Torsades de pointes: Difference between revisions
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==Background== | ==Background== | ||
* | *Form of polymorphic VTach | ||
*Associated with [[prolonged QT]] | **Gradual change in the amplitude of QRS complexes and twisting around isoelectric line | ||
*Associated with congenital or acquired [[prolonged QT]] | |||
===Common Causes=== | ===Common Causes=== | ||
| Line 15: | Line 16: | ||
==Clinical Features== | ==Clinical Features== | ||
*Syncope | *Syncope | ||
*Dizziness | |||
*Lightheadedness | |||
*Palpitations | |||
*Sudden Cardiac Death | |||
* | |||
* | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
| Line 30: | Line 29: | ||
*Hypothermia | *Hypothermia | ||
*POINTES as above | *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== | ==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) | #*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, so monitor closely | #**Danger of [[hypermagnesemia]] → depressed neuromuscular function and respiratory drive, so monitor closely | ||
#**Supplement with K+ | #**Supplement with K+ | ||
#[[Isoproterenol]] - Increases HR / AV conduction | #[[Isoproterenol]] - Increases HR / AV conduction | ||
| Line 42: | Line 53: | ||
#[[Overdrive Pacing]] - Atrial > Ventricular pacing | #[[Overdrive Pacing]] - Atrial > Ventricular pacing | ||
#*Goal HR 90-120 | #*Goal HR 90-120 | ||
#*Note: Not a treatment for TdP, but useful in maintaining sinus rhythm | |||
#[[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. | |||
==Disposition== | |||
*Admit | |||
==See Also== | ==See Also== | ||
Revision as of 06:45, 5 April 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:
- Phenothiazines
- Other medications (ie TCAs)
- Intracranial bleed
- No known cause (idiopathic)
- Type I anti-arrhythmics (quinidine, procainamide, disopyramide)
- Electrolyte abnormalities (hypoK & hypoMag)
- Syndrome of Prolonged QT (aka Long QT Syndrome)
Clinical Features
- Syncope
- Dizziness
- Lightheadedness
- Palpitations
- Sudden Cardiac Death
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.
Disposition
- Admit