• When there is a transient sinus pause, an atrial escape beat arises from the atrial automaticity focus and is conducted down the AV node-His bundle-Purkinje system.
• The resulting beat has a new P’ wave that appears distinctively from normal sinus P waves as well as a normal QRS complex.
• As soon as the sinus node resumes its pacemaking activity, the original sinus rhythm also returns to baseline.
• An atrial escape rhythm arises when there is a sinus arrest, the atrial automaticity focus takes over for a longer period of time and sends its own impulses down the AV node-His bundle-Purkinje system.
• The resulting rhythm runs at a new rate (inherent atrial rate at 60-80 bpm) and consists of new P’ waves followed by normal QRS complexes.
• Wandering atrial pacemaker rhythm arises when ectopic impulses “wander” from multiple atrial automaticity foci.
• The resulting rhythm has varied P’ wave morphologies that are distinctive for each atrial focus.
• Rate is often normal, < 100bpm, if > 100bpm, it’s called multifocal atrial tachycardia (MAT).
