Assessing heart failure status using morphology of a signal representative of arterial pulse pressure

• US 6,575,912 B1
• Filed: 10/16/2001
• Issued: 06/10/2003
• Est. Priority Date: 10/16/2001
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Turcott, Robert
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/981,570
• Time in Patent Office: 602 Days
• Field of Search: 600/476-480, 600/485, 600/486, 600/500-503, 600/504, 600/508
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

The heart failure (HF) status of a patient is determined based on the morphology of a signal representative of arterial pulse pressure. The signal can be a plethysmography signal that is produced by a implantable sensor or a non-implanted sensor. The signal can be produced by a chronically implantable sensor. In one embodiment, a time derivative signal is produced based on a signal representative of arterial pulse pressure. The time derivation signal can be used to determine maximum and minium peaks of,the signal representative of arterial pulse pressure. Alternatively, HF status can be assessed directly from the time derivative signal.

Claims

1. A method for assessing heart failure (HF) status of a patient, comprising the steps of:

(a) producing a plethysmography signal that is representative of arterial pulse pressure; and

(b) assessing HF status based on the shape of the plethysmography signal.

2. The method of claim 1, wherein step (a) comprises:

(a.1) transmitting light;

(a.2) receiving a portion of the light transmitted from the light source, the portion having an associated detected light intensity that is directly representative of blood volume, which is indirectly representative of the arterial pulse pressure; and

(a.3) producing the plethysmography signal based on the received portion of light.

3. The method of claim 1, wherein step (a) comprises:

(a.1) transmitting light, wherein an intensity of the transmitted light is based on a light control signal;

(a.2) receiving a portion of the transmitted light, the received portion having an associated detected light intensity;

(a.3) producing a feedback signal based on the received portion of light, the feedback signal indicative of the detected light intensity;

(a.4) comparing the feedback signal to a reference signal to produce a comparison signal;

(a.5) adjusting the light control signal based on the comparison signal; and

(a.6) producing the plethysmography signal based on at least one of the comparison signal and the light control signal.

4. The method of claim 1, wherein step (b) comprises triggering an alert indicator based on the shape of the plethysmography signal.

5. The method of claim 1, wherein step (b) comprises:

(b.1) determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal;

(b.2) determining a second value corresponding to the height of one or more secondary pulses of the plethysmography signal; and

(b.3) assessing the HF status based on the first and second values.

6. The method of claim 5, wherein step (b.3) comprises triggering an alarm based on the first and second values.

7. The method of claim 1, where step (b) comprises:

(b.1) determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal;

(b.2) determining a second value corresponding to the height of one or more dicrotic notches of the plethysmography signal; and

(b.3) assessing the HF status based on the first and second values.

8. The method of claim 7, wherein step (b.3) comprises triggering an alarm based on the first and second values.

9. The method of claim 1, wherein step (b) comprises:

(b.1) determining a first value corresponding to an area under one or more primary pulses of the plethysmography signal;

(b.2) determining a second value corresponding to an area under one or more secondary pulses of the plethysmography signal; and

(b.3) assessing the HF status based on the first and second values.

10. The method of claim 9, wherein step (b.3) comprises triggering an alarm based on the first and second values.

11. The method of claim 1, wherein step (b) comprises:

(b.1) producing a time derivative signal based on the plethysmography signal;

(b.2) locating maximum and minimum peaks of the plethysmography signal based on the time derivative signal;

(b.3) determining values that correspond to at least two located peaks of the plethysmography signal; and

(b.4) assessing the HF status based on the determined values.

12. The method of claim 11, wherein step (b.3) comprises determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more secondary pulses of the plethysmography signal.

13. The method of claim 11, wherein step (b.3) comprises determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more dicrotic notches of the plethysmography signal.

14. The method of claim 1, further comprising the steps of:

producing a cardiac electrical signal; and

wherein step (b) comprises assessing HF status based on a time between depolarization and at least one of a dicrotic notch, a primary pulse peak and a secondary pulse peak of the plethysmography signal, the depolarization being identified based on the cardiac electrical signal.

15. The method of claim 1, wherein step (b) further comprises tailoring drug therapy based on the shape of the signal.

16. A monitor for assessing heart failure (HF) status of a patient, comprising:

a light source and a light detector adapted to produce a plethysmography signal that is representative of arterial pulse pressure; and

means for assessing HF status based on the shape of the plethysmography signal.

17. The method of claim 16, wherein the means for assessing HF status comprises a microprocessor.

18. The monitor of claim 16, wherein:

the light source is adapted to transmit light;

the light detector is adapted to receive a portion of the light transmitted from the light source, the portion having an associated detected light intensity that is representative of the arterial pulse pressure, and to produce the plethysmography signal based on the received portion of light.

19. The method of claim 16, further comprising:

a light controller; and

a comparator,

wherein;

the light controller is adapted to produce a light control signal;

the light source is adapted to transmit light having an intensity that is based on the light control signal;

the light detector is adapted to

receive a portion of the light transmitted from the light source, the portion having an associated detected light intensity, and

produce a feedback signal based on the portion of light received at the light detector, the feedback signal indicative of the detected light intensity;

the comparator is adapted to compare the feedback signal to a reference signal to produce a comparison signal; and

the light controller also adapted to adjust the light control signal based on the comparison signal,

wherein the plethysmography signal produced from at least one of the comparison signal and the light control signal.

20. The monitor of claim 19, wherein the light source and the light detector are arranged in a reflection configuration.

21. The monitor of claim 20, wherein the light source and the light detector are located relatively adjacent to one another.

22. The monitor of claim 21, wherein the light source and the light detector are arranged such that a human appendage can be placed upon the light source and the light detector.

23. The monitor of claim 22, wherein the light source and the light detector are incorporated into an implantable device.

24. The monitor of claim 16, wherein the light source and light detector are arranged in a transmission configuration.

25. The monitor of claim 24, wherein the light source and the light detector are arranged such that a human appendage can be placed between the light source and the light detector.

26. The monitor of claim 16, further comprising an indicator alarm that is triggered based on the shape of the plethysmography signal.

27. The monitor of claim 16, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to the height of one or more primary pulses of the plethysmography signal;

determine a second value corresponding to the height of one or more secondary pulses of the plethysmography signal; and

assess the HF status based on the first and second values.

28. The monitor of claim 27, further comprising an indicator alarm that is triggered based on the first and second values.

29. The monitor of claim 16, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to the height of one or more primary pulses of the plethysmography signal;

determine a second value corresponding to the height of one or more dicrotic notches of the plethysmography signal; and

assess the HF status based on the first and second values.

30. The monitor of claim 29, further comprising an indicator alarm that is triggered based on the first and second values.

31. The monitor of claim 16, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to an area under one or more primary pulses of the plethysmography signal;

determine a second value corresponding to an area under one or more secondary pulses of the plethysmography signal; and

assess HF status based on the first and second values.

32. The monitor of claim 31, further comprising an indicator alarm that is triggered based on the first and second values.

33. The monitor of claim 16, further comprising a means for producing a time derivative signal based on the plethysmography signal;

and wherein the means for assessing HF status is adapted to

locate maximum and minimum peaks of the plethysmography signal based on the time derivative signal,

determine values that correspond to at least two peaks of the plethysmography signal, and

assess the HF status based on the determined values.

34. The monitor of claim 33, wherein the means for producing a time derivative signal comprises an analog filter.

35. The monitor of claim 33, wherein the means for assessing HF status is adapted to determine a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more secondary pulses of the plethysmography signal.

36. The monitor of claim 33, wherein the means for assess HF status is adapted to determine a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more dicrotic notches of the plethysmography signal.

37. A method for assessing heart failure (HF) status of a patient, comprising the steps of:

(a) producing a signal that is representative of arterial pulse pressure, the signal produced using a chronically implantable sensor; and

(b) assessing HF status based on the shape of the signal produced using the chronically implantable sensor.

38. The method of claim 37, wherein step (a) comprises producing the signal that is representative of arterial pulse pressure using an extravascular sensor.

39. The method of claim 37, wherein step (a) comprises producing a plethysmography signal that is representative of arterial pulse pressure using an extravascular sensor.

40. The method of claim 39, wherein the implantable sensor includes a light detector, and step (a) comprises:

(a.1) transmitting light from a light source;

(a.2) receiving, at the light detector, a portion of the light transmitted from the light source, the portion having an associated detected light intensity that is directly representative of blood volume, which is indirectly representative of the arterial pulse pressure; and

(a.3) producing the plethysmography signal based on the portion of light received at the light detector.

41. The method of claim 39, wherein the implanted sensor includes a light detector, and step (a) comprises:

(a.1) transmitting light from a light source, wherein an intensity of the transmitted light is based on a light control signal;

(a.2) receiving, at the light detector, a portion of the light transmitted from the light source, the portion having an associated detected light intensity;

(a.3) producing a feedback signal based on the portion of light received at the light detector, the feedback signal.indicative of the detected light intensity;

(a.4) comparing the feedback signal to a reference signal to produce a comparison signal;

(a.5) adjusting the light control signal based on the comparison signal; and

(a.6) producing the plethysmography signal based on at least one of the comparison signal and the light control signal.

42. The method of claim 37, wherein step (a) comprises producing the signal that is representative of arterial pulse pressure using an intra-vascular sensor.

43. The method of claim 37, wherein step (a) comprises producing the signal that is representative of arterial pulse pressure using an intra-vascular pressure sensor.

44. The method of claim 37, wherein step (b) comprises triggering an alert indicator based on the shape of the signal.

45. The method of claim 37, wherein step (b) comprises:

(b.1) determining a first value corresponding to the height of one or more primary pulses of the signal;

(b.2) determining a second value corresponding to the height of one or more secondary pulses of the signal; and

(b.3) assessing the HF status based on the first and second values.

46. The method of claim 45, wherein step (b.3) comprises triggering an alarm based on the first and second values.

47. The method of claim 37, where step (b) comprises:

(b.1) determining a first value corresponding to the height of one or more primary pulses of the signal;

(b.2) determining a second value corresponding to the height of one or more dicrotic notches of the signal; and

(b.3) assessing the HF status based on the first and second values.

48. The method of claim 47, wherein step (b.3) comprises triggering an alarm based on the first and second values.

49. The method of claim 37, wherein step (b) comprises:

(b.1) determining a first value corresponding to an area under one or more primary pulses of the signal;

(b.2) determining a second value corresponding to an area under one or more secondary pulses of the signal; and

(b.3) assessing the HF status based on the first and second values.

50. The method of claim 49, wherein step (b.3) comprises triggering an alarm based on the first and second values.

51. The method of claim 37, wherein step (b) comprises:

(b.1) producing a time derivative signal based on the plethysmography signal;

(b.2) locating maximum and minimum peaks of the plethysmography signal based on the time derivative signal;

(b.3) determining values that correspond to at least two located peaks of the plethysmography signal;

(b.4) assessing the HF status based on the determined values.

52. The method of claim 51, wherein step (b.3) comprises determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more secondary pulses of the plethysmography signal.

53. The method of claim 51, wherein step (b.3) comprises determining a first value corresponding to the height of one or more primary pulses of the plethysmography signal, and a second value corresponding to the height of one or more dicrotic notches of the plethysmography signal.

54. The method of claim 37, further comprising the steps of:

producing one of an electrogram or surface ECG signal; and

wherein step (b) comprises assessing HF status based on a time between depolarization and at least one of a dicrotic notch, a primary pulse peak and a secondary pulse peak of the signal representative of arterial pulse pressure, the depolarization being identified based on the one of the electrogram or surface ECG signal.

55. The method of claim 37, wherein step (b) further comprises tailoring drug therapy based on the shape of the signal.

56. A monitor for assessing heart failure (HF) status of a patient, comprising:

a chronically implantable sensor to produce a signal that is representative of arterial pulse pressure; and

means for assessing HF status based on the shape of the signal.

57. The monitor of claim 56, wherein the implantable sensor comprises an extravascular sensor.

58. The monitor of claim 57, wherein the signal comprises a plethysmography signal.

59. The monitor of claim 58, wherein the implantable sensor comprises a light detector, and further comprising a light source.

60. The monitor of claim 59, wherein the light source and the light detector are arranged in a reflection configuration.

61. The monitor of claim 60, wherein the light source and the light detector are located relatively adjacent to one another.

62. The monitor of claim 59, wherein:

the light source is adapted to transmit light; and

the light detector is adapted to receive a portion of the light transmitted from the light source, the portion having an associated detected light intensity that is representative of the arterial pulse pressure, and to produce the plethysmography signal based on the received portion of light.

63. The monitor of claim 59, further comprising:

a light controller; and

a comparator,

wherein;

the light controller is adapted to produce a light control signal;

the light source is adapted to transmit light having an intensity that is based on the light control signal;

the light detector is adapted to

receive a portion of the light transmitted from the light source, the portion having an associated detected light intensity, and

produce a feedback signal based on the portion of light received at the light detector, the feedback signal indicative of the detected light intensity;

the comparator is adapted to compare the feedback signal to a reference signal to produce a comparison signal; and

the light controller also adapted to adjust the light control signal based on the comparison signal,

wherein the plethysmography signal produced based on at least one of the comparison signal and the light control signal.

64. The monitor of claim 56, wherein the implantable sensor comprises an intra-vascular sensor.

65. The monitor of claim 56, wherein the intra-arterial sensor comprises a pressure transducer.

66. The monitor of claim 56, further comprising an alert indicator that is triggered based on the HF status.

67. The monitor of claim 65, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to the height of one or more primary pulses of the signal;

determine a second value corresponding to the height of one or more secondary pulses of the signal; and

assess the HF status based on the first and second values.

68. The monitor of claim 67, further comprising an indicator alarm that is triggered based on the first and second values.

69. The monitor of claim 56, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to the height of one or more primary pulses of the signal;

determine a second value corresponding to the height of one or more dicrotic notches of the signal; and

assess the HF status based on the first and second values.

70. The monitor of claim 69, further comprising an indicator alarm that is triggered based on the first and second values.

71. The monitor of claim 56, wherein the means for assessing HF status is adapted to:

determine a first value corresponding to an area under one or more primary pulses of the signal;

determine a second value corresponding to an area under one or more secondary pulses of the signal; and

assess HF status based on the first and second values.

72. The monitor of claim 71, further comprising an alert indicator that is triggered based on the first and second values.

73. A method for assessing heart failure (HF) status of a patient, comprising the steps of:

(a) producing a signal that is representative of arterial pulse pressure;

(b) producing a time derivative signal based on the signal produced at step (a); and

(c) assessing HF status based on the shape of the time derivative signal.

74. The method of claim 73, wherein step (a) comprises producing a plethysmography signal that is representative of arterial pulse pressure.

75. The method of claim 73, wherein step (c) further comprises tailoring drug therapy based on the shape of the signal.

76. The method of claim 73, wherein step (c) includes measuring the peak values attained by the time derivative signal.

77. The method of claim 73, wherein step (c) includes estimating the areas attained by the time derivative signal.

78. The method of claim 73, wherein step (c) includes measuring the times between zero crossings of the time derivative signal.

79. A monitor for assessing heart failure (HF) status of a patient, comprising:

a sensor to produce a signal that is representative of arterial pulse pressure;

a means for producing a time derivative signal based on the signal that is representative of arterial pulse pressure; and

means for assessing HF status based on the shape of the time derivative signal.

80. The monitor of claim 79, wherein the means for producing a time derivative signal comprises an analog filter.

81. The monitor of claim 79, wherein the means for assessing HF status comprises a microprocessor.

82. The monitor of claim 79, further comprising an alert indicator to indicated that a HF exacerbation has been detected.

83. The monitor of claim 79, wherein the signal representative of arterial pulse pressure comprises a plethysmography signal.