atrioventricular dissociation

dissociation

 [dis-so″she-a´shun]

1. the act of separating or state of being separated.

2. the separation of a molecule into fragments produced by the absorption of light or thermal energy or by solvation.

3. segregation of a group of mental processes from the rest of a person's usually integrated functions of consciousness, memory, perception, and sensory and motor behavior, as in the separation of personality and aspects of memory or subpersonalities in the dissociative disorders or in the segregation of an idea or object from its emotional significance, as is sometimes seen in schizophrenia.

atrial dissociation independent beating of the left and right atria, each with normal rhythm or with various combinations of normal rhythm, atrial flutter, or atrial fibrillation.

atrioventricular dissociation a condition in which the atria and the ventricles contract independently of each other, without synchronization of their rhythms.

electromechanical dissociation pulseless electrical activity.

isorhythmic atrioventricular dissociation a cardiac rhythm in which the atria and the ventricles beat independently and at approximately the same rate.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

a·tri·o·ven·tric·u·lar dis·so·ci·a·tion (AVD),

, AV dissociation [MIM*209600]

1. any situation in which atria and ventricles are activated and contract independently, as in complete AV block;

2. more specifically, the dissociation between atria and ventricles that results from slowing of the atrial pacemaker or acceleration of the ventricular pacemaker at nearly (although rarely exactly) equal rates, each depolarizing its own chamber, thus interfering with depolarization by the other (interference-dissociation).

Farlex Partner Medical Dictionary © Farlex 2012

atrioventricular dissociation

n.

A condition in which the atria and ventricles contract independently, especially as resulting from the slowing of an atrial pacemaker or the acceleration of a ventricular pacemaker.

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

atrioventricular dissociation

The independent depolarisation of the atria and ventricles, where atrial rhythm is controlled by one pacemaker and the ventricular rhythm is controlled by another, accompanied by atrioventricular dyssynchrony. Atrioventricular dissociation is not a primary condition in itself, but rather a symptom of an underlying dysrhythmia due to one of a number of causes that prevent the normal transmission of AV impulses:
• Slowing of the dominant pacemaker (usually the sinus node), which allows escape of a subsidiary (latent) pacemaker;
• Acceleration of a latent pacemaker, which wrests control of the ventricles and is accompanied by a pathologically enhanced rate of discharge;
• AV or 3rd-degree block, which prevents normal impulses from a dominant pacemaker from reaching the ventricles, allowing them to beat under the control of the subsidiary pacemaker.

Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

atrioventricular dissociation

AV dissociation Cardiology The independent depolarization of the atria and ventricles, where atrial rhythm is controlled by one pacemaker and the ventricular rhythm is controlled by another, accompanied by a loss of A-V synchrony. See Third-degree block.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.