Torsade de pointes

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Torsade de pointes
DiseasesDB 29252
MeSH D016171

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List of terms related to Torsade de pointes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Overview

Torsade de pointes or torsades is a French term that literally means "twisting of the points" is a ventricular tachycardia associated with a long QT time on the resting ECG.

Torsade de pointes is typically initiated by a short-long-short interval. A ventricle extrasystole (first beat: short) is followed by a compensatory pause. The following beat (second beat: long) has a longer QT interval. If the next beat follows shortly thereafter, ther is a good chance that this third beat falls within the QT interval, resulting in the R on T phenomenon and subsequent Torsade de pointes. During Torsade de pointes the ventricles depolarize in a circular fashion resulting in QRS complexes with a continuously turning heart axis around the baseline (hence the name Torsade de Pointes). Read the chapter on the Long QT Syndrome for an list of causes.

Also, a more rare form of short coupled Torsade de pointes has been observed.[1]

Historical Perspective

It was first described by Dessertenne in 1966[2] and refers to a specific variety of ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG).

Terminology

The French term is largely due to the fact that the phenomenon was originally described in a French medical journal by Dessertenne in 1966, when he observed this rhythm disorder in an 80-year-old female patient with complete intermittent atrioventricular block.

There has been much debate in the Circulation journal among French and American scientist whether one should write Torsades de Pointes or Torsade de Pointes.

As for now Torsade is prefered (unless one sees rotations around more than one axis in one episode), but both forms are used in similar frequency.[3]

History and symptoms

Characteristic tracing showing the "twisting" (blue line) of Torsade de pointes

Torsades is a rapid, polymorphic ventricular tachycardia with a characteristic twist of the QRS complex around the isoelectric baseline. It is also associated with a fall in arterial blood pressure, which gives rise to the syncopal symptoms experienced by patients. Although torsade de pointes is a rare ventricular arrhythmia, it can degenerate into ventricular fibrillation, which will lead to sudden death in the absence of medical intervention. The common symptoms associated with it are as follows:

In young patients history of congenital long QT syndrome, congenital deafness (Jervell and Lange-Nielsen syndrome presenting with congenital sensorineural deafness and cardiac abnormalities), family history of sudden cardiac death should be asked. Also, medication history to rule out acquired causes of Torsade de pointes should be actively searched.

Physical examination

Physical examination findings depends on the rate and duration of the episode and the effect on cerebral perfusion during the episode. The physical finding may include:

Causes

Long QT syndrome can either be inherited as congenital mutations of ion channels carrying the cardiac impulse/action potential or acquired as a result of drugs that block these cardiac ion currents.

Common causes for torsades de pointes include hypomagnesemia and hypokalemia. It is commonly seen in malnourished individuals and chronic alcoholics. Drug interactions such as erythromycin or Avelox, taken concomitantly with inhibitors like nitroimidazole, Diarrhea, dietary supplements, and various medications like methadone, Lithium, tricyclic antidepressants or phenothiazines may also contribute.

Factors that are associated with an increased tendency toward torsades de pointes include:

The List of Drugs that Causing Torsades de pointes

Drugs that are generally accepted to have a risk of causing torsades de pointes

The List of Drugs that Possible Causing Torsades de pointes

Drugs that in some reports have been associated with torsades de pointes and/or QT prolongation but at this time lack substantial evidence for causing torsades de pointes.

The List of Drugs that Causing Torsades de pointes in Certain Conditions

Drugs that, in some reports, have been weakly associated with torsades de pointes and/or QT prolongation but that are unlikely to be a risk for torsades de pointes when used in usual recommended dosages and in patients without other risk factors (e.g., concomitant QT prolonging drugs, bradycardia, electrolyte disturbances, congenital long QT syndrome, concomitant drugs that inhibit metabolism)

Differential diagnosis

Characteristics

  • Rotation of the heart's electrical axis by at least 180º
  • Prolonged QT-interval LQTS
  • Preceded by long and short RR-intervals
  • Triggered by an early premature ventricular contraction(R-on-T PVC)

Treatment

Acute Treatment

If the episode of does not terminate on its own and degenerates into ventricular fibrillation, cardioversion is required.

Lead II electrocardiogram showing Torsades being shocked by an Implantable cardioverter-defibrillator back to the patients baseline cardiac rhythm.

Once the patient is back in normal sinus rhythm, a vigorous search for and correction of conditions that predispose to torsades de pointes which include hypokalemia, hypomagnesemia, and bradycardia should be made. Magnesium sulfate (1-2 g IV over 30-60 seconds) reduces the influx of calcium thereby lowering the amplitude of early after depolarizations and should also be infused even if the magnesium is normal. [4][5] Administration of lidocaine is generally not effective, but mexiletene may be helpful in suppressing the recurrence of torsade de pointes.

Additional Information

External Links

Torsade de Pointes related drug list

Examples

EKG's shown below are courtesy of C. Michael Gibson MS MD, and copylefted


Examples from different resources



References

  1. 1.0 1.1 1.2 1.3 1.4 Leenhardt A, Glaser E, Burguera M, Nuernberg M, Maison-Blanche P, and Coumel P. Short-coupled variant of torsade de pointes. A new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias. Circulation 1994 Jan; 89(1) 206-15. PMID 8281648
  2. Dessertenne F (1966). "[Ventricular tachycardia with 2 variable opposing foci]". Archives des maladies du coeur et des vaisseaux (in French). 59 (2): 263–72. PMID 4956181.
  3. Moise NS. As Americans, we should get this right. Circulation 1999 Sep 28; 100(13) 1462. PMID 10500317
  4. Hoshino K, Ogawa K, Hishitani T, Isobe T, Eto Y (2004). "Optimal administration dosage of magnesium sulfate for torsades de pointes in children with long QT syndrome". J Am Coll Nutr. 23 (5): 497S–500S. PMID 15466950. Unknown parameter |month= ignored (help)
  5. Hoshino K, Ogawa K, Hishitani T, Isobe T, Etoh Y (2006). "Successful uses of magnesium sulfate for torsades de pointes in children with long QT syndrome". Pediatr Int. 48 (2): 112–7. doi:10.1111/j.1442-200X.2006.02177.x. PMID 16635167. Unknown parameter |month= ignored (help)
  6. Khan IA. Twelve-lead electrocardiogram of torsade de pointes Tex Heart Inst J. 2001; 28 (1): 69. PMID 11330748

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