Objective: This study aimed to evaluate the normal ranges of ventricular early repolarization intervals in healthy children according to age and sex.

Material and Method: Patients were divided into seven groups: 0-3 months, 3 months to 1 year, 1-3 years, 3-5 years, 5-9 years, 9-13 years, and 13-18 years. All patients underwent transthoracic echocardiography and 12-lead electrocardiography (ECG). The following parameters were evaluated: left ventricular mass (LV mass), ejection fraction (EF), mitral E and A velocities, E velocity deceleration time (DT), E/A ratio, mean heart rate (HR), repolarization intervals (QT, QTc, JT, JTc, JTp, JTpc), and repolarization dispersion intervals and rates (Tpe, Tpe/QT, Tp/QTc, Tpe/JT, Tpe/JTc).

Results: The median patient age value was 8.75 years (0.96 months-19.71 years). Heart rate (HR), JTp, JTpc, JT, JTc, QT, QTc, Tpe, Tpe/QT, Tpe/QTc, Tpe/JT, Tpe/JTc values are respectively 92 min-1 (54.60-141), 184 ms ( 98.33-249), 225.60 ms (162.04-279.90), 240 ms (141.67-316), 295.63 ms (240.25-336.76), 322 ms (216.67+398), 398.36 ms (350.69-454.93), 57 ms (27.50- 92), 0.18 (± 0.02), 0.14 (± 0.02), 0.24 (± 0.03), 0.19 (± 0.03).

Conclusion: Intervals such as repolarization times and repolarization dispersion are used to predict arrhythmias. We believe that in cases where it is difficult to determine the endpoint of the T wave, the evaluation of JTp and JTpc can provide useful information, and knowing the normal ranges of JTp and JTpc according to age and sex can provide useful information.