AV Dissociation

Created by team@ekgdx.com on Dec. 27, 2023

Let’s talk about AV Dissociation

AV (atrioventricular) dissociation is often misunderstood or misused term because is not an arrhythmia. AV Dissociation is a condition whereby the atria and the ventricles activate independently of each other. The ventricular rate is usually slower then the atrial rate. 

AV dissociation may be classified as follows:

  1. AV dissociation by default: when the rate of the dominant atrial pacemaker slows down, the subsidiary pacemaker (AV node) takes over. Conditions include: Sick sinus syndrome, sinus arrest, post-cardioversion, high vagal tone, others.
  2. AV dissociation by usurpation: When the rate of the subsidiary pacemaker increases above the intrinsic atrial rate. Conditions include: Digitalis toxicity, myocardial ischaemia, junctional or ventricular tachycardia, others.

Note: Isorhythmic AV dissociation is considered when both atrial and ventricular rates are approximately the same, resulting in apparent association of the rhythms, but the PR intervals vary slightly. See case A66 of our Volumen II

 

Sinus rhythm (blue arrows) with varying PR intervals (green arrows) and a slow regular ventricular rate consistent with AV dissociation and complete or third degree AV block

 

What type of AV dissociation is present in this EKG? What else do you see? More cases available in EKGDX

 

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Dr. Roig

AV Dissociation