Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Patent
1992-04-09
1994-05-17
Kamm, William E.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
607 38, A61N 136
Patent
active
053124480
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a medical appliance which can be implanted in the body of a living organism, having means for electrically stimulating tissue contractions and a means for detecting stimulated tissue contractions.
2. Description of the Prior Art
A medical appliance in the form of a cardiac pacemaker is disclosed in European Application 0 236 562 having a terminal which carries the stimulation potential and a terminal which carries a reference potential. The means for detecting stimulated tissue contracts has two terminals and forms therefore a signal corresponding to the potential difference between the two terminals. The pacemaker has means for applying the reference potential to the body of the living organism, and a bipolar electrode which has two contact parts which can be brought into contact with the tissue to be stimulated stimulating a tissue contraction the terminal of the means for stimulation which carries the stimulation potential is connected to at least one of the two contact parts of the electrode and the terminal of the means for stimulation which carries the reference potential is connected to the means for applying the reference potential, and following stimulation one of the terminals of the means for detecting stimulated tissue contractions is connected to one of the two contact parts of the electrode.
More specifically, the aforementioned known cardiac pacemaker has means for stimulating the cardiac tissue, connected on the output side via a terminal which carries the stimulation potential to a first contact part at the distal end of the electrode and via a terminal which carries a reference potential to the housing of the cardiac pacemaker. Corresponding means are connected on the input side to the reference potential, to a second, annular contact part of the bipolar electrode, on the other, in order to detect the reaction of the heart to the stimulation (stimulation response). Due to the fact that the first contact part, to which the stimulation potential is applied, and the second contact part, which detects the stimulation response, are preferably arranged at a distance from one other of at least 0.5 cm, there is a reduction in the superimposition of the detected stimulation response by means of the polarization phenomena produced around the first contact part during the preceding stimulation in the tissue region.
SUMMARY OF THE INVENTION
In accordance with the principles of the invention in a medical appliance of the type present therefor; following stimulation the other terminal of the means for detecting stimulated tissue contractions is connected to the other contact part of the electrode. This stimulated tissue contraction is thus detected in a bipolar fashion between the two contact parts of the electrode. Although it is known, inter alia from U.S. Pat. Nos. 4,532,931, 4,726,379 and French Patent No. 2,524,808, to detect tissue contractions in a bipolar fashion, the previously known examples concern the detection only of spontaneous and not of stimulated tissue contractions. Because in the appliance according to the invention the two contact parts are in contact with the tissue region to be stimulated, in the region of the two contact parts the tissue will have approximately the same electrical potential following stimulation due to the polarization associated therewith. Since the means for detecting stimulated tissue contractions forms a signal corresponding to the potential difference between its terminals, and following stimulation these terminals are each connected to one contact part, the polarization of the tissue cannot therefore lead to any appreciable output signal of the means for detecting stimulated tissue contractions, which means that overloading of the means for detecting stimulated tissue contractions is prevented. If a stimulation triggers a tissue contraction, since the change in potential of the tissue associated with the stimulated tissue contraction propagates at a finite speed, the
REFERENCES:
patent: 4532931 (1985-08-01), Mills
patent: 4558702 (1985-12-01), Barreras et al.
patent: 4579119 (1986-04-01), Callaghan
patent: 4726379 (1988-02-01), Altman et al.
patent: 4821724 (1989-04-01), Whigham et al.
patent: 4858610 (1989-08-01), Callaghan et al.
Hognelid Kurt
Holmstrom Nils
Strandberg Hans
Kamm William E.
Schaetzle Kennedy J.
Siemens Aktiengesellschaft
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