QT interval and final portion of T wave: measurements and dispersion in infants born at high altitude

BACKGROUND: This research was conducted to determine whether the depolarization and repolarization cardiac process of children born at high altitude differs from that of children born at lower altitudes. METHODS: We studied three groups of 30 healthy newborns in the Venezuelan Andes. Group 3500 m consisted of infants born at 3500 m above sea level; Group 3000 m of infants born at 3000 m above sea level and Group 1600 m of infants born at 1600 m above sea level. Conventional 12-lead electrocardiograms were recorded in the 90 newborns. Corrected QT interval, duration from the peak to the end of the T wave, dispersion of QT interval and of the final portion of T wave and heart rate were computed in each subject. RESULTS: The findings of the present study show that infants born at high altitude (Groups 3500 and 3000 m) had a significantly longer corrected QT interval and a significantly shorter peak-to-end of T wave interval. Neither the heart rate nor the indexes of dispersion of the depolarization-repolarization process revealed abnormal values or significant differences among the groups. CONCLUSIONS: These results suggest that the depolarization and repolarization cardiac process of infants born at high altitude differs from that of children born at lower altitudes.