QT-RR hysteresis is characterized by longer QT intervals at a given RR interval while heart rates are increasing during exercise and shorter QT intervals at the same RR interval while heart rates are decreasing during recovery. It has been attributed to a lagging QT response to different directional changes in RR interval during exercise and recovery. Twenty control subjects (8 males, age 51 ± ...

BACKGROUND Familial Mediterranean fever (FMF) is a chronic, recurrent auto-inflammatory disease characterised by self-terminating attacks of fever and sterile polyserositis. The main cause of death in auto-inflammatory diseases is cardiovascular events. Additionally, auto-inflammatory diseases have potential effects on the myocardial repolarisation parameters, including the T-wave peak-to-end (...

AIMS Women have a longer QT interval and a greater incidence of torsades de pointes than men. It has been suggested that oestrogens may influence the duration of cardiac repolarization. We thus investigated the influence of oestradiol (E2) on ventricular repolarization within the physiological concentration range of this hormone. METHODS AND RESULTS We studied QT interval duration in 21 healt...

1. QT variability is a non-invasive marker of cardiac repolarization lability and a higher QT variability is associated with sudden death. No data exist as to the circadian fluctuations in QT variability and the QT variability index (QTvi) in the canine. The purpose of the present investigation was to explore QT interval variability over 24 h in the healthy dog. 2. Continuous lead II electrocar...

One of the major reasons of drug withdrawal or drug label revision is the drug induced sudden cardiac death associated with a prolongation of the QT interval in the electrocardiogram (ECG). When the QT interval is prolonged, there is an increased risk of ventricular tachyarrhythmia, including the life threatening form torsade de pointes. The QT interval of the ECG is a measure of the duration o...

BACKGROUND Numerous structurally unrelated drugs, including antipsychotics, can prolong QT interval and trigger the acquired long QT syndrome (aLQTS). All of them are thought to act at the level of KCNH2, a subunit of the potassium channel. Although the QT-prolonging drugs are proscribed in the subjects with aLQTS, the individual response to diverse QT-prolonging drugs may vary substantially. ...

Common Cause of Short QT Interval To the Editor: I read with interest the recent report by Gaita et al1 of short-QT syndrome as a familial cause of sudden death. The authors enumerated other factors that shorten QT interval, such as increased heart rate, hyperthermia, hypercalcemia, hyperkalemia, acidosis, and altered autonomic tone.1 I would like to add another important and common, but undera...

OBJECTIVES Exercise-induced QT/RR hysteresis exists when, for a given R-R interval, the QT interval duration is shorter during recovery after exercise than during exercise. We sought to assess the association between QT/RR hysteresis and imaging evidence of myocardial ischemia. BACKGROUND Because ischemia induces cellular disturbances known to decrease membrane action potential duration, we h...

background : methadone is considered as a good choice for maintenance treatment program (mmtp) in opioid addicted individuals. qt interval prolongation was reported previously in methadone chronic usersespecially in high dose prescription. qt-interval prolongation predisposes patients to lethal dysrhythmia. this is a report of corrected qt(qtc) prolongation due to acute methadone poisoning. to ...

We examined the relationship between changes in heart rate and the measured QT interval of the electrocardiogram in healthy subjects after exercise and during breath holding, hyperventilation, the dive reflex, the Valsalva maneuver, and the cold-pressor test. The tachycardia of exercise was accompanied by the familiar shortening of the QT interval, but substantial heart rate changes encountered...