In this episode, I’ll discuss the treatment of drug-induced Torsades.
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When responding to code blue, rapid response calls, and other medical emergencies, take the stairs instead of the elevator whenever possible. I discuss this and much more in my book A Pharmacist’s Guide to Inpatient Medical Emergencies.
Shout out to “Pharmacy Stephen” for leaving a review on my book at Amazon. Stephen wrote: A great read for pharmacists of all ages! I have been a critical care pharmacist for years and attended many codes. I still found lots of advice in this book that I plan to put into action! I particularly liked the advice on the pharmacist’s role in code blue and all of the little tips to help ensure patient safety. It’s a quick read and would be great required reading for residents.
Background
Torsades de Pointes, or polymorphic ventricular tachycardia is a rare but life-threatening arrhythmia. It can be the result of congenital or acquired (drug induced) long QT syndrome.
As pharmacists, we will spend a disproportionate amount of our time attempting to prevent drug-induced Torsades compared to the time we will spend treating it. In episode 12, I discussed how I evaluate drug interactions related to prolonged QTc interval and risk of Torsades.
Treatment
The best treatments for Torsades are electricity and magnesium, but the order and technique for these treatments depend on the state of the patient.
Hemodynamically unstable patients
If the patient is hemodynamically unstable or in cardiac arrest, immediate defibrillation should be performed. This should be followed by 2 grams of magnesium sulfate IV push over 1-2 minutes.
Hemodynamically stable patients
If the patient is hemodynamically stable, or if they are conscious, magnesium sulfate is given first. The dose of magnesium sulfate is 2 grams over 15 minutes. A slower infusion rate is indicated because the rapid infusion of magnesium in a patient with a pulse, may result in severe hypotension or asystolic arrest. This dose of magnesium can be delivered by infusing a 2 gram in 50 mL minibag at a rate of 200 mL/hr.
Magnesium is effective in the treatment of Torsades even if the patient does not have a low magnesium level.
If magnesium fails to work, electricity in the form of transvenous overdrive pacing to a rate of 100 beats per minute should be used next.
Isoproterenol
Another possible treatment for Torsades in the conscious patient who does not respond to magnesium is an isoproterenol infusion. Start the isoproterenol at 0.1 mcg/kg/min and titrate to 100 beats per minute. Remember that isoproterenol is only indicated in acquired/drug-induced long QT syndrome – not in congenital long QT syndrome.
Depending on where in the hospital the patient experiences Torsades, it will likely be faster to get transvenous pacing started than an isoproterenol infusion.
Special circumstances when other therapies are indicated
Quinidine
For Torsades that is the result of quinidine, sodium bicarbonate should be administered. Alkalinizing the serum with sodium bicarbonate will decrease the amount of quinidine that is active on the heart. Despite the broadly publicized recommendation to treat quinidine-associated Torsades with sodium bicarbonate, I cannot find a recommended dose. If I were to encounter such a patient I would probably give IV push sodium bicarbonate until the Torsades resolved, followed by a continuous infusion of 150 mEq sodium bicarbonate in a liter of D5W.
Sotalol
For Torsades that is the result of sotalol, hemodialysis should be considered, especially if Torsades persists despite standard therapy.
Correct modifiable risk factors
Simultaneous with treatment for Torsades, efforts should be made to correct modifiable risk factors for Torsades such as discontinuing the offending medications, and correcting hypokalemia and hypomagnesemia.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
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