U.S. patent number RE38,159 [Application Number 09/802,080] was granted by the patent office on 2003-06-24 for non-invasive method and apparatus for diagnosing and monitoring aortic valve abnormalities, such as aortic regurgitation.
This patent grant is currently assigned to Pulse Metric, Inc.. Invention is credited to Todd Brinton, Shiu-Shin Chio.
United States Patent |
RE38,159 |
Chio , et al. |
June 24, 2003 |
Non-invasive method and apparatus for diagnosing and monitoring
aortic valve abnormalities, such as aortic regurgitation
Abstract
A method and device is provided for determining aortic valve
abnormalities. The method first includes the step of providing a
sphygmomanometer device for inducing a pressure on a body part of a
patient. A data stream receiver is provided for receiving a stream
of data relating to the pressure response of the pulsed fluid
flowing through the cardiovascular system of the patient. A data
processor is provided for processing the data to create a series of
time dependant pulse wave forms. The data can be converted by Fast
Fourier Transformation (FFT) to obtain Power Spectrum (PS) which
comprises a frequency dependant array of pulse signals. Both of the
time dependant and frequency dependant (Power Spectrum) data can be
displayed and analyzed to help determine the condition of the
aortic valve and the percentage of regurgitation of the patient.
With the Power Spectrum display, the determination is made based on
first, identifying the existence of an additional second series of
harmonically occurring regurgitation signals that have a frequency
different from the main signals indicative of the forward flow of
fluid through the aortic valve. The ratio of the amplitude or
density of the regurgitation signal peak can be divided by the
amplitude or density of the associated main signal peak, to
determine the ratio of the associated "Regurgitation" flow to and
"Main" flow, to thereby semi-quantitatively determine the percent
of regurgitation flow of the patient.
Inventors: |
Chio; Shiu-Shin (Rancho Santa
Fe, CA), Brinton; Todd (Sunnyvale, CA) |
Assignee: |
Pulse Metric, Inc. (San Diego,
CA)
|
Family
ID: |
26687722 |
Appl.
No.: |
09/802,080 |
Filed: |
March 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
816988 |
Mar 13, 1997 |
05879307 |
Mar 9, 1999 |
|
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Current U.S.
Class: |
600/485;
600/500 |
Current CPC
Class: |
A61B
5/02116 (20130101); A61B 5/022 (20130101); A61B
5/02225 (20130101); A61B 5/029 (20130101); A61B
5/7257 (20130101) |
Current International
Class: |
A61B
5/026 (20060101); A61B 5/022 (20060101); A61B
5/029 (20060101); A61B 005/00 () |
Field of
Search: |
;600/485,493-7,500-3 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Shiota, Takahiro, M.D. et al; Effective Regurgitant Orifice Area by
the Color Doppler Flow Convergence Method for Evaluating the
Severity of Chronic Aortic Regurgitation; Feb. 1, 1996;
Circulation, vol. 93, No. 3, pp. 594-602. .
Ishii, Masahiro, M.D. et al.; Evaluation of eccentric aortic
regurgitation by color Doppler jet and color Doppler-imaged vena
contracta measurements: An animal study of quantified aortic
regurgitation; Oct., 1996; American Heart Journal; pp. 796-804.
.
Tamai, Takuya, M.D. et al.; Evaluation of Aortic Regurgitation
Using Cine Magnetic Resonance Imaging; Nov., 1993; Japan Heart
Journal; pp. 741-748..
|
Primary Examiner: Nasser; Robert L.
Attorney, Agent or Firm: Indiano, Vaughan & Roberts,
P.A.
Parent Case Text
This patent application is a continuation-in-part of provisional
patent application No. 60/015,719, filed on 15 Mar. 1996.
Claims
What is claimed is:
1. A method for identifying the existence of aortic valve
abnormalities in a patient comprising the steps of: (1) providing a
non-invasive pressure inducing means for inducing a pressure on a
body part of a patient and applying pressure to the body part; (2)
providing a data receiving means; (3) using the data receiving
means to receive a stream of pulsation signal data from the patient
relating to the pressure response of pulsed fluid flowing through
the cardiovascular system of the patient; (4) providing a data
processing means; (5) using the data processing means for
processing the stream of pulsation signal data to create an array
of pulse wave forms; and (6) identifying wave form characteristics
that denote the presence of aortic valve abnormalities.
2. The method of claim 1 wherein the step of using the data
processing means comprises the step of using the data processing
means to create a time dependant array of pulse wave forms.
3. The method of claim 2 wherein each of the pulse wave forms of
the time dependant array of pulse wave forms includes a peak, and
the step of identifying wave form characteristics includes the step
of comparing the height of a series of adjacent wave form
peaks.
4. The method of claim 3 wherein the step of comparing the height
of a series of adjacent wave form peaks includes the step of
comparing the height of at least four adjacent peaks, P.sub.1,
P.sub.2, P.sub.3 and P.sub.4, having heights of H.sub.1, H.sub.2,
H.sub.3 and H.sub.4, respectively.
5. The method of claim 4 further comprising the step of detecting
the presence of aortic valve abnormalities if at least one of (1):
H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3 >H.sub.4 ;
and (2): H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and H.sub.3
<H.sub.4 occurs.
6. The method of claim 1 wherein the array of pulse wave forms
comprises a series of at least four adjacent pulse wave forms
including a first wave form having a peak P.sub.1, and a height
H.sub.1 ; a second pulse wave form having a peak P.sub.2 and a
height H.sub.2 ; a third pulse wave form having a peak P.sub.3 and
a height H.sub.3 ; and a fourth pulse wave form having a peak
P.sub.4 and a height H.sub.4 ; further comprising the step of
detecting the presence of aortic valve abnormalities if at least
one of: (1) H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3
>H.sub.4 ; and (2) H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and
H.sub.3 <H.sub.4 occurs.
7. The method of claim 1 further comprising the step of graphically
displaying the array of pulse wave forms.
8. The method of claim 7 wherein (1) the step of using the data
processing means comprises the step of using the data processing
means to create a time dependant array of pulse wave forms, (2) the
time dependant array of pulse wave forms are graphically displayed,
(3) the time dependant array of pulse wave forms being graphically
displayed include a series of pulse wave forms each having a peak,
(4) the step of graphically displaying the time dependant array
includes the step of displaying an envelope line that extends
between the peaks of adjacent wave forms, and (5) the step of
identifying wave form characteristics includes the step of
identifying the slope of the envelope line to determine whether it
denotes the presence of aortic valve abnormalities.
9. A method for identifying the existence of aortic valve
abnormalities, comprising the steps of: (1) providing a
non-invasive pressure inducing means for inducing a pressure on a
body part of a patient and applying pressure to the body part; (2)
providing a data receiving means; (3) using the data receiving
means to receive a stream of pulsation signal data from the patient
relating to the pressure response of pulsed fluid flowing through
the cardiovascular system of the patient having a cardiovascular
system; (4) providing a data processing means; (5) processing the
stream of pulsation signal data to create an array of time
dependant wave form data; (6) converting the array of time
dependant wave form data to an array of frequency dependant wave
form data; and (7) identifying characteristics of the frequency
dependant wave form data that denote the presence of aortic valve
abnormalities.
10. The method of claim 9 wherein the steps of converting the time
dependant wave form data comprises the step of using a Fourier
transformation to convert the time dependant wave form data to
frequency dependant wave form data.
11. The method of claim 9 wherein the step of identifying the
characteristics of the frequency dependant wave form data includes
the step of identifying a first series of harmonically occurring
flow signals corresponding to a flow of fluid forwardly through the
aortic valve, and detecting the presence or absence of a second
series of harmonically occurring flow signals corresponding to
aortic regurgitation.
12. The method of claim 11 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has an amplitude
A.sub.1, and each of the flow signals of the second series has an
amplitude A.sub.2 and further comprising the step of comprising the
amplitude A.sub.2 of a flow signal of the second series to the
amplitude A.sub.1 of a flow signal of the first series to obtain a
semi-quantitative analysis of the aortic regurgitation.
13. The method of claim 12 wherein the step of comparing the
amplitudes comprises the step of determining a ratio A.sub.2
/A.sub.1 of the amplitudes of corresponding flow signals of the
second and first series to approximate the ratio of aortic
regurgitation flow to forward fluid flow through the aortic
valve.
14. The method of claim 11 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has a density, D.sub.1
each of the flow signals of the second series has a density,
D.sub.2 and further comprising the step of comprising the density
D.sub.2 of the flow signal of the second series to the density
D.sub.1 of the flow signal of the first series to obtain a
semi-quantitative value of the aortic regurgitation.
15. The method of claim 14 wherein the step of comparing the
densities comprises the step of determining the ratio D.sub.2
/D.sub.1 of corresponding flow signals of the second and first
series to approximate the ratio of aortic regurgitation flow, to
the flow of fluid forward through the aortic valve.
16. The method of claim 11 further comprising the step of
evaluating the frequency shift between the flow signals of the
first series and the flow signals of the second series.
17. The method of claim 16 wherein the step of evaluating the
frequency shift comprises the step of evaluating the frequency
shift between the flow signals of the first series and the flow
signals of the second series to determine at least one of the
nature, type and characteristics of the aortic regurgitation of the
patient.
18. A device for identifying the existence of aortic valve
abnormalities in a patient comprising: (1) a non-invasive pressure
inducing means for inducing a pressure to a body part of a patient;
(2) a data receiving means for receiving a stream of pulsation
signal data from the patient relating to the pressure response of
pulsed fluid flowing through the cardiovascular system of the
patient; (3) a data processing means for processing the stream of
pulsation signal data to create a time dependant array of pulse
wave forms; and (4) means for aiding in the identification of wave
form characteristics that denote the presence of aortic valve
abnormalities.
19. The device of claim 18 further comprising graphic display means
for displaying the time dependant array of pulse wave forms.
20. The device of claim 18 wherein each of the pulse wave forms of
the time dependant array of pulse wave forms includes a peak, and
the means for aiding in the identification of wave form
characteristics includes means for aiding in the comparison of the
height of a series of adjacent wave form peaks.
21. The device of claim 20 wherein the means for aiding in the
comparison includes means for aiding in the comparison of the
height of at least four adjacent peaks, P.sub.1, P.sub.2, P.sub.3
and P.sub.4, having heights of H.sub.1, H.sub.2, H.sub.3 and
H.sub.4, respectively.
22. The device of claim 21 further comprising means for detecting
the presence of aortic valve abnormalities if at least one of:
H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3 >H.sub.4 ;
and H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and H.sub.3
<H.sub.4 occurs.
23. The device of claim 18 wherein the time dependant array of
pulse wave forms comprises a series of at least four adjacent pulse
wave forms including a first wave form having a peak P.sub.1, and a
height H.sub.1 ; a second pulse wave form having a peak P.sub.2 and
a height H.sub.2 ; a third pulse wave form having a peak P.sub.3
and a height H.sub.3 ; and a fourth pulse wave form having a peak
P.sub.4 and a height H.sub.4 ; further comprising means for
detecting the presence of aortic valve abnormalities if at least
one of: H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3
>H.sub.4 ; and H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and
H.sub.3 <H.sub.4 occurs.
24. The device of claim 18 further comprising means for graphically
displaying the time dependant array of pulse wave forms, wherein
the time dependant array of pulse wave forms displayed by the
graphic display means includes a series of pulse wave forms each
having a peak, and the graphic display means includes means for
displaying an envelope line that extends between the peaks of
adjacent wave forms, and the means for aiding in the identification
of wave form characteristics includes means for identifying the
slope of the envelope line to determine whether it denotes the
presence of aortic valve abnormalities.
25. The device of claim 24 wherein the means for identifying the
slope of the envelope line comprises means for determining whether
the envelope line has an undulating slope, thereby suggesting the
presence of aortic valve abnormalities.
26. A device for identifying the existence of aortic valve
abnormalities, comprising: (1) a non-invasive pressure inducing
means for inducing a pressure to a body part of a patient; (2) a
data receiving means for receiving a stream of pulsation signal
data from the patient relating to the pressure response of pulsed
fluid flowing through a cardiovascular system of the patient; (3) a
data processing means for processing the stream of pulsation signal
data to create an array of time dependant wave form data; (4) means
for converting the array of time dependant wave form data to an
array of frequency dependant wave form data; and (5) means for
aiding in the identification of characteristics of the frequency
dependant wave form data that denote the presence of aortic valve
abnormalities.
27. The device of claim 26 wherein the means of converting the time
dependant wave form data comprises a program means using a Fourier
transformation to convert the time dependant wave form data to
frequency dependant wave form data.
28. The device of claim 26 wherein the means for aiding in the
identification of the characteristics of the frequency dependant
wave form data includes means for aiding in the identification of a
first series of harmonically occurring flow signals corresponding
to a flow of fluid forwardly through the aortic valve, and in the
detection of the presence or absence of a second series of
harmonically occurring flow signals corresponding to aortic
regurgitation.
29. The device of claim 28 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has an amplitude
A.sub.1, and each of the flow signals of the second series has an
amplitude A.sub.2 and further comprising means for comparing the
amplitude A.sub.2 of a flow signal of the second series to the
amplitude A.sub.1 of a flow signal of the first series to obtain a
semi-quantitative analysis of the aortic regurgitation.
30. The device of claim 29 wherein the means for comparing the
amplitudes comprises means for determining a ratio A.sub.2 /A.sub.1
of the amplitudes of corresponding flow signals of the second and
first series to approximate the ratio of aortic regurgitation flow
to forward fluid flow through the aortic valve.
31. The device of claim 28 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has a density D.sub.1
each of the flow signals of the second series has a density,
D.sub.2 and further comprising means for comparing the density
D.sub.2 of the flow signal of the second series to the density
D.sub.1 of the flow signal of the first series to obtain a
semi-quantitative value of the aortic regurgitation.
32. The device of claim 31 wherein the means for comparing the
densities comprises means for determining the ratio D.sub.2
/D.sub.1 of corresponding flow signals of the second and first
series to approximate the ratio of aortic regurgitation flow, to
the flow of fluid forward through the aortic valve..Iadd.
33. A method for identifying the existence of aortic valve
abnormalities in a patient wherein the patient employs a
non-invasive pressure inducer for inducing a pressure on a body
part of the patient by applying pressure to the body part, and
generating a stream of pulsation signal data relating to the
pressure response of pulsed fluid flowing through the
cardiovascular system of the patient, the method comprising the
steps of: (1) providing a data receiver; (2) using the data
receiver to receive the stream of pulsation signal data; (3)
providing a data processor; (4) using the data processor for
processing the stream of pulsation signal data to create an array
of wave forms; and (5) identifying wave form characteristics that
denote the presence of aortic valve
abnormalities..Iaddend..Iadd.
34. The method of claim 33 wherein the step of using the data
processor comprises the step of using the data processor to create
a time dependant array of wave forms..Iaddend..Iadd.
35. The method of claim 34 wherein each of the wave forms of the
time dependant array of wave forms includes a peak, and the step of
identifying wave form characteristics includes the step of
comparing the height of a series of adjacent wave form
peaks..Iaddend..Iadd.
36. The method of claim 35 wherein the step of comparing the height
of a series of adjacent wave form peaks includes the step of
comparing the height of at least four adjacent peaks, P.sub.1,
P.sub.2, P.sub.3 and P.sub.4, having heights of H.sub.1, H.sub.2,
H.sub.3 and H.sub.4, respectively..Iaddend..Iadd.
37. The method of claim 36 further comprising the step of detecting
the presence of aortic valve abnormalities if at least one of (1):
H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3 >H.sub.4 ;
and (2): H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and H.sub.3
<H.sub.4 occurs..Iaddend..Iadd.
38. The method of claim 33 wherein the array of wave forms
comprises a series of at least four adjacent wave forms including a
first wave form having a peak P.sub.1, and a height H.sub.1 ; a
second wave form having a peak P.sub.2 and a height H.sub.2 ; a
third wave form having a peak P.sub.3 and a height H.sub.3 ; and a
fourth wave form having a peak P.sub.4 and a height H.sub.4 ;
further comprising the step of detecting the presence of aortic
valve abnormalities if at least one of: (1) H.sub.1 >H.sub.2,
H.sub.2 <H.sub.3, and H.sub.3 >H.sub.4 ; and (2) H.sub.1
<H.sub.2, H.sub.2 >H.sub.3 and H.sub.3 <H.sub.4
occurs..Iaddend..Iadd.
39. The method of claim 33 further comprising the step of
graphically displaying the array of wave forms..Iaddend..Iadd.
40. The method of claim 39 wherein (1) the step of using the data
processor comprises the step of using the data processor to create
a time dependant array of wave forms including a series of
waveforms each having a peak, (2) the step of graphically
displaying the array of waveforms comprises the step of graphically
displaying the time dependant array of wave forms includes the
series of wave forms each having a peak, (4) the step of
graphically displaying the time dependant array includes the step
of displaying an envelope line that extends between the peaks of
adjacent wave forms, and (5) the step of identifying wave form
characteristics includes the step of identifying the slope of the
envelope line to determine whether it denotes the presence of
aortic valve abnormalities..Iaddend..Iadd.
41. A method for identifying the existence of aortic valve
abnormalities in a patient wherein the patient employs a
non-invasive pressure inducer for inducing a pressure on a body
part of the patient, and who exerts a pressure on the body part,
thereby generating a stream of pulsation signal data relating to
the pressure response of pulsed pressure flowing through the
cardiovascular system of the patient, the method comprising the
steps of: (1) providing a data receiver; (2) using the data
receiver to receive the stream of pulsation signal data (3)
providing a data processor; (4) processing the stream of pulsation
signal data to create an array of time dependant wave form data;
(5) converting the array of time dependant wave form data to an
array of frequency dependant wave form data; and (6) identifying
characteristics of the frequency dependant wave form data that
denote the presence of aortic valve
abnormalities..Iaddend..Iadd.
42. The method of claim 41 wherein the steps of converting the time
dependant wave form data comprises the step of using a Fourier
transformation to convert the time dependant wave form data to
frequency dependant wave form data..Iaddend..Iadd.
43. The method of claim 41 wherein the step of identifying the
characteristics of the frequency dependant wave form data includes
the step of identifying a first series of harmonically occurring
flow signals corresponding to a flow of fluid forwardly through the
aortic valve, and detecting the presence or absence of a second
series of harmonically occurring flow signals corresponding to
aortic regurgitation..Iaddend..Iadd.
44. The method of claim 43 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has an amplitude
A.sub.1, and each of the flow signals of the second series has an
amplitude A.sub.2 and further comprising the step of comparing the
amplitude A.sub.2 of a flow signal of the second series to the
amplitude A.sub.1 of a flow signal of the first series to obtain a
semi-quantitative analysis of the aortic
regurgitation..Iaddend..Iadd.
45. The method of claim 44 wherein the step of comparing the
amplitudes comprises the step of determining a ratio A.sub.2
/A.sub.1 of the amplitudes of corresponding flow signals of the
second and first series to approximate the ratio of aortic
regurgitation flow to forward fluid flow through the aortic
valve..Iaddend..Iadd.
46. The method of claim 41 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has a density, D.sub.1
each of the flow signals of the second series has a density,
D.sub.2 and further comprising the step of comparing the density
D.sub.2 of the flow signal of the second series to the density
D.sub.1 of the flow signal of the first series to obtain a
semi-quantitative value of the aortic
regurgitation..Iaddend..Iadd.
47. The method of claim 46 wherein the step of comparing the
densities comprises the step of determining the ratio D.sub.2
/D.sub.1 of corresponding flow signals of the second and first
series to approximate the ratio of aortic regurgitation flow, to
the flow of fluid forward through the aortic
valve..Iaddend..Iadd.
48. The method of claim 43 further comprising the step of
evaluating the frequency shift between the flow signals of the
first series and the flow signals of the second
series..Iaddend..Iadd.
49. The method of claim 48 wherein the step of evaluating the
frequency shift comprises the step of evaluating the frequency
shift between the flow signals of the first series and the flow
signals of the second series to determine at least one of the
nature, type and characteristics of the aortic regurgitation of the
patient..Iaddend..Iadd.
50. A device for identifying the existence of aortic valve
abnormalities in a patient wherein a non-invasive pressure inducer
has been employed for applying a pressure to a body part and for
generating a stream of pulsation signal data relating to the
pressure response of pulsed fluid flowing through the
cardiovascular system of the patient, the device comprising: (1) a
data receiver for receiving the stream of pulsation signal data;
and (2) a data processor for processing the stream of pulsation
signal data to create a time dependant array of wave forms, the
data processor including a program for aiding in the identification
of wave form characteristics that denote the presence of aortic
valve abnormalities..Iaddend..Iadd.
51. The device of claim 50 further comprising a graphic display for
displaying the time dependant array of wave
forms..Iaddend..Iadd.
52. The device of claim 50 wherein each of the wave forms of the
time dependant array of wave forms includes a peak, and the program
for aiding in the identification of wave form characteristics
includes a program for aiding in the comparison of the height of a
series of adjacent wave form peaks..Iaddend..Iadd.
53. The device of claim 52 wherein the program for aiding in the
comparison includes a program for aiding in the comparison of the
height of at least four adjacent peaks, P.sub.1, P.sub.2, P.sub.3
and P.sub.4, having heights of H.sub.1, H.sub.2, H.sub.3 and
H.sub.4, respectively..Iaddend..Iadd.
54. The device of claim 53 wherein the program includes programming
for detecting the presence of aortic valve abnormalities if at
least one of: H.sub.1 >H.sub.2, H.sub.2 <H.sub.3, and H.sub.3
>H.sub.4 ; and H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and
H.sub.3 <H.sub.4 occurs..Iaddend..Iadd.
55. The device of claim 50 wherein the time dependant array of wave
forms comprises a series of at least four adjacent wave forms
including a first wave form having a peak P.sub.1, and a height
H.sub.1 ; a second wave form having a peak P.sub.2 and a height
H.sub.2 ; a third wave form having a peak P.sub.3 and a height
H.sub.3 ; and a fourth wave form having a peak P.sub.4 and a height
H.sub.4 wherein the program includes a program for detecting the
presence of aortic valve abnormalities if at least one of: H.sub.1
>H.sub.2, H.sub.2 <H.sub.3, and H.sub.3 >H.sub.4 ; and
H.sub.1 <H.sub.2, H.sub.2 >H.sub.3 and H.sub.3 <H.sub.4
occurs..Iaddend..Iadd.
56. The device of claim 50 further comprising a graphic display for
displaying the time dependant array of wave forms, wherein the time
dependant array of wave forms displayed by the graphic display
includes a series of wave forms each having a peak, and the graphic
display is capable of displaying an envelope line that extends
between the peaks of adjacent wave forms, and the program for
aiding in the identification of wave form characteristics includes
a program for identifying the slope of the envelope line to
determine whether it denotes the presence of aortic valve
abnormalities..Iaddend..Iadd.
57. The device of claim 56 wherein the program for identifying the
slope of the envelope line is capable of determining whether the
envelope line has an undulating slope, thereby suggesting the
presence of aortic valve abnormalities..Iaddend..Iadd.
58. A device for identifying the existence of aortic valve
abnormalities in a patient wherein a non-invasive pressure inducer
has been employed for applying a pressure to a body part of the
patient, and for generating a stream of pulsation signal data
relating to the pressure response of pulsed fluid flowing through
the cardiovascular system of the patient, the device comprising:
(1) a data receiver for receiving the stream of pulsation signal
data; (2) a data processor for processing the stream of pulsation
signal data to create an array of time dependant wave form data;
(3) a conversion program for converting the array of time dependant
wave form data to an array of frequency dependant wave form data;
and (4) a program for aiding in the identification of
characteristics of the frequency dependant wave form data that
denote the presence of aortic valve
abnormalities..Iaddend..Iadd.
59. The device of claim 58 wherein the conversion program comprises
a conversion program that uses a Fourier transformation to convert
the time dependant wave form data to frequency dependant wave form
data..Iaddend..Iadd.
60. The device of claim 58 wherein the program for aiding the
identification of the characteristics of the frequency dependant
wave form data includes a program for aiding in the identification
of a first series of harmonically occurring flow signals
corresponding to a flow of fluid forwardly through the aortic
valve, and in the detection of the presence or absence of a second
series of harmonically occurring flow signals corresponding to
aortic regurgitation..Iaddend..Iadd.
61. The device of claim 60 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has an amplitude
A.sub.1, and each of the flow signals of the second series has an
amplitude A.sub.2 and further comprising a comparison program for
comparing the amplitude A.sub.2 of a flow signal of the second
series to the amplitude A.sub.1 of a flow signal of the first
series to obtain a semi-quantitative analysis of the aortic
regurgitation..Iaddend..Iadd.
62. The device of claim 61 wherein the comparison program is
capable of determining a ratio A.sub.2 /A.sub.1 of the amplitudes
of corresponding flow signals of the second and first series to
approximate the ratio of aortic regurgitation flow to forward fluid
flow through the aortic valve..Iaddend..Iadd.
63. The device of claim 60 wherein the flow signals of the first
series each have a corresponding flow signal of the second series,
each of the flow signals of the first series has a density, D.sub.1
each of the flow signals of the second series has a density,
D.sub.2 and further comprising a comparison program for comparing
the density D.sub.2 of the flow signal of the second series to the
density D.sub.1 of the flow signal of the first series to obtain a
semi-quantitative value of the aortic
regurgitation..Iaddend..Iadd.
64. The device of claim 63 wherein the comparison program for
comparing the densities is capable of determining the ratio D.sub.2
/D.sub.1 of corresponding flow signals of the second and first
series to approximate the ratio of aortic regurgitation flow, to
the flow of fluid forward through the aortic valve..Iaddend.
Description
I. TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and apparatus for
determining the cardiovascular condition of a patient, and more
particularly to a method and apparatus for monitoring aortic valve
abnormalities such as aortic regurgitation.
II. BACKGROUND OF THE INVENTION
A. The Pathology of Aortic Regurgitation.
Heart valve abnormalities are a major component of cardiovascular
disease. Aortic Regurgitation (AR), also known as Aortic
Insufficiency (AI), is probably the most common valvular problem.
Each year thousands of patients experience cardiovascular function
problems as a result of aortic regurgitation. Eventually many of
these cases lead to the need for surgical intervention such as
aortic valve replacement. Therefore, the detection and evaluation
of aortic regurgitation is extremely important in those subjects
with suspected cardiovascular disease. The development of a simple,
inexpensive technique by which to screen individuals for aortic
regurgitation is extremely important in those subjects with
suspected cardiovascular disease. The development of a simple,
inexpensive technique and apparatus with which one can screen
individuals for aortic regurgitation represents an advance in
medical instrumentation.
Aortic regurgitation may be caused by a variety of diseases or
acute trauma. In the case of disease, the process may act directly
on the aortic valve leaflet or the wall of the aortic root.
Approximately two-thirds of severe aortic regurgitation cases which
result in aortic valve replacement are caused by leaflet
abnormalities. As used in this application, the term "aortic valve
abnormalities" is broad enough to encompass all of the various
conditions which result in aortic regurgitation.
Rheumatic fever is a common disease mechanism of many valve leaflet
abnormalities. The fever causes the cusps to become infiltrated
with fibrous tissues and retract, a process that prevents the cusps
from closing during diastole. This usually results in AR in the
left ventricle through the center of the valve. Diseases such as
infective endocarditis may cause aortic regurgitation through a
similar mechanism.
In contrast, diseases such as Syphilis, Ankylosing Spondylitis,
Rheumatoid Arthritis, and Marfan Syndrome may produce aortic
regurgitation by causing marked dilation of the ascending aorta. In
each of these diseases, the aortic annulus may become greatly
dilated, the aortic leaflets may separate, and AR may ensue. In
addition, the dilation of the aortic root may have a secondary
effect on the aortic valve, since it may cause tension and bowing
of the cusps which may thicken, retract, and become too short to
close the aortic orifice.
Acute trauma may produce aortic regurgitation as a result of
mechanical damage. For example, a tear in the ascending aorta may
cause loss of valve leaflet support and therefore lead to the
initiation of regurgitation.
Regardless of the etiology, Aortic Regurgitation usually produces
dilation and hypertrophy of the left ventricle as a result of the
chronic regurgitant flow. It may also produce dilation of the
mitral valve ring and the left atrium. These changes represent
cardiovascular system adaptation as a result of chronic or
gradually increasing aortic regurgitation. The systemic response
permits the ventricle to perform as an effective high compliance
pump. As a result, patients with severe chronic AR have the largest
end-diastolic volumes of those with any form of heart disease.
High end-diastolic and stroke volumes assist in maintaining proper
cardiovascular function. As the left ventricle dilates, ventricular
function deteriorates due to the inability to efficiently move
blood out of the heart. Rising end-diastolic volumes eventually
cannot compensate for the regurgitant volume, and the ejection
fraction and forward stoke volume decline. In order to restore
forward stroke volume and ventricular function, aortic valve
replacement usually must be performed.
Unfortunately, the cardiovascular system cannot adapt quickly to
acute aortic regurgitation. As a result, the back flow of blood
through the damaged valve will fill the ventricle. A ventricle of
normal size cannot accommodate the combined large regurgitate
volume and atrium inflow. Since total stroke volume cannot rise due
to structural constraints, forward stroke volume will decline. In
response, left ventricle diastolic pressure may rise quickly, and
cardiac function may drop drastically. Cardiovascular complications
may ensue quickly threatening the life of the patient.
B. Prior Art Methods for Detecting and Evaluating Aortic
Regurgitation.
The state-of-the-art methods for detecting aortic regurgitation and
either evaluating the severity of disease or quantifying the amount
of regurgitate volume include echocardiography, invasive
catheterization, and magnetic resonance imaging (MRI).
A variety of echocardiography techniques can be utilized to
evaluate aortic regurgitation. Although M-mode or two-dimensional
ultrasound may be quite useful to detect aortic regurgitation or
structural changes, the addition of Doppler may be quite useful to
measure the outflow velocity from the aortic valve. When combined
with measurements of valve diameter, the flow can be calculated.
Color flow Doppler represents a drastic improvement in echo imaging
due to the ability to approximate the regurgitate volume.
Additionally, continuous wave Doppler may also be a useful
technique to evaluate the severity of the disease in which the
deceleration slope of the ventricular pressure gradient is
evaluated. This is accomplished using the Bernoulli equation which
relates velocity changes to a pressure gradient.
Invasive techniques may also be used to evaluate aortic
regurgitation. Many of these invasive techniques utilize a scale
from 1 to 4+ to evaluate the severity of the aortic regurgitation.
This is accomplished using angiography techniques to review the
degree of regurgitate back flow through the aortic valve.
Recently, however, major advances have been made using MRI to
evaluate aortic regurgitation. MRI can be used to simultaneously
evaluate the severity of both aortic regurgitation and left
ventricle dysfunction. Past MRI techniques utilized multiple
tomographic planes which made the process time consuming and
difficult to analyze. In addition, the techniques focused simply on
the size of the regurgitate flow jet, which has a poor correlation
to regurgitate volume. However, recently developed techniques
utilize a rapid single-plane cine MRI technique which can be
completed in less than 10 minutes. The new technique incorporates a
new grading system which is based on the presence, size, and
persistence of not only the regurgitate jet, but also the zone of
proximal signal loss.
Unfortunately, invasive catheter procedures, echocardiography, and
MRI are associated with several problems which may limit routine
clinical utilization. Invasive catheterization, for example, is
extremely expensive due to the cost of the physician, support
personnel, and hospital overhead. These procedures may also be
associated with considerable patient risk due to their invasive
nature. Additionally, although highly accurate, these procedures
are quite time-consuming to perform and usually require an
overnight hospital stay. Therefore, few individuals undergo
evaluation of aortic regurgitation using invasive techniques.
Non-invasive echocardiography procedures may reduce costs since
they can be performed on an out-patient basis, however, they still
require the cost of highly skilled personnel. Echocardiography is
usually performed by a highly skilled technician and study results
are usually evaluated by a specialized physician (cardiologist).
Reproducibility may be of concern, however, since results may vary
depending on the placement of the non-invasive transducer and the
ability of the operator. In addition, the use of two-dimensional
imaging may potentially underestimate or overestimate the size of
physiological structures since the third dimension in space cannot
be evaluated. Potential patient risk may be minimized due to the
non-invasive nature of the procedure. However, the time
requirements may still potentially limit utilization in some
patients.
Although the development of new MRI techniques may represent an
advance in the clinical assessment of aortic regurgitation, the
expense of such procedures is of great concern. MRI equipment is
extremely expensive, and patient access is quite limited.
Importantly, although no biological after-effects have been seen
from MRI, the body is exposed to low energy radiation which could
be potentially hazardous. Further, the operation of an MRI requires
highly skilled operators including qualified technicians and a
specialized physician (radiologist). Although new methods may
reduce procedure time, patient preparation time is still considered
very significant.
Room for improvement exists over the known methods for determining
aortic regurgitation. In particular, improvement can be achieved by
providing a reliable method for determining the existence of aortic
regurgitation, and a method for enabling the physician to perform a
semi-quantitative analysis of the volume of aortic regurgitation,
which does not require an invasive procedure. Further, the state of
the known art would be improved by the existence of a method for
determining and quantifying aortic regurgitation that can be
performed easily by relatively low cost personnel, especially if
the method could be performed on the patient without the need for
expensive equipment.
It is therefore one object of the present invention to provide a
method and apparatus for determining the existence of aortic valve
abnormalities of the type that cause aortic regurgitation. It is
also an object of the present invention to provide a method and
apparatus that can enable a practitioner to determine the existence
of aortic regurgitation, and to perform a semi-quantitative
analysis of the relative volume of aortic regurgitation.
It is a further object of the present invention to provide a method
and apparatus for determining aortic regurgitation which does not
require expensive equipment or invasive procedures.
III. SUMMARY OF THE INVENTION
In accordance with the present invention, a method is provided for
identifying the existence of aortic valve abnormalities in a
patient. The method comprises the steps of providing a pressure
inducing means for inducing a pressure to a body part of a patient.
A data receiving means is provided, which is used for receiving a
stream of pulsation signal data from the patient relating to
pressure response of pulsed fluid flowing through the
cardiovascular system of the patient. A data processing means
processes the stream of data to create an array of pulse wave
forms. Wave form characteristics are then identified that denote
the presence of aortic valve abnormalities.
Preferably, the data processing means is used to create a time
dependant array of pulse wave forms which is graphically displayed
by a graphic display means, such as a computer monitor or a paper
printout.
Also, each of the pulse wave forms of the time dependant array of
pulse wave forms can include a peak. Wave form characteristics that
indicate the presence of aortic valve abnormalities can be
identified by comparing the heights of a series of adjacent wave
form peaks. The graphic display of the time dependant array can
include an envelope line that extends between the peaks of adjacent
wave forms. The slope of the envelope line can be used to identify
the existence of aortic valve abnormalities. If the envelope line
has an undulating slope, the presence of aortic valve abnormalities
is suggested.
In an alternate embodiment, the time dependent wave form data can
be converted to frequency dependant wave form data through the use
of a Fourier transformation. Characteristics of the frequency
dependant wave form data can be identified which suggest the
presence of aortic regurgitation. These characteristics are
identified by first identifying a first series of harmonically
occurring flow signals that correspond to a "main" flow of fluid
forwardly through the aortic valve, and then detecting the presence
or absence of a second series of harmonically occurring
"regurgitation" flow signals corresponding to the aortic
regurgitation. The first and second series of signals each have an
amplitude. By comparing the amplitude A.sub.2 of a flow signal of
the second series to the amplitude A.sub.1 of a flow signal of the
first series, a semi-quantitative analysis of the aortic
regurgitation can be performed. Additionally, a semi-quantitative
relative value for the aortic regurgitation can be obtained by
comparing the density D.sub.2 of the flow signal of the second
series to the density D.sub.1 of the flow signal of the first
series.
In accordance with another aspect of the present invention, a
device is provided for identifying the existence of aortic valve
abnormalities in a patient which comprises a pressure inducing
means for inducing a pressure to a body part of a patient, a data
receiving means for receiving a stream of pulsation signal data
from the patient relating to the pressure response of pulsed fluid
flowing through the cardiovascular system of the patient. A data
processing means is provided for processing the stream of data to
create a time dependant array of pulse wave forms. Means are
provided for aiding in the identification of wave form
characteristics that denote the presence of aortic valve
abnormalities.
One feature of the present invention is that it enables the user to
identify characteristics that denote the presence of aortic valve
abnormalities (and hence, aortic regurgitation) through the use of
a non-invasive pressure inducing means. This feature has the
advantage of enabling the physician to determine and diagnose a
condition through the use of a procedure which is minimally
invasive, and which can be performed at low cost. This feature has
the further advantage of enabling testing to be conducted for
aortic valve abnormalities for a wide number of people, thus making
such a test affordable enough to be employed as a "screening"
test.
Another feature of the present invention is that data is provided
which includes a first series of signals indicative of the flow of
fluid forwardly through the aortic valve, and a second series of
signals indicative of aortic valve regurgitation. By comparing
these two signals, a semi-quantitative analysis of the volume of
aortic regurgitation can be obtained. This feature has the
advantage of enabling the user to obtain some quantitative data
about the extent of aortic regurgitation, which is indicative of
the severity of the patient's problems.
Another advantage of this invention is that the procedure can be
performed during routine blood pressure measurement. As a result,
the procedure should take no more than a few minutes or so, with an
automated computer having fast Fourier transformation (FFT) and
Power Spectrum Display (PSD) program. Due to the use of a
non-invasive cuff sphygmomanometer, the procedure should be useable
by personnel having no special training for operation. Importantly,
patient risk from the procedure is almost non-existent, being no
greater than the risk associated with routine blood pressure
measurement.
Another advantage is that personnel training time is minimized as
similar devices, using oscillometric technology, are used routinely
every day in hospitals and physician offices around the world.
Additionally, the cost of performing the procedure should be low
compared to the other state-of-the-art technologies discussed
previously. Also, the use of computer automation and analysis
techniques should enable the user to achieve accurate evaluations
of aortic valve irregularities.
These and other features and advantages of the present invention
will become apparent to those skilled in art upon a review of the
detailed description of the preferred embodiment of the present
invention, which presently represents the best mode perceived by
the inventors of practicing this invention.
IV. BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b represent displays of pulsation signal data taken
from two normal patients.
FIGS. 2a and 2b represent displays of pulsation signal data taken
from two mild, level-1, aortic regurgitation patients.
FIGS. 3a and 3b represent displays of pulsation signal data taken
from two severe, level-3, aortic regurgitation patients.
FIGS. 4a and 4b represent displays of frequency dependant, Fourier
transformed (FFT) power spectra data of the two normal patients,
whose time dependant data is shown in FIGS. 1a and 1b
respectively.
FIGS. 5a and 5b represent displays of frequency dependant, Fourier
transformed (FFT) power spectra data of the two mild AR patients,
whose time dependant data is shown in FIGS. 2a and 2b
respectively.
FIGS. 6a and 6b represent displays of frequency dependant, Fourier
transformed (FFT) power spectra data of the two severe AR patients,
whose time dependant data is shown in FIGS. 3a and 3b
respectively.
FIG. 7 represents a diagrammatic representation of the components
of the present invention.
V. DETAILED DESCRIPTION
This invention uses the same apparatus and data obtaining means as
is disclosed in Chio U.S. Pat. Nos. 4,880,013 and 5,162,991, the
disclosure of which is incorporated herein by reference. The
products discussed in the Chio patents are commercially available
as the Dynapulse.RTM. blood pressure monitor from Pulse Metric.RTM.
Inc. of San Diego, Calif. 92121. To briefly restate that which is
disclosed in the earlier Chio references, your attention is now
directed to FIG. 7.
The apparatus of the present invention includes a non-invasive
pressure inducing means such as a cuff 10 for exerting a pressure
on a body part, such as an arm. Although a wide variety of pressure
inducing means can be used, the pressure inducing means preferably
comprises an inflatable cuff 10 which can be wrapped around the
limb of a patient. Typically, such an inflatable cuff 10 includes a
pump means (either manually actuated or electronically actuated)
which pumps air into the interior of the cuff to exert pressure on
the body part. An example of such a cuff 10 is the cuff supplied
with the DYNAPULSE blood pressure monitor manufactured by Pulse
Metric, Inc. of San Diego, Calif., the assignee of the present
invention. Most other available blood pressure cuffs work in a
similar manner.
A transducer means 16 is provided for picking up the total pressure
induced signals, including the background pressure signals and the
small oscillation (pulsation) signals. The transducer means 16
converts these pressure signals that are picked up into electrical
signals. Typically, the background pressure signals are picked up
as DC signals, and the pulsation signals are picked up as AC
signals. These signals are picked up over a period of time, and
thus, give rise to a time dependant array of pulsation signals.
The pressure transducer 16 primarily comprises a solid state
pressure sensor or similar device that is capable of picking up
pressure signals and converting these pressure signals into an
analog electrical signal for transmission from the transducer means
16. An example of a pressure transducer that will work well with
the present invention is the pressure transducer found within the
DYNAPULSE device described above. Preferably, the pressure
transducer 16 has a linear response rate, or has a known
correlation between the input pressure received by the transducer
16 and the output electrical signal (e.g. voltage sent out by the
transducer.) The transducer 16 generates a voltage signal which
comprises a generally continuous overall pressure data stream 20.
The overall pressure data stream 20 is sent in a generally
continuous manner, over time, to the analog-to-digital converter
26. The analog-to-digital converter 26 converts the analog
information provided by the transducer 16 into digital
information.
A digitized pressure data stream 30 is fed from the
analog-to-digital converter 26 to a data processing means such as a
computer 36. As with data stream 20, the digitized data stream 30
represents an essentially continuous stream of data taken over a
period of time. The computer data processing means should
preferably be an IBM compatible computer. The speed and
capabilities of the computer necessary to perform the tasks of the
present invention are dictated largely by the complexity of the
software. However, all the tasks described above can be
accomplished with a computer as limited in capabilities as a 1988
or 1989 vintage IBM XT or AT computer using an 8086 or 80286 Intel
processing chip, and of course can be accomplished with any of the
more recent, more powerful IBM compatibles (e.g. 80586 or 80680)
devices.
As will be appreciated, the heart of the data processing means
(computer 36) is the software that directs the computer on how to
process the data that is fed into it through the digitized data
stream 30. The exact nature of the software will be described in
more detail below.
The computer 36, through its software, processes the data to
translate the data into a usable information stream. This useful
information stream can be for example (1) a stream 40 that is
forwarded to a graphic display, such as a computer monitor 42; (2)
a printer-readable information stream 44 that is fed to a printer
46; and/or (3) a stream 48 fed to a data storage means, such as a
hard drive 50, a floppy disc, or compact disc.
An appropriate pressure transducer 16 and analog-to-digital
converter 26 are provided with the DYNAPULSE blood pressure
monitoring system, which also includes a pressure inducing cuff 10.
The data storage device 50, monitor 42, printer 46 and computer 36
are of the type that are available from any one of several computer
manufacturers (such as Gateway and Compaq); printer manufacturers
(e.g. Hewlett Packard and Canon); and monitor manufacturers (e.g.
Samsung, and NEC).
The first step in the process of the present invention is to gather
data from the patient of interest. The manner in which the data is
gathered from the patient is similar to the manner discussed in the
above referenced Chio '013 and '991 patents. The cuff 10 is affixed
to the patient and operated in accordance with its usual operating
procedures. Pressure is induced by the pressure inducing means on
the patient's body part which is above the normal systolic blood
pressure of the patient. This supra systolic blood pressure that is
induced on a patient is typically between 140 and 250 mmHg,
depending upon the normal systolic blood pressure of the patient.
Over a period of time, typically lasting between about 20 and 60
seconds, the pressure that is induced by the pressure inducing
means is gradually reduced, in a manner very much identical to the
manner in which the induced pressure is reduced during a blood
pressure measurement. Preferably, the cuff pressure is decreased in
a smooth manner during the test period, a smooth decrease in
pressure facilitates the construction and interpretation of the
graphic displays produced by the instant invention.
When the test begins, the pressure induced by the pressure inducing
means 10 is at a supra systolic pressure. As the test progresses,
the pressure continues to decrease past the point wherein the
pressure induced by the pressure inducing means 10 equals the
patient's systolic pressure. The pressure induced by the pressure
inducing means 10 continues to decrease past the point of the
patient's mean arterial pressure (MAP), and past the point where
the pressure induced by the pressure inducing means 10 equals the
patient's diastolic pressure. The pressure then continues to
decrease, so that data is obtained at a subdiastolic pressure,
which is a pressure that is below the patient's measured diastolic
pressure. It has been found by the applicant that the best results
are achieved from data obtained at either supra systolic pressure,
or subdiastolic pressures.
The pressure transducer 16 comprises a data receiving means for
receiving a stream of pulsation signal data from the patient that
relates to the pressure response of a pulsed fluid, such as blood,
that is flowing through the cardiovascular system of the patient.
This pulsation signal data is then processed by the
analog-to-digital converter 26 and the computer 36, both of which
perform some data processing functions.
The primary data processor (the computer 36) is asked to perform
three primary functions within the present invention. As such,
three different items of software are required to perform these
functions, although it will be appreciated, that all three software
components can be packaged together within a single software
"package".
The first function performed by the data processor is to collect
the data that is being fed to it through the overall pressure data
stream 30, and to perform the necessary processing of the data so
that it provides useful information, when in its time dependant
display mode. This program is the "Dynapulse.RTM." program that is
available from Pulse Metric, Inc., of San Diego, Calif., U.S.A. A
second software function performed by the computer and its software
is to convert the time dependant array of pulse wave forms into an
array of frequency dependant wave forms. This is accomplished
through a Fourier transformation program. Fourier transformation
programs are available, and the fast Fourier transformation (FFT)
and Power Spectrum Display (PSD) programs that will function well
with the present invention can be obtained from, William H. Press
et al., Numerical Recipes in C, 2nd ed., Cambridge University
Press, 1992. For displaying the various information in a graphic
display, the applicants have found that the Excel.RTM. program sold
by the Microsoft.RTM. Corporation of Seattle, Wash., U.S.A.
performs adequately for the tasks demanded by the present
invention.
Your attention is now directed to FIGS. 1a and 1b, which comprise
data taken from two patients (here known as patient 1a and 1b) who
have generally normal aortic valves, and do not experience any
abnormal aortic regurgitation. The data shown in FIG. 1a is data
that has been processed by the data processing means to create the
array of time dependant pulse wave form data shown in FIGS. 1a and
1b. It will be noted that the pulse signals occurred over
approximately a 27 second time period during which the pressure
inducing means varied the pressure induced on the patient, from a
high of about 130 mmHg at time 00, to less than 40 mmHg, at time 27
seconds. It will be noted that the data comprises a series of
pulsation peaks such as peak 60, and nadir points, such as nadir
point 61. In the example shown in FIG. 1a, the particular patient
had a systolic pressure of 106 mmHg, as indicated by arrow 62, a
diastolic pressure of 43 mmHg, as indicated by arrow 64, and mean
arterial pressure of 62 mmHg, as indicated by arrow 66.
Your attention is now directed to the peak points of the various
wave forms. In this regard, it will be noted that an envelope line
70 is drawn between the adjacent peaks of the pulse wave forms. The
overall configuration of the envelope line 70 is generally
bell-shaped, rising from a low point that begins as supra systolic
pressures, to an apex of the bell, at point 74, which is generally
close to the mean arterial pressure point 66, and then descending
gradually to another relatively lower end point that occurs at
subdiastolic pressures. This reflects that the height of the peaks,
generally increases as one moves in the area from supra systolic
pressures to the mean arterial pressure, and then generally
decreases in the area from the mean arterial pressure to
subdiastolic pressures. Importantly, it should be noted that the
envelope line 70, although not perfectly bell-shaped, cannot be
characterized as undulating or wave-like.
Turning now to the individual peaks, if one were to choose four
adjacent peaks from four adjacent wave forms, such as, first peak
60, second adjacent peak 76, third adjacent peak 78 and fourth
adjacent peak 80, one would note that the height of the first peak
60 is less than the height of the second peak 76, and that the
height of the second peak 76 is less than the height of the third
peak 78. The height of the fourth peak 80 is approximately equal to
the height of the third peak 78, or possibly slightly lower.
Importantly, the general trend of the four peaks is one of
generally increasing height and is not one of undulation. This is
what you would expect as the envelope line 70 does not itself have
an undulating slope.
Turning now to FIG. 1b, you will notice that similar results would
be obtained if the peak heights were compared from four adjacent
peak points of four adjacent pulse wave forms. Further, the slope
of the envelope line 82 is generally bell-shaped, and not
undulating. As discussed above, FIGS. 1a and 1b represent data
obtained from "normal" patients who did not suffer from any
substantial aortic regurgitation.
Turning now to FIGS. 2a and 2b, data is shown from patients who
have mild aortic regurgitation. It will be noted that the envelope
lines 90, 92 and the heights of adjacent peaks do not present as
clean of a "bell-shaped" configuration as do the envelope lines 70,
82 of the normal patients of FIGS. 1a and 1b respectively. Turning
now to the peak heights, which form the basis for the creation of
the envelope lines 90, 92, it will be noted that the heights of
adjacent peaks tend to be more varied with regard to whether they
are higher or lower than the peaks adjacent to them. For example,
turning now to FIG. 2b, it will be noted that the heights of four
adjacent peaks 90, 93, 94, 96 are such that the height of peak 90
is greater than the height of peak 93, the height of peak 93 is
less than the height of peak 94, and the height of peak 94 is
greater than the height of peak 96. Within this small stretch, the
slope of the envelope line would be undulating, caused by the
sequence of the relatively higher (90), relatively lower (93),
relatively higher (94), and relatively lower (96), peak heights of
the four adjacent peaks. Nonetheless, it will be noted that the
undulation shown in the time dependant pulse wave form data of
FIGS. 2a and 2b is slight, and may be difficult to detect without
careful observation.
Your attention is now directed to FIGS. 3a and 3b, which show a
pair of patients (here known as patients 3a and 3b) who suffer from
severe aortic regurgitation. First, it will be noted that the
envelope lines 100, 102 which are drawn between adjacent peaks of
the time dependant pulse wave form data shown in FIGS. 3a and 3b,
each have an undulating slope. This undulating nature is best shown
in FIG. 3b with reference to five adjacent peaks, including first
adjacent peak 104, second adjacent peak 106, third adjacent peak
108, fourth adjacent peak 110, and fifth adjacent peak 112, having
heights H.sub.1, H.sub.2, H.sub.3, H.sub.4 and H.sub.5
respectively. It will be noted that with these peaks, the following
is true: H.sub.1 (104)>H.sub.2 (106); H.sub.2 (106)<H.sub.3
(108), H.sub.3 (108)>H.sub.4 (110) and H.sub.4 (110)<H.sub.5
(112). This pattern gives rise to the undulating slope of envelope
line 102. Because of the severity of the aortic regurgitation of
the patients whose data is shown in FIGS. 3a and 3b, the
undulations within the envelope line 102, 100 are easily visible to
even the uninitiated and can be easily diagnosed as such. The
patients whose data is shown in FIG. 3a and 3b were determined by
an echo-cardiograph to have level 3 (severe) aortic regurgitation.
To the contrary, the patients whose data is shown in FIGS. 2a and
2b were determined by echo-cardiograph to have level one (mild)
aortic regurgitation.
As may be apparent from the discussion above, and review of FIGS.
2a and 2b, the use of time dependant pulse wave form data enables
the user to easily diagnose the existence of severe aortic
regurgitation in patients. However, the diagnosis is more difficult
for patients having a more mild degree of aortic regurgitation.
Therefore, it would be helpful if the patient data could be
processed in a manner that leads more easily to the identification
of those characteristics which suggest the presence of aortic
regurgitation. These characteristics can be more easily displayed
if the data is processed to convert the time dependant wave form
data to an array of frequency dependant wave form data. This
conversion is best accomplished by using a Fourier transformation.
The data processing means 36 of the present invention can be used
in conjunction with the fast Fourier transform program set forth
above to convert the time dependant pulsation signal shown in FIGS.
1a-3b to the frequency dependant data shown in FIGS. 4a-6b.
Turning now to FIGS. 4a and 4b, it will be noted that a first
series of signals designated as M.sup.1, M.sup.2, M.sup.3, M.sup.4
and M.sup.5 exist. These signals M.sup.1- M.sup.5 are the "main"
signals, which are representative of the forward flow of fluid out
of the ventricle, and through the aortic valve into the aorta.
These signals are frequency dependant, and plot the amplitude of
the signal, as a function of the frequency.
It will be noted that the "main" frequency signals appear on a
graph at frequencies of approximately 100, 200, 300, 400, and 500
Hertz. It will also be noted that a second series of associated
peaks designated as N.sup.1, N.sup.2, N.sup.3, N.sup.4 and N.sup.5
exist. These associated peaks, are lower than the main peaks
(M.sup.1 -M.sup.5) but are generally closely associated with the
main peaks. Importantly, these second series of peaks (N.sup.1
-N.sup.5) appear at frequencies of approximately 90, 190, 290, 390,
and 490 Hz. Since the frequencies of these peaks are not at
integral multiples of a fundamental frequency, they are not
harmonic, and are treated as noise. If the signals were harmonic,
and the first noise signal N.sup.1 appeared at a fundamental
frequency of 90 Hz, then the second noise signal N.sup.2 would have
appeared at twice the fundamental frequency
F(N.sup.2)=F(N.sup.1).times.2, approximately 180 Hz. Similarly,
N.sup.3 would have appeared at three times the fundamental
frequency, F(N.sub.3)=F(N.sup.1).times.3, approximately 270 Hz;
N.sup.4 would have appeared four times the fundamental frequency,
F(N.sub.4)=F(N.sup.1).times.4, approximately 360 Hz; and N.sup.5
would have appeared at five times the fundamental frequency,
F(N.sub.5)=F(N.sup.1).times.5, approximately 450 Hz. However, this
is not the case. Because these noise signals are not harmonics,
these noise signals do not indicate the existence of aortic
regurgitation. As such, the absence of any harmonic signals would
tend to indicate the absence of any aortic regurgitation.
Although the noise signals N.sup.1 -N.sup.5 of FIG. 4b have a
different shape, noise signals N.sup.1 -N.sup.5 are also not
harmonic signals. In this regard, it should be noted that main
signals M.sup.1 -M.sup.5 of FIG. 4b appear at integral multiples of
a fundamental frequency of approximately 92 Hz. Thus, M.sup.1
appears at approximately 92 Hz, signal M.sup.2 appears at
approximately 184 Hz, signal M.sup.3 appears at approximately 276
Hz, signal M.sup.4 appears at approximately 368 Hz, and signal
M.sup.5 appears at approximately 460 Hz. Thus, a harmonic
distribution is demonstrated with respect to the main signals. This
is not the case however with the noise signals of FIG. 4b.
Your attention is now directed to FIGS. 5a and 5b, which correspond
generally to the data of the patients shown in FIGS. 2a and 2b
respectively. As stated above, the patients of FIGS. 2a and 2b were
determined, by echo-cardiograph to have mild aortic
regurgitation.
Turning now to FIG. 5a, the main signals M.sup.1 -M.sup.4 appear at
integral multiples of the fundamental frequency of 120 Hz, M.sup.1
appears at 120 Hz, M.sup.2 appears at 240 Hz, M.sup.3 appears at
360 Hz and M.sup.4 appears at 480 Hz. Similarly, a second series of
signal peaks, which reflect aortic regurgitation, are designated by
letters R.sup.1, R.sup.2, R.sup.3, and R.sup.4. These regurgitation
signals R.sup.1 -R.sup.4 are associated with the respective main
peaks M.sup.1 -M.sup.4, respectively, but are harmonically
distributed along the frequency axis, at integral multiples of a
fundamental frequency of about 114 Hz. In this regard, it should be
noted that regurgitation signal R.sup.1 is positioned at
approximately 114 Hz, R.sup.2 at approximately 228 Hz, R.sup.3 at
approximately 342 Hz and R.sup.4 at approximately 456 Hz.
Turning now to FIG. 5b, it will be noted that the second series of
signals, R.sup.1 -R.sup.5 are harmonic. In the example shown in
FIG. 5b, the peaks of the main signals occur at integral multiples
of the fundamental frequency of 89 Hz, thus occurring at
approximately 89 Hz (M.sup.1), 178 Hz (M.sup.2), 267 Hz (M.sup.3),
356 Hz (M.sup.4), and 445 Hz (M.sup.5). Similarly, peaks of the
second series of signals R.sup.1 -R.sup.5 occur at multiples of the
fundamental frequency of 86 Hz, thus appearing at approximately 86
Hz (R.sup.1), 172 Hz (R.sup.2), 258 Hz (R.sup.3), 344 Hz (R.sup.4)
and 430 Hz (R.sup.5).
In FIGS. 5a and 5b, the existence of the second series of
harmonically occurring regurgitation signals R.sup.1 -R.sup.5
indicates the existence of some level of aortic regurgitation
within the patients of FIGS. 5a and 5b. Because of the
frequency-dependant manner in which the data is displayed, these
characteristics indicative of the aortic regurgitation can be
determined more easily for patients having low levels of aortic
regurgitation, such as the level-1 aortic regurgitation patients
for whom the data of FIGS. 5a and 5b was taken.
Your attention is now directed to FIGS. 6a and 6b, which show
frequency dependant data from patients whose time dependant array
of data is shown in FIGS. 3a and 3b. It will be recalled that the
patients of FIGS. 3a and 3b were characterized as having severe
aortic regurgitation by an echocardiograph test. Turning now to
FIG. 6a, it will be noted that there is shown a series of main
signals M.sup.1 -M.sup.5, which reflect the flow of fluid forwardly
through the aortic valve, and a series of harmonic regurgitation
signals R.sup.1 -R.sup.5 which are reflective of aortic
regurgitation. Unlike signals N.sup.1 -N.sup.5 of FIGS. 4a and 4b,
signals R.sup.1 -R.sup.5 are harmonic signals, occurring at
integral multiples of a fundamental frequency of about 82 Hz.
Your attention is now directed to FIG. 6b. FIG. 6b shows a series
of four main peaks M.sup.1, M.sup.2, M.sup.3, and M.sup.4, and
eight regurgitation peaks (R.sup.1 -R.sup.8) which are indicative
of aortic regurgitation. It will be noted that the fundamental
frequency of the main signal is an integral multiple of the
fundamental frequency of the regurgitation signal, thus causing the
peaks of the two signals to overlap. For example, the first peak
M.sup.1 appears at approximately 118 Hz, whereas the corresponding
regurgitation signal R.sup.1 appears at approximately 59 Hz and the
second peak appears at 118 Hz, overlapping with M.sup.1. As such,
over a given frequency range of 0-500 Hz, as shown in the drawing,
twice as many regurgitation signals exist as main flow signals, due
to the fact that the fundamental frequency of the regurgitation
signals is one-half the fundamental frequency of the main
signal.
It has been found by the applicants that much useful information
can be derived about the nature of the aortic regurgitation, and in
particular, about the relative volume of aortic regurgitant flow by
comparing the signals representative of the main flow forwardly
through the aortic valve (e.g. M.sup.1 -M.sup.5), to the signals
representative of the regurgitant flow of fluid, represented by the
regurgitation signals (e.g. R.sup.1 -R.sup.5).
Turning now to each of FIGS. 5a-6b, it will be noted that each of
the main flow signals have an amplitude A.sub.1 which corresponds
to the height of the peaks. Similarly, the regurgitation flow
signals R.sup.1 -R.sup.5 also have an amplitude A.sub.2. By
comparing the amplitude of the regurgitation flow signals to the
amplitude of the main signals, one can obtain some
semi-quantitative analysis of the relative volume of the
regurgitation flow, to the main flow. This semi-quantitative
analysis can be performed through the equation A.sub.2 +A.sub.1,
wherein A.sub.2 equals the amplitude of the regurgitation flow
signals (R.sup.1 -R.sup.5), and A.sub.1 equals the amplitude of the
main flow signals (M.sup.1 -M.sup.5). This can be done by using one
main signal (e.g. M.sup.3), and one corresponding regurgitation
signal (i.e. R.sup.3), or by using several signals.
Turning now to Table 1, this analysis was performed wherein the
Amplitude A.sub.2 of the second harmonic R.sup.2 was divided by the
amplitude A.sub.1, of the second harmonic of the main signal
M.sup.2. However, for FIG. 6b, because of the overlap, R.sup.2 was
approximated as (R.sup.1 +R.sup.3)/2. For the main signal, M.sup.2
was derived by a calculation which sought to subtract the R.sup.4
contribution at the second harmonic of the main signal M.sup.2.
Thus the equation (M.sup.2 +R.sup.4)-(R.sup.3 +R.sup.5)/2=M.sup.2
was used, as shown in Table 1.
TABLE 1 DYNAPULSE WAVEFORM FFT FREQUENCY ANALYSIS: Identify aortic
"Regurgitation", A.R., wave spectrum (R) & Estimate its weight
(in %) vs. "Main" pulse wave spectrum (M). Frequency R2/M2 CASE-#
(Hz) i = 1 i = 2 i = 3 i = 4 i = 5 (.times.100%) NOTES AR CASES:
f(M1) f(R1) [f(Mi) - f(Ri)] (Hz) SEVERE-1 1.04 1.00 0.03 0.07 0.10
0.13 0.16 55% SEVERE-2 1.36 0.68 0.67 1.34 2.00 2.67 44% * MILD-1
1.46 1.38 0.07 0.15 0.20 0.27 26% MILD-2 1.09 1.05 0.04 0.08 0.12
0.15 0.22 20% NORMAL CASES: f(M1) f(N1) [f(Mi) - f(Ni)] (Hz): N =
Noise NORMAL-1 1.21 1.13 0.08 0.08 0.08 0.08 0.08 0% ** NORMAL-2
1.12 1.04 0.08 0.08 0.08 0.08 0.08 0% *Due to overlap of R and M
spectra, R2 and M2 were calculated by following equation: R2 = (R1
+ R3)/2 M2 = (M2 + R4) - (R3 + R5)/2; ASSUMING R4 = (R3 + R5)/2
**"Noise" FFT signals (N) associate to the "Main" spectrum signals
at a fixed distance in frequency domain, ie. [f(Mi) - f(Ni)] =
constant. Where, "Regurgitation" FFT spectrum signal had the [f(Mi)
- f(Ri)] value that increased from i = 1 to i = 5 and as a multiple
of i.
Turning now to the second-to-the-last column of Table 1, it will be
noted that the approximate percentage of regurgitation volume to
main volume was 55% and 44% for the respective patients whose data
is shown in FIGS. 6a and 6b respectively. As set forth in more
detail above, these patients were both diagnosed to have severe
aortic regurgitation.
For the patients whose data is shown in FIGS. 5a and 5b, who were
diagnosed with a more mild aortic regurgitation, the regurgitation
volumes were calculated to be 26%, for the patient of FIG. 5a, and
20%, for the patient of FIG. 5b.
As the patients whose data is shown in FIGS. 4a and 4b had no
regurgitation, as their signal display lacked any harmonic
regurgitation signal, these patients were diagnosed as having a "0"
percent regurgitation flow.
To achieve the calculations shown in Table 1, the various
amplitudes of the signals were measured and compared. However, it
is also possible, and may be advisable to compare the "density" of
the two signals to each other, as such a density measurement would
also tend to lead to a semi-quantitative analysis of the
regurgitation flow relative to the forward flow. Such a comparison
of density could be done by determining the area under the
respective signals (e.g. M.sup.1, R.sup.1), and comparing them in a
manner similar, such as by dividing the area under the regurgitant
flow signal (D.sub.2) by the area under the main signal (D.sub.1),
by the equation regurgitant relative volume percentage equals
D.sub.2 +D.sub.1.
Additionally, other computer modeling methods may be used to help
determine relative flow volume.
It is also believed that the frequency shift between the position
of the main signal (e.g. M.sup.1) and its correspondent
regurgitation signal (R.sup.1) will provide valuable data about the
nature, type and characteristics of the aortic regurgitation of the
patient.
* * * * *