Method and apparatus for optimization of cardiac resynchronization therapy using heart sounds

• US 20060020294A1
• Filed: 06/10/2004
• Published: 01/26/2006
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Carlson, Gerrard M., Brockway, Marina, Lincoln, William C.
• Granted Patent: US 7,209,786 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: G06F 2218/00 Aspects of pattern recognition specially adapted for signal processing

Abstract

A cardiac rhythm management system provides for assessment of cardiac mechanical dyssynchrony based on heart sound morphology and optimization of pacing parameters based on the effect of pacing on the cardiac mechanical dyssynchrony assessment. A degree of cardiac mechanical dyssynchrony is measured by the time delay between tricuspid valve closure and mitral valve closure and/or the time delay between pulmonary valve closure and aortic valve closure. A cardiac resynchronization therapy is optimized by determining therapy parameters to provide an approximately minimum degree of cardiac mechanical dyssynchrony by cardiac pacing.

Claims

1. A system for analyzing a heart having a first cardiac valve and a second cardiac valve, the system comprising:

a heart sound input to receive one or more signals each indicative of heart sounds;

a heart sound detector, coupled to the heart sound input, to detect heart sounds of at least one predetermined type from the one or more signals; and

a computer-based heart sound morphology analyzer, coupled to the heart sound detector, to produce at least one dyssynchrony parameter indicative of a degree of cardiac mechanical dyssynchrony, the heart sound morphology analyzer including a heart sound measurement module to measure one or more parameters each based on at least one morphological feature of the heart sounds of the at least one predetermined type, the at least one morphological feature indicative of a time interval between closures of the first cardiac valve and the second cardiac valve in one cardiac cycle.

2. The system of claim 1, wherein the heart sounds of the at least one predetermined type comprise the first heart sounds (S1), and wherein the heart sound morphology analyzer comprises an S1 morphology analyzer to produce a first dyssynchrony parameter related to S1, the S1 morphology analyzer including an S1 measurement module to measure one or more parameters each based on at least an S1 morphological feature indicative a first time interval between a tricuspid valve closure and a mitral valve closure.

3. The system of claim 1, wherein the heart sounds of the at least one predetermined type comprise the second heart sounds (S2), and wherein the heart sound morphology analyzer comprises an S2 morphology analyzer to produce a second dyssynchrony parameter related to S2, the S2 morphology analyzer including an S2 measurement module to measure one or more parameters each based on at least an S2 morphological feature indicative of a second time interval between a pulmonary valve closure and an aortic valve closure.

4. The system of claim 1, wherein the heart sound input receives one or more signals indicative of first heart sounds (S1) and second heart sounds (S2), the heart sound detector detects S1 and S2, and the heart sound morphology analyzer comprises:

an S1 morphology analyzer to produce a first dyssynchrony parameter related to S1, the S1 morphology analyzer including an S1 measurement module to measure one or more parameters each based on at least an S1 morphological feature indicative a first measured time interval between a tricuspid valve closure and a mitral valve closure; and

an S2 morphology analyzer to produce a second dyssynchrony parameter related to S2, the S2 morphology analyzer including an S2 measurement module to measure one or more parameters each based on at least an S2 morphological feature indicative of a second measured time interval between a pulmonary valve closure and an aortic valve closure.

5. The system of claim 4, wherein the heart sound input comprise:

a right-ventricular heart sound input to receive a signal indicative of at least S1 sensed from a right ventricle (S1_RV) and S2 sensed from the right ventricle (S2_RV); and

a left-ventricular heart sound input to receive a signal indicative of at least S1 sensed from a left ventricle (S1_LV) and S2 sensed from the left ventricle (S2_LV), and wherein;

the S1 heart sound measurement module comprises an S1 delay measurement module to measure an S1 delay being a time interval between S1_RV and S1_LV; and

the S2 heart sound measurement module comprises an S2 delay measurement module to measure an S2 delay being a time interval between S2_RV and S2_LV.

6. The system of claim 5, further comprising a first implantable heart sensor adapted to sense the signal indicative of at least S1_RV and S2_RV and a second implantable heart sensor adapted to sense the signal indicative of at least S1_LV and S2_LV.

7. The system of claim 4, wherein:

the S1 heart sound measurement module comprises an S1 width measurement module to measure an S1 width; and

the S2 heart sound measurement module comprises an S2 width measurement module to measure an S2 width.

8. The system of claim 4, wherein

the S1 heart sound measurement module comprises an S1 delay measurement module to measure an S1 delay being a time interval between a morphological feature indicative of the tricuspid valve closure and a morphological feature indicative of the mitral valve closure;

and

the S2 heart sound measurement module comprises an S2 delay measurement module to measure an S2 delay being a time interval between a morphological feature indicative of the pulmonary valve closure and a morphological feature indicative of the aortic valve closure.

9. The system of claim 4, further comprising at least one implantable heart sound sensor to sense a signal indicative of at least S1 and S2.

10. The system of claim 9, further comprising an ensemble averaging circuit to ensemble average the signal indicative of at least S1 and S2.

11. The system of claim 4, further comprising a respiratory signal input to receive a respiratory signal indicative of an inspiratory phase and an expiratory phase of a respiratory cycle, and wherein at least the S2 heart sound measurement module is adapted to measure the one or more parameters during the expiratory phase.

12. The system of claim 11, further comprising an implantable respiratory sensor to sense the respiratory signal.

13. The system of claim 12, wherein the implantable respiratory sensor comprises an implantable accelerometer to sense an acceleration signal indicative of inspiration and expiration.

14. The system of claim 12, wherein the implantable respiratory sensor comprises an implantable impedance sensor to sense an impedance signal indicative of minute ventilation.

15. The system of claim 1, wherein the heart sound morphology analyzer comprises a heart sound time-frequency analyzer to produce at least one time-frequency representation for each of the one or more signals and produce the at least one dyssynchrony parameter based on the at least one time-frequency representation.

16. The system of claim 15, wherein the heart sound time-frequency analyzer is adapted to further produce a parameter indicative of pulmonary artery pressure based on at least one feature in the at least one time-frequency representation.

17. The system of claim 15, wherein the heart sound time-frequency analyzer comprises a short-time Fourier transform (STFT) module.

18. The system of claim 15, wherein the heart sound time-frequency analyzer comprises a reduced interference (RID) module.

19. The system of claim 15, wherein the heart sound time-frequency analyzer comprises a wavelet transform (WT) module.

20. The system of claim 1, further comprising a pacing parameter optimization module adapted to optimize one or more pacing parameters based on the at least one dyssynchrony parameter.

21. The system of claim 20, wherein the parameter optimization module is adapted to optimize one or more pacing parameters by adjusting the one or more pacing parameters for an approximately optimal value for the at least one dyssynchrony parameter, and wherein the pacing parameter optimization module comprises a parameter adjustment circuit to adjust the one or more pacing parameters.

22. The system of claim 21, wherein the parameter adjustment circuit comprises a pacing site selector to select one or more pacing sites to which pacing pulses are delivered.

23. The system of claim 21, wherein the parameter adjustment circuit comprises an atrioventricular delay (AVD) adjustment circuit to adjust one or more AVDs at which ventricular pacing pulses are delivered.

24. The system of claim 21, wherein the parameter adjustment circuit comprises an interventricular delay (IVD) adjustment circuit to adjust one or more IVDs at which ventricular pacing pulses are delivered.

25. The system of claim 20, further comprising:

a pacing circuit to deliver pacing pulses; and

a pacing controller, coupled to the pacing circuit and the pacing parameter optimization module,

wherein the pacing parameter optimization module comprises a pacing parameter generator to generate a plurality of pacing parameter sets each including one or more adjustable pacing parameters, and wherein the pacing controller is adapted to control a delivery of a plurality of the pacing pulse sequences each including a plurality of pacing pulses delivered using one pacing parameter set of the plurality of pacing parameter sets.

26. The system of claim 25, wherein the pacing parameter optimization module comprises an efficacy analyzer to relate each pacing parameter set of the plurality of pacing parameter sets to a value of the at least one dyssynchrony parameter.

27. The system of claim 26, wherein the pacing parameter optimization module further comprises an optimal parameter selector to select an optimal parameter set of the plurality of parameter sets, the optimal parameter set associated with a minimum value of the at least one dyssynchrony parameter.

28. The system of claim 25, wherein the pacing parameter generator comprises a pacing site generator to generate a plurality of pacing sites to one or more of which the pacing pulses are delivered.

29. The system of claim 25, wherein the pacing parameter generator comprises an atrioventricular delay (AVD) generator to generate a plurality of AVDs at which ventricular pacing pulses are delivered.

30. The system of claim 30, wherein the pacing parameter generator comprises an interventricular delay (IVD) generator to generate a plurality of IVDs at which ventricular pacing pulses are delivered.

31. A system for analyzing a heart having a first cardiac valve and a second cardiac valve, the system comprising:

an implantable system including;

one or more implantable heart sound sensors to sense one or more heart sound signals each indicative of heart sounds of at least one predetermined type; and

an implantable medical device including;

an implant controller, coupled to the one or more implantable heart sound sensors, to process the one or more heart sound signals; and

an implant telemetry module, coupled to the implantable controller, to transmit the one or more heart sound signals;

an external system communicatively coupled to the implantable medical device, the external system including;

an external telemetry module to receive the one or more heart sound signals; and

an external controller coupled to the external telemetry module, the external controller including a heart sound morphology analyzer to produce at least one dyssynchrony parameter indicative of a degree of cardiac mechanical dyssynchrony, the heart sound morphology analyzer including a heart sound measurement module to measure one or more parameters each based on at least one morphological feature of the heart sounds of the at least one predetermined type, the at least one morphological feature indicative of a time interval between closures of the first cardiac valve and the second cardiac valve in one cardiac cycle.

32. The system of claim 31, wherein the implantable medical device comprises a hermetically sealed housing, and wherein at least one of the one or more heart sound sensors are housed within the hermetically sealed housing.

33. The system of claim 31, wherein the implantable medical device comprises a pacing circuit, and the implantable system further comprises one or more pacing leads coupled to the pacing circuit, wherein at least one of the one or more heart sound sensors is incorporated into the one of the one or more pacing leads.

34. The system of claim 33, wherein the one or more pacing leads comprise a right ventricular (RV) pacing lead including at least an RV electrode and a left ventricular (LV) pacing lead include at least an LV electrode, wherein the one or more heart sound sensors comprise an RV heart sound sensor incorporated into the RV pacing lead near the RV electrode and an LV heart sound sensor incorporated into the LV pacing lead near the LV electrode.

35. The system of claim 31, wherein the one or more heart sound sensors comprise at least one accelerometer.

36. The system of claim 31, wherein the one or more heart sound sensors comprise at least one microphone.

37. The system of claim 31, wherein the implantable system further comprises a respiratory sensor to sense a respiratory signal indicative of respiratory cycles each including an inspiratory phase and expiratory phase, wherein the heart sound measurement module is adapted to measure the one or more parameters during the expiratory phase.

38. The system of claim 37, wherein the respiratory sensor comprises a minute ventilation impedance sensor incorporated onto the implantable medical device.

39. The system of claim 37, wherein the respiratory sensor comprises an accelerometer incorporated onto the implantable medical device.

40. The system of claim 31, wherein the external system comprise a patient monitoring system including:

an external device communicatively coupled to the implantable medical device via telemetry;

a telecommunication network coupled to the external device; and

a remote device, coupled to the telecommunication network, to allow communication with the implantable medical device from a remote location.

41. The system of claim 40, wherein the heart sound morphology analyzer is included in the remote device.

42. The system of claim 41, wherein the external controller further comprise a pacing parameter optimization module adapted to optimize one or more pacing parameters based on the at least the dyssynchrony parameter.

43. The system of claim 42, wherein the implantable medical device comprises a cardiac resynchronization therapy (CRT) device.

44. A method for operating a cardiac pacemaker, comprising:

receiving one or more heart sound signals indicative of heart sounds of at least one predetermined type;

detecting the heart sounds of the at least one predetermined type;

producing one or more dyssynchrony parameters each indicative of a degree of cardiac mechanical dyssynchrony based on at least one morphological feature of the detected heart sounds of the at least one predetermined type by executing an automated cardiac mechanical dyssynchrony algorithm; and

determining one or more pacing parameters for minimizing the degree of cardiac mechanical dyssynchrony based on the one or more dyssynchrony parameters.

45. The method of claim 44, further comprising sensing the one or more heart sound signals using one or more implantable heart sound sensors.

46. The method of claim 45, wherein sensing the one or more heart sound signals comprises sensing one or more heart sound signals each indicative of at least first heart sounds (S1) and second heart sounds (S2).

47. The method of claim 46, wherein sensing the one or more heart sound signals comprises sensing one or more acceleration signals.

48. The method of claim 46, wherein sensing the one or more heart sound signals comprises sensing one or more audio signals using one or more microphones.

49. The method of claim 46, wherein sensing the one or more heart sound signals comprises sensing a first heart sound signal from a right ventricle (RV) and sensing a second heart sound signal from a left ventricle (LV).

50. The method of claim 46, further comprising:

producing an envelope of each of the one or more heart sound signals by rectifying and low-pass filtering the each of the one or more heart sound signals; and

ensemble averaging each of the one or more heart sound signals to improve a signal-to-noise ratio of the each of the one or more heart sound signals.

51. The method of claim 46, wherein producing the one or more dyssynchrony parameters comprises producing a first dyssynchrony parameter related to S1 and producing a second dyssynchrony parameter related to S2.

52. The method of claim 51, further comprising:

receiving a respiratory signal indicative of respiratory cycles each including an inspiratory phase and expiratory phase; and

detecting the expiratory phase,

wherein producing the second dyssynchrony parameter related to S2 comprises producing the second dyssynchrony parameter related to S2 based on at least one morphological feature of S2 detected during the expiratory phase.

53. The method of claim 52, further comprising sensing the respiratory signal by sensing an thoracic impedance signal indicative minute ventilation.

54. The method of claim 52, further comprising sensing the respiratory signal by sensing an acceleration signal indicative of inspiration and expiration.

55. The method of claim 51, wherein producing the first dyssynchrony parameter related to S1 comprises measuring an S1 width, and producing the second dyssynchrony parameter related to S2 comprises measuring an S2 width.

56. The method of claim 51, wherein producing the first dyssynchrony parameter related to S1 comprises measuring an S1 delay representing a time interval between a tricuspid valve closure and a mitral valve closure during one cardiac cycle, and producing the second dyssynchrony parameter related to S2 comprises measuring an S2 delay representing delay between a pulmonary valve closure and an aortic valve closure during one cardiac cycle.

57. The method of claim 51, wherein producing the first dyssynchrony parameter related to S1 comprises producing a time-frequency representation of S1 and producing a first dyssynchrony parameter associated with at least one feature in the time-frequency representation of S1, and producing the first dyssynchrony parameter related to S2 comprises producing a time-frequency representation of S2 and producing a second dyssynchrony parameter associated with at least one feature in the time-frequency representation of S2.

58. The method of claim 57, further comprising producing a parameter indicative of pulmonary artery pressure based on at least the time-frequency representation of S2.

59. The method of claim 57, wherein producing the time-frequency representation of S1 and the time-frequency representation of S2 each comprise performing a short-time Fourier transform (STFT).

60. The method of claim 57, wherein producing the time-frequency representation of S1 and the time-frequency representation of S2 each comprise performing a reduced interference (RID).

61. The method of claim 57, wherein producing the time-frequency representation of S1 and the time-frequency representation of S2 each comprise performing a wavelet transform (WT).

62. The method of claim 51, wherein determining the one or more pacing parameters comprises optimizing the one or more pacing parameters based on at least the second dyssynchrony parameter.

63. The method of claim 62, wherein determining the one or more pacing parameters further comprises optimizing the one or more pacing parameters based on the first dyssynchrony parameter.

64. The method of claim 63, further comprising delivering pacing pulses using the one or more pacing parameters.

65. The method of claim 44, wherein determining the one or more pacing parameters comprises adjusting the one or more pacing parameters for an approximately optimal value of each of the one or more dyssynchrony parameters, the approximately optimal value being a value associated with an approximately minimum degree of cardiac mechanical dyssynchrony obtained by the adjusting the one or more pacing parameters.

66. The method of claim 65, wherein adjusting the one or more pacing parameters comprises selecting one or more pacing sites to which the pacing pulses are delivered.

67. The method of claim 65, wherein adjusting the one or more pacing parameters comprises adjusting one or more atrioventricular delays (AVDS) at which ventricular pacing pulses are delivered.

68. The method of claim 65, wherein adjusting the one or more pacing parameters comprises adjusting one or more interventricular delays (IVDs) at which ventricular pacing pulses are delivered.

69. The method of claim 44, wherein determining the one or more pacing parameters comprises:

generating a plurality of pacing parameter sets each including one or more adjustable pacing parameters;

delivering a plurality of the pacing pulse sequences each including a plurality of pacing pulses delivered using one pacing parameter set of the plurality of pacing parameter sets;

associating each pacing parameter set of the plurality of pacing parameter sets to a value of at least one of the one or more dyssynchrony parameters; and

selecting an optimal parameter set of the plurality of parameter sets, the optimal parameter set associated with an optimal value of at least one of the one or more dyssynchrony parameters, the optimal value associated with a minimum degree of cardiac mechanical dyssynchrony.

70. The method of claim 69, wherein generating the plurality of pacing parameter sets comprises generating a plurality of pacing sites to one or more of which the pacing pulses are delivered.

71. The method of claim 69, wherein generating the plurality of pacing parameter sets comprises generating a plurality of atrioventricular delays (AVDs) at which ventricular pacing pulses are delivered.

72. The method of claim 69, wherein generating the plurality of pacing parameter sets comprises generating a plurality of interventricular delays (IVDs) at which ventricular pacing pulses are delivered.