Device for detecting tachycardiac rhythm disturbances

• US 6,961,614 B2
• Filed: 02/19/2001
• Issued: 11/01/2005
• Est. Priority Date: 02/17/2000
• Status: Expired due to Fees

• Current Assignee: Biotronik SE & Company KG
• Original Assignee: Gerry C. Kaye
• Inventors: Kaye, Gerry C.
• Primary Examiner(s): Manuel, George
• Assistant Examiner(s): Faulcon, Jr., Lenwood
• Application Number:
  US10/203,976
• Publication Number:
  US 20030105494A1
• Time in Patent Office: 1,716 Days
• Field of Search: 607/14, 607/17, 607/20, 607/24, 600/547
• US Class Current: 607/14
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

A device for detecting tachycardiac rhythm disturbances, has a measuring unit for picking up and reproducing a measurement signal dependent on intracardial impedance at its output and an evaluation unit connected at the input to the measuring unit. The evaluation unit is adapted to output both a first signal which corresponds to the difference of a maximum and a minimum measurement signal within at least one predeterminable period of time and also a second signal which is dependent on the integral of the measurement signal over at least one predeterminable period of time.

Claims

1. A device for detecting tachycardiac rhythm disturbances, comprising:

a measuring unit for picking up and reproducing a measurement signal dependent on intracardial impedance at an output thereof; and

an evaluation unit for detecting tachycardiac rhythm disturbances which is connected at an input side thereof to the measuring unit and which is adapted to determine an output a first signal which corresponds to the difference of a maximum and a minimum measurement signal within at least one defined period of time,

wherein the evaluation unit is additionally adapted to determine and output a second signal which is dependent on the integral of the measurement signal over at least one defined second period of time, and the first signal associated with the second period of time, wherein the first-mentioned period of time is before the second period of time or is identical to the second period of time.

2. The device of claim 1, further comprising:

means for measuring unipolar impedance.

3. The device of claim 1, further comprising:

means for measuring bipolar impedance.

4. The device of claim 1, wherein the measuring unit comprises at least two electrodes, of which at least one can be introduced into a chamber of the heart.

5. The device of claim 4, further comprising:

a current source connected to the electrodes in such a way that it produces a predetermined measuring current between the electrodes; and

voltage measuring means connected to the electrodes for measuring an electrical voltage therebetween.

6. The device of claim 4, further comprising:

a voltage source connected to the electrodes in such a way that it produces a predetermined measuring voltage between the electrodes, and

current measuring means connected to the electrodes for measuring an electrical current therebetween.

7. The device of claim 5, wherein the current source is adapted to output an alternating current with a predetermined time dependency.

8. The device of claim 7, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the voltage measuring means, which is modulated by the alternating current produced by the current source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

9. The device of claim 1, further comprising:

a filter stage for the removal of measurement signal components of a frequency of up to a maximum of 1 Hz.

10. The device of claim 1, further comprising:

control means adapted to cause the evaluation unit to start or stop integration of a signal at the input of the evaluation unit.

11. The device of claim 10, wherein the control means is so designed to cause the evaluation unit to effect integration respectively over the period of time of one or some cardiac periods.

12. The device of claim 10, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

13. The device of claim 10, wherein the evaluation unit has a memory.

14. The device of claim 13, wherein the evaluation unit is so designed that within the predetermined period of time the hitherto maximum and minimum signals at the input of the evaluation unit are continuously determined and stored in the memory, that at the end of the period of time the difference between the currently stored maximum and minimum signals is calculated and that at the beginning of a respective subsequent period of time the signals last stored in the preceding period of time are erased from the memory.

15. The device of claim 14, wherein the control means is connected to the evaluation unit and designed to signal to the evaluation unit the beginning and the end of the predetermined period of time.

16. The device of claim 15, wherein the control means is designed to cause the evaluation unit to effect integration and to determine the difference between the maximum and the minimum respectively within the same period of time.

17. The device of claim 16, wherein the evaluation unit is so designed that in operation of the device at the end of the respective period of time the evaluation unit outputs a signal which corresponds to the integral of the measurement signal over the period of time less the product of the duration of the period of time and the measurement signal minimum of the period of time.

18. The device of claim 17, further comprising:

a respective comparator connected to a reference value memory containing reference values and/or reference value ranges and which is so designed that in operation of the device the comparator compares the difference of the extreme values or the time integral of the measurement signal to a respective reference value or reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the reference value or reference value range or not and possibly what deviation is involved.

19. The device of claim 17, further comprising:

a respective comparator connected to a reference value memory containing fluctuation reference values and/or fluctuation reference value ranges and which is so designed that in operation of the device the comparator compares the change in the difference of the extreme values or the time integral of the measurement signal in relation to the respectively precedingly determined value to a respective fluctuation reference value or fluctuation reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the fluctuation reference value or fluctuation reference value range or not and possibly what deviation is involved.

25. The device of claim 2, wherein the measuring unit comprises at least two electrodes, of which at least one can be introduced into a chamber of the heart.

26. The device of claim 3, wherein the measuring unit comprises at least two electrodes, of which at least one can be introduced into a chamber of the heart.

27. The device of claim 25, further comprising:

a current source connected to the electrodes in such a way that it produces a predetermined measuring current between the electrodes; and

voltage measuring means connected to the electrodes for measuring an electrical voltage therebetween.

28. The device of claim 26, further comprising:

a current source connected to the electrodes in such a way that it produces a predetermined measuring current between the electrodes; and

voltage measuring means connected to the electrodes for measuring an electrical voltage therebetween.

29. The device of claim 25, further comprising:

a voltage source connected to the electrodes in such a way that it produces a predetermined measuring voltage between the electrodes, and

current measuring means connected to the electrodes for measuring an electrical current therebetween.

30. The device of claim 26, further comprising:

a voltage source connected to the electrodes in such a way that it produces a predetermined measuring voltage between the electrodes, and

current measuring means connected to the electrodes for measuring an electrical current therebetween.

31. The device of claim 6, wherein the voltage source is adapted to output an ac voltage with a predetermined time dependency.

32. The device of claim 27, wherein the current source is adapted to output an alternating current with a predetermined time dependency.

33. The device of claim 28, wherein the current source is adapted to output an alternating current with a predetermined time dependency.

34. The device of claim 29, wherein the voltage source is adapted to output an ac voltage with a predetermined time dependency.

35. The device of claim 30, wherein the voltage source is adapted to output an ac voltage with a predetermined time dependency.

36. The device of claim 31, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the current measuring means, which is modulated by the ac voltage produced by the voltage source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

37. The device of claim 32, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the voltage measuring means, which is modulated by the alternating current produced by the current source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

38. The device of claim 33, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the voltage measuring means, which is modulated by the alternating current produced by the current source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

39. The device of claim 34, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the current measuring means, which is modulated by the ac voltage produced by the voltage source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

40. The device of claim 35, further comprising:

a demodulation device, at an input of which in operation of the device is the measurement signal of the current measuring means, which is modulated by the ac voltage produced by the voltage source, the demodulation device being so designed that a signal can be taken off at an output, which corresponds in its configuration in respect of time to the envelope of the measurement signal or the positive or negative half-period of the measurement signal.

41. The device of claim 37, further comprising:

a filter stage for the removal of measurement signal components of a frequency of up to a maximum of 1 Hz.

42. The device of claim 39, further comprising:

a filter stage for the removal of measurement signal components of a frequency of up to a maximum of 1 Hz.

43. The device of claim 41, further comprising:

control means adapted to cause the evaluation unit to start or stop integration of a signal at the input of the evaluation unit.

44. The device of claim 42, further comprising:

control means adapted to cause the evaluation unit to start or stop integration of a signal at the input of the evaluation unit.

45. The device of claim 43, wherein the control means is so designed to cause the evaluation unit to effect integration respectively over the period of time of one or some cardiac periods.

46. The device of claim 44, wherein the control means is so designed to cause the evaluation unit to effect integration respectively over the period of time of one or some cardiac periods.

47. The device of claim 11, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

48. The device of claim 43, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

49. The device of claim 44, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

50. The device of claim 45, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

51. The device of claim 46, wherein the control means is designed to cause the evaluation unit to effect integration over at least one respective predeterminable period of time which is independent of the cardiac period duration.

52. The device of claim 50, wherein the evaluation unit has a memory.

53. The device of claim 51, wherein the evaluation unit has a memory.

54. The device of claim 52, wherein the evaluation unit is so designed that within the predetermined period of time the hitherto maximum and minimum signals at the input of the evaluation unit are continuously determined and stored in the memory, that at the end of the period of time the difference between the currently stored maximum and minimum signals is calculated and that at the beginning of a respective subsequent period of time the signals last stored in the preceding period of time are erased from the memory.

55. The device of claim 53, wherein the evaluation unit is so designed that within the predetermined period of time the hitherto maximum and minimum signals at the input of the evaluation unit are continuously determined and stored in the memory, that at the end of the period of time the difference between the currently stored maximum and minimum signals is calculated and that at the beginning of a respective subsequent period of time the signals last stored in the preceding period of time are erased from the memory.

56. The device of claim 54, wherein the control means is connected to the evaluation unit and designed to signal to the evaluation unit the beginning and the end of the predetermined period of time.

57. The device of claim 55, wherein the control means is connected to the evaluation unit and designed to signal to the evaluation unit the beginning and the end of the predetermined period of time.

58. The device of claim 56, wherein the control means is designed to cause the evaluation unit to effect integration and to determine the difference between the maximum and the minimum respectively within the same period of time.

59. The device of claim 57, wherein the control means is designed to cause the evaluation unit to effect integration and to determine the difference between the maximum and the minimum respectively within the same period of time.

60. The device of claim 58, wherein the evaluation unit is so designed that in operation of the device at the end of the respective period of time the evaluation unit outputs a signal which corresponds to the integral of the measurement signal over the period of time less the product of the duration of the period of time and the measurement signal minimum of the period of time.

61. The device of claim 59, wherein the evaluation unit is so designed that in operation of the device at the end of the respective period of time the evaluation unit outputs a signal which corresponds to the integral of the measurement signal over the period of time less the product of the duration of the period of time and the measurement signal minimum of the period of time.

62. The device of claim 60, further comprising:

a respective comparator connected to a reference value memory containing reference values and/or reference value ranges and which is so designed that in operation of the device the comparator compares the difference of the extreme values or the time integral of the measurement signal to a respective reference value or reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the reference value or reference value range or not and possibly what deviation is involved.

63. The device of claim 61, further comprising:

a respective comparator connected to a reference value memory containing reference values and/or reference value ranges and which is so designed that in operation of the device the comparator compares the difference of the extreme values or the time integral of the measurement signal to a respective reference value or reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the reference value or reference value range or not and possibly what deviation is involved.

64. The device of claim 60, further comprising:

a respective comparator connected to a reference value memory containing fluctuation reference values and/or fluctuation reference value ranges and which is so designed that in operation of the device the comparator compares the change in the difference of the extreme values or the time integral of the measurement signal in relation to the respectively precedingly determined value to a respective fluctuation reference value or fluctuation reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the fluctuation reference value or fluctuation reference value range or not and possibly what deviation is involved.

65. The device of claim 61, further comprising:

a respective comparator connected to a reference value memory containing fluctuation reference values and/or fluctuation reference value ranges and which is so designed that in operation of the device the comparator compares the change in the difference of the extreme values or the time integral of the measurement signal in relation to the respectively precedingly determined value to a respective fluctuation reference value or fluctuation reference value range contained in the reference value memory and produces an output signal which indicates whether the respective comparison result corresponds to a deviation from the fluctuation reference value or fluctuation reference value range or not and possibly what deviation is involved.

20. An implantable electrostimulation device for the treatment of tachycardiac rhythm disturbances comprising:

a detection unit;

a control unit;

a therapy unit for the treatment of tachycardiac rhythm disturbances adapted to produce a cardioversion or defibrillation electrotherapy to be applied to the heart,

wherein the detection unit comprises;

a measuring unit for picking up and reproducing a measurement signal corresponding to an intracardial impedance at an output thereof; and

an evaluation unit connected at an input to the measuring unit, and

wherein the control unit receives output signals from the evaluation unit and controls the activity of the measuring unit, the evaluation unit and the therapy unit, and

wherein the evaluation unit is adapted to determine and output a first signal which corresponds to the difference of a maximum and a minimum measured signal within at least one defined period of time, and

wherein the evaluation unit is additionally adapted to determine and output a second signal which is dependent on the integral of the measurement signal over at least one defined second period of time, and the first signal associated with the second period of time, wherein the first-mentioned period of time is before the second period of time or is identical to the second period of time.

21. The electrostimulation device of claim 20, wherein the therapy unit is so designed that it can also selectively apply a pacemaker electrostimulation therapy to the heart.

22. The electrostimulation device of claim 21, further comprising:

a signal pattern memory connected to the control unit and in which one or more control signals for the measuring unit, the evaluation unit and/or the therapy unit are associated with signal patterns, that is to say, output signals or combinations of output signals from the evaluation unit, and that the control unit is so designed that it compares output signals received from the evaluation unit to the signal patterns of the signal pattern memory and produces the control signals associated with the respectively correct signal pattern and transmits same to the corresponding unit.

23. The electrostimulation device of claim 22, wherein, for determining the control signals, the control unit additionally or exclusively accesses an assessment algorithm which is contained in a program memory and by means of which the control signals to be produced are computed in a computing unit on the basis of the output signals of the evaluation unit.

24. The electrostimulation device of claim 23, further comprising:

a housing which can be used as an electrode in the measurement of intracardial impedance.

66. The electrostimulation device of claim 20, further comprising:

a signal pattern memory connected to the control unit and in which one or more control signals for the measuring unit, the evaluation unit and/or the therapy unit are associated with signal patterns, that is to say, output signals or combinations of output signals from the evaluation unit, and that the control unit is so designed that it compares output signals received from the evaluation unit to the signal patterns of the signal pattern memory and produces the control signals associated with the respectively correct signal pattern and transmits same to the corresponding unit.

67. The electrostimulation device of claim 22, wherein, for determining the control signals, the control unit additionally or exclusively accesses an assessment algorithm which is contained in a program memory and by means of which the control signals to be produced are computed in a computing unit on the basis of the output signals of the evaluation unit.

68. The electrostimulation device of claim 23, further comprising:

a housing which can be used as an electrode in the measurement of intracardial impedance.

69. The electrostimulation device of claim 20, further comprising:

a housing which can be used as an electrode in the measurement of intracardial impedance.