Idiopathic fascicular left ventricular tachycardia

Background

• Also known as fascicular tachycardia, idiopathic fascicular left ventricular tachycardia (ILFVT), Belhassen-type VT, verapamil-sensitive VT, or intrafascicular tachycardia
• Re-entrant tachycardia seen typically in young patients without structural heart disease

Clinical Features

• young adult
• male (60-80%)
• palpitations
• dizziness
• syncope is infrequent

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

Management

Unstable

Synchronized Cardioversion

• Adults: 0.5-1.0 J/kg
• Pediatrics: 0.5-1 J/kg
  • If unsuccessful, increase to 2 J/kg
• Consider sedation prior to cardioversion only if it will not significantly delay the procedure

Stable

Vagal Maneuvers

• IFLVT does not usually respond to this treatment

Adenosine

• IFLVT does not usually respond to this treatment

Beta blockers

• IFLVT does not usually respond to this treatment

Verapamil

• 10 mg over 1 min
  • only administer in stable patients with an established diagnosis of IFLVT