The basic principles of interpretation of the ecg in children are identical to those in adults, but the progressive changes in anatomy and physiology which take place between birth and adolescence result in some features which differ significantly from the normal.
В standard calibration a standard ecg is recorded at 25mmsec and with a frequency cut off of no lower than 150hz in adults, and 250hz in children.
7 normal children under 5 years of age plus a few older children, will show an rsr complex in the right praecordial leads. To be considered normal the width of the qrs should be no more than 10msec longer than normal and the r voltage in v1 should be less than 15mm in infants under 1 year and less than 10mm over 1 year.
The diagnosis of the normal electrocardiogram is made by excluding any recognised abnormality.
В normal ecg values were determined using computer-assisted measurement of the ecgs of 2,141 white children aged 0 to 16 years divided into 12 age groups. These values are plotted on graphs containing the second, fifth, 25th, 50th, 75th, 95th, and 98th percentiles for each age group. This provides a convenient, fast, and practical method for comparing the values found in a given ecg with those.
Note that the heart is beating in a regular sinus rhythm between 60 - 100 beats per minute (specifically 82 bpm). All the important intervals on this recording are within normal ranges.