The spatial frequency distribution of the QRS loop as studied on 154 normal individuals

Abstract

The spatial distribution of the QRS complex of 154 normal individuals was analyzed in this investigation. The three scalar vector components X, Y, and Z were recorded simultaneously at high speed on film, and the Lissajous loops of the three body planes were displayed on the cathode-ray oscilloscope. The spherical coordinates of the instantaneous vectors were determined from the time-based scalar recordings with the aid of a vector coordinating instrument and tabulated functions. The data obtained were plotted into charts, representing the angular distribution as a function of time. The position of the polar vector, representing the spatial orientation of the principal QRS plane, was calculated from plane projection areas. Mean and standard deviation values of the spherical coordinates of the instantaneous as well as the polar vectors were determined for all individuals. The wide range of individual variability observed during the initial and terminal portions of the QRS complex is not fully explained by rotation, anatomic or otherwise. An inherent structural variation was demonstrated by viewing plane deviations and open plane projection vectors as a function of time. Individual scatter is narrow during the time of the peak and for a short interval preceding it. This region of minimal dispersion appears to be of value for comparative studies. There are during this interval well-defined, consistent differences between the male and female groups, as well as between the respective age groups. The group of men between the age of 40 and 50 shows a more marked change than does the corresponding female group. The region defined by the mean and standard deviation values of the spherical coordinates can be plotted as a function of time and serve as a calibration curve against which individual tracings may be tested. More extensive studies and clinical correlation will be necessary before the discriminating power of this method can be fully evaluated.