Spatial Magnitude, Orientation, and Velocity of the Normal and Abnormal QRS Complex

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Abstract
Curves of spatial magnitude, orientation, and velocity of the QRS complex were obtained by digital computation from 252 normal and 328 abnormal orthogonal electrocardiograms (Frank system). An attempt was made to evaluate the diagnostic usefulness of this type of spatial data display. Because of interindividual variability in QRS duration it was not possible to compare accurately individual records with normal standards. Normalization in time was, therefore, necessary by dividing each QRS complex in time in 10 equal parts. Mean curves were computed for the normal control group and eight pathologic entities. Although differences in configuration between the various groups became evident, a large overlap between the various ranges prevented an efficient classification for diagnostic purposes. A point-by-point separation between normal ranges and individual curves showed high recognition rates for abnormalities without specific diagnostic classification. The highest information content appeared to be present in curves of spatial orientation. Since time-normalization and numerical statistical analysis of multiple points are not feasible with presently available analog computers, the question is raised whether digital computation is not more efficient in diagnostic classification of electrocardiograms.