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The pause that refreshes, or does it? Mechanisms in torsades de pointes
  1. Departments of Medicine and Pharmacology
  2. Vanderbilt University School of Medicine
  3. 532 Medical Research Building - I
  4. Nashville, TN 37232–6602
  5. USA
  6. email:

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Dessertenne, who coined the term “torsades de pointes”, was one of the first to draw attention to the association of long QT related arrhythmia (commonly caused by heart block or drugs) and underlying bradycardia.1 Indeed, the “short-long-short” series of cycles before torsade de pointes is so characteristic of acquired “long QT syndrome” (LQTS) that lack of a “pause” before onset calls into question the diagnosis.2 ,3 Some features of the congenital LQTS are very similar to those in the acquired form. These include a preponderance of women among patients who are symptomatic with syncope or sudden death, and the possible potentiating role of hypokalaemia in the genesis of the arrhythmia. Indeed, extraordinary advances in our understanding of the molecular basis of the congenital and acquired syndromes now point to common mechanisms that underlie these two closely related entities.4 ,5 However, despite considerable attention to the electrocardiographic features of these diseases, it is not known whether the onset of the arrhythmia in the congenital form is pause dependent as in the acquired form. In a recent issue of Heart, Visken and colleagues summarised the electrocardiographic features at onset of torsade de pointes in patients with the congenital form of the syndrome.6 Their findings—that not all episodes are pause dependent—provide intriguing new data for investigators interested in linking the clinical and molecular events involved in genesis of long QT related arrhythmias.

Mutations causing the congenital LQTS

Congenital LQTS remained an electrophysiologic curiosity until 1995 and 1996, when Keating and colleagues linked the syndrome to mutations in the genes encoding ion channel proteins. These findings have had important implications for our understanding not only of arrhythmia mechanisms in this obscure but interesting disease, but also in further understanding the concept of dysregulated expression or function of these proteins as a proximate …

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