Simulation of magnetic field induced vibrations in implantable medical devices

• US 7,383,734 B2
• Filed: 01/31/2006
• Issued: 06/10/2008
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Hiller, Robert, Nath, Bijoyendra, Garcia, Kateri A., Wiklund, Craig L., Neville, James D., Jenison, Troy A.
• Primary Examiner(s): Winakur; Eric F.
• Assistant Examiner(s): Bor; Helene
• Application Number:
  US11/342,912
• Publication Number:
  US 20070176596A1
• Time in Patent Office: 861 Days
• Field of Search: 600/411, 434/262, 324/318, 736/62, 736/49, 74/1.SS
• US Class Current: 73/668
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 2/00 Magnetotherapy

Abstract

A mechanical response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate is simulated by exposing the IMD to a second static magnetic field having a magnitude greater than the first static magnetic field and generating a second gradient magnetic field at the IMD such that a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to a product of the first static magnetic field and the first gradient magnetic field slew rate.

Claims

1. A method for simulating a mechanical response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate, the method comprising:

exposing the IMD to a second static magnetic field having a magnitude greater than the first static magnetic field;

generating a second gradient magnetic field at the IMD, wherein a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to or greater than a product of the first static magnetic field and the first gradient magnetic field slew rate;

storing data related to the mechanical response produced by the second static and gradient magnetic fields; and

reproducing the mechanical response based on the stored data.

2. The method of claim 1, wherein the second static magnetic field is at least about 4.0 T.

3. The method of claim 1, wherein the product of the second static magnetic field and the second gradient magnetic field slew rate is at least about 150 T²/s.

4. A method for testing a vibration response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate, the method comprising:

simulating the vibration response by disposing the IMD in a second static magnetic field having a magnitude greater than the first static magnetic field and generating a second gradient magnetic field at the IMD such that a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to or greater than a product of the first static magnetic field and the first gradient magnetic field slew rate; and

sensing the vibration response of a plurality of components within the the IMD to the second static magnetic field and the second gradient magnetic field.

5. The method of claim 4, wherein the sensing step comprises measuring relative motion between components of the IMD.

6. The method of claim 5, wherein measuring relative motion between components of the IMD comprises at least one of measuring a relative velocity between the components, measuring a relative acceleration between of the components, and measuring a relative displacement between the components.

7. The method of claim 4, and further comprising:

measuring a magnitude of the vibration response to the second gradient magnetic field at various frequencies.

8. The method of claim 4, and further comprising:

mechanically reproducing the vibration response to test other IMDs.

9. The method of claim 4, wherein the second static magnetic field is at least about 4.0 T.

10. The method of claim 4, wherein the product of the second static and gradient magnetic fields is at least about 150 T²/s.

11. A method for testing a reliability of a plurality of implantable medical devices (IMDs) in a magnetic resonance imaging (MRI) scanner that generates a first static magnetic field and a first gradient magnetic field, the method comprising:

exposing an IMD in a second static magnetic field having a magnitude greater than the first static magnetic field;

generating a second gradient magnetic field at the IMD, wherein a product of the second static and gradient magnetic fields is substantially equal to or greater than a product of the first static and gradient magnetic fields;

characterizing a mechanical vibratory response of a plurality of components of the IMD to the second static magnetic field and the second gradient magnetic field; and

reproducing the characterized mechanical vibratory response on the plurality of IMDs.

12. The method of claim 11, wherein the mechanical response is reproduced by a mechanical vibrator.

13. The method of claim 11, wherein the characterizing step comprises measuring relative motion between components of the IMD.

14. The method of claim 13, wherein measuring relative motion between components of the IMD comprises at least one of measuring a relative velocity between the components, measuring a relative acceleration between of the components, and measuring a relative displacement between the components.

15. The method of claim 11, wherein the characterizing step comprises measuring a magnitude of the mechanical response to the second gradient magnetic field at various frequencies.

16. The method of claim 11, and further comprising:

testing a functionality of the IMDs after reproducing the characterized mechanical response on the plurality of IMDs.

17. The method of claim 11, wherein the second static magnetic field is at least about 4.0 T.

18. The method of claim 11, wherein the product of the second static and gradient magnetic fields is at least about 150 T²/s.