Atrioventricular Dissociation

Author: Chirag M Sandesara, MD; Chief Editor: Jeffrey N Rottman, MD more...

Updated: Apr 30, 2008

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Background
Pathophysiology
Epidemiology
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Background

Atrioventricular (AV) dissociation is a condition in which the atria and ventricles do not activate in a synchronous fashion but beat independent of each other. AV dissociation usually refers to the situation in which the ventricular rate is the same or faster than the atrial rate.^{[1, 2]}When the atrial rate is faster and the atria and ventricles are beating independently, complete heart block is present; this is distinct from AV dissociation. While complete heart block can be properly considered a form of AV dissociation, it is discussed in detail in Atrioventricular Block and is not considered further in this article. Also, in AV dissociation, no retrograde ventriculoatrial conduction occurs.

When the atrial rate is the same as the ventricular rate but the P wave is not conducting, the rhythm disturbance is known as isorhythmic AV dissociation. When the rates are similar but occasionally the atria conduct to the ventricles, the rhythm is known as interference AV dissociation.

AV dissociation can be a benign phenomenon and can be complete or incomplete. When incomplete, some of the P waves conduct and capture the ventricles (ie, interference AV dissociation), but if they do not, it is complete AV dissociation. Complete AV dissociation can mimic AV block, but the fact that none of the P waves conduct has more to do with timing of the P waves in relation to the QRS complex rather than the presence of AV block.

Pathophysiology

A normal cardiac impulse arises from the sinus node and is conducted through the AV junction, the bundle of His, and the bundle branches to the ventricles. The sinus node is the dominant pacemaker because its intrinsic rate is faster than subsidiary pacemakers in the AV junction or in the ventricle. AV dissociation can result from (1) slowing of the dominant pacemaker (sinus node), which allows an escape junctional or ventricular rhythm, or (2) acceleration of a normally slower (subsidiary) pacemaker, such as a junctional site or a ventricular site that activates the ventricles without retrograde atrial capture.

Conditions that can initiate AV dissociation include surgical and anesthesia interventions (including intubation), conditions that increase catecholamine levels (including infusions of inotropes) and drugs that block catecholamines, sinus node disease, digoxin toxicity, myocardial infarction and other structural heart disease, hyperkalemia, vagal activation (eg, neurocardiogenic syncope, vomiting), ventricular tachycardia, or ventricular pacing. AV dissociation can be seen after radiofrequency ablation of the slow pathway responsible for AV nodal reentry if some of the vagal fibers are damaged. After exertion, if AV dissociation is present from an escape pacer, it can be a normal phenomenon. Whatever the cause, AV dissociation usually is secondary to some other cause.

Frequency

International

Little epidemiologic information is available regarding the frequency of AV dissociation.

Mortality/Morbidity

AV dissociation by itself can be benign. Any adverse effects are related to ensuing bradycardia, AV dyssynchrony, or underlying conditions.

Proceed to Clinical Presentation

Contributor Information and Disclosures

Author

Chirag M Sandesara, MD Virginia Cardiovascular Associates, Cardiac Rhythm Care

Chirag M Sandesara, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians-American Society of Internal Medicine, American Heart Association, American Medical Association, and Heart Rhythm Society

Disclosure: Nothing to disclose.

Coauthor(s)

Brian Olshansky, MD Professor of Medicine, Department of Internal Medicine, University of Iowa College of Medicine

Brian Olshansky, MD is a member of the following medical societies: American Autonomic Society, American College of Cardiology, American College of Chest Physicians, American College of Physicians, American College of Sports Medicine, American Federation for Clinical Research, American Heart Association, Cardiac Electrophysiology Society, Heart Rhythm Society, and New York Academy of Sciences

Disclosure: Guidant/Boston Scientific Honoraria Speaking and teaching; Medtronic Honoraria Speaking and teaching; Guidant/Boston Scientific Consulting fee Consulting; Novartis Honoraria Speaking and teaching; Novartis Consulting fee Consulting

Ram C Sharma, MD, MRCP Assistant Professor of Medicine, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Louisville

Ram C Sharma, MD, MRCP is a member of the following medical societies: American Academy of Sleep Medicine, American College of Cardiology, and Royal College of Physicians of the United Kingdom

Disclosure: Nothing to disclose.

Roger Freedman, MD Director of Clinical Cardiology, Professor, Department of Internal Medicine, Division of Cardiology, University of Utah School of Medicine

Roger Freedman, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Heart Association, Heart Rhythm Society, Phi Beta Kappa, and Sigma Xi

Disclosure: St. Jude Medical Grant/research funds Other; St. Jude Medical Consulting fee Consulting; St. Jude Medical Ownership interest Other; Boston Scientific Grant/research funds Other; Boston Scientific Consulting fee Consulting; Medtronic Grant/research funds Other; Medtronic Consulting; Sorin Consulting fee Consulting

Specialty Editor Board

Alan D Forker, MD Professor of Medicine, University of Missouri at Kansas City School of Medicine; Director, Outpatient Lipid Diabetes Research, MidAmerica Heart Institute of St Luke's Hospital

Alan D Forker, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, American Society of Hypertension, and Phi Beta Kappa

Disclosure: Research Grant Grant/research funds Hospital contracts to do research; I am a hospital employee with no personal profit; Speakers Bureau Honoraria Speaking and teaching

Francisco Talavera, PharmD, PhD Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

Marschall S Runge, MD, PhD Charles and Anne Sanders Distinguished Professor of Medicine, Chairman, Department of Medicine, Vice Dean for Clinical Affairs, University of North Carolina at Chapel Hill School of Medicine

Marschall S Runge, MD, PhD is a member of the following medical societies: American Association for the Advancement of Science, American College of Cardiology, American College of Physicians-American Society of Internal Medicine, American Federation for Clinical Research, American Federation for Medical Research, American Heart Association, American Physiological Society, American Society for Clinical Investigation, American Society for Investigative Pathology, Association of American Physicians, Association of Professors of Cardiology, Association of Professors of Medicine, Southern Society for Clinical Investigation, and Texas Medical Association

Disclosure: Pfizer Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching; Orthoclinica Diagnostica Consulting fee Consulting

Amer Suleman, MD Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital

Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions

Disclosure: Nothing to disclose.

Chief Editor

Jeffrey N Rottman, MD Professor of Medicine and Pharmacology, Director, Clinical Cardiac Electrophysiology Fellowship Program, Vanderbilt University School of Medicine; Chief, Department of Cardiology, Nashville Veterans Affairs Medical Center

Jeffrey N Rottman, MD is a member of the following medical societies: American Heart Association and North American Society of Pacing and Electrophysiology (NASPE)

Disclosure: Nothing to disclose.

References

Braunwald E. Atrioventricular dissociation. In: Braunwald E, Zipes DP, Libby P, eds. Heart Diseases: A Textbook Of Cardiovascular Medicine. 6^th ed. WB Saunders Co: Philadelphia, Pa; 2001.
Wagner GS. Atrioventricular dissociation. In: Wagner GSS, Marriott HJ, eds. Marriott's Practical Electrocardiography. 9th ed. Baltimore, Md: Williams & Wilkins; 1994.
Oreto G, Smeets JL, Rodriguez LM, et al. Wide complex tachycardia with atrioventricular dissociation and QRS morphology identical to that of sinus rhythm: a manifestation of bundle branch reentry. Heart. Dec 1996;76(6):541-7. [Medline].
Duffield JS, Jacob AJ, Miller HC. Recurrent, life-threatening atrioventricular dissociation associated with toxoplasma myocarditis. Heart. Nov 1996;76(5):453-4. [Medline].
Luzza F, Oreto G. Pseudo-atrioventricular dissociation caused by interpolated ventricular extrasystoles in the presence of dual atrioventricular nodal pathway. Chest. May 1994;105(5):1587-9. [Medline].
Pick A. A-V dissociation. A proposal for a comprehensive classification and consistent terminology. Am Heart J. Aug 1963;66:147-50. [Medline].

Atrioventricular (AV) dissociation. Ventricular tachycardia and complete AV dissociation. P waves are marked.

Atrioventricular (AV) dissociation. Complete AV block and no fixed relationship between P waves and QRS complexes.

Diagnostic algorithm for atrioventricular dissociation.

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