From the Guidelines
Yes, torsade de pointes is a polymorphic wide complex tachycardia characterized by QRS complexes that appear to twist around the baseline, giving it the French name meaning "twisting of the points." This dangerous arrhythmia typically occurs in the setting of a prolonged QT interval and can degenerate into ventricular fibrillation if not promptly addressed. Torsade de pointes is often triggered by medications that prolong the QT interval (such as certain antiarrhythmics, antipsychotics, antibiotics, and antiemetics), electrolyte abnormalities (particularly hypokalemia, hypomagnesemia), bradycardia, or congenital long QT syndromes. Immediate management includes discontinuation of QT-prolonging medications, correction of electrolyte abnormalities (especially giving IV magnesium sulfate 1-2g over 5-15 minutes), and in some cases, temporary overdrive pacing or isoproterenol to increase heart rate, as supported by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. The use of magnesium sulfate in the treatment of torsades de pointes is also supported by observational studies, which showed that IV magnesium sulfate can facilitate termination of torsades de pointes (irregular/polymorphic VT associated with prolonged QT interval) 1. Some key points to consider in the management of torsades de pointes include:
- Discontinuation of QT-prolonging medications
- Correction of electrolyte abnormalities, particularly hypokalemia and hypomagnesemia
- Administration of IV magnesium sulfate 1-2g over 5-15 minutes
- Temporary overdrive pacing or isoproterenol to increase heart rate in some cases
- Avoidance of isoproterenol in patients with familial long QT syndrome. Unlike monomorphic ventricular tachycardia, torsade de pointes has QRS complexes that continuously change in amplitude and morphology, creating its distinctive pattern on ECG. The management of torsades de pointes should be guided by the underlying cause of the arrhythmia and the presence or absence of a long QT interval during sinus rhythm, as outlined in the 2010 American Heart Association guidelines 1.
From the Research
Definition and Characteristics of Torsades de Pointes
- Torsades de pointes (TdP) is defined as a characteristic polymorphic ventricular arrhythmia associated with delayed ventricular repolarization, as evidenced by QT interval prolongation on the surface electrocardiogram 2, 3, 4, 5, 6.
- It is characterized by a specific, polymorphic but organized ventricular activation on the surface electrocardiogram, constituting episodes of rapid tachycardia that are usually short-lasting and terminate spontaneously 3, 4.
- TdP is a form of polymorphic ventricular tachycardia with a particular electrocardiographic pattern of continuously changing ("twisting") morphology of the QRS complex, occurring in the setting of delayed myocardial repolarization (i.e., prolongation of the QT interval) 4, 5, 6.
Relationship between TdP and Wide Complex Tachycardia
- TdP is indeed a polymorphic wide complex tachycardia, as it is characterized by a wide QRS complex and a rapid, irregular heart rate 2, 3, 4, 5, 6.
- The polymorphic nature of TdP refers to the changing morphology of the QRS complex, which is a hallmark of this arrhythmia 3, 4.
Clinical Implications and Treatment
- TdP is a potentially life-threatening arrhythmia that requires prompt recognition and treatment, as it can progress to ventricular fibrillation and sudden death 2, 3, 5, 6.
- Treatment of TdP typically involves removal or correction of precipitants, such as discontinuation of culprit drugs, correction of electrolyte abnormalities, and institution of cardiac monitoring 2, 3, 5, 6.