In electrocardiography P-Q interval represents

The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. The PR interval spans the time required for the propagating impulse to advance from the atria through the AV node, bundle of His, bundle branches, and the system of Purkinje fibers until the ventricular myocardium begins to depolarize. It does not include the duration of conduction from the SA node to the right atrium (SA conduction).