Model reference identification and cancellation of magnetically-induced voltages in a gradient magnetic field
First Claim
1. A method of dynamically controlling an implanted medical device located within a patient'"'"'s body in the presence of a magnetic resonance imaging (MRI) field, the method comprising:
- detecting the presence of an MRI field within the body;
measuring the response of an excitation voltage or current applied to an implantable lead in the presence of the MRI field;
comparing the measured response obtained in the presence of the MRI field with a predicted response outputted by a lead and tissue reference model, the model including one or more model parameters stored within a memory unit for modeling the lead and body tissue within the body; and
dynamically modifying a voltage or current applied to the lead based at least in part on the predicted response outputted by the model.
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Abstract
Systems and methods of dynamically controlling an implanted medical device located within a patient'"'"'s body in the presence of a gradient magnetic field or other external interference are disclosed. The system can include a reference model of the implanted medical device and of body tissue within the patient'"'"'s body in the absence of a gradient magnetic field, and a control unit configured to dynamically control voltages or currents applied to a lead of the implanted medical device based on predicted parameters determined by the reference model.
335 Citations
19 Claims
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1. A method of dynamically controlling an implanted medical device located within a patient'"'"'s body in the presence of a magnetic resonance imaging (MRI) field, the method comprising:
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detecting the presence of an MRI field within the body; measuring the response of an excitation voltage or current applied to an implantable lead in the presence of the MRI field; comparing the measured response obtained in the presence of the MRI field with a predicted response outputted by a lead and tissue reference model, the model including one or more model parameters stored within a memory unit for modeling the lead and body tissue within the body; and dynamically modifying a voltage or current applied to the lead based at least in part on the predicted response outputted by the model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of dynamically controlling an implanted medical device located within a patient'"'"'s body in the presence of a gradient magnetic resonance imaging (MRI) field, the method comprising:
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measuring the response of an excitation voltage or current applied to a lead implanted in or near the heart in the absence of a gradient MRI field; creating a model of the implanted lead and of body tissue within the body, the model including one or more impedance parameters stored within a memory unit for modeling the implanted lead and the body tissue within the body; comparing the measured response in the absence of the gradient MRI field to an anticipated response generated by the model and outputting an error signal; adjusting one or more of the model parameters to minimize the error signal; detecting the presence of a gradient MRI field within the body; measuring the response of an excitation voltage or current applied to the lead in the presence of the gradient MRI field; comparing the measured response obtained in the presence of the gradient MRI field with a predicted response outputted by the model; and modifying a voltage or current applied to the lead based at least in part on the predicted response from the model. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification