What is the normal range for the PR interval in a standard ECG?

The normal range for the PR interval in a standard ECG is defined as 120 to 200 milliseconds. The PR interval measures the time from the onset of atrial depolarization (the start of the P wave) to the onset of ventricular depolarization (the start of the QRS complex). This interval reflects the time it takes for electrical impulses to travel from the atria through the AV node to the ventricles.

A PR interval within this 120 to 200 milliseconds range indicates that the conduction through the AV node and the surrounding tissues is functioning properly, signaling effective communication between the atria and ventricles. If the PR interval is shorter than 120 milliseconds, it may suggest a pre-excitation syndrome or other forms of abnormal conduction, while a PR interval longer than 200 milliseconds indicates potential heart block.

In summary, a PR interval of 120 to 200 milliseconds is essential for maintaining coordinated heart function, and understanding this range is crucial for interpreting ECGs accurately in clinical practice.