The Orthogonal Vectorcardiogram in 100 Normal Children (Frank System)

Abstract

Data recorded by the Frank corrected network in 100 normal children aged 7 months to 16 years have been given on the direction and magnitude of successive instantaneous spatial QRS vectors as projected on the horizontal, sagittal, and frontal planes. Gaussian distribution with remarkably similar, and consistent, ranges was observed for nearly all parameters. Exceptions were the 0.04-second vector and maximum QRS vector. Reasons for this discrepancy have been discussed. Surprisingly good agreement, with comparable ranges, was found with series published on young adults studied by the Frank and SVEC- III methods. This indicates little change in the spatial loop with advancing age, except for a more rapid leftward and posterior progression of successive spatial vectors due to the shorter QRS duration in the younger age groups. Comparison with a smaller group of children of similar age in which the cube system of electrode placement was used showed marked variation of initial and terminal forces in the latter system. Furthermore, when compared to the Frank data, discrepancies in direction of mean vectors existed for each parameter studied. Data have been presented to support the thesis that variable representation of electromotive forces along the antero-posterior or z axis, is responsible for the inconstant performance of the cube system. This lack of performance was not present in the Frank system. It is felt that, with a few specific exceptions, the Frank system will give specific, statistically significant measurements of instantaneous vectors, and it is suggested that it be used in vectorcardio-graphic studies of hemodynamic disorders of the pediatric age group.