A Study of the Vector Magnetocardiographic Waveform

A description of the measurement techniques for obtaining vector magnetocardiograms (MCG) and a discussion of the significance of the MCG is presented. A map of vector MCG is shown in terms of its three components on a plane above the chest for both the magnetic analog of the QRS wave and the T wave. The waveform of the vector MCG is described and contrasted with the electrocardiogram (ECG). Studies of the variation of MCG patterns with age and weight are performed on twelve separate subjects. The data reveal a correlation between the MCG QRS amplitude and weight, and in the younger subjects a large T wave relative to the QRS amplitude. It is concluded that further studies of MCG waveforms are required to establish the nature and extent of the correlation. The amplitude of the MCG is a physically significant quantity, in that it is directly related to the magnitude and configuration of the current system in the heart and its vicinity. A discussion and calculation of a theoretical model to account for the current distribution associated with the MCG is presented.