Determining a patient's posture from mechanical vibrations of the heart

• US 8,012,098 B2
• Filed: 06/12/2009
• Issued: 09/06/2011
• Est. Priority Date: 07/28/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Siejko, Krzysztof Z., Maile, Keith R.
• Primary Examiner(s): BOCKELMAN, MARK
• Application Number:
  US12/484,108
• Publication Number:
  US 20090247889A1
• Time in Patent Office: 816 Days
• Field of Search: None
• US Class Current: 600/528
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: A61N 1/36535 controlled by body position or posture
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Abstract

A system for determining a patient'"'"'s posture by monitoring heart sounds. The system comprises an implantable medical device that includes a sensor operable to produce an electrical signal representative of heart sounds, a sensor interface circuit coupled to the sensor to produce a heart sound signal, and a controller circuit coupled to the sensor interface circuit. The heart sounds are associated with mechanical activity of a patient'"'"'s heart and the controller circuit is operable to detect a posture of the patient from a heart sound signal.

Claims

1. A method comprising:

sensing heart sounds associated with activity of a patient'"'"'s heart using an implantable medical device;

discriminating a posture of the patient from among a plurality of postures from the heart sounds; and

providing an indication of patient posture to a user or process.

2. The method of claim 1, wherein determining posture information of the patient from the heart sounds includes determining posture information from a frequency spectrum of the heart sounds.

3. The method of claim 2, wherein determining posture information from a frequency spectrum of the heart sounds includes performing a spectral analysis of energy of the heart sound signals to detect a change in the frequency spectrum.

4. The method of claim 3, wherein performing the spectral analysis includes calculating a fast Fourier transform.

5. The method of claim 1, wherein determining posture information of the patient from the heart sounds includes determining posture information from a magnitude of the heart sounds.

6. The method of claim 1, wherein determining posture information of the patient from the heart sounds includes:

determining a baseline for the heart sounds; and

detecting a change from the baseline.

7. The method of claim 1, wherein the method further includes detecting a change in posture.

8. The method of claim 1, wherein sensing heart sounds includes sensing one or a combination of S1 and S2 heart sounds.

9. The method of claim 8, wherein sensing heart sounds includes sensing heart sounds during a timing window, wherein a beginning of the timing window is determined in relation to a sensed cardiac event.

10. The method of claim 9, wherein sensing heart sounds during a timing window includes determining a patient specific timing window.

11. The method of claim 9, wherein sensing heart sounds during a timing window includes determining a timing window from data taken from a patient population.

12. The method of claim 1, wherein the method further includes:

determining patient physical activity information; and

determining a patient rest posture from the posture information and the activity information.

13. The method of claim 12, wherein determining patient physical activity information includes determining activity information using a heart rate of the patient.

14. The method of claim 12, wherein determining patient physical activity information includes sensing patient physical activity using an accelerometer.

15. The method of claim 12, determining patient physical activity information includes determining patient physical activity information from a same sensor used to sense heart sounds.

16. The method of claim 1, wherein the method further includes:

determining patient thoracic pressure information using the implantable medical device; and

using both the posture information and the thoracic pressure information to provide a congestive heart failure status indicator.

17. The method of claim 1, wherein the method further includes:

determining transthoracic impedance information using the implantable medical device; and

using both the posture information and the transthoracic impedance information to provide a congestive heart failure status indicator.

18. The method of claim 1, wherein sensing heart sounds includes sampling an electrical signal representative of the heart sounds and storing samples of the signal as heart sound data, and wherein determining posture information of the patient from the heart sounds includes transmitting the heart sound data from the implantable medical device to an external device and deriving posture information using the external device.

19. The method of claim 1, wherein sensing heart sounds includes sampling electrical signal representative of the heart sounds and storing samples of the signal as heart sound data, and wherein determining posture information of the patient from the heart sounds includes creating a histogram from the heart sound data.

20. The method of claim 1, wherein sensing heart sounds includes sampling an electrical signal representative of the heart sounds and storing samples of the signal as heart sound data, and wherein determining posture information of the patient from the heart sounds includes trending the heart sound data.