Accelerated Junctional Rhythm (AJR) – The Premier EKG Resource for Medical Professionals – EKG MD

Overview

Tachyarrhythmia caused by increased automaticity in his bundle pacemaking cells
Occurs when the rate of an AV junctional pacemaker exceeds that of the sinus node
Arises when there is increased automaticity in the AV node coupled with decreased automaticity in the sinus node

Junctional rhythm classification by rate

Junctional rhythm classification by etiology

Automatic junctional rhythms (e.g. AJR) = due to enhanced automaticity in AV nodal cells
Re-entrant junctional rhythms (e.g. AVNRT) = due to re-entrant loop involving AV node

ECG Features

Regularity: regular
Ventricular rate: 60–100 BPM
QRS duration: normal (< 120 ms), unless pre-existing bundle branch block or rate-related aberrant conduction
Retrograde P waves may be present and can appear before, during, or after the QRS complex; usually inverted in the inferior leads (II, III, aVF), upright in leads aVR and V1
AV dissociation may be present with the ventricular rate usually greater than the atrial rate
May be associated ECG features of digoxin effect or toxicity

Causes

Drugs: digoxin toxicity (classic cause of AJR), beta-agonists (e.g. isoprenaline, adrenaline)
Others: myocardial ischemia, myocarditis, cardiac surgery

Differential Diagnosis

Rapid AJR may be difficult to distinguish from re-entrant junctional tachycardias (e.g. AVNRT, AVRT)
Irregularity of rhythm and heart-rate variability are suggestive of automatic junctional tachycardia
Automatic junctional tachycardia is typically non-responsive to vagal maneuvers; there may be some transient slowing of the ventricular rate, but reversion to sinus rhythm will not occur
AJR with aberrant conduction may be difficult to distinguish from accelerated idioventricular rhythm; presence of fusion or capture beats indicates a ventricular rather than junctional focus

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