Magnetocardiographic localization of accessory pathways using a moving current dipole and a realistically shaped conductor model

Three patients with WPW syndrome were selected for the study. The MCGs were recorded using a second-derivative Superconducting QUantum Interference Device (SQUID) gradiometer in an RF-shielded room. A single moving current dipole model is used in the MCG functional localization process. A realistically-shaped conductor model for the conductivity geometry of the human body torso is applied as a forward model. Realistically-shaped torsos are obtained from MRI by using the boundary element method. Location of the dipole is found by using the MUSIC method. The three-dimensional dipole location was computed every 10 ms from the onset of the QRS wave by the MUSIC method. These 3-D dipole locations were projected onto MRI in order to visualize the propagation of the calculated ventricular source. The results show that MCG is capable of precisely determining the 3-D location of a current source in a noninvasive manner and may be of potential benefits in the treatment of WPW syndrome by catheter ablation.