IMPLANTABLE MEDICAL DEVICE DEPTH ESTIMATION

• US 20140203823A1
• Filed: 01/18/2013
• Published: 07/24/2014
• Est. Priority Date: 01/18/2013
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: JOSHI, Himanshu
• Granted Patent: US 9,435,830 B2
• Time in Patent Office: Days
• US Class Current: 324/655
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence

Abstract

A method includes applying a signal to a primary coil of an external charging device. The signal causes the primary coil to inductively couple to a secondary coil of an implantable medical device that is implanted within tissue of a patient. The method also includes measuring a current at the primary coil. The method further includes estimating a depth of the implantable medical device within the tissue of the patient based on the measured current.

Claims

1. A method comprising:

applying a signal to a primary coil of an external charging device, wherein the signal causes the primary coil to inductively couple to a secondary coil of an implantable medical device that is implanted within tissue of a patient;

measuring a current at the primary coil; and

estimating a depth of the implantable medical device within the tissue of the patient based on the measured current.

2. The method of claim 1, wherein the depth is estimated further based on a dimension of the primary coil, a dimension of the secondary coil, or both.

3. The method of claim 1, wherein the signal is applied at a frequency that approximately corresponds to a resonant frequency of an inductive system including the primary coil and the secondary coil.

4. The method of claim 1, further comprising, when the depth is estimated to be greater than a threshold depth, notifying an operator that a charging cycle may be extended.

5. The method of claim 1, further comprising, when the depth is estimated to be less than a threshold depth, increasing a distance between the primary coil and the secondary coil.

6. The method of claim 5, wherein the threshold depth corresponds to a designed implant depth of the implantable medical device.

7. The method of claim 1, further comprising determining settings for a matching network of the implantable medical device based on the depth.

8. The method of claim 1, further comprising sending depth data to the implantable medical device, wherein the depth data indicates the depth.

9. The method of claim 8, wherein the implantable medical device adjusts a configuration of a matching network of the implantable medical device based on the depth data.

10. The method of claim 1, wherein the current at the primary coil is measured multiple times during a first charging period and wherein a lowest current value measured during the first charging period is used to estimate the depth.

11. A device comprising:

a primary coil configured to inductively couple to a secondary coil of an implantable medical device;

a current measurement device coupled to the primary coil and configured to measure a current applied to the primary coil while the secondary coil is inductively coupled to the primary coil; and

a processor coupled to the current measurement device, the processor configured to estimate a depth of the implantable medical device within tissue of a patient based on the measured current.

12. The device of claim 11, wherein the depth is estimated further based on a dimension of the primary coil, a dimension of the secondary coil, or both.

13. The device of claim 11, wherein the primary coil inductively couples to the secondary coil in response to a signal applied to the primary coil while the primary coil is in proximity to the secondary coil, and wherein the signal is applied at a frequency that approximately corresponds to a resonant frequency of an inductive system including the primary coil and the secondary coil.

14. The device of claim 11, further comprising a user interface device configured to provide a notification to an operator that a charging cycle may be extended when the depth is estimated to be greater than a threshold depth.

15. The device of claim 11, further comprising a depth adjustment apparatus that is movable to adjust a distance between the primary coil and the secondary coil.

16. The device of claim 11, wherein the processor is further configured to determine settings for a matching network of the implantable medical device based on the depth.

17. The device of claim 11, further comprising a transmitter responsive to the processor to send depth data to the implantable medical device, wherein the depth data indicates the depth, wherein the implantable medical device is configured to adjust a configuration of a matching network of the implantable medical device based on the depth data.

18. The device of claim 11, wherein the current measurement device is configured to measure the current at the primary coil multiple times during a first charging period and wherein the processor is configured to estimate the depth based on a lowest current value measured during the first charging period.

19. A computer readable storage device comprising instructions that, when executed by a processor, cause the processor to:

cause a primary coil of an external charging device to inductively couple to a secondary coil of an implantable medical device that is implanted within tissue of a patient; and

determine an estimated depth of the implantable medical device within the tissue of the patient based on a current measured at the external charging device.

20. The computer readable storage device of claim 19, further comprising instructions that, when executed by a processor, cause the processor to:

cause a current measurement device to measure the current at the primary coil multiple times during a first charging period and wherein the estimated depth is based on a lowest current value measured during the first charging period.