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Narrow QRS Tachycardia in Children

Raja Selvaraj MD DNB FCE (Toronto)
Cardiac Electrophysiologist
Professor of Cardiology
JIPMER

Introduction

Narrow QRS tachycardia in children

  • Not a very common presentation
  • Can be a challenging scenario
  • Step wise approach
    • ECG at presentation
    • Adenosine
    • ECG in sinus rhythm
    • Acute management
    • Long term management

Case

  • 9 year old boy
  • Palpitations since 2 hours
  • Otherwise comfortable

ECG at presentation

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Differential diagnoses

  • Atrial tachycardia
    • Focal atrial tachycardia
    • Atrial flutter
  • Atrioventricular reentrant tachycardia
  • Atrioventricular nodal reentrant tachycardia

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So how do we proceed ?

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  • Should be initial drug of choice in most patients with NQRST (and also WQRST)
  • May terminate tachycardia
  • Reponse provides information on mechanism of tachycardia

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Tachycardia termination - What it tells us

  • Mechanism is reentry
  • AV junction dependent tachycardia
  • Some atrial tachycardias may also terminate

"No change in tachycardia"

  • Transient AV block with slowing of rate - not recognised
  • Ventricular tachycardia
  • Not administered properly

Administration of adenosine

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Tachycardia continuation with AV block

  • AV junction independent tachycardia
  • Atrial tachycardia / flutter
  • Rate control possible

Tachycardia terminates and immediately reinitiates

  • Differentiate ventricular rate slowing
  • Termination indicates reentry, reinitiation because of frequent PACs usually
  • Higher doses will not help !
  • DC Cardioversion will not help !

Learning from the sinus rhythm ECG

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Long term management

EP study / ablation

  • Preexcitation - needs evaluation (non invasive or invasive)
  • Recurrent tachycardia, especially drug refractory
  • Incessant tachycardia / LV dysfunction
  • Avoided in very young unless absolutely required

Intermittent preexcitation

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RF ablation

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Pharmacologic management

  • Beta blockers
  • Calcium channel blockers
  • Digoxin
  • Amiodarone
  • Flecainide
  • Ivabradine

Miscellaneous

Ebsteins anomaly

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Fascicular VT

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VA block with Adenosine

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Summary and learning points

  • Adenosine - Diagnostic and therapeutic
  • Preexcitation - Alters prognosis and management strategies
  • RF ablation highly effective - Known when to refer for the same