AI Article Synopsis
- The equivalent current dipole (ECD) model serves as a basic way to represent the heart’s magnetic field, especially during ventricular depolarization, but has limitations that become clear during experiments.
- The study explores deviations from the dipolar pattern by looking at second-order components of current multipole expansion, indicating that these variations can be linked to circular currents in the heart.
- By using analytical expressions and computer modeling, the researchers successfully matched theoretical magnetic field distributions with experimental data, supporting the idea of circular current sources in the heart’s electrical activity.
Article Abstract
The equivalent current dipole (ECD) model is only the first-order approximation in modelling the primary sources of the magnetic field of the heart. From the experimental point of view this fact is particularly evident during the onset of ventricular depolarisation. In this paper we have tried to explain the departures of the experimental maps from the dipolar pattern in terms of the second-order component of the current multipole expansion for the primary source density. The antisymmetric part of this second-order component produces the external magnetic field and is equivalent to a magnetic dipole. To a first approximation it could represent circular currents flowing within the heart. We have derived the analytical expression for the magnetic field normal to the frontal plane produced by an equivalent current dipole and by an equivalent magnetic dipole (EMD) lying in a homogeneous conducting half-space. Using this expression in a least-squares fit computer program we have obtained the appropriate set of ECD and EMD parameters producing the best matching between theoretical and experimental field distributions in normal subjects. The results are in good agreement with the anatomical features of the heart and with the electrophysiology of ventricular activation. With previous theoretical considerations they strongly suggest the presence of divergence-free circular current sources within the heart.
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| http://dx.doi.org/10.1088/0031-9155/32/1/020 | DOI Listing |
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