Method and apparatus for disconnecting the tip electrode during MRI
First Claim
1. A medical device, comprising:
- a pulse generator;
a lead including an electrode configured to contact body tissue in a body vessel and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths, the first conductive path parallel to the second conductive path;
a first switch electrically coupled in series between the lead conductor and the electrode, the first switch including a non-conductive state, the non-conductive state preventing formation of the first conductive path between the pulse generator and the electrode in the presence of an MRI magnetic field, the first switch including a conductive state in the absence of the magnetic field, the conductive state allowing formation of the conductive path between the pulse generator and the electrode; and
a second switch electrically connected in series between the lead conductor and the electrode, the second switch including a non-conductive state preventing formation of the second conductive path between the pulse generator and the electrode, the second switch including a conductive state allowing formation of the second conductive path between the pulse generator and the electrode when a voltage applied across the second switch exceeds a threshold voltage;
wherein the first switch in the non-conductive state and the second switch in the non-conductive state electrically shields the electrode from at least electromagnetic radiation and induced voltages in the presence of the MRI magnetic field.
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Accused Products
Abstract
A medical device includes a pulse generator, a lead, and an electrode. The lead includes an electrode and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths. The medical device includes first and second switches. The first switch includes a non-conductive state in the presence of a magnetic field, the non-conductive state preventing formation of the first conductive path between the pulse generator and the electrode. The second switch includes a non-conductive state that prevents formation of the second conductive path between the pulse generator and the electrode. The first switch in the non-conductive state and the second switch in the non-conductive state electrically shields the electrode from electromagnetic radiation and induced voltages during a magnetic resonance imaging procedure.
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Citations
24 Claims
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1. A medical device, comprising:
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a pulse generator; a lead including an electrode configured to contact body tissue in a body vessel and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths, the first conductive path parallel to the second conductive path; a first switch electrically coupled in series between the lead conductor and the electrode, the first switch including a non-conductive state, the non-conductive state preventing formation of the first conductive path between the pulse generator and the electrode in the presence of an MRI magnetic field, the first switch including a conductive state in the absence of the magnetic field, the conductive state allowing formation of the conductive path between the pulse generator and the electrode; and a second switch electrically connected in series between the lead conductor and the electrode, the second switch including a non-conductive state preventing formation of the second conductive path between the pulse generator and the electrode, the second switch including a conductive state allowing formation of the second conductive path between the pulse generator and the electrode when a voltage applied across the second switch exceeds a threshold voltage; wherein the first switch in the non-conductive state and the second switch in the non-conductive state electrically shields the electrode from at least electromagnetic radiation and induced voltages in the presence of the MRI magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for delivering therapy, comprising:
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detecting the presence of a magnetic field at a pulse generator, the pulse generator coupled to a lead including an electrode configured to contact tissue in a body vessel and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths, the first conductive path parallel to the second conductive path; switching a first switch electrically coupled in series between the pulse generator and the electrode to a conductive state in the absence of the magnetic field, the conductive state of the first switch allowing formation of the first conductive path between the pulse generator and the electrode; switching the first switch to a non-conductive state in the presence of the magnetic field, the non-conductive state of the first switch preventing formation of the first conductive path between the pulse generator and the electrode; switching a second switch electrically coupled in series between the pulse generator and the electrode to a non-conductive state when a voltage is applied across the second switch that is less than or equal to a threshold voltage, the non-conductive state of the second switch preventing formation of the second conductive path between the pulse generator and the electrode; and switching the second switch to a conductive state upon detection of the voltage applied across the second switch exceeding the threshold voltage, the conductive state of the second switch allowing formation of the conductive path between the pulse generator and the electrode, wherein the first switch in the non-conductive state and the second switch in the non-conductive state electrically shields the electrode from at least electromagnetic radiation and induced voltages in the presence of the MRI magnetic field. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for delivering therapy, comprising:
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operating a pulse generator in a normal mode in the absence of a magnetic field, the pulse generator connected to a lead including an electrode and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths, the electrode configured to contact tissue in a body vessel, the first conductive path parallel to the second conductive path; operating the pulse generator in an MRI mode in the presence of the magnetic field; emitting one or more therapy pulses from the pulse generator at a first voltage level when the pulse generator is operating in the normal mode, the one or more therapy pulses at the first voltage level reaching the electrode via the first conductive path; and emitting one or more therapy pulses from the pulse generator at a second voltage level when the pulse generator is operating in the MRI mode, the second voltage level greater than or equal to the first voltage level plus a threshold voltage, the one or more therapy pulses from the pulse generator at the second voltage level reaching the electrode via the second conductive path. - View Dependent Claims (24)
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Specification