Frequency analysis of premature ventricular contraction using 3-D MCG measurements

The authors carried out three-dimensional (3-D) vector measurements of the magnetocardiogram (MCG) on a subject with premature ventricular contraction (PVC) and ten normal subjects using a 39-channel SQUID system. This SQUID magnetometer can detect magnetic field components perpendicular to the chest wall (Bz) and tangential to the chest wall (Bx,By) simultaneously. The authors used principal component analysis in order to compare the normal sinus rhythm of the PVC patient with the sinus rhythm of ten normal subjects. The results showed that the frequencies in the MCG waveforms of the PVC subject were dominated by lower frequencies (less than 10 Hz) than in normal MCGs, and the frequency distribution of Bx was different from those characteristic of Bz and By