Lead electrode for use in an MRI-safe implantable medical device

• US 20050222647A1
• Filed: 11/03/2004
• Published: 10/06/2005
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Olsen, James M., Wahlstrand, Carl D., Hrdlicka, Gregory A., Hoegh, Thomas Barry, Cross, Thomas E. Jr.
• Granted Patent: US 7,174,219 B2
• Time in Patent Office: Days
• US Class Current: 607/72
• 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 1/0529 Electrodes for brain stimulation
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/0553 Paddle shaped electrodes, e.g. for laminotomy
• CPC Class Codes: A61N 1/06 for high-frequency therapy
• 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

Abstract

A pulse stimulation system configured for implantation into a patient'"'"'s body comprises a pulse stimulator, a conductive stimulation lead having a proximal end electrically coupled to the pulse simulator and having a distal end, and an electrode assembly coupled to the distal end of the stimulation lead. The electrode assembly comprises an electrode body having a therapy electrode thereon that is electrically coupled to the stimulation lead for delivering therapy to the patient. A floating electrode is configured to contact the patient'"'"'s body tissue and has a surface area substantially larger than that of the therapy electrode. A filter is coupled between the therapy electrode and the floating electrode for diverting RF energy toward the floating electrode and away from the therapy electrode.

Claims

1. An electrode assembly for use in a pulse stimulation system configured to be implanted in a patient'"'"'s body and of the type that includes a pulse generator and a stimulation lead having a proximal end electrically coupled to the pulse generator and having a distal region, the electrode assembly comprising:

a paddle-shaped electrode body having first and second substantially opposite sides, the body coupled to the distal region of the stimulation lead;

at least one electrode on said first side and electrically coupled to the stimulation lead for delivering therapy to the patient;

a floating electrode on said second side and configured to contact patient body tissue; and

a filter coupled between said at least one electrode and said floating electrode for diverting RF energy toward said floating electrode and away from said at least one electrode.

2. An electrode assembly according to claim 1 wherein said RF energy is induced during an MRI scan.

3. An electrode assembly according to claim 1 wherein the RF energy is substantially diverted at frequencies between approximately 43 MHz to 215 MHz.

4. An electrode assembly according to claim 3 wherein said filter is a high-pass filter.

5. An electrode assembly according to claim 4 wherein said filter is a band-pass filter.

6. An electrode assembly according to claim 3 wherein the surface area of said floating electrode is at least an order of magnitude greater than that of said at least one electrode.

7. An electrode assembly according to claim 6 wherein the surface area of said floating electrode is at least approximately 120 square millimeters.

8. An electrode assembly according to claim 1 wherein the stimulation lead includes at least one conductive filer and said filter comprises at least one capacitor coupled between said at least one filer and said floating electrode.

9. An electrode assembly according to claim 8 wherein said capacitor has a capacitance in the range of 200 pF to 47,000 pF.

10. An electrode assembly according to claim 9 wherein said capacitor has a capacitance of approximately 1000 pF.

11. An electrode assembly according to claim 10 wherein said floating electrode comprises a conductive mesh.

12. An electrode assembly according to claim 11 wherein said conductive mesh is configured to have at least a portion thereof imbedded in said electrode body.

13. An electrode assembly according to claim 12 wherein said electrode body is a flexible polymer.

14. An electrode assembly according to claim 11 wherein said capacitor is coupled between said conductive mesh and said conductive filer proximal of said at least one electrode.

15. An electrode assembly according to claim 14 wherein said capacitor is coupled to said conductive mesh and to said conductive filer by crimping.

16. An electrode assembly according to claim 14 wherein said capacitor is coupled to said conductive mesh and to said conductive filer by welding.

17. An electrode assembly according to claim 16 wherein said capacitor is coupled to said conductive mesh by means of a conductive adhesive.

18. An electrode assembly according to claim 11 further comprising a dielectric material disposed between said at least one electrode and said conductive mesh.

19. An electrode assembly according to claim 18 wherein said dielectric material is tantalum oxide.

20. An electrode assembly according to claim 18 further comprising a capacitor plate coupled between said dielectric material and said conductive mesh.

21. An electrode assembly according to claim 14 further comprising an impedance mismatch component in the conduction path of said stimulation lead.

22. An electrode assembly according to claim 14 wherein said impedance mismatch component is coupled between said at least one electrode and said capacitor.

23. An electrode assembly according to claim 22 wherein said impedance mismatch component is an inductor.

24. A pulse stimulation system configured for implantation into a patient'"'"'s body, the system comprising:

a pulse generator;

a conductive stimulation lead having a proximal end electrically coupled to said pulse generator and having a distal end; and

an electrode assembly coupled to said distal end and comprising;

a paddle-shaped electrode body having first and second substantially opposite sides, the body coupled to said distal end of said stimulation lead;

at least one electrode on said first side and electrically coupled to said stimulation lead for delivering therapy to the patient;

a floating electrode on said second side and configured to contact patient body tissue; and

a filter coupled between said at least one electrode and said floating electrode for diverting RF energy toward said floating electrode and away from said at least one electrode.

25. An electrode assembly according to claim 24 wherein said RF energy is induced during an MRI scan.

26. An electrode assembly according to claim 24 wherein the RF energy is substantially diverted at frequencies between approximately 43 MHz to 215 MHz.

27. An electrode assembly according to claim 26 wherein said filter is a high-pass filter.

28. An electrode assembly according to claim 27 wherein said filter is a band-pass filter.

29. An electrode assembly according to claim 27 wherein the surface area of said floating electrode is at least an order of magnitude greater than that of said at least one electrode.

30. An electrode assembly according to claim 27 wherein said stimulation lead includes at least one conductive filer and said high-pass filter comprises at least one capacitor coupled between said at least one filer and said floating electrode.

31. An electrode assembly according to claim 30 wherein said capacitor has a capacitance in the range of 200 pF to 47,000 pF.

32. An electrode assembly according to claim 31 wherein said floating electrode comprises a conductive mesh.

33. An electrode assembly according to claim 32 wherein said conductive mesh is configured to have at least a portion thereof imbedded in said electrode body.

34. An electrode assembly according to claim 32 wherein said capacitor is coupled between said conductive mesh and said conductive filer proximal of said at least one electrode.

35. An electrode assembly according to claim 32 further comprising a dielectric material disposed between said at least one electrode and said conductive mesh.

36. An electrode assembly according to claim 35 wherein a capacitor plate is coupled between said dielectric material and said conductive mesh.

37. An electrode assembly according to claim 34 further comprising an impedance mismatch component coupled between said at least one electrode and said capacitor.

38. An electrode assembly according to claim 37 wherein said impedance mismatch component is an inductor.

39. An electrode assembly for use in a pulse stimulation system configured to be implanted in a patient'"'"'s body and of the type that includes a pulse generator and a stimulation lead having a proximal end electrically coupled to the pulse generator and having a distal end, the electrode assembly comprising:

a paddle-shaped electrode body coupled to the distal end of the stimulator lead, said electrode body having first and second sides;

at least one conductive filer within the stimulation lead and electrically coupled to the pulse generator;

at least one electrode positioned on said first side and coupled to said filer and configured to deliver therapy to the patient;

a conductive mesh positioned on said second side and configured to contact the patient'"'"'s body tissue; and

a high-pass filter coupled between said at least one electrode and said conductive mesh for diverting RF energy toward said conductive mesh and away from said at least one electrode.

40. An electrode assembly according to claim 39 wherein said RF energy is induced during an MRI scan.

41. An electrode assembly according to claim 39 wherein the RF energy is substantially diverted at frequencies between approximately 43 MHz to 215 MHz.

42. An electrode assembly according to claim 39 wherein the surface area of said conductive mesh is at least an order of magnitude greater than that of said at least one electrode.

43. An electrode assembly according to claim 42 wherein said high-pass filter comprises at least one capacitor coupled between said conductor mesh and said filer.

44. An electrode assembly according to claim 43 wherein said capacitor has a capacitance in the range of 200 pF to 47,000 pF.

45. An electrode assembly according to claim 44 wherein said conductive mesh is configured to have at least a portion thereof imbedded in said electrode body.

46. An electrode assembly according to claim 42 further comprising a dielectric material disposed between said at least one electrode and said conductive mesh.

47. An electrode assembly according to claim 46 wherein a capacitor plate is coupled between said dielectric material and said conductive mesh.

48. An electrode assembly according to claim 43 further comprising an inductor coupled between said capacitor and said at least one electrode.

49. An electrode assembly for use in a pulse stimulation system configured to be implanted in a patient'"'"'s body and of the type that includes a pulse generator and a stimulation lead having a proximal end electrically coupled to the pulse generator and having a distal region, the electrode assembly comprising:

a paddle-shaped electrode body having first and second substantially opposite sides, the body coupled to the distal region of the stimulation lead;

at least one electrode within said body and electrically coupled to the stimulation lead, said at least one electrode having a first side for delivering therapy to the patient and having a second side; and

alternating layers of conducting and non-conducting material stacked on said second side to capacitively couple said electrode to the patient'"'"'s body tissue for diverting RF energy to the patient'"'"'s body tissue.

50. An electrode assembly according to claim 49 wherein a first one of said alternating layers is in contact with said second side and at least one of said alternating layers is configured for contact with the patient'"'"'s body tissue.

51. An electrode assembly according to claim 50 wherein said last one is conductive.

52. An electrode assembly according to claim 50 wherein said last one is non-conducting and further comprising a floating electrode coupled to said last one and configured for contact with the patient'"'"'s body tissue.

53. An electrode assembly according to claim 50 wherein said RF energy is induced during an MRI scan.

54. An electrode assembly according to claim 50 wherein the RF energy is substantially diverted at frequencies between approximately 43 MHz to 215 MHz.

55. An electrode assembly according to claim 52 wherein said floating electrode comprises a conductive mesh.

56. An electrode assembly for use in a pulse stimulation system configured to be implanted in a patient'"'"'s body and of the type that includes a pulse generator and a stimulation lead having a proximal end electrically coupled to the pulse generator and having a distal region, the electrode assembly comprising:

a paddle-shaped electrode body having first and second substantially opposite sides, the body coupled to the distal region of the stimulation lead;

at least one electrode within said body and electrically coupled to the stimulation lead, said electrode having a first side for delivering therapy to the patient, and said electrode having a second side; and

a layer of dielectric material on said second side and configured to capacitively couple said electrode to the patient'"'"'s body for diverting RF energy to the patient'"'"'s body.

57. An electrode assembly according to claim 56 wherein said RF energy is induced during an MRI scan.

58. An electrode assembly according to claim 56 wherein the RF energy is substantially diverted at frequencies between approximately 43 MHz to 215 MHz.

59. An electrode assembly according to claim 56 wherein said dielectric material is a non-conductive polymer.

60. An electrode assembly according to claim 59 wherein said dielectric material is silicone.

61. An electrode assembly according to claim 56 wherein said dielectric material is tantalum oxide.