USING TELEMETRY COUPLING AS A SURROGATE FOR RECHARGER COUPLING

• US 20090259273A1
• Filed: 04/10/2008
• Published: 10/15/2009
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Toy, Alex C., Figueiredo, Giselle Suraya, Widman, Erik G., Forsberg, John W., Keacher, Jeffrey T.
• Granted Patent: US 8,509,909 B2
• Time in Patent Office: Days
• US Class Current: 607/32
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

Techniques for using telemetry signal strength for positioning a primary recharge coil of a recharging unit at a location proximate to an Implantable Medical Device (IMD) in preparation to recharge a rechargeable power source of the IMD are disclosed. An antenna of the recharging unit is positioned proximate to the IMD, a telemetry session is initiated between the two devices, and a value indicative of the telemetry signal strength is obtained. Using a known correspondence between telemetry signal strength and recharge coupling efficiency for the IMD/recharging unit pair, the telemetry signal strength value is used to determine whether adequate recharge coupling may be achieved between the pair of devices. If so, a recharge session may be established. Otherwise, the antenna is repositioned and the process is repeated. The correspondence between telemetry signal strength and recharge coupling efficiency for the device pair may be developed empirically or using modeling.

Claims

1. For use in recharging an Implantable Medical Device (IMD) having a secondary recharge coil, a rechargeable power source, and an internal telemetry coil, a recharging system comprising:

an external telemetry coil to exchange a telemetry signal with the internal telemetry coil of the IMD;

a communication circuit coupled to receive, and to provide an indication of signal strength of, the exchanged telemetry signal; and

a control circuit coupled to receive the indication of signal strength, and to determine based on the indication of signal strength whether recharge coupling efficiency is adequate to initiate a recharge session between the recharging system and the IMD.

2. The system of claim 1, further comprising a primary recharge coil to inductively couple to the secondary recharge coil to establish the recharge session between the recharging system and the IMD.

3. The system of claim 2, further including a user interface device coupled to the control circuit to provide a user with an indication as to whether the primary recharge coil is to be repositioned.

4. The system of claim 3, wherein the user interface device is selected from a group consisting of an LED array, an audio transducer, a printer, a display screen, and a tactile feedback device.

5. The system of claim 1, further including a user interface device, and wherein the control circuit is configured to determine a recharge coupling efficiency value corresponding to the indication of signal strength, and to communicate at least one of the recharge coupling efficiency value and the indication of signal strength to a user via the user interface device.

6. The system of claim 1, wherein the communication circuit is configured to determine the indication of signal strength based on at least one of a downlink telemetry transmission received by the IMD and an uplink telemetry transmission transmitted by the IMD.

7. The system of claim 1, wherein the external telemetry coil is capable of exchanging with the internal telemetry coil of the IMD a telemetry signal that has been transmitted after the recharge session has been initiated.

8. The system of claim 7, wherein the control circuit is configured to provide an indication of whether recharge coupling efficiency of the recharge session that has been initiated is adequate.

9. The system of claim 1, further including a storage device coupled to the control circuit to store at least one signal strength map that associates each of one or more indications of signal strength with a respective recharge coupling efficiency value based on at least one of a group consisting of a type of the IMD, serial number of the IMD, a type of the recharging system, serial number of the recharging system, data describing a patient, therapy type being provided by the IMD, and a location of the IMD.

10. The system of claim 1, wherein the control circuit is adapted to determine that the recharge session may be initiated if the indication of signal strength has a predetermined relationship to a signal strength threshold value.

11. The system of claim 10, further including a storage device to store a signal strength map identifying at least one of the signal strength threshold value and the predetermined relationship, and wherein the control circuit determines whether to initiate the recharge session based on the signal strength map.

12. The system of claim 1, wherein the control circuit is adapted to automatically initiate the recharge session with the IMD if it is determined the recharge session may be initiated.

13. The system of claim 1, further including a storage device to store a signal strength map that provides a one-to-one correspondence between indications of signal strength and recharge coupling efficiency values.

14. The system of claim 13, wherein the control circuit is configured to perform at least one of

generating the signal strength map;

and

periodically updating the signal strength map.

15. A method for utilizing a recharging unit to recharge a rechargeable power source of an Implantable Medical Device (IMD), comprising:

transmitting at least one telemetry signal between the recharging unit and the IMD;

determining an indication of signal strength of the at least one telemetry signal; and

based on the indication of signal strength, determining whether adequate recharge coupling efficiency exists to initiate a recharge session.

16. The method of claim 15, further including using the indication of signal strength to determine a corresponding recharge coupling efficiency value of the recharge session that may be initiated.

17. The method of claim 16, further including providing at least one of the indication of signal strength and the recharge coupling efficiency value to the user.

18. The method of claim 15, further including providing an indication to a user that an antenna of the recharging unit must be repositioned relative to the IMD.

19. The method of claim 15, further including initiating the recharge session.

20. The method of claim 19, further including:

after the recharge session is initiated, transmitting at least one telemetry signal between the recharging unit and the IMD;

determining an indication of signal strength of the at least one telemetry signal that was transmitted after the recharge session was initiated; and

based thereupon,

providing an indication to a user as to whether an antenna of the recharging unit must be repositioned relative to the IMD.

21. The method of claim 15, further including determining whether the indication of signal strength has a predetermined relationship to a signal strength threshold value, and if so, indicating that the recharge session may be initiated.

22. The method of claim 21, further including retrieving at least one of the signal strength threshold value and the predetermined relationship from a signal strength map.

23. The method of claim 22, further including selecting the signal strength map that is to be used based on at least one of a group consisting of a type of the IMD, serial number of the IMD, a type of the recharging unit, serial number of the recharging unit, data describing a patient, a therapy type being provided by the IMD, and a location of the IMD.

24. The method of claim 15, further including automatically initiating the recharge session.

25. The method of claim 15, further including providing a signal strength map that provides associations between indications of recharge coupling efficiency and indications of signal strength for telemetry signals, and wherein the determination as to whether the recharge session may be initiated is based on the associations provided by the signal strength map.

26. The method of claim 25, further including generating an association to be included in the signal strength map, the association generated by:

positioning an antenna of the recharging unit at a location relative to the IMD;

transmitting a telemetry signal between the antenna and the IMD;

obtaining an indication of signal strength for the transmitted telemetry signal;

obtaining an indication of recharge coupling efficiency between the antenna and the IMD; and

generating an association between the obtained indication of signal strength and the obtained indication of recharge coupling efficiency.

27. The method of claim 25, wherein at least some of the associations are generated adaptively over time.

28. The method of claim 25, wherein at least some of the associations are generated while the signal strength map is being used to determine whether to initiate the recharge session.

29. The method of claim 25, wherein at least some of the associations are generated after the IMD is implanted in a body.

30. The method of claim 15, further comprising:

determining a threshold value for the recharge coupling efficiency;

identifying a signal strength threshold value based on the threshold value for the recharge coupling efficiency; and

comparing the signal strength threshold value to the indication of signal strength of the at least one telemetry signal to determine whether the recharge session may be initiated.

31. For use by a recharging unit that is adapted to recharge a power source of an Implantable Medical Devices (IMD), a digital storage device for storing programmed instructions to cause a control circuit of the recharging unit to perform a method, comprising:

transmitting a telemetry signal between the IMD and the recharging unit;

obtaining an indication of signal strength of the telemetry signal; and

determining, based the indication of signal strength, whether to initiate a recharge session between the recharging unit and the IMD.

32. The storage device of claim 31, wherein the method further comprises:

determining, from the indication of signal strength, a recharge coupling efficiency that may be achieved between the IMD and the recharging unit; and

determining based on at least one of the indication of signal strength and the recharge coupling efficiency whether to initiate the recharge session.

33. The storage device of claim 31, wherein the method further comprises using a signal strength map that associates indications of signal strength to recharge coupling efficiency to determine whether to initiate the recharge session.

34. The storage device of claim 33, wherein the method further comprises updating the signal strength map to include an association between the indication of signal strength for the telemetry signal and recharge coupling efficiency that would exist during a recharge session between the IMD and the recharging unit.

35. The storage device of claim 34, wherein updating the signal strength map occurs while positioning an antenna of the recharging unit prior to initiating the recharge session.

36. The storage device of claim 31, wherein the method further comprises performing one of initiating the recharge session and providing an indication to reposition an antenna of the recharging unit based on determining whether to initiate the recharge session.