P Wave - EKG Basics.
The P wave represents atrial depolarization. In a normal EKG, the P-wave precedes the QRS complex. It looks like a small bump upwards from the baseline. The amplitude is normally 0.05 to 0.25mV (0.5 to 2.5 small boxes). Normal duration is 0.06-0.12 seconds (1.5 to 2.75 small boxes). The shape of a P-wave is usually smooth and rounded.