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Encyclopedia > Torsades de pointes

Torsades de pointes or torsades is a French term that literally means "twisting of the points". It refers to a specific variety of ventricular tachycardia and its name is derived from a maneuver in ballet. On the electrocardiogram, torsades is irregular, polymorphic, and often exhibits a "streamer" effect as the QRS complex transitions from positive to negative, and back again. Clinically speaking, the difference between polymorphic ventricular tachycardia and torsades de pointes is the presence of a prolonged QT interval in the underlying rhythm of the latter. Ventricular tachycardia (V-tach or VT) is a fast rhythm that originates in one of the ventricles of the heart. ... “QRS” redirects here. ... The QRS complex is a record of the measurement of the movement of electrical impulses through the lower heart chambers (ventricles). ... Schematic representation of normal ECG trace (sinus rhythm), with waves, segments, and intervals labeled. ...

Contents

Causes

Common causes for torsades de pointes include hypomagnesemia (not enough magnesium) and hypokalemia (not enough potassium). It is commonly seen in malnourished individuals and chronic alcoholics. Drug interactions such as erythromycin taken concomitantly with inhibitors like nitroimidazole, Diarrhea, dietary supplements, and various medications, including tricyclic antidepressants and phenothiazines, may also contribute. Hypomagnesemia is an electrolyte disturbance in which there is an abnormally low level of magnesium in the blood. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Standard atomic weight 24. ... Hypokalemia is a potentially fatal condition in which the body fails to retain sufficient potassium to maintain health. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Standard atomic weight 39. ... Alcoholism is the consumption of, or preoccupation with, alcoholic beverages to the extent that this behavior interferes with the drinkers normal personal, family, social, or work life, and may lead to physical or mental harm. ... Types 5-7 on the Bristol Stool Chart are often associated with diarrhea Diarrhea (in American English) or diarrhoea (in British English) is a generally unpleasant condition in which the sufferer has frequent watery, loose bowel movements (from the Greek word διάρροια; literally meaning through-flowing). Acute infectious diarrhea is a... Chemical structure of the tricyclic antidepressant amitriptyline Tricyclic antidepressants are a class of antidepressant drugs first used in the 1950s. ... Phenothiazines are the largest of the 5 main classes of antipsychotic drugs. ...


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

The long QT syndrome (LQTS) is a heart condition in which there is an abnormally long delay between the electrical excitation (or depolarization) and relaxation (repolarization) of the ventricles of the heart. ... Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress fast rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. ... Hypomagnesemia is an electrolyte disturbance in which there is an abnormally low level of magnesium in the blood. ... Hypokalemia is a potentially fatal condition in which the body fails to retain sufficient potassium to maintain health. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... Acidosis is an increased acidity (i. ... Left ventricular hypertrophy (LVH) is the abnormal thickening of the myocardium (muscle) of the left ventricle of the heart. ... Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min [1]. It is also less commonly known as brachycardia. ...

Treatment

Treatment is directed at withdrawal of the offending agent, infusion of magnesium sulfate, antiarrhythmic drugs, and electrical therapy as needed. Because of the polymorphic nature of torsades de pointes, synchronized cardioversion may not be possible, and the patient may require an unsynchronized shock (or defibrillation). Magnesium sulfate is a chemical compound containing magnesium, with the formula MgSO4. ... Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress fast rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. ... Through electricity or drug therapy, cardioversion converts heart arrhythmias to normal rhythms. ... Typical view of the defibrillator operator. ...


History and 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. A medical journal is a scientific journal devoted to the field of medicine. ... There are very few or no other articles that link to this one. ... 1966 (MCMLXVI) was a common year starting on Saturday (the link is to a full 1966 calendar). ... Atrioventricular (having to do with an atrium and ventricle) can refer to: Left atrioventricular opening Atrioventricular (rock band) Atrioventricular fistula Atrioventricular node The term Atrioventricular valves is used to describe the mitral valve and tricuspid valve. ...


References

  • Dessertenne F. Ventricular tachycardia with two variable opposing foci. Arch Mal Coeur Vaiss 1966;59:263-72. PMID 4956181.

  Results from FactBites:
 
Torsades de Pointes in Patients Receiving Terfenadine or Astemizole. (2238 words)
Torsades de pointes is a form of polymorphic ventricular tachycardia that is preceded by a prolongation of the QT interval (Monahan et al, 1990).
Torsades de pointes occurred in one patient whose daily dosage had been increased steadily over six weeks to 360 mg daily; this was the first reported case of torsades de pointes caused by an enhanced therapeutic dose of terfenadine in isolation (MacConnell and Stanners, 1991).
Torsades de pointes occurring in association with terfenadine use.
  More results at FactBites »

 
 

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