Systems and Methods for Selecting Components for Use in RF Filters Within Implantable Medical Device Leads Based on Inductance, Parasitic Capacitance and Parasitic Resistance
First Claim
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19. A lead for use with an implantable medical device subject to radio-frequency (RF) fields, the lead comprising:
- an electrode;
a conductor connected to the electrode; and
an inductive filtering element connected along the conductor, wherein the filtering element includes an inductor achieving a target impedance at a particular frequency to be filtered, the inductor having an inductance and a parasitic capacitance, and wherein the inductance and parasitic capacitance are sufficient to achieve a target impedance value at the particular frequency despite variations in the inductance and parasitic capacitance due to device tolerance.
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Abstract
Techniques are provided for selecting and configuring inductors for use in radio-frequency (RF) inductive filters within pacing/sensing leads of pacemakers or implantable cardioverter-defibrillators. The filters are employed to reduce heating due to induced currents caused by magnetic resonance imaging (MRI) procedures or other sources of strong RF fields. In particular, techniques are provided for determining optimal inductance values by taking into account parasitic resistances and parasitic capacitances of the inductors. Tolerances of the inductive devices are also taken into account.
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Citations
27 Claims
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19. A lead for use with an implantable medical device subject to radio-frequency (RF) fields, the lead comprising:
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an electrode; a conductor connected to the electrode; and an inductive filtering element connected along the conductor, wherein the filtering element includes an inductor achieving a target impedance at a particular frequency to be filtered, the inductor having an inductance and a parasitic capacitance, and wherein the inductance and parasitic capacitance are sufficient to achieve a target impedance value at the particular frequency despite variations in the inductance and parasitic capacitance due to device tolerance.
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20. A method for designing a lead for use with an implantable medical device, wherein the lead includes an inductive filtering element to reduce lead heating due to radio-frequency (RF) fields, the inductive filtering element having an inductance and a parasitic capacitance, the method comprising:
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selecting a self-resonant frequency (SRF) between at least two separate RF signal frequencies of a magnetic resonance imaging (MRI) system and selecting a target impedance to be achieved at each of the selected frequencies; determining suitable values for inductance and parasitic capacitance sufficient to achieve the target impedance at each of the separate frequencies; and selecting and installing particular components for use in the inductive filtering element based, in part, on the suitable values for inductance and parasitic capacitance. - View Dependent Claims (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 23, 24, 25, 26)
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27. A lead for use with an implantable medical device subject to radio-frequency (RF) fields at a plurality of separate frequencies of a magnetic resonance imaging (MRI) system, the lead comprising:
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an electrode; a conductor connected to the electrode; and an inductive filtering element connected along the conductor, wherein the filtering element includes an inductor achieving a target impedance at each of the plurality of separate RF signal frequencies, the inductor having an inductance and a parasitic capacitance providing a self-resonant frequency between the separate RF signal frequencies, and wherein the inductance and parasitic capacitance are sufficient to achieve the target impedance value at each of the separate RF signal frequencies.
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Specification