Corrected QT interval in white young healthy women: should the norms be updated?

The electrocardiographic QT interval duration is a frequently studied ECG parameter. The aim of this study was to compare the quantitative influence of nine QTc formulae and discuss the duration of QT/QTc normal values. The QTc duration was calculated from manually measured QT intervals and heart rate of the Frank XYZ electrocardiograms in 138 white young healthy Slovak women (18-24 years, 690 primary ECG measurements).

Comparison and recalculation of the very different QTc interval durations in young healthy women.

Unlabelled: The aim was to use some simple way for easier comparison, other expression or recalculation of the QTc duration from one formula to another in order to remove the large QTc differences.

Methods And Results: The QT interval duration in 138 young healthy women was taken from our archive. The measured QT interval was corrected for heart rate (QTc) according to nine published regression equations (Bazett, Fridericia, Hodges, Sarma, Lecocq, Rautaharju, Sagie=Framingham, Arrowood, Malik) and compared mathematically by the Pearson correlation coefficient R and graphically by linear correlation.

Circa(ultra)dians of single extrasystoles in chronic respiratory failure versus health at lowland.

Background: The circa- and ultradians of the single extrasystoles' frequency in patients with chronic respiratory insufficiency (CRI) in lowlands (Kosice 210 m) were studied by the testing of following null hypotheses: their average frequency as well as rhythmicity is the same as at health.

Methods: In 54 elderly males with CRI, mean numbers of supraventricular (SV) and ventricular (VE) extrasystoles were calculated for each 24 hours. The Halberg cosinor regression was used to test the presence of the 24-hour rhythm and its 2nd to 10th harmonics, i.

Circadian and ultradian extrasystole rhythms in healthy individuals at elevated versus lowland altitudes.

We defined chronobiologic norms for supraventricular and ventricular single extrasystoles (SV and VE, respectively) in healthy older males in lowland areas. The study was extended to higher altitudes, where hypobaric hypoxia was expected to increase extrasystole frequency, while perhaps not changing rhythmicity. In healthy men (lowland n = 37, altitude n = 22), aged 49-72 years, mean numbers of SVs and VEs were counted over a 24-h period.

Effect of systemic hypoxia and reoxygenation on electrical stability of the rat myocardium: chronophysiological study.

The aim of the study was to determine the dependence of changes in the electrical stability of the heart on the light-dark cycle (LD cycle) in disorders of pulmonary ventilation. The ventricular arrhythmia threshold (VAT) was measured in female Wistar rats (adaptation to the light regime 12:12 h, ketamine/xylazine anesthesia 100 mg/15 mg/kg, i.m.