U.S. patent application number 11/561428 was filed with the patent office on 2008-05-22 for respiration-synchronized heart sound trending.
This patent application is currently assigned to Cardiac Pacemakers, Inc.. Invention is credited to Gerrard M. Carlson, Carlos Haro, Abhilash Patangay, Yi Zhang.
Application Number | 20080119749 11/561428 |
Document ID | / |
Family ID | 39402886 |
Filed Date | 2008-05-22 |
United States Patent
Application |
20080119749 |
Kind Code |
A1 |
Haro; Carlos ; et
al. |
May 22, 2008 |
RESPIRATION-SYNCHRONIZED HEART SOUND TRENDING
Abstract
Respiration-synchronized heart sound trends can be detected
using an implantable medical device, including a respiration
sensor, a respiration phase detector, a heart sound sensor, a heart
sound detector, and a processor. The implantable medical device can
also include a cardiac sensor. The respiration-synchronized heart
sound trends can include heart sounds occurring during specific
phases of a respiration signal, such as inspiration or expiration.
The heart sound signal can be gated or the heart sound sensor can
be enabled or disabled using the cardiac sensor or the respiration
sensor. Further, the heart sound trends can be displayed using an
external display, and can provide information about a
cardiovascular status using an analysis module, or the analysis
module and a blood volume sensor.
Inventors: |
Haro; Carlos; (St. Paul,
MN) ; Zhang; Yi; (Blaine, MN) ; Patangay;
Abhilash; (Little Canada, MN) ; Carlson; Gerrard
M.; (Champlin, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Cardiac Pacemakers, Inc.
North St. Paul
MN
|
Family ID: |
39402886 |
Appl. No.: |
11/561428 |
Filed: |
November 20, 2006 |
Current U.S.
Class: |
600/528 |
Current CPC
Class: |
A61B 5/0816 20130101;
A61B 7/04 20130101; A61B 5/0205 20130101; A61B 5/0031 20130101;
A61B 5/318 20210101; G16H 40/63 20180101; A61B 5/103 20130101; A61B
5/053 20130101; A61N 1/36578 20130101; A61B 5/025 20130101; A61B
5/0295 20130101; A61B 7/00 20130101; A61N 1/36542 20130101; A61N
1/36521 20130101; A61B 5/029 20130101 |
Class at
Publication: |
600/528 |
International
Class: |
A61B 5/02 20060101
A61B005/02 |
Claims
1. A system comprising: an implantable medical device, including: a
respiration sensor, configured to sense a respiration signal; and a
heart sound sensor, configured to sense a heart sound signal; an
implantable or external respiration phase detector, coupled to the
respiration sensor, configured to detect at least one phase of the
respiration signal; an implantable or external heart sound
detector, coupled to the heart sound sensor, configured to detect
at least one heart sound of the heart sound signal; and an
implantable or external processor, coupled to the respiration phase
detector and the heart sound detector, wherein the processor is
configured to automatically produce at least one heart sound trend
over at least a portion of at least one respiration cycle using the
at least one heart sound, the at least one heart sound trend
occurring during a specified at least a portion of at least one
phase of the respiration signal.
2. The system of claim 1, wherein the at least one heart sound
trend includes at least one measurement, feature, characteristic,
computation, or interval of at least one heart sound.
3. The system of claim 2, wherein the at least one measurement,
feature, characteristic, computation, or interval of at least one
heart sound includes at least one of an amplitude of a heart sound,
a time interval between a first heart sound and a second heart
sound, an energy of a heart sound, and a normalized measurement,
feature, characteristic, computation, or interval of the heart
sound signal by another measurement, feature, characteristic,
computation, or interval of the heart sound signal.
4. The system of claim 1, wherein the implantable medical device
includes: a cardiac sensor, coupled to the heart sound detector,
configured to sense a cardiac signal; and wherein the heart sound
detector is configured to detect at least one heart sound of the
heart sound signal using information from the cardiac signal.
5. The system of claim 4, wherein the at least one heart sound
includes at least one measurement, feature, characteristic,
computation, or interval between at least one cardiac signal
feature and at least one heart sound feature.
6. The system of claim 4, including an implantable or external
gating circuit, coupled to the cardiac sensor and the heart sound
detector, wherein the gating circuit is configured to obtain a
gated heart sound signal by gating the heart sound signal using
information from the cardiac signal, and wherein the heart sound
detector is configured to detect at least one heart sound of the
gated heart sound signal.
7. The system of claim 4, wherein the heart sound sensor is coupled
to the cardiac sensor, wherein the heart sound sensor is enabled or
disabled using information from the cardiac signal.
8. The system of claim 1, wherein the heart sound sensor is coupled
to the respiration sensor, wherein the heart sound sensor is
enabled or disabled using information from the respiration
signal.
9. The system of claim 1, wherein the heart sound sensor is coupled
to the respiration phase detector, wherein the heart sound sensor
is enabled during the specified at least a portion of at least one
phase of the respiration signal.
10. The system of claim 1, including an implantable or external
gating circuit, coupled to the respiration phase detector and the
heart sound detector, wherein the gating circuit is configured to
obtain a gated heart sound signal by gating the heart sound signal
using information from the respiration phase detector, and wherein
the heart sound detector is configured to detect at least one heart
sound of the gated heart sound signal.
11. The system of claim 1, including an external display, coupled
to the processor, wherein the display is configured to display
information from the processor.
12. The system of claim 1, including an implantable or external
analysis module, coupled to the processor, wherein the analysis
module is configured to provide information about at least one
cardiovascular status using information from the at least one heart
sound trend.
13. The system of claim 12, wherein the analysis module is
configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend occurring during at least a portion of the at least one
specified phase of the respiration signal.
14. The system of claim 12, wherein the implantable medical device
includes an implantable blood volume sensor, coupled to the
processor, wherein the blood volume sensor is configured to detect
information about a blood volume.
15. The system of claim 14, wherein the analysis module is
configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend and the blood volume sensor.
16. The system of claim 15, wherein the analysis module is
configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend occurring during at least a portion of at least one
specified phase of the respiration signal and using information
from the blood volume sensor.
17. A system comprising: means for sensing a respiration signal
within a body; means for detecting at least one phase of the
respiration signal; means for sensing a heart sound signal within
the body; means for detecting at least one heart sound of the heart
sound signal; and means for automatically producing at least one
heart sound trend, over at least a portion of at least one
respiration cycle, wherein the at least one heart sound trend is
indicative of at least one heart sound occurring during a specified
at least a portion of at least one phase of the respiration
signal.
18. A method comprising: sensing a respiration signal using an
implanted respiration sensor; detecting at least one phase of the
respiration signal; sensing a heart sound signal using an implanted
heart sound sensor; detecting at least one heart sound of the heart
sound signal; and automatically producing at least one heart sound
trend, over at least a portion of at least one respiration cycle,
wherein the at least one heart sound trend is indicative of at
least one heart sound occurring during a specified at least a
portion of at least one phase of the respiration signal.
19. The method of claim 18, wherein automatically producing the at
least one heart sound trend includes automatically producing at
least one measurement, feature, characteristic, computation, or
interval of at least one heart sound.
20. The method of claim 19, wherein automatically producing at
least one measurement, feature, characteristic, computation, or
interval of at least one heart sound includes at least one of an
automatically producing an amplitude of a heart sound,
automatically producing a time interval between a first heart sound
and a second heart sound, automatically producing an energy of a
heart sound, and automatically producing a normalized measurement,
feature, characteristic, computation, or interval of the heart
sound signal by another measurement, feature, characteristic,
computation, or interval of the heart sound signal.
21. The method of claim 18, including: sensing a cardiac signal
using an implanted cardiac sensor; and wherein the detecting at
least one heart sound includes using information from the cardiac
signal.
22. The method of claim 21, wherein the automatically producing at
least one heart sound trend includes automatically producing at
least one measurement, feature, characteristic, computation, or
interval between at least one cardiac signal feature and at least
one heart sound feature.
23. The method of claim 21, including gating the heart sound signal
using a gating circuit to detect at least one heart sound, wherein
the gating the heart sound signal includes using information from
the cardiac signal.
24. The method of claim 21, including enabling or disabling the
heart sound sensor using information from the cardiac signal.
25. The method of claim 18, including enabling or disabling the
heart sound sensor using information from the respiration
signal.
26. The method of claim 18, including enabling the heart sound
sensor during at least one of the specified at least a portion of
at least one phase of the respiration signal.
27. The method of claim 18, including gating the heart sound signal
to detect at least one heart sound, wherein the gating the heart
sound signal includes gating the heart sound signal using
information from the respiration signal.
28. The method of claim 18, including displaying the at least one
heart sound trend.
29. The method of claim 18, including providing information about
at least one cardiovascular status using information from the at
least one heart sound trend.
30. The method of claim 29, wherein providing information about at
least one cardiovascular status includes using information from the
at least one heart sound trend occurring during specified different
first and second phases of the respiration signal.
31. The method of claim 29, including detecting information about a
blood volume using an implanted blood volume sensor.
32. The method of claim 31, wherein providing information about the
at least one cardiovascular status includes using information from
the at least one heart sound trend and using information about the
blood volume.
33. The method of claim 32, wherein providing information about the
at least one cardiovascular status includes using information from
the at least one heart sound trend occurring during specified
different first and second phases of the respiration signal and
using information about the blood volume.
Description
TECHNICAL FIELD
[0001] This patent document pertains generally to cardiac health,
and more particularly, but not by way of limitation, to
respiration-synchronized heart sound trending.
BACKGROUND
[0002] The heart is the center of the circulatory system of the
human body. The left-sided chambers of the heart, including the
left atrium and the left ventricle, draw oxygenated blood from the
lungs and pump it to the organs of the body to provide the organs
with oxygen. The right-sided chambers of the heart, including the
right atrium and the right ventricle, draw deoxygenated blood from
the organs and pump it into the lungs where the blood gets
oxygenated.
[0003] The lungs are the center of the respiratory system of the
human body. Respiration generally includes inhalation and
exhalation. Inhalation is the act of bringing air into the lungs.
As the diaphragm contracts, the airspace volume of the thorax
increases, resulting in a decreased intrathoracic pressure. The
decreased intrathoracic pressure draws air into the lungs. As the
diaphragm relaxes, the airspace volume of the thorax decreases. The
resulting increased intrathoracic pressure forces excess air out of
the lungs.
[0004] Aerobic respiration, the process of energy production in the
human body, typically requires oxygen as fuel and produces carbon
dioxide as a by-product. The respiratory system generally draws
oxygen into the body and expels carbon-dioxide into the atmosphere.
During inhalation, oxygen-rich air is brought into the lungs, where
the oxygen is diffused into the blood. During exhalation, carbon
dioxide is released from the blood into the atmosphere.
[0005] Typically, as the human body requires more oxygen for energy
production, cardiac activity increases. Thus, because cardiac
performance typically varies depending on the state of respiration,
a relationship exists between the cardiovascular and respiratory
systems of the body.
OVERVIEW
[0006] This summary is intended to provide an overview of the
subject matter of the present patent application. It is not
intended to provide an exclusive or exhaustive explanation of the
invention. The detailed description is included to provide further
information about the subject matter of the present patent
application.
[0007] In Example 1, a system includes an implantable medical
device. The implantable medical device includes a respiration
sensor, configured to sense a respiration signal. The implantable
medical device also includes a heart sound sensor, configured to
sense a heart sound signal. The system also includes an implantable
or external respiration phase detector, coupled to the respiration
sensor, configured to detect at least one phase of the respiration
signal. The system also includes an implantable or external heart
sound detector, coupled to the heart sound sensor, configured to
detect at least one heart sound of the heart sound signal. The
system also includes an implantable or external processor, coupled
to the respiration phase detector and the heart sound detector,
wherein the processor is configured to automatically produce at
least one heart sound trend over at least a portion of at least one
respiration cycle using the at least one heart sound, the at least
one heart sound trend occurring during a specified at least a
portion of at least one phase of the respiration signal.
[0008] In Example 2, the at least one heart sound trend of Example
1 optionally includes at least one measurement, feature,
characteristic, computation, or interval of at least one heart
sound.
[0009] In Example 3, the at least one measurement, feature,
characteristic, computation, or interval of at least one heart
sound of Examples 1-2 optionally includes at least one of an
amplitude of a heart sound, a time interval between a first heart
sound and a second heart sound, and a normalized amplitude or
interval of at least one measurement, feature, or characteristic of
the heart sound signal.
[0010] In Example 4, the implantable medical device of Examples 1-3
optionally includes a cardiac sensor, coupled to the heart sound
detector, configured to sense a cardiac signal. The heart sound
detector of Examples 1-3 is also optionally configured to detect at
least one heart sound of the heart sound signal using information
from the cardiac signal.
[0011] In Example 5, the at least one heart sound of Examples 1-4
optionally includes at least one measurement, feature,
characteristic, computation, or interval between at least one
cardiac signal feature and at least one heart sound feature.
[0012] In Example 6, the system of Examples 1-5 optionally includes
an implantable or external gating circuit, coupled to the cardiac
sensor and the heart sound detector, wherein the gating circuit is
configured to obtain a gated heart sound signal by gating the heart
sound signal using information from the cardiac signal, and wherein
the heart sound detector is configured to detect at least one heart
sound of the gated heart sound signal.
[0013] In Example 7, the heart sound sensor of Examples 1-6 is
optionally coupled to the cardiac sensor, wherein the heart sound
sensor is enabled and disabled using the at least one cardiac
signal feature.
[0014] In Example 8, the heart sound sensor of Examples 1-7 is
optionally coupled to the respiration phase detector, wherein the
heart sound sensor is enabled during the specified at least a
portion of at least one phase of the respiration signal.
[0015] In Example 9, the system of Examples 1-8 optionally includes
an implantable or external gating circuit, coupled to the
respiration phase detector and the heart sound detector, wherein
the gating circuit is configured to obtain a gated heart sound
signal by gating the heart sound signal using information from the
respiration phase detector, and wherein the heart sound detector is
configured to detect at least one heart sound of the gated heart
sound signal.
[0016] In Example 10, the system of Examples 1-9 optionally
includes an external display, coupled to the processor, wherein the
display is configured to display information from the
processor.
[0017] In Example 11, the system of Examples 1-10 optionally
includes an implantable or external analysis module, coupled to the
processor, wherein the analysis module is configured to provide
information about at least one cardiovascular status using
information from the at least one heart sound trend.
[0018] In Example 12, the analysis module of Examples 1-11 is
optionally configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend occurring during at least a portion of the at least one
specified phase of the respiration signal.
[0019] In Example 13, the implantable medical device of Examples
1-12 optionally includes an implantable blood volume sensor,
coupled to the processor, wherein the blood volume sensor is
configured to detect information about a blood volume.
[0020] In Example 14, the analysis module of Examples 1-13 is
optionally configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend and the blood volume sensor.
[0021] In Example 15, the analysis module of Examples 1-14 is
optionally configured to provide information about the at least one
cardiovascular status using information from the at least one heart
sound trend occurring during at least a portion of at least one
specified phase of the respiration signal and using information
from the blood volume sensor.
[0022] In Example 16, a system includes means for sensing a
respiration signal within a body, such as by using a respiration
sensor to sense a respiration signal. The system also includes
means for detecting at least one phase of the respiration signal,
such as by using a respiration phase detector to detect at least
one phase of the respiration signal. The system also includes means
for sensing a heart sound signal within the body, such as by using
a heart sound sensor to sense a heart sound signal. The system also
includes means for detecting at least one heart sound of the heart
sound signal, such as by using a heart sound detector to detect at
least one heart sound of the heart sound signal. The system also
includes means for automatically producing at least one heart sound
trend, over at least a portion of at least one respiration cycle,
wherein the at least one heart sound trend is indicative of at
least one heart sound occurring during a specified at least a
portion of at least one phase of the respiration signal, such as by
using a processor, wherein the processor is configured to
automatically produce at least one heart sound trend over at least
a portion of at least one respiration cycle using the at least one
heart sound, the at least one heart sound trend occurring during a
specified at least a portion of at least one phase of the
respiration signal.
[0023] In Example 17, a method includes sensing a respiration
signal using an implanted respiration sensor. The method also
includes detecting at least one phase of the respiration signal.
The method also includes sensing a heart sound signal using an
implanted heart sound sensor. The method also includes detecting at
least one heart sound of the heart sound signal. The method also
includes automatically producing at least one heart sound trend,
over at least a portion of at least one respiration cycle, wherein
the at least one heart sound trend is indicative of at least one
heart sound occurring during a specified at least a portion of at
least one phase of the respiration signal.
[0024] In Example 18, the automatically producing the at least one
heart sound trend of Example 17 optionally includes automatically
producing at least one measurement, feature, characteristic,
computation, or interval of at least one heart sound.
[0025] In Example 19, the automatically producing at least one
measurement, feature, characteristic, computation, or interval of
at least one heart sound of Examples 17-18 optionally includes at
least one of an automatically producing an amplitude of a heart
sound, automatically producing a time interval between a first
heart sound and a second heart sound, and automatically producing a
normalized amplitude or interval of at least one measurement,
feature, or characteristic of the heart sound signal.
[0026] In Example 20, the method of Examples 17-19 optionally
includes sensing a cardiac signal using an implanted cardiac
sensor. The detecting at least one heart sound of Examples 17-19
also optionally includes using information from the cardiac
signal.
[0027] In Example 21, the automatically producing at least one
heart sound trend of Examples 17-20 optionally includes
automatically producing at least one measurement, feature,
characteristic, computation, or interval between at least one
cardiac signal feature and at least one heart sound feature.
[0028] In Example 22, the method of Examples 17-21 optionally
includes gating the heart sound signal using a gating circuit to
detect at least one heart sound, wherein the gating the heart sound
signal includes using information from the cardiac signal.
[0029] In Example 23, the method of Examples 17-22 optionally
includes enabling and disabling the heart sound sensor using the at
least one cardiac signal feature.
[0030] In Example 24, the method of Examples 17-23 optionally
includes enabling the heart sound sensor during at least one of the
specified at least a portion of at least one phase of the
respiration signal.
[0031] In Example 25, the method of Examples 17-24 optionally
includes gating the heart sound signal to detect at least one heart
sound, wherein the gating the heart sound signal includes gating
the heart sound signal using information from the respiration
signal.
[0032] In Example 26, the method of Examples 17-25 optionally
includes displaying the at least one heart sound trend.
[0033] In Example 27, the method of Examples 17-26 optionally
includes providing information about at least one cardiovascular
status using information from the at least one heart sound
trend.
[0034] In Example 28, the providing information about at least one
cardiovascular status of Examples 17-27 optionally includes using
information from the at least one heart sound trend occurring
during specified different first and second phases of the
respiration signal.
[0035] In Example 29, the method of Examples 17-28 optionally
includes detecting information about a blood volume using an
implanted blood volume sensor.
[0036] In Example 30, the providing information about the at least
one cardiovascular status of Examples 17-29 optionally includes
using information from the at least one heart sound trend and using
information about the blood volume.
[0037] In Example 31, the providing information about the at least
one cardiovascular status of Examples 17-30 optionally includes
using information from the at least one heart sound trend occurring
during specified different first and second phases of the
respiration signal and using information about the blood
volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In the drawings, which are not necessarily drawn to scale,
like numerals describe substantially similar components throughout
the several views. Like numerals having different letter suffixes
represent different instances of substantially similar components.
The drawings illustrate generally, by way of example, but not by
way of limitation, various embodiments discussed in the present
document.
[0039] FIG. 1 illustrates generally an example of a system
including an implantable medical device, which includes a
respiration sensor, a respiration phase detector, a heart sound
sensor, a heart sound detector, and a processor.
[0040] FIG. 2 illustrates generally an example of portions of a
system including a heart sound detector and a cardiac sensor.
[0041] FIG. 3 illustrates generally an example of portions of a
system including a heart sound detector, a gating circuit, and a
cardiac sensor.
[0042] FIG. 4 illustrates generally an example of portions of a
system including a heart sound sensor and a cardiac sensor.
[0043] FIG. 5 illustrates generally an example of portions of a
system including a respiration phase detector and a heart sound
sensor.
[0044] FIG. 6 illustrates generally an example of portions of a
system including a respiration phase detector, a gating circuit,
and a heart sound detector.
[0045] FIG. 7 illustrates generally an example of portions of a
system including a processor and an external display.
[0046] FIG. 8 illustrates generally an example of portions of a
system including a processor and an analysis module.
[0047] FIG. 9 illustrates generally an example of portions of a
system including a processor, an analysis module, and a blood
volume sensor.
[0048] FIG. 10 illustrates generally an example of a relationship
between a respiration signal and a heart sound signal.
[0049] FIG. 11 illustrates generally an example of a relationship
between the amplitude of a first heart sound ("S1 amplitude") and
the rate of pressure change ("dP/dt"), including a regression line
and a correlation value ("R.sup.2").
[0050] FIG. 12 illustrates generally an example of a relationship
between the amplitude of a first heart sound ("S1 amplitude") and
the rate of pressure change ("dP/dt"), including an inspiratory
first heart sound amplitude ("inspiratory S1 amplitude") versus
dP/dt, an inspiratory regression line, an inspiratory correlation
value ("inspiratory R 2"), an expiratory first heart sound
amplitude ("expiratory S1 amplitude") versus dP/dt, an expiratory
regression line, and an expiratory correlation value ("expiratory
R.sup.2").
[0051] FIG. 13 illustrates generally an example of a relationship
between a first heart sound ("S1") and a blood volume.
[0052] FIG. 14 illustrates generally an example of a method
including sensing a respiration signal, detecting at least one
phase of a respiration signal, sensing a heart sound signal,
detecting at least one heart sound, and automatically producing at
least one heart sound trend.
[0053] FIG. 15 illustrates generally an example of portions of a
method including sensing a heart sound signal, sensing a cardiac
signal, and detecting at least one heart sound.
[0054] FIG. 16 illustrates generally an example of portions of
method including sensing a heart sound signal, sensing a cardiac
signal, and gating the heart sound signal.
[0055] FIG. 17 illustrates generally an example of portions of a
method including sensing a cardiac signal and enabling or disabling
the heart sound sensor.
[0056] FIG. 18 illustrates generally an example of portions of a
method including detecting at least one phase of a respiration
signal and enabling or disabling the heart sound sensor.
[0057] FIG. 19 illustrates generally an example of portions of a
method including sensing a heart sound signal, sensing a
respiration signal, and gating the heart sound signal.
[0058] FIG. 20 illustrates generally an example of portions of a
method including automatically producing at least one heart sound
trend and displaying the at least one heart sound trend.
[0059] FIG. 21 illustrates generally an example of portions of a
method including automatically producing at least one heart sound
trend and providing information about at least one cardiovascular
status.
[0060] FIG. 22 illustrates generally an example of portions of a
method including automatically producing at least one heart sound
trend, detecting information about a blood volume, and providing
information about at least one cardiovascular status.
DETAILED DESCRIPTION
[0061] The following detailed description includes references to
the accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention may be practiced. These
embodiments, which are also referred to herein as "examples," are
described in enough detail to enable those skilled in the art to
practice the invention. The embodiments may be combined, other
embodiments may be utilized, or structural, logical and electrical
changes may be made without departing from the scope of the present
invention. The following detailed description is, therefore, not to
be taken in a limiting sense, and the scope of the present
invention is defined by the appended claims and their
equivalents.
[0062] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one. In
this document, the term "or" is used to refer to a nonexclusive or,
unless otherwise indicated. The term "heart sound" is used to refer
to the heart sound of a subject, and can include a first heart
sound ("S1"), a second heart sound ("S2"), a third heart sound
("S3"), a fourth heart sound ("S4"), or any components thereof,
such as the aortic component of S2 ("A2"), the pulmonic component
of S2 ("P2"), or other sounds or vibrations associated with valve
closures or fluid movement, such as a heart murmur, etc. Also, in
this document, the terms "fist heart sound", "second heart sound",
etc. are used to label a heart sound occurring in time, unless
otherwise indicated, such as a first heart sound ("S1"), second
heart sound ("S2"), etc. Furthermore, all publications, patents,
and patent documents referred to in this document are incorporated
by reference herein in their entirety, as though individually
incorporated by reference. In the event of inconsistent usages
between this document and those documents so incorporated by
reference, the usage in the incorporated reference(s) should be
considered supplementary to that of this document; for
irreconcilable inconsistencies, the usage in this document
controls.
[0063] Generally, inspiration results in a decreased intrathoracic
pressure. The decreased intrathoracic pressure typically causes an
increase in the venous blood return to the right side of the heart.
The increased volume of blood entering the right-sided chambers of
the heart can restrict the amount of blood entering the left-sided
chambers of the heart. Typically, expiration results in an
increased intrathoracic pressure. The increased intrathoracic
pressure typically causes a decrease in the venous blood return to
the right side of the heart. The decreased volume of blood entering
the right-sided chambers of the heart can increase the amount of
blood entering the left-sided chambers of the heart.
[0064] Detection of heart sounds during a particular phase or
portion of the respiration cycle can result in an improved signal
to noise ratio or correlation of the heart sound signal, generally
due to the reduction in variability of the heart sound normally
caused by respiration. An example of an improved correlation can be
seen from FIG. 11 to FIG. 12. Further, noise from respiratory
events, such as apnea, can be eliminated to improve certain
diagnostic capabilities, such as heart failure diagnostics.
[0065] The detection of heart sounds during a particular phase or
portion of the respiration cycle can also be used to obtain useful
information, such as a slope of the Frank-Starling curve (the rate
of change of at least one measurement, feature, characteristic,
computation, or interval of at least a portion of at least one
heart sound over the rate of change of blood volume), a comparison
of heart sounds obtained during inspiration and expiration, etc.
Such diagnostic information can be used to determine information
about at least one cardiovascular status, including heart failure,
cardiac performance, ventricular performance, ventricular failure,
atrial performance, ischemia, myocardial infarction, pulmonary
stenosis, atrial septal defects, etc.
[0066] FIG. 1 illustrates generally an example of a system 100
including an implantable medical device 105, which includes a
respiration sensor 110, a respiration phase detector 115, a heart
sound sensor 120, a heart sound detector 125, and a processor 130.
In other examples, the respiration phase detector 115, the heart
sound detector 125, or the processor 130, can be an implantable
component external to the implantable medical device 105, or can be
an external component. In other examples, some or all of the
functionality of the respiration phase detector 115, or the heart
sound detector 125, can be implemented in the processor 130.
[0067] In this example, the respiration sensor 110 is configured to
sense a respiration signal of a subject. The respiration signal can
include any signal indicative of the respiration of the subject,
such as inspiration, expiration, or any combination, permutation,
or component of the respiration of the subject. The respiration
sensor 110 can be configured to produce a respiration signal, such
as an electrical or optical respiration signal, that includes
information about the respiration of the subject. In certain
examples, the respiration sensor 110 can include an implantable
sensor including at least one of an accelerometer, an impedance
sensor, and a pressure sensor.
[0068] In an example, the respiration sensor 110 can include an
accelerometer configured to sense an acceleration signal indicative
of a cyclical variation indicative of respiration, such as that
disclosed in the commonly assigned Kadhiresan et al. U.S. Pat. No.
5,974,340 entitled "APPARATUS AND METHOD FOR MONITORING REPSIRATORY
FUNCTION IN HEART FAILURE PATIENTS TO DETERMINE EFFICACY OF
THERAPY," (herein "Kadhiresan et al. '340") which is hereby
incorporated by reference in its entirety, including its disclosure
of using an accelerometer to detect respiration. In another
example, the respiration sensor 110 can include a vibration sensor,
such as that disclosed in the commonly assigned Hatlestad et al.
U.S. Pat. No. 6,949,075 entitled "APPARATUS AND METHOD FOR
DETECTING LUNG SOUNDS USING AN IMPLANTED DEVICE," (herein
"Hatlestad et al. '075") which is hereby incorporated by reference
in its entirety, including its disclosure of using a vibration
sensor to detect respiration. In other examples, other
accelerometer configurations can be used to sense the respiration
signal.
[0069] In another example, the respiration sensor 110 can include
an impedance sensor configured to sense an impedance signal
indicative of respiration, such as that disclosed in the commonly
assigned Kadhiresan et al. '340, incorporated by reference in its
entirety. In another example, the respiration sensor 110 can
include a transthoracic impedance sensor, such as that disclosed in
the commonly assigned Hartley et al. U.S. Pat. No. 6,076,015
entitled "RATE ADAPTIVE CARDIAC RHYTHM MANAGEMENT DEVICE USING
TRANSTHROACIC IMPEDANCE," which is hereby incorporated by reference
in its entirety, including its disclosure of using a thoracic
impedance sensor to detect respiration. In other examples, other
impedance sensor configurations can be used to sense the
respiration signal.
[0070] In another example, the respiration sensor 110 can include a
pressure sensor configured to sense a pressure signal indicative of
respiration, such as that disclosed in the commonly assigned
Hatlestad et al. '075, incorporated by reference in its entirety,
including its disclosure of sensing a pressure signal indicative of
respiration. In other examples, other pressure sensor
configurations, such as a pulmonary artery pressure sensor, a
ventricular pressure sensor, a thoracic pressure sensor, etc., can
be used to sense a respiration signal.
[0071] In the example of FIG. 1, the respiration phase detector 115
is coupled to the respiration sensor 110. The respiration phase
detector 115 can be configured to receive the respiration signal
from the respiration sensor 110. Generally, the respiration phase
detector 115 can be configured to detect at least a particular
portion of at least one phase of the respiration signal. In certain
examples, this includes at least portion of at least one of an
inspiration, an expiration, a transition between inspiration and
expiration, and a transition between expiration and
inspiration.
[0072] In this example, the heart sound sensor 120 can be
configured to sense a heart sound signal of a subject. The heart
sound signal can include any signal indicative of at least a
portion of at least one heart sound of the subject. A heart sound
of the subject can include an audible or mechanical noise or
vibration indicative of blood flow through the heart or valve
closures of the heart. A heart sound of the subject can include S1,
S2, S3, S4, or any components thereof, such as A2, P2, etc. The
heart sound sensor 120 can be configured to produce a heart sound
signal, such as an electrical or optical heart sound signal, that
includes information about the heart sound signal of the subject.
The heart sound sensor 120 can include any device configured to
sense the heart sound signal of the subject. In certain examples,
the heart sound sensor 120 can include an implantable sensor
including at least one of an accelerometer, an acoustic sensor, a
microphone, etc.
[0073] In an example, the heart sound sensor 120 can include an
accelerometer configured to sense an acceleration signal indicative
of the heart sound of the subject, such as that disclosed in the
commonly assigned Carlson et al. U.S. Pat. No. 5,792,195 entitled
"ACCELERATION SENSED SAFE UPPER RATE ENVELOPE FOR CALCULATING THE
HEMODYNAMIC UPPER RATE LIMIT FOR A RATE ADAPTIVE CARDIAC RHYTHM
MANAGEMENT DEVICE," which is hereby incorporated by reference in
its entirety including its disclosure of accelerometer detection of
heart sounds, or such as that disclosed in the commonly assigned
Siejko et al. U.S. patent application Ser. No. 10/334,694, entitled
"METHOD AND APPARATUS FOR MONITORING OF DIASTOLIC HEMODYNAMICS,"
filed Dec. 30, 2002 (Attorney Docket No. 279.576US1) (herein
"Siejko et al. '694"), which is hereby incorporated by reference in
its entirety including its disclosure of accelerometer detection of
heart sounds. In other examples, other accelerometer or
acceleration sensor configurations can be used to sense the heart
sound signal.
[0074] In another example, the heart sound sensor 120 can include
an acoustic sensor configured to sense an acoustic energy
indicative of the heart sound of the subject, such as that
disclosed in the commonly assigned Siejko et al. '694, incorporated
by reference in its entirety. In other examples, other acoustic
sensor or microphone configurations can be used to sense the heart
sound signal.
[0075] In the example of FIG. 1, the heart sound detector 125 is
coupled to the heart sound sensor 120. The heart sound detector 125
can be configured to receive the heart sound signal from the heart
sound sensor 120. Generally, the heart sound detector 125 can be
configured to detect at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound. In certain examples, this includes at
least one of an amplitude of a heart sound, a magnitude of a heart
sound, a total energy of a heart sound, an interval between one
heart sound feature and another heart sound feature, at least one
heart sound characteristic normalized by at least one other heart
sound characteristic, etc. (e.g., an amplitude or magnitude of S1,
an amplitude or magnitude of S2, an amplitude or magnitude of S3,
an amplitude or magnitude of S4, the existence of a split-S2, a
split-S2 time interval, a time interval between S1 and S2 ("S1-S2
time interval"), a time interval between S2 and S3 ("S2-S3 time
interval"), a characteristic of S3 normalized by a characteristic
of S1, etc.).
[0076] In the example of FIG. 1, the processor 130 is coupled to
the respiration phase detector 115 and the heart sound detector
125. The processor 130 can be configured to receive the at least a
portion of at least one phase of the respiration signal from the
respiration phase detector 115, and the at least a portion of the
at least one heart sound or component of the heart sound signal
from the heart sound detector 125. Generally, the processor 130 can
be configured to automatically produce at least one heart sound
trend using information from the respiration phase detector 115 and
the heart sound detector 125.
[0077] Generally, a heart sound trend can include an index of
information about at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound. In this example, the heart sound trend
includes an index of information about at least one measurement,
feature, characteristic, computation, or interval of at least a
portion of at least one heart sound arranged, sorted, or otherwise
indexed using the at least a portion of the at least one phase of
the respiration signal. Illustrative examples of heart sound trends
arranged, sorted, or otherwise indexed using the at least a portion
of the at least one phase of the respiration signal include an
index of at least one S1 amplitude during inspiration, an index of
at least one S1 amplitude during expiration, an index of at least
one S2 amplitude during inspiration, an index of the rate of change
of S1 amplitude (".DELTA.S1") during inspiration, an index of at
least one S1-S2 time interval during inspiration, a ratio or a
relative measurement or a comparison between at least one S1
amplitude during inspiration and at least one S1 amplitude during
expiration, etc.
[0078] FIG. 2 illustrates generally an example of portions of a
system 200 including a heart sound detector 125 and a cardiac
sensor 135. In certain examples, the heart sound detector 125, or
the cardiac sensor 135, can be included in the implantable medical
device 105. In other examples, the heart sound detector 125 can be
an implantable component external to the implantable medical device
105, or can be an external component. In an example, some or all of
the functionality of the heart sound detector 125 can be
implemented in the processor 130.
[0079] In this example, the cardiac sensor 135 can be configured to
sense a cardiac signal of a subject. The cardiac signal can include
any signal indicative of the electrical or mechanical cardiac
activity of the heart, e.g., an electrocardiogram ("ECG") signal,
an impedance signal, an acceleration signal, etc. The cardiac
sensor 135 can be configured to produce a cardiac signal, such as
an electrical or optical cardiac signal, that includes information
about the cardiac signal of the subject. The cardiac sensor 135 can
include any device configured to sense the cardiac activity of the
subject. In certain examples, the cardiac sensor 135 can include an
intrinsic cardiac signal sensor, such as one or more than one
electrode or lead to sense one or more than one depolarization, or
a mechanical sensor, such as an impedance sensor or an
accelerometer to sense one or more than one contraction.
[0080] In the example of FIG. 2, the heart sound detector 125 is
coupled to the cardiac sensor 135. The heart sound detector 125 can
be configured to receive the cardiac signal from the cardiac sensor
135 or a heart sound signal from the heart sound sensor 120. In
this example, the heart sound detector 125 can be configured to
detect at least one measurement, feature, characteristic,
computation, or interval of at least a portion of at least one
heart sound using the heart sound sensor 120 and the cardiac sensor
135.
[0081] Generally, the at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound includes at least one measurement,
feature, characteristic, computation, or interval between at least
one cardiac signal feature and at least one heart sound signal
feature. Typically, the at least one cardiac signal feature can
include at least one feature or component of an ECG signal, e.g.,
at least one component of a P-wave, at least one component of a
Q-wave, at least one component of a R-wave, at least one component
of a S-wave, at least one component of a T-wave, or any combination
or permutation of features or components of the ECG signal, or any
mechanical cardiac features of a pressure signal or acceleration
signal indicative of the cardiac activity of a subject. In certain
examples, the at least one measurement, feature, characteristic,
computation, or interval between at least one cardiac signal
feature and at least one heart sound signal feature includes a
systolic time interval ("STI") (e.g., a total electromechanical
systole ("Q-S2"), a pre-ejection phase ("PEP"), a left-ventricular
ejection time ("LVET"), an isovolumetric contraction time ("ICT"),
a S1-S2 time interval, etc.), a long Q-S1 time interval, a R-S1
time interval, R-S2 interval, etc.
[0082] FIG. 3 illustrates generally an example of portions of a
system 300 including a heart sound detector 125, a gating circuit
126, and a cardiac sensor 135. In certain examples, the heart sound
detector 125, the gating circuit 126, or the cardiac sensor 135,
can be included in the implantable medical device 105. In other
examples, the heart sound detector 125, or the gating circuit 126,
can be an implantable component external to the implantable medical
device 105, or can be an external component. In other examples,
some or all of the functionality of the heart sound detector 125,
or the gating circuit 126, can be implemented in the processor
130.
[0083] Generally, the cardiac sensor 135 can be configured to sense
a cardiac signal of a subject. In this example, the gating circuit
126 is coupled to the cardiac sensor 135 and the heart sound
detector 125. The gating circuit 126 can be configured to receive
the cardiac signal from the cardiac sensor 135, or the heart sound
signal from the heart sound sensor 120 or the heart sound detector
125. The gating circuit 126 can be configured to obtain a gated
heart sound signal, such as by gating the heart sound signal using
information from the cardiac signal. Typically, the gating circuit
126 gates the heart sound signal using at least one cardiac signal
feature of the cardiac signal to detect at least a portion of at
least one heart sound. In an example, the gated heart sound signal
can include at least a portion of at least one heart sound, such as
the S1, S2, etc.
[0084] In an example, the gating circuit 126 can be configured to
implement a detection window to detect at least a portion of at
least one heart sound, such as that disclosed in the commonly
assigned Zhu et al. U.S. Pat. No. 6,650,940 entitled
"ACCELEROMETER-BASED HEART SOUND DETECTION FOR AUTOCAPTURE," which
is hereby incorporated by reference in its entirety, including its
disclosure of using a detection window to detect at least one
portion of a heart sound. In other examples, other gating circuit
configurations can be used to detect at least a portion of at least
one heart sound.
[0085] FIG. 4 illustrates generally an example of portions of a
system 400 including a heart sound sensor 120 and a cardiac sensor
135. In certain examples, the heart sound sensor 120, or the
cardiac sensor 135, can be included in the implantable medical
device 105.
[0086] In the example of FIG. 4, the heart sound sensor 120 can be
enabled or disabled using information from the cardiac sensor 135.
In an example, the heart sound sensor 120 can be enabled during at
least a portion of at least one cardiac cycle. The at least a
portion of the at least one cardiac cycle can be detected using
information from the cardiac signal. In another example, the heart
sound sensor 120 can be enabled for a period of time using
information from the cardiac sensor 135, such as being enabled for
at least a portion of at least one cardiac cycle every ten cardiac
cycles, being enabled for at least a portion of at least one
cardiac cycle every one hundred cardiac cycles, etc., or such as
being enabled for at least a portion of at least one cardiac cycle
once or more than once per hour, day, week, etc. In other examples,
the heart sound sensor 120 can be enabled during a cardiac event,
such as an ischemic event, a myocardial infarction event, an
increased or decreased heart rate, etc.
[0087] FIG. 5 illustrates generally an example of portions of a
system 500 including a respiration phase detector 115 and a heart
sound sensor 120. In certain examples, the respiration phase
detector 115, or the heart sound sensor 120, can be included in the
implantable medical device 105. In other examples, the respiration
phase detector 115 can be an implantable component external to the
implantable medical device 105, or can be an external component. In
an example, some or all of the functionality of the respiration
phase detector 115 can be implemented in the processor 130.
[0088] In the example of FIG. 5, the heart sound sensor 120 can be
enabled or disabled using information from the respiration phase
detector 115. In an example, the heart sound sensor 120 can be
enabled during at least a portion of at least one respiration
phase. The at least a portion of the at least one respiration phase
can be detected using information from the respiration sensor. In
another example, the heart sound sensor 120 can be enabled for a
period of time using information from the respiration phase
detector 115, such as being enabled for at least a portion of at
least one respiration phase or cycle every ten respiration phases
or cycles, being enabled for at least a portion of at least one
respiration phase or cycle every one hundred respiration phases or
cycles, etc., or such as being enabled for at least a portion of at
least one respiration phase or cycle once or more than once per
hour, day, week, etc. In other examples, the heart sound sensor 120
can be enabled during a respiration event, such as an apnea event,
an increased or decreased respiratory rate, etc.
[0089] FIG. 6 illustrates generally an example of portions of a
system 600 including a respiration phase detector 115, a gating
circuit 126, and a heart sound detector 125. In certain examples,
the respiration phase detector 115, the gating circuit 126, or the
heart sound detector 125, can be included in the implantable
medical device 105, can be an implantable component external to the
implantable medical device 105, or can be an external component. In
other examples, some or all of the functionality of the respiration
phase detector 115, the gating circuit 126, or the heart sound
detector 125, can be implemented in the processor 130.
[0090] Generally, the respiration phase detector 115 can be
configured to detect at least a portion of at least one phase of a
respiration signal of a subject. In this example, the gating
circuit 126 is coupled to the respiration phase detector 115 and
the heart sound detector 125. The gating circuit 126 can be
configured to receive the at least a portion of at least one phase
of the respiration signal from the respiration phase detector 115,
or the heart sound signal from the heart sound sensor 120 or the
heart sound detector 125. The gating circuit 126 can be configured
to obtain a gated heart sound signal, such as by gating the heart
sound signal using information from the respiration signal.
Typically, the gating circuit 126 gates the heart sound signal
using at least one respiration feature of the respiration signal to
detect at least a portion of at least one heart sound occurring
during at least a portion of at least one phase of the respiration
signal. In an example, the gated heart sound signal can include at
least a portion of at least one heart sound, such as the S1, S2,
etc., occurring during at least a portion of at least one phase of
the respiration signal, such as at least a portion of inspiration,
expiration, or the transition from inspiration to expiration or
expiration to inspiration.
[0091] FIG. 7 illustrates generally an example of portions of a
system 700 including a processor 130 and an external display 140.
In certain examples, the processor 130 can be included in the
implantable medical device 105, can be an implantable component
external to the implantable medical device 105, or can be an
external component.
[0092] Generally, the processor 130 can be configured to
automatically produce at least one heart sound trend using
information from a respiration signal of a subject and a heart
sound signal of the subject. In this example, the external display
140 is coupled to the processor 130. The external display 140 can
be configured to receive information from the processor 130. The
external display 140 can be configured to display information from
the processor 130, such as information about the at least one heart
sound trend. In certain examples, the external display can include
an external programmer, a remote patient monitoring system, a
computing device, such as a personal digital assistant ("PDA"), a
notebook computer, a desktop computer, a cellular phone, or other
computing device, or an external display, such as a liquid crystal
display ("LCD") or other external display. In an example, the
external display 140 can include a memory to store information from
the processor 130. In another example, the external display 140 can
be configured to further process the information received from the
processor 130. The external display 140 can also be configured to
communicate to an external device, such as an external repeater.
The external repeater can be configured to communicate, such as by
an e-mail or other communication, to a user, such as a physician or
other caregiver, or a subject.
[0093] FIG. 8 illustrates generally an example of portions of a
system 800 including a processor 130 and an analysis module 145. In
certain examples, the processor 130, or the analysis module 145,
can be included in the implantable medical device 105, can be an
implantable component external to the implantable medical device
105, or can be an external component. In an example, some or all of
the functionality of the analysis module 145 can be implemented in
the processor 130.
[0094] Generally, the processor 130 can be configured to
automatically produce at least one heart sound trend using
information from a respiration signal and a heart sound signal of a
subject. In this example, the analysis module 145 is coupled to the
processor 130. The analysis module 145 can be configured to receive
information from the processor 130. The analysis module 145 can be
configured to provide information about at least one cardiovascular
status using information from the at least one heart sound
trend.
[0095] FIG. 9 illustrates generally an example of portions of a
system 900 including a processor 130, an analysis module 145, and a
blood volume sensor 150. In certain examples, the processor 130,
the analysis module 145, or the blood volume sensor 150, can be
included in the implantable medical device 105. In other examples,
the processor 130, or the analysis module 145, can be an
implantable component external to the implantable medical device
105, or can be an external component. In an example, some or all of
the functionality of the analysis module 145 can be implemented in
the processor 130.
[0096] In this example, the blood volume sensor 150 is coupled to
the processor 130. Generally, the blood volume sensor 150 can be
configured to sense a blood volume of a subject. In an example, the
blood volume can include a stroke volume, a cardiac output, etc.
Additionally or alternatively, the blood volume of the subject can
be determined, estimated, or correlated using a respiration signal,
such as a minute ventilation ("MV") signal, a tidal volume signal,
or other respiration signal, an impedance signal, such as a
transthoracic impedance signal or other impedance signal, or a
pressure signal, such as a thoracic pressure signal or other
pressure signal. The blood volume sensor 150 can include any sensor
configured to sense the blood volume of the subject.
[0097] In an example, the blood volume sensor 150 can include a MV
sensor configured to sense a ventilation signal indicative of the
blood volume of the subject, such as that disclosed in the commonly
assigned Larsen et al. U.S. Pat. No. 6,868,346 entitled "MINUTE
VENTILATION SENSOR WITH AUTOMATIC HIGH PASS FILTER ADJUSTMENT,"
which is hereby incorporated by reference in its entirety,
including its disclosure of an MV sensor that senses a ventilation
signal. In another example, the blood volume sensor 150 can include
a MV sensor configured to sense a ventilation signal indicative of
the ventilation of the subject, such as that disclosed in the
commonly assigned Yonce U.S. Pat. No. 6,741,886 entitled "ECG
SYSTEM WITH MINUTE VENTILATION DETECTOR," which is hereby
incorporated by reference in its entirety, including its disclosure
of an MV sensor and ventilation sensing.
[0098] In yet another example, the blood volume sensor 150 can
include at least one of a MV sensor configured to sense a
ventilation signal indicative of the blood volume of the subject
and an impedance sensor configured to sense an impedance signal
indicative of the blood volume of a subject, such as that disclosed
in the commonly assigned Hartley et al. U.S. Pat. No. 6,076,015
"RATE ADAPTIVE CARDIAC RHYTHM MANAGEMENT DEVICE USING TRANSTHORACIC
IMPEDANCE," Hartley et al. U.S. Pat. No. 6,161,042 "RATE ADAPTIVE
CARDIAC RHYTHM MANAGEMENT DEVICE USING TRANSTHORACIC IMPEDANCE," or
Hartley et al. U.S. Pat. No. 6,463,326 "RATE ADAPTIVE CARDIAC
RHYTHM MANAGEMENT DEVICE USING TRANSTHORACIC IMPEDANCE," which are
hereby incorporated by reference in their entirety including their
disclosure of using an MV sensor to sense a ventilation signal
indicative of blood volume and an impedance sensor to sense an
impedance signal indicative of blood volume. In other examples,
other MV sensor configurations can be used to sense a blood
volume.
[0099] In another example, the blood volume sensor 150 can include
an impedance sensor configured to sense an impedance signal
indicative of the blood volume of the subject, such as that
disclosed in the commonly assigned Salo et al. U.S. Pat. No.
5,190,035 "BIOMEDICAL METHOD AND APPARATUS FOR CONTROLLING THE
ADMINISTRATION OF THERAPY TO A PATIENT IN RESPONSE TO CHANGES IN
PHYSIOLOGICAL DEMAND," which is hereby incorporated by reference in
its entirety including its disclosure of a blood volume sensor.
[0100] In yet another example, the blood volume sensor 150 can
include an impedance sensor configured to sense an impedance signal
indicative of the blood volume of the subject, such as that
disclosed in the commonly assigned Citak et al. U.S. Pat. No.
4,773,401 "PHYSIOLOGIC CONTROL OF PACEMAKER RATE USING PRE-EJECTION
INTERVAL AS THE CONTROLLING PARAMETER," which is hereby
incorporated by reference in its entirety including its disclosure
of detecting an impedance signal indicative of blood volume. In
other examples, other impedance sensor configurations can be used
to sense a blood volume.
[0101] The blood volume sensor 150, like the heart sound sensor
120, can be gated, such as by using information from the cardiac
sensor 135, the respiration sensor 110, or the respiration phase
detector 115. Further, the blood volume sensor, like the heart
sound sensor 120, can be enabled or disabled, such as by using
information from the cardiac sensor 135, the respiration sensor
110, or the respiration phase detector 115.
[0102] Generally, the processor 130 can be configured to
automatically produce at least one heart sound trend using
information from a respiration signal and a heart sound signal of a
subject. In this example, the processor 130 can be configured to
receive a blood volume signal from the blood volume sensor 150.
[0103] In the example of FIG. 9, the analysis module 145 is coupled
to the processor 130. The analysis module 145 can be configured to
receive information from the processor 130, such as the at least
one heart sound trend and the blood volume signal. The analysis
module 145 can be configured to provide information about at least
one cardiovascular status using information from the at least one
heart sound trend and the blood volume signal.
[0104] FIG. 10 illustrates generally an example 1000 of a
relationship between a respiration signal 1005, including a
inspiratory respiration signal component 1006 and an expiratory
respiration signal component 1007, and a heart sound signal 1010,
including an inspiratory heart sound signal component 1011 and an
expiratory heart sound signal component 1012.
[0105] Typically, the heart sound signal varies with respiration.
In the example of FIG. 10, the heart sound signal 1010 generally
has a larger magnitude during the expiratory respiration signal
component 1007 of the respiration signal 1005, such as at the
expiratory heart sound signal component 1012, than during the
inspiratory respiration signal component 1006 of the respiration
signal 1005, such as at the inspiratory heart sound signal
component 1011.
[0106] FIG. 11 illustrates generally an example 1100 of a
relationship between the amplitude of a first heart sound ("S1
amplitude") 1101 and the rate of pressure change ("dP/dt") 1102,
including a regression line 1105 and a correlation value
("R.sup.2") 1110.
[0107] Regression analysis is generally used to determine the
relationship between two or more measurements. A regression line of
a set of data is typically the line of best fit, or the line that
comes closest to all data points in the set. Correlation is
generally the degree to which the two or more measurements are
similar or related. A higher value of correlation corresponds to a
higher degree of relation. Cleaner and more accurate signals
typically have a higher value of correlation.
[0108] In the example of FIG. 11, S1 amplitude 1101 includes S1
amplitude during inspiration and expiration. In this example, the
regression line 1105 is the line of best fit for the data of S1
amplitude 1101 versus dP/dt 1102. The R.sup.2 1110 for the S1
amplitude 1101 versus dP/dt 1102 is 0.4209.
[0109] FIG. 12 illustrates generally an example 1200 of a
relationship between the amplitude of a first heart sound ("S1
amplitude") 1201 and the rate of pressure change ("dP/dt") 1202,
including an inspiratory first heart sound amplitude ("inspiratory
S1 amplitude") 1205 versus dP/dt 1202, an inspiratory regression
line 1206, an inspiratory correlation value ("inspiratory R.sup.2")
1207, an expiratory first heart sound amplitude ("expiratory S1
amplitude") 1210 versus dP/dt 1202, an expiratory regression line
1211, and an expiratory correlation value ("expiratory R.sup.2")
1212.
[0110] Generally, FIG. 12 illustrates that detecting heart sounds
during the different phases of the respiration signal, such as
inspiration, expiration, etc., has a higher correlation than other
modes of detection, such as that shown in example 1100. In the
example of FIG. 12, inspiratory S1 amplitude 1205 includes S1
amplitude during inspiration. In this example, the inspiratory
regression line 1206 is the line of best fit for the data of
inspiratory S1 amplitude 1205 versus dP/dt 1202. The inspiratory
R.sup.2 1207 for the inspiratory S1 amplitude 1205 versus dP/dt
1202 is 0.5719. The expiratory regression line 1211 is the line of
best fit for the data of expiratory S1 amplitude 1210 versus dP/dt
1202. The expiratory R.sup.2 1212 for the expiratory S1 amplitude
1210 versus dP/dt 1202 is 0.8581.
[0111] FIG. 13 illustrates generally an example 1300 of a
relationship between a first heart sound ("S1") 1301 and a blood
volume 1302, including an increased performance curve 1305, a
normal curve 1310, and a heart failure curve 1315.
[0112] The relationship between S1 1301 and the blood volume 1302
of the example 1300 is sometimes called the Frank-Starling curve.
Generally, the Frank-Starling curve can be used to measure cardiac
performance. The Frank-Starling curve typically demonstrates that
performance of a failing heart can improve with either an increase
in contractility or a decrease in afterload. Normal heart function
is typically associated with adequate tissue perfusion without
pulmonary congestion. Heart failure generally results in a downward
shift of the Frank-Starling curve, and concurrently a decreased
operating slope of the Frank-Starling curve. Typically, this
downward shift or decreased operating slope can result in
hypoperfusion, pulmonary congestion, etc.
[0113] FIG. 14 illustrates generally an example of a method 1400
including sensing a respiration signal, detecting at least one
phase of a respiration signal, sensing a heart sound signal,
detecting at least one heart sound, and automatically producing at
least one heart sound trend.
[0114] At 1405, a respiration signal is sensed. The respiration
signal can include any signal indicative of the respiration of a
subject, such as inspiration, expiration, or any combination,
permutation, or component of the respiration of the subject. In an
example, the respiration signal can be sensed using the respiration
sensor 110.
[0115] At 1410, at least one phase of a respiration signal is
detected. The at least one phase of the respiration signal can be
detected using the respiration signal. In certain examples, the at
least one phase of the respiration signal includes at least a
portion of at least one of an inspiration, an expiration, a
transition between inspiration and expiration, a transition between
expiration and inspiration, etc. In certain examples, an
inspiration, an expiration, the transitions between inspiration and
expiration, etc., can be determined using the respiration signal,
such as by differentiating the respiration signal to attain the
slope of the respiration signal, by detecting peaks and valleys of
the respiration signal, or by using other filtering methods or
signal characteristics. In an example, the at least one phase of
the respiration signal can be detected using the respiration phase
detector 115.
[0116] In an example, the at least one phase of the respiration
signal includes an inspiration of one respiration cycle. A
respiration cycle can include one full inspiration and expiration,
one full expiration and inspiration, or any permutation or
combination of a full inspiration and a full expiration. In other
examples, the at least one phase of the respiration signal includes
an expiration of one respiration cycle, a portion of an inspiration
of one respiration cycle, a portion of an expiration of one
respiration cycle, a portion of an inspiration and an expiration of
one respiration cycle, a portion of an inspiration or an expiration
of more than one respiration cycle, a portion of an inspiration and
an expiration of more than one respiration cycle, etc.
[0117] At 1415, a heart sound signal is sensed. The heart sound
signal can include any signal indicative of at least a portion of
at least one heart sound of the subject. A heart sound of the
subject can include an audible or mechanical noise or vibration
indicative of blood flow through a heart or one or more than one
valve closure of the heart. This noise or vibration can include S1,
S2, S3, S4, or any components thereof, such as A2, P2, etc. In an
example, the heart sound signal can be sensed using the heart sound
sensor 120.
[0118] At 1420, at least one heart sound is detected. The at least
one heart sound can be detected using the heart sound signal.
Generally, the at least one heart sound includes at least one
measurement, feature, characteristic, computation, or interval of
at least a portion of the heart sound signal. In certain examples,
the at least one measurement, feature, characteristic, computation,
or interval of the at least a portion of the heart sound signal
includes at least one of an amplitude of a heart sound, a magnitude
of a heart sound, a total energy of a heart sound, an interval
between one heart sound feature and another heart sound feature, at
least one heart sound characteristic normalized by at least one
other heart sound characteristic, etc. (e.g., an amplitude or
magnitude of S1, an amplitude or magnitude of S2, an amplitude or
magnitude of S3, an amplitude or magnitude of S4, the existence of
a split-S2, a split-S2 time interval, a S1-S2 time interval, a
S2-S3 time interval, a characteristic of S3 normalized by a
characteristic of S1, etc.). In an example, the at least one heart
sound can be detected using the heart sound detector 125.
[0119] At 1425, at least one heart sound trend is automatically
produced. The at least one heart sound trend can be automatically
produced using the at least one phase of the respiration signal,
detected at 1410, and the at least one heart sound, detected at
1420. At 1425, the at least one heart sound trend includes an index
of information about at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound arranged, sorted, or otherwise indexed
using the at least a portion of the at least one phase of the
respiration signal. In an example, the at least one heart sound
trend can be automatically produced using the processor 130.
[0120] FIG. 15 illustrates generally an example of portions of a
method 1500 including sensing a heart sound signal, sensing a
cardiac signal, and detecting at least one heart sound.
[0121] At 1515, a heart sound signal is sensed. The heart sound
signal can include any signal indicative of at least a portion of
at least one heart sound of the subject. In an example, the heart
sound signal can be sensed using the heart sound sensor 120.
[0122] At 1516, a cardiac signal is sensed. The cardiac signal can
include any signal indicative of the electrical or mechanical
cardiac activity of a heart. In an example, the cardiac signal can
be sensed using the cardiac sensor 135.
[0123] At 1520, at least one heart sound is detected. The at least
one heart sound can be detected using the heart sound signal and
the cardiac signal. Generally, the at least one heart sound can
include at least one measurement, feature, characteristic,
computation, or interval between at least one cardiac signal
feature and at least one heart sound signal feature. Typically, the
at least one cardiac signal feature can include at least one
feature or component of an ECG signal, e.g., at least one component
of a P-wave, at least one component of a Q-wave, at least one
component of a R-wave, at least one component of a S-wave, at least
one component of a T-wave, or any combination or permutation of
features or components of the ECG signal, or any mechanical cardiac
features of a pressure signal or acceleration signal indicative of
the cardiac activity of a subject. In certain examples, the at
least one measurement, feature, characteristic, computation, or
interval between at least one cardiac signal feature and at least
one heart sound signal feature includes a STI (e.g., Q-S2, PEP,
LVET, ICT, etc.), a long Q-S1 time interval, a R-S1 time interval,
R-S2 interval, etc. In an example, the at least one heart sound can
be detected using the heart sound sensor 120.
[0124] FIG. 16 illustrates generally an example of portions of
method 1600 including sensing a heart sound signal, sensing a
cardiac signal, and gating the heart sound signal.
[0125] At 1615, a heart sound signal is sensed. The heart sound
signal can include any signal indicative of at least a portion of
at least one heart sound of the subject. In an example, the heart
sound signal can be sensed using the heart sound sensor 120.
[0126] At 1616, a cardiac signal is sensed. The cardiac signal can
include any signal indicative of the electrical or mechanical
cardiac activity of a heart. In an example, the cardiac signal can
be sensed using the cardiac sensor 135.
[0127] At 1635, the heart sound signal is gated. The heart sound
signal can be gated using information from the cardiac signal.
Typically, the heart sound signal can be gated in order to detect
at least a portion of at least one heart sound, such as S1, S2,
etc. In an example, the heart sound signal can be gated using the
gating circuit 126.
[0128] In an example, at 1635, the heart sound signal is gated
using a first feature of the cardiac signal and a second feature of
the cardiac signal. In another example, at 1635, the heart sound
signal is gated using a first feature of the cardiac signal and a
time interval. In an example, the time interval has a duration from
100-300 milliseconds.
[0129] FIG. 17 illustrates generally an example of portions of a
method 1700 including sensing a cardiac signal and enabling or
disabling the heart sound sensor.
[0130] At 1716, a cardiac signal is sensed. The cardiac signal can
include any signal indicative of the electrical or mechanical
cardiac activity of a heart. In an example, the cardiac signal can
be sensed using the cardiac sensor 135.
[0131] At 1740, the heart sound sensor is enabled or disabled.
Generally, enabling or disabling the heart sound sensor can reduce
power consumption. The heart sound sensor can be enabled or
disabled using information from the cardiac signal, such as at
least one specific cardiac feature. In an example, the heart sound
sensor can be enabled or disabled during at least a portion of at
least one cardiac cycle, where the cardiac cycle is determined
using the cardiac signal. In other examples, the heart sound sensor
can be enabled or disabled during at least a portion of at least
one cardiac cycle during at least one specific cardiac cycle or
time period, such as during at least a portion of at least one
cardiac cycle every fifth cardiac cycle, or during at least a
portion of at least one cardiac cycle for ten consecutive cardiac
cycles once per hour, etc. In other examples, the heart sound
sensor can be enabled during specific cardiac events, such as an
ischemic event, a myocardial infarction event, etc., or disabled
during specific cardiac events, such as during normal cardiac
function.
[0132] FIG. 18 illustrates generally an example of portions of a
method 1800 including detecting at least one phase of a respiration
signal and enabling or disabling the heart sound sensor.
[0133] At 1810, at least one phase of a respiration signal is
detected. The at least one phase of the respiration signal can be
detected using the respiration signal. In an example, the at least
one phase of the respiration signal can be detected using the
respiration phase detector 115.
[0134] At 1840, the heart sound sensor is enabled or disabled.
Generally, enabling or disabling the heart sound sensor can reduce
power consumption. The heart sound sensor can be enabled or
disabled using information from the respiration signal. In an
example, the heart sound sensor can be enabled or disabled during
at least a portion of at least one phase of the respiration signal.
In another example, the heart sound sensor can be enabled or
disabled during at least a portion of at least one phase of the
respiration signal during at least one specific respiration cycle
or time period, such as during inspiration every fifth respiration
cycle, or during inspiration for ten consecutive respiration cycles
once per hour, etc. In other examples, the heart sound sensor can
be enabled during specific respiratory events, such as an apnea
event, an increased or decreased respiratory rate, etc., or
disabled during specific respiratory events, such as during normal
respiratory function.
[0135] FIG. 19 illustrates generally an example of portions of a
method 1900 including sensing a heart sound signal, sensing a
respiration signal, and gating the heart sound signal.
[0136] At 1905, a respiration signal is sensed. The respiration
signal can include any signal indicative of the respiration of the
subject, such as inspiration, expiration, or any combination,
permutation, or component of the respiration of the subject. In an
example, the respiration signal can be sensed using the respiration
sensor 110.
[0137] At 1915, a heart sound signal is sensed. The heart sound
signal can include any signal indicative of at least a portion of
at least one heart sound of the subject. In an example, the heart
sound signal can be sensed using the heart sound sensor 120.
[0138] At 1935, the heart sound signal is gated. The heart sound
signal can be gated using information from the respiration signal.
Typically, the heart sound signal can be gated in order to detect
at least a portion of at least one heart sound, such as S1, S2,
etc., during at least a portion of at least one phase of the
respiration signal, such as inspiration, expiration, etc. In an
example, the heart sound signal can be gated using the gating
circuit 126.
[0139] FIG. 20 illustrates generally an example of portions of a
method 2000 including automatically producing at least one heart
sound trend and displaying the at least one heart sound trend.
[0140] At 2025, at least one heart sound trend is automatically
produced. The at least one heart sound trend can be automatically
produced using at least one phase of a respiration signal and at
least one heart sound. The at least one heart sound trend includes
an index of information about at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound arranged, sorted, or otherwise indexed
using at least a portion of at least one phase of the respiration
signal. In an example, the at least one heart sound trend can be
automatically produced using the processor 130.
[0141] At 2045, at least one heart sound trend is displayed. The at
least one heart sound trend can be displayed using an external
display, such as an LCD display or other external display, an
external programmer, a remote patient monitoring system, a
computing device, such as a personal digital assistant ("PDA"), a
notebook computer, a desktop computer, a cellular phone, or other
computing devices. In an example, the at least one heart sound
trend can be displayed using the external display 140.
[0142] FIG. 21 illustrates generally an example of portions of a
method 2100 including automatically producing at least one heart
sound trend and providing information about at least one
cardiovascular status.
[0143] At 2125, at least one heart sound trend is automatically
produced. The at least one heart sound trend can be automatically
produced using at least one phase of a respiration signal and at
least one heart sound. The at least one heart sound trend includes
an index of information about at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound arranged, sorted, or otherwise indexed
using at least a portion of at least one phase of the respiration
signal. In an example, the at least one heart sound trend can be
automatically produced using the processor 130.
[0144] At 2150, information about at least one cardiovascular
status is provided. The information about the at least one
cardiovascular status can be provided using information from the at
least one heart sound trend. The information about at least one
cardiovascular status can include information about heart failure,
cardiac performance, ventricular performance, ventricular failure,
atrial performance, ischemia, myocardial infarction, pulmonary
stenosis, atrial septal defects, etc. In an example, the
information about at least one cardiovascular status is provided
using an analysis module 145.
[0145] Generally, S2 can include two components, A2 and P2. In an
example, A2 and P2 timing and location are generally modulated by
respiration. Typically, the aortic valve and pulmonic valve remain
open longer during inspiration. Generally, a split-S2 includes the
separate and distinct A2 and P2 components of S2. In certain
examples, the at least one heart sound trend includes a split-S2
index during inspiration, a split-S2 index during expiration, the
rate of change of a split-S2 interval during inspiration, the
existence of a split-S2 during inspiration, etc.
[0146] Generally, during inspiration, negative intrathoracic
pressure can cause increased blood return into the right side of
the heart. The increased blood volume in the right ventricle can
cause the pulmonic valve to stay open longer during ventricular
systole. This typically can cause an increased delay in the P2
component of S2. Similarly, during expiration, the positive
intrathoracic pressure can cause decreased blood return to the
right side of the heart. The reduced volume in the right ventricle
can allow the pulmonic valve to close earlier at the end of
ventricular systole, typically causing P2 to occur earlier and
closer in time to the A2 component of S2. The split-S2 sound can be
heard generally in younger subjects and during inspiration. During
expiration, the interval between the A2 and P2 components can
shorten and the sounds can merge.
[0147] Typically, the A2 and P2 components of the split-S2 are
wider and vary less with respiration during ventricular failure,
atrial septal defects, pulmonary stenosis, etc., than during normal
cardiac function. Thus, at 2150, the information about at least one
cardiovascular status can include information about split-S2
variation during at least one phase of the respiration signal, such
as inspiration or expiration.
[0148] In another example, the information about at least one
cardiovascular status can include information about the difference
between at least two heart sound trends, such as S1 amplitude
during inspiration and S1 amplitude during expiration, or any other
heart sound trend occurring during at least a first and a second at
least a portion of at least one phase of the respiration
signal.
[0149] FIG. 22 illustrates generally an example of portions of a
method 2200 including automatically producing at least one heart
sound trend, detecting information about a blood volume, and
providing information about at least one cardiovascular status.
[0150] At 2225, at least one heart sound trend is automatically
produced. The at least one heart sound trend can be automatically
produced using at least one phase of a respiration signal and at
least one heart sound. The at least one heart sound trend includes
an index of information about at least one measurement, feature,
characteristic, computation, or interval of at least a portion of
at least one heart sound arranged, sorted, or otherwise indexed
using at least a portion of at least one phase of the respiration
signal. In an example, the at least one heart sound trend can be
automatically produced using the processor 130.
[0151] At 2249, information about a blood volume is detected. The
blood volume can include a stroke volume, cardiac output, etc.
Typically, information about a blood volume can be determined,
estimated, correlated, or otherwise detected using a respiration
signal, such as a MV signal, a tidal volume signal, or other
respiration signal, an impedance signal, such as a transthoracic
impedance signal or other impedance signal, a pressure signal, such
as a thoracic pressure signal or other pressure signal, a flow
meter, etc. In an example, the information about a blood volume can
be detected using the blood volume sensor 150.
[0152] At 2250, information about at least one cardiovascular
status is provided. The information about the at least one
cardiovascular status can be provided using information from the at
least one heart sound trend and information about the blood volume.
The information about at least one cardiovascular status can
include information about heart failure, cardiac performance,
ventricular performance, ventricular failure, atrial performance,
ischemia, myocardial infarction, pulmonary stenosis, atrial septal
defects, hypoperfusion, pulmonary congestion, etc. In an example,
the information about at least one cardiovascular status is
provided using an analysis module 145.
[0153] In an example, diagnostic information about ventricular
performance can be determined by tracking heart sounds during
different respiratory phases, such as inspiration or expiration.
Generally, S1 provides information about the force of contraction
of the heart. Further, blood volume is generally indicative of the
preload of the heart, and typically varies with respiration.
Therefore, using S1 and blood volume, the force of the contraction
of the heart can be measured during different preloads. This
measurement can provide valuable information about a cardiovascular
status, such as ventricular performance.
[0154] In an example, the relationship between S1 (or any other
measurement, feature, characteristic, computation, or interval of
at least a portion of at least one heart sound signal or cardiac
signal) and blood volume can be illustrated using a Frank-Starling
curve. Generally, the Frank-Starling curve can be used to measure
cardiac performance. The Frank-Starling curve typically
demonstrates that performance of a failing heart can improve with
either an increase in contractility or a decrease in afterload. An
example of the Frank-Starling curve is shown in FIG. 13.
[0155] In an example, the operating slope of the Frank-Starling
curve can be measured as the rate of change of at least one
measurement, feature, characteristic, computation, or interval of
at least a portion of at least one heart sound over the rate of
change of blood volume 1302 (".DELTA.V"). In an example, the
operating slope of the Frank-Starling curve can be measured as the
.DELTA.S1 over .DELTA.V.
[0156] In another example, the operating slope of the
Frank-Starling curve can be measured as the rate of change of at
least one measurement, feature, characteristic, computation, or
interval of at least a portion of at least one heart sound
occurring during at least a portion of at least one phase of a
respiration signal over .DELTA.V, such as S1 during inspiration
over .DELTA.V, S1 during expiration over .DELTA.V, etc. Generally,
trending S1, or any other heart sound or heart sound timing,
separately during inspiration, expiration, or any other at least
one phase or portion of at least one phase of the respiration
signal can be used with .DELTA.V to measure the slope of the
Frank-Starling curve. Thus, at 2250, the information about at least
one cardiovascular status can include information about the slope
of the Frank-Starling curve during inspiration and expiration,
inspiration, expiration, or at least a portion of at least one
phase of the respiration signal.
[0157] In another example, at 2250, the information about at least
one cardiovascular status can include information about one or more
than one slope of the Frank-Starling curve during at least a
portion of at least one phase of the respiration signal, or a
comparison between at least a first slope of the Frank-Starling
curve during a first phase of the respiration signal and a second
slope of the Frank-Starling curve during a second phase of the
respiration signal.
[0158] In certain examples, some or all of the functionality of one
or more than one component, such as the respiration phase detector
115, the heart sound detector 125, the gating circuit 126, or the
analysis module 145, can be included in the implantable or external
processor 130.
[0159] In the examples of FIG. 1-22, various examples, including
sensing a respiration signal, detecting at least one phase of a
respiration signal, sensing a heart sound signal, detecting at
least one heart sound signal, automatically producing at least one
heart sound trend, sensing a cardiac signal, gating the heart sound
signal, enabling or disabling the heart sound sensor, displaying
the at least one heart sound trend, providing information about at
least one cardiovascular status, or detecting information about a
blood volume, are disclosed. It is to be understood that these
examples are not exclusive, and can be implemented either alone or
in combination, or in various permutations or combinations.
[0160] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. Many other embodiments will be
apparent to those of skill in the art upon reviewing the above
description. The scope of the invention should, therefore, be
determined with reference to the appended claims, along with the
full scope of equivalents to which such claims are entitled. In the
appended claims, the terms "including" and "in which" are used as
the plain-English equivalents of the respective terms "comprising"
and "wherein." Also, in the following claims, the terms "including"
and "comprising" are open-ended, that is, a system, device,
article, or process that includes elements in addition to those
listed after such a term in a claim are still deemed to fall within
the scope of that claim. Moreover, in the following claims, the
terms "first," "second," and "third," etc. are used merely as
labels, and are not intended to impose numerical requirements on
their objects.
[0161] The Abstract is provided to comply with 37 C.F.R. .sctn.
1.72(b), which requires that it allow the reader to quickly
ascertain the nature of the technical disclosure. It is submitted
with the understanding that it will not be used to interpret or
limit the scope or meaning of the claims. Also, in the above
Detailed Description, various features may be grouped together to
streamline the disclosure. This should not be interpreted as
intending that an unclaimed disclosed feature is essential to any
claim. Rather, inventive subject matter may lie in less than all
features of a particular disclosed embodiment. Thus, the following
claims are hereby incorporated into the Detailed Description, with
each claim standing on its own as a separate embodiment.
* * * * *