Systems and methods for providing arrhythmia therapy in MRI environments
First Claim
1. A method for operating an implantable medical device (IMD) implanted within a patient in the presence of a magnetic resonance imaging (MRI) environment, the method comprising:
- receiving a therapy command from an external device while the IMD is in the presence of an MRI electromagnetic field and is operating in a first operational mode in which one or more sensors of the IMD have been disabled, the therapy command configured to prompt the IMD to provide immediate therapy to the patient while in the MRI electromagnetic field; and
placing the IMD in a second operational mode upon receiving the therapy command, wherein the second operational mode includes;
enabling the one or more sensors of the IMD;
determining whether a tachyarrhythmia is present using the one or more sensors; and
delivering antitachycardia pacing (ATP) therapy to the patient if a tachyarrhythmia is determined to be present, wherein shock therapy is not delivered by the IMD when in the second operational mode if tachyarrhythmia is determined to be present while the IMD is in the presence of the MRI electromagnetic field.
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Abstract
Systems and methods for arrhythmia therapy in MRI environments are disclosed. Various systems disclosed utilize ATP therapy rather than ventricular shocks when patients are subjected to electromagnetic fields in an MRI scanner bore and shock therapy is not available. As the patient is moved out from within the scanner bore and away from the MRI scanner, the magnetic fields diminish in strength eventually allowing a high voltage capacitor within the IMD to charge if necessary. The system may detect when the electromagnetic fields no longer interfere with the shock therapy and will transition the IMD back to a normal operational mode where shock therapy can be delivered. Then, if the arrhythmia still exists, the system will carry out all of the system'"'"'s prescribed operations, including the delivery of electric shocks to treat the arrhythmia.
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Citations
21 Claims
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1. A method for operating an implantable medical device (IMD) implanted within a patient in the presence of a magnetic resonance imaging (MRI) environment, the method comprising:
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receiving a therapy command from an external device while the IMD is in the presence of an MRI electromagnetic field and is operating in a first operational mode in which one or more sensors of the IMD have been disabled, the therapy command configured to prompt the IMD to provide immediate therapy to the patient while in the MRI electromagnetic field; and placing the IMD in a second operational mode upon receiving the therapy command, wherein the second operational mode includes; enabling the one or more sensors of the IMD; determining whether a tachyarrhythmia is present using the one or more sensors; and delivering antitachycardia pacing (ATP) therapy to the patient if a tachyarrhythmia is determined to be present, wherein shock therapy is not delivered by the IMD when in the second operational mode if tachyarrhythmia is determined to be present while the IMD is in the presence of the MRI electromagnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An implantable medical device (IMD) configured for implantation in a patient to monitor cardiac activity in, and deliver therapy to, the patient'"'"'s heart, the IMD comprising:
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a pulse generator operable to deliver pacing pulses and shock pulses; at least one lead having a proximal section coupled to the pulse generator and a distal section secured to the patient'"'"'s heart, wherein the at least one lead is configured to deliver a therapeutic stimulus to the patient'"'"'s heart; and a state control module operable to selectively place the IMD in any of a plurality of operational modes for operation of the IMD in the presence of an MRI electromagnetic field that is strong enough to interfere with operation of the IMD, wherein the IMD is configured to not deliver the shock pulses while in the presence of the MRI electromagnetic field and the operational modes include; a first operational mode where the IMD monitors for a therapy command from an external device indicating the need for immediate therapy, wherein the IMD is configured to not deliver the pacing pulses while in the first operational mode, a second operational mode that activates one or more sensors to be used in determining the presence of a tachyarrhythmia, wherein the IMD is configured to enter the second operational mode based on reception of the therapy command while in the first operational mode, and a third operational mode in which the IMD delivers the pacing pulses until the tachyarrhythmia is no longer determined to be present or until a fixed number of pacing sessions have been exhausted, wherein the IMD is configured to enter the third operational mode based on detecting the presence of the tachyarrhythmia in the second operational mode. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of operating an implantable medical device (IMD) in the presence of a magnetic resonance imaging (MRI) environment, the method comprising:
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monitoring for an MRI signal indicating the presence of a strong MRI electromagnetic field that could interfere with operation of the IMD; entering a first operational mode when the MRI signal is detected, wherein upon entering the first operational mode of the IMD at least one sensor input to the IMD is ignored and no pacing therapy or shock therapy is delivered to a patient'"'"'s heart; monitoring for a therapy command signal from an external device indicating the need for immediate therapy while the IMD is still in the presence of the MRI electromagnetic field and in the first operational mode; transitioning the IMD into a second operational mode upon detecting the therapy command signal while the IMD is still in the presence of the MRI electromagnetic field, wherein the at least one sensor input of the IMD is monitored to determine if a tachyarrhythmia exists while the IMD is in the second operational mode; and while the IMD is still in the second operational mode, delivering pacing therapy to the patient if a tachyarrhythmia is determined to be present while the IMD is still in the presence of the MRI electromagnetic field, wherein shock therapy is not delivered by the IMD if tachyarrhythmia is determined to be present while the IMD is still in the presence of the MRI electromagnetic field. - View Dependent Claims (19, 20, 21)
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Specification