The PR interval is a measurement on an electrocardiogram (ECG) that represents the time it takes for electrical impulses to travel from the atria to the ventricles of the heart. It starts at the beginning of the P wave, which indicates atrial depolarization, and ends at the beginning of the QRS complex, which signifies ventricular depolarization. A normal PR interval typically ranges from 120 to 200 milliseconds. An abnormal PR interval can indicate various heart conditions. A prolonged PR interval may suggest atrioventricular (AV) block, while a shortened PR interval could be associated with Wolff-Parkinson-White syndrome. Monitoring the PR interval is essential for assessing heart health and diagnosing potential issues.