What does the P-R interval represent in an EKG?

The P-R interval represents the time taken for the electrical impulse to travel from the atria through the atrioventricular (AV) node and into the ventricles. It begins at the onset of the P wave, which signifies atrial depolarization, and ends at the beginning of the QRS complex, which marks the onset of ventricular depolarization. This interval is crucial because it reflects the time required for the electrical signal to traverse the atria and the AV node before reaching the ventricles.

A normal P-R interval suggests that the conduction system of the heart is functioning appropriately, allowing for a coordinated contraction of the heart chambers. If the P-R interval is prolonged or shortened, it may indicate conduction abnormalities, such as first-degree AV block or pre-excitation syndromes, respectively.

The other choices do not accurately describe the P-R interval: it is not specifically related to ventricular contraction duration, does not define the resting phase of the heart, nor does it indicate the time between consecutive heartbeats. These distinctions underscore the significance of the P-R interval in assessing cardiac electrical conduction.