Magnetic field detection using magnetohydrodynamic effect
First Claim
1. A method comprising:
- detecting presence of a magnetic field based on the output of a magnetic field sensor;
identifying, in response to detecting the presence of the magnetic field, whether a change in a characteristic of an electrogram (EGM) measured by an implantable medical device indicative of the presence of the magnetic field exists;
determining that the detected magnetic field is a static magnet of a magnetic resonance imaging (MRI) device when the existence of the change in the characteristic of the EGM indicative of the presence of the magnetic field is identified;
determining that the detected magnetic field is a handheld magnet when the existence of the change in a characteristic of the EGM indicative of the presence of the magnetic field is not identified; and
adjusting operation of the implantable medical device based on the determination.
1 Assignment
0 Petitions
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.
19 Citations
24 Claims
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1. A method comprising:
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detecting presence of a magnetic field based on the output of a magnetic field sensor; identifying, in response to detecting the presence of the magnetic field, whether a change in a characteristic of an electrogram (EGM) measured by an implantable medical device indicative of the presence of the magnetic field exists; determining that the detected magnetic field is a static magnet of a magnetic resonance imaging (MRI) device when the existence of the change in the characteristic of the EGM indicative of the presence of the magnetic field is identified; determining that the detected magnetic field is a handheld magnet when the existence of the change in a characteristic of the EGM indicative of the presence of the magnetic field is not identified; and adjusting operation of the implantable medical device based on the determination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. 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 magnetic field sensor; and a control module configured to detect presence of a magnetic field based on the output of the magnetic field sensor and, in response to detecting the presence of the magnetic field, monitor an electrogram (EGM) measured by an implantable medical device, identify whether a change in a characteristic of the EGM indicative of the presence of the magnetic field exists, determine that the detected magnetic field is a static magnet of a magnetic resonance imaging (MRI) device when the existence of the change in the characteristic of the EGM indicative of the presence of the magnetic field is identified, determine that the detected magnetic field is a handheld magnet when the existence of the change in a characteristic of the EGM indicative of the presence of the magnetic field is not identified, and adjust operation of the implantable medical device based on the determination. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A computer-readable medium comprising instructions that, when executed, cause an implantable medical device to:
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detect presence of a magnetic field based on the output of a magnetic field sensor; monitor an electrogram (EGM) measured by an implantable medical device in response to detecting the presence of the magnetic field; identify whether a change in a characteristic of the EGM indicative of the presence of the magnetic field exists; and determine that the detected magnetic field is a static magnet of a magnetic resonance imaging (MRI) device when the existence of the change in the characteristic of the EGM indicative of the presence of the magnetic field is identified; determine that the detected magnetic field is a handheld magnet when the existence of the change in a characteristic of the EGM indicative of the presence of the magnetic field is not identified; and adjust operation of the implantable medical device based on the determination.
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24. An implantable medical system comprising:
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at least one implantable medical lead that includes at least two electrodes; and an implantable medical device connected to the medical lead, the implantable medical device comprising; a magnetic field sensor; and a control module configured to detect presence of a magnetic field based on the output of the magnetic field sensor and, in response to detecting the presence of the magnetic field based on the output of the magnetic field sensor, switch from a first sensing vector to a second sensing vector that better senses a change in the characteristic of an electrogram (EGM) indicative of the presence of the magnetic field than the first sensing vector, analyze the EGM sensed using the second sensing vector to determine whether a change in a characteristic of the EGM indicative of the presence of the magnetic field exists, and adjust operation of the implantable medical device based on whether the change in the characteristic of the EGM indicative of the presence of the magnetic field exists.
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Specification