What is the duration of a normal PR interval on an EKG?

The duration of a normal PR interval on an EKG is typically between 0.12 to 0.20 seconds, which can also be expressed as 120 to 200 milliseconds. This interval represents the time it takes for electrical impulses to travel from the atria to the ventricles, specifically through the atrioventricular (AV) node. A PR interval within this range indicates normal conduction through the AV node.

If the PR interval exceeds 0.20 seconds, it may suggest a condition known as first-degree AV block, where the conduction through the AV node is prolonged. Conversely, if the PR interval is shorter than 0.12 seconds, it could indicate a condition called pre-excitation syndromes, such as Wolff-Parkinson-White syndrome, where there is an additional pathway for impulses to bypass the normal conduction system. Understanding the range of a normal PR interval is crucial for interpreting EKGs accurately in clinical practice.