DESCRIPTION
LASER THERAPY APPARATUS, LASER THERAPY SYSTEM, AND
DETERMINATION METHOD
5 Technical Field
[OOOl] The present invention relates to a laser
therapy apparatus that treats a therapy-target tissue
by using a laser catheter, a laser therapy system, and
a determination method that can be applied to the
10 apparatus and the system.
Background Art
[0002] Atrial fibrillation is known as a kind of
tachyarrhythmia. A hyperexcited site, which generates
an electrical pulse, appears in the vicinity of a
15 junction between a pulmonary vein and a left atrium,
and the left atrium minutely vibrates and contracts
because of the electrical pulse stimulation, thereby
causing atrial fibrillation.
[0003] As an atrial fibrillation therapy, the
20 inventors have been proposed application of
photodynamic therapy (hereinafter, referred to as
"PDT". ) (see, for example, Patent Document 1) . In PDT,
a cardiac muscle tissue, which has absorbed a
photosensitive agent, is irradiated with excitation
25 light by using a laser catheter, thereby generating
singlet oxygen. The singlet oxygen having strong
oxidizing power damages a cardiac muscle tissue, which
surrounds the hyperexcited site, thereby forming an
electrical conduction block, which blocks conduction of
the electrical pulse from the hyperexcited site to the
5 left atrium. As a result, electrical conduction between
the hyperexcited site and the left atrium is blocked,
and an abnormal vibration and contraction of the left
. , atrium is inhibited.
[0004] The photosensitive agent has properties of
10 selectively accumulating in a certain tissue. In view
of this, in general, after a predetermined time period
(e.g., 8 to 48 hours) passes after a photosensitive
agent is administered to a patient, when the state
where the concentration of the photosensitive agent is
high in a therapy-target tissue and the concentration
of the photosensitive agent is low in other tissues and
blood is established, i.e., when the state where a socalled
photosensitive agent contrast is high is
established, irradiation with the excitation light is
started. Further, in recent years, PDT in which the
accumulating- properties of the photosensitive agent are
not used and irradiation with the excitation light is
started when the photosensitive agent is delivered to
the therapy-target tissue by blood is proposed.
[0005] In the field of circulatory disease treatment,
in order to ensure safety and reliability, it is
important to determine a contact state between a tip
portion of a laser catheter, which emits excitation
light, and a tissue. In Patent Documents 2 and 3,
techniques for determining the contact state between
5 the tip portion and the tissue are described. In Patent
Document 2, the deformation of the tip portion being in
contact with the tissue is estimated by reflected light,
thereby detecting the contact state between the tip
portion and the tissue. In Patent Document 3, a
10 pressure sensor is provided at the tip portion, thereby
detecting the contact state between the tip portion and
the tissue.
Citation List
Patent Document
15 [0006] Patent Document 1: WO 2008/066126
Patent Document 2: Japanese Unexamined Patent
Application Publication No. 2008-531170 (paragraphs
LO0441 to [0061])
Patent Document 1: Japanese Unexamined Patent
20 Application Publication No. 2009-542371 (paragraph
[0085l)
Disclosure of the Invention
Problem to be solved by the Invention
[0007] According to the findings of the inventors,
25 it turns out that such an excessive pressure as to bury
the tip portion of the laser catheter in the tissue
causes a large burden on a patient during a surgical
operation and is deeply involved in a side effect after
surgery. However, although it is possible to evaluate
the pressure of the tip portion of the laser catheter
5 on the tissue by using the techniques described in
Patent Documents 2 and 3, it is difficult for a
practitioner such as a doctor to recognize the buried
state unless an evaluation standard for a pressure
value in the buried state is provided. Furthermore, the
relationship between the buried state and the pressure
value cannot be uniformly established for all patients,
and it is considered that there is an individual
difference in the relationship. Moreover, in the
techniques described in Patent Documents 2 and 3,
because there is a need to mount a device such as a
pressure sensor, which is not necessary for treatment,
the configuration of the laser catheter is complicated.
[ 0 0 0 8 ] In view of the above-mentioned circumstances,
it is an object of the present invention to provide a
laser therapy apparatus that is capable of determining
a contact state between a tip portion of a laser
catheter and a tissue, which includes a buried state of
the tip portion in the tissue, a laser therapy system,
and a determination method.
Another object of the present invention is to
provide a laser therapy apparatus that is capable of
realizing such determination with a simple
configuration, a laser therapy system, and a
determination method.
Means for solving the Problem
5 [0009] In order to achieve the above-mentioned
object, a laser therapy apparatus according to an
embodiment of the present invention includes a
connection portion, an emission unit, an optical state
detection unit, an electrical state detection unit, and
10 a determination unit.
[OOlO] To the connection portion, a second end
portion of a laser catheter is connected, the laser
catheter including a first end portion, the second end
portion, and an electrode, a laser beam entering and
15 exiting from an apical surface of the first end portion,
the electrode being provided at outer periphery of the
first end portion along an axial direction of the first
end portion.
The emission unit emits a laser beam to the second
20 end portion connected to the connection portion.
The optical state detection unit causes light
reflected from the second end portion connected to the
connection portion to enter, and detects an optical
state of the entered reflected light.
25 The electrical state detection unit detects an
electrical state of the electrode via the second end
portion connected to the connection portion.
[OOll] The determination unit determines, based on
the detected optical state and electrical state, a
contact state between the first end portion and a
therapy-target tissue treated by using the laser
catheter.
[OOlZ] Here, in the present invention, the optical
state detection unit may detect an intensity of the
entered reflected light, the electrical state detection
unit may detect a potential of the electrode, and the
determination unit may determine that the contact state
between the first end portion and the therapy-target
tissue is normal in the case where the detected
intensity of light is low and the detected potential' is
low, determine that the first end portion is buried in
the therapy-target tissue.in the case where'the
detected intensity of light is low and the detected
potential is high, and determine that the laser
catheter is in contact with the therapy-target tissue
therealong in the case where the detected intensity of
light is high and the detected potential is high.
[0013 1 In the present invention, it is possible to
determine a contact state between a tip portion (first
end portion) of a laser catheter and a tissue, which
includes a buried state of the tip portion in the
tissue by detecting an optical state of light reflected
from the laser catheter and detecting an electrical
state of an electrode provided at outer periphery of
the first end portion of the laser catheter along an
axial direction of the first end portion. Moreover, the
5 electrode is originally used for treatment, and there
is no need to mount a device such as a pressure sensor,
which is not necessary for treatment. Therefore, it is
possible to realize determination of the contact state,
which includes the buried state, with a simple
10 configuration.
A laser therapy system according to an embodiment
of the present invention includes a laser catheter, a
connection portion, an emission unit, an optical state
detection unit, an electrical state detection unit, and
15 a determination unit.
[0014] The laser catheter includes a first end
portion, a laser beam entering and exiting from an
apical surface of the first end portion, a second end
portion, and an electrode provided at outer periphery
20 of the first end portion along an axial direction of
the first end portion.
To the connection portion, the second end portion
of the laser catheter is connected.
The emission unit emits a laser beam to the second
25 end portion connected to the connection portion.
The optical state detection unit causes light
reflected from the second end portion connected to the
connection portion to enter, and detects an optical
state of the entered reflected light.
The electrical state detection unit detects an
5 electrical state of the electrode via the second end
portion connected to the connection portion.
[0015] The determination unit determines, based on
the detected optical state and electrical state, a
contact state between the first end portion and a
10 therapy-target tissue treated by using the laser
catheter.
Here, the electrode provided on the laser catheter
may include a ring electrode.
[0016] A determination method according to an
15 embodiment of the present invention includes emitting a
laser beam to a second end portion of a laser catheter,
the laser catheter including a first end portion, the
second end portion, and an electrode, a laser beam
entering and exiting from an apical surface of the
20 first end portion, the electrode being provided at
outer periphery of the first end portion along an axial
direction of the first end portion, causing light
reflected from the second end portion to enter, and
detecting an optical state of the entered reflected
25 light, detecting an electrical state of the electrode,
and determining, based on the detected optical state
and electrical state, a contact state between the first
end portion and a therapy-target tissue treated by
using the laser catheter.
Effect of the Invention
5 [0017] In the present invention, it is possible to
determine a contact state between a tip portion of a
laser catheter and a tissue, which includes a buried
state of the tip portion in the tissue. Moreover, it is
possible to realize determination of the contact state,
10 which includes the buried state, with a simple
configuration.
Brief Description of Drawings
[0018]
[Fig. 11 A schematic diagram showing the entire system
15 including a PDT apparatus according to an embodiment of
the present invention.
[Fig. 21 A schematic diagram showing a laser catheter
inserted in a heart.
[Fig. 31 A block diagram showing a configuration of
20 the PDT apparatus.
. [Fig. 41 A diagram showing a diagram showing the
appearance of the laser catheter.
[Fig. 51 A partial cross-sectional view of a tip
portion of the laser catheter shown in Fig. 4.
25 [Fig. 61 A cross-sectional view taken along the line
A-A in Fig. 5.
[Fig. 71 A schematic diagram showing a contact state
between the tip portion of the laser catheter and a
tissue.
[Fig. 81 A table showing a relationship between a
fluorescence intensity and potential and the contact
state.
Mode(s) for Carrying Out the Invention
[0019] Hereinafter, embodiments according 'to the
present invention will be described with reference to
10 the drawings. In the embodiments, a description will be
given using, as a laser apparatus, a photodynamic
therapy apparatus (hereinafter referred to as "PDT
apparatus") .
[Configuration of Entire System]
Fig. 1 is a schematic diagram showing the entire
therapy system including a PDT apparatus according to
an embodiment of the present invention.
[0020] A PDT apparatus 1 includes a PDT apparatus
main body 100, a tube 200 connected to the PDT
20 apparatus main body 100, and a connector (connection
portion) 210 provided at the tip of the tube 200.
[00211 , The tube 200 is a soft hollow tube, and is
capable of transmitting light through a built-in
apparatus-attached optical fiber 201 (see Fig. 3).
25 Moreover, through a built-in apparatus-attached
electrical wiring 202 (see Fig. 3), it is possible to,
for example, measure a potential in the tip portion of
a laser catheter 300.
To the connector 210, the laser catheter 300 is
detachably connected.
[0022] To a patient 2, a photosensitive agent is
administered. In the case of being administered by
intravenous injection, the administered photosensitive
agent diffuses in the blood, and then diffuses in a
tissue such as a cardiac muscle tissue. A dose of
photosensitive agent necessary for treatment may be
administered at one time by intravenous injection, may
be continuously administered by intravenous drip, may
be administered at one time or continuously via the
oral route, or may be locally administered. The
photosensitive agent is an agent that is excited by
absorbing light having a certain wavelength, and emits
fluorescence. Examples of the photosensitive agent
include an agent called talaporfin sodium (Laserphyrin
(registered trademark), Meiji Seika Kaisha Ltd.).
Because the Q-band absorption wavelength of the agent
is near 664 nm, an excitation light source for the
agent with, for example, 600 to 800 nm, favorably 660
to 680 nm, or more favorably 664 plus or minus 2 nm is
used.
Fig. 2 is a schematic diagram showing a laser
catheter inserted in a heart.
[0023] The laser catheter 300 is inserted in a right
atrium 14 of a heart 10 through a femoral vein or a
jugular vein of the patient 2. The laser catheter 300,
which has reached the right atrium 14, penetrates a
5 septum, and is led to a left atrium 13.
[Configuration of PDT Apparatus Main Body]
Fig. 3 is a block diagram showing the PDT
apparatus main body.
[0024] The PDT apparatus main body 100 includes a
10 light source 110, an optical system 120, an optical
state detection unit 130, a potential detection unit
135, an electrocardiograph 140, a control unit 150, a
storage unit 160, a display unit 170, and an operating
unit 180.
15 [0025] The light source 110 outputs excitation light
of a photosensitive agent. The wavelength of the light
output by the light source 110 is the same as the Qband
absorption wavelength of the photosensitive agent.
For example, in the case where a photosensitive agent
20 whose Q-band absorption wavelength is near 664 nm is
used, a semiconductor laser with the oscillation
wavelength of 600 to 800 nm, favorably 660 to 680 nm,
or more favorably 664 plus or minus 2 nm is used as the
light source 110. The excitation light (laser light)
25 output by the light source 110 enters the laser
catheter 300 via the optical system 120.
COO261 The optical system 120 causes the excitation
light, which is emitted from the light source 110, to
enter the laser catheter 300, which is connected to the
connector 210 through the apparatus-attached optical
5 fiber 201. The optical system 120 extracts, from the
laser catheter 300, fluorescence (reflected light)
emitted from a photosensitive agent, which is
irradiated with the excitation light, and causes the
fluorescence to enter the optical state detection unit
10 130. The optical system 120 includes a short pass
filter 121, a first lens 122, a polarizing beam
splitter (hereinafter referred to as "PBS". ) 123, a
long pass filter 124, and a second lens 125.
[0027] The short pass filter 121 is a short-
15 ' wavelength transmission filter with a cut-on wavelength
of 670 nm, and cuts long-wavelength radiation of a
laser beam. The excitation light from the light source
110 has a radiation component in the fluorescence
observation wavelength range (long-wavelength side of
20 peak wavelength). In view of the above, the radiation
component of the excitation light on the longwavelength
side is cut at the stage prior to collecting
the light in the laser catheter 300. The excitation
light, which has been transmitted through the short
25 pass filter 121, enters the first lens 122.
COO281 The first lens 122 collects the excitation
light, which has entered from the short pass filter 121,
on an end surface of the laser catheter 300. Further,
the first lens 122 collects fluorescence from the tip
portion of the laser catheter 300 on the PBS 123. It
5 should be noted that a part of the excitation light
from the light source 110 is reflected on an end
surface of the apparatus-attached optical fiber 201 at
the PDT apparatus main body 100 side, on the inside of
the connector 210, and on the tip portion of the laser
10 catheter 300, and enters the PBS 123 as specular
reflection light. The specular reflection light is
noisy when detecting fluorescence.
[0029] By using polarization differences, the PBS
123 causes the specular reflection light, which has
15 reflected on an end surface of the optical fiber in the
tube 200, out of the light having entered from the
first lens 122, to transmit therethrough, does not
detect the specular reflection light, reflects the
fluorescence and the specular reflection light
20 reflected on the other end surfaces, and leads them to
a detector. The fluorescence, which has been
transmitted through the PBS 123, enters the long pass
filter 124.
[0030] The long pass filter 124 causes the specular
25 reflection light, which has reflected on the inside of
the connector 210 and the tip portion of the laser
I?
catheter 300, out of the light having entered from the
PBS 123, not to transmit therethrough, causes only the
fluorescence to transmit therethrough, and leads the
fluorescence to the detector. The fluorescence, which
has been transmitted through the long pass filter 124,
enters the second lens 125.
The second lens 125 collects the fluorescence,
which has entered from the long pass filter 124, on the
optical state detection unit 130.
10 [0031] The optical state detection unit 130 is, for
example, a linear image sensor, and spectroscopically
detects the fluorescence having entered from the
optical system 120. That is, the optical state
detection unit 130 detects the light having the
15 excitation wavelength, and detects the fluorescence of
the photosensitive agent, which is light having a
wavelength longer than the excitation wavelength. The
optical state detection unit 130 outputs, as an
electrical signal, an intensity of the detected
20 fluorescence to the control unit 150.
[0032] The potential detection unit 135 detects the
potential of a second electrode (to be described later)
with respect to a Zirst electrode on the tip portion of
the laser catheter 300. The potential detection unit
25 135 output, as an electrical signal, the detected
potential to the control unit 150.
[0033] To the electrocardiograph 140, an electrode
pad 141 is connected via an electrode code (not shown).
The ele.ctrocardiograph 140 obtains an
electrocardiographic signal of the patient 2 via the
5 electrode pad 141, which is attached to the patient 2,
and via the electrode code, and supplies the obtained
electrocardiographic signal to the control unit 150.
The control unit 150 controls the respective units
of the PDT apparatus 1.
10 [0034] The control unit 150 determines a contact
state between the laser catheter 300 and a tissue,
which includes a buried state of the laser catheter 300
in the tissue, based on the electrical signal obtained
from the optical state detection unit 130 and the
15 potential detection unit 135.
[0035] The control unit 150 determines whether or
not an electrical conduction block is formed based on
the electrical signal obtained from the optical state
detection unit 130 and the electrocardiographic signal
20 obtained from the electrocardiograph 140.
The control unit150 outputs a display instruction
to display information of the determination result of
the contact state including the buried state.
The storage unit 160 is a non-volatile memory, and
25 is set in, for example, a flash memory, an HDD (Hard
Disk Drive), or another solid memory.
[0036] The display unit 170 is a display device,
which uses, for example, a liquid-crystal display
device. When obtaining a display instruction from the
control unit 150, the display unit 170 displays, on a
5 display screen, for example, information of the
determination result of the contact state including the
buried state, based on display information included in
the display instruction.
[0037] The operating unit 180 receives an
10 instruction by an input operation from a practitioner,
and outputs the received instruction to the control
unit 150. Examples of the instruction include an
instruction to turn on/off the excitation light output
from the light source 110, and an instruction to change
15 the intensity. As the intensity of the excitation light,
it is possible to select at least one of two levels of
intensity including a first intensity, which has a low
power (e.g., optical output of 1 mW or less) and is
minimally-invasive with respect to a tissue and blood,
20 and a second intensity, which has a high power and is
approximately 1,000 times higher than the first
intensity. The first intensity is selected when
monitoring the agent concentration and the contact
state of the laser catheter 300 before treatment. The
25 second intensity is selected when treatment is actually
performed.
I".
[Configuration of Laser Catheter]
Fig. 4 is a diagram showing the appearance of the
laser catheter, Fig. 5 is a partial cross-sectional
view of a tip portion of the laser catheter shown in
Fig. 4, and Fig. 6 is a cross-sectional view taken
along the line A-A in Fig. 5.
[ 0 0 3 8 1 The laser catheter 300 emits excitation light
from an end surface of the tip portion (first end
portion). The laser catheter 300 includes a catheter
tube 310, a first end portion 311, a second end portion
312, a holding portion 320, an optical fiber 330, an
optical window 340, a plurality of electrodes 351 and
352, and a wiring 353.
[0039] The catheter tube 310 is a soft hollow tube,
and is led to the inner wall of a cardiac muscle tissue
of the heart 10 of the patient 2. The catheter tube 310
has the optical fiber 330 and the wiring 353 therein.
The catheter tube 310 includes the first end portion
311 and the second end portion 312 at both ends thereof.
[0040] The holding portion 320 is provided on the
first end portion 311 of the laser catheter 300. The
holding portion 320 holds the optical fiber 330 and the
optical window 340 with respect to the catheter tube
310. At the outer periphery of the holding portion 320
being the first end portion 311 along the axial
direction (X direction in Fig. 4), the plurality of
electrodes 351 and 352 are provided so as to have a
predetermined space t between them. The plurality of
electrodes' 351 and 352 include Pt (platinum) and have a
ring shape, for example. Out of the plurality of
5 electrodes 351 and 352, the electrode 351 is'located at
the edge portion of the holding portion 320, for
example. The electrode 351 may cover an end surface of
the holding portion 320. Conversely, the electrode 351
may be located so as to have a small space between the
10 electrode 351 and the edge portion of the holding
portion 320. For example, out of the plurality of
electrodes 351 and 352, the electrode 351 has a width
wider than the electrode 352, and the space t between
the plurality of electrodes 351 and 352 is
15 approximately 2 mm. The space t between the plurality
of electrodes 351 and 352 and other dimensions may be
variable as long as the change in potential of the
second electrode with respect to the first electrode
when the plurality of electrodes 351 and 352 are
20 brought into contact with a tissue can be detected. The
plurality of electrodes 351 and 352 are brought into
contact with a tissue when the first end portion 311 of
the laser catheter 300 is buried in the tissue.
[0041] The plurality of electrodes 351 and 352 are
25 connected to the apparatus-attached electrical wiring
202 at the second end portion 312 via the respective
wirings 353, and connected to the potential detection
unit 135 of the PDT apparatus main body 100. For
example, the potential detection unit 135 detects
potential information of a cardiac muscle tissue from
5 an electrode, which is brought into contact with the
cardiac muscle tissue. Further, the potential detection
unit 135 may detect the potential difference between
the pair of the electrodes 351 and 352 by applying
predetermined voltage to the electrode 351, and
10 detecting the potential of the electrode 352. In the
case where the electrode 352 is not in contact with the
tissue, the detected potential of the electrode 352 is
low, and in the case where the electrode 352 is not in
contact with the tissue, the detected potential of the
electrode 352 is high.
[0042] The optical fiber 330 is, for example, one
quartz step index fiber having a core diameter of 133
pm and an outside diameter of 500 pm or having a core
diameter of 200 pm and an outside diameter of 350 pm.
The optical fiber 330 transmits the excitation light
from the PDT apparatus 1. The optical fiber 330 emits
the transmitted excitation light, as an irradiation
light 301, from the tip to the optical window 340. The
beam diameter of the irradiation light 301 increases
with the angle determined by the numerical aperture
(NA) of the optical fiber 330. The tip of the optical
fiber 330 is processed so that the beam diameter of the
irradiation light 301 appropriately increases. The
optical fiber 330 transmits the fluorescence, which is
emitted from a photosensitive agent absorbed in a
5 tissue and irradiated with excitation light, to the PDT
apparatus 1.
[004 3 j The optical window 340 is provided on the
outermost of the tip portion of the laser catheter 300
so that the optical window 340 is optically connected
10 to the tip of the optical fiber 330. The optical window
340 includes a solid transparent material, e . g . , a
glass material such as BK7. The optical window 340
causes the irradiation light 301, which is output from
the tip of the optical fiber 330, to transmit
15 therethrough. The optical window 340 collects the
fluorescence, which is emitted from the photosensitive
agent, on the tip of the optical fiber 330.
[Operation of PDT Apparatus]
Next, an operation of the PDT apparatus 1
20 configured as described above will be described.
The operation of the PDT apparatus 1 will be
described in the following order.
(1) Preparation for PDT
(2) Contact-Monitoring Operation
25 [0044] In the contact-monitoring operation, the
light source 110 outputs excitation light with the
first intensity, and the control unit 150 determines a
contact state between the laser catheter 300 and an
inner wall of a tissue, which includes a buried state
of the laser catheter 300 in the inner wall of the
5 tissue based on the fluorescence intensity detected by
the optical state detection unit 130 and the potential
detected by the potential detection unit 135.
(3) Laser Therapy Performing Operation
[0045] In the laser therapy performing operation,
10 the light source 110 outputs the excitation light with
the second intensity, and laser therapy is actually
performed. Also in the operation, as in the contactmonitoring
operation, the contact state between the
laser catheter 300 and the inner wall of the tissue,
15 which includes the buried state of the laser catheter
300 in the inner wall of the tissue, is determined.
In the following, the operations are described in
more detail.
[ (1) Preparation for PDT]
20 LO0461 First, a practitioner such as a doctor
inserts the laser catheter 300 in the heart 10 through
a femoral vein or a jugular vein of the patient 2. The
tip portion of the laser catheter 300 is disposed in
the vicinity of a pulmonary vein 12 of an inner wall of
25 a cardiac muscle tissue 11 of the left atrium 13 (see
Fig. 2 ) .
Subsequently, with reference to various types of
reference data, the practitioner administers a
photosensitive agent to the patient 2.
[ ( 2 ) Contact-Monitoring Operation]
Subsequently, the contact-monitoring operation is
performed.
Fig. 7 is a schematic diagram showing a contact
state of a laser catheter.
[00471 The laser catheter 300 is desirably disposed
10 such that the tip portion (first end portion) as a
light-emitting portion is vertically brought into
contact with the inner wall of the cardiac muscle
tissue 11 (see Fig. 7(a), hereinafter referred to as
"vertical contact state".). This is because an intra-
15 atrial blood 15 is removed from the tip portion of the
laser catheter 300, and activation of a photosensitive
agent in the intra-atrial blood 15 is suppressed.
Further, this is because the photo-sensitive agent
absorbed in a tissue is selectively activated by
20 directly bringing the tip portion of the laser catheter
300 into contact with the tissue.
[00481 However, actually, the tip portion of the
laser catheter 300 is not vertically but obliquely, as
shown in Fig. 7(b), brought into contact with the inner
25 wall of the cardiac muscle tissue 11 in some cases. As
shown in Fig. 7(c), the tip portion of the laser
catheter 300 is buried in the inner wall of the cardiac
muscle tissue 11 in some cases. Moreover, as shown in
Fig. 7(d), the tip portion of the laser catheter 300 is
obliquely buried in the inner wall of the cardiac
5 muscle tissue 11 in some cases. As shown in Fig. 7(e),
the tip portion of the laser catheter 300 is not even
brought into contact with the inner wall of the cardiac
muscle tissue 11 in some cases.
[0049] In particular, as shown in Fig. 7(c) and 7 (d),
10 in the case where the tip portion of the laser catheter
300 is buried in the inner wall of the cardiac muscle
tissue 11, the tip portion of the laser catheter 300 is
excessively pressed onto the inner wall of the cardiac
muscle tissue 11. Such an excessive pressure causes a
15 large burden on a patient during a surgical operation
and is deeply involved in a side effect after surgery.
In view of the above, in the contact-monitoring
operation according to this embodiment, the control
unit 150 determines a contact state between the laser
20 catheter 300 and an inner wall of a tissue, which
includes a buried state of the laser catheter 300 in
the inner wall of the tissue based on the fluorescence
intensity detected by the optical state detection unit
130 and the potential detected by the potential
25 detection unit 135.
Fig. 8 is a table showing a relationship between a
detected fluorescent intensity and potential and the
contact state shown in Fig. 7 (a) to (e) .
[0050] As shown in Fig. 7 (a), in the case where the
tip portion of the laser catheter 300 is vertically
brought into contact with the inner wall of the cardiac
muscle tissue 11, blood (having agent-c oncentration
higher than the tissue) between the tip portion and the
inner wall of the cardiac muscle tissue 11 is almost
removed. Therefore, the fluorescence intensity detected
10 by the optical state detection unit 130 is low. In this
case, because the electrode 352 is not in contact with
the tissue, the potential of the electrode 352 detected
by the potential detection unit 135 is low.
[0051] As shown in Fig. 7(b), in the case where the
15 tip portion of the laser catheter 300 is obliquely
brought into contact with the inner wall of the cardiac
muscle tissue 11, a small amount of blood lies between
the tip portion and the inner wall of the cardiac
muscle tissue 11. Therefore, the fluorescence intensity
20 detected by the optical state detection unit 130 is
middle. In this case, because the electrode 352 is not
in contact with the tissue, the potential of the
electrode 352 detected by the potential detection unit
135 is low.
25 [0052] As shown in Fig. 7 (c), in the case where the
tip portion of the laser catheter 300 is vertically
buried in the inrier wall of the cardiac muscle tissue
11, blood between the tip portion and the inner wall of
the cardiac muscle tissue 11 is almost removed.
Therefore, the fluorescence intensity detected by the
5 optical state detection unit 130 is low. In this case,
because the electrode 352 is in contact with the tissue,
the potential of the electrode 352 detected by the
potential detection unit 135 is high.
[0053] As shown in Fig. 7(d), in the case where the
10 tip portion of the laser catheter 300 is obliquely
buried in the inner wall of the cardiac muscle tissue
11, blood between the tip portion and the inner wall of
the cardiac muscle tissue 11 is almost removed.
Therefore, the fluorescence intensity detected by the
15 optical state detection unit 130 is low. In this case,
because the electrode 352 is slightly in contact with
the tissue, the potential of the electrode 352 detected
by the potential detection unit 135 is middle to high.
[0054] In any case, in the case where the tip
20 portion of the laser catheter 300 is buried in the
inner wall of the cardiac muscle tissue 11, the
potential of the electrode 352 detected by the
potential detection unit 135 is not low. Therefore, it
is possible to determine the buried state by detecting
25 that the potential of the electrode 352 is not low by
the potential detection unit 135.
[0055] As shown in Fig. 7(e), in the case where the
tip portion of the laser catheter 300 is not in contact
with the inner wall of the cardiac muscle tissue 11,
blood lies at the tip portion in almost all cases.
5 Therefore, the fluorescence intensity detected by the
optical state detection unit 130 is high. In this case,
in the case where the electrode 352 is in contact with
the tissue, the potential of the electrode 352 detected
by the potential detection unit 135 is high, and in the
10 case where the electrode 352 is slightly in contact
with the tissue, the potential of the electrode 352
detected by the potential detection unit 135 is low. In
any case, in the case where the tip portion of the
laser catheter 300 is not in contact with the inner
15 wall of the cardiac muscle tissue 11, the fluorescence
intensity detected by the optical state detection unit
130 is high. Therefore, it is possible to determine the
contact state of the catheter, which is in contact with
the cardiac muscle tissue therealong, by detecting that
20 the fluorescence intensity is high by the optical state
detection unit 130. Moreover, by using only the
information from the potential detection unit 135, it
is difficult to understand the difference between the
state of (e) (state where the electrode 352 is in
25 contact with the cardiac muscle tissue) and the states
of (c) and (d) . However, by combining information of
the fluorescence intensity, it is poss-ible to determine
the state of the tip portion.
[0056] Based on the electrical signal obtained from
the optical state detection unit 130 and the potential
5 detection unit 135, the control unit 150 determines the
contact state between the laser catheter 300 and the
tissue, which includes the buried state of the laser
catheter 300 in the tissue, i.e., which state shown in
Fig. 7 (a) to (e) the laser catheter 300 is in. For
10 example, in the case where the laser catheter 300 is in
any one of the states shown in Fig. 7(c) to (e), the
control unit 150 displays a predetermined warning on
the display unit 170. At this time, the control unit
150 may display the warning so as to distinguish Fig.
15 7 (c) and (d) , and Fig. 7 (e) . Accordingly, a
practitioner such as a doctor can recognize that the
laser catheter 300 is in the buried state, and an
excessive pressure on the cardiac muscle tissue can be
alleviated. Therefore, a side effect can be reduced,
20 which leads to reduction of a burden on a patient.
Further, it is possible to prevent an effect on the
surrounding organs. It should be noted that the
practitioner such as a doctor may be notified of the
warning by not display on the display unit but by a
25 predetermined alarm sound. The practitioner operates a
handpiece or the like (not shown) provided on the laser
catheter 300, thereby changing the contact state
between the tip portion of the laser catheter 300 and
the tissue.
[(3) Laser Therapy Performing Operation]
5 [0057] The practitioner operates the operating unit
180, thereby inputting an excitation-light-output
instruction with the high-power second intensity to the
control unit 150. When obtaining the excitation-lightoutput
instruction, the control unit 150 outputs the
10 excitation-light-output instruction with the second
intensity to the light source 110. When obtaining the
excitation-light-output instruction from the control
unit 150, the light source 110 outputs the excitation
light with the second intensity. A tissue is irradiated
15 with the excitation light output from the light source
110 via the optical system 120 and the laser catheter
300. Thus, photodynamic therapy is performed.
[0058] Also in the operation, as in the contactmonitoring
operation, a contact state between the laser
20 catheter 300 and an inner wall of a tissue, which
includes a buried state of the laser catheter 300 in
the inner wall of the tissue, is determined. That is,
the control unit 150 determines the contact state
between the laser catheter 300 and the tissue, which
25 includes the buried state of the laser catheter 300 in
the tissue, i.e., which state shown in Fig. 7 (a) to (e)
the laser catheter 300 is in, based on the electrical
signal obtained from the optical state detection unit
130 and the potential detection unit 135. The control
unit 150 displays a predetermined warning on the
5 display unit 170. Accordingly, similarly to the above,
a practitioner such as a doctor can recognize that the
laser catheter 300 is in the buried state, and an
excessive pressure on the cardiac muscle tissue can be
alleviated.
10 [0059] In this embodiment, the plurality of
electrodes 351 and 352 are originally used for
treatment (e.g., simple treatment effect and
determination of the contact state), and there is no
need to mount a device such as a pressure sensor, which
15 is not necessary for treatment. Therefore, it is
possible to realize determination of the contact state,
which includes the buried state, with a simple
configuration.
Embodiments according to the present invention are
20 not limited to the above-mentioned embodiments and
various modifications can be made.
[0060] In the above-mentioned embodiment, the laser
catheter 300 is detachably connected to the connector
210 of the PDT apparatus 1. However, the laser catheter
25 300 may be integrally provided on the PDT apparatus 1.
[0061] In the above-mentioned embodiment, the tube
200 is provided on the PDT apparatus main body 100, and
the connector 210 is provided at the tip of the tube
200. However, the connector 210 may be provided on the
PDT apparatus main body 100.
5 In the above-mentioned embodiment, a fluorescence
intensity has been described as an exemplary optical
state to be detected. However, as the optical state,
for example, a difference in a diffuse reflection light
intensity (of excitation light) of a tissue and blood
10 may be used.
In the above-mentioned embodiment, a potential has
been described as an exemplary electrical state to be
detected. However, as the electrical state, for example,
resistance may be used.
15 In the above-mentioned embodiment, the two
electrodes 351 and 352 have been described as an
example, one electrode or three or more electrodes may
be used.
In the above-mentioned embodiment, an electrode
20 having a ring shape has been described as an example.
However, the electrode may have a pectinate shape or a
sawtooth shape.
Description of Reference Numerals
[0062]
25 1 photodynamic therapy (PDT) apparatus
100 PDT apparatus main body
110 light source (emission unit)
130 optical state detection unit
135 potential detection unit (electrical state
detection unit)
5 150 contro1,unit (determination unit)
210 connector (connection portion)
300 laser catheter
311 first end portion
312 second end portion
10 351,352 electrode

Claims
[I] A laser therapy apparatus, comprising:
a connection portion to which a second end portion
of a laser catheter is connected, the laser catheter
including a first end portion, the second end portion,
and an electrode, a laser beam entering and exiting
from an apical surface of the first end portion, the
electrode being provided at outer periphery of the
first end portion along an axial direction of the first
end portion;
an emission unit configured to emit a laser beam
to the second end portion connected to the connection
portion;
an optical state detection unit configured
to cause light reflected from the second end
portion connected to the connection portion to enter,
and
to detect an optical state of the entered
reflected light;
an electrical state detection unit configured to
detect an electrical state of the electrode via the
second end portion connected to the connection portion;
and
a determination unit configured to determine,
based on the detected optical state and electrical
state, a contact state between the first end portion
and a therapy-target tissue treated by using the laser
catheter.
[2] The laser therapy apparatus according to claim 1,
wherein
5 the optical state detection unit is configured to
detect an intensity of the entered reflected light,
the electrical state detection unit is configured
to detect a potential of the electrode, and
the determination unit is configured
10 to determine that the contact state between
the first end portion and the therapy-target tissue is
normal in the case where the detected intensity of
light is low and the detected potential is low,
to determine that the first end portion is
15 buried in the therapy-target tissue in the case where
the detected intensity of light is low and the detected
potential is high, and
to determine that the laser catheter is in
contact with the therapy-target tissue therealong in
the case where the detected intensity of light is high
and the detected potential is high.
[31 A laser therapy system, comprising:
a laser catheter including
a first end portion, a laser beam entering
and exiting from an apical surface of the first end
portion
a second end portion, and
an electrode provided at outer periphery of
the first end portion along an axial direction of the
first end portion;
5 a connection portion to which the second end
portion of the laser catheter is connec.ted;
an emission unit configured to emit a laser beam
to the second end portion connected to the connection
portion;
10 an optical state detection unit configured
to cause light reflected from the second end
portion connected to the connection portion to enter,
and
to detect an optical state of the entered
15 reflected light;
an electrical state detection unit configured to
detect an electrical state of the electrode via the
second end portion connected to the connection portion;
and
a determination unit configured to determine,
based on the detected optical state and electrical
state, a contact state between the first end portion
and a therapy-target tissue treated by using the laser
catheter.
[4] The laser therapy system according to claim 3,
, .I
wherein
' 8
~ ~ 3 1 4 4 7 0 ~ 0 0 0 ~
the electrode provided on the laser catheter is a
ring electrode. -
1 --
151 A determination method, comprising :
emitting a laser beam t.0 a second end portion of a
laser catheter, the laser catheter including a first
end portion, the second end portion, and an electrode,* *
a laser beam entering and exiting from an.apical 4&
surface of the first end portion, the electrode being
provided at outer periphery of the first end portion
- 10 an axial airection of the first end portion;
causing light reflected from the second end
portion to enter, and detecting an optical .state of the
entered reflected light;
detecting an electrical state of the electrode;
15 and
determining, based on the detected optical state
and electrical state, a contact state between the first
end Portion and a therapy-target tissue treated by
L
using the laser catheter.
20
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Dated this 12/07/20 13 w (RANJNA MEHTA-DUTT)
OF REMFRY & SAGA^
ATTORNEY FOR THE APPLICANT[§]