Normal measurements of modified Frank corrected orthogonal electrocardiograms and their importance in an on-line computer-aided electrocardiographic system.
S Talbot, Leonard S. Dreifus, Yoshio Watanabe, R Chiang, K Morris, M. Reich · Heart · 1974
We have used a computer-aided i5-lead hybrid electrocardiographic system to obtain normal measurements throughout life for men and women in different age groups.Amplitude and duration of the P, QRS, and T wave in the modified Frank orthogonal leads were deter- mined.The range of many of these observations was greater than that usually accepted; in particular, the PR interval could be as low as I00 msec and the QRS as long as II5 msec.The QRS and QT intervals were gramme, and therefore present our normal ortho-Received 4 January 1974 gonal limits in relation to age, sex, and heart rate, since these variables have important effects on many measurements.The QT interval is a composite measurement related to both depolarization and repolarization.It is affected by conduction defects (Talbot, I973), and consequently we have introduced a new measurement from the end of the S wave to the end of the T wave, termed the ST interval, which we have found more useful.(This should not be confused with the ST segment, which is measured from the end of the S wave to the beginning of the T wave.)The normal limits according to age, sex, heart rate, and QRS duration are presented.