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)

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

Evaluation

• 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

Disposition

• 4-9% mortality rate in CJET
• Refractory JET may require catheter ablation