Accelerated idioventricular rhythm

Background

• Results when rate of an ectopic ventricular pacemaker exceeds sinus node
• Usually benign,self limiting
• Terminology
  • Idioventricular rhythm: 20-40 bpm
  • Accelerated idoventricular rhythm: 40-120 bpm
  • Ventricular tachycardia: >120 bpm

Causes

• Reperfusion phase of acute myocardial infarction (most common cause)
• Beta-sympathomimetics (isoprenaline or adrenaline)
• Drug toxicity, especially digoxin, cocaine and volatile anaesthetics such as desflurane
• Electrolyte abnormalities
• Cardiomyopathy
• congenital heart disease
• myocarditis
• Return of spontaneous circulation (ROSC) following cardiac arrest
• Athletic heart

Clinical Features

• Asymptomatic or palpitations

Differential Diagnosis

Palpitations

• Arrhythmias:
  • Atrial fibrillation
  • Grouped beats on ECG (commonly misdx as A-fib)
    • Atrial bigeminy and trigeminy
    • Mobitz I or Mobitz II
  • Atrial flutter
  • SVT
  • Ventricular Tachycardia
  • Sick sinus syndrome
  • Multifocal atrial tachycardia
  • PVCs
  • Wolff–Parkinson–White syndrome (WPW)
  • Sinus node dysfunction
  • AV Block
  • Lown-Ganong-Levine Syndrome‎
  • Accelerated idioventricular rhythm
• Non-arrhythmic cardiac causes:
  • Cardiomyopathy
  • CHF
  • Mitral valve prolapse
  • Congenital heart disease
  • Pericarditis
  • Valvular disease
  • Pacemaker malfunction
  • Acute MI
• Psychiatric causes:
  • Anxiety disorder
  • Panic attack
• Drugs and Medications:
  • Alcohol
  • Caffeine
  • Meds (i.e. digitalis, theophylline)
  • Street drugs (i.e. cocaine)
  • Tobacco
• Misc
  • Hyperthyroidism

Evaluation

ECG features

• Regular rhythm
• Rate 50-110 bpm
• Three or more ventricular complexes
• QRS complexes >120ms
• Fusion and capture beats

Management

• AIVR is a benign rhythm in most settings and does not usually require treatment
• Self limiting and resolves when sinus rate exceeds that of the ventricular foci
• Anti-arrhythmics may cause precipitous haemodynamic deterioration and should be avoided
• Treat the underlying cause: e.g. correct electrolytes, restore myocardial perfusion
• Patients with low-cardiac-output states (e.g. severe biventricular failure) may benefit from restoration of AV synchrony to restore atrial kick – in this case atropine may be trialled to increase sinus rate and AV conduction

Disposition

• Normally outpatient

External Links

• http://lifeinthefastlane.com/ecg-library/aivr/

References

Authors

Ross Donaldson