Time domain reflectometer-integrity testing system and method for implantable electrode

• US 5,231,987 A
• Filed: 04/10/1992
• Issued: 08/03/1993
• Est. Priority Date: 04/10/1992
• Status: Expired due to Fees

• Current Assignee: Random Technologies LLC
• Original Assignee: Random Technologies LLC
• Inventors: Robson, Jack R.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US07/866,850
• Time in Patent Office: 480 Days
• Field of Search: 128/419, 128/419 PG
• US Class Current: 607/29
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371

Abstract

A device, system and method is used for testing the integrity of an implantable electrode. The electrical device has a receptacle for an electrode and includes a time domain reflectometer comprising an output signal mechanism operatively connected to the electrode receptacle. The method of analyzing the integrity of an implanted electrode comprises the steps of generating a time domain reflectometer (TDR) reading (output signal) from the electrode, and transmitting the signal to an output device. The output signal may be analyzed to determined whether it varies by a predetermined threshold, or it may be compared to a previously generated signal from the electrode so that differences in the electrical characteristics of the electrode may be identified. The present device, system and method allows a cardiologist or technician to ensure that the electrode is properly implanted and to non-invasively determine the integrity of the electrode over a patient'"'"'s life.

Claims

1. An electrical device implantable in a body, the device comprising means for receiving a first electrode, comprising:

time domain reflectometer means operatively connected to the means for receiving the electrode, the time domain reflectometer means comprising output signal means.

2. The device of claim 1 wherein the device comprises a pacemaker.

3. The device of claim 1 wherein the device comprises an automatic implantable cardioverter defibrillator.

4. The device of claim 1 wherein the output signal of the means comprises a single TDR reading from the time domain reflectometer.

5. The device of claim 1 wherein the output signal of the device comprises a composite reading from multiple readings from the time domain reflectometer.

6. The device of claim 5, wherein the composite reading from multiple readings comprises an average of the multiple readings based upon a user-designated number of TDR readings from the time domain reflectometer.

7. The device of claim 1 further comprising:

means for storing multiple output signal means.

8. The device of claim 7 further comprising:

means for associating each stored output signal with a time reference indicating when the output signal is generated.

9. The device of claim 7 further comprising:

means for transmitting a specified stored output signal through the output signal means.

10. The device of claim 1 wherein the time domain reflectometer means comprises means for transmitting an electrical signal to the electrode receiving means, and

wherein the device further comprises

an anti-coincidence detector adapted to prevent a signal generated by the transmitting means from interfering with the signal generated by the time domain reflectometer.

11. The device of claim 1 further comprising:

means for actuating the time domain reflectometer to generate an output signal, the actuating means comprising an electromagnetic wave receiver.

12. The device of claim 1 further comprising:

means for transmitting an output signal generated by the time domain reflectometer, the transmitting means comprising an electromagnetic wave transmitter.

13. The device of claim 1, wherein the time domain reflectometer further comprises:

a pulse generator, and

an array of selectable source resistors through which a pulse generated by the pulse generator may be transmitted.

14. The device of claim 1, wherein the device further comprises:

means for receiving a TDR blanking interval signal to the time domain reflectometer, and

means for deferring generation of a TDR pulse until the amount of time specified by the TDR blanking interval has elapsed after the transmission of a stimulating pulse, or occurance of an identified physiological event, on the electrode.

15. The device of claim 1, wherein the device further comprises:

means for receiving a TDR base time signal to the time domain reflectometer, and

means for deferring storing of the reflected TDR incident pulse until the amount time specified by the TDR base time signal has elapsed after the generation of a TDR pulse.

16. The device of claim 1, wherein the device further comprises:

means for connecting the device to a second implantable electrode, and

switch means for selecting whether the time domain reflectometer is operably connected to the means for connecting the first implantable electrode or the means for connecting to the second implantable electrode.

17. The device of claim 1, wherein the device further comprises:

means for storing information regarding an electrode connectable to the device, and

means for transmitting the stored information through the output signal means.

18. A system for displaying a time domain reflectometer output signal, comprising:

a device of claim 10, and

a graphical display means operatively connected to a receiving means for receiving a transmitted output signal from the device of claim 8.

19. A method of analyzing the integrity of an electrode implanted in a body comprising the steps of:

generating a first time domain reflectometer (TDR) reading from the implanted electrode, and

transmitting the generated TDR reading to an output means.

20. The method of claim 19, further comprising the step of:

providing a reference time domain reflectometer reading, and

comparing the first and reference time domain reflectometer readings and

generating an indicating output based on whether the first and reference output signals vary by a predefined threshold.

21. The method of claim 19 wherein the implanted electrode comprises a pacemaker electrode.

22. The method of claim 19 wherein the implanted electrode comprises an automatic implantable cardioverter defibrillator electrode.

23. The method of claim 19 further comprising the step of

generating multiple output signals from the time domain reflectometer, and

combining the multiple output signals to form a composite output signal.

24. The method of claim 23, wherein the composite reading from multiple readings comprises an average of the multiple readings based upon a user-designated number of TDR readings from the time domain reflectometer.

25. The method of claim 19, further comprising the step of:

selecting a source resistance for the incident pulse generated by the time domain reflectometer.

26. The method of claim 19, further comprising the step of:

storing the generated TDR reading.

27. The method of claim 26, further comprising the step of:

associating each stored output signal with a time reference indicating when the TDR reading is generated.

28. The method of claim 19, further comprising the step of:

transmitting a previously stored output signal through the output means.

29. The method of claim 19, wherein the output means comprises an electromagnetic wave receiver.

30. The method of claim 19, further comprising the steps of:

providing a TDR blanking interval signal, and

deferring generation of a TDR pulse until the amount of time specified by the TDR blanking interval has elapsed after the transmission of a stimulating pulse, or the occurrence of an identified physiological event, on the electrode.

31. The method of claim 19, further comprising the steps of:

providing a TDR base time signal to the time domain reflectometer, and

deferring the storing of the reflected TDR incident pulse until the amount time specified by the TDR base time signal has elapsed after the generation of a TDR pulse.

32. The method of claim 19, further comprising the steps of:

graphically displaying the generated TDR reading.

33. The method of claim 32 further comprising the steps of:

providing a reference output signal, and

superimposing the reference output signal on the graphically displayed generated output signal.

34. The method of claim 32 further wherein the generated output signal is displayed on a screen monitor.

35. The method of claim 32 further wherein the generated output signal is displayed on a printer.

36. The method of claim 19, further comprising the steps of:

selecting a portion of the generated TDR reading, and

graphically displaying the selected portion of the TDR reading.

37. A system for testing the integrity of an implanted electrode, the implanted electrode being connected to device comprising a transceiver means and a time domain reflectometer connected to the electrode, the time domain reflectometer being capable of generating an output signal, comprising:

means for transmitting a signal to the device transceiver means commanding the time domain reflectometer to generate a first TDR reading from the implanted electrode and transmit TDR reading through the transceiver, and

means for receiving the transmitted first TDR reading.

38. The system of claim 37, wherein the system further comprises:

means for storing multiple received TDR readings,

means for comparing at least two of the transmitted TDR readings, and

means for indicating whether the compared TDR readings vary by a predefined threshold.

39. The system of claim 37, wherein the system further comprises:

means for graphically displaying the received first TDR reading.

40. The system of claim 39, wherein the system further comprises:

means for selecting a portion of the first TDR reading to be graphically displayed.

41. The system of claim 39, wherein:

the first TDR reading is graphically displayed using an axis indicating the time/distance of the output signal, and

wherein the system further comprises means for selecting the time/distance scale at which the first TDR reading is graphically displayed.

42. The system of claim 39, wherein the system further comprises means for superimposing a distance scale measurement corresponding to the length of the implanted electrode on the graphical display.

43. The system of claim 37, wherein the system further comprises:

means for storing a second TDR reading and graphically displaying it superimposed over the first TDR reading.

44. The system of claim 37, wherein the system further comprises:

means for storing a second TDR reading,

means for comparing the first and second TDR readings, and

means for indicating whether the compared TDR readings vary by a predefined threshold.

45. The system of claim 37, wherein the system further comprises:

means for adjusting the a vertical reference point for the graphical display.

46. The system of claim 37, wherein the system further comprises means for adjusting the vertical sensitivity of the graphical display.

47. The system of claim 37, wherein the graphical display means comprises a screen monitor.

48. The system of claim 37, wherein the graphical display means comprises a printer.

49. The system of claim 37, wherein the device comprises means for generating the first TDR reading by forming a composite reading from multiple TDR readings.

50. The system of claim 49 wherein the system further comprises:

means for transmitting a signal to the device transceiver means indicating the number of TDR readings to use to form the composite signal.

51. The system of claim 37, wherein the system further comprises:

means for storing multiple received TDR readings,

means for generating a TDR reading comprising a composite of individual TDR readings.

52. The device of claim 51, wherein the composite TDR reading comprises an average of the multiple readings based upon a user designated number of readings from the time domain reflectometer.

53. The system of claim 37, wherein the time domain reflectometer further comprises an incident pulse generator, and wherein the system further comprises:

means for selecting a value indicating the source resistance of an incident pulse to be generated by the time domain reflectometer, and

means for transmitting the selected value to the device.

54. The system of claim 37, wherein the system further comprises:

means for specifying a propagation velocity factor for the first TDR reading.

55. The system of claim 37, wherein the system further comprises:

means for selecting a set of properties for the implanted electrode from a database of electrode properties, and

means for displaying at least one of the selected properties.

56. The system of claim 37, wherein the system further comprises:

means for specifying a TDR blanking interval for a TDR reading to be made by the time domain reflectometer of the implanted device, and

means for transmitting the specified TDR blanking interval to the transceiver means.

57. The system of claim 37, wherein the system further comprises:

means for specifying a TDR base time for a TDR reading to be made by the time domain reflectometer, and

means for transmitting the specified TDR base time to the transceiver means.

58. The system of claim 37, wherein the transceiver means comprises and RF transceiver.

59. The system of claim 37, wherein the transceiver means comprises a serial data port.

60. The system of claim 37, wherein the device comprises data storage means and the system further comprises:

means for transmitting an instruction to the device commanding the device to store a TDR reading.

61. The system of claim 37, wherein the device comprises data storage means and the system further comprises:

means for transmitting an instruction to the device commanding the device transmit to the system a previously stored TDR reading.

62. The system of claim 37, wherein the system further comprises:

means for displaying the amplitude differential between the incident pulse and a selected portion of the first TDR reading.

63. The system of claim 37, wherein the device is connected to a plurality of implanted electrodes and includes switch means for selecting which of the implantable electrodes the time domain reflectometer is connected to, further comprising:

means for commanding the device for operably connect the time domain reflectometer to a designated implanted electrode.

64. The system of claim 37, further comprising:

means for commanding the device for operably connected to the time domain reflectometer to transmit stored information regarding an electrode connected to the device to the system.