Beat-to-beat QT interval variability in children: normal and physiologic data.
BACKGROUND
QT interval variability provides information on ventricular vulnerability. However, QT interval variability in children has not been adequately evaluated.


METHODS
One hundred seventy-three consecutive nursing infants and children (male-female, 106:67) up to school age with no intrinsic cardiac disease were included in this study, and they were categorized into 6 age-related groups. The QT variability index (QTVI) was calculated based on an electrocardiogram; and age-specific standard values, sex-specific classification, and a standard growth curve covering 0 to 7 years were constructed.


RESULTS
The QTVI decreased in an age-dependent manner, reached constant values after school age, and exhibited no sex-specific differences in 6 age-related groups.


CONCLUSIONS
Based on the age-dependent standardized QTVI values, it is possible to estimate the instability of ventricular repolarization in pediatric patients with better accuracy.
Kusuki
Hirofumi
H
Clinical Laboratory, Mie University Hospital, Japan. hiro.kusuki@gmail.com
Kuriki
Marina
M
Horio
Kayo
K
Hosoi
Misa
M
Matsuura
Hideaki
H
Fujino
Masayuki
M
Eryu
Yoshihiko
Y
Miyata
Masafumi
M
Yasuda
Toshiaki
T
Yamazaki
Toshio
T
Nagaoka
Shunji
S
Hata
Tadayoshi
T
D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007223:Infant; D008297:Male; D012016:Reference Values; D018709:Statistics, Nonparametric