This page provides an introduction to atrial rhythms and links to training materials on this website.
Atrial rhythms originate in the atria, not from the SA node. The P wave's shape can be different from a normal sinus rhythm as the electrical impulse follows a different path. For a complete discussion of atrial rhythm ECG, use our atrial rhythms training module and our practice strips. Atrial rhythms categories:
- Atrial Fibrillation (afib)
- Atrial Flutter
- Premature Atrial Complex
- Multifocal Atrial Tachycardia
- Supraventricular Tachycardia
- Wandering Atrial Pacemaker
- Wolff-Parkinson-White Syndrome
Atrial Rhythm Categories
Sites in the atria are firing very rapidly, between 400-600 bpm. These rapid pacemaking signals cause the atria to quiver. The ventricles beat at a slower rate because the AV node blocks some of the atrial impulses.
There are two types of atrial flutter. Type I (also called classical or typical) has a rate of 250-350 bpm. Type II (also called non-typical) are faster, ranging from 350-450 bpm. ECG tracings will show tightly spaced waves or saw-tooth shaped waveforms (F-waves).
Multifocal Atrial Tachycardia
During multifocal atrial tachycardia, several (non-SA) sites are creating impulses. The P waves will vary in shape and at least three different shapes can be observed. The PR Interval varies. Ventricular rhythm is irregular.
Premature Atrial Complex
Premature atrial complex occurs when an ectopic site within the atria fires an impulse before the next impulse from the SA node. If the ectopic site is near the SA node, the P wave will often have a shape similar to a sinus rhythm. But this P wave will occur earlier than expected.
This term covers three types of tachycardia that originate in the atria, AV junction or SA node.
Wandering Atrial Pacemaker
Wandering atrial pacemaker is an irregular rhythm. In is similar to multifocal atrial tachycardia but the heart rate is under 100 bpm. P waves are present but will vary in shape.
Wolff-Parkinson-White Syndrome occurs when the impulse travels between the atria and ventricles via an abnormal path, called the bundle of Kent. The impulse, not being delayed by the AV node, can cause the ventricles to contract prematurely. ECG characteristics include a shorter PR Interval, longer QRS complex and a delta wave.