Final answer:
The PR interval is a segment on an ECG that measures the duration from the beginning of atrial depolarization to the initiation of the QRS complex. A prolonged PR interval (>0.20s) that is consistent in every cycle indicates a delay in the conduction of the electrical impulse from the atria to the ventricles.
Step-by-step explanation:
The PR interval is a segment on an electrocardiogram (ECG) that measures the duration from the beginning of atrial depolarization (the P wave) to the initiation of the QRS complex. It is more clinically relevant than the PR segment as it captures any delay in the passage of the electrical impulse from the sinoatrial (SA) node to the atrioventricular (AV) node. A prolonged PR interval (>0.20s) that is consistent in every cycle indicates a delay in the conduction of the electrical impulse from the atria to the ventricles.