The dynamics and homogeneity of the QT interval have been used as indicators of susceptibility to ventricular arrhythmias. We determined the relationship between QT intervals and heart rate during exercise testing and subsequent recovery in 18 healthy children. The QT intervals were measured to the apex (early QT), to the end (total QT), and from the apex to the end of the T wave (late QT) (inh...

OBJECTIVES To improve the diagnostic criteria of the congenital long QT syndrome in borderline cases we examined rate adaptation of ventricular repolarization phases during exercise and subsequent recovery in children with the long QT syndrome and controls. METHODS Nineteen children with definite long QT syndrome and 19 healthy controls underwent exercise testing. QT intervals were measured t...

There has been an increasing focus on drug induced QT prolongation including research on drug development and QT prolongation, following the removal of drugs due to torsades de pointes (TdP). Although this has improved our understanding of drug-induced QT prolongation there has been much less research aimed at helping clinicians assess risk in individual patients with drug induced QT prolongati...

Torsade de points (TdP), a life-threatening arrhythmia that can increase the risk of sudden cardiac death, is associated with drug-induced QT-interval prolongation on electrocardiogram (ECG). While many modern ECG machines provide automated measurements QT-interval, these QT values are usually correct only for noise-free normal sinus rhythm, in which T-wave morphology well defined. As QT-prolon...

Homogeneity of recovery time protects against arrhythmias whereas dispersion of recovery time is arrhythmogenic. A single surface electrocardiographic QT interval gives no information on recovery time dispersion but the difference between the maximum and minimum body surface QT interval may be relevant. This hypothesis was tested by measuring the dispersion of the corrected QT interval (QTc) in...

We prove that a GF(q)-linear Rédei blocking set of size qt + qt−1 + · · · + q + 1 of PG(2, qt ) defines a derivable partial spread of PG(2t − 1, q). Using such a relationship, we are able to prove that there are at least two inequivalent Rédei minimal blocking sets of size qt + qt−1 + · · · + q + 1 in PG(2, qt ), if t ≥ 4.

Background: Breath holding spells (BHS) are paroxysmal events with apnea and postural tone with Electrocardiography (ECG) abnormality and epilepsy status reports. The study aimed to compare the ECG parameters’ in epilepsy and breath-holding children compared with healthy children. Materials and Methods: </st...

The dependence on heart rate of the QT interval has been investigated for many years and several mathematical formulae have been proposed to describe the QT interval/heart rate (or QT interval/RR interval) relationship. While the most popular is Bazett's formula, it overcorrects the QT interval at high heart rates and under-corrects it at slow heart rates. This formulae and many others similar ...

OBJECTIVE To study QT dispersion in left ventricular hypertrophy and chronic heart failure and to determine the relation to ventricular arrhythmias. SETTING Investigational laboratory of a tertiary referral centre. STUDY DESIGN Patients with left ventricular hypertrophy and normal systolic function (n = 14) and patients with chronic heart failure (n = 18) were matched with controls (n = 17)...