Method and apparatus for detecting static magnetic fields
First Claim
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1. An apparatus for detecting static magnetic fields impinging upon an implantable medical device (IMD), comprising:
- a sensor adapted to provide at least one signal proportional to at least one vector component of a magnetic field;
a circuit adapted to receive the signal and perform a predetermined action when a predetermined quantity exceeds a predetermined threshold value, wherein the at least one signal comprises a first, a second, and a third signal approximately proportional to a first, a second, and a third vector component of the magnetic field, wherein the second and the third components of the magnetic field are approximately orthogonal to the first component of the magnetic field and to each other, and wherein the circuit comprises a first detection circuit and a second detection circuit coupled to an interface and wherein said circuit operatively couples to control circuitry of an IMD.
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Abstract
The present invention provides a method and apparatus for detecting magnetic fields in implantable medical devices. The apparatus includes a sensor adapted to provide at least one signal proportional to at least one vector component of a magnetic field. The apparatus further includes a circuit adapted to receive the signal and perform a predetermined action when a predetermined quantity exceeds a predetermined threshold value.
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Citations
30 Claims
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1. An apparatus for detecting static magnetic fields impinging upon an implantable medical device (IMD), comprising:
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a sensor adapted to provide at least one signal proportional to at least one vector component of a magnetic field;
a circuit adapted to receive the signal and perform a predetermined action when a predetermined quantity exceeds a predetermined threshold value, wherein the at least one signal comprises a first, a second, and a third signal approximately proportional to a first, a second, and a third vector component of the magnetic field, wherein the second and the third components of the magnetic field are approximately orthogonal to the first component of the magnetic field and to each other, and wherein the circuit comprises a first detection circuit and a second detection circuit coupled to an interface and wherein said circuit operatively couples to control circuitry of an IMD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for detecting static magnetic fields impinging upon an implantable medical device (IMD), comprising:
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a first detection circuit adapted to receive a first portion of a signal provided by a sensor positioned in an implantable medical device, wherein the sensor is adapted to sense the presence of a magnetic resonance imaging device;
a second detection circuit adapted to receive at least a second portion of the signal; and
an interface adapted to receive a first notification from the first detection circuit when a first selected quantity derived from the first portion exceeds a first selected value and a second notification from the second detection circuit when a second selected quantity derived from the second portion substantially exceeds a second selected value, and wherein the interface is adapted notify a processor unit operatively coupled within the interior portion of a hermetically-sealed IMD when the second selected quantity substantially exceeds the second selected value, wherein the interface as adapted to provide power to the second detection circuit following the first notification from the first detection circuit that the first selected quantity substantially exceeds the first selected value. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method of detecting static magnetic fields impinging upon an implantable medical device (IMD), comprising:
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sensing a magnetic field impinging upon an IMD system using a sensor;
comparing the magnitude of the magnetic field to a predetermined threshold magnitude;
notifying the IMD system when the magnitude of the magnetic field substantially exceeds the predetermined threshold magnitude, wherein sensing the magnetic field comprises forming three signals proportional to a first, a second, and a third vector components of the magnetic field, wherein the second and the third components of the magnetic field are approximately orthogonal to the first component of the magnetic field and to each other, wherein comparing the magnitude of the magnetic field comprises combining the three signals using a circuit to form a quantity approximately proportional to the magnitude of the magnetic field, wherein comparing further comprises determining if the quantity substantially exceeds a value that would be created in the circuit by a magnetic field with a magnitude approximately equal to the predetermined threshold magnitude, and wherein comparing comprises determining if the quantity substantially exceeds the value that would be created in the circuit by a magnetic field of approximately 1700 gauss. - View Dependent Claims (23, 24, 25)
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26. A method of detecting static magnetic fields impinging upon an implantable medical device (IMD), comprising:
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sensing a first, a second, and a third signal proportional to a first, a second, and a third component of a magnetic field near an IMD using a three-axis sensor, the second and the third components of the magnetic field being approximately orthogonal to the first component of the magnetic field and to each other;
deriving a first quantity from the first signal;
comparing the first quantity to a first selected value using a first detection circuit;
comparing a second quantity derived from the first, the second, and the third signal to a second selected value using a second detection circuit, the second detection circuit being enabled following notification that the first quantity substantially exceeds the first selected value; and
notifying a processing unit in the IMD when the second quantity substantially exceeds the second selected value. - View Dependent Claims (27, 28, 29, 30)
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Specification