Medical leads with frequency independent magnetic resonance imaging protection
First Claim
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1. An elongate lead assembly configured to operatively couple with an implantable medical device for delivering a therapy pulse from the implantable medical device to a patient in an environment of a changing magnetic field, the lead assembly comprising:
- a conductive wire having a proximal end proximate the implantable medical device and a distal end opposite the proximal end;
an electrode coupled proximate the distal end of the conductive wire and configured to deliver the therapy pulse to the patient; and
an electrical circuit operatively coupled to the conductive wire, wherein the electrical circuit is configured to;
pass current in a first direction from the proximal end to the distal end of the conductive wire when a first voltage having a magnitude above a first voltage threshold is applied across the electrical circuit in the first direction positively biasing the electrical circuit in the first direction by the changing magnetic field; and
pass current in a second direction opposite the first direction when a second voltage having a magnitude above a second voltage threshold is applied across the electrical circuit in the second direction by the changing magnetic field but substantially blocking current in the second direction when a voltage less than the second voltage threshold is applied across the electrical circuit in the second direction negatively biasing the electrical circuit in the first direction by the changing magnetic field.
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Abstract
A medical device having a frequency independent circuit that substantially reduces induced currents in a lead assembly and at a tissue interface. The frequency independent circuit configures an electrical path such that a stimulation pulse travels from the medical device to a selected tissue, and a current induced by an external changing electromagnetic signal is prevented from travelling the electrical path from the selected tissue to the medical device.
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Citations
13 Claims
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1. An elongate lead assembly configured to operatively couple with an implantable medical device for delivering a therapy pulse from the implantable medical device to a patient in an environment of a changing magnetic field, the lead assembly comprising:
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a conductive wire having a proximal end proximate the implantable medical device and a distal end opposite the proximal end; an electrode coupled proximate the distal end of the conductive wire and configured to deliver the therapy pulse to the patient; and an electrical circuit operatively coupled to the conductive wire, wherein the electrical circuit is configured to; pass current in a first direction from the proximal end to the distal end of the conductive wire when a first voltage having a magnitude above a first voltage threshold is applied across the electrical circuit in the first direction positively biasing the electrical circuit in the first direction by the changing magnetic field; and pass current in a second direction opposite the first direction when a second voltage having a magnitude above a second voltage threshold is applied across the electrical circuit in the second direction by the changing magnetic field but substantially blocking current in the second direction when a voltage less than the second voltage threshold is applied across the electrical circuit in the second direction negatively biasing the electrical circuit in the first direction by the changing magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An elongate lead assembly configured to operatively couple with an implantable medical device for delivering a therapy pulse from the implantable medical device to a patient in an environment of a changing magnetic field, the lead assembly comprising:
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a conductive wire having a proximal end proximate the implantable medical device and a distal end opposite the proximal end; an electrode coupled proximate the distal end of the conductive wire and configured to deliver the therapy pulse to the patient; and a Zener diode operatively coupled to the conductive wire, wherein the Zener diode is configured to; pass current in a first direction from the proximal end to the distal end of the conductive wire when a first voltage having a magnitude above a first voltage threshold is applied across the Zener diode in the first direction positively biasing the Zener diode in the first direction by the changing magnetic field; and pass current in a second direction opposite the first direction when a second voltage having a magnitude above a second voltage threshold is applied across the Zener diode in the second direction by the changing magnetic field but substantially blocking current in the second direction when a voltage less than the second voltage threshold is applied across the Zener diode in the second direction negatively biasing the Zener diode in the first direction by the changing magnetic field. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification