Method of tuning bandstop filters for implantable medical leads
First Claim
1. A process for tuning a TANK filter to attenuate RF current flow through the TANK filter due to electromagnetic energy induced onto an implantable lead in an MRI environment, comprising the steps of:
- providing a TANK filter having an inductor electrically connected in parallel with a capacitor;
measuring frequency attenuation of the TANK filter; and
modifying physical characteristics of the inductor and/or the capacitor until a resonant frequency of the TANK filter attenuates induced current flow at a pre-selected, center MRI RF pulsed frequency or range of MRI RF pulsed frequencies.
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Abstract
A TANK filter is provided for a lead wire of an active medical device (AMD). The TANK filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the TANK filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the TANK filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the TANK filter is integrated into a TIP and/or RING electrode for an active implantable medical device.
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Citations
19 Claims
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1. A process for tuning a TANK filter to attenuate RF current flow through the TANK filter due to electromagnetic energy induced onto an implantable lead in an MRI environment, comprising the steps of:
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providing a TANK filter having an inductor electrically connected in parallel with a capacitor; measuring frequency attenuation of the TANK filter; and modifying physical characteristics of the inductor and/or the capacitor until a resonant frequency of the TANK filter attenuates induced current flow at a pre-selected, center MRI RF pulsed frequency or range of MRI RF pulsed frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for tuning a TANK filter to attenuate RF current flow through the TANK filter due to electromagnetic energy induced onto an implantable lead in an MRI environment, comprising the steps of:
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providing a TANK filter having an inductor electrically connected in parallel with a capacitor; measuring frequency attenuation of the TANK filter; and modifying physical characteristics of the inductor and/or the capacitor until a resonant frequency of the TANK filter attenuates induced current flow at a pre-selected, center MRI RF pulsed frequency or range of MRI RF pulsed frequencies, and the TANK filter has an overall circuit Q wherein the resultant 3 dB bandwidth is on the order of MHZ. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification