• Pacemaker site transfers from the SA node to other latent pacemaker sites in the atria and the atrioventricular (AV) junction and then moves back to the SA node.

Rate: Normal (60–100 bpm)

Rhythm: Irregular

P Waves: At least three different forms, determined by the focus in the atria

PR Interval: Variable; determined by focus

QRS: Normal (0.06–0.10 sec)

Clinical Tip: WAP may occur in normal hearts as a result of fluctuations in vagal tone.