A theoretic analysis of the effects of dipole eccentricity upon the manifest vectors, the manifest QRS loops and the potential of the central terminal.

Assuming homogeneous conductivity and a limitless medium, a theoretic analysis accomplished by employing a model leads to the conclusion that dipole eccentricity produces a systemnatic error in the magnitude and direction of the instantaneous manifest vectors, the manifest QRS loops and the potential of the central terminal. Exaggeration of the electrical rotation of the heart and other electrocardiographic problems are discussed as possible manifestation of dipole eccentricity. Certain correlations applying to spatial vectorcardiography are made from simultaneous study of the theoretic back potential, the AP lead of the cube, and the potential of the central terminal. IN a previous paper' the author reported the results of a theoretic analysis of the errors incident to the assumption that the cardiac dipole remains at the center of the geometric figures commonly employed as frames of reference in vectorcardiographic technic. This study led to the investigation of the Einthoven triangle from the same standpoint. Accordingly, it was felt that it would be advantageous to be able to measure, simultaneously , the three extremity potentials, the potential of the back electrode of the tetra-hedron, and the potentials at the two electrodes employed in measuring the anterior-posterior projections of the vectors of the cube. At the same time that the construction of the model designed for this purpose was completed, Frank's papers2'3 on the same subject appeared in the literature. Frank's approach to the analysis of errors introduced into the manifest direction and magnitude of the cardiac potentials by eccentricity of the dipole involved restricting the dipole to the frontal plane and to a single location during the inscription of the QRS complex. Frank indicated, however, that he was completely aware that an anterior-posterior component of the dipole axis would increase the error and also that movement of the dipole during the process of accession would modify the error. The approach which the author had projected , employing the above mentioned model, involves moving the dipole in three-dimensional space, and studying the effect on the manifest direction and magnitude of the cardiac vector as plotted on the Einthoven triangle. At the same time the potential of the central terminal is studied for each observation. The effects of eccentricity errors as they would appear in the horizontal components of the loops of the tetrahedron and the cube are also investigated. The employment of a model contributes to greater ease of calculation and to visualization but not …