SWITCH FOR TURNING OFF THERAPY DELIVERY OF AN ACTIVE IMPLANTABLE MEDICAL DEVICE DURING MRI SCANS
First Claim
1. An MRI-compatible electronic medical therapy system, comprising:
- an active medical device (AMD);
a lead wire having a first end extending from the AMD to a distal electrode at a second end thereof for contact with biological cells; and
a normally closed switch incorporated into the lead wire or the electrode so as to be in electrical series with the lead wire, wherein the switch remains closed during normal AMD-related therapy, but temporarily opens in the presence of an induced electromagnetic field so as to create an open circuit between the electrode and the AMD to prevent damage to biological cells in contact with the lead wire or electrode.
1 Assignment
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Accused Products
Abstract
An MRI-compatible electronic medical therapy system is provided for temporarily preventing current flow through an implanted lead wire in the presence of an induced radio frequency, magnetic, or static field. One or more normally closed switches are disposed in series between the AIMD and the one or more distal electrodes. The switch may be incorporated in the AIMD, lead wire, or within or adjacent to the electrode. The switch remains closed during normal AIMD-related therapy, but temporarily opens in the presence of an induced radio frequency, magnetic, or static field so as to prevent current flow through the electrode and lead wire. The switches prevent current from circulating that could be induced by a medical therapeutic diagnostic device, which can cause overheating of lead wires, excessive currents or temperatures and tissue damage.
132 Citations
37 Claims
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1. An MRI-compatible electronic medical therapy system, comprising:
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an active medical device (AMD); a lead wire having a first end extending from the AMD to a distal electrode at a second end thereof for contact with biological cells; and a normally closed switch incorporated into the lead wire or the electrode so as to be in electrical series with the lead wire, wherein the switch remains closed during normal AMD-related therapy, but temporarily opens in the presence of an induced electromagnetic field so as to create an open circuit between the electrode and the AMD to prevent damage to biological cells in contact with the lead wire or electrode. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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5. The system of claim 5, wherein the switching element automatically closes on removal of the induced radio frequency, electrostatic or magnetic field.
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16. A medical device, comprising:
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a medical device for administering therapy or receiving signals including an electronic circuit operably connected to a power source; an electrode electrically connected to the electronic circuit of the medical device and adapted for insertion into or connection to biological tissue; a switch disposed in electrical series with the electrode and the electronic circuit, wherein the switch is normally closed to establish a connection between the electrode and the medical device electronic circuit, but automatically temporarily open to prevent current flow between the electrode and the electronic circuit of the medical device in the presence of an induced radio frequency, static or magnetic field without interrupting the connection between the power source and the electronic circuit of the medical device, and close again to reestablish electrical connection between the electrode and the medical device electronic circuit after removal of the induced radio frequency, static or magnetic field. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method for preventing current generated from diagnostic or therapeutic energy from circulating between an electrode disposed within a human body and a medical device operably connected to the electrode, comprising the steps of:
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providing a medical device having an electronic circuit designed to administer therapy or receive signals via an electrode electrically connected to the medical device; incorporating a switch in series with the electrode and the electronic circuit of the medical device, the switch configured to prevent electric current from flowing between the electrode and the medical device electronic circuit, but not preventing current flow between a power source of the medical device and the electronic circuit; disposing the electrode and the switch into the human body; opening the switch to prevent current to flow between the electrode and the medical device electronic circuit during exposure of the human body to non-medical device related diagnostic or therapeutic electromagnetic energy, in order to prevent undesirable generation of current between the electrode and the medical device electronic circuit by exposure to the diagnostic or therapeutic electromagnetic energy; and closing the switch after exposure of the human body to the diagnostic or therapeutic electromagnetic energy to reestablish electrical connection between the electrode and the medical device electronic circuit. - View Dependent Claims (31, 32, 33, 34)
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35. A method for temporarily preventing current flow through an implanted lead wire in the presence of an induced static, radio frequency or magnetic field, comprising the steps of:
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incorporating a switch in series with the lead wire between proximal and distal ends thereof; electrically connecting the proximal end of the lead wire to an active implantable medical device (AIMD); maintaining the switch in a closed state so as to create a closed circuit between the distal end of the lead wire and the AIMD during normal AIMD-related therapy; automatically opening the switch to create an open circuit in the presence of an induced static, radio frequency or magnetic field; and automatically closing the switch to create a closed circuit on removal of the induced static, radio frequency or magnetic field. - View Dependent Claims (36, 37)
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Specification