Polymorphic ventricular tachycardia

Background

Etiologies

Clinical Features

Differential Diagnosis

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise

  • A-fib/flutter with variable AV conduction AND bundle branch block (fixed or rate-related)
  • A-fib/flutter with variable AV conduction AND accessory pathway (e.g. WPW)
  • A-fib + hyperkalemia

Evaluation

  • Evaluate for underlying causes (e.g. electrolyte imbalances, ACS)

ECG Findings

  • Wide QRS (>100ms or 3 small boxes)
  • QRS complexes of varied amplitude, axis and duration
      • Torsades: QRS complexes appear to twist around isoelectric line
  • Rapid rhythm (usually 140-160 bpm, but can be up to 300 bpm)
  • Irregular

Management

Pulseless

See Adult pulseless arrest and Pediatric pulseless arrest

Unstable

  • Unsynchronized cardioversion (defibrillation) 200J (or 2J/kg for pediatrics)
  • Correct any electrolyte abnormalities

Stable

  • Correct any electrolyte abnormalities
  • Torsades:
    • Magnesium sulfate (for Torsades):
      • 1-2gm IV, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
      • Peds: 25-50mg/kg (max 2g) IV
    • Sotalol (100mg IV over 5 minutes)
    • Isoproterenol, 2-8 mcg/min
    • Overdrive Pacing to goal HR 90-120
    • Avoid procainamide, amiodarone (may further prolong QT)
  • Non-Torsades
    • Amiodarone, agent of choice in setting of AMI or LV dysfunction
      • 150 mg over 10min (15 mg/min), followed by 1 mg/min drip over 6hrs (360 mg total), then 0.5 mg/min drip over next 18 hrs (540 mg total)
      • Peds: 5mg/kg (max 300mg), may repeat twice
    • Procainamide
      • 100 mg q5min until termination of arrhythmia, then start 2-6 mg/min (or 1-2 mg/min for renal/cardiac failure)
      • Max dose 17mg/kg OR widening of QRS >50%
    • Lidocaine, 1-1.5mg/kg IV q5min, repeat PRN up to 300mg/hr

Refractory

Disposition

  • Admit, even if back in normal sinus rhythm

See Also

External Links

References