DUAL FUNCTION TUNED L-C INPUT TRAP PASSIVE EMI FILTER COMPONENT NETWORK FOR AN ACTIVE IMPLANTABLE MEDICAL DEVICE

• US 20110043297A1
• Filed: 09/27/2010
• Published: 02/24/2011
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Dabney, Warren S., Kelley, Scott W., Stevenson, Robert A., Johnson, Robert Shawn
• Granted Patent: US 8,483,840 B2
• Time in Patent Office: Days
• US Class Current: 333/12
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• CPC Class Codes: A61B 2562/222 Electrical cables or leads therefor, e.g. coaxial cables or ribbon cables
• CPC Class Codes: A61B 2562/227 Sensors with electrical connectors
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/283 Invasive
• 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: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2007/013 Notch or bandstop filters

Abstract

Decoupling circuits are provided which transfer energy induced from an MRI pulsed RF field to the housing for an active implantable medical device (AIMD) which serves as an energy dissipating surface. A novel L-C input trap filter is provided which has a dual function. The L-C trap acts as a broadband low pass EMI filter while at the same time also acts as an L-C trap in order to divert induced RF energy from the lead to the housing of the AIMD.

Claims

1. A dual function passive component network for an active implantable medical device (AIMD), comprising:

an electromagnetically shielded AIMD housing;

at least one electronic sensing or therapy delivery circuit disposed within the AIMD housing;

a first conductive path having a series inductance, from the electronic circuit to a tissue-stimulating or biological sensing electrode at a distal end of an implantable lead; and

a second conductive path having a series capacitance, coupled between the first conductive path and the AIMD housing, wherein the capacitance provides at least one component of an electromagnetic interference (EMI) filter for the electronic circuit;

wherein the inductance and the capacitance form a frequency selective L-C trap for diverting high frequency energy induced on the first conductive path at a selected frequency or range of frequencies to the AIMD housing through the second conductive path.

2. The passive component network of claim 1, wherein the high frequency energy comprises an MRI RF pulsed frequency.

3. The passive component network of claim 2, wherein said MRI pulsed frequency comprises a range of MRI RF pulsed frequencies.

4. The passive component network of claim 3, wherein a center frequency of said range of MRI RF pulsed frequencies in megahertz is selected from the group of frequencies comprising the MRI constant times the static magnetic field strength in Teslas of an MRI scanner.

5. The passive component network of claim 1, wherein the EMI filter comprises at least one capacitor and at least one inductor.

6. The passive component network of any of claims 1 through 5, wherein the EMI filter comprises a low pass filter.

7. The passive component network of claim 6, wherein the low pass filter comprises an L-C filter, a T filter, an LL filter, or an “

n”

element filter.

8. The passive component network of claim 1, wherein the AIMD comprises an implantable hearing device, a neurostimulator, a brain stimulator, a cardiac pacemaker, a left ventricular assist device, an artificial heart, a drug pump, a bone growth stimulator, a urinary incontinence device, a spinal cord stimulator, an anti-tremor stimulator, an implantable cardioverter defibrillator, a congestive heart failure device, or a cardio resynchronization therapy device.

9. The passive component network of any of claims 1 through 4, wherein the series inductance of the first conductive path comprises at least one inductor.

10. The passive component network of claim 9, wherein the second conductive path is conductively coupled to the first conductive path between the inductor and the electronic circuit.

11. The passive component network of claim 10, wherein the series capacitance of the second conductive path comprises at least one capacitor.

12. The passive component network of claim 11, wherein the capacitor comprises a feedthrough capacitor.

13. The passive component network of claim 12, wherein the feedthrough capacitor is associated with a hermetic terminal through which the first conductive path extends in non-conductive relation with the AIMD housing.

14. The passive component network of claim 13, wherein the inductor is disposed exteriorly of the AIMD housing.

15. The passive component network of claim 14, wherein the inductor is disposed within a header block for the AIMD.

16. The passive component network of claim 14, wherein the inductor has external surfaces comprised entirely of biocompatible and non-migratable materials.

17. The passive component network of claim 11, wherein the inductor and the capacitor are both disposed within the AIMD housing.

18. The passive component network of claim 17, wherein the inductor comprises a chip inductor, a circuit trace, a toroidal inductor, or a solenoid inductor.

19. The passive component network of claim 17, wherein the capacitor comprises a chip capacitor or parasitic capacitance.

20. The passive component network of claim 11, including at least one additional passive network component disposed in-circuit between the L-C trap and the electronic circuit.

21. The passive component network of claim 20, wherein the at least one additional passive network component comprises a low pass filter, a bandstop filter, or an L-C trap.