accelerated idioventricular rhythm (AIVR)

Etiology

• acute myocardial infarction (MI)
  • percutaneous coronary intervention after MI
• drug toxicity - digitalis

Pathology

• accelerated idioventricular rhythm (AIVR) generally occurs secondary to increased automaticity from within the terminal Purkinje system of ventricular myocardium
• occurs with reperfusion of infarct-associated coronary artery

Clinical manifestations

• transient & intermittent
• usually asymptomatic
• hemodynamic deterioration may occur in patients who do not tolerate AV asynchrony

Diagnostic procedures

• electrocardiogram:
  • ventricular rate of 60-110/min
    • almost always < 120/min, generally < 100/min
  • ventricular rate usually exceeds spontaneous atrial rate
  • QRS complex usually wide & bizarre
  • intact AV retrograde conduction
    • inverted p-waves after each wide QRS complex
  • retrograde AV block
    • normal QRS complexes preceded by p-waves among wide bizarre QRS complexes (atrial capture)
  • AVIR is suppressed when the atrial rate exceeds the ventricular rate

Differential diagnosis

• left bundle branch block
  • upright monophasic QRS complex in leads I & V6

Management

• AVIR is generally self-limited not requiring therapy within 1st 24 hours after MI
• in symptomatic patients, therapy is directed towards increasing the sinus rate with:
  • atropine
  • isoproterenol
  • overdrive atrial pacing

More general terms

• ventricular arrhythmia
• wide complex tachycardia