Data logging system for implantable medical device

• US 6,628,985 B2
• Filed: 12/18/2000
• Issued: 09/30/2003
• Est. Priority Date: 12/18/2000
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sweeney, Robert J., Scheiner, Avram, Heil, Ronald W. Jr.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): DAHBOUR, HENRY
• Application Number:
  US09/740,258
• Publication Number:
  US 20020077563A1
• Time in Patent Office: 1,016 Days
• Field of Search: 600/510, 600/515, 600/518, 600/523, 600/524, 604/67, 607/3, 607/4, 607/5, 607/6, 607/7, 607/8, 607/9, 607/27, 607/28, 607/60, 607/30, 607/31, 607/32, 607/122, 607/123
• US Class Current: 600/510
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61N 1/30 Apparatus for iontophoresis, i.e. transfer of media in ionic state by an electromotoric force into the body, or cataphoresis
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate

Abstract

A data logging system and method in which an implantable medical device transmits logged data to an external data logging device with low energy potential signals. The implantable device generates potential signals modulated with digitally encoded data by operating a current source to cause corresponding electrical potentials that can be sensed at the skin surface by the external data logging device. The data logging device then demodulates the sensed potentials to derive the digital data and stores the data in a data logging storage medium.

Claims

1. A data logging system, comprising:

an implantable medical device having a current source for transmitting potential signals modulated with digitally encoded data to an external data logging device;

an external data logging device for affixation to a patient having incorporated therein a data communications interface for demodulating potential signals sensed at a skin surface location to extract digitally encoded data therefrom, and circuitry for storing the encoded data in a data logging storage medium; and

,

wherein the potential signals are transmitted in the form of a carrier waveform digitally modulated with the digitally encoded data by varying the amplitude of the carrier waveform.

2. The system of claim 1 wherein the potential signals are transmitted in the form of a digital pulse train modulated with the digitally encoded data by varying the frequency of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

3. The system of claim 1 wherein the potential signals are transmitted in the form of a digital pulse train modulated with the digitally encoded data by varying the width of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

4. The system of claim 1 wherein the potential signals are transmitted in the form of a digital pulse train modulated with the digitally encoded data by varying the position of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

5. The system of claim 1 wherein the implantable medical device is a cardiac device comprising a sensing channel for sensing electrical activity occurring in a patient'"'"'s heart and generating sensing signals in accordance therewith, the sensing signals then being used to make up a part of the data transmitted to the external data logging device.

6. The system of claim 1 wherein the data logging storage medium of the external data logging device is removable.

7. The system of claim 6 wherein the data logging storage medium is a flash ROM.

8. A method for data logging comprising:

generating potential signals modulated with digitally encoded logged data from an implantable medical device by operating a current source to cause corresponding electrical potentials that can be sensed at a skin surface location;

transmitting the potential signals in the form of a carrier waveform digitally modulated with the digitally encoded data by varying the amplitude of the carrier waveform;

receiving and demodulating sensed potential signals at a skin surface location to derive the logged data therefrom; and

,

storing the logged data in a data logging storage medium of an external data logging device.

9. The method of claim 8 further comprising removing and replacing the data logging storage medium at periodic intervals.

10. The method of claim 8 further comprising transmitting the potential signals in the form of a digital pulse train modulated with the digitally encoded data by varying the frequency of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

11. The method of claim 8 further comprising transmitting the potential signals in the form of a digital pulse train modulated with the digitally encoded data by varying the width of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

12. The method of claim 8 further comprising transmitting the potential signals in the form of a digital pulse train modulated with the digitally encoded data by varying the position of the pulses and amplitude modulating the carrier waveform with the modulated pulse train.

13. The method of claim 8 further comprising:

sensing electrical activity occurring in a patient'"'"'s heart and generating sensing signals in accordance therewith; and

using a part of the sensing signals to make up the logged data transmitted to the external data logging device.

14. The method of claim 8 further comprising performing an impedance measurement related to a physiological variable by injecting current between two electrodes from a constant current source and using the constant current source for transmitting potential signals modulated with digitally encoded data to the external data logging device.

15. A data logging system, comprising:

an implantable medical device having a current source for transmitting potential signals modulated with digitally encoded data to an external data logging device;

an external data logging device for affixation to a patient having incorporated therein a data communications interface for demodulating potential signals sensed at a skin surface location to extract digitally encoded data therefrom, and circuitry for storing the encoded data in a data logging storage medium; and

,

wherein the potential signals are transmitted in the form of a carrier waveform digitally modulated with the digitally encoded data by varying the frequency of the carrier waveform.

16. A data logging system, comprising:

an implantable medical device having a current source for transmitting potential signals modulated with digitally encoded data to an external data logging device;

an external data logging device for affixation to a patient having incorporated therein a data communications interface for demodulating potential signals sensed at a skin surface location to extract digitally encoded data therefrom, and circuitry for storing the encoded data in a data logging storage medium; and

,

wherein the implantable medical device comprises circuitry for performing an impedance measurement related to a physiological variable by injecting current between two electrodes from a constant current source and further wherein the constant current source is used for transmitting potential signals modulated with digitally encoded data to the external data logging device.

17. A method for data logging comprising:

generating potential signals modulated with digitally encoded logged data from an implantable medical device by operating a current source to cause corresponding electrical potentials that can be sensed at a skin surface location;

transmitting the potential signals in the form of a carrier waveform digitally modulated with the digitally encoded data by varying the frequency of the carrier waveform;

receiving and demodulating sensed potential signals at a skin surface location to derive the logged data therefrom; and

,

storing the logged data in a data logging storage medium of an external data logging device.

18. A method for data logging comprising:

generating potential signals modulated with digitally encoded logged data from an implantable medical device by operating a current source to cause corresponding electrical potentials that can be sensed at a skin surface location;

receiving and demodulating sensed potential signals at a skin surface location to derive the logged data therefrom;

storing the logged data in a data logging storage medium of an external data logging device; and

,

performing an impedance measurement related to a physiological variable by injecting current between two electrodes from a constant current source and using the constant current source for transmitting potential signals modulated with digitally encoded data to the external data logging device.

19. The method of claim 18 further comprising:

sensing electrical activity occurring in a patient'"'"'s heart and generating sensing signals in accordance therewith; and

using a part of the sensing signals to make up the logged data transmitted to the external data logging device.