Normal PR interval falls within which time range?

Normal PR interval falls within which time range?

• A. 0.10-0.15
• B. 0.20-0.30
• C. 0.12-0.20
• D. 0.04-0.12

Answer: (C)

The PR interval shows the time it takes for the electrical impulse to travel from the atria through the AV node to the ventricles, from the start of the P wave to the start of the QRS complex. In a healthy heart, this conduction time is about 0.12 to 0.20 seconds (120–200 milliseconds). This range represents normal AV nodal conduction with enough delay to allow proper atrial contraction and ventricular filling without being too fast or too slow. Therefore, 0.12–0.20 seconds is the standard normal interval. If the interval is shorter, it can occur with atypical fast conduction or accessory pathways; if it’s longer than 0.20 seconds, it suggests some degree of AV nodal delay, such as first-degree AV block.

The PR interval shows the time it takes for the electrical impulse to travel from the atria through the AV node to the ventricles, from the start of the P wave to the start of the QRS complex. In a healthy heart, this conduction time is about 0.12 to 0.20 seconds (120–200 milliseconds). This range represents normal AV nodal conduction with enough delay to allow proper atrial contraction and ventricular filling without being too fast or too slow. Therefore, 0.12–0.20 seconds is the standard normal interval. If the interval is shorter, it can occur with atypical fast conduction or accessory pathways; if it’s longer than 0.20 seconds, it suggests some degree of AV nodal delay, such as first-degree AV block.