Junctional tachycardia

Background

• Rare
• Cardiac impulses originate at the AV junction
  • AV node
  • Bundle of His
• Also referred to as Junctional Ectopic Tachycardia (JET) or Congenital Ectopic Tachycardia (CJET) if present at birth
• Rate exceeds the upper limit seen in normal sinus rhythm
  • In adults, >100 bpm
  • In pediatric patients it varies by age until age 8 or 9 (see pediatric vital signs)

Junction Rhythm Classification

Arbitrarily classified by rate

• Junctional escape rhythm: 40-60 bpm
• Accelerated junctional rhythm: 60-100 bpm
• Junctional tachycardia: >100 bpm

Clinical Features

• Clinical features vary widely, diagnosis usually made via ECG
• Past medical hx may include recent cardiovascular surgery

Differential Diagnosis

Narrow-complex tachycardia

• Regular
  • AV Node Independent
    • Sinus tachycardia
    • Atrial tachycardia (uni-focal or multi-focal)
    • Atrial fibrillation
    • Atrial flutter
    • Idiopathic fascicular left ventricular tachycardia
  • AV Node Dependent
    • Paroxysmal supraventricular tachycardia (PSVT)
      • AV node re-entry tachycardia (AVNRT)
      • AV re-entry tachycardia (AVRT)
        • Lown-Ganong-Levine syndrome
        • Wolff–Parkinson–White syndrome
    • Junctional tachycardia
• Irregular
  • Multifocal atrial tachycardia (MAT)
  • Sinus tachycardia with frequent PACs, PJCs, PVCs
  • Atrial fibrillation
    • Atrial fibrillation with RVR
  • Atrial flutter with variable conduction
  • Digoxin Toxicity

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

• Regular
  • Monomorphic ventricular tachycardia
  • PSVT with aberrant conduction:
    • PSVT with bundle branch block^
    • PSVT with accessory pathway
    • Atrial flutter with bundle branch block^
  • Sinus tachycardia with bundle branch block^
  • Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
  • Metabolic
    • Hyperkalemia
    • Digoxin toxicity
    • Severe metabolic acidosis
• Irregular
  • Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
  • Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
  • Atrial fibrillation + hyperkalemia
  • Polymorphic ventricular tachycardia
    • Torsades de pointes
    • Nonsustained ventricular tachycardia

^Fixed or rate-related

Evaluation

ECG showing junctional tachycardia. Note narrow complex QRS, no P waves, and accelerated rate.

• ECG findings
  • P waves
    • may be antegrade, retrograde, or absent depending on depolarization of the atrial relative to the ventricles
  • QRS complexes
    • Narrow in the absence of aberrancy
• May be distinguished from AVNRT via Adenosine administration
  • If JET is present, atrial depolarization will briefly terminate and reveal AV dissociation
  • If AVNRT is present, conversion to sinus rhythm will likely occur
  • Avoid administration in the setting of aberrancy
  • JET will concomitant 3 degree AVB is rare
• Consider JET underlying causes to include
  • Electrolyte abnormalities
  • Acidosis
  • Cardiovascular surgery within 24-48 hrs

Management

• Amiodarone 2 mg/kg bolus.
  • If necessary, as continuous infusion at 10 to 15 mcg/kg/min

See Also

• Paroxysmal supraventricular tachycardia
• Tachycardia (Narrow)
• ACLS: Tachycardia
• PALS: Tachycardia