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]] | ||
| Line 6: | Line 6: | ||
===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 | + | *'''T'''ype I [[antiarrhythmics]] ([[quinidine]], [[procainamide]], disopyramide) |
| − | *'''E'''lectrolyte abnormalities (hypoK & | + | *[[electrolyte Abnormality|'''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 |
| − | * | + | *[[Palpitations]] |
| − | + | *Sudden [[cardiac arrest]] | |
| − | *Sudden | ||
==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 | ||
| Line 56: | Line 60: | ||
#[[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== | ||
Latest revision as of 17:38, 1 July 2020
Contents
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:
- Phenothiazines
- Other medications (ie TCAs)
- Intracranial bleed
- No known cause (idiopathic)
- Type I antiarrhythmics (quinidine, procainamide, disopyramide)
- Electrolyte abnormalities (hypoK & hypoMg)
- Syndrome of Prolonged QT (aka Long QT Syndrome)
- Other causes:
Clinical Features
- Syncope
- Dizziness, lightheadedness
- Palpitations
- Sudden cardiac arrest
Differential Diagnosis
- Drug induced
- Congenital long QT
- Hypocalcemia
- Hypomagnesemia
- Hypokalemia
- Hypothermia
- POINTES as above
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)
- Regular
- Monomorphic ventricular tachycardia
- PSVT with aberrant conduction:
- PSVT with bundle branch block^
- PSVT with accessory pathway
- Atrial flutter with bundle branch block^
- Sinus tachycardia with bundle branch block^
- Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
- Metabolic
- Irregular
- Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
- Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
- Atrial fibrillation + hyperkalemia
- Polymorphic ventricular tachycardia
^Fixed or rate-related
Evaluation
Workup
- ECG
- BMP, Mg, Phos
Diagnosis
- 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+
- 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
- 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[1]
- Inpatient may monitor plasma lidocaine levels, with goal < 6 mcg/mL
Disposition
- Admit
See Also
References
- ↑ 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.