Torsades de pointes: Difference between revisions

 
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*Form of polymorphic [[VTach]]
*Form of polymorphic [[VTach]]
**Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
**Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
*Associated with congenital or acquired [[prolonged QT]]
*Associated with congenital or acquired [[prolonged QT]] which may be secondary to medications


===Common Causes===
===Common Causes===
'''POINTES''' mnemonic:
'''POINTES''' mnemonic:
*'[[Phenothiazines|''P'''henothiazines]]
*[[Phenothiazines|'''P'''henothiazines]]
*'''O'''ther medications (ie [[TCAs]])
*'''O'''ther medications (ie [[TCAs]])
*'[[ICH|''I'''ntracranial bleed]]
*[[ICH|'''I'''ntracranial bleed]]
*'''N'''o known cause (idiopathic)
*'''N'''o known cause (idiopathic)
*'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide)
*'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide)
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==Management==
==Management==
Increasing HR decreases QT interval
''Increasing HR decreases QT interval''
#[[Magnesium sulfate]] - decreases calcium influx
#[[Magnesium sulfate]] - decreases calcium influx
#*1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
#*1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
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#[[Defibrillation]] / [[synchronized cardioversion]] - Patient in extremis
#[[Defibrillation]] / [[synchronized cardioversion]] - Patient in extremis
#'''AVOID''' amiodarone and procainamide, which may worsen prolonged QT
#'''AVOID''' amiodarone and procainamide, which may worsen prolonged QT
# Lidocaine (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes.
# [[Lidocaine]] (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes
#*[[Lidocaine]] 1 mg/kg bolus, followed by 0.5-4 mg/min, titrated to rhythm response<ref>Reachi B, Negrelli J, Hickman A, Beesley S, Osborn J (2019) Isoproterenol and Lidocaine for Recurrent Torsades de Pointes in a 32-year-old Pregnant Woman. Int J Crit Care Emerg Med 5:092.</ref>
#*Inpatient may monitor plasma lidocaine levels, with goal < 6 mcg/mL


==Disposition==
==Disposition==
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*[[Tachycardia (Wide)]]
*[[Tachycardia (Wide)]]
*[[ACLS (2010 Guidelines)]]
*[[ACLS (2010 Guidelines)]]
*[[In-Training Exam Review]]


==References==
==References==

Latest revision as of 22:10, 7 September 2022

Background

  • Form of polymorphic VTach
    • Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
  • Associated with congenital or acquired prolonged QT which may be secondary to medications

Common Causes

POINTES mnemonic:

Clinical Features

Differential Diagnosis

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

^Fixed or rate-related

Evaluation

Workup

  • ECG
  • BMP, Mg, Phos

Diagnosis

Classic torsades in 12-lead
Torsades de Pointes (TdP) in patient with a potassium of 2.4 mmol/L and a magnesium of 1.6mg/dL.
  • ECG showing the QRS complexes “twisting” around the isoelectric line

Management

Increasing HR decreases QT interval

  1. Magnesium sulfate - decreases calcium influx
    • 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
      • Danger of hypermagnesemia → depressed neuromuscular function and respiratory drive, so monitor closely
      • Supplement with K+
  2. Isoproterenol - Increases HR / AV conduction
    • 2-8 mcg/min
    • Target HR > 90 bpm
  3. Overdrive Pacing - Atrial > Ventricular pacing
    • Goal HR 90-120
    • Note: Not a treatment for TdP, but useful in maintaining sinus rhythm
  4. Defibrillation / synchronized cardioversion - Patient in extremis
  5. AVOID amiodarone and procainamide, which may worsen prolonged QT
  6. Lidocaine (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes
    • Lidocaine 1 mg/kg bolus, followed by 0.5-4 mg/min, titrated to rhythm response[1]
    • Inpatient may monitor plasma lidocaine levels, with goal < 6 mcg/mL

Disposition

  • Admit

See Also

References

  1. Reachi B, Negrelli J, Hickman A, Beesley S, Osborn J (2019) Isoproterenol and Lidocaine for Recurrent Torsades de Pointes in a 32-year-old Pregnant Woman. Int J Crit Care Emerg Med 5:092.