Method and system for analyzing cardiovascular sounds

• US 7,517,319 B2
• Filed: 06/01/2004
• Issued: 04/14/2009
• Est. Priority Date: 06/02/2003
• Status: Expired due to Fees

• Current Assignee: Deep Breeze, Ltd.
• Original Assignee: Deep Breeze, Ltd.
• Inventors: Kushnir, Igal, Botbol, Meir
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): Heller; Tammie K
• Application Number:
  US10/857,451
• Publication Number:
  US 20040267149A1
• Time in Patent Office: 1,778 Days
• Field of Search: 600/528, 600/586, 600/493, 600/514
• US Class Current: 600/528
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

A method and system for analyzing sounds originating in at least a portion of an individual'"'"'s cardiovascular system. N transducers, where N is an integer, are fixed on a surface of the individual over the thorax. The ith transducer is fixed at a location x_i and generates an initial signal P(x_i,i) indicative of pressure waves at the location x_i, for i=1 to N. the signals P(x_i,t) are processed so as to generate filtered signals in which at least one component of the signals P(x_i,t)not arising from cardiovascular sounds has been removed. The filtered signals may be used for generating an image of the at least portion of the cardiovascular system.

Claims

1. A system for analyzing sounds originating in at least a portion of an individual'"'"'s cardiovascular system comprising:

(One) N transducers, where N is an integer, each transducer configured to be fixed on a surface of the individual over the thorax, the ith transducer being fixed at a location x_i and generating an initial signal P(x_i,t) indicative of pressure waves at the location x_i, for i=1 to N; and

(Two) a processor configured to receive the signals P(x_i,t) and to filter the signals P(x_i,t) so as to generate filtered signals in which at least one component of the signals P(x_i,t) not arising from cardiovascular sounds has been removed

wherein respiratory tract sounds have been removed, and

wherein the processor is further configured to determine an average acoustic energy {tilde over (P)} (x,t₁,t₂) arising from the cardiovascular system at at least one position x over a time interval from a first time t₁ to a second time t₂, {tilde over (P)} being determined in an algorithm involving at least one of the processed signals,

wherein the function {tilde over (P)} is determined at one or more locations x in an algorithm comprising;

(One) determining an average acoustic energy {tilde over (P)} (x_i,t₁,t₂) over a time interval from t₁ to t₂ at a plurality of locations x_i of transducers; and

(Two) determining an average acoustic energy {tilde over (P)} (x,t₁, t₂) at at least one location x by interpolation of the determined {tilde over (P)} (x_i,t₁, t₂).

2. The method according to claim 1 wherein the initial signals are filtered by a band pass filter passing between 15 to 45 Hz.

3. The system according to claim 1 wherein the processor is further configured to generate an image of the at least portion of the cardiovascular system from at least one of the filtered signals.

4. The system according to claim 3 wherein the processor is further configured to display an image of the at least portion of the cardiovascular system on a display device.

5. The system according to claim 1 wherein the processor is configured to generate an image of the at least portion of the cardiovascular system at a plurality of times or over a plurality of successive time intervals, and to display the images successively on a display device.

6. The system according to claim 1 further comprising a two-dimensional display device.

7. The system according to claim 1 wherein the processor is further configured to compare the average acoustic energy {tilde over (P)} to one or more predetermined functions {tilde over (F)} and determine a function {tilde over (F)}₀ from among the functions {tilde over (F)} most similar to {tilde over (P)}.

8. The system according to claim 7 wherein the processor is further configured to make a diagnosis based upon the determined function.

9. The system according to claim 1 wherein the average acoustic energy {tilde over (P)} over a time interval from t₁ to t₂ is determined at a location x_i of a transducer using the algebraic expression:

$\tilde{P}<br><br>\left(x_i,t_1,t_2\right)={\int <br><br>}_{t_1}^{t_2}<br><br>P^2<br><br>\left(x_i,t\right)<br><br>d<br><br>t.$

10. The system according to claim 1 wherein the average acoustic energy is determined at at least one location x by interpolation of the determined {tilde over (P)} (x_i,t₁,t₂) using the algebraic expression:

$\begin{array}{cc}\tilde{P}<br><br>\left(x,t_1,t_2\right)=\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>\tilde{P}<br><br>\left(x_i,t_1,t_2\right)<br><br><br><br>g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)& \left(2\right)\end{array}$

where g(x,x_i,σ

) is a kernel satisfying

$\begin{array}{cc}{\nabla <br><br>}^2<br><br>g=\frac{\partial <br><br>g}{\partial <br><br>\mathrm{\sigma <br><br>}}& \left(3\right)\\ \underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)<br><br><br><br>\mathrm{is}<br><br><br><br>\mathrm{approximately}<br><br><br><br>\mathrm{equal}<br><br><br><br>\mathrm{to}<br><br><br><br>1.& \left(4\right)\end{array}$

11. The system according to claim 10 wherein g(x,ν

_i,σ

) is the kernel

$\begin{array}{cc}g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)=\mathrm{Exp}-\left(\frac{{\left(x^1-x_i^1<br><br>\sqrt{\mathrm{\sigma <br><br>}}\right)}^2}{2<br><br><br><br>\mathrm{\sigma <br><br>}}\right)·<br><br>\mathrm{Exp}-\left(\frac{{\left(x^2-x_i^2<br><br>\sqrt{\mathrm{\sigma <br><br>}}\right)}^2}{2<br><br><br><br>\mathrm{\sigma <br><br>}}\right).& \left(5\right)\end{array}$

12. The system according to claim 8 wherein the processor is further configured to display the average acoustic energy {tilde over (P)} (x,t₁,t₂) on a display device.

13. The system according to claim 1 wherein the processor is configured to determine an average acoustic energy over a plurality of successive time intervals, each average acoustic energy being determined using an algorithm involving at least one of the signals P(x_i,t).

14. The system according to claim 13 wherein the processor is configured to sequentially display on a display device a representation of each determined average acoustic energy.

15. The system according to claim 1, wherein the processor is further configured to

subject the signals P(x_i,t₁,t₂) to band pass filtering in each of one or more frequency bands;

and

determine the average acoustic energy function for each frequency band based upon at least one of the filter signals.

16. The system according to claim 15 wherein the processor is configured to display one or more of the average acoustic energy functions determined for a frequency band on a display device.

17. A method for analyzing sounds originating in at least a portion of an individual'"'"'s cardiovascular system comprising:

(One) fixing on a surface of the individual over the thorax, N transducers, where N is an integer, and for i=1 to N, the ith transducer being fixed at a location x_i and generating an initial signal P(x_i, t) indicative of pressure waves at the location x_i;

(Two) processing the signals P(x_i,t) so as to generate filtered signals in which at least one component of the signals P(x_i,t) not arising from cardiovascular sounds has been removed and

(Three) determining an average acoustic energy {tilde over (P)} (x,t₁,t₂) arising from the cardiovascular system at at least one position x over a time interval from a first time t₁ to a second time t₂, {tilde over (P)} being determined in an algorithm involving at least one of the processed signals,

wherein the function {tilde over (P)} is determined at one or more locations x in an algorithm comprising;

(One) determining an average acoustic energy {tilde over (P)} (x_i,t₁,t₂) over a time interval from t₁ to t₂ at a plurality of locations x_i of transducers; and

(Two) determining an average acoustic energy {tilde over (P)} (x,t₁,t₂) at at least one location x by interpolation of the determined {tilde over (P)} (x_i,t₁,t₂).

18. The method according to claim 17 wherein respiratory tract sounds are filtered from the initial signals.

19. The method according to claim 17 wherein the initial signals are filtered by a band pass filter passing between 15 to 45 Hz.

20. The method according to claim 17 further comprising generating an image of the at least portion of the cardiovascular method from at least one of the filtered signals.

21. The method according to claim 20 further comprising displaying an image of the at least portion of the cardiovascular system on a display device.

22. The method according to claim 17 further comprising generating an image of the at least portion of the cardiovascular method at a plurality of times or over a plurality of successive time intervals, and displaying the images successively on a display device.

23. The method according to claim 17 further comprising comparing the average acoustic energy {tilde over (P)} to one or more predetermined functions {tilde over (F)} and determining a function {tilde over (F)}₀ from among the functions {tilde over (F)} most similar to {tilde over (P)}.

24. The method according to claim 23 wherein the processor is further configured to make a diagnosis based upon the determined function.

25. The method according to claim 17 wherein the average acoustic energy {tilde over (P)} (x_i,t₁,t₂) is determined over a time interval from t₁ to t₂ at a plurality of locations x_i of transducers using the algebraic expression:

$\tilde{P}<br><br>\left(x_i,t_1,t_2\right)={\int <br><br>}_{t_2}^{t_2}<br><br>P^2<br><br>\left(x_i,t\right)<br><br>d<br><br>t.$

26. The method according to claim 17 wherein the average acoustic energy is determined at at least one location x by interpolation of the determined {tilde over (P)} (x_i,t₁,t₂) using the algebraic expression:

$\begin{array}{cc}\tilde{P}<br><br>\left(x_i,t_1,t_2\right)=\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>\tilde{P}<br><br>\left(x_i,t_1,t_2\right)<br><br>g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)& \left(2\right)\end{array}$

where g(x,x_i,σ

) is a kernel satisfying

$\begin{array}{cc}{\nabla <br><br>}^2<br><br>g=\frac{\partial <br><br>g}{\partial <br><br>\mathrm{\sigma <br><br>}}& \left(3\right)\\ \underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)<br><br><br><br>\mathrm{is}<br><br><br><br>\mathrm{approximately}<br><br><br><br>\mathrm{equal}<br><br><br><br>\mathrm{to}<br><br><br><br>1.& \left(4\right)\end{array}$

27. The method according to claim 26 wherein g(x,ν

_i,σ

) is the kernel

$\begin{array}{cc}g<br><br>\left(x,x_i,\mathrm{\sigma <br><br>}\right)=\mathrm{Exp}-\left(\frac{{\left(x^1-x_i^1<br><br>\sqrt{\mathrm{\sigma <br><br>}}\right)}^2}{2<br><br>\mathrm{\sigma <br><br>}}\right)·<br><br>\mathrm{Exp}-\left(\frac{{\left(x^2-x_i^2<br><br>\sqrt{\mathrm{\sigma <br><br>}}\right)}^2}{2<br><br>\mathrm{\sigma <br><br>}}\right).& \left(5\right)\end{array}$

28. The method according to claim 17 further comprising displaying the average acoustic energy {tilde over (P)} (x,t₁,t₂) on a display device.

29. The method according to claim 17 further comprising determining an average acoustic energy over a plurality of successive time intervals, each average acoustic energy being determined using an algorithm involving at least one of the signals P(x_i,t).

30. The method according to claim 29 further comprising sequentially displaying on a display device a representation of each determined average acoustic energy.

31. The method according to claim 17 further comprising determining an average acoustic energy over a plurality of successive time intervals, each average acoustic energy being determined using an algorithm involving at least one of the signals P(x_i,t).

32. The method according to claim 17 further comprising:

subjecting the signals P(x_i,t₁,t₂) to band pass filtering in each of one or more frequency bands; and

determining the average acoustic energy function for each frequency band based upon at least one of the filter signals.

33. The method according to claim 32 further comprising displaying one or more of the average acoustic energy functions determined for a frequency band on a display device.

34. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for analyzing sounds originating in at least a portion of an individual'"'"'s cardiovascular system, comprising:

processing N initial signals P(x_i,t), where N is an integer, the initial signals being indicative of pressure waves at a location x_i;

for i=1 to N, so as to generate filtered signals in which at least one component of the signals P(x_i,t) not arising from cardiovascular sounds has been removed and

determining an average acoustic energy {tilde over (P)} (x,t₁,t₂) arising from the cardiovascular system at at least one position x over a time interval from a first time t₁ to a second time t₂, {tilde over (P)} being determined in an algorithm involving at least one of the processed signals,

wherein the average acoustic energy {tilde over (P)} over a time interval from t₁ to t₂ is determined at a location x_i of a transducer using the algebraic expression;

$\tilde{P}<br><br>\left(x_i,t_1,t_2\right)={\int <br><br>}_{\mathrm{t1}}^{\mathrm{t2}}<br><br>P^2<br><br>\left(x_i,t\right)<br><br>d<br><br>t.$

35. A computer program product comprising a computer useable medium having computer readable program code embodied therein for analyzing sounds originating in at least a portion of an individual'"'"'s cardiovascular system, comprising:

processing N initial signals {tilde over (P)}(x_i, t), where N is an integer, the initial signals being indicative of pressure waves at a location x_i, for i=1 to N, so as to generate filtered signals in which at least one component of the signals P(x_i, t) not arising from cardiovascular sounds has been removed and

determining an average acoustic energy {tilde over (P)} (x,t₁,t₂) arising from the cardiovascular system at at least one position x over a time interval from a first time t₁ to a second time t₂, {tilde over (P)} being determined in an algorithm involving at least one of the processed signals,

wherein the average acoustic energy {tilde over (P)} over a time interval from t₁ to t₂ is determined at a location x_i, of a transducer using the algebraic expression;

$\tilde{P}<br><br>\left(x_i,t_1,t_2\right)={\int <br><br>}_{t<br><br><br><br>1}^{t<br><br><br><br>2}<br><br>P^2<br><br>\left(x_i,t\right)<br><br><br><br>d<br><br>t.$