In the interesting article by Viskin et al., adenosine-induced bradycardia was found to produce a higher increase in QT and a lower decrease in QTc (calculated using the Bazett formula) in subjects with long-QT syndrome (LQTS) than in controls. However, a major issue in this study concerns the reliability of QT correction when large ranges of heart rates are analysed. The Bazett formula overcor...

Long QT syndrome is characterized by prolongation of the corrected QT (QTc) interval on the surface electrocardiogram and is associated with precipitation of torsade de pointes (TdP), a polymorphic ventricular tachycardia that may cause sudden death. Acquired long QT syndrome describes pathologic excessive prolongation of the QT interval, upon exposure to an environmental stressor, with reversi...

The ability to recognize many tags simultaneously is crucial for many advanced RFID-based applications. The tag anti-collision algorithm of an RFID system, which arbitrates collisions on the air interface among tags in the same reading range of a reader, makes a great influence on the speed and the reliability in multiple tag recognition. This paper presents a new memoryless tag anti-collision ...

BACKGROUND   LQT1 subtype of long QT syndrome is characterized by defective I(Ks) , which is intrinsically stronger in the epicardium than in the midmyocardial region. Electrocardiographic QT peak and QT end intervals may reflect complete repolarization of epicardium and midmyocardial region of the ventricular wall, respectively. Repolarization abnormalities in LQT1 carriers may therefore be mo...

Cardiac risk factors are observed more frequently in patients with polycystic ovary syndrome (PCOS). On the other hand, increased QT dispersion, which is a risk factor for cardiac arrhythmias and sudden death, has not been investigated in this syndrome. In this study, we evaluated QT dispersion in PCOS patients without overt heart disease. Thirty-six consecutive women with PCOS (mean age 24+/-5...

AIMS The identification of affected family members with long QT syndrome (LQTS) is often difficult due to their normal-or only marginally lengthened-QT interval duration. We examined whether physical exercise test could increase the ability to detect the mutation carrier status in phenotypically normal LQTS family members. METHODS AND RESULTS Sixty-six subjects were included: 15 were carriers...

Objective—To determine the normal values of QT and QTc dispersion and the eVects of sinus arrhythmia on QT dispersion in healthy children. Patients and setting—The study was carried out in a university hospital on 372 local schoolchildren (200 male, 172 female), aged seven to 18 years. Methods—The QT and preceding RR intervals of at least one sinus beat were measured manually in a range of nine...

Among childhood psychiatric disorders, attention deficit hyperactivity disorder (ADHD) is of greatest interest to practitioners. Methylphenidate (MPH) is a drug that is widely used in the treatment of children in whom ADHD has been diagnosed. Although this treatment has been used for years, its effects on the heart remain the subject of debate. The QT interval comprises the ventricular activati...

Clinicians are well aware that responses to QT-prolonging drugs vary among individuals.1 A drug dose (and concentration) that produces minimal QT prolongation in one patient may, in an apparently indistinguishable subject, produce marked QT prolongation and torsade de pointes. This variability in response to an exogenous stressor is paralleled by variability in the extent to which a given mutat...