Band stop filter employing a capacitor and an inductor tank circuit to enhance MRI compatibility of active implantable medical devices

• US 7,363,090 B2
• Filed: 05/01/2007
• Issued: 04/22/2008
• Est. Priority Date: 04/13/2001
• Status: Expired due to Fees

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Stevenson, Robert A., Halperin, Henry R.
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): Wu; Eugene T
• Application Number:
  US11/743,000
• Publication Number:
  US 20070288058A1
• Time in Patent Office: 357 Days
• Field of Search: 333/172, 333/175, 333/176, 600/411, 607/2, 607/6, 607/37, 607/63, 607/116, 607/121
• US Class Current: 607/116
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/287 involving active visualization of interventional instruments, e.g. using active tracking RF coils or coils for intentionally creating magnetic field inhomogeneities
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2007/013 Notch or bandstop filters
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence
• CPC Class Codes: Y10T 29/49169 Assembling electrical component directly to terminal or elongated conductor

Abstract

A band stop filter is provided for a lead wire of an active implantable medical device (AIMD). The band stop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the implantable lead wire of the AIMD, wherein values of capacitance and inductance are selected such that the band stop 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 band stop filter to attenuate current flow through the implantable lead wire along a range of selected frequencies. In a preferred form, the band stop filter is integrated into a TIP and/or RING electrode for the active implantable medical device.

Claims

1. A band stop filter for an implantable lead wire of an active implantable medical device, which comprises:

a) a lead wire having a length extending between and to a proximal end and a distal end; and

b) at least one band stop filter comprising a capacitor in parallel with an inductor, said parallel capacitor and inductor combination placed in series with the lead wire somewhere along the length between and to the proximal end and the distal end of the lead wire wherein values of capacitance and inductance have been selected such that the band stop filter is resonant at a selected frequency and further wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency versus frequency band width characteristics.

2. The band stop filter of claim 1, wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.

3. The band stop filter of claim 2, wherein the inductor has a relatively low resistive loss;

and wherein the capacitor has a relatively high equivalent series resistance.

4. The band stop filter of claim 3, wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wire along a range of selected frequencies.

5. The band stop filter of claim 4, wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.

6. The band stop filter of claim 1, wherein the band stop filter is disposed adjacent to a distal tip of the lead wire.

7. The band stop filter of claim 6, wherein the band stop filter is integrated into a selected one of a TIP electrode and a RING electrode.

8. A band stop filter for a medical diagnostic or therapeutic device comprising an active implantable medical device and an implantable lead wire having a length extending therefrom between and to a proximal end and a distal end and adapted to be in contact with biological cells, the band stop filter comprising:

at least one a band stop filter associated with the lead wire, for attenuating current flow through the lead wire at a selected frequency, wherein the band stop filter comprises a capacitor in parallel with an inductor, said parallel capacitor and inductor placed in series with the lead wire somewhere along the length between and to the proximal end and the distal end of the lead wire, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at the selected frequency.

9. The band stop filter of claim 8, wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.

10. The band stop filter of claim 9, wherein the inductor has a relatively low resistive loss.

11. The band stop filter of claim 9, wherein the capacitor has a relatively high equivalent series resistance.

12. The band stop filter of claim 9, wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wire along a range of selected frequencies.

13. The band stop filter of claim 12, wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.

14. The band stop filter of claim 8, wherein the band stop filter is disposed adjacent to the distal tip of the implantable lead wire.

15. The band stop filter of claim 14, wherein the band stop filter is integrated into a selected one of a TIP electrode and a RING electrode.

16. The band stop filter of claim 15, wherein the overall Q of the band stop filter is selected to attenuate current flow through the implantable lead wire along a range of selected frequencies.

17. The band stop filter of claim 8, wherein the active implantable medical device, comprises cochlear implants, piezoelectric sound bridge transducers, neurostimulators, brain stimulators, cardiac pacemakers, ventricular assist devices, artificial hearts, drug pumps, bone growth stimulators, bone fusion stimulators, urinary incontinence devices, pain relief spinal cord stimulators, anti-tremor stimulators, gastric stimulators, implantable cardioverter defibrillators, pH probes, congestive heart failure devices, neuromodulators, cardiovascular stents, and orthopedic implants.

18. The band stop filter of claim 8, wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency versus frequency band width characteristics.