AV dissociation
Also calledAVD · atrioventricular dissociation
Definition
Independent activation of the atria and ventricles by two separate pacemakers, so P waves and QRS complexes follow their own rates with no consistent relationship between them. It is a finding rather than a single diagnosis and can arise when the sinus rate slows enough for a junctional or ventricular pacemaker to take over, when a lower pacemaker (for example an accelerated junctional rhythm or ventricular tachycardia) speeds up past the sinus rate, or with complete (third-degree) AV block. Comparing the rates helps: in complete AV block the atrial (sinus) rate is faster than the ventricular escape rate, when a faster lower pacemaker takes over the atrial rate is slower than the ventricular rate, and in isorhythmic dissociation the two rates are similar.
Clinical noteAV dissociation is not synonymous with complete heart block: when it comes from sinus slowing or a faster lower pacemaker, AV conduction can be intact, and dissociated atrial impulses may still conduct as capture or fusion beats.
Sources
- Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. Circulation. 2019;140(8):e382-e482. doi.org/10.1161/CIR.0000000000000628
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
- Wellens HJ, Bär FW, Lie KI. The value of the electrocardiogram in the differential diagnosis of a tachycardia with a widened QRS complex. Am J Med. 1978;64(1):27-33. doi.org/10.1016/0002-9343(78)90176-6
- Antzelevitch C, Burashnikov A. Overview of basic mechanisms of cardiac arrhythmia. Card Electrophysiol Clin. 2011;3(1):23-45. doi.org/10.1016/j.ccep.2010.10.012
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.