the onset of ventricular depolarization. Atrial repolarization occurs during the PR segment and is normally hidden within the PR interval. The QRS complex begins where the PR interval ends, representing ventricular depolarization.

Reference: Goldberger's Clinical Electrocardiography, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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