Implanted medical device/external medical instrument communication utilizing surface electrodes

• US 20040172104A1
• Filed: 01/22/2004
• Published: 09/02/2004
• Est. Priority Date: 10/29/1999
• Status: Active Application

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Nelson, Chester G., Emst, Jill H., Wilkinson, Jeffrey D., Berg, Gary, Stomberg, Charles
• Application Number:
  US10/763,989
• Publication Number:
  US 20040172104A1
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique

Abstract

A medical device communications system uses subthreshold pulses, modulated to provide relatively high speed electrical communications with inexpensive external devices connectable to a body with the implant by surface leads.

Claims

1. A communications system for use with an implantable medical device, comprising:

a pulse generation circuit to deliver a first electrical signal at a first threshold to electrically stimulate body tissue;

a control circuit coupled to the pulse generation circuit, the control circuit to cause the pulse generation circuit to deliver a second signal at a second threshold below the first threshold to prevent substantial physiological effects in response to the second signal, the second signal including encoded data; and

a receiving circuit to receive the second signal, enabling external transfer of the encoded data.

2. The system of claim 1, wherein the second signal is a modulated biphasic pulse.

3. The system of claim 2, wherein the biphasic pulses are delivered during a refractory period.

4. The system of claim 2, wherein the second signal is an amplitude modulated biphasic pulse.

5. The system of claim 2, wherein the second signal is a frequency modulated biphasic pulse.

6. The system of claim 2, wherein the second signal is a pulse-width modulated biphasic pulse.

7. The system of claim 6, wherein the pulse generation circuit includes a circuit to perform pulse train modulation on the second signal.

8. The system of claim 6, wherein the pulse generation circuit includes a circuit to control the polarity of the biphasic pulse.

9. The system of claim 1, further comprising a trigger circuit coupled to the control circuit to receive a trigger signal from outside the body, the control circuit causing the pulse generation circuit to deliver the second signal in response to the trigger signal.

10. A method of providing communication between an implantable medical device and an external device, comprising the steps of:

generating a first electrical signal at a first threshold to electrically stimulate body tissue;

generating a second electrical signal, including encoded data, at a second threshold below the first threshold to prevent physiological effects in response to the second signal; and

sensing the generation of second signal at the external device.

11. The method of claim 10, wherein the second signal corresponds to multiple biphasic pulses.

12. The method of claim 11, wherein the second signal corresponds to modulated biphasic pulses.

13. The method of claim 11, wherein the second signal is delivered at a predetermined time relative to a cardiac cycle of the heart.

14. The method of claim 10, further comprising the step of providing an external signal from outside the body to trigger delivery of the second signal.

15. The method of claim 10, wherein the second signal includes marker channel data.

16. The method of claim 10, wherein the second signal corresponds to patient data.

17. The method of claim 10, wherein the second signal corresponds to device-specific data.

18. The communications system of claim 10, wherein the second electrical pulses are transmitted during segments of time related to one of a sensed cardiac event and a pacing pulse.

19. The system of claim 10, wherein the second signal is transmitted during segments of time related to one of a sensed cardiac event and a pacing pulse.

20. The method of claim 10, wherein the second electrical signal is generated during segments of time related to one of a sensed cardiac event and a pacing pulse.