Modified torso vs distal limb electrode placement for performing ECGs in children: A method comparison study

The electrocardiogram (ECG) is routinely performed in children with the limb electrodes positioned on the torso, but few studies have investigated the effects of this modification on the pediatric ECG. Our objective was to assess the agreement between the standard limb lead configuration and a modified torso electrode configuration in normal, healthy children, and to assess the effect of height on that agreement.

185 children aged 5-18 years underwent two consecutive 12‑lead ECGs, one with standard distal limb lead placement and one with the limb leads placed on the torso. Agreement was assessed for 17 ECG parameters (intervals, axes, and amplitudes) using Bland-Altman plots, height-dependent mean error, and false positive rates.

The torso configuration systematically biased the QRS and P wave axes rightwards (towards aVF). Adequate agreement was observed for PR interval and QRS duration, but QTc limits of agreement (±40 ms) were wide. The torso configuration overestimated left-precordial Q, R, and S wave amplitudes and underestimated right-precordial R and S wave amplitudes compared to the distal limb placement. Mean measurement errors increased with the magnitude of the ECG parameter. Mean and variance of measurement errors were more pronounced in shorter children. False positive rates did not differ between the torso and distal limb configurations.

Modified placement of the limb electrodes onto the torso resulted in multiple differences in the pediatric ECG signals. This may lead to misclassification of electrocardiographic abnormalities, particularly in children with measurement values at the upper limits of normal.