Ectopic atrial rhythm

Ectopic atrial rhythms occur when the impulses for the atria to beat are generated in the wrong area. This results in p waves on the electrocardiogram which differ from the normal appearance of p waves. The rate usually remains at less than 100 beats per minute.

1. There is a different P wave morphology than in normal sinus rhythm (NSR)
2. The sinus rate is < 100 beats per minute
3. The rhythm is called an accelerated atrial rhythm when the rate is faster than the patient’s own NSR but < 100 beats per minute.

Shown below is an EKG showing ectopic atrial rhythm. In this example, the sinus node stopped pacing due to ischemia during an atrial infarction. The P wave is positive in lead I, and negative in III, and aVF. The atrial pacemaker is thus situated at the bottom of the right atrium, close to the AV node.

Copyleft images obtained courtesy of ECGpedia, http://en.ecgpedia.org

• National Heart, Lung, and Blood Institute, Diseases and Conditions Index

1. Hammill S. C. Electrocardiographic diagnoses: Criteria and definitions of abnormalities, Chapter 18, MAYO Clinic, Concise Textbook of Cardiology, 3rd edition, 2007 ISBN 0-8493-9057-5

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