System and method for RF wake-up of implantable medical device

• US 8,326,424 B2
• Filed: 08/26/2011
• Issued: 12/04/2012
• Est. Priority Date: 04/07/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Bange, Joseph E., Koshiol, Allan T., Kramer, Karen M., Holmquist, Paul, Harris, Thomas J.
• Primary Examiner(s): Layno, Carl H.
• Assistant Examiner(s): MORALES, JON ERIC C
• Application Number:
  US13/218,672
• Publication Number:
  US 20110313491A1
• Time in Patent Office: 466 Days
• Field of Search: 607/32, 607/60
• US Class Current: 607/32
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/37276 characterised by means for reducing power consumption during telemetry

Abstract

A telemetry system is presented for enabling radio-frequency (RF) communications between an implantable medical device and an external device in a manner which reduces the power requirements of the implantable device by duty cycling its circuitry. A wakeup scheme for the implantable device is provided in which the external device transmits a data segment containing a repeating sequence of special wakeup characters in order to establish a communications session with the implantable device. The wakeup scheme may be designed to operate in the context of a handshaking protocol for collision avoidance.

Claims

1. A telemetry system for enabling radio-frequency (RF) communications between an implantable medical device and an external remote monitor (RM), comprising:

an antenna, an RF transmitter, an RF receiver, and a controller incorporated into each of the implantable device and the RM;

a wakeup timer incorporated into the implantable device;

wherein the RF transmitter and RF receiver of the implantable device are interfaced to the controller to enable the RF transmitter and RF receiver to be powered up or down;

wherein the RM is programmed to transmit a data segment containing a repeating sequence of special wakeup characters in order to establish an RF communications session with the implantable device;

wherein the implantable device is programmed to;

power up its RF receiver for a specified time window at periodic intervals to wait for receipt of a special wakeup character transmitted by the RM;

maintain its RF receiver and place its RF transmitter in a powered-up state upon receipt of the special character and for as long as consecutive special wakeup characters continue to be received; and

transmit an acknowledge signal upon receipt of at least one character other than a special wakeup character; and

wherein the RM is programmed to;

establish a communications session with the implantable device when a response to the acknowledge signal is received by the implantable device; and

adjust a periodic interval at which the RM transmits the special wakeup characters to the implantable device according to when previous successful communications sessions have been established.

2. The system of claim 1, wherein the RM is programmed to adjust the periodic intervals at which the RM transmits the special wakeup characters according to a time of day at which past successful communications sessions were established.

3. The system of claim 1, wherein the RM is programmed to adjust the periodic interval at which the RM transmits the special wakeup characters according to previous communication sessions in which data was collected from the implantable device by the RM.

4. The system of claim 1, wherein the RM is programmed to perform a discovery process to contend for message traffic upon receiving the acknowledge signal.

5. The system of claim 4, wherein the RM is programmed to monitor monitoring signal strength and perform the discovery process if there is found to be some activity.

6. The system of claim 1, wherein the RM is programmed to transmit a request-to-send message and a clear-to-send message from the RM prior to transmitting the data segment.

7. The system of claim 1, wherein the specified time window is longer than a time required for both stabilization of the receiver and sending of two special wakeup characters of the plurality of special wakeup characters.

8. The system of claim 1, wherein the RM includes a user interface and wherein the RM is programmed to transmit, in addition to the periodic interval, the plurality of special wakeup characters to the implantable device to establish a communications session when a user command is received via the user interface.

9. The system of claim 1, wherein the RM is programmed to transmit the plurality of special characters daily to establish the communication session.

10. The system of claim 1, wherein the implantable device is programmed to maintain its receiver and transmitter in the powered-up state for an extended time period after transmitting the acknowledge signal.

11. A method by which an external remote monitoring device (RM) communicates with an implantable medical device via a wireless telemetry system, comprising:

transmitting a data segment containing a repeating sequence of special wakeup characters from the RM in order to establish an communications session with the implantable device;

powering up an receiver of the implantable device for a specified time window at periodic intervals to wait for receipt of a special wakeup character transmitted by the RM, wherein the implantable device maintains the receiver and an transmitter in a powered-up state upon receipt of a special character and for as long as consecutive special wakeup characters continue to be received;

transmitting, by the implantable device, an acknowledge signal upon receipt of at least one character other than a special wakeup character;

establishing a communications session with the implantable device when a response to the acknowledge signal is received by the implantable device; and

adjusting, by the RM, a periodic interval at which the RM transmits the special wakeup characters to the implantable device according to when previous successful communications sessions have been established.

12. The method of claim 11, wherein adjusting a periodic interval at which the RM transmits the special wakeup characters includes adjusting the periodic intervals to a time of day at which past successful communications sessions were established.

13. The method of claim 11, wherein adjusting a periodic interval at which the RM transmits the special wakeup characters includes adjusting the periodic intervals according to previous communication sessions in which data was collected from the implantable device by the RM.

14. The method of claim 11, wherein establishing a communications session includes the RM, upon receiving the acknowledge signal, performing a discovery process to contend for message traffic.

15. The method of claim 14, including monitoring signal strength with the RM, and wherein performing the discovery process includes performing the discovery process if there is found to be some activity.

16. The method of claim 11, wherein transmitting the data segment includes transmitting a request-to-send message and a clear-to-send message from the RM prior to transmitting the data segment.

17. The method of claim 11, wherein powering up the receiver of the implantable device includes powering up the receiver for a specified time window that is longer than a time required for both stabilization of the receiver and sending of two special wakeup characters of the plurality special wakeup characters.

18. The method of claim 11, including transmitting, in addition to the periodic interval, the plurality of special wakeup characters to the implantable device to establish a communications session when a user command is received into the RM via a user interface of the RM.

19. The method of claim 11, wherein transmitting the plurality of special characters includes transmitting the plurality of special characters daily to establish the communication session.

20. The method of claim 11, including maintaining the receiver and the transmitter of the implantable device in the powered-up state for an extended time period after transmission of the acknowledge signal.