A detailed linear, circular and spherical quantitation of the Frank and McFee-Parungao orthogonal electrocardiograms of 166 adolescents is presented.There are significant differences between pubescent males and females: (1) QRS and T magnitudes in the male are greater than in the female.(2) The difference in magnitudes is greater at age 11-15 than at age 16-19, presumably because females reach puberty earlier. (3) The differences in magnitudes are on the X and Z axes but not the Y axis. (4) Males achieve their maximal posterior QRS orientation sooner than females and are more superior as it occurs. (5) The female's T vector is less anterior than the male's. (6) The angular deviation of T from QRS is less in females than males for the horizontal and sagittal planes.There are significant differences between the two lead systems: (1) The McFee-Parungao's voltages are greater than those of the Frank system. (2) On the X axis, the Frank leftward vector is 62% of the McFee, but the terminal rightward vector is 85% of the McFee. (3) On the Y axis, the Frank inferior vector is 76% of the McFee, but initial superior is 90% and the terminal superior 62% of the McFee. (4) On the X axis, 25% is terminally to the right in the Frank, but only 15% in the McFee. (5) The Frank system is oriented slightly more posterior than the MeFee, though the T vectors are not oriented differently.There is no evidence that the spatial QRS and T orientations are related to each other.Additional Indexing Words: Vectorcardiogram T HERE HAVE been numerous studies of normal populations of adults'-7 and chil-dren81-7 using orthogonal dipolar and nonorthogonal vectorcardiographic lead systems, but there has been none for the adolescent. The only quantitative analysis for the normal adolescent either utilized standard electrocardiography'8 or included only a small population as part of a larger group.'7 Most of the quantitations at all ages have been limited and few have used appropriate statistics for circular or spherical data. It has been suggested that the McFee-Parungao system is more orthogonal than Frank's'9 and that it is less distorted in children.20 21Nonetheless, there has been very little data in children with that system.15' 17 From theWe have recently published a very detailed quantitation of both the Frank22 and McFee-Parungao23 orthogonal electrocardiographic systems from age two to nineteen years.'7 Since there were only 105 children included and since there is such great variation with aging, the major importance is that the publication provides a model for complete linear, circular and spherical quantitation and statistical analysis of electrocardiographic data. The present publication is an analysis of 166 adolescents between the ages of 11 and 19 years. It includes 57 subjects from the previous report. Material and MethodsThe 166 normal adolescents were all children of University faculty or University Hospitals personnel, or students in the Cleveland School System. There were an approximately equal number of black and white. All w...

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