System and method for assessing cardiac performance through cardiac vibration monitoring

• US 20060155204A1
• Filed: 03/03/2006
• Published: 07/13/2006
• Est. Priority Date: 02/19/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Wariar, Ramesh, Carlson, Gerrard M.
• Granted Patent: US 8,025,624 B2
• Time in Patent Office: Days
• US Class Current: 600/528
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

A system and method for assessing cardiac performance through cardiac vibration monitoring is described. Cardiac vibration measures are directly collected through an implantable medical device. Cardiac events including at least one first heart sound reflected by the cardiac vibration measures are identified. The first heart sound is correlated to cardiac dimensional measures relative to performance of an intrathoracic pressure maneuver. The cardiac dimensional measures are grouped into at least one measures set corresponding to a temporal phase of the intrathoracic pressure maneuver. The at least one cardiac dimensional measures set is evaluated against a cardiac dimensional trend for the corresponding intrathoracic pressure maneuver temporal phase to represent cardiac performance.

Claims

1. A system for evaluating cardiac performance relative to performance of an intrathoracic pressure maneuver, comprising:

an implantable medical device to indirectly sense heart sounds by directly collecting cardiac vibration measures; and

an analysis component to evaluate cardiac functional changes to the heart sounds in response to performance of an intrathoracic pressure maneuver.

2. A system according to claim 1, wherein ventricular preload is measured to correct S1 heart sound intensity for preload variations.

3. A system according to claim 1, further comprising:

an evaluation component to evaluate the heart sounds to derive cardiac chamber pressure, wherein the cardiac chamber pressure comprises at least one of left ventricular ejection fraction, left ventricular end diastolic pressure, pulmonary capillary wedge pressure, pulmonary artery pressure, and an S3 index of pressure.

4. A system according to claim 1, wherein the implantable medical device comprises at least one of a cardiac pacemaker, cardioverter defibrillator, cardiac resynchronization device, cardiovascular monitor, and therapeutic device monitoring and treating structural problems of the heart.

5. A system according to claim 1, wherein heart sounds comprising cardiac events for at least one of intensity of a first heart sound, ratio of first heart sound energy to total energy, and ratio of first heart sound intensity to pulmonary artery pressure are determined.

6. A system according to claim 1, wherein the intrathoracic pressure maneuver comprises at least one of a Valsalva and Mü

ller maneuver.

7. A system according to claim 1, further comprising:

at least one of;

an evaluation subcomponent to evaluate at least one of overdamping and underdamping cardiac impedance response relative to normative levels; and

a notification subcomponent to generate a notification responsive to the at least one of overdamping and underdamping cardiac impedance response.

8. A system according to claim 1, wherein thoracic pressure is monitored during the intrathoracic pressure maneuver, further comprising:

an external pressure monitor to define a confined volume configured to receive at least one of a forced exhalation and a forced inhalation and to measure the thoracic pressure relative to the confined volume.

9. A system according to claim 1, wherein the cardiac vibrations are selected from the group comprising auscultatory, sub-audible, and detectable cardiac events.

10. A method for evaluating cardiac performance relative to performance of an intrathoracic pressure maneuver, comprising:

indirectly sensing heart sounds by directly collecting cardiac vibration measures through an implantable medical device; and

evaluating cardiac functional changes to the heart sounds in response to performance of an intrathoracic pressure maneuver.

11. A method according to claim 10, further comprising:

measuring ventricular preload to correct S1 heart sound intensity for preload variations.

12. A method according to claim 10, further comprising:

evaluating the heart sounds to derive cardiac chamber pressure, wherein the cardiac chamber pressure comprises at least one of left ventricular ejection fraction, left ventricular end diastolic pressure, pulmonary capillary wedge pressure, pulmonary artery pressure, and an S3 index of pressure.

13. A method according to claim 10, wherein the medical device comprises at least one of a cardiac pacemaker, cardioverter defibrillator, cardiac resynchronization device, cardiovascular monitor, and therapeutic device monitoring and treating structural problems of the heart.

14. A method according to claim 10, further comprising:

determining heart sounds comprising cardiac events for at least one of intensity of a first heart sound, ratio of first heart sound energy to total energy, and ratio of first heart sound intensity to pulmonary artery pressure.

15. A method according to claim 10, wherein the intrathoracic pressure maneuver comprises at least one of a Valsalva and Mü

ller maneuver.

16. A method according to claim 10, further comprising:

performing at least one of;

evaluating at least one of overdamping and underdamping cardiac impedance response relative to normative levels; and

generating a notification responsive to the at least one of overdamping and underdamping cardiac impedance response.

17. A method according to claim 10, further comprising:

monitoring thoracic pressure during the intrathoracic pressure maneuver;

defining a confined volume configured to receive at least one of a forced exhalation and a forced inhalation; and

measuring the thoracic pressure relative to the confined volume.

18. A method according to claim 10, wherein the cardiac vibrations are selected from the group comprising auscultatory, sub-audible, and detectable cardiac events.

19. A computer-readable storage medium holding code for performing the method of claim 10.

20. A system for assessing cardiac performance through cardiac vibration monitoring, comprising:

an implantable medical device to directly collect cardiac vibration measures;

a correlation component to identify cardiac events comprising at least one first heart sound reflected by the cardiac vibration measures, to correlate the first heart sound to cardiac dimensional measures relative to performance of an intrathoracic pressure maneuver, and to group the cardiac dimensional measures into at least one measures set corresponding to a temporal phase of the intrathoracic pressure maneuver; and

an analysis component to evaluate the at least one cardiac dimensional measures set against a cardiac dimensional trend for the corresponding intrathoracic pressure maneuver temporal phase to represent cardiac performance.

21. A system according to claim 20, further comprising:

an evaluation component to derive the cardiac dimensional measures by proportionately extrapolating an intensity of the first heart sound to a rate of rise of left ventricular pressure.

22. A system according to claim 20, further comprising:

an evaluation component to determine amplitude and frequency spectrum parameters for the cardiac events for at least one of intensity of the first heart sound, ratio of first heart sound acoustic energy to total acoustic energy, and ratio of first heart sound intensity to pulmonary artery pressure.

23. A system according to claim 20, further comprising:

an evaluation component to process the cardiac vibration measures by performing at least one of ensemble averaging, signal rectifying, and low-pass or band-pass filtering.

24. A system according to claim 20, wherein the cardiac dimensional measures comprise at least one of cardiac stroke volume, left ventricular ejection fraction, left ventricular end diastolic dimension, and left ventricular end systolic dimension.

25. A system according to claim 20, further comprising:

a history component to evaluate a history of cardiac performance representations; and

a trending component to recognize a trend within the history indicating at least one of cardiovascular disease absence, onset, progression, regression, and status quo.

26. A system according to claim 20, further comprising:

a characteristic signature formed with the cardiac dimensional trends over the performance of the intrathoracic pressure maneuver; and

a comparison component to compare an overall cardiac dimensional profile comprising the at least one cardiac dimensional measures set to the characteristic signature to form a cardiac performance assessment.

27. A system according to claim 20, further comprising:

at least one of;

a notification generated responsive to a substantially non-complying cardiac performance assessment; and

a programmer to program support to the implantable medical device.

28. A system according to claim 20, wherein the intrathoracic pressure maneuver is selected from the group comprising Valsalva and Mü

ller maneuvers, further comprising;

a collection component to collect the cardiac vibration measures relative to performance of the selected intrathoracic pressure maneuver.

29. A method for assessing cardiac performance through cardiac vibration monitoring, comprising:

directly collecting cardiac vibration measures through an implantable medical device;

identifying cardiac events comprising at least one first heart sound reflected by the cardiac vibration measures;

correlating the first heart sound to cardiac dimensional measures relative to performance of an intrathoracic pressure maneuver;

grouping the cardiac dimensional measures into at least one measures set corresponding to a temporal phase of the intrathoracic pressure maneuver; and

evaluating the at least one cardiac dimensional measures set against a cardiac dimensional trend for the corresponding intrathoracic pressure maneuver temporal phase to represent cardiac performance.

30. A method according to claim 29, further comprising:

deriving the cardiac dimensional measures by proportionately extrapolating an intensity of the first heart sound to a rate of rise of left ventricular pressure.

31. A method according to claim 29, further comprising:

determining amplitude and frequency spectrum parameters for the cardiac events for at least one of intensity of the first heart sound, ratio of first heart sound acoustic energy to total acoustic energy, and ratio of first heart sound intensity to pulmonary artery pressure.

32. A method according to claim 29, further comprising:

processing the cardiac vibration measures by performing at least one of ensemble averaging, signal rectifying, and low-pass or band-pass filtering.

33. A method according to claim 29, wherein the cardiac dimensional measures comprise at least one of cardiac stroke volume, left ventricular ejection fraction, left ventricular end diastolic dimension, and left ventricular end systolic dimension.

34. A method according to claim 29, further comprising:

evaluating a history of cardiac performance representations; and

recognizing a trend within the history indicating at least one of cardiovascular disease absence, onset, progression, regression, and status quo.

35. A method according to claim 29, further comprising:

forming a characteristic signature with the cardiac dimensional trends over the performance of the intrathoracic pressure maneuver; and

comparing an overall cardiac dimensional profile comprising the at least one cardiac dimensional measures set to the characteristic signature to form a cardiac performance assessment.

36. A method according to claim 29, further comprising:

performing at least one of;

generating a notification responsive to a substantially non-complying cardiac performance assessment; and

providing programming support to the implantable medical device.

37. A method according to claim 29, further comprising:

selecting the intrathoracic pressure maneuver from the group comprising Valsalva and Mü

ller maneuvers; and

collecting the cardiac vibration measures relative to performance of the selected intrathoracic pressure maneuver.

38. A computer-readable storage medium holding code for performing the method of claim 29.