TANK FILTERS UTILIZING VERY LOW K MATERIALS, IN SERIES WITH LEAD WIRES OR CIRCUITS OF ACTIVE MEDICAL DEVICES TO ENHANCE MRI COMPATIBILITY

• US 20080071313A1
• Filed: 09/24/2007
• Published: 03/20/2008
• Est. Priority Date: 11/11/2005
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Stevenson, Robert, Frysz, Christine, Dabney, Warren, Brendel, Richard
• Granted Patent: US 7,853,324 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/0565 Electrode heads
• CPC Class Codes: A61N 1/0573 chacterised by means penetrating the heart tissue, e.g. helix needle or hook
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: A61N 1/3752 Details of casing-lead connections
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01F 17/06 with core substantially closed in itself, e.g. toroid
• CPC Class Codes: H01F 27/40 Structural association with built-in electric component, e.g. fuse
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2001/005 Wound, ring or feed-through type inductor
• CPC Class Codes: H03H 2001/0078 comprising spiral inductor on a substrate
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence

Abstract

A TANK filter is provided for a lead wire of an active medical device (AMD). In a preferred form, the TANK filter is integrated into a TIP and/or RING electrode for an active implantable medical device. 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 to attenuate current flow through the lead wire along a range of selected frequencies. In a particularly preferred form, the TANK filter is manufactured using very low k materials of sufficient strength to handle forces applied thereto during installation and use.

Claims

1. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter comprising a low k substrate material, placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band.

2. The device of claim 1, wherein the substrate material has a k value of 200 or less.

3. The device of claim 2, wherein the substrate material comprises a ceramic dielectric material.

4. The device of claim 3, wherein the dielectric material is selected from:

NPO, porcelain, glass, or alumina ceramic.

5. The device of claim 1, wherein the selected frequency band comprises an MRI pulsed frequency.

6. The device of claim 1, wherein the tank filter comprises an inductor placed in parallel with a capacitor, wherein the capacitance and inductance values are selected such that the tank filter attenuates circuit flow at the selected frequency band.

7. The device of claim 6, wherein the capacitor includes a first set of embedded electrode plates extending to a first metallization surface, and a second set of embedded electrode plates extending to a second surface metallization, the inductor being electrically connected to the first and second surface metallizations.

8. The device of claim 6, wherein the tank filter comprises a tubular capacitor electrically connected to the electrode and the lead wire, and an inductor in parallel with the capacitor and electrically connected to the lead wire and the electrode.

9. The device of claim 8, wherein the inductor is disposed within the capacitor.

10. The device of claim 9, wherein the inductor comprises a spiral wound inductor or a chip inductor.

11. The device of claim 1, wherein the tank filter comprises:

a tubular capacitor electrically connected to the conductor and the electrode;

an inductor comprising a spiral winding around a ferro-magnetic core disposed within the capacitor and electrically connected to the conductor and the electrode;

and

a sleeve disposed over the inductor for creating a ferro-magnetic field to reduce or prevent saturation of the inductor in the presence of a static magnetic field.

12. The device of claim 1, wherein the tank filter comprises a circuit trace disposed on a capacitor substrate of low k material or a substrate of low k material attached to the capacitor so as to be in parallel therewith.

13. The device of claim 12, wherein the circuit trace includes multiple turns over the length thereof.

14. The device of claim 1, wherein the tank filter comprises a capacitor having an inductor trace embedded within the low k substrate material thereof so as to be in parallel therewith.

15. The device of claim 1, wherein the tank filter comprises a feedthrough capacitor having a parallel inductor circuit trace disposed thereon or embedded therein, and wherein the lead wire is electrically connected to a contact plate electrically connected to a first metallization surface of the capacitor, and the electrode is electrically connected to a second metallization of the capacitor.

16. The device of claim 1, wherein the tank filter is hermetically sealed from body fluids.

17. The device of claim 16, wherein the tank filter is encapsulated in a hermetically sealing material or disposed within a hermetically sealed housing.

18. The device of claim 1, wherein the tank filter comprises a set of low k substrates in stacked relation, at least a plurality of the substrates having inductor traces on a surface thereof, and wherein the inductor traces are electrically interconnected with one another.

19. The device of claim 1, wherein the conductor comprises a coiled lead wire for connecting the electrode to the electronic circuitry, and wherein the tank filter comprises a chip capacitor comprised of a low k dielectric material, having wire bond pads disposed within, and electrically connected to, the coiled lead wire.

20. The device of claim 1, including a plurality of tank filters placed in series with the conductor, each tank filter having electrical inductance in parallel with capacitance, wherein each tank filter attenuates current flow at a different selected frequency band.

21. The device of claim 1, wherein the electrode comprises a high surface area distal TIP electrode, or an active fixation helix TIP electrode.

22. The device of claim 21, wherein the electrode comprises the active fixation distal TIP electrode having a spline electrically connected to the electrical conductor and extending within a housing having a coiled helix TIP therein, the tank filter being disposed within the housing and electrically connected to the spline and the coiled helix.

23. The device of claim 1, wherein the active medical device comprises a bion, an EKG device, or an EEG device.

24. The device of claim 1, wherein the medical device electrode comprises a neurostimulation TIP, an ablation probe, or a catheter.