Torsades de pointes
In medicine, torsades de pointes is a "malignant form of polymorphic ventricular tachycardia that is characterized by heart rate between 200 and 250 beats per minute, and QRS complexes with changing amplitude and twisting of the points. The term also describes the syndrome of tachycardia with prolonged ventricular repolarization, long QT intervals exceeding 500 milliseconds or bradycardia. Torsades de pointes may be self-limited or may progress to ventricular fibrillation."[1]
Causes/etiology
Torsades may be a type of drug toxicity caused by drugs that prolong the QT interval.[2] Prominent examples include methadone[3] and terfenadine[4][5]. A list of these drugs is available at the Arizona Center for Education & Research on Therapeutics.
Treatment
The initial treatment is magnesium according to the clinical practice guidelines for advanced cardiac life support by the American Heart Association:[6]
- "When VF/pulseless VT cardiac arrest is associated with torsades de pointes, providers may administer magnesium sulfate at a dose of 1 to 2 g diluted in 10 mL D5W IV/IO push, typically over 5 to 20 minutes."
- "When torsades is present in the patient with pulses, the same 1 to 2 g is mixed in 50 to 100 mL of D5W and given as a loading dose. It can be given more slowly (eg, over 5 to 60 minutes IV) under these conditions."
Prevention
Screen for prolonged QT interval[7] or inhibition of Ether-A-Go-Go potassium channels (ERG) channels[8] may help.
References
- ↑ Anonymous (2024), Torsades de pointes (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ Roden DM (March 2004). "Drug-induced prolongation of the QT interval". N. Engl. J. Med. 350 (10): 1013–22. DOI:10.1056/NEJMra032426. PMID 14999113. Research Blogging.
- ↑ Krantz MJ, Martin J, Stimmel B, Mehta D, Haigney MC (December 2008). "QTc Interval Screening in Methadone Treatment: the CSAT Consensus Guideline". Ann. Intern. Med.. PMID 19047020. [e]
- ↑ Monahan BP, Ferguson CL, Killeavy ES, Lloyd BK, Troy J, Cantilena LR (1990). "Torsades de pointes occurring in association with terfenadine use.". JAMA 264 (21): 2788-90. DOI:10.1001/jama.1990.03450210088038. PMID 1977935. Research Blogging.
- ↑ Woosley RL, Chen Y, Freiman JP, Gillis RA (1993 Mar 24-31). "Mechanism of the cardiotoxic actions of terfenadine.". JAMA 269 (12): 1532-6. DOI:10.1001/jama.1993.03500120070028. PMID 8445816. Research Blogging.
- ↑ (December 2005) "2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: Part 7.2: Management of Cardiac Arrest". Circulation 112 (24 Suppl): IV1–203. DOI:10.1161/CIRCULATIONAHA.105.166550. PMID 16314375. Research Blogging.
- ↑ Krantz MJ, Martin J, Stimmel B, Mehta D, Haigney MC (January 2009). "QTc Interval Screening in Methadone Treatment". Ann. Intern. Med.. PMID 19153406. [e]
- ↑ De Ponti F, Poluzzi E, Cavalli A, Recanatini M, Montanaro N (2002). "Safety of non-antiarrhythmic drugs that prolong the QT interval or induce torsade de pointes: an overview". Drug Saf 25 (4): 263–86. PMID 11994029. [e]
External links
- http://torsades.org - Arizona Center for Education & Research on Therapeutics