A comparison of isopotential surface maps in children with normal and abnormal hearts shows that, in certain conditions, the QRS configuration of the anterior precordial leads may be similar while the isopotential surface maps show marked variations. This difference can be explained when one knows the position of the lead and the total body surface potential changes during QRS. Body surface maps allow one to gain an idea of the location and type of information on the body surface (eg, the presence of multiple maxima and minima give important clues as to the presence of single or multiple intracardiac excitation waves). Quantitative analysis of QRS maps from 45 children show that considerably more information is available by increasing the number of leads to 24, a number not much above that used in current electrocardiography; on the other hand, the data suggest that an increase to above 25 leads will yield primarily redundant information.
Spach MS, Barr RC. The Use of Isopotential Surface Maps in Understanding Clinical ECGs. Am J Dis Child. 1972;124(3):359-363. doi:10.1001/archpedi.1972.02110150057010