Narrow Complex Tachycardia

Two main categories:

1. AV node independent
2. AV node dependent

AV NODE INDEPENDENT

• sinus tachycardia
• atrial tachycardia (unifocal/multifocal)
• atrial fibrillation
• atrial flutter

AV NODE DEPENDENT

• Pre-excitation syndromes
• AV node re-entry tachycardia
• junctional tachycardia

MANAGEMENT

Undifferentiated Narrow Complex Tachycardia

• vagal manoeuvre
• adenosine 6-12mg IV (half dose if cardiac transplant or on dipryidamole)

• AV node independent: decreased AV node conduction but tachycardia persists
• AV node dependent: arrhythmia ceases

Ventricular stand-still post Adenosine

• wait! (typically resolves after a few seconds)
• theophylline 250mcg
• atropine
• adrenaline
• CPR

AV NODE INDEPENDENT

• Sinus tachycardia
  • treat cause!

• Atrial tachycardia (unifocal or multifocal)
  • diagnose by taking an atrial electrogram (CVL, atrial epicardial, oesophageal)
  • stop digoxin and theophylline (cause or worsen arrhythmia)
  • Mg2+
  • K+
  • amiodarone
  • beta-blocker — sotalol if unifocal
  • synchronized cardioversion
• Atrial fibrillation
  • stable: treat cause, cardiovert (replace electrolytes, amiodarone, flecanide), rate control (beta blockers, digoxin, amiodarone, sotalol, Ca2+ channel blockers), anti-coagulation
  • unstable: synchronized cardioversion
• Atrial flutter
  • type I: rate 240-320 -> can overdrive pace
  • type II: rate 340-430 -> can’t overdrive pace
  • drugs: digoxin, diltiazem, beta blockers, sotalol, flecanide, procainamide and amiodarone
  • synchronised cardioversion (25-50J)

AV NODE DEPENDENT

• AV Node Re-entry Tachycardia/ AV Re-entry Tachycardia
  • vagal manoeuvres
  • adenosine
  • verapamil
  • sotalol
  • amiodarone
  • flecanide
  • overdrive pacing
  • cardioversion
• Avoidance of verapamil as leads to rapid conduction down accessory pathway (WPW).

• Junctional Tachycardia
  • amiodarone
  • flecanide