Behavior of the electrocardiographic T peak to end interval in childhood

Abstract

Background: The T-wave peak to T-wave end (TpTe) interval reflects spatial and transmural dispersion in repolarization and serves as an arrhythmogenic index. Normal TpTe interval data in children are lacking. We evaluated the effects of age, gender, heart rate, leads (II and V(5)) on TpTe and T-wave voltage.

Methods: Four hundred healthy children (age 4 days to 16.7 years) were enrolled. From a resting 12-lead digital ECG, TpTe, RR, QT, JT intervals, and T amplitude were measured (leads II and V(5)). Bazett and Fridericia formulas were applied to TpTe for heart rate correction and TpTe/QT and TpTe/JT were calculated. Descriptive and analytical statistics were applied, significance level set at P < or = 0.05.

Results: TpTe in leads II and V(5) correlate well. Contrary to adults, no gender differences in TpTe were observed in childhood. TpTe lengthens with increasing age, and is inversely related to heart rate. TpTe 98th percentile is 85 msec in first 5 years, increasing to 92 msec in adolescence. TpTe Fridericia is a good correction formula in childhood; TpTe Bazett overcorrects in the younger age. TpTe/QT and TpTe/JT are longer in younger subjects due to greater QT shortening than the TpTe interval at higher heart rates.

Conclusions: In children, TpTe in lead II and V(5) correlate well. The TpTe interval lengthens with advancing age as heart rate diminishes. TpTe Fridericia is a good correction formula in children. Younger subjects have higher TpTe/QT and TpTe/JT indices compared to older children. T-wave voltage increases with age, tallest in the 5-10-year-age group particularly in V(5).

Figure 1

TpTe II mean (circle), and calculated 95% confidence intervals (horizontal bars represent the limits) for the three heart rate groups; <100 beats/min, 100 to 149 and 150 and above. TpTe in milliseconds, bpm = beats per minute.

Figure 2

TpTe Fridericia lead V₅ mean (circle), and calculated 95% confidence intervals (horizontal bars represent the limits) for the four age groups; 0–1, 1–5, 5–10, >10 years.

Figure 3

TpTe/QT (lead V₅) mean (circle), and calculated 95% confidence intervals (horizontal bars represent the limits) for the four age groups; 0–1, 1–5, 5–10, >10 years.