The PR interval is the time from the beginning of the P wave (atrial depolarization) to the beginning of the QRS complex (ventricular depolarization). The normal PR interval measures 0.12-0.20 ...

When left atrial enlargement occurs ... P-mitrale occurs when the depolarization of the right atrium and left atrium are both visible in the P wave. This is seen as a notch in the P wave and ...