Key result
Current dipoles and tissue anisotropy generate similar cardiac magnetic field magnitudes and falloff rates.
Why the study?
Two different mechanisms from which a magnetic field arises in the heart have not been comparatively modeled to understand their relative contributions.
Both current dipoles with return currents and tissue anisotropy are important mechanisms for generating the heart's magnetic field.
Supports dual-mechanism modeling in magnetocardiography; leaves open relative contributions in vivo.
There are two different mechanisms from which a magnetic field can arise in the heart. The first mechanism has the source of the magnetic field as a current dipole oriented perpendicular to the action potential wave front with the “return” currents flowing in an adjacent volume conductor. The second mechanism is one with no adjacent volume conductor and has a magnetic field that arises due to the anisotropy of the tissue. We see that the two mechanisms produce magnetic fields of similar magnitudes and similar falloff rates as distance from the tissue increases, indicating that both mechanisms are important.
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Murdick et al. (2004) studied Magnetic field of the heart. Current dipole with return currents vs. Tissue anisotropy was evaluated on Magnetic field magnitude and falloff rate. A comparative model demonstrated that both a current dipole with return currents and tissue anisotropy produce magnetic fields of similar magnitudes and falloff rates in the heart.
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