A Comparative Analysis of Several Corrected Vectorcardiographic Leads

Abstract

The sensitivity of several corrected vectorcardiographic leads to dipolar, quadripolar, and octapolar components of the equivalent cardiac generator was determined in an electrically homogeneous torso model of the human body. A new experimental method, which insured that the desired parameters were determined for the entire cardiac region, was employed. Three complete vector systems were thus studied: McFee's axial, Frank's, and the SVEC-III. Individual leads also studied included the tetrahedron X (lead I), the tetrahedron Y (lead aV_F), the "symmetrical Y," and two grid types of anteroposterior connections. Except for poor adjustment of scale factors the axial leads were found to be the best corrected of the three complete systems. With relative X, Y, and Z channel sensitivities of 0.92, 1.00, and 0.66, respectively, the axial lead system can be recommended as the best of the three. Of all the connections studied, we found the X lead of the SVEC-III system to be the most inadequately corrected. We failed to confirm that the inclusion of weighted back electrode potentials, as employed in Frank's Y lead, improves the characteristics of the neck to left leg connection as a vertical lead. We find the symmetrical Y lead superior to both lead aV_F and the neck to left leg connection The grid type of anteroposterior connection is superior to the other types of corrected Z leads that we investigated, but could probably be corrected further by improvements in design. The use of corrected leads is to be encouraged as a means of achieving standardization and approximating the biophysical conditions implicit in the basic concept and purpose of vectorcardiography.