Abstract
The highly magnified spatial horizontal and frontal T loops from 50 normal children aged 1 to 13 years were studied.
The following normal values were obtained: (1) Orientation of the maximal T vector: horizontal plane mean, 342 °, SD ± 25.75 °; frontal plane mean, 47 °, SD ± 9.84 °. The maximal T vector always pointed posteriorly from 1 month to 4 years. (2) Angle between maximal QRS and T vectors: horizontal plane mean 45 °, SD ± 10.86 °; frontal plane mean 14 °, SD ± 9.94 °. (3) Rotation of the T loop: horizontal plane: C-CW, 54%; CW, 30 per cent; figure of eight, 16 per cent. Frontal plane: CW, 44 per cent; figure of eight, 40 per cent; C-CW, 16 per cent. (4) Ratio of length-to-width: horizontal plane mean, 7.8; SD ± 7; frontal plane mean, 18; SD ± 9. (5) Magnitude of the maximal T vector: horizontal plane mean, 0.33 mv; SD ± 0.13 mv; frontal plane mean, 0.42 mv; SD ± 0.14 mv.
The significance of the normal T loop was discussed, particularly regarding the importance of recognizing the normal to differentiate abnormal repolarization in infancy and childhood. It is suggested that the population be divided according to age whenever the orientation of the maximal T vector is analyzed.
