What does the PR interval represent in an ECG?

The PR interval in an electrocardiogram (ECG) specifically measures the time it takes for electrical impulses to travel from the atria through the AV (atrioventricular) junction and into the ventricles. It starts at the beginning of the P wave, which reflects atrial depolarization, and ends at the beginning of the QRS complex, which marks the onset of ventricular depolarization.

This interval is crucial as it indicates not only the time required for the electrical signal to pass through the atrial tissues but also the delay that occurs at the AV node, which ensures proper timing between atrial contraction and ventricular filling. A normal PR interval suggests that the conduction system is functioning properly, allowing for synchronized heartbeats. When the PR interval is prolonged, it may indicate a block in the conduction pathway, such as a first-degree AV block.

Understanding the significance of the PR interval helps in diagnosing potential cardiac conditions, making it a vital component of ECG interpretation.