SIGNAL-AVERAGED ELECTROCARDIOGRAPHY IN HEALTHY-CHILDREN - RELATIONSHIP WITH AGE, SEX, AND ANTHROPOMETRY

Signal-averaged electrocardiograms (SAECGs) have been found to be infl uenced by sex and anthropometry in adults. The purpose of this study w as to evaluate this relationship in children. Total filtered QRS durat ion (TQRS), duration of high-frequency, low-amplitude signals in the t erminal portion of the QRS complex that were less than 40 mu V (HFLA) root-mean-square voltage in the last 40 ms of the filtered QRS (RMS40) were determined by high-resolution electrocardiographic (ECG) recordi ng (MAC 15 ECG System, Marquette Electronics, Milwaukee, WI). These pa rameters were correlated with age, sex, body weight, height, relative weight, body mass index, and body surface area. As HFLA and RMS40 were not normally distributed, they were logarithmically transformed for r egression analysis. The best subset multiple regression procedure was used to evaluate the variables that would optimally influence SAECG me asurements and to obtain regression equations for the prediction of ea ch SAECG parameter. Although univariate analysis shows thar almost all the body characteristics and age are significantly correlated with SA ECGs, multiple regression analysis reveals that TQRS is significantiy influenced by height (P < .0001), relative weight (P = .012), and body mass index (P = .041); HFLA is influenced by weight (P = .001), heigh t (P = .004), and body mass index (P = .001); and RMS40 is influenced by height (P < .0001) and relative weight (P = .001). Sex is noted to significantly influence both TQRS and RMS40 (P < .0001, P = .002, resp ectively), while HFLA is found to be significantly related to age (P = .001). In summary, SAECGs in Chinese children;are shown to be influen ced by height, weight, and relative weight or body mass index, but not body surface area, while age and sex also significantly contribute to the variation of some SAECG parameters.