Age-Related Criteria for Signal-Averaged Electrocardiographic Late Potentials in Children

Han, Heon Seok; Cha, Ki Moon

Abstract

PURPOSE: Ventricular late potentials have been shown to predict malignant ventricular arrhythmia and sudden cardiac death in patients with myocardial infarction and cardiomyopathy. Low amplitude and high frequency potentials at the end of the QRS complex can be detected on the body surface using signal-averaged electrocardiogram(SAECG). This study determines the age-related criteria of SAECG parameters and age-related differences.
METHODS
SAECGs were obtained in 58 healthy children in five age groups(<1mo, 1-11mo, 1-5yr, 6-11yr, and 12-15yr). Three orthogonal leads(X, Y, Z) triggered with R-waves were amplified. In all recordings, a minimum of 250 beats were averaged after filtering with a 40Hz high- pass filter and 250Hz low-pass filter with noise level less than 0.7microvolt.
RESULTS
The filtered QRS(f-QRS) duration was low, and the root mean square amplitude of terminal 40ms of f-QRS(RMS40) was high before 6years of age. The duration of low amplitude signal under 40microvolt(LAS) and late duration(LD) changed little during childhood. The criteria for significant ventricular late potential were as follows : f-QRS>98ms, RMS40<105microvolt, LAS>27ms, and LD>40ms for <1mo; f-QRS>109ms, RMS40<98microvolt, LAS>20ms, and LD>49ms for 1-11mo; f-QRS>114ms, RMS40<33microvolt, LAS>33ms, and LD>39ms for 1-5yr; f-QRS>112ms, RMS40<39 microvolt, LAS>30ms, and LD>45ms for 6-11yr; f-QRS>117ms, RMS40<18microvolt, LAS>37ms, and LD>30ms for 12-15yr. RMS40 and LAS correlated with f-QRS duration(r=-0.75, and 0.45 respectively, P<0.05), suggesting that these parameters are associated with ventricular muscle thickness and ventricular conduction time.
CONCLUSION
Age-related differences in SAECG parameters may be due to ventricular muscle thickness and ventricular conduction time. This should be considered for the evaluation of ventricular late potential.