Measurements and a simplified interpretation of magnetocardiograms from humans.

To understand and assess the magnetocardiograph, the magnetic field produced by electrical heart activity was mapped around the torsos of one abnormal and six normal heart subjects, at different times during QRS. The measurements are here presented in the form of instantaneous distributions of vector segments 6 cm from the skin, anteriorly. An electrical model is presented which explains the first-order features of these distributions. This model is a simple, rotating bipole heart source of changing strength which produces the same ion currents as measured with surface electrocardiograms and vectorcardiograms; these currents produce a time-changing magnetic field extending outside the torso. Further analysis of second-order details of the distributions