Difference between revisions of "Torsades de pointes"

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==Background==
 
==Background==
*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]]
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===Common Causes===
 
===Common Causes===
 
'''POINTES''' mnemonic:
 
'''POINTES''' mnemonic:
*'''P'''henothiazines
+
*'[[Phenothiazines|''P'''henothiazines]]
*'''O'''ther medications (ie TCAs)
+
*'''O'''ther medications (ie [[TCAs]])
*'''I'''ntracranial bleed
+
*'[[ICH|''I'''ntracranial bleed]]
 
*'''N'''o known cause (idiopathic)
 
*'''N'''o known cause (idiopathic)
*'''T'''ype I anti-arrhythmics (quinidine, procainamide, disopyramide)
+
*'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide)
*'''E'''lectrolyte abnormalities (hypoK & hypoMag)
+
*[[electrolyte disorders|'''E'''lectrolyte abnormalities]] ([[hypokalemia|hypoK]] & [[hypomagnesemia|hypoMg]])
*'''S'''yndrome of Prolonged QT (aka Long QT Syndrome)
+
*'''S'''yndrome of [[Prolonged QT]] (aka Long QT Syndrome)
 +
*Other causes:
 +
**[[Organophosphate toxicity]]
 +
**[[Hydrocarbon toxicity]]
 +
**[[Chloral hydrate toxicity]]
 +
**[[Hypothermia]]
  
 
==Clinical Features==
 
==Clinical Features==
*Syncope
+
*[[Syncope]]
*Dizziness
+
*[[Dizziness]], lightheadedness
*Lightheadedness
+
*[[Palpitations]]
*Palpitations
+
*Sudden [[cardiac arrest]]
*Sudden Cardiac Death
 
  
 
==Differential Diagnosis==
 
==Differential Diagnosis==
 
*Drug induced
 
*Drug induced
 
*Congenital long QT
 
*Congenital long QT
*Hypocalcemia
+
*[[Hypocalcemia]]
*Hypomagnesemia
+
*[[Hypomagnesemia]]
*Hypokalemia
+
*[[Hypokalemia]]
*Hypothermia
+
*[[Hypothermia]]
 
*POINTES as above
 
*POINTES as above
  

Revision as of 18:28, 26 September 2019

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.

Disposition

  • Admit

See Also

References