What is the normal PR range?

• A. 140-240
• B. 120-200
• C. 100-180
• D. 80-120

Answer: (B)

The normal PR interval reflects the time from the start of atrial depolarization to the start of ventricular depolarization, essentially the conduction delay through the AV node and surrounding conduction pathway. On an ECG, this is measured from the beginning of the P wave to the beginning of the QRS complex. A normal value is about 0.12 to 0.20 seconds, or 120–200 milliseconds. That range is why the correct choice matches 120–200 ms.

If the PR interval is longer than 0.20 seconds, it indicates slowed AV nodal conduction (first-degree AV block). Shorter intervals (often near or below 0.12 seconds) are less typical and can occur with high heart rates or pre-excitation syndromes like Wolff-Parkinson-White, among other factors.