WHAT IS ATRIOVENTRICULAR DISSOCIATION?

When the atria and ventricles are governed by two independent pacemakers the condition is called Atrioventricular dissociation. This may be associated with.

1. antegrade block when the pacemaker is located distal to the AV node in the His-Purkinje system; sometimes there is
2. no antegrade block when ventricular pacemaker fires at a rate which is higher than sinus rate and hence sinus impulse cannot reach the ventricle.

Diagnosis of Atrioventricular Dissociation.

AV dissociation is not usually primary diagnosis. It is usually seen in some other rhythm disturbances. The ventricular rate is either equal to atrial (isorhythmic) or greater than atrial rate. In AV block the atrial rate is faster than ventricular rate. Clinicians often use AV block and AV dissociation with same meaning.

This is caused by stimulation of a Junctional or Idioventricular pacemaker or slowing of supraventricular pacemaker with escape rhythm or by SA or AV block associated with escape rhythm. ECG will be helpful in its diagnosis. No treatment is required except for causative arrhythmia.