Ambulatory monitoring in normal children.

An Ambulatory ECG monitoring (AM) was carried out over a 24 hr. period on 90 healthy children divided into 3 age groups (lst week of life, 1 year of age and 5 years of age). There was a high number (about 50%) of unusable registrations because of detached electrodes, broken leads, and artifacts. The AM on children is characterised by: a) high values of the maximum frequencies (mean maximum absolute frequency 178 at birth, 164 at one year, 154 at 5 years); b) a great difference between the maximums and minimums; c) hourly variations related, above all, to feedings in the new-born babies and of a circadian type in the 5 years old children; d) almost constant marked sinus arrhythmias (80%); extremely rare extrasystolia (7.5 atrial, 2.5 ventricular) and always isolated; e) presence of upward (27%) and downward deflection (10%) of the J point sometimes accompanied by modifications of the T wave (22%).