Torsades de pointes is a polymorphic ventricular tachycardia in which the QRS complexes seem to twist around the baseline, occurring on a background of a long QT interval. Common triggers are QT-prolonging drugs, low potassium or magnesium and slow heart rates, and it can turn into ventricular fibrillation.
Key symptoms
- Palpitations
- Lightheadedness or sudden fainting
- Seizure-like jerking during a long episode
- Sudden collapse
What you find on exam
- Check responsiveness and pulse first
- Fast pulse or no pulse during the episode
- Blood pressure and level of consciousness
- Full medication list: antiarrhythmics, methadone, haloperidol, ondansetron, some antibiotics
Tests
- Monitor or ECG: wide QRS complexes that twist in amplitude around the baseline
- Baseline ECG: long QTc, with risk high above 500 ms
- Magnesium, potassium and calcium
- Family history and genetic testing if congenital long QT is suspected
Treatment basics
- IV magnesium sulfate 2 g, even if the magnesium level is normal
- No pulse or unstable: unsynchronized defibrillation
- Stop all QT-prolonging drugs and raise potassium to at least 4
- Recurrent episodes: overdrive pacing or isoproterenol to speed the heart
- Congenital long QT: beta blocker and, in high-risk patients, an ICD
Red flags
- Fainting in a patient with a long QT
- QTc above 500 ms or rising after a new drug
- Rhythm that degenerates into ventricular fibrillation or loss of pulse
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Sources: AHA Guidelines for CPR and ECC; NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations. Written by Making Synapses. Making Synapses is not affiliated with these organizations.