Ablation catheter device, ablation catheter, and heating element

Abstract

To provide an ablation catheter device that can be handled more easily.SOLUTION: An ablation catheter device ACD includes: a heating element HE fixed to one end of an optical fiber OF; a light source LS connected to the other end of the optical fiber OF; a light reception element PD for receiving radiant light RL emitted by the heating element HE; and a control part CTR for controlling the temperature of the heating element HE. The light reception element PD detects the intensity of the radiant light RL emitted by the heating element HE through the optical fiber OF. The control part CTR adjusts the intensity of irradiation light IL emitted by the light source LS on the basis of data on the intensity of the radiant light RL output by the light reception element PD, and controls the temperature of the heating element HE. The heating element HE has a plurality of resonant wavelengths by localized surface plasmon resonance, generates heat by receiving the irradiation light IL having a wavelength corresponding to one of the plurality of resonant wavelengths, and emits the radiant light RL having a wavelength corresponding to another of the plurality of resonant wavelengths.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to an ablation catheter device, an ablation catheter, and a heating element. [Background technology]

[0002] Conventionally, ablation catheter devices are known for use in catheter ablation (catheter cauterization), a procedure that uses an ablation catheter to cauterize specific tissues inside a patient's body (see Patent Document 1). This device can treat the affected area by passing a high-frequency current between the tip of the ablation catheter and a counter electrode plate placed outside the body, thereby causing coagulation and necrosis of the specific tissue in contact with the tip of the ablation catheter. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-325916 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, because the above-mentioned device uses high-frequency current, it may be difficult for practitioners and others to handle.

[0005] Therefore, it is desirable to provide an ablation catheter device that is easier to use. [Means for solving the problem]

[0006] An ablation catheter apparatus according to an embodiment of the present disclosure comprises an optical fiber, a heating element fixed to one end of the optical fiber, a light source connected to the other end of the optical fiber, a light receiving element that receives radiant light emitted by the heating element, and a control unit that controls the temperature of the heating element. ,beforeThe heating element has multiple resonant wavelengths due to localized surface plasmon resonance, and has a wavelength corresponding to one of the multiple resonant wavelengths. ru teru It generates heat when exposed to sunlight, When the predetermined temperature is reached It is configured to emit radiation light having a wavelength corresponding to another one of the plurality of resonant wavelengths. The light-receiving element detects the intensity of the radiated light emitted by the heating element through the optical fiber, and the control unit adjusts the intensity of the irradiated light emitted by the light source based on the data regarding the intensity of the radiated light output by the light-receiving element to control the temperature of the heating element. . [Effects of the Invention]

[0007] The above-described method can provide a more user-friendly ablation catheter device. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an example of the configuration of an ablation catheter device. [Figure 2] This is a diagram showing a heating element attached to the tip of an ablation catheter. [Figure 3] This is a partial cross-sectional view of the heating element attached to the tip of the ablation catheter. [Figure 4] These are a rear view and a cross-sectional view of a portion of the heating element. [Figure 5] This graph shows the relationship between the wavenumber of the irradiated light and the reflectivity of the heating element relative to the irradiated light. [Figure 6] This is a schematic diagram showing a part of the heating element. [Figure 7] This graph shows an example of the relationship between the pattern size of the first conductor and the resonant wavelength. [Figure 8] This is a rear view of a part of the heating element. [Figure 9] This graph shows the relationship between the wavenumber of the irradiated light and the reflectivity of the heating element relative to the irradiated light. [Figure 10] This figure shows another example of a heating element configuration. [Figure 11] This figure shows yet another example of a heating element configuration. [Figure 12] This figure shows yet another example of a heating element configuration. [Modes for carrying out the invention]

[0009] First, referring to FIGS. 1 and 2, a configuration example of an ablation catheter device ACD according to an embodiment of the present disclosure will be described. FIG. 1 is a schematic diagram showing a configuration example of the ablation catheter device ACD. FIG. 2 is a view of a heating element HE attached to the tip of an ablation catheter CA as a disposable medical instrument (disposable product) used in the ablation catheter device ACD.

[0010] In FIG. 2, X1 represents one direction of the X-axis constituting a three-dimensional orthogonal coordinate system, and X2 represents the other direction of the X-axis. Y1 represents one direction of the Y-axis constituting a three-dimensional orthogonal coordinate system, and Y2 represents the other direction of the Y-axis. Z1 represents one direction of the Z-axis constituting a three-dimensional orthogonal coordinate system, and Z2 represents the other direction of the Z-axis. In FIG. 2, the X1 side of the heating element HE corresponds to the front side (front face side) of the heating element HE, and the X2 side of the heating element HE corresponds to the rear side (rear face side) of the heating element HE. Also, the Y1 side of the heating element HE corresponds to the left side of the heating element HE, and the Y2 side of the heating element HE corresponds to the right side of the heating element HE. Similarly, the Z1 side of the heating element HE corresponds to the upper side of the heating element HE, and the Z2 side of the heating element HE corresponds to the lower side of the heating element HE. The same applies to other figures.

[0011] Specifically, the upper left figure in FIG. 2 is a right side view of the tip of the ablation catheter CA and corresponds to an enlarged view of the range R1 surrounded by the dashed line in FIG. 1. The upper right figure in FIG. 2 is a front view of the tip of the ablation catheter CA, and the lower figure in FIG. 2 is a cross-sectional view of the tip of the ablation catheter CA. More specifically, the lower figure in FIG. 2 shows a cross-section of the tip of the ablation catheter CA in a virtual plane parallel to the XZ plane including the cutting line CL1 shown in the upper right figure in FIG. 2. In FIG. 2, for clarity, the optical fiber OF constituting the ablation catheter CA is shown in a simplified manner, and the illustration of the core, cladding, coating material, etc. of the optical fiber OF is omitted. Also, in FIG. 2, for clarity, some members constituting the heating element HE are exaggerated and are different from the actual dimensions.

[0012] As shown in FIG. 1, an ablation catheter device ACD includes a flexible optical fiber OF, a heating element HE fixed to one end of the optical fiber OF, a light source LS connected to the other end of the optical fiber OF, a light receiving element PD that receives the radiation light RL emitted by the heating element HE, and a control unit CTR that controls the temperature of the heating element HE.

[0013] The optical fiber OF is a transmission path for transmitting light. In the illustrated example, the optical fiber OF includes a first optical fiber OF1, a second optical fiber OF2, and a third optical fiber OF3. The heating element HE is fixed to one end of the first optical fiber OF1, and an optical circulator OC is connected to the other end of the first optical fiber OF1. The optical circulator OC is connected to one end of the second optical fiber OF2, and the light source LS is connected to the other end of the second optical fiber OF2. The optical circulator OC is connected to one end of the third optical fiber OF3, and the light receiving element PD is connected to the other end of the third optical fiber OF3.

[0014] The optical circulator OC is a device used when transmitting light using the optical fiber OF. In the illustrated example, the optical circulator OC is configured to emit the light (irradiation light IL) incident from the light source LS toward the heating element HE, and to emit the light (radiation light RL) incident from the heating element HE toward the light receiving element PD. In other words, the optical circulator OC is configured not to emit the light (irradiation light IL) incident from the light source LS toward the light receiving element PD, and not to emit the light (radiation light RL) incident from the heating element HE toward the light source LS.

[0015] The light source LS is configured to output light of any intensity. In the illustrated example, the intensity of the light output by the light source LS is adjusted according to a control command from the control unit CTR. The light source LS is configured to output infrared rays. Note that the light source LS may be configured to output light other than infrared rays, such as microwaves, visible light, or ultraviolet rays.

[0016] The light-receiving element PD is configured to detect the intensity of the received light. In the illustrated example, the light-receiving element PD is configured to detect the brightness (intensity) of the radiant light emitted by the heat-generating element HE. The light-receiving element PD may also be configured to detect both the brightness (intensity) and color (wavelength) of the radiant light emitted by the heat-generating element HE.

[0017] The control unit CTR is configured to control the temperature of the heat-generating element HE by adjusting the intensity of the irradiation light IL emitted by the light source LS based on data regarding the intensity of the radiated light RL output by the photodetector PD. In the illustrated example, the control unit CTR is a microcomputer having a CPU, a volatile memory device, and a non-volatile memory device, and is connected to both the light source LS and the photodetector PD. The control unit CTR is configured to calculate the temperature of the heat-generating element HE from the intensity of the radiated light detected by the photodetector PD, and to output an output reduction command to the light source LS if the calculated temperature is higher than a predetermined temperature (e.g., 400K), and to output an output increase command to the light source LS if the calculated temperature is lower than the predetermined temperature (e.g., 400K). This is to maintain the temperature of the heat-generating element HE at a predetermined temperature (e.g., 400K).

[0018] The heating element HE has multiple resonant wavelengths due to localized surface plasmon resonance, and is configured to generate heat when exposed to irradiation light IL having a wavelength corresponding to one of the multiple resonant wavelengths, and to emit radiation light RL having a wavelength corresponding to another of the multiple resonant wavelengths.

[0019] "Surface plasmon resonance" refers to the phenomenon or collective vibration of electrons in a reflector, whether solid or liquid, when it reflects light, due to the incident light (irradiation light IL). The wavelength of the incident light (irradiation light IL) at this time is called the "resonance wavelength." Surface plasmon resonance in a microscopic structure is called "localized surface plasmon resonance." In this embodiment, the heating element HE is configured to have two resonance wavelengths due to localized surface plasmon resonance in a metamaterial structure, which is a microscopic structure such as a nanometer or micrometer size.

[0020] In the illustrated example, the heating element HE has a layered structure consisting of a first conductor M1 that determines one of the two resonant wavelengths, a second conductor M2 that determines the other of the two resonant wavelengths, a third conductor M3, and a dielectric DE, as shown in the lower part of Figure 2.

[0021] The first conductor M1 and the second conductor M2 are components or layers that absorb light (infrared light) that satisfies the resonance conditions for surface plasmon resonance, thereby generating surface plasmon resonance. When the first conductor M1 and the second conductor M2 are irradiated with irradiation light IL (infrared light), plasmon vibrations of free electrons are excited on the surfaces of the first conductor M1 and the second conductor M2, respectively. The irradiation light IL may be light other than infrared light. When plasmon vibrations are excited, the density of free electrons is generated inside the first conductor M1 and the second conductor M2, respectively, and the inside of the first conductor M1 and the second conductor M2 becomes polarized. The method of forming the first conductor M1 and the second conductor M2 is not particularly limited as long as it can generate surface plasmon resonance, and they can be formed, for example, by known semiconductor manufacturing techniques such as photolithography. Furthermore, the materials of the first conductor M1 and the second conductor M2 are not particularly limited as long as they can induce surface plasmon resonance, and for example, they may be composed of one or more of the following: gold, silver, copper, platinum, aluminum, or palladium.

[0022] The dielectric DE is a component or layer provided between the first conductor M1 and the second conductor M2 and the third conductor M3, causing surface plasmon resonance in each of the first conductor M1 and the second conductor M2. The method of forming the dielectric DE is not particularly limited as long as it can cause surface plasmon resonance in each of the first conductor M1 and the second conductor M2, and can be formed by known film deposition techniques such as resistance heating deposition, sputtering, electron beam deposition, and spin coating. Furthermore, the material of the dielectric DE is not particularly limited as long as it can cause surface plasmon resonance in each of the first conductor M1 and the second conductor M2, and can be composed of one or more of the following: silicon oxide, aluminum oxide, silicon nitride, silicon, zirconium oxide, titanium oxide, etc.

[0023] The third conductor M3 is a component or layer that, when laminated with the first conductor M1 and the second conductor M2 via a dielectric DE, causes or enhances surface plasmon resonance in the first conductor M1 and the second conductor M2, respectively. The method of forming the third conductor M3 is not particularly limited as long as it can cause surface plasmon resonance, and can be formed by known film deposition techniques such as resistance heating deposition, sputtering, or electron beam deposition. Furthermore, the material of the third conductor M3 is not particularly limited as long as it can cause surface plasmon resonance, and can be composed of one or more of the following: gold, silver, copper, platinum, aluminum, or palladium.

[0024] Specifically, as shown in Figure 2, the heating element HE is configured such that a plurality of first conductors M1 and a plurality of second conductors M2, each having a minute external shape, are arranged on the rear side (X2 side) of the dielectric DE, which has a roughly disc-shaped external shape. In other words, the heating element HE is configured such that the first conductors M1 and the second conductors M2 are spaced apart from each other on the rear side (X2 side) of the dielectric DE, which is the side that is struck by the irradiation light IL transmitted by the optical fiber OF.

[0025] Furthermore, the heating element HE is configured such that a third conductor M3, having a roughly disc-shaped outer form, is positioned in front of the dielectric DE (on the X1 side). In other words, the heating element HE is configured so that the front surface of the third conductor M3 directly contacts the affected area. Note that another component that directly contacts the affected area may be attached to the third conductor M3.

[0026] Next, with reference to Figure 3, the method by which the ablation catheter device ACD heats the heating element HE will be explained. Each figure in Figure 3 is a partial cross-sectional view of the heating element HE attached to the tip of the ablation catheter CA, and corresponds to an enlarged view of the area R2 enclosed by the dashed line in the lower part of Figure 2. Specifically, as indicated by the arrows, Figure 3 shows how the state of the heating element HE changes in the order of the upper left, left center, lower left, upper right, right center, and lower right figures. Note that in Figure 3, for clarity, the cross-sections of the first conductor M1, dielectric DE, and third conductor M3 do not have hatching patterns to represent the cross-sections. On the other hand, in Figure 3, to make the explanation easier to understand, the positively charged parts of the cross-sections of the first conductor M1 and third conductor M3 are marked with a cross pattern, and the negatively charged parts are marked with a coarse dot pattern. Also, in the lower right figure of Figure 3, the heated parts of the cross-sections of the first conductor M1, dielectric DE, and third conductor M3 are marked with a fine dot pattern.

[0027] More specifically, as shown in the upper left diagram, when the irradiation light IL emitted from the light source LS strikes the rear (X2 side) surface of the first conductor M1, surface plasmon resonance is excited on the surface of the first conductor M1. The irradiation light IL is light having a wavelength corresponding to one of the two resonance wavelengths.

[0028] When surface plasmon resonance is excited, the first conductor M1 develops positively charged and negatively charged regions, as shown in the left center figure. The charge distribution thus generated in the first conductor M1 induces a charge distribution with opposite polarity in the third conductor M3, which is positioned opposite the first conductor M1 across the dielectric DE. The lower left figure shows the state when the lower (Z2 side) portion of the first conductor M1 is positively charged and the upper (Z1 side) portion is negatively charged, resulting in the portion of the third conductor M3 opposite the lower (Z2 side) portion of the first conductor M1 being negatively charged, and the portion of the third conductor M3 opposite the upper (Z1 side) portion of the first conductor M1 being positively charged.

[0029] Subsequently, the first conductor M1 and the third conductor M3, where charge distributions exist, attempt to emit light, as shown in the upper right diagram. Specifically, the first conductor M1 attempts to emit light LT1, indicated by the dotted line, and the third conductor M3 attempts to emit light LT3, indicated by the dashed line. In this case, if light LT1 and light LT3 are in opposite phases, they cancel each other out.

[0030] The central right diagram shows a state where light LT1 and light LT3 cancel each other out, so although the irradiation light IL is incident on the first conductor M1, almost no light is emitted from the first conductor M1.

[0031] As a result, the heating element HE generates heat upon receiving the irradiated light IL. In the lower right diagram, the heat HT transferred to the heating element HE by the irradiated light IL, i.e., the heat HT generated in the heating element HE, is represented by a fine dot pattern.

[0032] Next, with reference to Figures 4 and 5, the relationship between the wavenumber of the irradiated light IL and the reflectance of the first conductor M1 to the irradiated light IL will be explained. Figure 4 shows a part of the heating element HE. Specifically, the upper part of Figure 4 is a rear view of a part of the heating element HE, showing a portion of the rear side (X2 side) of the heating element HE, and the lower part of Figure 4 shows a cross-section of the heating element HE in a virtual plane parallel to the XY plane containing the cutting line CL2 of the upper part of Figure 4. Figure 5 is a graph showing the relationship between the wavenumber of the irradiated light IL and the reflectance of the heating element HE (first conductor M1) to the irradiated light IL. Specifically, Figure 5 is a graph showing the relationship between the wavenumber of the irradiated light IL measured by a Fourier Transform Infrared Spectroscopy (FT-IR) and the reflectance of the first conductor M1 to the irradiated light IL. Also, Figure 5 shows the wavenumber [cm²], which is the number of waves per unit length. -1 The horizontal axis represents the wavenumber, and the vertical axis represents the reflectance [%], which is the ratio of the intensity of reflected light to the incident light (irradiated light IL). Note that the wavenumber corresponds to the reciprocal of the wavelength.

[0033] As shown in the upper diagram of Figure 4, the heating element HE includes a first conductor M1 arranged at equal intervals in the Y-axis and Z-axis directions on the dielectric DE, and a second conductor M2 arranged at equal intervals in the Y-axis and Z-axis directions on the dielectric DE. Furthermore, the first conductor M1 and the second conductor M2 are arranged alternately at equal intervals in a diagonal direction on the dielectric DE.

[0034] When surface plasmon resonance is excited on the surface of the first conductor M1, the laminated structure composed of the first conductor M1, the dielectric DE, and the third conductor M3 exhibits characteristics represented by the equivalent circuit shown in the lower part of Figure 4. In the equivalent circuit, Cm represents the capacitance between the first conductor M1 and the third conductor M3, Rk1 represents the electrical resistance of the first conductor M1, Rk3 represents the electrical resistance of the third conductor M3, Lk1 represents the dynamic inductance of the first conductor M1, Lk3 represents the dynamic inductance of the third conductor M3, Lm1 represents the mutual inductance of the first conductor M1, and Lm3 represents the mutual inductance of the third conductor M3.

[0035] Figure 5 shows the resonance wavelength, approximately 1430 cm[cm]. -1 This indicates that when the irradiated light IL having the wavenumber of ] is incident on the first conductor M1, the reflectance is approximately 10 [%]. This is because the light source LS is approximately 1430 [cm²]. -1 When the irradiating light IL, which has a wavenumber of ], is emitted, it means that most of the energy of the irradiating light IL is absorbed by the heat source HE and converted into heat to heat the heat source HE. In other words, the light source LS is 2000 [cm² -1 ], or 1000[cm -1 ] approximately 1430 [cm -1 Compared to emitting light with a wavenumber other than the resonant wavelength, emitting light with a wavenumber corresponding to the resonant wavelength allows for more efficient heating of the heat-generating element (HE).

[0036] Furthermore, according to Kirchhoff's laws, the smaller the reflectivity, the larger the emissivity. Emissivity is the ratio of the energy of light emitted by an object at a specific temperature through thermal radiation to the energy of light emitted by a black body at a specific temperature (blackbody radiation). This means that the heat source HE can efficiently emit radiation RL with a wavenumber corresponding to the resonant wavelength, compared to radiation RL with a wavenumber other than that corresponding to the resonant wavelength. Also, according to Planck's law, the intensity of radiation RL emitted by the heat source HE increases as the temperature of the heat source HE increases. Therefore, the photodetector PD can efficiently receive radiation RL from the heat source HE with a wavenumber corresponding to the resonant wavelength, and the control unit CTR can estimate the temperature of the heat source HE based on the intensity of the radiation detected by the photodetector PD.

[0037] Next, with reference to Figures 6 and 7, an example of the relationship between the pattern size of the first conductor M1 and the resonant wavelength will be explained. Figure 6 is a schematic diagram showing a part of the heating element HE, and Figure 7 is a graph showing an example of the relationship between the pattern size of the first conductor M1 and the resonant wavelength.

[0038] Specifically, the upper part of Figure 6 is a perspective view of a portion of a heating element HE, showing a section of the heating element HE containing two of several first conductors M1 arranged at equal intervals in the Z-axis direction on a dielectric DE. More specifically, the upper part of Figure 6 shows that the first conductors M1 have a width dimension W1, a length dimension L1, and a height dimension H1, and that the pattern pitch P1 corresponds to the distance between the centers of the two first conductors M1. In the illustrated example, the width dimension W1, length dimension L1, and height dimension H1 of the first conductor M1 are 500 [nm], 500 [nm], and 50 [nm], respectively, and the pattern pitch P1 is 1000 [nm]. That is, the first conductors M1 are typically formed to be thinner than the respective wavelengths of the irradiation light IL and the radiation light RL.

[0039] Furthermore, the lower part of Figure 6 shows an equivalent circuit representing the characteristics realized by the two first conductors M1, the dielectric DE, and the third conductor M3. In this equivalent circuit, Cm represents the capacitance between the first conductor M1 and the third conductor M3, Cg represents the capacitance between two adjacent first conductors M1, Lk1 represents the dynamic inductance of the first conductor M1, Lm1 represents the mutual inductance of the first conductor M1, Lk3 represents the dynamic inductance of the third conductor M3, and Lm3 represents the mutual inductance of the third conductor M3. Note that the electrical resistances of the first conductor M1 and the third conductor M3 are not shown in this equivalent circuit.

[0040] Figure 7 shows the side length [nm] as the pattern size of the first conductor M1 on the horizontal axis and the resonant wavelength [nm] on the vertical axis. The side length [nm] as the pattern size of the first conductor M1 corresponds to the width dimension W1 and length dimension L1 of the first conductor M1, respectively. Figure 7 also shows the resonant wavelength [nm] when the side length is 100 [nm], 200 [nm], 300 [nm], 400 [nm], and 500 [nm] as circular dots. A side length of 100 [nm] means that the width dimension W1, length dimension L1, and height dimension H1 of the first conductor M1 are 100 [nm], 100 [nm], and 50 [nm], respectively, and the pattern pitch P1 is 1000 nm. Furthermore, a side length of 200 nm means that the width W1, length L1, and height H1 of the first conductor M1 are 200 nm, 200 nm, and 50 nm, respectively, and the pattern pitch P1 is 1000 nm. The same applies when the side length is 300 nm or 400 nm.

[0041] Figure 7 shows that if the height dimension H1 and pattern pitch P1 of the first conductor M1 remain constant at 50 nm and 1000 nm, respectively, the resonance wavelength increases as the side length increases.

[0042] The above explanation, with reference to Figures 6 and 7, concerns the relationship between the pattern size and the resonant wavelength of the first conductor M1, which has a square shape when viewed from above. However, the point that the resonant wavelength increases with increasing pattern size also applies to the first conductor M1 having shapes other than a square, such as a circle, ellipse, or polygon. Furthermore, when the first conductor M1 has a circular shape, "side length" is replaced with "diameter." The same applies to the second conductor M2, which is placed on the dielectric DE separately from the first conductor M1.

[0043] Thus, one of the resonant wavelengths of the heating element HE is determined by the pattern size of the first conductor M1, and can be set to a desired value by changing the pattern size of the first conductor M1. The same applies to the other resonant wavelength of the heating element HE, which is determined by the pattern size of the second conductor M2.

[0044] Next, with reference to Figures 8 and 9, an example configuration of a heating element HE having two resonant wavelengths will be described. Figure 8 is a rear view of a portion of the heating element HE, showing a part of the rear (X2 side) surface. Specifically, the upper part of Figure 8 is a rear view of a portion of the heating element HE having a first resonant wavelength and a second resonant wavelength, the middle part of Figure 8 is a rear view of a portion of the heating element HE1 having the first resonant wavelength, and the lower part of Figure 8 is a rear view of a portion of the heating element HE2 having the second resonant wavelength. Figure 9 is a graph showing the relationship between the wavenumber of the irradiated light IL and the reflectance of the back surfaces of the heating elements HE, HE1, and HE2 with respect to the irradiated light IL. Specifically, Figure 9 is a graph showing the relationship between the wavenumber of the irradiated light IL measured by a Fourier transform infrared spectrophotometer and the reflectance of the back surfaces of the heating elements HE, HE1, and HE2 with respect to the irradiated light IL. Figure 9 shows the wavenumber [cm²], which is the number of waves per unit length. -1 The horizontal axis represents the wavenumber, and the vertical axis represents the reflectance [%], which is the intensity ratio of reflected light to incident light (irradiated light IL). Note that the wavenumber corresponds to the reciprocal of the wavelength. Specifically, the dashed line TL1 in Figure 9 represents the relationship between the wavenumber of the irradiated light IL and the reflectance of the back surface of the heating element HE1 with respect to the irradiated light IL, the dashed line TL2 in Figure 9 represents the relationship between the wavenumber of the irradiated light IL and the reflectance of the back surface of the heating element HE2 with respect to the irradiated light IL, and the solid line TL3 in Figure 9 represents the relationship between the wavenumber of the irradiated light IL and the reflectance of the back surface of the heating element HE with respect to the irradiated light IL.

[0045] As shown in the upper part of Figure 8, the heating element HE has a plurality of first conductors M1 formed such that the shape of the rear (X2 side) surface is a circle with diameter D1, and a plurality of second conductors M2 formed such that the shape of the rear (X2 side) surface is a circle with diameter D2, which is larger than diameter D1. The heating element HE is configured such that the pattern pitch P1, which is the distance between the centers of two adjacent first conductors M1, and the pattern pitch P2, which is the distance between the centers of two adjacent second conductors M2, are the same in both the Y-axis and Z-axis directions. Furthermore, the heating element HE is configured such that the pattern pitch P3, which is the distance between the centers of adjacent first conductors M1 and second conductors M2 in the diagonal direction, is smaller than the pattern pitches P1 and P2. In the example shown in the upper part of Figure 8, the diameter D1 is 1.25 [μm], the diameter D2 is 2.50 [μm], and the pattern pitches P1 and P2 are 5.00 [μm].

[0046] As shown in the center diagram of Figure 8, the heating element HE1 has only a plurality of first conductors M1 formed such that the shape of the rear (X2 side) surface is a circle with diameter D1. In other words, the heating element HE1 does not have a second conductor M2. Furthermore, the heating element HE1 is configured such that the pattern pitch P11, which is the distance between the centers of two adjacent first conductors M1 in both the Y-axis and Z-axis directions, is smaller than the pattern pitch P1 in the upper diagram of Figure 8. In the example shown in the center diagram of Figure 8, the pattern pitch P11 is 2.50 [μm].

[0047] As shown in the lower part of Figure 8, the heating element HE2 has only a plurality of second conductors M2 formed such that the shape of the rear (X2 side) surface is a circle with diameter D2. In other words, the heating element HE2 does not have a first conductor M1. Furthermore, the heating element HE2 is configured such that the pattern pitch P12, which is the distance between the centers of two adjacent second conductors M2 in both the Y-axis and Z-axis directions, is the same as the pattern pitch P1 in the upper part of Figure 8. In the example shown in the lower part of Figure 8, the pattern pitch P12 is 5.00 [μm].

[0048] As described above, the heating element HE having the first resonance wavelength and the second resonance wavelength is realized by combining the heating element HE1 having the first resonance wavelength and the heating element HE2 having the second resonance wavelength.

[0049] In the example shown in FIG. 9, the first resonance wavelength is a wavelength corresponding to a wave number of about 6667 [cm -1 , and the second resonance wavelength is a wavelength corresponding to a wave number of about 1000 [cm -1 . The heating element HE is configured to generate heat upon receiving irradiation light IL having a wavelength corresponding to the first resonance wavelength, which is one of the two resonance wavelengths, and emit radiation light RL having a wavelength corresponding to the second resonance wavelength, which is the other one of the two resonance wavelengths. In this case, the first resonance wavelength is smaller than the second resonance wavelength. However, the first resonance wavelength may be larger than the second resonance wavelength.

[0050] Next, referring to FIG. 10, a heating element HEa, which is another configuration example of the heating element HE, will be described. FIG. 10 is a view showing a part of the heating element HEa and corresponds to FIG. 4. Specifically, the upper figure in FIG. 10 is a rear view of a part of the heating element HEa showing a part of the surface on the rear side (X2 side) of the heating element HEa, and the lower figure in FIG. 10 shows a cross-section of a part of the heating element HEa in a virtual plane perpendicular to the YZ plane including the cutting line CL3 of the upper figure in FIG. 10.

[0051] More specifically, the heating element HEa is different from the heating element HE in that each of the first conductor M1 and the second conductor M2 has a rectangular outer shape in a top view, while each of the first conductor M1 and the second conductor M2 has a circular outer shape in a top view in the heating element HE, but is the same as the heating element HE in other respects. Therefore, in the following, the description of the common parts will be omitted, and the different parts will be described in detail.

[0052] The heating element HEa comprises a plurality of first conductors M1 formed such that the shape of the rear (X2 side) surface is a square with sides of length L11, and a plurality of second conductors M2 formed such that the shape of the rear (X2 side) surface is a square with sides of length L12. The heating element HEa is configured such that the pattern pitch P1, which is the distance between the centers of two adjacent first conductors M1, and the pattern pitch P2, which is the distance between the centers of two adjacent second conductors M2, are the same in both the Y-axis and Z-axis directions. Furthermore, the heating element HEa is configured such that the pattern pitch P3, which is the distance between the centers of adjacent first conductors M1 and second conductors M2 in the diagonal direction, is smaller than both the pattern pitch P1 and the pattern pitch P2. In the illustrated example, the first conductors M1 and second conductors M2 have the same height dimension H11, but they may have different height dimensions.

[0053] The configuration shown in Figure 10, similar to the heating element HE, results in the heating element HEa having two resonant wavelengths. This configuration allows the heating element HEa to efficiently generate heat when exposed to irradiation light IL having a wavelength corresponding to the first resonant wavelength, and to efficiently emit radiation light RL having a wavelength corresponding to the second resonant wavelength.

[0054] Next, referring to Figure 11, we will describe another configuration example of the heating element HE, which is the heating element HEb. Figure 11 is a diagram showing a part of the heating element HEb, corresponding to Figures 4 and 10, respectively. Specifically, the upper part of Figure 11 is a rear view of a part of the heating element HEb, showing a part of the rear side (X2 side) of the heating element HEb, and the lower part of Figure 11 shows a cross-section of a part of the heating element HEb in a virtual plane perpendicular to the YZ plane containing the cutting line CL4 of the upper part of Figure 11.

[0055] More specifically, the heating element HEb differs from the heating element HE, in that the first conductor M1 and the second conductor M2 are integrated to form a composite conductor M12, whereas the first conductor M1 and the second conductor M2 are formed separately. In other respects, it is the same as the heating element HE. Therefore, the explanation of the common parts will be omitted below, and the differences will be explained in detail.

[0056] The heating element HEb includes a plurality of composite conductors M12. The composite conductor M12 includes a portion constituting a first conductor M1 and a portion constituting a second conductor M2. The portion constituting the first conductor M1 is formed such that the shape of the rear side (X2 side) is a rectangle having a short side of length dimension LG1 and a long side of length dimension LG2. Similarly, the portion constituting the second conductor M2 is formed such that the shape of the rear side (X2 side) is a rectangle having a short side of length dimension LG11 and a long side of length dimension LG12. That is, the central portion (the portion with the cross pattern) of the rear side (X2 side) of the roughly cross-shaped composite conductor M12, which is a rectangle having a short side of length dimension LG1 and a long side of length dimension LG11, is configured to be both a part of the first conductor M1 and a part of the second conductor M2. Furthermore, the heating element HEb is configured such that the pattern pitch P21, which is the distance between the centers of two adjacent composite conductors M12 in the Y-axis direction, is smaller than the pattern pitch P22, which is the distance between the centers of two adjacent composite conductors M12 in the Z-axis direction. In addition, the heating element HEa is configured such that the pattern pitch P23, which is the distance between the centers of two adjacent composite conductors M12 in the diagonal direction, is larger than the pattern pitch P21 and smaller than the pattern pitch P22. In the illustrated example, the first conductor M1 and the second conductor M2 have the same height dimension H21, but they may have different height dimensions.

[0057] The configuration shown in Figure 11, similar to the HE heating element, results in the effect that the HEb heating element can have two resonant wavelengths. This configuration allows the HEb heating element to efficiently generate heat when exposed to irradiation light IL having a wavelength corresponding to the first resonant wavelength, and to efficiently emit radiation light RL having a wavelength corresponding to the second resonant wavelength.

[0058] Next, referring to Figure 12, we will describe another configuration example of the heating element HE, which is heating element HEc. Figure 12 is a diagram showing a part of heating element HEc, and corresponds to Figures 4, 10, and 11, respectively. Specifically, the upper part of Figure 12 is a rear view of a part of heating element HEc, showing a part of the rear side (X2 side) of heating element HEc, and the lower part of Figure 12 shows a cross-section of a part of heating element HEc in a virtual plane perpendicular to the YZ plane containing the cutting line CL5 of the upper part of Figure 12.

[0059] More specifically, the heating element HEc differs from the heating element HE, which does not have a dielectric between the first conductor M1 and the second conductor M2, in that a dielectric DE (first dielectric DE1) is placed between the first conductor M1 and the second conductor M2. In other respects, it is the same as the heating element HE. Therefore, the explanation of the common parts will be omitted below, and the differences will be explained in detail.

[0060] The heating element HEc includes a first conductor M1 formed such that the shape of its rear (X2 side) surface is circular with a diameter DM1, and a second conductor M2 formed such that the shape of its rear (X2 side) surface is circular with a diameter DM2. A first dielectric DE1 having the same diameter DM2 as the second conductor M2 is placed between the first conductor M1 and the second conductor M2. The heating element HEc is configured such that the pattern pitch P1, which is the distance between the centers of two adjacent first conductors M1, and the pattern pitch P2, which is the distance between the centers of two adjacent second conductors M2, are the same in both the Y-axis and Z-axis directions. Furthermore, the heating element HEc is configured such that the pattern pitch P3, which is the distance between the centers of adjacent first conductors M1 and second conductors M2 in the diagonal direction, is greater than both the pattern pitch P1 and the pattern pitch P2. In the illustrated example, the first conductor M1 and the second conductor M2 have the same height dimension H31, but they may have different height dimensions. Similarly, the first dielectric DE1 and the second dielectric DE2 may have the same height dimension H41, but may also have different height dimensions from each other.

[0061] The configuration shown in Figure 12, similar to the HE heating element, results in the effect that the HEc heating element can have two resonant wavelengths. This configuration allows the HEc heating element to efficiently generate heat when exposed to irradiation light IL having a wavelength corresponding to the first resonant wavelength, and to efficiently emit radiation light RL having a wavelength corresponding to the second resonant wavelength.

[0062] As described above, the ablation catheter apparatus ACD according to the embodiment of this disclosure, as shown in Figure 1, includes an optical fiber OF, a heating element HE fixed to one end of the optical fiber OF, a light source LS connected to the other end of the optical fiber OF, a photodetector PD that receives radiant light RL emitted by the heating element HE, and a control unit CTR that controls the temperature of the heating element HE. Specifically, the photodetector PD is configured to detect the intensity of radiant light RL emitted by the heating element HE through the optical fiber OF. The control unit CTR is configured to control the temperature of the heating element HE by adjusting the intensity of light (irradiation light IL) emitted by the light source LS based on data regarding the intensity of radiant light RL output by the photodetector PD. The heating element HE has multiple resonance wavelengths due to localized surface plasmon resonance, and is configured to generate heat when it receives light (irradiation light IL) having a wavelength corresponding to one of the multiple resonance wavelengths, and emits radiant light RL having a wavelength corresponding to another of the multiple resonance wavelengths. In the illustrated example, the heating element HE has a first resonance wavelength (approximately 1.5 [μm]) and a second resonance wavelength (approximately 10 [μm]) due to localized surface plasmon resonance. It is configured to generate heat upon receiving irradiation light IL having the first resonance wavelength and emit radiated light RL having the second resonance wavelength. The irradiation light IL having the first resonance wavelength may be visible light. The second resonance wavelength is preferably 8 [μm] to 12 [μm].

[0063] Furthermore, the ablation catheter CA according to the embodiment of this disclosure is configured to include an optical fiber OF and a heating element HE fixed to the tip of the optical fiber OF. The heating element HE has multiple resonance wavelengths due to localized surface plasmon resonance, and is configured to generate heat when it receives light (irradiation light IL) having a wavelength corresponding to one of the multiple resonance wavelengths, and to emit radiation light RL having a wavelength corresponding to another of the multiple resonance wavelengths. In the illustrated example, the ablation catheter CA is a disposable product, attached to the ablation catheter device ACD before catheter ablation is performed, and removed from the ablation catheter device ACD and discarded after the catheter ablation is completed.

[0064] Furthermore, the heating element HE according to the embodiment of this disclosure is configured to have a plurality of resonance wavelengths due to localized surface plasmon resonance. Specifically, as shown in Figure 2, the heating element HE comprises a first conductor M1 that determines one of the plurality of resonance wavelengths, a second conductor M2 that determines another of the plurality of resonance wavelengths, a third conductor M3, and an insulator (dielectric DE) provided between the third conductor M3 and the first conductor M1 and the second conductor M2, respectively, so that the first conductor M1 and the second conductor M2 are electrically insulated. In the illustrated example, the heating element HE is a member fixed to the tip of an optical fiber OF, and includes a first conductor M1, a second conductor M2, and a third conductor M3 made of metal, and an insulator (dielectric DE) made of silicon dioxide.

[0065] These configurations offer the advantage of providing an ACD ablation catheter device that is easier to handle than ablation catheter devices using high-frequency current. This is because it can suppress the occurrence of at least one of the various problems that may be caused by ablation catheter devices using high-frequency current.

[0066] Specifically, ablation catheter devices that use high-frequency current are typically used in catheter ablation. Catheter ablation is a treatment method that suppresses the transmission of electrical signals between the pulmonary veins and the left atrium, which are the source of abnormal electrical signals that can cause atrial fibrillation, by ablation. In catheter ablation using high-frequency current, the practitioner generates heat using high-frequency current between a therapeutic electrode catheter inserted into the heart, for example, through a large blood vessel in the patient's thigh, and a counter electrode plate attached to the patient's back, selectively ablating the myocardium to treat arrhythmias. Typically, the practitioner heats the tip of the electrode catheter to about 60°C and repeatedly ablates an area of ​​about 5 mm in diameter at a time of 60 seconds or less, so that the ablation marks are arranged in an arc around the pulmonary veins.

[0067] However, high-frequency currents may cause noise to other medical devices operating in the vicinity. Furthermore, high-frequency currents may ignite flammable materials such as high-concentration oxygen, alcohol, or gauze. Poor contact between the return electrode and the patient, or damage to the high-frequency cable, may cause burns to the practitioner or patient. The conductive gel applied to the return electrode may cause skin damage to the patient, such as allergic inflammation or skin damage when the return electrode is removed.

[0068] In contrast, the ablation catheter apparatus ACD using the ablation catheter CA including the heating element HE according to the embodiment of this disclosure does not use high-frequency current, and therefore does not require a counter electrode plate, conductive gel, high-frequency cable, or thermocouple for measuring the temperature of the heating element. As a result, the ablation catheter apparatus ACD according to the embodiment of this disclosure has the effect of suppressing or preventing the occurrence of noise, ignition of flammable materials, burns, or skin damage caused by the high-frequency current described above.

[0069] Furthermore, the ablation catheter apparatus ACD according to the embodiment of this disclosure can efficiently absorb the light emitted by the light source LS (irradiation light IL) by utilizing localized surface plasmon resonance, thereby enabling a thinner heating element HE.

[0070] Furthermore, the ablation catheter apparatus ACD according to the embodiment of this disclosure can narrow the wavelength range of the radiation light RL emitted by the heating element HE by utilizing localized surface plasmon resonance. In other words, it can suppress the emission of radiation light RL having wavelengths other than the resonance wavelength from the heating element HE, thereby suppressing the decrease in the temperature of the heating element HE due to the dissipation of radiant heat.

[0071] Thus, the ablation catheter device ACD according to the embodiment of this disclosure can efficiently heat the heating element HE while suppressing an undesirable decrease in the temperature of the heating element HE, thereby making it easier to maintain the temperature of the heating element HE at a desired temperature. Furthermore, because the ablation catheter device ACD according to the embodiment of this disclosure can suppress an undesirable decrease in the temperature of the heating element HE, it can improve energy-saving performance.

[0072] Furthermore, the heating element HE may have a laminated structure as shown in Figure 2, comprising a first conductor M1 that determines one of a plurality of resonance wavelengths, a second conductor M2 that determines another of the plurality of resonance wavelengths, a third conductor M3, and an insulator (dielectric DE) provided between each of the first conductor M1 and the second conductor M2 and the third conductor M3.

[0073] Specifically, the first conductor M1 may be configured to generate heat upon receiving irradiation light IL having a wavelength corresponding to one of a plurality of resonant wavelengths. Irradiation light IL is, for example, irradiation light emitted by a light source LS. The second conductor M2 may be configured to emit radiation light RL having a wavelength corresponding to another of a plurality of resonant wavelengths. Radiation light RL is, for example, radiation light emitted by a heat source HE. The third conductor M3 may be configured to be in direct contact with specific tissues in the patient's body. The layered structure may be, for example, a MIM (Metal-Insulator-Metal) structure.

[0074] This configuration is formed using known techniques such as physical deposition methods like sputtering, vacuum deposition, and pulsed laser deposition, or wet methods combining spin coating and sol-gel methods, resulting in the advantage of easy fabrication.

[0075] Furthermore, the first conductor M1 and the second conductor M2 may be electrically insulated, as shown in Figures 4, 8, 10, and 12. In this configuration, the heating element HE may have, for example, a nanodisk array structure in which multiple island-shaped conductors are dispersed in two dimensions. This configuration makes it possible to realize a heating element HE that is even easier to manufacture and further reduces the manufacturing cost of the heating element HE.

[0076] Furthermore, the first conductor M1 and the second conductor M2 may be integrated, as shown in Figure 11. In this configuration, the heating element HE may have, for example, a nanohole array structure in which multiple pores are dispersed in two dimensions within the conductive layer. This configuration allows, for example, the first conductor and the second conductor to be formed simultaneously using the same material and in the same process. Therefore, this configuration has the effect of realizing a heating element that is even easier to manufacture and further reducing the manufacturing cost of the heating element.

[0077] The insulator (dielectric DE) may include a first insulator (first dielectric DE1) provided between the first conductor M1 and the second conductor M2, and a second insulator (second dielectric DE2) provided between the second conductor M2 and the third conductor M3, as shown in Figure 12. In this configuration, the heating element HE may be configured such that, for example, the second conductor M2 is provided on the second insulator (second dielectric DE2) provided on the third conductor M3, and the first conductor M1 is provided on the first insulator (first dielectric DE1) provided on the second conductor M2. Therefore, this configuration has the effect of increasing the arrangement density of the first conductor M1 and the second conductor M2, that is, increasing the number per unit area, compared to the configuration shown in Figure 10 where the first conductor M1 and the second conductor M2 are arranged on the same single insulator (dielectric DE).

[0078] Preferred embodiments of the present disclosure have been described in detail above. However, the present invention is not limited to the embodiments described above. Various modifications or substitutions can be applied to the embodiments described above without departing from the scope of the present invention. Furthermore, each of the features described with reference to the embodiments described above may be combined as appropriate, as long as they do not conflict technically.

[0079] For example, in the above-described embodiment, the ablation catheter device ACD is described as a device used for the treatment of atrial fibrillation, but it may also be used for other treatments such as cancer treatment. Furthermore, the heating element HE may be used in other surgical energy devices other than the ablation catheter device ACD for performing thermal treatment.

[0080] Furthermore, in the embodiments described above, the metamaterial structure included in the heating element HE may have other structures such as a split-ring resonator (SRR) structure, a metal wire grid structure, a cut-wire structure, a fishnet structure, or a periodic multilayer structure. [Explanation of Symbols]

[0081] ACD... Ablation catheter device CA... Ablation catheter CTR... Control unit DE... Dielectric DE1... First dielectric DE2... Second dielectric HE, HE1, HE2, HEa, HEb, HEc... Heating element HT... Heat IL... Irradiation light LS... Light source LT1, LT3... Light M1... First conductor M2... Second conductor M3... Third conductor M12... Composite conductor OC... Optical circulator OF... Optical fiber OF1... First optical fiber OF2... Second optical fiber OF3... Third optical fiber PD... Photodetector RL... Radiation light

Claims

1. Optical fiber and A heating element fixed to one end of the optical fiber, A light source connected to the other end of the optical fiber, A light-receiving element that receives radiant light emitted by the aforementioned heat-generating element, An ablation catheter device having a control unit for controlling the temperature of the heating element, The heating element has multiple resonant wavelengths due to localized surface plasmon resonance, and is configured to generate heat when irradiated with light having a wavelength corresponding to one of the multiple resonant wavelengths, and to emit radiant light having a wavelength corresponding to another of the multiple resonant wavelengths at a predetermined intensity when it reaches a predetermined temperature. The light-receiving element detects the intensity of the radiated light emitted by the heating element through the optical fiber. The control unit controls the temperature of the heating element by adjusting the intensity of the irradiated light emitted by the light source based on data relating to the intensity of the radiated light output by the light receiving element. Ablation catheter device.

2. Optical fiber and A heating element fixed to one end of the optical fiber, A light source connected to the other end of the optical fiber, A light-receiving element that receives radiant light emitted by the aforementioned heat-generating element, An ablation catheter device having a control unit for controlling the temperature of the heating element, The light-receiving element detects the intensity of the radiated light emitted by the heating element through the optical fiber. The control unit controls the temperature of the heating element by adjusting the intensity of the irradiated light emitted by the light source based on data relating to the intensity of the radiated light output by the light receiving element. The heating element has multiple resonant wavelengths due to localized surface plasmon resonance, and is configured to generate heat when it receives irradiation light having a wavelength corresponding to one of the multiple resonant wavelengths, and to emit radiation light having a wavelength corresponding to another of the multiple resonant wavelengths. The aforementioned heating element is A plurality of first conductors that determine one of the plurality of resonance wavelengths, A plurality of second conductors that determine another one of the plurality of aforementioned resonant wavelengths, A third conductor and, It has a laminated structure comprising an insulator provided between each of the first conductor and the second conductor and the third conductor, The first conductor and the second conductor are electrically insulated from each other. On the insulator, each of the plurality of first conductors is arranged so as to be at equal intervals. On the insulator, each of the plurality of second conductors is arranged at equal intervals. Ablation catheter device.

3. The heating element is A first conductor that determines one of the multiple resonance wavelengths, A second conductor that determines another one of the multiple resonant wavelengths, A third conductor and, It has a laminated structure comprising an insulator provided between each of the first conductor and the second conductor and the third conductor, The first conductor and the second conductor are integrated. The ablation catheter device according to claim 1.

4. The insulator includes a first insulator provided between the first conductor and the second conductor, and a second insulator provided between the second conductor and the third conductor. The ablation catheter device according to claim 2.

5. Optical fiber and An ablation catheter having a heating element fixed to the tip of the optical fiber, The aforementioned heating element is It has multiple resonant wavelengths due to localized surface plasmon resonance, and is configured to generate heat when irradiated with light having a wavelength corresponding to one of the multiple resonant wavelengths, and to emit radiant light having a wavelength corresponding to another of the multiple resonant wavelengths. A plurality of first conductors that determine one of the plurality of resonance wavelengths, A plurality of second conductors that determine another one of the plurality of aforementioned resonant wavelengths, A third conductor and, The third conductor and an insulator provided between each of the first and second conductors, The first conductor and the second conductor are electrically insulated from each other. On the insulator, each of the plurality of first conductors is arranged so as to be at equal intervals. On the insulator, each of the plurality of second conductors is arranged at equal intervals. Ablation catheter.

6. A heating element having multiple resonant wavelengths due to localized surface plasmon resonance, A plurality of first conductors that determine one of the plurality of resonance wavelengths, A plurality of second conductors that determine another one of the plurality of aforementioned resonant wavelengths, A third conductor and, The third conductor and an insulator provided between each of the first and second conductors, The first conductor and the second conductor are electrically insulated from each other. On the insulator, each of the plurality of first conductors is arranged so as to be at equal intervals. On the insulator, each of the plurality of second conductors is arranged at equal intervals. Heating element.

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