Analysis and estimation of excitation conduction with Wolff-Parkinson-White syndrome patients based on a 3-D magnetocardiogram

The purpose of this paper is to evaluate the accessory pathway of the Kent bundle in the Wolff-Parkinson-White (WPW) syndrome. We measured three-dimensional (3-D) vector measurements of magnetocardiograms (MCGs) for normal subjects and patients with the WPW syndrome, using 3-D second-order gradiometers connected to 39 dc SQUIDs, which can simultaneously detect magnetic field components perpendicular to the chest wall (Bz) and tangential to the chest wall (Bx, By), respectively. Source location for the accessory pathway was estimated by 3-D magnetic field components using the equivalent current dipole method. The magnetic field map of the delta wave obtained from Bz was not helpful in estimating the location and the number of sources, owing to the lack of a dipole pattern. On the other hand, by referring the magnetic field maps of the delta wave obtained from Bx and By, the multiple sources (two sources) overlapping in time were clearly estimated. We demonstrated that 3-D MCG measurements are effective for analyzing multiple sources overlapping in time.