Magnetic measurements of cardiac mechanical activity

Roman Maniewski, Toivo Katila, Torsti Poutanen, Pentti Siltanen, Timo Varpula, John Wikswo

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)


The origin of the magnetic susceptibility signal caused by mechanical activity of the heart is studied. Magnetic signals were measured with a second order SQUID (superconductor quantum interface device) gradiometer by applying a homogeneous external magnetic field with magnitude up to 260 A/m. Three experimental methods were used to separate the different components in the magnetic susceptibility signal. First, the thorax of the subject was surrounded by water solution of MnCl2 with various magnetic susceptibilities, then a plastic bag containing a similar solution was placed on the chest of the subject, and finally the chest wall of the subject was immobilized during the measurements by using a special vacuum casting. The results suggest that usually about 65-80% of the signal measured near the heart originates directly from cardiac volume changes.
This cardiac plethysmogram can be separated easily by immobilizing the subject's chest or by surrounding the chest with the liquid, whose magnetic susceptibility is about -5*10-6.
Original languageEnglish
Pages (from-to)662-670
JournalIEEE Transactions on Biomedical Engineering
Issue number9
Publication statusPublished - 1988
MoE publication typeA1 Journal article-refereed


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