Separation of normal and abnormal vectorcardiograms. Use of spatial orientation of initial, central and terminal segmental planes of the QRS loop

By combination of manual measurements of selected instantaneous vectors from orthogonal X, Y, Z leads (SVEC III) and the use of a small digital computer (PDP-5), vectorcardiograms from 14 normals and 74 cardiac patients were analyzed, with special attention to the planarity, tortuosity or “twist” of the QRS and TsÊ loops and loop segments.Quantitative analyses were made of (a) mean planarity of the QRS and T planes, (b) the spatial angles between the initial and the main and terminal QRS planes, taken two at a time, (c) the pre-maximal, maximal and post-maximal planes, taken two at a time, (d) the segmental (or instantaneous) polar vectors, and (e) the spatial orientation of the plane containing the maximal QRS and T vectors and the plane including the QRS and T polar vectors.In this admittedly small sample, these parameters differentiated the normal from the various pathologic conditions and various conditions one from the other quite satisfactorily, and in many respects were superior to differentiation by-qualitative loop inspection and quantitative instantaneous vectors.