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FACP. Colegio de médicos de Tarragona Nº 4305520 / fgcapriles@gmail.com




Monday, November 2, 2015

Torcida de la punta

ERCAST.ORG - November 2, 2015 By Rob Orman 
"Torsades de pointes is very bad. It easily degenerates into Ventricular Fibrillation (VF) and that’s sudden cardiac death. How many cases of torsades have you seen in your career? Are your ready for it when you see it? Let’s see, there’s magnesium…uh, and then I seem to recall that drug isoproterenol (that I’ve never used) and then..oh yeah…I’m supposed to do ‘OVERDRIVE pacing’. Got it. Ummm, how do you do overdrive pacing? How does it work? DOES it work?First. 
Let’s set the record straight: emergency doctors don’t do overdrive pacing. How do I know that? Because there is only one indication for “overdrive pacing” in the ED: torsades de pointes. But the rate of torsades is 150-250 BPM. And the most commonly used pacemaker in US ED’s is the Medtronic single-chamber Pacer, which has a maximum RATE of 180 BPM. So how were you planning to OVERDRIVE Torsades, which is running at 250 BPM, when your max pacer rate is 180? See? You can’t even DO overdrive pacing. What are you really supposed to do?

Treatment of Torsades
  1. Stabilize the cardiac myocyte and treat hypomagnesemia: Magnesium 2gm IV q15m
  2. Increase the resting heart rate. Increasing the HR narrows the QT. Narrowing the QT narrows the T wave (ventricular repolarization). A narrow T wave means your ventricle is spending less time repolarizing. If your T wave is narrow, the chances of throwing a PVC on top of a T (R on T) is much less likely. So….just increase the heart rate. Oh wait…increase the heart rate AFTER you’ve cardioverted them from polymorphic VT.
Drugs to use after sinus rhythm achieved and you want to speed the heart rate
  • Isoproterenol
    • nonselective beta agonist
    • Inotropic, chronotropic, dromotropic
    • dose: 10-20 mcg IVP or drip
  • Epinephrine
  • Dopamine drip