Document Detail

Two-dimensional mapping of impedance magnetocardiograms.
MedLine Citation:
PMID:  12083307     Owner:  NLM     Status:  MEDLINE    
A new method for measuring two-dimensional (2-D) impedance magnetocardiograms (I-MCGs) and magnetocardiograms (MCGs) above the heart simultaneously, has been developed. The I-MCG's and MCG's signals are recorded by using a superconducting interference device (SQUID) system. To measure the I-MCG and MCG signals, four first-order gradiometers with an 18-mm diameter and a 50-mm baseline were used. The SQUIDs are driven by a flux-locked-loop circuit with a frequency range higher than that of an ac-current (40 kHz) with constant amplitude passed through a subject. The output of the circuit is filtered through two circuits: one for measuring the I-MCG signals and one for measuring the MCG signals. The I-MCG signals are obtained by demodulating the magnetic field, which is detected by the gradiometers, at the frequency of the ac current. As a result, the I-MCG signal reflects the change in spatial distribution of conductivity caused by the movement of the heart muscle and blood volume. A contour map of the 2-D I-MCG signals showed the largest signals occur above the right ventricle and right atrium. In a corresponding current-arrow map, it was found that the large current arrows occurred above the right side of the right ventricle. Furthermore, it was found that the systole and diastole timings obtained from the first-derivative I-MCG signal and the phonocardiogram were different. These results show that primitive 2-D I-MCG signal can provide much physiological information on the circulatory movement of the heart.
Akihiko Kandori; Tsuyoshi Miyashita; Daisuke Suzuki; Koichi Yokosawa; Keiji Tsukada
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  IEEE transactions on bio-medical engineering     Volume:  49     ISSN:  0018-9294     ISO Abbreviation:  IEEE Trans Biomed Eng     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-06-26     Completed Date:  2002-08-02     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0012737     Medline TA:  IEEE Trans Biomed Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  721-8     Citation Subset:  IM    
Central Research Laboratory, Hitachi, Ltd., Kokubunji, Tokyo, Japan.
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MeSH Terms
Body Surface Potential Mapping / methods*
Cardiac Output / physiology
Cardiography, Impedance / instrumentation*,  methods*,  statistics & numerical data
Image Processing, Computer-Assisted / instrumentation,  methods
Magnetic Resonance Imaging
Magnetics / diagnostic use*,  instrumentation*
Models, Cardiovascular*
Sensitivity and Specificity
Reg. No./Substance:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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