Atrioventricular dissociation
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vendhan Ramanujam M.B.B.S [2]
Synonyms and keywords: AV dissociation
Overview
Atrioventricular (AV) dissociation is an electrocardiographic finding with features of independent functioning of atria and ventricles. It is to be remembered that it is only a descriptive term and not a diagnostic endpoint because the AV dissociation that appears in the electrocardiogram is secondary to some other underlying cardiac rhythm disturbance. Broadly talking, AV dissociation means that the normal association between atrial and ventricular contraction no longer exists and they are independently driven by different pacemakers either for a single beat or forever.
Pathophysiology
The three key underlying pathophysiological mechanisms that would lead to AV dissociation are
- Slowing of the dominant atrial pacemaker (SA node) to an extent that would allow an independent ventricular pacemaker (junctional or ventricular rhythm) response.
- Acceleration of latent pacemakers at junctional or ventricular site (increased automaticity) that would take independent control of ventricles by exceeding the intrinsic atrial rate without a retrograde atrial capture.
- Although controversial yet functionally appealing, a complete heart block would feature with independent activities of atria and ventricle with either atria or ventricle rapid over one another.