Simplification of the SVEC-III lead system

Abstract An effort was made to develop a simplification of the SVEC-III lead system which would preserve most of its accuracy and immunity to exact electrode-positioning requirements while reducing the number of electrodes in the awkward back positions. A rectangular grid of 30 uniformly spaced back-electrode positions, including the four original SVEC-III Z-lead positions, was tested position by position in comparison with the standard SVEC-III Z lead in ten healthy men and ten patients with different types of cardiac pathology. Potential differences between the single exploring Z electrode and the standard, combined, weighted Z lead were recorded and statistically evaluated as absolute differences, relative differences in respect to peak-to-peak amplitude, and root mean squares. The smallest errors occurred near the center of the rectangle, in an oblique line from upper left to lower right, without appreciable differences between the normal subjects and the patients. The typical error for good electrode positions was in the range of 6 to 15 per cent, which is not negligible, but, as shown in illustrations, would not affect the clinical interpretation appreciably. It is concluded that the simplified SVEC-III system is workable for clinical routine interpretation, probably better than some other corrected lead systems, but not quite as accurate as the original SVEC-III system.