Magnetic field detection using magnetohydrodynamic effect
First Claim
1. A method comprising:
- identifying a change in a characteristic of an electrogram (EGM) measured by an implantable medical device indicative of the presence of a static magnetic field, wherein the EGM corresponds to cardiac activity of a heart of a patient;
determining a magnitude of the change in the characteristic of the EGM;
detecting the presence of the static magnetic field based at least on the magnitude of the change in the characteristic of the EGM; and
adjusting operation of the implantable medical device in response to detecting the presence of the static magnetic field.
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Accused Products
Abstract
An IMD may transition to an MRI mode automatically in response to detecting one or more conditions indicative of the presence of a strong magnetic field. Large static magnetic fields, such as those produced by an MRI device, may interact with the blood of a patient as it flows through the magnetic field to produce a voltage, a phenomenon referred to as the magnetohydrodynamic (MHD) effect. The voltage produced by the MHD effect is proportional to the strength of the magnetic field. As such, the voltage produced by blood flow in the strong magnetic field of an MRI device may result in a change in a characteristic of an electrogram (EGM). The IMD may detect the change in the characteristic of the EGM caused by the MHD effect and transition to operation in the MRI mode in response to at least the change in the EGM.
15 Citations
19 Claims
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1. A method comprising:
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identifying a change in a characteristic of an electrogram (EGM) measured by an implantable medical device indicative of the presence of a static magnetic field, wherein the EGM corresponds to cardiac activity of a heart of a patient; determining a magnitude of the change in the characteristic of the EGM; detecting the presence of the static magnetic field based at least on the magnitude of the change in the characteristic of the EGM; and adjusting operation of the implantable medical device in response to detecting the presence of the static magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An implantable medical system comprising:
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at least one implantable medical lead that includes at least one electrode; and an implantable medical device connected to the medical lead, the implantable medical device comprising a control module configured to identify a change in a characteristic of an electrogram (EGM) indicative of the presence of a static magnetic field, determine a magnitude of the change in the characteristic of the EGM, detect the presence of the static magnetic field based at least on the magnitude of the change in the characteristic of the EGM, and adjust operation of the implantable medical device in response to detecting the presence of the static magnetic field, wherein the EGM corresponds to cardiac activity of a heart of a patient. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A computer-readable medium comprising instructions that, when executed, cause an implantable medical device to:
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identify a change in a characteristic of an electrogram (EGM) indicative of the presence of a static magnetic field, wherein the EGM corresponds to cardiac activity of a heart of a patient; determine a magnitude of the change in the characteristic of the EGM; detect the presence of the static magnetic field based at least on the magnitude of the change in the characteristic of the EGM; and adjust operation of the implantable medical device in response to detecting the presence of the static magnetic field.
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Specification