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1. AV DISSOCIATION
PHUNG HUY HOANG, MD MSc
Department of Cardiac Arrhythmias
115 Hospital, HCM
June, 2021

2. • AV dissociation = dissociated or independent beating of the atria and ventricles.
• AV dissociation is not a diagnosis, but a “symptom”
• P wave morphology ∈ rhythm controlling the atria (sinus, atrial tachycardia, junctional,
flutter, or fibrillation)

3. AV dissociation
Complete
Incomplete
Both the QRS complex and the P waves appear to
be regularly paced without a fixed temporal
relationship to each other
A QRS complex with a supraventricular contour
occurs early + preceded by a P wave at PR interval
> 0.12s + within a conductible range (ventricular
capture by the supraventricular focus)
A properly timed P wave can be conducted through
to the AV node
No P wave can stimulate the ventricles

4. Gering L. E., Knilans T. K., Surawicz B., et al. (2008), Chou’s Electrocardiography In Clinical Practice, pp. 384-404

5. AV dissociation
Default
Usurpation
Atrial rate becomes slower than the inherent rate
of the subsidiary pacemaker, which acts by default
as an AV junctional or idioventricular escape
mechanism
Increased automaticity of the subsidiary
pacemaker
Junctional or ventricular tachycardia
Sinus bradycardia, sinus arrest, or SA block

6. Balady G. J., Morise A. P. (2019), Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine, Douglas P. Zipes, et al., Editors, Elsevier, pp. 154-174

7. CLASSIFICATION
Balady G. J., Morise A. P. (2019), Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine, Douglas P. Zipes, et al., Editors, Elsevier, pp. 154-174

8. CLASSIFICATION
1
• Slowing of the dominant pacemaker of the heart (usually the sinus node) ➔ allows escape
of a subsidiary or latent pacemaker
• Scenerio: sinus arrhythmia or sinus bradycardia and permit an independent AV junction
rhythm to arise
• When atrial and ventricular rates almost the same = isorhythmic AV dissociation
(imcomplete AV dissociation).
• Not uncommonly, isorhythmic AV dissociation is seen in healthy young individuals
(particularly when they are sleeping)

9. Goldberger A. L., Goldberger Z. D., Shvilki A. (2018), Goldberger’s Clinical Electrocardiography A Simplified Approach, Elsevier, pp. 130-143

10. Goldberger A. L., Goldberger Z. D., Shvilki A. (2018), Goldberger’s Clinical Electrocardiography A Simplified Approach, Elsevier, pp. 130-143

11. CLASSIFICATION
2
• Acceleration of a latent pacemaker (e.g, tachycardia & the atria are not required and that
usurps control of ventricles)
• Scenerio (usually pathologic): nonparoxysmal AV junctional tachycardia, VT without
retrograde atrial capture.

12. Gering L. E., Knilans T. K., Surawicz B., et al. (2008), Chou’s Electrocardiography In Clinical Practice, pp. 384-404

13. Issa Z. F., Zipes D. P., Miller J. M. (2019), Clinical Arrhythmology And Electrophysiology, Elsevier, pp. 255-285

14. CLASSIFICATION
3
• A block (generally at AV junction) ➔ prevents impulses reaching ventricles ➔ ventricles to
beat under control of subsidiary pacemaker
• Scenerio: Junctional or ventricular escape rhythm/AV block (without retrograde
atrial capture
• Complete AV block ≠ complete AV dissociation
• Complete AV block have complete AV dissociation.
• Complete AV dissociation may or may not have complete AV block

15. Scherlag et al. divided escape rhythm into two types.
1st type 2nd type
Rate (bpm) 45-60 35-45
Atropin response (+) Not significantly changed
Location Proximal to His bundle His bundle
Gering L. E., Knilans T. K., Surawicz B., et al. (2008), Chou’s Electrocardiography In Clinical Practice, pp. 384-404

16. Issa Z. F., Zipes D. P., Miller J. M. (2019), Clinical Arrhythmology And Electrophysiology, Elsevier, pp. 255-285

17. Issa Z. F., Zipes D. P., Miller J. M. (2019), Clinical Arrhythmology And Electrophysiology, Elsevier, pp. 255-285

18. CLASSIFICATION
4
• A combination of causes.
• E.g, excess digitalis ➔ production of nonparoxysmal AV junctional tachycardia //
sinoatrial (SA) or AV block

19. Wagner G. S., Strauss D. G. (2014), Marriott's Practical Electrocardiography, Wolters Kluer, pp. 353-378

20. 1. Gering L. E., Knilans T. K., Surawicz B., et al. (2008), "Atrioventricular Junctional Rhythms", Chou’s Electrocardiography In
Clinical Practice, Saulders Elsevier, pp. 384-404.
2. Goldberger A. L., Goldberger Z. D., Shvilki A. (2018), "Atrioventricular (AV) Conduction Abnormalities, Part I: Delays, Blocks,
and Dissociation Syndromes", Goldberger’s Clinical Electrocardiography A Simplified Approach, Elsevier, pp. 172-182.
3. Issa Z. F., Zipes D. P., Miller J. M. (2019), "Atrioventricular Conduction Abnormalities", Clinical Arrhythmology And
Electrophysiology, Elsevier, pp. 255-285.
4. Olgin J. E., Zipes D. P. (2019), "Bradyarrhythmias and Atrioventricular Block", Braunwald’s Heart Disease: A Textbook of
Cardiovascular Medicine, Douglas P. Zipes, et al., Editors, Elsevier, pp. 772-780.
5. Wagner G. S., Strauss D. G. (2014), "Reentrant Atrial TachyarrhythmiasThe Atrial Flutter/Fibrillation Spectrum", Marriott's
Practical Electrocardiography, Wolters Kluer, pp. 353-378.
REFERENCES