Surgery – Truss – Pad
Patent
1995-10-23
1998-07-21
Kamm, William E.
Surgery
Truss
Pad
128908, A61B 50428
Patent
active
057822417
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the field of receiving and measuring biological signals and the surveillance of patients, particularly patients undergoing nuclear magnetic resonance (NMR) examination for example in a magnetic resonance imager (MRI), and has for its object a detector device for electrocardiograms.
BACKGROUND OF THE INVENTION
At present, electrocardiogram signals from patients subjected to an NMR examination are received by means of electrodes with metallic conductors and transmitted to a visualization and/or surveillance apparatus disposed in the shielded enclosure or outside, by means of electric cables of great length, as the case may be shielded and twisted together.
However, these electrical cables, forming antennas, disturb the electromagnetic environment of the NMR apparatus and render false the measurements and, in the case of an imager, the virtual reconstructions (images) obtained by this latter.
Conversely, the field gradients, the radiofrequency fields and the phenomena connected to switching between emitting and receiving coils in the course of an experiment of the NMR type greatly disturb the transmission of the low power signals received at the heart and may, by generation of important false images, render these latter totally unusable, even though the patient is disposed within the interior of the principal magnet of the NMR apparatus.
Moreover, possible movements of the patient (particularly breathing) give rise to movements of said electrical transmission cables in the existing field, from which automatically results an induction of voltages generating false images.
Moreover, the troublesome phenomena described are greatly amplified when the transmission cables have one or several loops.
Thus, the energy stored by the cable or cables, subjected to high intensity electromagnetic fields, at said loops or cable, can be fairly great so as to provoke substantial heating of said cable, which can give rise to burns on the patient's skin on which a portion of the cables rest, particularly when passing through an emission antenna.
Moreover, the placement of the electrodes on the patient in the region of the heart requires, for correct emplacement, the intervention of a specialist, each of said electrodes having to be precisely positioned individually.
It has been proposed, in an attempt to overcome certain of these drawbacks, to use algorithms for correcting the false images generated by the gradients and the radiofrequency fields.
However, these algorithms are not adapted to other than a predetermined type of NMR apparatus, with a given configuration of windings and frequently with a particular NMR sequence, which results in a great loss of flexibility during their application.
Moreover, they do not permit solving the problems of burns, nor the problems of induction of voltage because of the movements of the cables or again the problems of positioning the electrodes.
SUMMARY OF THE INVENTION
The present invention has particularly for its object to relieve all of the recited drawbacks, by simple means, not burdensome and of general application, no matter what the type of apparatus used.
To this end, it has for its object a detector device for electrocardiograms, adapted to be used in a charged and sensitive electromagnetic environment, particularly adjacent or within an NMR apparatus, and more particularly on a patient within the tunnel of the magnet of an NMI, characterized in that it is principally constituted, on the one hand, by at least two non-metallic electrodes, adapted to be applied to the skin of a patient, on the other hand, by a module for filtering and amplifying and electro-optically converting electrical signals from the heart, received by means of said receiving electrodes, disposed in a shielded casing forming a Faraday cage and connected by optical means to a visualization and/or control apparatus and, finally, by a support body of an amagnetic material, bearing the electrodes and the shielded casing containing the module.
BRIE
REFERENCES:
patent: 3757778 (1973-09-01), Graham
patent: 3910257 (1975-10-01), Fletcher et al.
patent: 4041954 (1977-08-01), Ohara
patent: 4181134 (1980-01-01), Mason et al.
patent: 4245649 (1981-01-01), Schmidt-Andersen
patent: 4375219 (1983-03-01), Schmid
patent: 4858617 (1989-08-01), Sanders
patent: 5217010 (1993-06-01), Tsitlik et al.
Boesch Chris
Felblinger Jacques
Kraemer Michel
Muller Gerard
"O.D.A.M." Office de Distribution d'Appareils Medicaux (SA)
Kamm William E.
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