Dynamic spectral phonocardiograph

• US 4,967,760 A
• Filed: 02/02/1989
• Issued: 11/06/1990
• Est. Priority Date: 02/02/1989
• Status: Expired due to Fees

• Current Assignee: Yale University
• Original Assignee: Yale University
• Inventors: Bennett, Jean, Bennett, William R. Jr.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/306,137
• Time in Patent Office: 642 Days
• Field of Search: 128/715, 128/710, 128/712, 128/711, 128/699, 364/413.06
• US Class Current: 600/528
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

A system of generating a spectral phonocardiogram which summarizes time-dependent changes in the heart sounds throughout the heart cycle. The system is based on the projection of spectral surfaces of the Fourier transform of heart sounds as a function of time and is a useful diagnostic tool both for a cardiologist and a general practitioner. Permanent copies of the spectral phonocardiograms can provide useful records for monitoring the development of heart disease in a given individual. The system provides a useful means for rapid screening of large groups of people for heart disease by non-specialists in cardiology. A variant of the system provides automated computer diagnosis of the probable nature of the heart disease.

Claims

1. A method of producing a dynamic spectral cardiogram for picking out irregular sound patterns at different portions of a heart cycle as a function of frequency, comprising steps of:

a. producing real-time audio representation of a patient'"'"'s heart sounds; and

b. producing a three dimensional video display of the same heart sounds by generating projections of spectral surfaces of Fourier transforms of the heart sounds in real time.

2. The method according to claim 1, wherein the real time audio representation is produced by placing at least one microphone in the vicinity of a patient'"'"'s heart.

3. The method according to claim 1, wherein the video display is produced by placing at least one microphone in the vicinity of a patient'"'"'s heart to produce analog output signals corresponding to heart sounds, converting the analog output signals of the microphone to digital signals, performing a fast Fourier transform on the digital signals, and displaying the transforms as spectral surfaces on a display.

4. The method according to claim 3, wherein the step of producing the video display further comprises applying an adjustable resolution time-window weighting function, F, over a time interval of duration, T, to the digital signals, wherein F is described by

5. The method according to claim 4, wherein the second weighting function is an A-weighting function.

6. The method according to claim 4, wherein the second weighting function is a B-weighting function.

7. The method according to claim 4, wherein the second weighting function is a C-weighting function.

8. A method of producing a spectral cardiogram, comprising:

generating projections of spectral surfaces of Fourier transforms of heart sounds in real time, and displaying the spectral surfaces in a three dimensional display.

9. The method according to claim 8, wherein the projections are generated by placing at least one microphone in the vicinity of a patient'"'"'s heart to produce an analog output signal corresponding to heart sounds, converting the analog output signal to a digital signal, and performing a fast Fourier transform on the digital signal.

10. The method according to claim 9, wherein the step of generating the projections further comprises storing the digital signal on a video tape recorder.

11. The method according to claim 9, wherein the step of generating the projections further comprises storing the analog signal on a digital audio tape recorder.

12. The method according to claim 9, wherein the step of generating projections further comprises applying an adjustable resolution time-window weighting function, F, to the digital signal over a time-window of duration T, wherein F is described by

13. The method according to claim 12, wherein the second weighting function is an A-weighting function.

14. The method according to claim 12, wherein the second weighting function is a B-weighting function.

15. The method according to claim 12, wherein the second weighting function is a C-weighting function.

16. The method according to claim 8, wherein the step of displaying comprises displaying on a video monitor.

17. The method according to claim 8, wherein the step of displaying comprises displaying on a hard copy device.

18. A method of producing a dynamic spectral cardiogram for picking out irregular sound patterns at different portions of a heart cycle as a function of frequency, comprising:

a. means for producing a real-time audio representation of a patient'"'"'s heart sounds;

b. means for producing real time Fourier transforms of the audio representation of the heart sounds; and

c. means for producing a three dimensional video display of the same heart sounds by generating projections of spectral surfaces in real time of the Fourier transforms of the audio representation of the heart sounds

19. The device according to claim 18, wherein the means for producing real time audio representation comprises at least one microphone adapted to be placed in the vicinity of a patient'"'"'s heart.

20. The device according to claim 18, wherein the means for producing the video display comprises at least one microphone adapted to be placed in the vicinity of a patient'"'"'s heart to produce analog output signals corresponding to heart sounds, means for converting the analog output signals of the microphone to digital signals, means for performing a fast Fourier transform on the digital signals, and means for displaying the transforms as spectral surfaces on a display.

21. The method according to claim 20, wherein the means for producing the video display further comprises means for applying an adjustable resolution time-window weighting function, F, over a time interval of duration, T, to the digital signals, wherein F is described by

22. The device according to claim 21, wherein the second weighting function is an A-weighting function.

23. The device according to claim 21, wherein the second weighting function is a B-weighting function.

24. The device according to claim 21, wherein the second weighting function is a C-weighting function.

25. A device for producing a spectral cardiogram, comprising:

means receptive of audio representations of hear sounds for generating Fourier transfers thereof in real time, means for generating projections of spectral surfaces of the Fourier transforms of the Fourier transforms of the heart sounds in real time, and means for displaying the spectral surfaces in a three dimensional display.

26. The device according to claim 25, wherein the means for generating the projections comprises at least one microphone adapted to be placed in the vicinity of a patient'"'"'s heart to produce an analog output signal corresponding to heart sounds, means for converting the analog output signal to a digital signal, and means for performing a fast Fourier transform on the digital signal.

27. The device according to claim 26, wherein the means for generating the projections further comprises means for storing the digital signal on a video tape recorder.

28. The device according to claim 26, wherein the menas for generating the projections further comprises means for storing the analog signal on a digital audio tape recorder.

29. The device according to claim 26, wherein the means for generating projections further comprises means for applying an adjustable resolution time-window weighting function, F, to the digital signal over a time-window of duration T, wherein F is described by

30. The device according to claim 29, wherein the second weighting function is an A-weighting function.

31. The device according to claim 29, wherein the second weighting function is a B-weighting function.

32. The device according to claim 29, wherein the second weighting function is a C-weighting function.

33. The device according to claim 25, wherein the means for displaying comprises a video monitor.

34. The device according to claim 25, wherein the means for displaying comprises a hard copy device.