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. 2000 Jun;83(6):661–666. doi: 10.1136/heart.83.6.661

Arrhythmias in the congenital long QT syndrome: how often is torsade de pointes pause dependent?

S Viskin 1, R Fish 1, D Zeltser 1, B Belhassen 1, K Heller 1, D Brosh 1, S Laniado 1, H Barron 1
PMCID: PMC1760887  PMID: 10814624

Abstract

OBJECTIVE—To determine the frequency and predictors of pause dependent torsade de pointes among patients with the congenital long QT syndrome and spontaneous ventricular tachyarrhythmias.
DESIGN—The literature on the "congenital long QT" was reviewed. Articles with illustrations demonstrating the onset of spontaneous polymorphic ventricular arrhythmias in the absence of arrhythmogenic drugs were included.
RESULTS—Illustrations of 62 spontaneous episodes of torsade de pointes among patients with congenital long QT syndrome were found in the literature. The majority (74%) of documented arrhythmias were "pause dependent"; 82% of these pauses were longer than the basic cycle length by > 100 ms. Age and sex correlated with the mode of arrhythmia initiation. Arrhythmias in infants (⩽ 3 years old) were not pause dependent, while female sex correlated with pause dependent torsade. Using multivariate analysis, age was the only independent predictor of the mode of onset of torsade de pointes.
CONCLUSION—Available data suggest that the majority of spontaneous arrhythmias in the congenital long QT syndrome are pause dependent. Torsade de pointes that is not preceded by pauses appears to be limited to patient subgroups with severe forms of the disease, like symptomatic infants. These findings have important implications regarding the use of cardiac pacing for arrhythmia prevention.


Keywords: long QT; congenital long QT syndrome; torsade de pointes; ventricular tachycardia

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Figure 1  .

Figure 1  

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Spontaneous torsade de pointes in a 25 year old female with congenital LQTS reported by Benhorin and Medina.46 This Holter recording shows the sequence of events that is typical of pause dependent torsade de pointes. Sinus tachycardia is followed by a sudden decrement in sinus rate (A) with concomitant augmentation of the U wave amplitude (arrow). Eventually, an extrasystole (arrowhead) is followed by a long post-extrasystolic pause. The sinus complex that follows the pause shows further U wave augmentation and is followed by more extrasystoles (arrowhead), which in turn, trigger a new pause. This creates a series of short (s) and long (l) cycles that culminate in torsade de pointes. Reproduced with permission from the authors and the Massachusetts Medical Society (copyright© 1997 Massachusetts Medical Society).

Figure 2  .

Figure 2  

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The top trace shows what is probably the most famous example of non-pause dependent torsade de pointes. It was originally published by Malfatto and colleagues36 and is commonly cited as a typical example of adrenergic dependent torsade de pointes.45 The preceding sinus rate is 90 beats per minute and there is no pause before the onset of the arrhythmia. This 11 year old female patient also had documented pause dependent torsade de pointes (middle and bottom panels): Sudden sinus pauses (*) are followed by sinus complexes with tall bizarre TU waves (arrows) from which short bursts of torsade de pointes originate. Reproduced with permission from the authors and Futura Publishing Company Inc, publisher of the Journal of Cardiovascular Electrophysiology.

Figure 3  .

Figure 3  

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R-R intervals preceding the onset of arrhythmias in patients with pause dependent torsade de pointes. BCL, basic cycle length; short and long, short cycle and long cycle immediately preceding the onset of torsade.

Figure 4  .

Figure 4  

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(A) Non-pause dependent torsade de pointes in a neonate.47 There is sinus tachycardia with marked T wave alternans. Although there appears to be some R-R alternans (the R-R intervals are shown in milliseconds), the interval immediately preceding the sinus complex from which torsade originates, which would be expected to be the longest interval if this was a pause dependent arrhythmia (*), is actually short (420 ms). Reproduced with permission from the authors and Futura Publishing Company Inc, publisher of the Journal of Cardiovascular Electrophysiology. (B) One of the first cases of congenital long QT syndrome and deafness described.16 The QT interval is giant and bizarre. Torsade de pointes is not preceded by a pause. Reproduced with permission from Mosby Inc, publisher of Advances in Internal Medicine.

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