System And Method For In Situ Trimming Of Oscillators In A Pair Of Implantable Medical Devices

• US 20090177251A1
• Filed: 01/07/2009
• Published: 07/09/2009
• Est. Priority Date: 01/07/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Tran, Binh C., Harris, Thomas J., Huelskamp, Paul, Vijayagopal, Ramprasad
• Granted Patent: US 8,041,431 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient

Abstract

A system and method for in situ trimming of oscillators in a pair of implantable medical devices is provided. Each frequency over a range of oscillator trim frequencies for an initiating implantable medical device is selected and a plurality of commands are sent via an acoustic transducer in situ over the frequency selected. Each frequency over a range of oscillator trim frequencies for a responding implantable medical device is selected and a response to each of the commands received is sent via an acoustic transducer in situ over the frequency selected. The responses received by the initiating implantable medical device are evaluated and a combination of the oscillator trim frequencies for both implantable medical devices that together exhibit a strongest acoustic wave is identified. Oscillators in both implantable medical devices are trimmed to the oscillator trim frequencies in the combination identified.

Claims

1. A system for in situ trimming of oscillators in a pair of implantable medical devices, comprising:

an initiating implantable medical device, comprising;

control circuitry configured to select each frequency over a range of oscillator trim frequencies; and

an acoustic transducer configured to send a plurality of commands in situ over the frequency selected;

a responding implantable medical device, comprising;

control circuitry configured to select each frequency over a range of oscillator trim frequencies; and

an acoustic transducer configured to send a response to each of the commands received in situ over the frequency selected,

wherein control circuitry comprised in the initiating implantable medical device is further configured to evaluate the responses received by the initiating implantable medical device and to identify a combination of the oscillator trim frequencies for both implantable medical devices that together exhibit a strongest acoustic wave; and

both implantable medical devices are configured to trim oscillators to the oscillator trim frequencies in the combination identified.

2. A system according to claim 1, further comprising:

on the responding implantable medical device, non-volatile memory in which a reference oscillator trim frequency is maintained and volatile memory in which the oscillator trim frequency identified is stored,

wherein the control circuitry of the responding implantable medical device is further configured to automatically recover the reference oscillator trim frequency through erasure of the volatile memory.

3. A system according to claim 2, wherein the control circuitry of the responding implantable medical device is further configured to replace the reference oscillator frequency maintained in the non-volatile memory with the oscillator frequency stored in the volatile memory.

4. A system according to claim 1, wherein the acoustic transducer of the initiating implantable medical device is further configured to send a start command and an end command in situ, and the control circuitry of the responding implantable medical device is further configured commence a clock pulse count upon receipt of the start command, to stop the clock pulse count upon receipt of the end command, and to provide the clock pulse count to the initiating implantable medical device via the acoustic transducer in situ, further comprising:

evaluation circuitry configured to establish an actual oscillator frequency in use by the responding implantable medical device by evaluating the clock pulse count, and to provide the actual oscillatory frequency to the responding implantable medical device.

5. A system according to claim 1, further comprising:

a memory configured to logically map the ranges of the oscillator trim frequencies for both responding implantable medical devices into a search space, wherein the frequencies selected are picked by both of the implantable medical devices by heuristically sweeping over the search space in a search pattern comprising one of an exhaustive, a selective, and a progressively-defined grid.

6. A method for in situ trimming of oscillators in a pair of implantable medical devices, comprising:

selecting each frequency over a range of oscillator trim frequencies for an initiating implantable medical device and sending a plurality of commands via an acoustic transducer in situ over the frequency selected;

selecting each frequency over a range of oscillator trim frequencies for a responding implantable medical device and sending a response to each of the commands received via an acoustic transducer in situ over the frequency selected;

evaluating the responses received by the initiating implantable medical device and identifying a combination of the oscillator trim frequencies for both implantable medical devices that together exhibit a strongest acoustic wave; and

trimming oscillators in both implantable medical devices to the oscillator trim frequencies in the combination identified.

7. A method according to claim 6, further comprising:

on the responding implantable medical device, maintaining a reference oscillator trim frequency in non-volatile memory and storing the oscillator trim frequency identified in volatile memory; and

automatically recovering the reference oscillator trim frequency for the responding implantable medical device through erasure of the volatile memory.

8. A method according to claim 7, further comprising:

replacing the reference oscillator frequency maintained in the non-volatile memory with the oscillator frequency stored in the volatile memory.

9. A method according to claim 6, further comprising:

sending a start command from the initiating implantable medical device via the acoustic transducer in situ;

commencing a clock pulse count on the responding implantable medical device upon receipt of the start command;

sending an end command from the initiating implantable medical device via the acoustic transducer in situ;

stopping the clock pulse count on the responding implantable medical device upon receipt of the end command and providing the clock pulse count to the initiating implantable medical device via the acoustic transducer in situ;

establishing an actual oscillator frequency in use by the responding implantable medical device by evaluating the clock pulse count; and

providing the actual oscillatory frequency to the responding implantable medical device.

10. A method according to claim 6, further comprising:

logically mapping the ranges of the oscillator trim frequencies for both responding implantable medical devices into a search space;

picking the frequencies selected by heuristically sweeping over the search space in a search pattern comprising one of an exhaustive, a selective, and a progressively-defined grid.

11. A system for intracorporeal trimming of acoustic transducers for a plurality of interconnected implantable medical devices, comprising:

a two-dimensional search space comprising a range of oscillator trim frequencies for an initiating and a responding implantable medical device;

an initiating implantable medical device configured to perform a sweep of the oscillator trim frequency ranges, comprising;

a frequency selector configured to select each oscillator trim frequency in the search space;

a testing module configured to send a series of commands to the responding implantable medical device at the selected oscillator trim frequency via an acoustic transducer;

a responding implantable medical device configured to perform a sweep of the oscillator trim frequency ranges, comprising;

a frequency selector configured to select each oscillator trim frequency in the search space;

a response module configured to send a response to each command that is received to the initiating implantable medical device at the selected oscillator trim frequency via an acoustic transducer;

an evaluation module on the initiating implantable medical device configured to evaluate the responses received by the initiating implantable medical device from the responding implantable medical device and to select the oscillator trim frequencies indicating a strongest acoustic wave, wherein the oscillators on both implantable medical devices are set to the selected oscillator trim frequencies.

12. A system according to claim 11, wherein the oscillator trim frequency ranges are exhaustively defined over a complete set of the oscillator frequencies for both the initiating and the responding implantable medical device.

13. A system according to claim 11, wherein the oscillator trim frequency ranges are selectively defined over a subset of the oscillator frequencies for both the initiating and the responding implantable medical device by applying a selection criteria.

14. A system according to claim 13, further comprising:

a reference pairing of oscillator trim frequencies designated within the search space, wherein a pattern is mapped at a radius r specified as a continuous monotonic function of an angle θ

measured from the reference pairing, and those oscillator trim frequencies falling within a fixed distance of the pattern are selected.

15. A system according to claim 11, wherein the oscillator trim frequency ranges are progressively defined over a complete set of the oscillator frequencies for both the initiating and the responding implantable medical device by only adding the oscillator trim frequencies adjacent to a currently selected oscillator trim frequency, which yields an improvement in acoustic wave strength.

16. A system according to claim 11, further comprising:

a volatile memory configured to save the selected oscillator trim frequency for the responding implantable medical device; and

a non-volatile memory configured to recover a previous oscillator trim frequency upon loss of communications or error.

17. A system according to claim 11, further comprising:

a synchronization module on the initiating implantable medical device configured to send a timed pair of commands to the responding implantable medical device;

a counter on the responding implantable medical device configured to count clock pulses between receipt of the commands,

wherein the synchronization module is further configured to compare the clock pulses counted to an expected number of clock pulses to establish the actual oscillator trim frequency of the responding implantable medical device.

18. A method for intracorporeal trimming of acoustic transducers for a plurality of interconnected implantable medical devices, comprising:

mapping a two-dimensional search space comprising a range of oscillator trim frequencies for an initiating and a responding implantable medical device;

on the initiating implantable medical device, performing a sweep of the oscillator trim frequency ranges, comprising;

selecting each oscillator trim frequency in the search space;

sending a series of commands to the responding implantable medical device at the selected oscillator trim frequency via an acoustic transducer;

on the responding implantable medical device, performing a sweep of the oscillator trim frequency ranges, comprising;

selecting each oscillator trim frequency in the search space;

sending a response to each command that is received to the initiating implantable medical device at the selected oscillator trim frequency via an acoustic transducer;

evaluating the responses received by the initiating implantable medical device from the responding implantable medical device and selecting the oscillator trim frequencies indicating a strongest acoustic wave; and

setting the oscillators on both implantable medical devices to the selected oscillator trim frequencies.

19. A method according to claim 18, further comprising:

exhaustively defining the oscillator trim frequency ranges over a complete set of the oscillator frequencies for both the initiating and the responding implantable medical device.

20. A method according to claim 18, further comprising:

selectively defining the oscillator trim frequency ranges over a subset of the oscillator frequencies for both the initiating and the responding implantable medical device by applying a selection criteria.

21. A method according to claim 20, further comprising:

designating a reference pairing of oscillator trim frequencies within the search space;

mapping a pattern at a radius r specified as a continuous monotonic function of an angle θ

measured from the reference pairing; and

selecting those oscillator trim frequencies falling within a fixed distance of the pattern.

22. A method according to claim 18, further comprising:

progressively defining the oscillator trim frequency ranges over a complete set of the oscillator frequencies for both the initiating and the responding implantable medical device by only adding the oscillator trim frequencies adjacent to a currently selected oscillator trim frequency, which yields an improvement in acoustic wave strength.

23. A method according to claim 18, further comprising:

saving the selected oscillator trim frequency for the responding implantable medical device in volatile memory; and

recovering a previous oscillator trim frequency from non-volatile memory upon loss of communications or error.

24. A method according to claim 18, further comprising:

on the initiating implantable medical device, sending a timed pair of commands to the responding implantable medical device;

on the responding implantable medical device, counting clock pulses between receipt of the commands; and

compare the clock pulses counted to an expected number of clock pulses to establish the actual oscillator trim frequency of the responding implantable medical device.