Difference between revisions of "Torsades de pointes"

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(Management)
 
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==Background==
 
==Background==
Drugs that inhibit P450
+
*Form of polymorphic [[VTach]]
#erythromycin
+
**Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
#biaxin
+
*Associated with congenital or acquired [[prolonged QT]]
#ketoconozole
 
#itraconozole
 
  
*certain antihistamines like terfandadine or astemizole, inhibit the delayed rectifier potassium channel
+
===Common Causes===
*terfenadine is completely metabolized in liver. Once metabolized, has no cardiac activity
+
'''POINTES''' mnemonic:
*unmetabolized terfenadine has quinidine- like activity- gives torsades
+
*[[Phenothiazines|'''P'''henothiazines]]
*if P450 enz inhibited by other drug, then will have increase in concentration of unmetabolized terfanadine.
+
*'''O'''ther medications (ie [[TCAs]])
 +
*[[ICH|'''I'''ntracranial bleed]]
 +
*'''N'''o known cause (idiopathic)
 +
*'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide)
 +
*[[electrolyte Abnormality|'''E'''lectrolyte abnormalities]] ([[hypokalemia|hypoK]] & [[hypomagnesemia|hypoMg]])
 +
*'''S'''yndrome of [[Prolonged QT]] (aka Long QT Syndrome)
 +
*Other causes:
 +
**[[Organophosphate toxicity]]
 +
**[[Hydrocarbon toxicity]]
 +
**[[Chloral hydrate toxicity]]
 +
**[[Hypothermia]]
  
==Treatment==
+
==Clinical Features==
#Mg (1-2gm over 1-2 minutes; then, 1-2gm/hr gtt)
+
*[[Syncope]]
#Overdrive pacing (hr = 90-120)
+
*[[Dizziness]], lightheadedness
#Isoproterenol (if no pacing, 2-8 mcg/min)
+
*[[Palpitations]]
#lidocaine
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*Sudden [[cardiac arrest]]
 +
 
 +
==Differential Diagnosis==
 +
*Drug induced
 +
*Congenital long QT
 +
*[[Hypocalcemia]]
 +
*[[Hypomagnesemia]]
 +
*[[Hypokalemia]]
 +
*[[Hypothermia]]
 +
*POINTES as above
 +
 
 +
{{Tachycardia (wide) DDX}}
 +
 
 +
==Evaluation==
 +
===Workup===
 +
*[[ECG]]
 +
*BMP, Mg, Phos
 +
 
 +
===Diagnosis===
 +
[[File:12leadTorsade.jpg|thumb|Classic torsades in 12-lead]]
 +
[[File:Torsades de Pointes TdP.png|thumb|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
 +
#[[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+
 +
#[[Isoproterenol]] - Increases HR / AV conduction
 +
#*2-8 mcg/min
 +
#*Target HR > 90 bpm
 +
#[[Overdrive Pacing]] - Atrial > Ventricular pacing
 +
#*Goal HR 90-120
 +
#*Note: Not a treatment for TdP, but useful in maintaining sinus rhythm
 +
#[[Defibrillation]] / [[synchronized cardioversion]] - Patient in extremis
 +
#'''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 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==
 +
*Admit
  
 
==See Also==
 
==See Also==
 
*[[Tachycardia (Wide)]]
 
*[[Tachycardia (Wide)]]
*[[ACLS Guidelines (2010)]]
+
*[[ACLS (2010 Guidelines)]]
  
==Source ==
+
==References==
10/07 DONALDSON (adapted from Tintinalli, Lampe)
+
<references/>
  
[[Category:Cards]]
+
[[Category:Cardiology]]

Latest revision as of 17:38, 1 July 2020

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

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.