Managing recharge power for implantable medical devices

Patent metadata

Field	Value
Publication number	US-11534614-B2
Application number	US-202016879159-A
Country	US
Kind code	B2
Filing date	May 20, 2020
Priority date	Jan 27, 2012
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

Devices, systems, and techniques for controlling charging power based on a cumulative thermal dose to a patient are disclosed. Implantable medical devices may include a rechargeable power source that can be transcutaneously charged. An external charging device may calculate an estimated cumulative thermal dose delivered to the patient during charging over a predetermined period of time. Based on the estimated cumulative thermal dose, the external charging device may select a power level for subsequent charging of the rechargeable power source. In one example, the charging device may select a high power level when the cumulative thermal dose has not exceeded a thermal dose threshold and select a low power level when the cumulative thermal dose has exceeded the thermal dose threshold.

First claim

The invention claimed is:

1. A system comprising:
processing circuitry configured to:
calculate an estimated cumulative thermal dose delivered to a patient during charging of a rechargeable power source of an implantable medical device over a period of time;
select, based on the estimated cumulative thermal dose, a power level for subsequent charging of the rechargeable power source; and
control a charging module to charge the rechargeable power source according to the selected power level.

2. The system of claim 1 , wherein to control the charging module to charge the rechargeable power source, the processing circuitry is configured to:
cause the charging module to generate a first electrical current in a primary coil based on the selected power level; and
cause the charging module to induce an electrical current in an implanted secondary coil associated with the rechargeable power source.

3. The system of claim 1 , wherein the period of time is one of selected from between approximately one hour and forty-eight hours or a single recharge session.

4. The device of claim 1 , wherein to select the power level, the processing circuitry is configured to:
select a high power level when the estimated cumulative thermal dose has not exceeded a thermal dose threshold; and
select a low power level when the estimated cumulative thermal dose has exceeded the thermal dose threshold.

5. The system of claim 1 , wherein to select the power level, the processing circuitry is configured to:
calculate an available thermal dose by subtracting the estimated cumulative thermal dose from a thermal dose threshold;
select a high power level when the available thermal dose is greater than a high power dose requirement; and
select a low power level when the available thermal dose is less than the high power dose requirement.

6. The system of claim 1 , wherein the processing circuitry is further configured to:
initiate a lockout period after controlling the charging module to charge the rechargeable power source with a high power level; and
control the charging module to prevent selection of the high power level during the lockout period and allow selection of a low power level during the lockout period, wherein a duration of the lockout period is based on a previous charging time with the high power level.

7. The system of claim 1 , wherein to calculate the estimated cumulative thermal dose, the processing circuitry is configured to calculate an integral of a tissue temperature over the period of time.

8. The system of claim 7 , wherein the processing circuitry is further configured to receive a signal indicative of the tissue temperature adjacent to the rechargeable power source.

9. The system of claim 7 , wherein the processing circuitry is further configured to calculate the tissue temperature based on a tissue model and power transmitted to the rechargeable power source over the period of time.

10. The system of claim 1 , wherein one of the implantable medical device or an external charging device comprises the processing circuitry.

11. The system of claim 1 , wherein the implantable medical device comprises a first portion of the processing circuitry, and wherein an external charging device comprises a second portion of the processing circuitry.

12. A method comprising:
calculating, by processing circuitry, an estimated cumulative thermal dose delivered to a patient during charging of a rechargeable power source of an implantable medical device over a period of time;
selecting, by the processing circuitry based on the estimated cumulative thermal dose, a power level for subsequent charging of the rechargeable power source; and
controlling, by the processing circuitry, a charging module to charge the rechargeable power source according to the selected power level.

13. The method of claim 12 , wherein controlling the charging module to charge the rechargeable power source comprises:
causing the charging module to generate a first electrical current in a primary coil based on the selected power level; and
causing the charging module to induce an electrical current in an implanted secondary coil associated with the rechargeable power source.

14. The method of claim 12 , wherein selecting the power level comprises:
selecting a high power level when the estimated cumulative thermal dose has not exceeded a thermal dose threshold; and
selecting a low power level when the estimated cumulative thermal dose has exceeded the thermal dose threshold.

15. The method of claim 12 , wherein selecting the power level comprises:
calculating an available thermal dose by subtracting the estimated cumulative thermal dose from a thermal dose threshold;
selecting a high power level when the available thermal dose is greater than a high power dose requirement; and
selecting a low power level when the available thermal dose is less than the high power dose requirement.

16. The method of claim 12 , wherein method further comprises:
initiating, by the processing circuitry, a lockout period after controlling the charging module to charge the rechargeable power source with a high power level; and
controlling, by the processing circuitry, the charging module to prevent selection of the high power level during the lockout period and allow selection of a low power level during the lockout period, wherein a duration of the lockout period is based on a previous charging time with the high power level.

17. The method of claim 12 , wherein calculating the estimated cumulative thermal comprises calculating an integral of a tissue temperature over the period of time.

18. The method of claim 17 , wherein the method further comprises receiving, by the processing circuitry, a signal indicative of the tissue temperature adjacent to the rechargeable power source.

19. The method of claim 17 , wherein the method further comprises calculating the tissue temperature based on a tissue model and power transmitted to the rechargeable power source over the period of time.

20. A computer-readable storage medium comprising instructions that cause processing circuitry to:
calculate an estimated cumulative thermal dose delivered to a patient during charging of a rechargeable power source of an implantable medical device over a period of time;
select, based on the estimated cumulative thermal dose, a power level for subsequent charging of the rechargeable power source; and
control a charging module to charge the rechargeable power source according to the selected power level.

Assignees

• Medtronic Inc

Inventors

• Kelly Kevin J
• Olson David P
• Bornhoft Reid K
• Gaddam Venkat R

Classifications

• F04C2270/041

  Controlled or regulated · CPC title

• A61N1/3787 Primary

  from an external energy source · CPC title