Electrocardiographic cancellation: Some observations concerning the "nondipolar" fraction of precordial electrocardiograms

Document Type

Article

Publication Date

1-1-1958

Publication Title

American Heart Journal

Volume

56

Issue

3

Abstract

Nondipolar (local influence) components of the electrocardiographic generator were investigated by comparing leads derived from the apical portion of the precordium with Lead aVR. An advanced type of four-electrode cancellation technique was employed for this purpose. The data were interpreted on the basis of an ancillary study of cancellation in electrocardiographic models, in which deviations from simple dipolar behavior were represented as translocation of the equivalent cardiac dipole during depolarization. Both studies appeared to confirm predictions based on the null-lead theory of cancellation that (1) the inherent properties of cancellation networks render them relatively insensitive to the electromotive forces of the heart, and (2) there is prior assurance of complete cancellation at numerous pairs of instants during depolarization. The location of the equivalent cardiac dipole is not necessarily identical at each instant of complete cancellation. On the contrary, progressive translocation of the dipole is likely to have occurred between two such instants. The 2-channel registration technique employed in this study revealed definite electrocardiographic nondipolarities over the apical precordium, the clinical significance of which requires further clarification. Unfortunately, it appears that the cancellation technique, at least in its present form, will provide relatively little detailed information about deviation of cardiac behavior from the simple fixed-location dipolar schema. © 1958.

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