SYSTEMS AND METHODS FOR MODEL-BASED ESTIMATION OF CARDIAC EJECTION FRACTION, CARDIAC CONTRACTILITY, AND VENTRICULAR END-DIASTOLIC VOLUME

• US 20080294057A1
• Filed: 05/16/2008
• Published: 11/27/2008
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology, The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Heldt, Thomas, Mukkamala, Ramakrisna, Parlikar, Tushar A., Verghese, George C.
• Granted Patent: US 8,235,910 B2
• Time in Patent Office: Days
• US Class Current: 600/481
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

The methods and systems for estimating cardiac ejection fraction, cardiac contractility, and ventricular end-diastolic volume on a beat-by-beat basis include observing arterial blood pressure waveforms to determine ventricular compliances for a pressure-volume loop in the ventricle. Uncalibrated or calibrated cardiac ejection fraction may be calculated from estimates of stroke volume and the ventricular compliances. Cardiac contractility may be calculated from estimates of a ventricular compliance. Uncalibrated or calibrated ventricular end-diastolic volume may also be calculated from estimates of stroke volume and the ventricular compliances. A set of calibration parameters for calibrating cardiac ejection fraction or ventricular end-diastolic volume may be estimated in a least-squares manner.

Claims

1. A method for estimating beat-by-beat cardiovascular parameters and variables, comprising:

processing one or more cycles of arterial blood pressure to determine intra-beat and inter-beat variability in blood pressure; and

computing estimates of one or more cardiovascular parameters and variables from the intra-beat variability, the inter-beat variability, beat-by-beat estimates of stroke volume, and a ventricular pressure-volume model.

2. The method of claim 1, wherein actual measurements of the stroke volume are used instead of stroke volume estimates.

3. The method of claim 1, further comprising using information from phonocardiographic measurements.

4. The method of claim 3, wherein the phonocardiographic information includes parameters relating to the beat-by-beat timing of cardiac cycle events.

5. The method of claim 4, wherein the parameters relating to the beat-by-beat timing of cardiac cycle events include a duration of ventricular ejection.

6. The method of claim 1, wherein the cardiovascular parameters and variables include at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-diastolic compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance.

7. The method of claim 6, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, a beat-by-beat end-diastolic compliance, and a beat-by-beat peak-systolic compliance is for the left ventricle.

8. The method of claim 6, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, a beat-by-beat end-diastolic compliance, and a beat-by-beat peak-systolic compliance is for the right ventricle.

9. The method of claims 7 or 8, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance is estimated over a data window.

10. The method of claims 7 or 8, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance is estimated through optimization of an error criterion.

11. The method of claim 10, wherein the error criterion is least-squared error.

12. The method of claim 1, wherein the cardiovascular parameters and variables include an uncalibrated beat-by-beat ejection fraction.

13. The method of claim 12, further comprising computing calibrated beat-by-beat ejection fraction from the uncalibrated beat-by-beat ejection fraction using one or more calibration parameters.

14. The method of claim 13, wherein the calibration parameters are computed using an optimization criterion.

15. The method of claim 13, wherein the calibration parameters are computed for each of the beats.

16. The method of claim 13, wherein the calibration parameters include ventricular dead volume.

17. The method of claim 13, wherein the calibration parameters include intra-thoracic pressure.

18. The method of claim 1, wherein the cardiovascular parameters and variables include uncalibrated beat-by-beat end-diastolic volume.

19. The method of claim 18, further comprising computing calibrated beat-by-beat end-diastolic volume from the uncalibrated beat-by-beat end-diastolic volume using a second set of calibration parameters.

20. The method of claim 19, wherein the second set of calibration parameters is computed using an optimization criterion.

21. The method of claim 19, wherein the second set of calibration parameters is computed for each of the beats.

22. The method of claim 19, wherein the second set of calibration parameters include ventricular dead volume.

23. The method of claim 19, wherein the second set of calibration parameters include intra-thoracic pressure.

24. The method of claim 1, further comprising computing beat-by-beat cardiac contractility.

25. The method of claim 1, wherein the arterial blood pressure is measured at a central artery of the cardiovascular system.

26. The method of claim 25, wherein the central artery is the aorta.

27. The method of claim 1, wherein the arterial blood pressure is measured at a peripheral artery of the cardiovascular system.

28. The method of claim 1, wherein the arterial blood pressure is measured at a pulmonary artery of the cardiovascular system.

29. The method of claim 1, wherein the arterial blood pressure is measured using a noninvasive blood pressure device.

30. The method of claim 29, wherein the arterial blood pressure is measured using a photoplethysmographic blood pressure device.

31. The method of claim 29, wherein the arterial blood pressure is measured using a tonometric blood pressure device.

32. The method of claim 1, wherein processing the one or more cycles of arterial blood pressure includes obtaining a diastolic blood pressure;

a peak-systolic blood pressure; and

an end-systolic blood pressure for each cycle.

33. The method of claim 32, wherein the end-systolic blood pressure is estimated using an estimate of the duration of ventricular ejection.

34. The method of claim 33, wherein the estimate of the duration of ventricular ejection is obtained using phonocardiographic measurements.

35. The method of claim 1, wherein processing the one or more cycles of arterial blood pressure includes obtaining an onset time for each cycle.

36. The method of claim 1, wherein processing the one or more cycles of arterial blood pressure includes obtaining a beat duration for each cycle.

37. A system for estimating beat-to-beat cardiac output comprising:

a blood pressure measuring device;

a processor;

a display;

a user interface; and

a memory storing computer executable instructions, which when executed by the processor cause the processor to;

receive one or more cycles of arterial blood pressure from the blood pressure device;

receive beat-to-beat estimates of stroke volume;

analyze one or more cycles of arterial blood pressure to determine intra-beat and inter-beat variability in blood pressure;

compute estimates of one or more cardiovascular parameters and variables from the intra-beat variability, the inter-beat variability, beat-to-beat estimates of stroke volume, and a ventricular pressure-volume model; and

display the estimates.

38. The system of claim 37, wherein the computer executable instructions, when executed by the processor, cause the processor to compute the estimates of one or more cardiovascular system parameters and variables using actual measurements of the stroke volume instead of stroke volume estimates.

39. The system of claim 37, wherein the computer executable instructions, when executed by the processor, cause the processor to compute the estimates of one or more cardiovascular system parameters and variables using information from phonocardiographic measurements.

40. The system of claim 39, wherein the phonocardiographic information includes parameters relating to the beat-by-beat timing of cardiac cycle events.

41. The system of claim 40, wherein the parameters relating to beat-by-beat timing of cardiac cycle events include a duration of ventricular ejection.

42. The system of claim 37, wherein the cardiovascular parameters and variables include at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-diastolic compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance.

43. The system of claim 42, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, a beat-by-beat end-diastolic compliance, and a beat-by-beat peak-systolic compliance is for the left ventricle.

44. The system of claim 42, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, a beat-by-beat end-diastolic compliance, and a beat-by-beat peak-systolic compliance is for the right ventricle.

45. The system of claims 43 or 44, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance is estimated over a data window.

46. The system of claims 43 or 44, wherein the at least one of a beat-by-beat pre-ejection ventricular compliance, a beat-by-beat end-systolic ventricular compliance, and a beat-by-beat peak-systolic compliance is estimated through optimization of an error criterion.

47. The system of claim 46, wherein the error criterion is least-squared error.

48. The system of claim 37, wherein the cardiovascular parameters and variables include an uncalibrated beat-by-beat ejection fraction.

49. The system of claim 48, wherein the computer executable instructions, when executed by the processor, cause the processor to compute calibrated beat-by-beat ejection fraction from the uncalibrated beat-by-beat ejection fraction using one or more calibration parameters.

50. The system of claim 49, wherein the calibration parameters are computed using an optimization criterion.

51. The system of claim 49, wherein the calibration parameters are computed for each of the beats.

52. The system of claim 49, wherein the calibration parameters include ventricular dead volume.

53. The system of claim 49, wherein the calibration parameters include intra-thoracic pressure.

54. The system of claim 37, wherein the cardiovascular parameters and variables include uncalibrated beat-by-beat end-diastolic volume.

55. The system of claim 54, wherein the computer executable instructions, when executed by the processor, cause the processor to compute calibrated beat-by-beat end-diastolic volume from the uncalibrated beat-by-beat end-diastolic volume using a second set of calibration parameters.

56. The system of claim 54, wherein the second set of calibration parameters is computed using an optimization criterion.

57. The system of claim 54, wherein the second set of calibration parameters is computed for each of the beats.

58. The system of claim 54, wherein the second set of calibration parameters include ventricular dead volume.

59. The system of claim 54, wherein the second set of calibration parameters include intra-thoracic pressure.

60. The system of claim 37, wherein the computer executable instructions, when executed by the processor, cause the processor to compute beat-by-beat cardiac contractility.

61. The system of claim 37, wherein the blood pressure measuring device is located at a central artery of the cardiovascular system.

62. The system of claim 61, wherein the central artery is the aorta.

63. The system of claim 37, wherein the blood pressure measuring device is located at a peripheral artery of the cardiovascular system.

64. The system of claim 37, wherein the blood pressure measuring device is located at a pulmonary artery of the cardiovascular system.

65. The system of claim 37, wherein the blood pressure measuring device is a noninvasive blood pressure device.

66. The system of claim 65, wherein the noninvasive blood pressure device is a photoplethysmographic blood pressure device.

67. The system of claim 65, wherein the noninvasive blood pressure device is a tonometric blood pressure device.

68. The system of claim 37, wherein processing the one or more cycles of arterial blood pressure includes obtaining a diastolic blood pressure;

a peak-systolic blood pressure; and

an end-systolic blood pressure for each cycle.

69. The system of claim 68, wherein the end-systolic blood pressure is estimated using an estimate of the duration of ventricular ejection.

70. The system of claim 69, wherein the estimate of the duration of ventricular ejection is obtained using phonocardiographic measurements.

71. The system of claim 37, wherein processing the one or more cycles of arterial blood pressure includes obtaining an onset time for each cycle.

72. The system of claim 37, wherein processing the one or more cycles of arterial blood pressure includes obtaining a beat duration for each cycle.