Torsades de pointes: Difference between revisions
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Revision as of 00:30, 28 June 2016
Background
- Torsades de Pointes is a form of polymorphic VTach, where there is a gradual change in the amplitude and twisting of the QRS complexes around the isoelectric line
- Associated with prolonged QT, which may be congenital or acquired.
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
Diagnosis
- ECG
- BMP, Mg, Phos
Differential Diagnosis
- Drug induced
- Congenital long QT
- Hypocalcemia
- Hypomagnesemia
- Hypokalemia
- Hypothermia
- POINTES as above
Treatment
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) gtt
- Danger of hypermagnesemia → depressed neuromuscular function, so monitor closely
- Supplement with K+
- 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) gtt
- Isoproterenol - Increases HR / AV conduction
- 2-8 mcg/min
- Target HR > 90 bpm
- Overdrive Pacing - Atrial > Ventricular pacing
- Goal HR 90-120
- Defibrillation / synchronized cardioversion - Patient in extremis
- AVOID amiodarone and procainamide, which may worsen prolonged QT