Research and application of multi-chamber heart magnetic field model

Abstract

A multi-chamber heart magnetic field model with two atria and two ventricles, boundaries of which were picked up from a magnetic resonance imaging, was established based on the boundary element method (BEM). Moreover, the model-based 36-channel cardiac magnetic field data and magnetic field maps at a specific time were analyzed. We also studied the heart electrical activity during ST-T segment from patients with complete right bundle branch block (CRBBB) and complete left bundle branch block (CLBBB) by the model, respectively. Results show that the model-based magnetic field map generated by the electrical excitation with a moving single current dipole in single bundle branch is similar to the magnetocardiogram (MCG) of the CRBBB/CLBBB patient acquired using a superconducting quantum interference device (SQUID) in cardiac repolarization. It demonstrates that the multi-chamber heart BEM model can be used to study cardiac magnetic inverse problem of CLBBB/CRBBB patient. In addition, two evaluation criteria are given as follows: the ratio of the maximum on the magnetic field strength measurement plane in the multi-chamber model to that in the single-chamber model; and the ratio of root mean squares of the magnetic field strength at the 36 measurement points of the two models. This result indicates that the magnetic field maps generated by the multi-chamber heart model are close to the measured MCG maps. In this model, the strength and topography of the magnetic field lie in the conductivity parameters of cardiac tissues, the position and the number of the equivalent current dipoles.