Signal Average ECG in Healthy Children

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Abstract

Background

The signal average electrocardiogram is a useful method to identify children in risk of severe ventricular arrhythmia, either with surgical repaired Fallot tetralogy or another congenital cyanotic heart diseases. Most recently, other indications of this study appeared, such as transplants, Duchenne disease, cytostatic cardiotoxicity, etc.

Method

To establish criteria of normality, 100 healthy children were studied, in groups of 20 with ages between 1-30 days, 31-days-12 months, 1-5 years, 6-10 years and 11-15 years. These groups were compared between them and with 50 healthy volunteers adults. The studies were alone with an ART 1200-EPX equipment, averaging 200 QRS complexes.Using 5 to 250 Hz pass band filters, the duration of the QRS, the length of the signal below 40 mV and the root mean square of the add of the voltages of the last 40 m sec were analyzed in the time domain.In the frequency domain was used the Blackman-Harris window, involving a segment of 120 m sec beginning 20 m sec before the end of the QRS complex, and up to 100 m sec of the ST. The high frequency components were evaluated in two areas ratio: 0-20/20-50 and 10-50/20-50. The leads X, Y, andZ were studied for spectral analysis.

Conclusions

In the time domain it was observed that: 1) QRS complex showed and increment of duration with age, the difference being statistically significant between age groups and in relation to healthy adults (p < 0.001). 2) The length of the signal below 40 mV was significantly lower (p < 0.01) in the newborn, related to the other four groups, which didn't show differences between them. All of them had significantly lower values than healthy adults (p < 0.001). 3) The root mean square values were significantly higher in the newborn compared with children of other groups (p < 0.002). It was also higher in all children groups compared with healthy adults (p < 0.001). In the frequency domain, the values were higher in the groups of newborn children and in the group of 31 day to 12 months, with no statistically significant difference between the different groups. We found a significant difference between all children groups and adults, only when the area ratio used was 0-20/20-50 (p < 0.001). The spectral analysis did not show differences between age groups, but we found differences between the children groups and the adults, only when the area ratio used was0-20/20-50(< 0.001). The spectral analysis did not show differences between the age groups and the adults.