Changes of the corrected QT interval in healthy boys and girls over day and night

Krasemann T, Strompen C, Blumenberg J, Gehrmann J, Burkhardtsmaier G, Vogt J

Abstract

AIMS: The study was designed to detect changes in corrected QT intervals over day and night in both sexes in healthy children. METHODS AND RESULTS: The corrected QT interval was calculated from 24 h ECGs obtained from 282 healthy children aged 6 months to 18 years. The QTc interval as measured by the 24 h recording differs to the standard ECG measurement which is in average of 40-50 ms shorter. The QTc interval changes little over a 24 h period and is remarkably constant despite significant heart rate changes in healthy children. CONCLUSION: The routine ECG-even if the calculated values differ markedly from those obtained over 24 h-seems to be a good screening method for the measurement of corrected QT intervals, because the corrected QT interval is kept constant over the whole day in healthy children.