U.S. patent application number 15/006926 was filed with the patent office on 2016-05-19 for portable electronic hemodynamic sensor systems.
The applicant listed for this patent is CALIFORNIA INSTITUTE OF TECHNOLOGY. Invention is credited to Morteza Gharib, Niema Pahlevan, Derek Rinderknecht, Peyman Tavallali.
Application Number | 20160135697 15/006926 |
Document ID | / |
Family ID | 53681873 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160135697 |
Kind Code |
A1 |
Rinderknecht; Derek ; et
al. |
May 19, 2016 |
PORTABLE ELECTRONIC HEMODYNAMIC SENSOR SYSTEMS
Abstract
Systems and methods are provided for extracting hemodynamic
information, optionally employing portable electronic devices with
optional User Interface (UI) features for system implementation.
The systems and methods may be employed for acquiring hemodynamic
signals and associated electrophysiological data and/or analyzing
the former or both in combination to yield useful physiological
indicia or results. Such hardware and software is advantageously
used for non-invasively monitoring cardiac health.
Inventors: |
Rinderknecht; Derek;
(Arcadia, CA) ; Pahlevan; Niema; (Pasadena,
CA) ; Tavallali; Peyman; (Pasadena, CA) ;
Gharib; Morteza; (Altadena, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CALIFORNIA INSTITUTE OF TECHNOLOGY |
Pasadena |
CA |
US |
|
|
Family ID: |
53681873 |
Appl. No.: |
15/006926 |
Filed: |
January 26, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14601170 |
Jan 20, 2015 |
|
|
|
15006926 |
|
|
|
|
61992044 |
May 12, 2014 |
|
|
|
61992035 |
May 12, 2014 |
|
|
|
61932576 |
Jan 28, 2014 |
|
|
|
61929880 |
Jan 21, 2014 |
|
|
|
Current U.S.
Class: |
600/479 ;
600/500 |
Current CPC
Class: |
A61B 5/6898 20130101;
A61B 5/021 20130101; A61B 5/742 20130101; A61B 5/024 20130101; A61B
7/04 20130101; A61B 5/0408 20130101; A61B 5/0402 20130101; A61B
7/02 20130101; A61B 5/7275 20130101; A61B 5/02427 20130101; A61B
5/02028 20130101; A61B 2560/0431 20130101; A61B 5/0002 20130101;
A61B 5/0261 20130101; A61B 5/6822 20130101; A61B 5/725 20130101;
A61B 5/0285 20130101; A61B 5/0059 20130101 |
International
Class: |
A61B 5/024 20060101
A61B005/024; A61B 7/02 20060101 A61B007/02; A61B 5/02 20060101
A61B005/02; A61B 5/00 20060101 A61B005/00; A61B 5/0408 20060101
A61B005/0408 |
Claims
1-25. (canceled)
26. A system comprising: a vibration sensor adapted to capture a
vibrational signal, and a computer processor, wherein the computer
processor is adapted to resolve each of a pulse pressure waveform
and an Embedded Frequency corresponding to sound of the heart from
the vibrational signal, and wherein the processor is further
adapted to, using the Embedded Frequency and the pulse pressure
waveform, calculate at least one physiological parameter.
27. The system of claim 26, wherein the physiological parameter is
selected from at least one of Dicrotic Notch (DN) position of the
pulse pressure wave form, Ejection Fraction (EF) and systolic time
intervals.
28. The system of claim 27, wherein the computer processer is
further adapted to calculate Intrinsic Frequency (IF) parameters
.omega..sub.1 and .omega..sub.2 on each side of the DN.
29. The system of claim 26, wherein the vibration sensor comprises
a light source and a light sensor.
30. The system of claim 29, wherein the light sensor is an LED in a
smartphone camera.
31. The system of claim 29, wherein the vibration sensor further
comprising a membrane, the membrane made of a material selected to
be at least partially reflective to the light source on an inner
surface of the membrane.
32. The system of claim 31, wherein the membrane comprises metal or
is metalized on the inner surface.
33. The system of claim 31, wherein the membrane material is
selected to reduce light passing from an outer surface of the
membrane to the sensor.
34. The system of claim 33, wherein the material substantially
eliminates light passing from the outer surface.
35. The system of claim 33, wherein the membrane comprises metal or
is metalized on at least one surface.
36. The system of claim 26, further comprising an electrocardiogram
(ECG) sensor, wherein the processor is further adapted for
producing an ECG signal.
37. The system of claim 36, wherein the computer processor is
further adapted to calculate Ejection Fraction (EF) using the
Embedded Frequency, the pressure waveform and the ECG signal.
38. A method comprising: positioning a vibration sensor on a
subject's skin at a location peripheral to a the subject's heart,
capturing a vibrational signal of skin motion, resolving the
vibrational signal into each of a pressure waveform signal and an
Embedded Frequency signal corresponding to sound of the heart, and
calculating with a computer processor, using the Embedded Frequency
signal and the pulse pressure waveform signal, at least one
physiological parameter
39. The method of claim 38, further comprising determining a
Dichroitic Notch (DN) position within the pressure waveform signal
using the Embedded Frequency signal with the computer
processor.
40. The method of claim 38, further comprising calculating
Intrinsic Frequency (IF) parameters .omega..sub.1 and .omega..sub.2
with the computer processor.
41. The method of claim 40, further comprising calculating Ejection
Fraction (EF) with the computer processor using .omega..sub.1 and
.omega..sub.2.
42. The method of claim 38, further comprising: positioning a
plurality of electrocardiogram sensors on the subject, and
detecting an electrocardiogram (ECG) signal.
43. The method of claim 42, further comprising calculating Ejection
Fraction (EF) using the Embedded Frequency signal, the pressure
waveform signal and the ECG signal with a computer processor.
44. The method of claim 44, wherein the vibration sensor detects
light intensity reflected from a source.
45. The method of claim 44, wherein the detected light intensity is
reflected off of a membrane.
46. The method of claim 45, wherein the light intensity is
reflected off a metal or metalized surface of the membrane.
47. The method of claim 45, wherein the light intensity is
substantially free of background light transmitted through the
membrane.
48. The method of claim 38, performed with a handheld device.
49. The method of claim 48, wherein the handheld device is a
smartphone.
50. The method of claim 48, wherein the vibration sensor and a
first ECG electrode, both at a face of the handheld device are
positioned together, and the method further comprises selecting a
second ECG electrode from a finger electrode of the device and a
plug-in electrode for the device and contacting the subject's skin
at a second location with the selected sensor contact.
51-110. (canceled)
Description
RELATED APPLICATIONS
[0001] This filing is a continuation application of U.S. patent
application No. 14/601,170, filed Jan. 20, 2015, which claims the
benefit of and priority to U.S. Provisional Patent Application Ser.
No. 61/929,880, filed Jan. 21, 2014, Ser. No. 61/932,576, filed
Jan. 28, 2014, Ser. No. 61/992,035, filed May 12, 2014, and Ser.
No. 61/992,044, filed May 12, 2014, all of which are incorporated
by reference herein in their entireties and for all purposes.
FIELD
[0002] The present subject matter relates to devices and methods
for obtaining and utilizing hemodynamic waveform measurements.
BACKGROUND
[0003] Cardiovascular diseases (CVDs) are the underlying cause of
about one of every three deaths in United States each year. About
34% of American adults are suffering from one or more types of CVD.
In 2010, the total direct and indirect cost of CVDs was
approximately $503 billion.
[0004] There is an urgent need to develop new methods and devices
for diagnosing and monitoring CVDs. Diagnosis enables early
intervention and remediation. Monitoring is a useful tool in
behavior modification and in the prediction and subsequent
avoidance of acute events that can lead to emergency
hospitalization, morbidity, and/or mortality. New methods and
devices to meet these need(s) advantageously enable extracting
hemodynamic information from or in connection with a portable
electronic device.
SUMMARY
[0005] Example embodiments of systems and methods are provided for
acquiring and/or utilizing hemodynamic information, optionally, in
connection with portable electronic devices. As such, a portable
approach for the quantification of cardiovascular physiology and
diagnosis of cardiovascular disease (CVD) is provided that can
operate utilizing a mobile communication device (e.g., smartphone)
platform. An optional User Interface (UI) and/or other features
adapted for hemodynamic signal acquisition may be incorporated for
system implementation.
[0006] In certain system embodiments, a smartphone, a
hardware-modified smartphone, a peripheral instrument or sensor(s)
wired or wirelessly connected to a smartphone, or other portable
electronic devices can be used to obtain physiological waveform
data. Once a physiological waveform has been acquired, the data can
be stored locally or on a server (e.g., the "Cloud"). The waveform
may be analyzed remotely (e.g., by or in the Cloud) or locally.
[0007] Certain calculations involving the waveform(s) may employ an
Intrinsic Frequency (IF) method, a sparse time frequency
representation (STFR) algorithm, or any other empirical mode
decomposition based method. Other approaches are referenced below
as well.
[0008] Various physiological parameters may be calculated from the
obtained physiological waveform(s). In one embodiment, left
ventricular Ejection Fraction (EF) can be calculated and displayed
to the user. In another embodiment, Stroke Volume (SV) and/or
Cardiac Output (CO) can be calculated. For either such
determination, see U.S. patent application Ser. No. 14/517,702,
filed Oct. 17, 2014, and titled, "INTRINSIC FREQUENCY ANALYSIS FOR
LEFT VENTRICLE EJECTION FRACTION OR STROKE VOLUME DETERMINATION,"
incorporated by reference herein in its entirety and for all
purposes. Another approach to determining EF may be adapted from
"The Relationship of Alteration in Systolic Timer Intervals to the
Ejection Fraction in Patients with Cardiac Disease," Circulation.
1970; 42: 455-462 with related systolic time intervals determined
by reference to "Systolic Time Intervals in Heart Failure in Man,"
Circulation. 1968; 37:149-159 and "The Relationship of Alterations
in Systolic Time Intervals to Ejection Fraction in Patients with
Cardiac Disease," Circulation. 1970; 42: 455-462, both of which are
incorporated by reference herein in their entirety for all
purposes. In yet another example embodiment, IF values
(.omega..sub.1, .omega..sub.2) are calculated and a health status
determination can be displayed. For such determinations, see USPPN
2013/0184573, also incorporated by reference herein in its entirety
for all purposes.
[0009] The embodiments described herein can obtain
electrocardiogram (i.e., EKG or ECG), phonocardiogram, and arterial
pulse waveforms. These embodiments can include an optical sensor
for the measurement of the arterial pulse waveform and/or heart
sound. Optical detection may be accomplished by a LED or photodiode
combination. In another embodiment, a pulse wave may be recorded
via microwaves. A microwave transceiver may be located behind the
screen of the mobile communication device for such purpose.
[0010] Regarding specific hardware implementations, one example
embodiment involves quantification of cardiovascular physiology and
diagnosis of CVD utilizing a standard smartphone platform
(typically in connection with customized hardware and/or software).
These embodiments exploit the analog signal from a camera in
combination with the camera LED flash to measure the reflectance of
light off the skin in the proximity of an artery passing near the
surface of the skin to quantify its radial expansion in response to
a time varying blood pressure. Such an approach optionally involves
a series of components: using a camera integrated in a portable
electronic device to record the motion of the skin to capture the
shape of the blood pressure waveform, user feedback provided
through visual and/or auditory signal(s) enabling the enhancement
of signal quality, and the design of the data display and analysis.
Although the approach is described herein in terms of
cardiovascular waveforms, a variety of waveforms can be analyzed
employing such a platform.
[0011] In certain embodiments where such systems are used, a user
locates a pulse where a major arterial passes near the surface of
the skin and places the phone such that the camera and LED both
image and illuminate the location respectively. A prepare screen
then begins to display the relative motion of the skin. In one
embodiment, the average intensity of the camera signal is used to
create a signal describing the relative motion of an artery. In
another embodiment, only particular regions of the camera image are
subjected to averaging, although more elaborate image processing
schemes are possible for such information as known by those skilled
in the art that may be applied hereto. In addition, the device's
LED intensity may be adjusted to maintain an adequate
signal-to-noise ratio for the waveforms being acquired by the
device. The LED may also be strobed in a manner that cuts down on
noise (e.g., by offsetting from or screening out other frequencies
where noise is present). For example, the LED can be pulsed at a
frequency above what common electronics use. In some embodiments,
the LED strobing frequency may be between 500 Hz and 1 GHz or more
preferably in the range of 2 kHz to 64 kHz.
[0012] In another embodiment, the waveform may be obtained through
a peripheral instrument such as a wired pulse oximeter. Indeed, the
waveform may be acquired through any of microwave, strain-gauge,
piezoresistive, capacitive, optical, or acoustic sensors. A
combination or multiplexing of sensors may be used. For example, an
array of LEDs and detectors camera or photodetectors may be used to
analyze the motion of the skins surface. In one embodiment the
detector is a phototransistor. In another embodiment, the detector
is a photodiode. Such instruments may be connected through a
microphone jack to a/the smartphone. In some embodiments, the
peripheral instruments are connected wirelessly such as through
WiFi or BLUETOOTH.
[0013] To accommodate different body types, a probe-style
peripheral sensor (e.g., in a stethoscope-type shape) with a
detector and an array of LEDs may be used. Such a probe may also be
adapted to perform an ECG. The probe may include one or more ECG
sensor contacts leads or electrodes on the probe head for such
purposes. In another embodiment, the probe has one or more ECG
electrodes on the probe head and at least one additional electrode
on a grip portion, thereby providing an increased measurement path
if the device is held in position by the user. In another
embodiment, the probe has a secondary connection to add an
additional ECG electrode for the case where an operator is holding
the device for the subject. In this case, the grip portion ECG
electrode is optionally deactivated.
[0014] The above offers an example of a so-called "multiplexing
sensor." Another embodiment includes a waveform detecting sensor,
ECG electrodes and a microphone combined into a peripheral data
probe. This or another probe may also measure blood pressure,
hydration, skin impedance, temperature, the waveform as well as a
phonocardiogram.
[0015] In another embodiment, the sensor device is enclosed in a
specialized case to enhance waveform acquisition (e.g., as in the
example of smartphone hardware). This case may integrate a
multitude of sensors. The case may include optical components such
as lenses allowing the location and direction of the incoming
optical signal to be adjusted according to body type and skin
rigidity. Case hardware may also be provided to set a standoff
distance for the device camera and LED that are adjustable between
about 10 .mu.m to about 10 cm. A mechanical add-on to the device
case (or directly to the smartphone) may be provided to enable
relative positioning and/or tensioning of the skin.
[0016] In one example of skin tensioning hardware, a ring with
various deflectable, deformable and/or stop features as detailed
below may be employed. In another example, a sensor membrane may be
provided in the (optical) sensor system. The membrane may comprise
any number of plastics, animal skin, and/or rubber. A polyester or
polyurethane membrane may be preferred.
[0017] Whether employed in connection with skin-tensioning hardware
configurations or adaptations or merely as a sensor interface in
use, the membrane is located or placed in contact with the skin
where signal acquisition is desired (i.e., between the optical
sensor and the skin). The thickness of the membrane and material
from which it constructed (e.g., rubber, plastic, metal or
composite material) is chosen to exhibit mechanical properties that
allow the membrane to follow the underlying pulse waveform and
record the same. As such, the membrane may have a thickness is in
the range of about 12 to about 500 .mu.m. The membrane may cover a
diameter ranging from 1 mm to 50 mm. The optical properties of the
membrane may be chosen such that it reflects at the wavelengths of
the LED incorporated in the smartphone (or used in a separate
device) and ambient light to otherwise decrease signal noise. It
may be optically opaque at the wavelength or wavelengths of
detection.
[0018] Indeed, the membrane serves a number of functions such as
normalizing for subjects skin tone, acoustic coupling for
phonocardiographic measurements as well as providing a sterile and
disposable barrier for testing. In another embodiment, the membrane
is not disposable.
[0019] When the membrane is disposable it may snap, press-fit, or
screw in place. In another embodiment, the membrane is housed in
another component that couples it to the handheld sensor device.
The membrane may have a rigid frame. Use of such a membrane
incorporated in a hemodynamic sensor device (as in a device for
direct attachment to a smartphone and/or as incorporated in a
stand-alone sensor embodiment) serves the purpose of increased
robustness to user skin tone and body topography. As to further
details of its operation of the membrane for use in pressure
waveform monitoring in connection with a light source (be it an
LED, laser or otherwise), these can be appreciated in reference to
U.S. Pat. No. 5,363,855 incorporated herein by reference in its
entirety for all purposes.
[0020] The membrane may have multiple regions with different or
varying material properties. In another embodiment, additional
constraints or structures may be used to enhance signal quality. In
another embodiment, the device may not have a membrane.
[0021] In addition to picking up a pulse waveform from skin
vibration caused by underlying arterial motion, the subject
membrane-based sensor arrangement (including a light source and
sensor for light reflected from the membrane) is able to detect a
higher frequency range of vibrations corresponding to the so-called
heart sounds. Notably, these sounds are offset in timing from heart
sounds that can be detected over a subject's heart (i.e., in the
region of the sternum).
[0022] The nature of heart sounds that may be detected at a
peripheral locations were the subject of some study roughly
half-a-century prior to the subject filing. Particularly, Farber et
al., in "Conduction of Cardiovascular Sound Along Arteries," Circ.
Res. 1963; 12:308-316, discussed the origin of heart sounds that
may be detected at a peripheral location as well as their mode of
propagation. The inventors hereof believe that those authors
properly concluded that the heart sounds that may be detected at
peripheral location(s) ride upon or are embedded with the blood
pressure wave. Embodiments provided herein apply such information
to practical use for complex calculation of physiological
parameters.
[0023] In these embodiments, the heart sounds that are generated
(i.e., resolved or separated as further discussed below) from the
vibration signals obtained are referred to herein as Embedded
Frequency signals or Embedded Frequencies. The heart sounds may be
acquired optically and isolated by amplifying and filtering. The
heard sounds may be isolated by high pass filtering the pulse
waveform. The filtering may be achieved by mechanical filtering or
by the response bandwidth of a transducer as in the case of a
microphone.
[0024] As detailed further below, the properties and timing
(especially its synchronicity relative to the pulse waveform) of
the Embedded Frequency signals offers great utility in interpreting
the features of the pulse pressure waveform and other possible
utility heretofore unused and/or problematic to otherwise
derive.
[0025] Additional embodiments hereof include various improved
techniques for signal acquisition. These techniques may be
integrated into the UI of the subject devices and/or accomplished
through interaction with a peripheral marker, beacon or service.
Any of these various audio and/or visual indicators discussed below
may be regarded as various selectable signaling means.
[0026] In one set of examples, an auditory signal is assigned the
information streaming from the camera in the sensor device
platform. For example, each camera frame may be averaged and turned
into a single instantaneous point, therefore a frame rate of 30 fps
produces a (background auditory) signal of 30 Hz. In another
embodiment, the camera or sensor acquisition rate ranges from 10 Hz
to 100 kHz. In another embodiment, the auditory signal is produced
by multiplying or modulating a background auditory signal such as
white noise by the incoming data. In another embodiment, the time
derivative of the incoming data is multiplied by a background
auditory signal. In another embodiment, the incoming data is
manipulated through a mathematical operator. In another embodiment,
the background signal is brown noise, pink noise or of a single
frequency. In another embodiment, the background sound is user
customizable. In sum, the exact details or feel of the background
auditory signal modulated by the physiological waveform data is
left up to those skilled in the art. Nevertheless, the sound (i.e.,
background auditory signal) may be rescaled to still be audible for
weak signals. The auditory cutoff for this sound may be used to
indicate a minimum threshold for a usable signal.
[0027] In another set of examples for optimizing signal acquisition
location, the user is prompted visually or audibly to move
locations until the signal possesses a particular quality or span.
This sound may have the recognizable character of a
phonocardiogram. Such an auditory feedback signal may be used to
allow the user to home in on the optimal location based on (audibly
detected) waveform shape and intensity. Alternatively, the auditory
feedback may take the form of a beep or similar noise. The
frequency of beeping may increase as sensor device position is
improved by the user to improve acquired signal quality. Once
achieved, a position "lock" may be indicated by a constant
tone.
[0028] In another embodiment, acquisition signal quality is
indicated by an indicator light. This indicator may be an icon on
the screen of a/the smartphone and/or peripheral device.
Alternatively, the visual signal may take the form of a slide or
meter. Such a meter may comprise a series of collinear dots or the
meter may rotate like a clock or speedometer. Another such meter
may comprise a target or series of concentric rings which are
illuminated towards the center and/or flash in a similar
pattern.
[0029] In another embodiment, signal quality indices are applied to
screen the incoming physiological waveforms. These signal quality
indices may be based on the timing, span, or shape of the waveform
or combinations thereof. These indices may be used to communicate
with the user to prompt improved positioning, retaking of data or
other (re)action. Likewise, machine learning or neural network type
algorithms may be utilized to screen poor waveforms and/or alert
the user to properly acquired physiological waveform data.
[0030] In another embodiment, a locator system may be provided in
connection with a physical marker or external device which has
communicated or is in communication with the waveform acquisition
system. Conventional positional triangulation techniques and RF or
other signaling may be used for such purposes. In another
embodiment, a directional microphone targeted to the location of
maximum sensitivity of the camera may be used to detect the optimum
location/position. In another embodiment, a focused LED or low
power laser is used to roughly indicate the center of the sensor
area to the user.
[0031] In yet another embodiment, locating the sensor device for
optimal signal acquisition may be achieved in connection with a
constant marker preferably not (although possibly) seen by the
user. Such a marker may comprise an IR skin tag or IR tattoo
viewable only to the camera and illuminated via the LED. In one
embodiment, these are alignment marks indicating position as well
as orientation. As another alternative, an injectable skin tag in
the form of a small metallic or ferromagnetic component may be
used. The injectable skin tag may comprise an RFID chip or other
small electronic device.
[0032] More generally, embodiments hereof include systems
(including the sensor hardware referenced herein and the addition
of a computer processor and other ancillary/support electronics and
various housing elements), methods (including software and
associated hardware for carrying out specified acts) and UI
features (including layouts and options and/or methodology
associated with system use). Many of the subject device and/or
system embodiments may be adapted for wearable as well as hand-held
use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The figures provided herein may be diagrammatic and not
necessarily drawn to scale, with some components and features
exaggerated and/or abstracted for clarity. Variations from the
embodiments pictured are contemplated. Accordingly, depiction of
aspects and elements in the figures are not intended to limit the
scope of the claims, except when such intent is explicitly
stated.
[0034] FIGS. 1A and 1B are diagrams illustrating dynamic coupling
of the heart and aorta in a human circulatory system.
[0035] FIG. 2 is a cutaway anatomical illustration showing device
positioning for signal acquisition.
[0036] FIG. 3 is a system overview including exemplary hardware of
one embodiment.
[0037] FIGS. 4A and 4B are opposite face-side views of smartphone
hardware employed in another embodiment.
[0038] FIGS. 5A and 5B are opposite-facing oblique views of a
specialized smartphone case hardware and associated hardware that
may be employed in another embodiment.
[0039] FIG. 6 is a cross-section view including optional
skin-tensioning and signal-amplification hardware.
[0040] FIGS. 7A and 7B are cross-section views illustrating use of
one of the skin-tensioning variation in connection with the
embodiment illustrated in FIGS. 5A and 5B.
[0041] FIGS. 8A-8C are cross-section views illustrating use of
another of the skin-tensioning variation that includes a sensor
membrane.
[0042] FIG. 9 is a diagram illustrating optical properties of a
selected sensor membrane.
[0043] FIGS. 10A and 10B are schematics illustrating electronics of
optical acquisition embodiments.
[0044] FIGS. 11A and 11B are diagrams of the anatomy interrogated
for hemodynamic signal acquisition.
[0045] FIG. 12 is a chart showing optically acquired hemodynamic
data.
[0046] FIGS. 13A-13C are charts variously illustrating Embedded
Frequency measurement and methodology.
[0047] FIGS. 14A-14C are flowcharts illustrating various sampling
localization optimization approaches.
DETAILED DESCRIPTION
[0048] Various example embodiments are described below. Reference
is made to these examples in a non-limiting sense. They are
provided to illustrate more broadly applicable aspects of inventive
aspects. Various changes may be made to the embodiments described
and equivalents may be substituted without departing from their
true spirit and scope. In addition, many modifications may be made
to adapt a particular situation, material, composition of matter,
process, process act(s) or step(s) to the objective(s), spirit or
scope of the claims made herein.
[0049] As pertinent to certain measurement and calculations
performed in connection with the subject systems, pressure and flow
waves generated by the heart propagate in the compliant arterial
vasculature. These waves are reflected at various reflection sites
in the arterial system. The waves carry information about the
heart, vascular system and coupling of heart and vasculature. As a
result, extracting information from these waves is of great
importance.
[0050] FIG. 1A illustrates a coupled heart-aorta system 10 in
systole, with the aortic valve open (not shown) and blood being
pumped by the heart 12 into the aorta 14. The heart and aorta
construct a coupled dynamic system before the closure of the aortic
valve. As shown in FIG. 1B, after aortic valve closure during
diastole, the heart and aorta systems are decoupled in a second
system state 10'. The aortic waves contain in each state include
information about heart dynamics, arterial network dynamic and
heart-aorta coupling. Extraction of such information by analysis
enables a variety of determinations concerning cardiovascular
health and/or various parameters as further discussed herein. The
subject technologies are of use on obtaining hemodynamic wave form
signals for such analysis and other analysis as may be desired.
[0051] As summarized above, various hardware, methodology or
software and UI features (collectively, "technologies") are
contemplated for the acquisition of hemodynamic waveform data. One
set of these technologies involves sensor device configurations
and/or processing for signal acquisition. Another set involves
signal sampling location optimization technologies. Some of these
technologies involve marking and/or locating techniques, the latter
including UI-type feedback techniques. After the physiological data
has been acquired and analyzed, it may variously yield indication
or display (i.e., on the subject portable electronic device)
instantaneous health status, heart ejection fraction, stroke volume
and/or cardiac output.
Handheld Sensor Devices and Systems
[0052] FIG. 2 provides a view of a human user or subject 20 with a
cutaway illustrating various anatomical features along with a
handheld sensor device 100 targeting the common carotid artery 22,
optionally around the carotid bifurcation 24 for hemodynamic
waveform acquisition. For this purpose, a base 102 of the device
may be separated from the skin by some distance. In one example,
this "standoff" distance is about 1 mm. Although not shown, device
100 may be held by the subject 20 or another user employing handle
interface 104.
[0053] This handheld sensor unit or device 100 may include an ECG
electrode 110 associated with the handle (e.g., as discussed
below). Signal acquisition status, prompts and/or other programming
signals or instructions may be transmitted between handheld device
100 and other system components (as further described below or
otherwise) via RF energy 120 in the form of WiFi, a BLUETOOTH
signal or using another protocol.
[0054] As referenced further below, various UI features may be
incorporated in the subject system(s). An associated element may be
in the form of a marker affixed (as in a tattoo) or implanted (as
in a biocompatible pellet or more complex device) at an optimal
spot for signal acquisition as indicated by the asterisk ("*") in
FIG. 2. Such a feature may simply indicate a target point.
Alternatively, the marker feature may include a directional
component for rotational registration. Such an approach may be
implemented employing a rod, diamond-shaped or box-shaped marker
body or indicator and/or a selected pattern applied to or implanted
within the subject's skin. FIG. 3 describes an overall system 300
including a handheld sensor device 100, a smartphone unit 200 and
an optional charger and/or sterilization unit 210 for device 100.
As illustrated, smartphone 200 communicates with/between sensor
device 100 employing signals 120/220 as in "paired" BLUETOOTH
devices or via another protocol. The smartphone may receive
information corresponding to a hemodynamic signal as further
treated below. Such a signal may be stored and/or processed via
connection with the Internet--as in so-called Cloud 202
computing.
[0055] Regarding further optional features of the handheld sensor
device 100, its perspective view included in FIG. 3 yields
additional details. Specifically, a face or facing surface 106 of
base 102 incorporates additional sensors. These may include an ECG
electrode 110', an optical sensor or sensor region 112 and/or
microphone(s) 114. Optional use of two microphones allows for
direction sound sensing for homing in on an improved or ideal
signal sensing location. As another option, a plug or port 116 may
be provided for connection to yet another ECG electrode 110'' (for
when the device is not held or operated by the user) or other
peripheral hardware (e.g., head phones for the audio signal of a
cardiophonogram (i.e., for auscultation). The handheld device 100
may be placed in a wireless charging station 210 for recharge. A UV
sterilization system may be included with the wireless charger. In
another embodiment, device 100 and its components (e.g., including
a sensor membrane as discussed further below) may comprise
materials compatible with ethanol sterilization.
[0056] FIGS. 4A and 4B illustrate an approach in which the
smartphone itself is used as the sensor means in a combined sensing
and processing device 310. Various other peripheral components may
be attached thereto as well. A direction microphone 312 may be
so-connected. Or such a microphone 312 may complement a built-in
microphone 314 to provide direction sound sensing.
[0057] In any case, the smartphone platform will typically include
a camera sensor 316 and one or more LED light or "flash" element(s)
318. Or one such element may be a focused LED or low power laser
used to roughly indicate the center of the sensor area to the user.
In any case, with the camera and incorporated lighting system(s),
the device is able to sense and capture a hemodynamic waveform.
Such information may be further processed and depicted as shown in
FIG. 4B on screen or display 320 and further commented on
below.
[0058] Device 310 may be received (as indicated by dashed line)
within a case 330 such as shown in FIGS. 5A and 5B. Features of
such a case may include an adjustable standoff feature and/or an
amplification ring structure 400. This structure may include
screw-in, twist-and-lock or snap attachment features 402 to secure
the amplification ring to the device or device case. The ring may
also include optics to further enhance the detection qualities of
the smartphone. Around a window or aperture 340 for camera or
sensor optics, case 330 may include amplification sub-system
interface features 342 complementary to features 402.
[0059] As a body 332 of the case will typically be adapted for a
given model of smartphone, its camera aperture 340 and a flash or
LED aperture 334, volume and/or lock interfaces or clearances 336
and various connector through holes 338 will be so-configured. This
body (and/or its constituent parts) may comprise plastic or any
other conventionally used smartphone case material.
[0060] FIG. 6 details further optional aspects of the so-called
amplification ring 400. Note, however, that this system element
need not be "ring" shaped. In one embodiment (i.e., as shown), the
structure is a hollow cylinder. In another embodiment, the
structure is not a cylindrical but two barriers. In another
embodiment, the structure is square in shape. While any number of
geometries are possible depending on the region of interest and
physiological signal, the exact geometry of the structure is left
up to those skilled in the art.
[0061] In any case, FIG. 6 discloses hardware and a method for
tensioning a material surface and/or underlying tissue or material
to amplify motion as a wave is transferred from one medium to
another. This method can be applied to tension the skin to increase
the sensitivity of noninvasive physiological measurements.
Generally, this method involves placing a structure 400 on top of
the skin 40 of a subject with an artery 42 passing beneath. The
structure channels the energy of a physiological signal 50--in this
case pressure waveforms as function p(x,t) generated by the
dynamics of the heart and arterial tree--within a region of
interest "ROI". As such, an amplified waveform 52--as compared to
lesser amplitude waveform 54 outside structure 400--may be
captured.
[0062] Structure 400 may also include accessories or modifications
to enhance performance as well as increase comfort. In one
embodiment, the cylinder has a rounded edge 404. In another
embodiment, the structure has a silicone or soft rubber bumper 406
at its distal interface (i.e., positioned as indicated for element
404). This bumper is able to deform to further tension skin. In
another embodiment, the bumper is in the form of an O-ring 408. In
another embodiment, the bumper is cross-sectionally formed to
include a hinge 410 utilizing lever or rim 412 action to increase
tension on the skin.
[0063] FIGS. 7A and 7B further illustrate this last variation.
Here, hinging and lever action is accomplished as evident comparing
the views once the rim or lever sections 412 are in contact with a
subject's skin 40. As shown in FIG. 7B, the system is intended to
measure movement or micro-movement (as indicated by the
double-arrow) of the skin set within or surrounded by the ROI. A
complementary threaded interface 342/402 is also shown securing a
body 420 of the amplification ring to a/the smartphone case body
332. Alternatively, such an interface may be incorporated into a
smartphone or another device. Amplification structure 400 may
include lens and/or filter elements 422 for an associated device
sensor 316 (be it a CMOS or CCD- or other light sensor) and LED 318
(or other light source) in an overall system 300.
[0064] In another amplification structure 400' embodiment,
concentric cylinders are used to provide tensioning and
amplification. FIGS. 8A-8C illustrate such an approach. Here,
structure 400 included concentric rings 430, 432. These rings may
be included in the body or base 102 of an auxiliary sensor device,
a body 320 of a smartphone device or the body 420 of an add-on
amplifier structure like that in the preceding figures. Regardless,
the interaction between a subject's skin 40 and the inner and outer
rings 430, 432 stretch the skin as shown in FIGS. 8B and 8C.
[0065] In FIG. 8B, initial contact with made with the skin along
the outer ring 432. Then, in pressing the structure 400' as
indicated by the larger arrow, contact is achieved at/around the
inner ring 430 stretching the skin and/or a membrane 440 interface
incorporated in the structure.
[0066] Use of a membrane 440 as in the above embodiment enables
further light-selective methodologies. Optical properties of the
membrane are advantageously chosen such that it reflects at the
wavelength of the LED back to the device sensor as well as blocks
noise caused by ambient light. These results may be achieved by
coloring and/or metalizing a polymer membrane (inside and/or out)
via Chemical Vapor Deposition (CVD) or otherwise. Additionally, the
membrane serves the purpose of increased robustness to user skin
tone and body topography.
[0067] These concepts are illustrated in connection with FIG. 9.
Here, exterior ambient light 442 from any source is reflected. It
may also be desirable that light from an internal source (such as
a/the LED 418) pass its visible (Vis) spectrum component(s) through
membrane 440 and only reflect its Infrared (IR) component to a/the
sensor. Such an approach can help reduce signal nose.
[0068] Most important is that external light does not pass through
the membrane to the interior of the device where the sensor(s) are
located. As such, the metalized surface may desirably set to the
outside of the device where it reflects ambient light out or
outward. As such, such an arrangement keeps all the internal light
inside the device.
[0069] Whether incorporated in an amplification "ring" structure
400/400' or simply set in or across a sensor aperture or window 340
a/the membrane 440 may comprise any number of materials such as
metals, plastics, animal skin and/or rubber. It advantageously
comprises polyester or polyurethane. Physical parameters of the
membrane are chosen to exhibit mechanical properties which allow
the membrane to follow the pulse waveform. As such, membrane
thickness is typically in the range of 12-500 .mu.m with a diameter
ranging from 1 mm to 50 mm.
[0070] As variously discussed, one application of the hardware and
subject methodology is for arterial waveform measurement. In this
regard, the amplified motion of the skin correlates to the pressure
driven expansion of an artery. The amplified motion can therefore
subsequently be recorded through any number of non-invasive
transducers such as piezoelectric, capacitive, piezoresistive,
optical, acoustic, ultrasound or electromagnetic. Similar
techniques may be applied to measure physiological wave information
that exists at different frequencies such as arterial waves versus
phonocardiograms. The signal can be recorded using an optical
reflective light sensor (e.g., with sensor 112 or 316). In another
embodiment, a combination or array of these structures may be used
to probe local arterial mechanical properties.
[0071] In the embodiment noted above, the amplification structure
is housed in a mobile phone case or employed as a (direct) mobile
phone attachment. In another embodiment, such a structure 400/400'
could be built directly into the body or housing of the phone. In
another embodiment, the structure is placed in a peripheral and/or
portable device.
[0072] In any case, system componentry for optical embodiments for
hemodynamic waveform acquisition are shown in FIGS. 10A and 10B.
These systems 500 (as may be incorporated in those above) include
an LED driver in functional block 502. A functional block 504A in
FIG. 10A for the diode/LED includes each of Low Pass (LP) filter, a
High Pass (HP) filter and an Amplifier. A functional block 504B in
FIG. 10B, again, for the diode/LED includes each of a band bass
(BP) and low pass (LP) filter and Amplifier. Via an
analog-to-digital (A/D) converter 506, the signal captured may be
passed by a communication block 508 (e.g., through BLUETOOTH
protocol) to a computer or handheld device 200 display or other
electronic hardware for processing as variously described
herein.
[0073] As to the different filtering options (i.e., differences
apparent between blocks 504A and 504B), note that the HP filter in
FIG. 10A is substituted for the BP filter in FIG. 10B. A BP filter
may be used in case of a large DC offset present in the signal.
However, an AC signal may be used, coupled with a LP filter. AC
coupling is loosely analogous to a very low frequency HP filter. In
which case, the figures may be viewed as analogous. All of the
filtering may also all be done digitally. Stated otherwise, the
filtering and DC offset removal can be done in the digital or
analog domain. Likewise, DC offset removal, HP filtering, LP
filtering and amplification can be done in parallel or in
series.
[0074] Referring to FIGS. 11A and 11B, these figures show a blood
vessel 42 and skin section 40. Radial distension from blood
pressure is pictured in vessel 42 in FIG. 11A, and up-and-down
movement of the skin 40 in the side view of FIG. 1B.
[0075] Representative data optically captured from such movement is
shown as by data points 60 in FIG. 12 generating a 600 hemodynamic
waveform. As this data may be variously smoothed and processed into
a discrete curve (as shown in other views herein), with a first
section or a first section/domain 602 in which the heart and aorta
are in a coupled system 10 and a second section/domain 604 for the
aorta in a system 10' alone as in FIGS. 1A and 1B. These domains
are delineated (or separated) by the Dicrotic Notch (DN) as
shown.
Pulse Waveform and Embedded Frequency Acquisition
[0076] Using the subject hardware, a second set of frequencies
corresponding with the heart sounds (the "Embedded Frequencies")
are embedded within an arterial blood pressure waveform. As such,
two different types of waveform can be obtained from the same
location using the same device. Currently, tonometers for measuring
blood pressure waveforms based on pressure sensors cannot or do not
detect the Embedded Frequencies. Also, known stethoscopes (digital
or otherwise) can detect heart sound, but they cannot or do not
detect arterial blood pressure waveforms. This situation may be due
to low-pass and high-pass filtering employed in the devices as a
matter of course or design.
[0077] In any case, embodiments of the subject hardware and/or
software discard neither signal. Rather, a vibrational signal on
the skin of a patient is obtained and the signal is resolved in
into each of a pulse pressure waveform and an Embedded Frequency
signal. Doing so makes a number of techniques practical in
application, even for a patient to self-administer.
[0078] As shown in FIG. 13A, each of a hemodynamic waveform (i.e.,
pulse pressure waveform) 610 and an Embedded Frequency waveform 612
have been detected and resolved into discrete signals.
[0079] Although other filters may be used, such resolution is
preferably achieved by high-pass and/or low-pass filtering using
Fourier transforms. Low-pass filtering yields the true pulse
pressure waveform. High-pass filtering yields the true Embedded
Frequency (or heart sound). Current filtering is set with High-pass
about 20 Hz and Low-pass at about 250 Hz.
[0080] In some examples, a second derivative may be taken of the
vibrational signal for this purpose. However, Fourier transform
filtering may generally be preferred as a more accurate form of
filtering. Whereas a second derivative will tend to amplify noise,
a filter can cut it back, thus providing more accurate "character"
of a sound. In other words, use of a classical filter (such as one
based on Fourier transform) may be advantageous because it does not
artificially amplify higher frequencies thereby making it easier to
analyze a high pass signal--the Embedded Frequency in this
case.
[0081] Signals 610 and 612 were captured together as one vibration
signal detected with an optical sensor embodiment including a
membrane as discussed above. This example was generated from
measurements taken at the carotid artery (e.g., a pictured in FIG.
2) although other locations peripheral to the heart (e.g., femoral
or radial) would yield similar results.
[0082] The Embedded Frequency signals present at least three
properties. The properties open-up various opportunities of
interest.
[0083] First, it has been observed that the Embedded Frequencies
maintain the signature of the heart sound (i.e., they have the same
profile or characteristics as sound waves originating at the
heart). Accordingly, the signals can be used for cardiac
auscultation.
[0084] Second, the Embedded Frequency signals maintain a constant
distance from the beginning of the arterial blood pressure waveform
to its Dicrotic Notch (DN). In contrast, sound waves measured at
the heart travel throughout the body instantaneously making it
difficult to use heart sounds to approximate the opening and
closing of the aortic valve relative to a pressure waveform
measurement (because the pressure waveform is offset from the
instantaneous heart sound at peripheral locations). But because the
Embedded Frequency signals travels with the arterial blood pressure
waveform, they keep a unique synchronicity or timing property with
the arterial blood pressure waveform allowing for easy detection of
the DN. As such, the closing of the aortic valve (i.e., setting the
location of the DN as indicated in FIG. 13A) can possibly be
resolved even with a nondescript hemodynamic signal 620 as shown in
FIG. 13B. This can be of great benefit, especially in accurately
parsing a hemodynamic pulse pressure signal 600 into its
constituent parts 602 and 604 on either side of the DN for IF
analysis. Indeed, any cardiac cycle detection and/or segmentation
of heart waveforms is potentially aided by the use of Embedded
Frequencies. In general, timing related to arterial blood pressure
waveforms can now be accomplished using the Embedded Frequencies
instead of or in combination with arterial blood pressure
waveforms.
[0085] Third, the travel time of the Embedded Frequencies with the
pulse pressure waveform enables simplified methods of determining
Pulse Wave Velocity (PWV) and/or Systolic Time Interval (STI) as
elaborated in the Examples below.
[0086] Generally, the subject hardware and associated Embedded
Frequency methodology opens opportunities for
physiological/hemodynamic calculation and property quantification.
The ability to capture both hemodynamic waveform and Embedded
Frequency signal while eliminating the need of separate tonometer
and stethoscope hardware and/or sensing locations offers various
advantages. Moreover, the incorporation of multi-sensor technology
(e.g., by including various ECG signal acquisition options in the
sensing device or system) provides further synergy and
opportunities.
Sampling Location Optimization
[0087] As referenced above, sensor location is important for good
signal acquisition. Accordingly, a number of techniques for
identifying optimal sensor location are provided. FIGS. 14A-14C
illustrate various examples of methods (optionally, medical
methods) and software routines or techniques. As noted, these
techniques may be integrated into the UI of the subject devices
and/or accomplished through interaction with a peripheral marker,
beacon or service.
[0088] In one set of UI embodiments noted above, auditory and or
visual signal(s) for a user are assigned to information streaming
from a/the camera in the sensor device platform. As shown in FIG.
14A in more general terms, a hemodynamic signal is sensed at 700.
This signal is modified or manipulated at 702 in any of various
ways possibly described above or others, then output as a user
identified or identifiable signal at 704. Such signaling may be
auditory (e.g., as in from resolution to an intelligible signal out
of noise, as from nothing to hearing a signal, as in an accelerated
beeping to achieve a "lock," etc.) or visual (e.g., as indicated by
light blinking or intensity, as gauged by a meter, etc.) as
described above or otherwise. As the user moves the sensor device
the process continues as indicated by the loop line until the user
is directed by device feedback to a location where adequate signal
is obtained and the process ends at 706.
[0089] In another set of UI embodiments, a method may be carried
out in connection with a locator system as illustrated in FIG. 14B.
In which case, sensing may begin at one position at 700. Using
directional microphones or other techniques, this position can be
related to more optimal position at 708 and then the user directed
accordingly (such as by above or otherwise) at 704 as he or she
moves towards or away from a more optimal position for sensing. As
indicated, repeated signaling and sensing may be required. When an
adequate signal is sensed and recorded, the process may end at
706.
[0090] In yet another set of UI embodiments, locating the sensor
device for optimal signal acquisition may be achieved in connection
with a constant marker as illustrated in FIG. 14C. In which case,
the system may identify the marker (i.e., not usually viable to the
user as discussed above) at 710. Then via various user-identified
signal options (per above or otherwise) direct the user to the
marker location at 712. Upon achieving desired location, sensing
may then occur at 700 after which the process ends at 706. If
optimal placement has not been achieved, however, or if multiple
nearby sampling points are desired then the method may be run
repeatedly or recursively with either goal in mind (i.e., for more
accurate home-in to the marker and/or scattered sampling adjacent
the marker point).
Examples
[0091] The subject systems have been discussed above as capable of
delivering hemodynamic waveform data optically by acquisition with
a smartphone in connection with its LED flash element and an LED
phototransistor pair. Such data may be smoothed or averaged in
connection with a graphical UI.
[0092] With reference to FIG. 4B, a carotid pressure waveform 800
is shown as recorded using an IPHONE camera and LED per above
(although FIGS. 4A and 4B illustrate another smartphone hardware
option). On display 320, a complete cardiac cycle 802 has been
marked by three colored circular markers in the following sequence:
red 804, white 806 and blue 808 (whereas this particular color
scheme was created to cause the user to infer a
particular--familiar--order as red being first, white second and
blue third.) In this case, the time duration between the red and
blue markers is the period of the cardiac cycle.
[0093] Display 320 also shows a Heart Rate (HR) of 60.03 bpm and
.omega..sub.1=100 and .omega..sub.2=50.4 calculated using a/the
Cloud 210 computing service. Then utilizing the approach described
in U.S. patent application Ser. No. 14/517,702, ejection fraction
for the exemplary measurements was produced yielding a result of
68%. This result offered good agreement with an ejection fraction
of 64% for the same patient as measured by a biplane echo. In
another example, .omega..sub.1 and .omega..sub.2, were calculated
(also using a/the Cloud service) as 93.63 and 29.6, respectively,
with a HR of 94.84 as shown in FIG. 3.
[0094] In each example (but described further in reference to FIG.
4B), the individual color-coded points in the waveform(s) can be
selected using a combination of the markers and the "plus" and
"minus" buttons 810. In one embodiment, a finger tap selection on
the graph frame displaying the waveform auto-locates the markers
based on the marker selected and the location of the tap relative
to the graph frame. In another embodiment, the points are advanced
into position using a slider. In another embodiment, the markers on
the waveform can be dragged from sample to sample. In yet another
embodiment, gestures or voice commands may be used to increment the
markers in either direction. The markers can be stepped through the
points on the waveform my clicking the plus and minus buttons. This
sequence corresponds to the start, Dicrotic Notch (DN) as well as
the end of a complete cardiac cycle and are the three inputs in
addition to the data required by the intrinsic frequency
algorithm.
[0095] These features are important to delivering a feel of control
to the user given limited screen size of portable devices and the
size of a finger or handheld stylus, particularly when high
sampling rates are used. Since picking the points can affect the
diagnostic outcome this UI control is a required feature.
Additionally, this UI feature allows a balance between accurate
point selection of the cardiac cycle while allowing the user a
visual reference to larger features of the waveform. Also, the
ability to manually confirm or select points can avoid any
automatic selection that errors in selecting the DN, which can be
difficult with previously known techniques.
[0096] However, an example herein provides a reliable means of
determining the DN position or location within the subject
hemodynamic waveform data. Namely, with data acquired from systems
capable of detecting and/or filtering for an Embedded Frequency
signal, as seen in FIG. 13A, it has been observed that the portion
Embedded Frequency 612 created during the closing of the aortic
valve remains a time interval ("t") approximately 40 milliseconds
behind the Dicrotic Notch (DN) of the blood pressure waveform 610.
In practice, the exact amount of delay or the exact feature of the
S2 that we look at depends on the filter itself. Generally, there
is a delay (e.g., about 4 to about 40 milliseconds) behind the
notch. This slight delay will be dependent (but consistent) on the
filter qualities. As such, the Embedded Frequency provides a
computationally efficient and reliable indication of where the DN
of the blood pressure waveform is located.
[0097] In another example, the subject hardware can be used for
determining Pressure Wave Velocity (PVW). In which case, the
hardware will include ECG sensor contact or lead electrodes. To
make the determination, an ECG and the heart sound is recorded
a/the location of the heart and then ECG is measured again while
the Embedded Frequency (heart sound) is recorded at a peripheral
location (e.g., the carotid artery). By measuring distance between
the location of the heart and the location of the subject device
and the time it takes for the Embedded Frequency signal to travel
from the heart to the selected peripheral location artery (timing
each off of the ECG signal which is travels through the body
instantaneously), then the speed at which the blood pressure wave
travelled can me mathematically determined.
[0098] In another example, the subject hardware can again be used
for determining Pressure Wave Velocity (PVW). In which case, the
hardware will include an external microphone. To make the PWV
determination, first the heart sound is recorded a/the location of
the heart while, simultaneously, the Embedded Frequency (heart
sound) is recorded at one peripheral location (e.g., the carotid
artery) using the subject hardware. Then, the heart sound is
recorded a/the location of the heart while, simultaneously, the
Embedded Frequency (heart sound) is recorded at a different one
peripheral location (e.g., the femoral artery) using the subject
hardware. By measuring the distance between the two peripheral
locations and the time it takes for the Embedded Frequency signal
to travel from the heart to the selected peripheral locations
(timing each off of the heart sound recorded at the location of the
heart), then the speed at which the blood pressure wave travelled
can me mathematically determined to measure, for instance,
carotid-femoral or carotid-brachial pulse wave velocity.
Alternatively, to measure ascending or descending aortic pulse wave
velocity, first the heart sound is recorded a/the location of the
heart while, simultaneously, the Embedded Frequency (heart sound)
is recorded at one peripheral location (e.g., the carotid,
brachial, radial or femoral artery) using the subject hardware. By
calculating the distance between the heart and the peripheral
location where the measurement is taken one can mathematically
determine ascending or descending aortic pulse wave velocity.
[0099] The subject hardware may also be used in connection with
Embedded Frequency signal detection to provide a new approach to
measuring systolic time intervals. Systolic time intervals have
been measured using ECG, phonocardiogram and arterial blood
pressure waveforms. In the past, three different devices at three
different locations were used for this purpose. Using Embedded
Frequencies according to the teachings herein, it is now possible
to take measurements for calculating systolic time intervals with a
single device and/or in a single location. In the subject
technique, the sound waves used in prior systolic time interval
calculations (e.g., Circulation, 1968; 37, 150) are replaced by the
Embedded Frequencies measured. In which case, as indicated in FIG.
13C:
PEP=QS.sub.2-LVET (1)
ICT=S.sub.1S.sub.2-LVET (2)
Q-1=QS.sub.2-S.sub.1S.sub.2 (3)
where QS.sub.2 is the total electromechanical systole,
S.sub.1S.sub.2 is the hear sounds interval (in this case found by
Embedded Frequency signal measurement), LVET is left ventricular
ejection time, PEP is total electromechanical systole, Q-1 is the
interval from onset of QRS to the first heart sound, and ICT is
isovolumic contraction time.
[0100] In another example, Ejection Fraction is determined using
PEP as calculated above and the following equation adapted from
Circulation, 1970; 42: 457:
EF=1.125-1.25 PEP/LVET (4)
where EF is ejection fraction and the PEP and LVET parameters are
defined above. As such, EF is efficiently and accurately calculated
on a basis including the subject Embedded Frequency signal
acquisition systems and methods.
Variations
[0101] In addition to the embodiments that been disclosed in detail
above, still more are possible within the classes described and the
inventors intend these to be encompassed within this Specification
and claims. This disclosure is intended to be exemplary, and the
claims are intended to cover any modification or alternative which
might be predictable to a person having ordinary skill in the
art.
[0102] Moreover, the various illustrative processes described in
connection with the embodiments herein may be implemented or
performed with a general purpose processor, a Digital Signal
Processor (DSP), an Application Specific Integrated Circuit (ASIC),
a Field Programmable Gate Array (FPGA) or other programmable logic
device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general purpose processor may be a
microprocessor, but in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state
machine. The processor can be part of a computer system that also
has a user interface port that communicates with a user interface,
and which receives commands entered by a user, has at least one
memory (e.g., hard drive or other comparable storage, and random
access memory) that stores electronic information including a
program that operates under control of the processor and with
communication via the user interface port, and a video output that
produces its output via any kind of video output format, e.g., VGA,
DVI, HDMI, DisplayPort, or any other form.
[0103] A processor may also be implemented as a combination of
computing devices, e.g., a combination of a DSP and a
microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration. These devices may also be used to select values for
devices as described herein. The camera may be a digital camera of
any type including those using CMOS, CCD or other digital image
capture technology.
[0104] The steps of a method or algorithm described in connection
with the embodiments disclosed herein may be embodied directly in
hardware, in a software module executed by a processor, or in a
combination of the two. A software module may reside in Random
Access Memory (RAM), flash memory, Read Only Memory (ROM),
Electrically Programmable ROM (EPROM), Electrically Erasable
Programmable ROM (EEPROM), registers, hard disk, a removable disk,
a CD-ROM, or any other form of storage medium known in the art. An
exemplary storage medium is coupled to the processor such that the
processor can read information from, and write information to, the
storage medium. In the alternative, the storage medium may be
integral to the processor. The processor and the storage medium may
reside in an ASIC. The ASIC may reside in a user terminal. In the
alternative, the processor and the storage medium may reside as
discrete components in a user terminal.
[0105] In one or more exemplary embodiments, the functions
described may be implemented in hardware, software, firmware, or
any combination thereof. If implemented in software, the functions
may be stored on, transmitted over or resulting
analysis/calculation data output as one or more instructions, code
or other information on a computer-readable medium.
Computer-readable media includes both computer storage media and
communication media including any medium that facilitates transfer
of a computer program from one place to another. A storage media
may be any available non-transitory media that can be accessed by a
computer. By way of example, and not limitation, such
computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or
other optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium that can be used to carry or
store desired program code in the form of instructions or data
structures and that can be accessed by a computer. The memory
storage can also be rotating magnetic hard disk drives, optical
disk drives, or flash memory based storage drives or other such
solid state, magnetic, or optical storage devices. Disk and disc,
as used herein, includes compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and Blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media.
[0106] All embodiments disclosed herein are intended for use with
memory, storage, and/or computer readable media that is
non-transitory. Accordingly, to the extent that memory, storage,
and/or computer readable media are covered by one or more claims,
then that memory, storage, and/or computer readable media is only
non-transitory.
[0107] Operations as described herein can be carried out on or over
a website. The website can be operated on a server computer or
operated locally, e.g., by being downloaded to the client computer,
or operated via a server farm. The website can be accessed over a
mobile phone or a PDA, or on any other client. The website can use
HTML code in any form, e.g., MHTML, or XML, and via any form such
as cascading style sheets ("CSS") or other.
[0108] Also, the inventors intend that only those claims which use
the words "means for" are intended to be interpreted under 35 USC
112(f). Moreover, no limitations from the specification are
intended to be read into any claims, unless those limitations are
expressly included in the claims. The computers described herein
may be any kind of computer, either general purpose, or some
specific purpose computer such as a workstation. The programs may
be written in C, or Java, Brew or any other programming language.
The programs may be resident on a storage medium, e.g., magnetic or
optical, e.g. the computer hard drive, a removable disk or media
such as a memory stick or SD media, or other removable medium. The
programs may also be run over a network, for example, with a server
or other machine sending signals to the local machine, which allows
the local machine to carry out the operations described herein.
[0109] Also, it is contemplated that any optional feature of the
embodiment variations described may be set forth and claimed
independently, or in combination with any one or more of the
features described herein. Reference to a singular item, includes
the possibility that there is a plurality of the same items
present. More specifically, as used herein and in the appended
claims, the singular forms "a," "an," "said," and "the" include
plural referents unless specifically stated otherwise. In other
words, use of the articles allow for "at least one" of the subject
item in the description above as well as the claims below. It is
further noted that the claims may be drafted to exclude any
optional element. As such, this statement is intended to serve as
antecedent basis for use of such exclusive terminology as "solely,"
"only" and the like in connection with the recitation of claim
elements, or use of a "negative" limitation.
[0110] Without the use of such exclusive terminology, the term
"comprising" in the claims shall allow for the inclusion of any
additional element irrespective of whether a given number of
elements are enumerated in the claim, or the addition of a feature
could be regarded as transforming the nature of an element set
forth in the claims. Except as specifically defined herein, all
technical and scientific terms used herein are to be given as broad
a commonly understood meaning as possible while maintaining claim
validity.
* * * * *