A method for detecting myocardial abnormality by using a total current-vector calculated from ST-segment deviation of a magnetocardiogram signal

Hosono

Chiba

et al. 2003

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The paper presents an evaluation of the possibility of using fetal magnetocardiogram (FMCG) signals to estimate and classify the accessory pathway in fetal Wolff-Parkinson-White (WPW) syndrome. The FMCG signals of two fetuses with WPW syndrome (type A) were detected using a 64-channel superconducting quantum-interference device system. An average across the cycles of these signals was taken to obtain clear WPW signals. To determine the direction and position of the accessory pathway in a fetal heart accurately, the accessory pathway and activated pathway at the peak of the QRS complex thus obtained were estimated for each fetus, using a single-dipole model. The phase angle (about 90 degrees) between the equivalent current dipoles (ECDs) was the same for both fetuses. This angle suggested that the accessory pathway is in the left side of the heart, i.e. that the pathway exists in the left ventricle, which indicates type A WPW syndrome. Identification of the position of the accessory pathway in a fetus with WPW syndrome from the angle between the ECD of the accessory pathway and the ECD of the peak in the QRS complex was thus demonstrated.

Section: Fmcg Analysismentioning

confidence: 98%

Classifying cases of fetal wolff-parkinson-white syndrome by estimating the accessory pathway from fetal magnetocardiograms

Hosono

Chiba

et al. 2003

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“…To visualise the epileptic discharge current inside the brain two-dimensionally, we produced current-arrow maps by deriving the normal component Bz of the magnetic field (Kandori et al, 2001). Such current maps are useful for reviewing neural networks directly and topographically without dipole estimation, although the head sphere shape affects the current-arrow pattern.…”

Section: Signal Analysismentioning

confidence: 99%

Visualisation method of spatial interictal discharges in temporal epilepsy patients using magneto-encephalogram

Miyashita

et al. 2002

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The aim of the study was to develop a method for investigating how interictal epileptic discharges in temporal epilepsy patients are activated spatially. The activity was measured using magneto-encephalography (MEG). The MEG data were used to produce a current-arrow map that reflected the topographic distribution of the electrical current for each peak epileptic waveform. A large current distribution was obtained that appeared to be contained in the limbic structure, in each temporal lobe. The large current orientation indicated two opposite directions. Furthermore, the decrease in the maximum strength of the current-arrow, depending on the medication (e.g. the decrease from 11 to 6 pT m-1 in the left temporal lobe (contralateral stimuli)), suggested that the discharge distributions could be used to verify the efficacy of medication. Thus the topographical visualisation method could be a new strategy for diagnosis in temporal epilepsy patients.

“…Although a volume conductor and tissue anisotropy have an influence on the cardiac currents, this visualisation technique has provided a high detection rate in the diagnosis of ischaemic and arrhythmic heart diseases in adults (TSUKADA et al, 2000a;YAMADA, et al, 200 1;2002;KANDORI et al, 2001a;2002;SATO et al, 2001;2002;SHIONO et al, 2002;KANZAKI et al, 2003). In particular, spatial current dstributions estimated from MCGs taken from adults with long-QT syndrome (LQTS) have led to a more accurate characterisation of this syndrome and revealed that it actually consists of two sub-types .…”

Section: Introductionmentioning

confidence: 98%

Identifying patterns of spatial current dispersion that characterise and separate the brugada syndrome and complete right-bundle branch block

Shimizu

Yokokawa

et al. 2004

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The aim of the study was to detect patterns of spatial-current distribution in the late QRS and early ST-segments that distinguish Brugada-syndrome cases from complete right-bundle branch block (CRBBB). Magnetocardiograms (MCGs) were recorded from Brugada-syndrome patients (n = 6), CRBBB patients (n = 4) and the members of a control group (n = 33). The current distributions at six time points from Q-onset were estimated by producing current-arrow maps (CAMs). The angle of the current arrow of maximum amplitude at each time point was calculated. In the Brugada cases, the characteristic ST elevation was seen above the upper right chest, and abnormal currents appeared to be present in the right-ventricular outflow tract (RVOT). The angles of the abnormal arrows were -78 degrees +/- 51 degrees at 100 ms and -50 degrees +/- 61 degrees at 110 ms. In the cases of CRBBB, wide S- and R-waves were recorded above the upper right and lower right chest, respectively. The angles of the abnormal arrows for CRBBB were 152 degrees +/- 19 degrees at 100 ms, 159 degrees +/- 20 degrees at 110 ms, and 157 degrees +/- 19 degrees at 120 ms. The findings suggest that an abnormal current from the RVOT to the upper left chest may be a feature of the Brugada syndrome, and that the direction of this current is completely different from that seen in CRBBB.