Abstract
The essentially 3-dimensional nature of the spatial vectorcardiogram (sVCG) requires that it be studied as a vector sequence in space, and not merely in its projections on the arbitrary frontal, sagittal, and transverse planes. One striking characteristic of the normal QRS sÊ-loop is that it lies approximately in a single "plane of predilection," which does not coincide with any of these 3 arbitrary planes. This paper describes the variations observed in the sVCG, recorded by a cubical lead system, with particular reference to the "QRS plane," in a group of normal subjects and suggests a system for classifying abnormalities of the sVCG, based on the QRS plane.