Spatial analysis of the three dimensional components of a magnetocardiogram

Abstract

In this study, the spatial distribution of a cardiomagnetic vector field featuring multiple measurement planes obtained by separated distance was analyzed. Each of the vector components comprising a magnetocardiogram (MCG) and normal and tangential components are measured using an individual MCG measuring system respectively. Results on the overlapping time-wave forms of vector MCG in the case of a normal adult subject (40 years old) was presented. Where a localized single current source exists, each time-wave form must theoretically have a similar figure. However, the peak height ratios (Q, R, S, T) are different for each time-wave forms. On the other hand, the vector MCG time-wave forms of a 5 year old child showed a shape almost similar to that of adults, thought to be due to the relatively small size of the infant heart. However, it was observed that the vector fetal MCG was hardly influenced by a change by the fetal physique. For the next analysis of the vector MCG, changes in the magnetic field strength in distance z from the chest wall were measured. The magnetic field strength decreases according to the distance from the subject, although attenuation curves are different on each occasion This characteristic is the reflected difference in the current source depth in the heart. Here, another method was developed for current estimation using the attenuation factor of distance, which was obtained by calculating the change in the magnetic field strength against the distance r with 1/r/sup /spl alpha//. Current sources were estimated using the attenuation factor. This study showed that vector MCG measurement is helpful in the analysis of the current distribution.