How long can a normal P-R interval range, at a maximum?

The maximum duration of a normal P-R interval is 0.20 seconds. This interval represents the time taken for electrical impulses to travel from the atria through the atrioventricular (AV) node to the ventricles. A P-R interval that exceeds this duration may indicate the presence of a conduction delay, such as first-degree heart block, which can affect the efficiency of the heart's rhythm. Understanding the normal limits of the P-R interval is crucial for identifying potential cardiac issues during assessments of an ECG. If the interval is prolonged beyond 0.20 seconds, it often warrants further investigation by healthcare professionals.