U.S. patent application number 13/984070 was filed with the patent office on 2014-05-29 for system for providing an electrical activity map using optical shape sensing.
This patent application is currently assigned to KONINKLIJKE PHILIPS N.V.. The applicant listed for this patent is Dick Dijkkamp, Gerardus Henricus Maria Liempde, Niels Nijhof, Sander Slegt, Hendrikus Bernardus Van Den Brink. Invention is credited to Dick Dijkkamp, Gerardus Henricus Maria Liempde, Niels Nijhof, Sander Slegt, Hendrikus Bernardus Van Den Brink.
Application Number | 20140148677 13/984070 |
Document ID | / |
Family ID | 45774282 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140148677 |
Kind Code |
A1 |
Liempde; Gerardus Henricus Maria ;
et al. |
May 29, 2014 |
SYSTEM FOR PROVIDING AN ELECTRICAL ACTIVITY MAP USING OPTICAL SHAPE
SENSING
Abstract
The invention relates to a system (1) for providing an
electrical activity map of the heart by means of electrical signals
acquired by a plurality of surface electrodes (9). A surface
electrodes positions determination unit (4, 6, 13) determines
positions of the plurality of surface electrodes by means of
optical shape sensing localization. The optical shape sensing
element may comprise a wand (4), or alternatively an optical shape
sensing fiber embedded in the vest comprising the surface
electrodes. The position of a cardiac structure may be determined
using ultrasound. An electrical activity map determination unit
(16) determines the electrical activity map at the cardiac
structure based on the measured electrical signals, the determined
positions of the plurality of electrodes and the position of the
cardiac structure, in particular, of the epicardial surface. Since
optical shape sensing is used for determining the positions of the
plurality of surface electrodes and not, for instance, x-rays, the
electrical activity map can be determined, without necessarily
applying an x-ray radiation dose.
Inventors: |
Liempde; Gerardus Henricus
Maria; (Liempde, NL) ; Van Den Brink; Hendrikus
Bernardus; (Eindhoven, NL) ; Slegt; Sander;
(Best, NL) ; Nijhof; Niels; (Utrecht, NL) ;
Dijkkamp; Dick; (Waalre, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liempde; Gerardus Henricus Maria
Van Den Brink; Hendrikus Bernardus
Slegt; Sander
Nijhof; Niels
Dijkkamp; Dick |
Liempde
Eindhoven
Best
Utrecht
Waalre |
|
NL
NL
NL
NL
NL |
|
|
Assignee: |
KONINKLIJKE PHILIPS N.V.
EINDHOVEN
NL
|
Family ID: |
45774282 |
Appl. No.: |
13/984070 |
Filed: |
February 14, 2012 |
PCT Filed: |
February 14, 2012 |
PCT NO: |
PCT/IB12/50653 |
371 Date: |
February 4, 2014 |
Current U.S.
Class: |
600/389 |
Current CPC
Class: |
A61B 8/12 20130101; A61B
2576/023 20130101; A61B 5/065 20130101; A61B 6/02 20130101; A61B
5/6805 20130101; A61B 6/00 20130101; A61B 6/503 20130101; A61B
6/4441 20130101; A61B 5/0402 20130101; A61B 8/0883 20130101; A61B
8/4254 20130101; A61B 5/0408 20130101; A61B 5/684 20130101; A61B
5/04085 20130101 |
Class at
Publication: |
600/389 |
International
Class: |
A61B 5/00 20060101
A61B005/00; A61B 8/08 20060101 A61B008/08; A61B 8/12 20060101
A61B008/12; A61B 5/0408 20060101 A61B005/0408 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2011 |
EP |
11154871.5 |
Claims
1-13. (canceled)
14. A vest for being worn by a living being, the vest being adapted
to be used for providing an electrical activity map, the vest
comprising: a plurality of surface electrodes for being arranged on
an outer surface of the living being, when the vest is worn by the
living being, and for acquiring electrical signals from the heart
of the living being, an optical shape sensing fiber for generating
an optical shape sensing signal being indicative of the
three-dimensional shape of the optical shape sensing fiber and for
providing the optical shape sensing signal to a surface electrodes
positions calculation unit.
15. A system for providing an electrical activity map of the heart
of a living being by means of electrical signals from the heart
acquired by a plurality of surface electrodes being arranged on an
outer surface of the living being, wherein a vest as defined in
claim 14 is worn by the living being and comprises the plurality of
surface electrodes, the system comprising: a spatial relation
providing unit for providing spatial relations between an optical
shape sensing fiber of the vest and the surface electrodes, a
surface electrodes positions calculation unit for calculating the
positions of the surface electrodes depending on the
three-dimensional shape of the optical shape sensing fiber as
indicated by an optical shape sensing signal provided by the
optical shape sensing fiber and the provided spatial relation, a
cardiac structure position determination unit for determining a
position of a cardiac structure of the living being, wherein the
cardiac structure position determination unit comprises a cardiac
structure position calculation unit for calculating the position of
the cardiac structure based on a) an ultrasound signal received
from an ultrasound unit equipped with an optical shape sensing
sensor, wherein the ultrasound signal is indicative of the position
of the cardiac structure, and b) an optical shape sensing signal
received from the optical shape sensing sensor of the ultrasound
unit, wherein the optical shape sensing signal is indicative of the
position of the ultrasound unit, an electrical activity map
determination unit for determining the electrical activity map at
the cardiac structure based on the electrical signals measured on
the outer surface of the living being, the determined positions of
the plurality of electrodes and the determined position of the
cardiac structure.
16. The system as defined in claim 14, wherein the cardiac
structure position determination unit comprises the ultrasound unit
for generating the ultrasound signal being indicative of the
position of the cardiac structure, wherein the ultrasound unit is
equipped with the optical shape sensing sensor for generating the
optical shape sensing signal being indicative of the position of
the ultrasound unit.
17. The system as defined in claim 14, wherein the ultrasound unit
is a transthoracic echo probe or a transesophageal echo probe.
18. The system as defined in claim 14, wherein the ultrasound
signal represents an ultrasound image and wherein the cardiac
structure calculation unit is adapted to detect the cardiac
structure in the ultrasound image and to calculate the position of
the cardiac structure based on the cardiac structure detected in
the ultrasound image.
19. A method for providing an electrical activity map of the heart
of a living being by means of electrical signals from the heart
acquired by a plurality of surface electrodes being arranged on an
outer surface of the living being, the method comprising:
determining positions of the plurality of surface electrodes,
wherein a vest as defined in claim 14 is worn by the living being
and comprises the plurality of surface electrodes, wherein spatial
relations between an optical shape sensing fiber of the vest and
the surface electrodes are provided by a spatial relation providing
unit, and wherein the positions of the surface electrodes are
calculated depending on a three-dimensional shape of the optical
shape sensing fiber as indicated by an optical shape sensing signal
provided by the optical shape sensing fiber and the provided
spatial relation by a surface electrodes positions calculation
unit, determining a position of a cardiac structure of the living
being, wherein the position of the cardiac structure is determined
based on a) an ultrasound signal received from an ultrasound unit
equipped with an optical shape sensing sensor, wherein the
ultrasound signal is indicative of the position of the cardiac
structure, and b) an optical shape sensing signal received from the
optical shape sensing sensor of the ultrasound unit, wherein the
optical shape sensing signal is indicative of the position of the
ultrasound unit, by an cardiac structure position calculation unit,
determining the electrical activity map at the cardiac structure
based on the electrical signals measured on the outer surface of
the living being, the determined positions of the plurality of
electrodes and the determined position of the cardiac structure by
an electrical activity map determination unit.
20. A computer program for providing an electrical activity map of
the heart of a living being by means of electrical signals from the
heart acquired by a plurality of surface electrodes being arranged
on an outer surface of the living being, the computer program
comprising program code means for causing a system as defined in
claim 14.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a system, a method and a computer
program for providing an electrical activity map of the heart of a
living being by means of electrical signals from the heart acquired
by a plurality of surface electrodes being arranged on an outer
surface of the living being. The invention relates further to a
vest comprising the plurality of surface electrodes.
BACKGROUND OF THE INVENTION
[0002] The article "Noninvasive Characterization of Epicardial
Activation in Humans With Diverse Atrial Fibrillation Patterns" by
P. S. Cuculich et al., Circulation, Journal of the American Heart
Association, 122, pages 1364 to 1372 (2010) discloses a system
comprising an electrode vest with surface electrodes for measuring
electrical potentials on an outer surface of a person. The system
further comprises a reconstruction unit for reconstructing
epicardial electrical potentials based on i) a spatial relation
between the heart surface and the surface electrodes on the outer
surface of the person and ii) the measured electrical potentials.
The spatial relation between the heart surface and the surface
electrodes on the outer surface of the person are obtained by
acquiring an x-ray computed tomography image showing both, the
heart surface and the surface electrodes on the outer surface of
the person. By acquiring the x-ray computed tomography image a
relatively high radiation dose is applied to the person.
SUMMARY OF THE INVENTION
[0003] It is an object of the present invention to provide a
system, a method and a computer program for providing an electrical
activity map of the heart of a living being by means of electrical
signals from the heart acquired by a plurality of surface
electrodes being arranged on an outer surface of the living being,
wherein the radiation dose applied to the person can be reduced, in
particular, can be eliminated. It is a further object of the
present invention to provide a vest for being worn by a living
being and for being used for providing the electrical activity
map.
[0004] In a first aspect of the present invention a system for
providing an electrical activity map of the heart of a living being
by means of electrical signals from the heart acquired by a
plurality of surface electrodes being arranged on an outer surface
of the living being is presented, the system comprising:
[0005] a surface electrodes positions determination unit for
determining positions of the plurality of surface electrodes by
means of optical shape sensing localization,
[0006] a cardiac structure position determination unit for
determining a position of a cardiac structure of the living
being,
[0007] an electrical activity map determination unit for
determining the electrical activity map at the cardiac structure
based on the electrical signals measured on the outer surface of
the living being, the determined positions of the plurality of
electrodes and the determined position of the cardiac
structure.
[0008] Since the positions of the plurality of surface electrodes
are determined by means of optical shape sensing localization,
these positions can be determined without necessarily acquiring a
computed tomography image showing the plurality of surface
electrodes. This allows reducing, in particular, eliminating, the
x-ray radiation dose applied to the living being for generating an
electrical activity map of the heart.
[0009] The cardiac structure is preferentially the epicardial
surface of the heart.
[0010] If the cardiac structure is three-dimensional, in
particular, if the cardiac structure is the three-dimensional
epicardial surface, the position of the cardiac structure
preferentially defines the position of each point of the cardiac
structure at which the electrical activity map should be
determined. Thus, for instance, if the cardiac structure position
determination unit determines the position of the epicardial
surface, it determines at least the positions of the points on the
epicardial surface for which an electrical potential should be
determined for generating the electrical activity map.
[0011] The plurality of surface electrodes can be regarded as being
an element of the system or it can be regarded as being a separate
element, wherein the system is adapted to use the electrical
signals of the surface electrodes for providing the electrical
activity map.
[0012] The plurality of surface electrodes can be incorporated in a
vest that can be worn by the living being. The living being is
preferentially a person, but the living being can also be an
animal.
[0013] The cardiac structure position determination unit comprises
preferentially an ultrasound unit for generating an ultrasound
signal being indicative of the position of the cardiac structure
and a cardiac structure position calculation unit for calculating
the position of the cardiac structure based on the ultrasound
signal. The ultrasound unit is preferentially a transthoracic echo
probe or a transesophageal echo probe. If the ultrasound unit is a
transthoracic echo probe or a transesophageal echo probe, an
ultrasound image of the heart showing the epicardial surface can be
acquired with high quality, thereby allowing the cardiac structure
position calculation unit to determine the position of the
epicardial surface being the preferred cardiac structure with high
accuracy.
[0014] In an embodiment the cardiac structure position calculation
unit is adapted to perform a segmentation procedure for segmenting
the cardiac structure in the ultrasound image for detecting the
cardiac structure. In another embodiment the cardiac structure
position calculation unit is adapted to provide an anatomical
cardiac model being an anatomical model of a heart including the
cardiac structure and to adjust the cardiac model to the ultrasound
image of the heart for detecting the cardiac structure. The
adjustment can just be a rotation and/or translation and optionally
a scaling of the cardiac model, or it can also include a
deformation of the cardiac model. The cardiac model is
preferentially a generalized cardiac model, i.e. a cardiac model
which is, before being adjusted, not specific for a certain person
or animal. It can be determined by, for instance, averaging
segmented hearts of a group of living beings, which may be
segmented in medical images.
[0015] It is further preferred that the ultrasound unit is equipped
with an optical shape sensing sensor for generating an optical
shape sensing signal being indicative of the position of the
ultrasound unit, wherein the cardiac structure position calculation
unit is adapted to determine the position of the cardiac structure
based on the optical shape sensing signal and the ultrasound
signal. The optical shape sensing sensor is preferentially an
optical shape sensing fiber, which may be partly arranged within
the ultrasound unit. This allows determining the position of the
ultrasound unit by optical shape sensing, without applying, for
instance, x-rays to the person. In particular, if the ultrasound
signal represents an ultrasound image of the heart, the epicardial
surface in the ultrasound image can be segmented for determining
the position of the epicardial surface within the ultrasound image
and this determined position of the epicardial surface can be
related to a reference position, i.e. it can be determined within a
reference coordinate system, based on the position of the
ultrasound unit known from the optical shape sensing signal.
[0016] In an embodiment the surface electrodes positions
determination unit comprises a spatial relation providing unit for
providing spatial relations between the positions of the plurality
of surface electrodes and positions of reference marks, wherein the
ultrasound unit is adapted to be brought into contact with the
reference marks, wherein the optical shape sensing sensor is
adapted to generate a respective optical shape sensing signal while
being in contact with a respective reference mark for generating an
optical shape sensing signal being indicative of the position of
the respective reference mark, and wherein the surface electrodes
positions determination unit comprises a surface electrodes
positions calculation unit for calculating the positions of the
surface electrodes depending on the optical shape sensing signals
and the spatial relations. Thus, the ultrasound unit can be used
for two purposes, determining the position of the cardiac structure
and determining the positions of the plurality of surface
electrodes. This reduces the number of elements needed for
determining the electrical activity map of the heart.
[0017] In an embodiment the surface electrodes positions
determination unit comprises a) a spatial relations providing unit
for providing spatial relations between the positions of the
plurality of surface electrodes and positions of reference marks,
b) an optical shape sensing element for generating an optical shape
sensing signal being indicative of the position of the tip of the
optical shape sensing element while being in contact with a
respective reference mark, in order to generate an optical shape
sensing signal being indicative of the position of the respective
reference mark, and c) a surface electrodes positions calculation
unit for calculating the positions of the surface electrodes
depending on the optical shape sensing signal and the spatial
relations. The optical shape sensing element can comprise a wand
and an optical shape sensing fiber connected to the wand, wherein
the tip of the optical shape sensing element is the tip of the
wand. Thus, a user can touch the reference marks with the wand and
determine the positions of the reference marks by determining the
positions of the tip of the wand, while the tip is brought into
contact with the different reference marks. The optical shape
sensing element can be adapted to, for example, continuously
generate an optical shape sensing signal, or to generate an optical
shape sensing signal only after a user has requested an optical
shape sensing signal via an input unit like a button to be pressed.
The tip can also be provided with a pressure sensitive sensor for
detecting whether the tip is in contact with an element or not,
wherein the optical shape sensing element can be adapted to
generate an optical shape sensing signal, when the pressure
sensitive sensor detects that the tip is in contact with a
reference mark.
[0018] The system can further comprise a movement determination
unit for determining a movement of the living being, wherein the
surface electrodes positions determination unit can be adapted to
determine the positions of the plurality of surface electrodes
depending on the determined movement. The movement determination
unit can comprise an optical shape sensing sensor for being
attached to the living being at an attachment location and for
generating an optical shape sensing signal being indicative of an
actual position of the optical shape sensing sensor and a movement
calculation unit for calculating a movement of the living being
depending on the generated optical shape sensing signal. One or
several optical shape sensing sensors can be used for determining
the movement of the living being. The optical shape sensing sensors
can be adapted to be directly attached to the living being or to be
attached to another means being attached to the living being. The
other means can be, for instance, a vest comprising the plurality
of the surface electrodes or patches that can be put on, for
example, a person's thorax. Considering a possible movement of the
person while determining the electrical activity map of the heart
can reduce corresponding possible inaccuracies in the electrical
activity map.
[0019] In an embodiment the surface electrodes positions
determination unit comprises a) an optical shape sensing sensor for
generating optical shape sensing signals being indicative of the
position of the optical shape sensing sensor, b) a spatial relation
providing unit for providing spatial relations between the
positions of the optical shape sensing sensor and the positions of
the surface electrodes, and c) a surface electrodes positions
calculation unit for calculating the positions of the surface
electrodes depending on the generated optical shape sensing signals
and the spatial relations. In this embodiment the optical shape
sensing sensor can be incorporated into a vest which also comprises
the plurality of surface electrodes, wherein the spatial relations
between the optical shape sensing sensor and the plurality of
surface electrodes are known and stored in the spatial relation
providing unit. This allows determining the positions of the
surface electrodes without using, for instance, an optical shape
sensing wand touching the different surface electrodes. For
instance, an electrical activity map can be generated just by using
the vest with the one or several optical shape sensing sensors and
an ultrasound unit also being equipped with an optical shape
sensing sensor such that the position of the ultrasound unit
relative to the surface electrodes can be determined by optical
shape sensing, preferentially without requiring further means for
determining the positions of the surface electrodes and the cardiac
structure. Since less elements are needed for generating the
electrical activity map, the process for determining the electrical
activity map to be performed by, for instance, a physician can be
simplified.
[0020] In a further aspect of the present invention a vest for
being worn by a living being is presented, the vest being adapted
to be used for providing an electrical activity map, the vest
comprising:
[0021] a plurality of surface electrodes for being arranged on an
outer surface of the living being, when the vest is worn by the
living being, and for acquiring electrical signals from the heart
of the living being,
[0022] an optical shape sensing sensor for generating an optical
shape sensing signal being indicative of the position of the
optical shape sensing sensor and for providing the optical shape
sensing signal to a surface electrodes positions determination
unit.
[0023] In a further aspect of the present invention a method for
providing an electrical activity map of the heart of a living being
by means of electrical signals from the heart acquired by a
plurality of surface electrodes being arranged on an outer surface
of the living being is presented, the method comprising:
[0024] determining positions of the plurality of surface electrodes
by means of optical shape sensing localization by a surface
electrodes positions determination unit,
[0025] determining a position of a cardiac structure of the living
being by a cardiac structure position determination unit,
[0026] determining the electrical activity map at the cardiac
structure based on the electrical signals measured on the outer
surface of the living being, the determined positions of the
plurality of electrodes and the determined position of the cardiac
structure by an electrical activity map determination unit.
[0027] In a further aspect of the present invention a computer
program for providing an electrical activity map of the heart of a
living being by means of electrical signals from the heart acquired
by a plurality of surface electrodes being arranged on an outer
surface of the living being is presented, the computer program
comprising program code means for causing a system as defined in
claim 1 to carry out the steps of the method as defined in claim
12, when the computer program is run on a computer controlling the
system.
[0028] It shall be understood that the system of claim 1, the
method of claim 12 and the computer program claim 13 have similar
and/or identical preferred embodiments, in particular, as defined
in the dependent claims.
[0029] It shall be understood that a preferred embodiment of the
invention can also be any combination of the dependent claims with
the respective independent claim.
[0030] These and other aspects of the invention will be apparent
from and elucidated with reference to the embodiments described
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In the following drawings:
[0032] FIG. 1 shows schematically and exemplarily an embodiment of
a system for providing an electrical activity map of the heart of a
living being,
[0033] FIG. 2 shows schematically and exemplarily a further
embodiment of a system for providing an electrical activity map of
the heart of the living being, and
[0034] FIG. 3 shows a flowchart exemplarily illustrating an
embodiment of a method for providing an electrical activity map of
the heart of a living being.
DETAILED DESCRIPTION OF EMBODIMENTS
[0035] FIG. 1 shows schematically and exemplarily an embodiment of
a system for providing an electrical activity map of the heart of a
living being by means of electrical signals from the heart acquired
by a plurality of surface electrodes being arranged on an outer
surface of the living being. The system 1 comprises an optical
shape sensing element 4, 6 for generating an optical shape sensing
signal being indicative of the position of the tip 17 of the
optical shape sensing element 4, 6 while being in contact with a
respective reference mark 2, in order to generate an optical shape
sensing signal being indicative of the position of the respective
reference mark 2. In particular, the living being 30 being, in this
embodiment, a person wears a vest 8 with surface electrodes 9 and
reference marks 2. A user like a physician can use the optical
shape sensing element 4, 6 such that the tip of the optical shape
sensing element 4, 6 consecutively touches the different reference
marks 2 of the vest 8, in order to determine the positions of the
reference marks 2. The vest 8 is electrically connected with a
determination system 11 via an electrical connection 25, in order
to transmit the electrical signals acquired by the surface
electrodes 9 to the electrical activity map determination unit
16.
[0036] The optical shape sensing element 4, 6 comprises a wand 4,
which can be held by a hand 5 of a user, with the tip 17 for being
brought in contact with different reference marks 2 and an optical
shape sensing fiber 6 being connected to the wand 4. The optical
shape sensing element 4, 6 can be adapted to, for example,
continuously generate an optical shape sensing signal or to
generate an optical shape sensing signal only after a user has
requested an optical shape sensing signal via an input unit like a
button to be pressed. The tip can also be provided with a pressure
sensitive sensor for detecting whether the tip is in contact with
an element or not, wherein the optical shape sensing element can be
adapted to generate an optical shape sensing signal, when the
pressure sensitive sensor detects that the tip is in contact with a
reference mark.
[0037] The system 1 comprises a further optical shape sensing
element, i.e. an optical shape sensing sensor 7, 26 for being
attached to the person 30 at an attachment location and for
generating an optical shape sensing signal being indicative of the
actual position of the optical shape sensing sensor 7, 26. In this
embodiment this optical shape sensing sensor comprises a reference
patch 7 connected to an optical shape sensing fiber 26, wherein the
generated optical shape sensing signal is indicative of the
position of the reference patch 7.
[0038] The optical shape sensing signal from the optical shape
sensing sensor 7, 26, which is indicative of the position of the
reference patch 7, and the optical shape sensing signal from the
optical shape sensing element 4, 6, which is indicative of the
position of the tip 17 of the optical shape sensing element 4, 6,
are provided to a surface electrodes positions calculation unit 13
of the determination system 11. The surface electrodes positions
calculation unit 13 is adapted to determine the three-dimensional
positions of the reference marks 2 with respect to the reference
patch 7 based on the provided optical shape sensing signals. For
determining the positions of the reference marks 2 known optical
shape sensing localization method can be used like the optical
shape sensing methods disclosed in WO 2011/141830 A1, which is
herewith incorporated by reference.
[0039] After the positions of the reference markers 2 have been
determined, the surface electrodes positions calculation unit 13
determines the positions of the surface electrodes 9 depending on
the determined positions of the reference marks 2 and known spatial
relations between the positions of the plurality of surface
electrodes 9 and the positions of the reference marks 2 provided by
a spatial relation providing unit 12.
[0040] Thus, the wand 4 with the optical shape sensing fiber 6 is
used to measure the positions of the reference marks 2 in the
three-dimensional space with respect to the reference patch 7. By
going from one reference mark 2 to another reference mark 2 and
recording the three-dimensional positions, a three-dimensional
distribution of the reference marks 2 and thus, since the spatial
relations between the reference marks 2 and the surface electrodes
9 being connected by tortuous wires 3 are known, the
three-dimensional distribution of the vest electrodes can be
reconstructed. The wand 4 with the optical shape sensing fiber 6,
the spatial relations providing unit 12 and the surface electrodes
positions calculation 13 can therefore be regarded as being
components of a surface electrodes positions determination unit for
determining the positions of a plurality of surface electrodes by
means of optical shape sensing localization.
[0041] The system 1 further comprises an ultrasound unit 22 for
generating an ultrasound signal being indicative of the position of
the cardiac structure within the person 30. The ultrasound signal
is provided to the determination system 11 via the electrical
connection 15. In this embodiment the ultrasound unit is a
transthoracic echo probe 22 for generating an ultrasound signal
representing a three-dimensional ultrasound image of the heart. In
another embodiment the ultrasound unit can also be another probe
like a transesophageal echo probe.
[0042] The ultrasound signal is provided to a cardiac structure
position calculation unit 14 for calculating the position of the
cardiac structure based on the ultrasound signal. In particular,
the cardiac structure calculation unit 14 is adapted to detect the
cardiac structure in the ultrasound image and to calculate the
position of the cardiac structure based on the cardiac structure
detected in the ultrasound image. For instance, the cardiac
structure position calculation unit 14 can be adapted to perform a
segmentation procedure for segmenting the cardiac structure being,
in this embodiment, the epicardial surface, in the ultrasound image
for detecting the cardiac structure. The cardiac structure position
calculation unit can also be adapted to provide an anatomical
cardiac model being an anatomical model of a heart including the
cardiac structure, i.e. in this embodiment including the epicardial
surface, and to adjust the cardiac model to the ultrasound image of
the heart for detecting the cardiac structure. The cardiac model is
preferentially a generalized cardiac model, i.e. a cardiac model
which is, before being adjusted, not specific for a certain person
or animal. It can be determined by, for instance, averaging of
segmented hearts of a group of living beings, which may be
segmented in medical images. In order to allow the cardiac
structure position calculation unit to calculate the position of
the detected cardiac structure, the cardiac structure position
calculation unit 14 further receives an optical shape sensing
signal from the ultrasound unit 22. The ultrasound unit 22 is
equipped with an optical shape sensing sensor 10 for generating the
optical shape sensing signal being indicative of the position of
the ultrasound unit 22, wherein the cardiac structure position
calculation unit 14 is adapted to determine the position of the
ultrasound unit 22 with respect to the position of the reference
patch 7 based on the optical sensing signals received from the
optical shape sensing sensor 10 of the ultrasound unit 22, which is
an optical shape sensing fiber, and from the optical shape sensing
sensor comprising the reference patch 7 and the optical shape
sensing fiber 26 connected to the patch 7. The position of the
cardiac structure, i.e. in this embodiment of the epicardial
surface, is then determined based on the determined
three-dimensional position of the ultrasound unit 22 and the
determined position of the cardiac structure within the ultrasound
image acquired by the ultrasound unit 22.
[0043] Thus, an ultrasound probe 22 with an optical shape sensing
fiber 10 is used to image the cardiac anatomy, wherein the optical
shape sensing fiber 10, which is preferentially embedded in the
ultrasound probe 22, is used to measure the location of the
ultrasound probe 22 with respect to the reference patch 7, thus
ensuring that the location of the cardiac anatomy as imaged by the
ultrasound probe 22 and the positions of the surface electrodes 9
in three-dimensional space are known with respect to each other. In
other words, since in this embodiment the positions of the surface
electrodes 9 and of the epicardial surface are determined with
respect to the same reference being the reference patch 7, the
spatial relation between the surface electrodes 9 and the
epicardial surface is known. In other embodiments, the positions of
the surface electrodes and the position of, for instance, the
epicardial surface can be determined with respect to another
reference. The optical shape sensing sensor 10, the cardiac
structure position calculation unit 14 and the ultrasound unit 22
with the electrical connection 15 for transferring the ultrasound
signal can be regarded as being elements of a cardiac structure
position determination unit for determining a position of a cardiac
structure like the epicardial surface of the person 30.
[0044] The system further comprises a movement determination unit
for determining a movement of the person 30, wherein the surface
electrodes positions calculation unit 13 is adapted to determine
the positions of the plurality of surface electrodes 9 also
depending on the determined movement. The movement determination
unit comprises a further patch 24, a further optical shape sensing
fiber 23 attached to the patch 24 and a movement calculation unit
18. The movement calculation unit 18 receives an optical shape
sensing signal being indicative of the position of the further
patch 24 attached to the vest 8, wherein for providing this optical
shape sensing signal the patch 24 is connected with the optical
shape sensing fiber 23. The movement calculation unit 18 calculates
the position of the patch 24 at different times from the received
optical shape sensing signal, in order to determine the movement of
the person 30.
[0045] One or several optical shape sensing sensors, for instance,
one or several patches with optical shape sensing fibers, can be
used for determining the movement of the person 30. The optical
shape sensing sensors for determining the movement of the person
can be adapted to be directly attached to the person. For instance,
the optical shape sensing sensors, in particular, patches connected
to optical shape sensing fibers, can be put on a person's thorax.
Alternatively or in addition, the optical shape sensing sensors can
be attached to another means being attached to the person. The
other means can be, as shown in FIG. 1, a vest comprising the
plurality of surface electrodes.
[0046] The system 1 further comprises an electrical activity map
determination unit 16 for determining the electrical activity map
at the cardiac structure, i.e. in this embodiment on the epicardial
surface, based on the electrical signals measured on the outer
surface of the person 30, the determined positions of the plurality
of electrodes 9 and the determined position of the cardiac
structure. For determining the electrical activity map well known
methods can be used like the methods disclosed in the article
"Electrocardiographic Imaging (ECGI): A Noninvasive Imaging
Modality for Cardiac Electrophysiology and Arrhythmia" by
Ramanathan et al., Nature Medicine 10, 422-428 (2004) or disclosed
in U.S. Pat. No. 7,471,971, which are herewith incorporated by
reference. Moreover, known products from the companies
CardioInsight Technologies and Amycard can be used for determining
the electrical activity map at the cardiac structure, i.e. in this
embodiment on the epicardial surface, based on the electrical
signals measured on the outer surface of the person, the determined
positions of the plurality of electrodes and the determined
position of the cardiac structure.
[0047] The determination system 11 further comprises an analysis
unit 21 for analyzing the electrical activity map for determining
electrophysiological mechanisms of certain cardiac arrhythmias.
Moreover, in addition or alternatively the analysis unit 21 may be
adapted to analyze the electrical activity behaviour of cardiac
dyssnychrony in heart failure patients as disclosed in the articles
"Noninvasive Characterization of Epicardial Activation in Humans
with Diverse Atrial Fibrillation Patterns" by P. S. Cuculich et
al., Circulation 122, 1364-1372 (2010), "Electrocardiographic
Imaging of Ventricular Bigeminy in a Human Subject" by Y. Wang et
al., Circulation Arrhythmia and Electrophysiology 1, 74-75 (2008)
and "Electrocardiographic Imaging of Cardiac Resynchronization
Therapy in Heart Failure: Observations of Variable
Electrophysiological Responses" by P. Jia et al., Heart Rhythm
Journal 3, 296-310 (2006), which are herewith incorporated by
reference.
[0048] In particular, the analysis unit can be adapted to perform
at least one of following analyses based on the electrical activity
map: determination of an anatomical position of ectopi foci,
determination of an anatomical position of ventricular re-entries,
distinguishing between re-entry or focal ventricular tachycardia
and assessing of its localizations, assessing re-connection of
pulmonary vein conduction and localization of culprit pulmonary
veins, and assessment of effects of antiarrhythmic drugs.
[0049] The electrical activity map of the heart and optionally
results of the analysis can be shown on a display unit 19.
[0050] FIG. 2 shows schematically and exemplarily a further
embodiment of a system for providing an electrical activity map of
the heart of a living being by means of electrical signals from the
heart acquired by a plurality of surface electrodes being arranged
on an outer surface of the living being. Also in this embodiment
the living being is a person 130 wearing a vest 108 with a
plurality of electrodes 109 connected by tortuous wires 103. The
surface electrodes 109 are used for acquiring electrical signals at
the outer surface of the person 130, wherein the acquired
electrical signals are provided to a determination system 111 via
an electrical connection 125.
[0051] The vest 108 comprises an optical shape sensing fiber 107
for providing an optical shape sensing signal being indicative of
the position of each portion of the optical shape sensing fiber 107
within the vest 108. An ultrasound unit 122 with an optical shape
sensing fiber 110 and an electrical connection 115 for providing
ultrasound signals to the determination system 111 is used for
generating a three-dimensional ultrasound image of the heart of the
person 130. The ultrasound unit 122 with the optical shape sensing
fiber 110 and the electrical connection 115 is similar to the
ultrasound unit 22 with the optical shape sensing fiber 10 and the
electrical connection 15 described above with reference to FIG.
1.
[0052] The determination system 111 comprises a spatial relation
providing unit 112 for providing a spatial relation between the
optical shape sensing fiber 107 within the vest 108 and the surface
electrodes 109. This spatial relation is used together with the
optical shape sensing signal, which is provided by the optical
shape sensing fiber 107 and which is indicative of the position of
each portion of the optical shape sensing fiber 107 within the vest
108, for determining the position of the surface electrodes 109
incorporated into the vest 108. Thus, the shape of at least one
optical shape sensing fiber 107, which is embedded in a specific
pattern in the vest 108, can be measured for determining the
position of each portion of the optical shape sensing fiber 107
within the vest 108. The locations of the surface electrodes 109
with respect to the optical shape sensing fiber 107 are known from
the spatial relation provided by the spatial relation providing
unit 112. Therefore, a surface electrodes positions calculation
unit 113 can calculate the three-dimensional distribution of the
surface electrodes 109 by measuring the three-dimensional shape of
the optical fiber 107. The optical shape sensing fiber 107, the
spatial relation providing unit 112 and the surface electrodes
positions calculation unit 113 can therefore be regarded as being
elements of a surface electrodes positions determination unit for
determining positions of the plurality of surface electrodes 109 by
means of optical shape sensing localization.
[0053] The determination system 111 further comprises a cardiac
structure position calculation unit 114 for calculating the
position of the cardiac structure, i.e. in this embodiment of the
epicardial surface, based on the optical shape sensing signal
received from the vest optical shape sensing fiber 107, the optical
shape sensing signal received from the ultrasound optical shape
sensing fiber 110 and the ultrasound signal acquired by the
ultrasound unit 122. In particular, the ultrasound signal is a
three-dimensional ultrasound image of the heart of the person 130,
wherein the cardiac structure position calculation unit 114 is
adapted to segment the epicardial surface in the three-dimensional
ultrasound image for determining the position of the epicardial
surface within this image. The position of this epicardial surface
with respect to the position of the surface electrodes 109 is then
determined by determining the position of the ultrasound unit 122
with respect to the position of the optical shape sensing fiber
107. Thus, the ultrasound unit 122, which can be regarded as being
an ultrasound probe wand, is used to image the cardiac anatomy,
wherein the optical shape sensing fiber 110, which is embedded in
the ultrasound unit 122, is used to measure the location of the
ultrasound unit 122 with respect to the optical shape sensing fiber
107 embedded in the vest 108, thereby ensuring that the location of
the cardiac anatomy, i.e. in this embodiment of the epicardial
surface, as imaged by the ultrasound unit 122 and the position of
the surface electrodes 109 are known in the three-dimensional
space. The optical shape sensing fiber 110, the cardiac structure
calculation determination unit 114 and the ultrasound unit 122 with
the electrical connection 115 for transferring the ultrasound
signals can be regarded as being elements of a cardiac structure
position determination unit for determining a position of a cardiac
structure of the person 130.
[0054] The determination system 111 further comprises an electrical
activity map determination unit 116 and an analysis unit 121, which
are similar to the electrical activity map determination unit 16
and the analysis unit 21, respectively, described above with
reference to FIG. 1. Also the display unit 119 is similar to the
display unit 19 described above with reference to FIG. 1.
[0055] In the following an embodiment of a method for providing an
electrical activity map of the heart of a living being by means of
electrical signals from the heart acquired by a plurality of
surface electrodes at an outer surface of the living being will
exemplarily be described with reference to a flowchart shown in
FIG. 3.
[0056] In step 101, the positions of the plurality of surface
electrodes are determined by the surface electrodes positions
determination unit by means of optical shape sensing localization.
For instance, the wand 4 with the connected optical shape sensing
fiber 6 described above with reference to FIG. 1 is used for
determining the three-dimensional positions of reference marks of a
vest worn by a person by using optical shape sensing. A surface
electrodes positions calculation unit can then calculate the
three-dimensional positions of the electrodes of the vest based on
the determined three-dimensional positions of the reference marks
and provided spatial relations between the reference marks and the
surface electrodes incorporated in the vest. Alternatively, an
optical shape sensing fiber 107 embedded in the vest worn by the
person can be used for determining the three-dimensional position
of the surface electrodes as described above with reference to FIG.
2. In particular, the three-dimensional position of each portion of
the optical shape sensing fiber 107 within the vest 108 can be
determined by optical shape sensing, wherein the surface electrodes
positions calculation unit can calculate the three-dimensional
positions of the surface electrodes based on the determined
three-dimensional position of each portion of the optical shape
sensing fiber 107 within the vest 108 and a provided spatial
relation between the optical shape sensing fiber within the vest
and the surface electrodes embedded in the vest.
[0057] In step 102, the position of a cardiac structure of the
person 30 is determined. In this embodiment the position of the
epicardial surface is determined. For instance, the ultrasound unit
with the optical shape sensing sensor described above with
reference to FIGS. 1 and 2 is used for generating a
three-dimensional ultrasound image showing the epicardial surface,
wherein the cardiac structure position calculation unit can
calculate the three-dimensional position of the epicardial surface
based on, for example, a segmentation of the epicardial surface in
the three-dimensional ultrasound image and the position of the
ultrasound unit determined by optical shape sensing localization.
Steps 101 and 102 can be performed in an arbitrary order, i.e. they
can be performed consecutively or simultaneously.
[0058] In step 103, the electrical activity map determination unit
determines the electrical activity map at the cardiac structure,
i.e., in this embodiment, on the epicardial surface, based on the
electrical signals measured on the outer surface of the person, the
positions of the plurality of surface electrodes determined in step
101 and the position of the cardiac structure determined in step
102. In step 104, the analysis unit analyzes the electrical
activity map, in order to determine, for example,
electrophysiological mechanisms of certain cardiac arrhythmias. In
step 105, the electrical activity map and optionally also results
of the analysis are shown on the display unit.
[0059] In the embodiment of the method for providing an electrical
activity map of the heart described above with reference to FIG. 3
it is assumed that the electrical signals on the outer surface of
the person have been measured already and are provided to the
electrical activity map determination unit for allowing the
electrical activity map determination unit to determine the
electrical activity map. In another embodiment the measurement of
the electrical signals on the outer surface of the person can also
be a part of the method for providing the electrical activity map,
wherein in this case a corresponding electrical signals measurement
step is performed before step 103.
[0060] Electrocardiographic mapping (ECM) is a method where body
surface signals, i.e. electrical signals like electrical potentials
measured at the outer surface of the person, which are measured by
a multitude of electrodes covering the entire human thorax, are
used to calculate the activation of the epicardial surface of the
heart. The electrodes are surface electrodes, i.e. electrodes
measuring electrical signals at the surface of the person, and they
are contained in the vest that is tightly attached to the skin of
the thorax by an adhesive. Alternatively or in addition, the vest
can comprise elastic textiles for tightly fitting the vest to the
skin of the thorax. Since the position of the epicardial heart
surface and the positions of the surface electrodes have been
determined, the three-dimensional spatial relations between the
epicardial heart surface and the surface electrodes are known. This
enables the electrical activity map determination unit to compute
an accurate single beat electrical activation pattern on the
epicardial heart surface being the electrical activity map. The
system described above with reference to FIG. 1 can therefore
provide a non-invasive method for rapid assessment, i.e. within
seconds to real time, of cardiac electrical activation. This
electrocardiographic mapping can be performed, for example, during
an electrophysiological procedure or during interventional
cardiology procedures in a corresponding laboratory. However, the
electrocardiographic mapping can also be performed for
pre-interventional or post-interventional follow-up diagnostic
procedures. In particular, the electrocardiographic mapping can be
used to assess effects of antiarrhythmic drugs at certain points
during a course of drug use and may be used for performing a high
resolution electrocardiographic analysis.
[0061] The systems described above with reference to FIGS. 1 and 2
allow a rapid assessment of the three-dimensional positions of the
vest electrodes, i.e. of the surface electrodes, by means of
optical shape sensing localization and the assessment of the
three-dimensional cardiac anatomy in relation to the
three-dimensional positions of the vest electrodes by means of a
transthoracic or transesophageal echo probe that is localized in
the three-dimensional space by means of optical shape sensing
localization. The systems can be used as an advanced
electrocardiography tool with epicardial activation diagnosis
capabilities.
[0062] Preferentially, the configuration of the electrodes in the
electrocardiography mapping vest within the vest fabric is known.
In an embodiment, in particular in the embodiment described above
with reference to FIG. 1, within the vest are a plurality of
landmark points, i.e. reference marks, that can be visually
identified, for instance, by having a certain color and/or shape.
The positions of electrodes in relation to the landmark points are
known as well. After putting on the vest to the person the
three-dimensional positions of the landmark points can be
determined by touching the landmarks by means of the wand equipped
with the optical shape sensing sensor. The number and distribution
of the landmark points are preferentially such that the relative
positions of all electrodes in relation to the landmarks and
therefore in relation to a frame of reference can be calculated
based on the known positions of the electrodes within the fabric
and in relation to the landmarks. To avoid person motion
distortion, one or more additional optical shape sensing sensors
can be temporally added to the vest or attached to patches that are
put somewhere on the patient's thorax to compensate for the person
movement.
[0063] Preferentially, the ultrasound unit is used for
reconstructing a transthoracic or transesophageal three-dimensional
representation of the person's cardiac anatomy. This reconstruction
can be based on three-dimensional imaging of the heart and
subsequent segmentation of the cardiac structures or by matching a
generalized three-dimensional cardiac model to the
three-dimensional ultrasound image, wherein optionally the
generalized three-dimensional cardiac model can be deformed. The
ultrasound probe is equipped with optical shape sensing
localization as well, thus allowing to correlate the
three-dimensional cardiac anatomy with the vest electrode
positions. In an embodiment the ultrasound based cardiac anatomy
assessment is performed before or after the vest electrodes
positions assessment. In both cases optical shape sensing sensors
temporally added to the vest or attached to a patch that is put
somewhere on the patient's thorax can be used to relate the
ultrasound probe position and therefore the three-dimensional
cardiac anatomy to the vest electrode positions.
[0064] In an embodiment, in particular in the embodiment described
above with reference to FIG. 2, the electrode vest can be equipped
with one or more optical shape sensing fibers, wherein the
positions of the vest electrodes are identified and therefore known
in relation to the one or more optical shape sensing fibers.
Through assessing the three-dimensional shape of the one or more
optical shape sensing fibers the three-dimensional positions of the
vest electrodes can be calculated. Also in this embodiment the
position of the cardiac anatomy is determined as described above by
using an ultrasound probe, wherein in this embodiment the position
of the ultrasound probe is registered with the position of the vest
electrodes by using the optical shape sensing signals from the one
or more optical shape sensing fibers within the vest and from the
optical shape sensing sensor of the ultrasound probe.
[0065] Although in the embodiment described above with reference to
FIG. 1 an additional wand 4 equipped with an optical shape sensing
fiber 6 is used for determining the three-dimensional positions of
reference marks 2, in another embodiment this additional wand 4
with the optical shape sensing fiber 6 is not needed. Instead, the
ultrasound probe 22 can be used for determining the
three-dimensional positions of the reference marks 2. Thus, a user
like a physician can move the ultrasound probe 22 from reference
mark to reference mark, in order to determine the three-dimensional
positions of these reference mark by optical shape sensing
localization. These three-dimensional positions of the reference
marks are then used by the surface electrodes position calculation
unit for determining the three-dimensional positions of the surface
electrodes as described above. The same ultrasound probe 22 can
then be used for providing an ultrasound signal being indicative of
the cardiac structure, in particular, being indicative of the
epicardial surface, in order to determine the position of the
epicardial surface.
[0066] The ultrasound probe is preferentially used through an
opening in the vest directly on the skin of the thorax, or before
the vest is put on by the person. In the embodiment described above
with reference to FIG. 1, the ultrasound probe 22 may be used on
the skin of the thorax for acquiring an ultrasound image of the
heart before the vest is put on by the person, but after a
reference patch being connected to an optical shape sensing fiber
for determining the position of the reference patch is applied to
the skin of the thorax.
[0067] The locations of the surface electrodes of the vest can be
determined by means of Fiber Optic Shape Sensing and Localization
(FOSSL) technology, for example, based on Fiber Bragg Gratings. The
vest may contain one or more fibers with such grating that allow
the full three-dimensional shape and location of the fibers to be
determined. By knowing the spatial relation between each of the
surface electrodes and a relevant fiber, the location of each of
the electrodes can be determined. This can then be realized without
any x-ray or magnetic resonance based localization of the surface
electrodes. Moreover, the ultrasound probe can be a
three-dimensional transesophageal or micro transthoracic ultrasound
probe which can be used to reconstruct the heart. Furthermore, the
FOSSL technology can be used to localize the probe by means of such
a fiber, in particular, in a catheter. The FOSSL technology can be
used to localize the surface electrodes as described above.
[0068] The systems described above with reference to FIGS. 1 and 2
provide an electrocardiographic mapping based on a
three-dimensional assessment of vest electrode positions by means
of optical shape sensing localized vest electrodes and based on a
three-dimensional cardiac anatomy assessment of optical shape
sensing localized ultrasound imaging. The system can therefore
provide an electrocardiographic diagnostic tool that can be used
for obtaining, for instance, pre-interventional and
post-interventional information that is not obtainable by known
electrocardiographic systems. For example, information can be
provided such as reasonably accurate positions of ectopic foci,
reasonable accurate positions of ventricular re-entries,
information that distinguishes between re-entry or focal
ventricular tachycardia and its localizations, information about
re-connection of pulmonary vein conduction and localization of
culprit pulmonary veins, in order to be at least able to
distinguish between left and right pulmonary veins, and information
about effects of antiarrhythmic drugs, in particular, of changes in
use of antiarrhythmics drugs.
[0069] Although in above described embodiments, in particular, in
FIGS. 1 and 2, the vest has a certain distribution of electrodes,
it should be noted that the electrodes in the vest are only
schematically and exemplarily indicated in FIGS. 1 and 2, i.e., for
instance, they can be distributed differently within the vest. The
vest preferentially comprises several hundreds of the electrodes
covering the entire thorax of the person.
[0070] Other variations to the disclosed embodiments can be
understood and effected by those skilled in the art in practicing
the claimed invention, from a study of the drawings, the
disclosure, and the appended claims.
[0071] In the claims, the word "comprising" does not exclude other
elements or steps, and the indefinite article "a" or "an" does not
exclude a plurality.
[0072] A single unit or device may fulfill the functions of several
items recited in the claims. The mere fact that certain measures
are recited in mutually different dependent claims does not
indicate that a combination of these measures cannot be used to
advantage.
[0073] Calculations like the calculation of the surface electrodes
positions, the calculation of the cardiac structure position, the
calculation of the electrical activity map and/or the analysis of
the electrical activity map performed by one or several units or
devices can be performed by any other number of units or devices.
The calculations and/or the analysis of the electrical activity map
and/or the control of the system for providing an electrical
activity map in accordance with the method for providing an
electrical activity map can be implemented as program code means of
a computer program and/or as dedicated hardware.
[0074] A computer program may be stored/distributed on a suitable
medium, such as an optical storage medium or a solid-state medium,
supplied together with or as part of other hardware, but may also
be distributed in other forms, such as via the Internet or other
wired or wireless telecommunication systems.
[0075] Any reference signs in the claims should not be construed as
limiting the scope.
[0076] The invention relates to a system for providing an
electrical activity map of the heart of a living being by means of
electrical signals from the heart acquired by a plurality of
surface electrodes being arranged on an outer surface of the living
being. A surface electrodes positions determination unit determines
positions of the plurality of surface electrodes by means of
optical shape sensing localization and an electrical activity map
determination unit determines the electrical activity map at the
cardiac structure based on the measured electrical signals, the
determined positions of the plurality of electrodes and a position
of a cardiac structure, in particular, of the epicardial surface.
Since optical shape sensing is used for determining the positions
of the plurality of surface electrodes and not, for instance,
x-rays, the electrical activity map can be determined, without
necessarily applying an x-ray radiation dose.
* * * * *