Age-related criteria for signal-averaged electrocardiographic late potentials in children.

This study examined the age-related criteria of signal-averaged electrocardiographic (SA-ECG) parameters in children. SA-ECGs were obtained in 82 healthy volunteers in six groups depending on age (group 1: 1 day to < 1 month; group 2: 1 month to < 1 year; group 3: 1 to < 6 years; group 4: 6 to < 12 years; group 5: 12 to < 20 years; group 6: 20 to < 40 years). To examine the effect of heart rate on the parameters of SA-ECG, right atrial pacings were performed in 4 children with a ventricular septal defect aged 1-7 years. The root mean square voltage (RMS) was high; and the filtered QRS (f-QRS) duration and the duration of the low amplitude signal (LAS) were low during childhood, especially in infants (group 2), compared with those in adults. Late duration (LD) had no significant difference among age groups. The criteria for ventricular late potential were as follows: RMS < 25 microV, LAS > 35 ms, f-QRS duration > 110 ms, and LD > 35 ms for those age 1 day to < 1 month; RMS < 40 microV, LAS > 30 ms, f-QRS duration > 100 ms, and LD > 35 ms for those age 1 month to < 1 year; RMS < 20 microV, LAS > 40 ms, f-QRS duration > 130 ms, and LD > 35 ms for those age 1 to < 20 years; and RMS < 15 microV, LAS > 45 ms, f-QRS duration > 135 ms, and LD > 35 ms for those age 20 to < 40 years. RMS and LAS correlated with f-QRS duration (r = -0.78 and 0.76, respectively; p < 0.05), suggesting that these parameters are associated with the thickness of the ventricular muscle and the ventricular conduction time. Right atrial pacing had no effect on the measured SA-ECG parameters. The age-related differences in SA-ECG parameters might be due to age-related differences in the thickness of the ventricular muscle and the ventricular conduction time but are not due to differences in the heart rate. The age difference of each parameter on SA-ECG should be considered for ventricular late potentials.