Balloon catheter and method of manufacturing the same

Abstract

To provide: a balloon catheter capable of making it easy to contract a diameter of a balloon after diameter enlargement to a diameter of the balloon in the form of being folded before the diameter enlargement, thereby, making it possible to easily decrease the diameter of the balloon after the diameter enlargement more compact than conventional; and a manufacturing method of the balloon catheter.SOLUTION: There are provided a balloon catheter 1 and a manufacturing method of the balloon catheter. The balloon catheter includes: a shaft 10 which has a distal end 10a and a proximal end 10b and extends in a longitudinal direction x; a balloon 20 which is provided at a distal part of the shaft 10, can increase and decrease a diameter, and has folds 200; insulation base materials 30 arranged on an external surface of the balloon 20; and electrodes 40 arranged on the insulation base material 30. The insulation base material 30 has folding parts 32. The folding part 32 is lower in rigidity than parts 31 other than the folding part of the insulation base material 30, and the folding parts 32 are arranged on the folds 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a balloon catheter and a method for manufacturing a balloon catheter. [Background technology]

[0002] Pulmonary vein isolation for the treatment of atrial fibrillation uses an ablation catheter with a balloon having an ablation electrode on its outer surface. The balloon is expanded to bring the ablation electrode into contact with the pulmonary vein orifice, and high-frequency current is then applied to the ablation electrode to ablate the tissue at the pulmonary vein orifice.

[0003] Patent document 1 describes a medical device for tissue ablation, which includes a catheter shaft, an expandable balloon disposed on the catheter shaft and capable of changing between an unexpanded configuration and an expanded configuration, and a plurality of elongated electrode assemblies disposed on the outer surface of the balloon, each configured as a flexible circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2017-506096 Summary of the Invention [Problem to be solved by the invention]

[0005] The ablation balloon catheter is inserted into the lumen of a delivery sheath, delivered to the treatment site, and protruded from the sheath. A fluid is then injected into the balloon of the balloon catheter to expand the balloon. After the treatment is completed, the balloon is contracted and removed from the body cavity while still inserted into the lumen of the delivery sheath.

[0006] In the medical device described in Patent Document 1, when a balloon equipped with electrodes is expanded and then contracted, it is difficult to contract the diameter into a fixed shape, and therefore the outer diameter of the expanded balloon tends to be significantly larger than the outer diameter of the balloon before expansion, i.e., the outer diameter of an unused balloon. For this reason, the inner diameter of the delivery sheath must be set significantly larger than the outer diameter of the balloon before expansion so that the balloon can be inserted after expansion and contracted into an irregular shape, making it difficult to reduce the diameter of the sheath.

[0007] The present invention has been made in consideration of the above circumstances, and its object is to provide a balloon catheter and a method for manufacturing a balloon catheter that can easily contract the expanded balloon to the folded shape before expansion, thereby making it easier to contract the expanded balloon to a more compact shape than before. [Means for solving the problem]

[0008] One embodiment of the balloon catheter of the present invention, which has solved the above-mentioned problems, comprises a shaft extending in the longitudinal direction and having a distal end and a proximal end; a balloon provided at the distal portion of the shaft, capable of expanding and contracting in diameter, and having a fold; an insulating substrate disposed on the outer surface of the balloon; and an electrode disposed on the insulating substrate, the insulating substrate having a bent portion, the bent portion having a lower rigidity than the portion of the insulating substrate other than the bent portion, the bent portion being located on the fold. The balloon is folded along the fold and transported to the treatment site in a contracted state. After being expanded at the treatment site, the balloon must be contracted before being removed. The bent portion of the insulating substrate facilitates bending of the insulating substrate at the bent portion. Furthermore, the bent portion is located on the fold of the balloon, making it easier to fold the balloon along the fold. This facilitates contracting the expanded balloon to its pre-expansion shape, making it easier to contract the balloon to a compact size.

[0009] The electrodes do not have to be located on the folds.

[0010] The electrodes may be positioned on the folds.

[0011] There may be a plurality of folds, and the folds may be parallel to one another.

[0012] The folds may extend longitudinally along the shaft.

[0013] The electrodes may include an ablation electrode for ablatating biological tissue and a measurement electrode for measuring impedance, which are disposed on the insulating substrate.

[0014] The cauterizing electrode may be positioned closer to the bent portion than the measuring electrode.

[0015] Furthermore, a temperature sensor may be provided on the insulating substrate.

[0016] One embodiment of a method for manufacturing a balloon catheter of the present invention, which has solved the above-mentioned problems, includes the steps of: fixing an expandable and contractible balloon to a distal portion of a longitudinally extending shaft having a distal end and a proximal end; heating a mold for forming folds in the balloon and pressing the balloon with the mold to form folds in the balloon; forming a bent portion in an insulating substrate that is less rigid than other portions of the insulating substrate; arranging electrodes on the insulating substrate; and positioning the insulating substrate on the outer surface of the balloon so that the bent portion is located on the fold. The balloon is folded along the fold and transported to the treatment site in a contracted state. After expanding at the treatment site, the balloon must be contracted before being removed. The bent portion in the insulating substrate can easily prevent bending of the insulating substrate in areas other than the bent portion, making the insulating substrate more easily bent at the bent portion. Furthermore, the bent portion is located on the fold of the balloon, making it easier to fold the balloon along the fold. This allows the expanded balloon to be easily contracted to its pre-expansion shape, making it easier to contract the balloon to a compact size. Therefore, the above manufacturing method makes it possible to manufacture a balloon catheter that allows the balloon to be easily contracted to its pre-expansion shape, making it easier to contract the balloon to a compact size. [Effects of the Invention]

[0017] The balloon catheter of the present invention can be easily contracted to a compact size by easily contracting the expanded balloon to its pre-expansion shape. Furthermore, the method for manufacturing a balloon catheter of the present invention can be easily contracted to a compact size by easily contracting the expanded balloon to its pre-expansion shape. [Brief explanation of the drawings]

[0018] [Figure 1]1 is a side view (partial cross-sectional view) showing an example of a balloon catheter according to an embodiment of the present invention. [Figure 2] This shows an enlarged view of only the insulating substrate and electrodes shown in FIG. [Figure 3] FIG. 3 is a cross-sectional end view of the balloon catheter shown in FIG. 1 taken along line III-III. [Figure 4] 4 is a cross-sectional end view showing a state in which the balloon provided on the balloon catheter shown in FIG. 3 is folded. FIG. [Figure 5] 2 is a side view (partial cross-sectional view) showing a state in which a balloon provided on the balloon catheter shown in FIG. 1 is contracted in diameter. FIG. [Figure 6] FIG. 6 is a side view (partial cross-sectional view) showing the balloon catheter shown in FIG. 5 being inserted into a sheath. [Figure 7] 3A and 3B are diagrams showing modified examples of the insulating substrate and electrodes shown in FIG. 2. [Figure 8] 1 is a side view (partial cross-sectional view) showing an example of a mold used in a method for manufacturing a balloon catheter of the present invention. [Figure 9] 9 is a cross-sectional end view taken along line IX-IX in FIG. 8. [Figure 10] FIG. 10 shows a cross-sectional end view of the mold shown in FIG. 9 pressing a balloon. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the illustrated examples, and appropriate modifications may be made within the scope of the spirit described above and below, and all such modifications are within the technical scope of the present invention. In the drawings, hatching and symbols may be omitted for convenience. In such cases, reference should be made to the specification and other drawings. Furthermore, the dimensions of various parts in the drawings may differ from the actual dimensions, as priority is given to helping understand the features of the present invention.

[0020] One embodiment of the balloon catheter of the present invention comprises a shaft extending longitudinally and having a distal end and a proximal end; a balloon provided at the distal portion of the shaft, capable of expanding and contracting in diameter and having a fold; an insulating substrate disposed on the outer surface of the balloon; and an electrode disposed on the insulating substrate, the insulating substrate having a bent portion, the bent portion having a lower rigidity than the portion of the insulating substrate other than the bent portion, and the bent portion being disposed on the fold.

[0021] The overall configuration of a balloon catheter according to an embodiment of the present invention will be described with reference to Figures 1 to 7. Figures 1, 5, and 6 show a balloon catheter 1 having a shaft 10, a balloon 20, an insulating base material 30, and an electrode 40. In these figures, the longitudinal direction of the shaft 10 is indicated by x, and the radial direction is indicated by y. The radial direction y is a direction perpendicular to the longitudinal direction x, but only one direction perpendicular to the longitudinal direction x is shown here. The longitudinal direction x of the shaft 10 is the direction in which the shaft 10 extends.

[0022] In this specification, the proximal side refers to the side closest to the user in the extension direction of the shaft 10, and the distal side refers to the side opposite the proximal side, i.e., the side to be treated. Furthermore, the distal portion of each member refers to the distal half of each member, and the proximal portion of each member refers to the proximal half of each member.

[0023] FIG. 1 is a side view (partial cross-sectional view) showing an example of a balloon catheter according to an embodiment of the present invention, illustrating a state in which the balloon 20 is expanded. FIG. 2 is an enlarged view of only one insulating substrate 30 provided on the outer surface of the balloon 20 shown in FIG. 1 and an electrode 40 disposed on the insulating substrate 30. FIG. 3 is a cross-sectional end view of the balloon catheter 1 shown in FIG. 1 taken along line III-III. FIG. 4 is a cross-sectional end view showing the folded state of the balloon catheter 1 shown in FIG. 1, more specifically, a cross-sectional end view showing the balloon 20 provided on the balloon catheter shown in FIG. 3 folded along fold line 200. FIG. 5 is a side view showing the contracted state of the balloon 20 provided on the balloon catheter 1 shown in FIG. 1, more specifically, showing the state in which, after the balloon 20 is folded along fold line 200 as shown in FIG. 4, the radially outwardly protruding portion of the balloon 20 is folded circumferentially around the shaft 10 and wound around the shaft 10, thereby contracting the diameter. Fig. 5 shows a cross-sectional view of the delivery sheath 2 used when delivering the balloon catheter 1 to the treatment site. Fig. 6 shows a side view of the balloon catheter 1 shown in Fig. 5 inserted into the sheath 2, and shows a cross-sectional view of the sheath 2. Fig. 7 shows a modified example of the insulating substrate 30 and electrode 40 shown in Fig. 2.

[0024] 1, the balloon catheter 1 has a shaft 10. The shaft 10 has a distal end 10a and a proximal end 10b, and extends in a longitudinal direction x.

[0025] As shown in Fig. 1, the balloon catheter 1 has a balloon 20, which is provided at the distal portion of the shaft 10. As shown in Figs. 3 and 4, the balloon 20 is capable of expanding and contracting in diameter, and has a fold 200. The fold 200 is a line that is created when the balloon 20 is folded.

[0026] As shown in Figures 1 to 4, the balloon catheter 1 has an insulating base material 30. The insulating base material 30 is provided to hold the electrodes 40 (described later) on the balloon 20, and is a member that does not easily conduct electricity. The insulating base material 30 is disposed on the outer surface of the balloon 20, and has a bent portion 32. The bent portion 32 is a portion of the insulating base material 30 that is configured to have lower rigidity than the portion 31 other than the bent portion.

[0027] 1 to 4, the balloon catheter 1 has an electrode 40. The electrode 40 is used to create an electric field, pass a current, and extract an electric signal. The electrode 40 is disposed on an insulating substrate 30.

[0028] As shown in FIG. 1, in the balloon catheter 1, the folded portion 32 of the insulating base material 30 is disposed on the fold 200 of the balloon 20.

[0029] As shown in FIG. 6 , the balloon catheter 1 having the contracted balloon 20 is inserted into a delivery sheath 2 and delivered to the treatment site. As shown in FIG. 6 , the balloon 20 is folded along the fold 200 and delivered to the treatment site in a contracted state. As shown in FIG. 5 , the balloon 20 is then projected from the distal end of the sheath 2 and expanded at the treatment site as shown in FIG. 1 . The balloon 20 must then be contracted and reinserted into the sheath 2 before being removed. The provision of the folding portion 32 on the insulating substrate 30 can help prevent bending of the insulating substrate 30 at the portion 31 other than the folding portion, making the insulating substrate 30 more easily bent at the folding portion 32. Furthermore, because the folding portion 32 is located on the folding portion 200 of the balloon 20, the balloon 20, which has been expanded as shown in FIG. 3 , can be easily folded along the folding portion 200 as shown in FIG. 4 . This allows the expanded balloon 20 to be easily contracted to its original shape, making it more compact. Therefore, the inner diameter of the delivery sheath 2 used to deliver the balloon catheter 1 to the treatment site can be designed to be smaller than before, making it easier to make the sheath 2 thinner.

[0030] The balloon catheter 1 can be used, for example, as an ablation catheter used to cauterize biological tissue. One example of the use of the balloon catheter 1 is pulmonary vein isolation, which is one of the treatments for atrial fibrillation.

[0031] The shaft 10 is preferably flexible because it is inserted into the body, allowing it to be deformed to fit the shape of the body cavity. In addition, the shaft 10 is preferably elastic so that it can maintain its shape.

[0032] Examples of the shaft 10 include a hollow body formed by arranging one or more wires in a predetermined pattern; a hollow body having a resin coating on at least one of the inner and outer surfaces; a resin tube; or a combination of these, such as a combination of these connected in the longitudinal direction. Examples of hollow bodies having wires arranged in a predetermined pattern include a tubular body having a mesh structure formed by simply crossing or weaving wires, and a coil formed by winding wires. The wires may be one or more solid wires or one or more twisted wires. The resin tube can be manufactured, for example, by extrusion molding. When the shaft 10 is a resin tube, the shaft 10 can be composed of a single layer or multiple layers. A portion of the shaft 10 in the longitudinal direction x or circumferential direction may be composed of a single layer, and the other portion may be composed of multiple layers.

[0033] The shaft 10 can be made of, for example, synthetic resins such as polyolefin resins (e.g., polyethylene and polypropylene), polyamide resins (e.g., nylon), polyester resins (e.g., PET), aromatic polyether ketone resins (e.g., PEEK), polyether polyamide resins, polyurethane resins, polyimide resins, and fluororesins (e.g., PTFE, PFA, and ETFE), or metals such as stainless steel, carbon steel, and nickel-titanium alloys. These materials may be used alone or in combination of two or more.

[0034] 1, the shaft 10 may be composed of an outer tube 11 and an inner tube 12 disposed in the lumen of the outer tube 11. The lumen of the inner tube 12 can be used, for example, as a passage for inserting a guide wire.

[0035] As shown in Fig. 1, the proximal portion of the shaft 10 may be bifurcated. For example, a fluid regulator 52 (described later) may be connected to a first side of the bifurcation, and an operating unit 51 may be disposed on a second side of the bifurcation. As shown in Fig. 1, the operating unit 51 may be connected to the proximal portion of the inner tube 12.

[0036] The balloon 20 is preferably made of a resin. Examples of resins that make up the balloon 20 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, vinyl chloride resins, silicone resins, and natural rubber. These may be used alone or in combination of two or more. Of these, polyamide resins, polyester resins, and polyurethane resins are preferred. Elastomer resins can be used to make the balloon thinner and more flexible.

[0037] 1 , when the shaft 10 has an outer tube 11 and an inner tube 12, it is preferable that the inner tube 12 extends from the distal end of the outer tube 11 and penetrates the balloon 20 in the longitudinal direction x, the distal end of the balloon 20 is fixed to the distal portion of the inner tube 12, and the proximal end of the balloon 20 is fixed to the distal portion of the outer tube 12. The diameter of the balloon 20 can be expanded by injecting a fluid into the space between the outer tube 11 and the inner tube 12.

[0038] 1, a fluid regulator 52 such as a syringe may be connected to the proximal portion of the shaft 10 for supplying fluid to the interior of the balloon 20 or discharging fluid from the interior of the balloon 20. By supplying fluid to the interior of the balloon 20, the diameter of the balloon 20 can be expanded. By discharging fluid from the interior of the balloon 20, the diameter of the balloon 20 can be reduced.

[0039] Examples of the fluid supplied to the inside of the balloon 20 include liquids such as physiological saline, contrast medium, or a mixture thereof, and gases such as air, nitrogen, and carbon dioxide.

[0040] 1, balloon 20 has folds 200. Folds 200 can be formed in balloon 20 using a mold, for example, as described in detail in the section describing the method of manufacturing a balloon catheter.

[0041] As shown in FIG. 1, the balloon 20 may have a cylindrical straight tube portion 21, a distal tapered portion 22 provided distal to the straight tube portion 21, and a proximal tapered portion 23 provided proximal to the straight tube portion 21.

[0042] The folds 200 are preferably provided in the straight tube section 21 of the balloon 20. The folds 200 may be provided only in the straight tube section 21 of the balloon 20, or may be provided in all of the straight tube section 21, distal tapered section 22, and proximal tapered section 23 of the balloon 20.

[0043] As shown in FIGS. 1, 3, and 4, the balloon 20 may have multiple folds 200. The folds 200 may be arranged in parallel. While FIGS. 3 and 4 show an embodiment in which the balloon 20 has six folds 200, the number of folds 200 is not limited thereto and can be appropriately determined depending on the size of the balloon 20. For example, the number of folds 200 may be one or more, three or more, five or more, or seven or more. The number of folds 200 on the balloon 20 may be, for example, 15 or fewer, 10 or fewer, etc. The example shown in FIGS. 3 and 4 shows a balloon 20 having a first fold 201, a second fold 202, a third fold 203, a fourth fold 204, a fifth fold 205, and a sixth fold 206.

[0044] As shown in FIG. 4, the balloon 20 preferably has alternating mountain folds 200 and valley folds 200. Here, mountain folds 200 refer to folds 200 that protrude outward in the radial direction y, and valley folds 200 refer to folds 200 that protrude inward in the radial direction y. For example, in FIG. 4, the first fold 201, the third fold 203, and the fifth fold 205 are mountain folds 200, and the second fold 202, the fourth fold 204, and the sixth fold 206 are valley folds 200. By alternately providing the mountain folds 200 and the valley folds 200, the mountain folds 200 can be easily collapsed in the circumferential direction of the shaft 10 starting from the valley folds 200, making it easier to collapse the balloon 20 to a compact diameter.

[0045] 1, the folds 200 present in the balloon 20 may extend in the longitudinal direction x of the shaft 10. The folds 200 may extend entirely in the longitudinal direction x of the shaft 10, or only partially in the longitudinal direction x of the shaft 10.

[0046] The insulating substrate 30 is preferably flexible, which allows the insulating substrate 30 to easily follow the deformation of the balloon 20. Furthermore, the insulating substrate 30 may have elasticity in order to maintain its shape.

[0047] The insulating substrate 30 is preferably made of a resin, which can ensure the electrical insulation of the insulating substrate 30 and facilitate fixing to the balloon 20. Examples of resins that can be used to form the insulating substrate 30 include polyimide resin, polyamide resin, polyolefin resin, polyester resin, polycarbonate resin, and epoxy resin.

[0048] The insulating substrate 30 is disposed on the outer surface of the balloon 20. Specifically, the insulating substrate 30 is preferably fixed to the outer surface of the balloon 20, and more preferably to the outer surface of the straight tube portion 21 of the balloon 20. The insulating substrate 30 may be fixed to the outer surface of the balloon 20 by being directly or indirectly bonded thereto. The insulating substrate 30 can be fixed to the outer surface of the balloon 20 by, for example, welding or bonding with an adhesive.

[0049] The shape of the insulating substrate 30 is not particularly limited, but may be a circle, an oval, a polygon, or a combination thereof.

[0050] The insulating substrate 30 may be disposed on only a portion of the outer surface of the balloon 20. The insulating substrate 30 does not have to be disposed over the entire outer surface of the balloon 20. By providing the insulating substrate 30 on only a portion of the outer surface of the balloon 20, flexibility of the balloon 20 can be more easily ensured.

[0051] The insulating substrate 30 is preferably provided on the straight tube section 21 of the balloon 20. The insulating substrate 30 may be provided only on the straight tube section 21 of the balloon 20, or may be provided on all of the straight tube section 21, distal tapered section 22, and proximal tapered section 23 of the balloon 20.

[0052] The insulating base material 30 may be thicker in the portion other than the portion located on the fold 200 than in the portion located on the fold 200, or may be thinner in the portion other than the portion located on the fold 200 than in the portion located on the fold 200.

[0053] The bent portion 32 may be configured to have lower rigidity than the portion 31 of the insulating substrate 30 other than the bent portion. The bent portion 32 and the portion 31 other than the bent portion may be made of the same material or different materials. The thickness of the bent portion 32 may be smaller than the thickness of the portion 31 other than the bent portion, or the thickness of the bent portion 32 may be larger than the thickness of the portion 31 other than the bent portion.

[0054] For example, by configuring the bending portion 32 and the portion other than the bending portion 31 to be made of the same material and the thickness of the bending portion 32 to be smaller than the thickness of the portion other than the bending portion 31, the bending portion 32 can be configured to have lower rigidity than the portion other than the bending portion 31.

[0055] The material used for the portion 31 other than the bent portion can be configured to have a lower elongation rate than the material used for the bent portion 32, thereby making the bent portion 32 less rigid than the portion 31 other than the bent portion. For example, if the thickness of the bent portion 32 and the thickness of the portion 31 other than the bent portion are configured to be the same, the material used for the portion 31 other than the bent portion can be configured to have a lower elongation rate than the material used for the bent portion 32. The elongation rate here refers to the elongation rate (%) measured when a sample made of the material that makes up the bent portion 32 and a sample made of the material that makes up the portion 31 other than the bent portion, which has the same shape as the sample, are prepared, and one end and the other end of these samples are gripped with the same gripping width and pulled with the same strength (N).

[0056] 7, the bent portion 32 may be formed by making a broken line cut in the insulating base material 30. This allows the portion of the insulating base material 30 where the broken line cut is made to have lower rigidity than the other portions.

[0057] Although not shown, the bent portion 32 may be a bent mark formed by bending the insulating base material 30 formed in a plate or sheet shape. The portion where the bent mark is formed in this way has lower rigidity than the other portion.

[0058] As shown in Figures 1, 2, and 7, each insulating substrate 30 preferably has two non-folded portions 31, with a fold 32 located between the two non-folded portions 31. Furthermore, as shown in Figure 1, each insulating substrate 30 preferably has two non-folded portions 31, with a fold 32 located between the two non-folded portions 31, and is more preferably arranged symmetrically about a fold 200 of the balloon 20. This configuration facilitates folding of the non-folded portions 31 at the fold 32 from both sides of the fold 32, thereby facilitating folding of the balloon 20 at the fold 200 where the fold 32 is located. This facilitates shrinking the expanded balloon 20 to its original shape, making it easier to shrink it to a compact size.

[0059] 1, it is preferable that only the bent portion 32 of the insulating substrate 30 is positioned on the fold 200 of the balloon 20, and that the portion 31 other than the bent portion is not positioned on the fold 200 of the balloon 20. This makes it easier for the balloon 20 to be folded at the fold 200 of the balloon 20 where the bent portion 32 is positioned.

[0060] As shown in FIGS. 1 and 2, the bent portion 32 may have a smaller surface area than the portion 31 other than the bent portion.

[0061] As shown in FIG. 2, one insulating substrate 30 has two bent portions 32, and it is preferable that there is a gap 33 between the two bent portions 32 whose length in the longitudinal direction x of the shaft 10 is longer than that of the bent portions 32.

[0062] 1, one insulating substrate 30 has two bent portions 32, and between the two bent portions 32 there is a gap 33 that is longer in length in the longitudinal direction x of the shaft 10 than the bent portions 32, and more preferably the two bent portions 32 and the gap 33 are positioned on a fold 200 of the balloon 20. This makes it easier for the balloon 20 to be folded at the fold 200.

[0063] As shown in Figures 1, 2, and 7, the shape of the portion 31 other than the bent portions is preferably elongated. It is also preferable that the elongated portion 31 other than the bent portions extends in the longitudinal direction x of the shaft 10. It is more preferable that the elongated portion 31 other than the bent portions extends in the same direction as the folds 200. This makes it easier to fold the balloon 20 at the folds 200.

[0064] The material constituting the electrode 40 need only be conductive, and may be, for example, a metal or a mixture containing a resin and a metal. Among these, it is preferable to use a conductive resin or a metal such as gold, silver, copper, platinum, a platinum-iridium alloy, stainless steel, or tungsten.

[0065] The shape of the electrode 40 is not particularly limited, but may be a circle, an oval, a polygon, or a combination thereof.

[0066] The electrode 40 may be disposed at the bent portion 32, or may be disposed at the portion 31 other than the bent portion.

[0067] The electrode 40 can be disposed on the insulating substrate 30 by providing a thin film on the insulating substrate 30. The thin film can be formed by etching, vacuum deposition, sputtering, ion plating, plating, or coating.

[0068] Although not shown, the electrode 40 may be disposed on the fold 200 of the balloon 20. With this configuration, the insulating substrate 30 and the electrode 40 are disposed on the fold 200 of the balloon 20. When the fold 200 is formed using a heated mold as described below, the fold 200 portion is slightly more likely to stretch than the rest of the balloon 20, and when the balloon 20 is inflated, it is more likely to protrude slightly radially outward than the portions other than the fold 200. Therefore, by disposing the electrode 40 on the fold 200 of the balloon 20, it is possible to make the electrode 40 more easily contact the treatment site when the balloon 20 is expanded in diameter within the body cavity.

[0069] The electrode 40 may be thicker in the portion located on the fold 200 than in the portion other than the fold 200. If the fold 200 is formed using a heated mold as described below, the portion located on the fold 200 is slightly more stretchable than the other portions of the balloon 20, and is more likely to protrude slightly radially outward than the portion other than the fold 200 when the balloon 20 is inflated. By configuring the electrode 40 so that the portion other than the fold 200 is thicker than the portion located on the fold 200, it is possible to easily eliminate the difference in ease of contact with the treatment site between the portion located on the fold 200 and the other portion.

[0070] The electrode 40 may be thinner at the portion other than the portion located on the fold 200. This can make it easier to reduce the rigidity at the fold 200, making it easier to fold the balloon 20 at the fold 200.

[0071] 1, the electrodes 40 do not have to be positioned on the folds 200 of the balloon 20. This makes it easier to reduce the rigidity at the folds 200, making it easier to fold the balloon 20 at the folds 200.

[0072] The electrode 40 is preferably provided on the straight tube portion 21 of the balloon 20. The electrode 40 may be provided only on the straight tube portion 21 of the balloon 20, or may be provided on all of the straight tube portion 21, distal tapered portion 22, and proximal tapered portion 23 of the balloon 20.

[0073] As shown in FIGS. 1 to 4, the balloon catheter 1 may have electrodes 40 arranged on an insulating substrate 30, such as a cauterizing electrode 41 for cauterizing biological tissue and a measuring electrode 42 for measuring impedance.

[0074] The cauterizing electrode 41 is disposed on the insulating substrate 30 and is an electrode through which a high-frequency current is passed to cauterize biological tissue. More specifically, the cauterizing electrode 41 is fixed to the outer surface of the insulating substrate 30, and it is preferable that the cauterizing electrode 41 is exposed on the surface of the balloon 20 so that it can come into contact with biological tissue.

[0075] As shown in FIG. 1, when multiple cauterizing electrodes 41 are provided on one insulating substrate 30, it is preferable that the multiple cauterizing electrodes 41 are provided symmetrically with respect to the fold 200 of the balloon 20 as the axis.

[0076] 1 and 2, the shape of the cauterizing electrode 41 in a plan view may be a convex shape. Although not shown, the shape of the cauterizing electrode 41 in a plan view may be a rectangle or a polygon.

[0077] The ablation electrode 41 may be used not only to ablate biological tissue but also to measure the biopotential. The biopotential can be obtained, for example, by measuring the potential difference between the ablation electrode 41 and a reference electrode preferably provided on the balloon catheter 1. The reference electrode may be an electrode provided on the shaft 10 distal or proximal to the balloon 20, or a body surface electrode attached to the surface of the patient's body.

[0078] Although not shown, the cauterizing electrode 41 is connected to a first conductor, which preferably extends to the proximal side and is connected to a high-frequency generator 53. The cauterizing electrode 41 can be heated by applying a high-frequency electric field. The first conductor is preferably fixed to the insulating substrate 30. The high-frequency generator 53 may include a power supply circuit and a high-frequency oscillation circuit. Although not shown, an impedance matching circuit may be provided between the cauterizing electrode 41 and the high-frequency generator 53.

[0079] The measuring electrode 42 is an electrode provided for measuring the impedance of biological tissue. The surface area of ​​the measuring electrode 42 may be smaller than the surface area of ​​the ablation electrode 41. The measuring electrode 42 is preferably arranged around the ablation electrode 41 on the insulating substrate 30. It is preferable that a plurality of measuring electrodes 42 are provided on one insulating substrate 30.

[0080] As shown in FIG. 1, when multiple measurement electrodes 42 are provided on one insulating substrate 30, it is preferable that the multiple measurement electrodes 42 are provided symmetrically with respect to the fold 200 of the balloon 20 as the axis.

[0081] Although not shown, the measurement electrode 42 is connected to a second conductor, which preferably extends to the proximal side and is connected to the measurement unit 54. This allows a signal of the biopotential measured by the measurement electrode 42 to be sent to the measurement unit 54. The measurement unit 54 can measure the impedance between the measurement electrode 42 and the cauterizing electrode 41 and between the two measurement electrodes 30.

[0082] The first and second conductive wires may be conductive linear bodies such as conductive wires, or may be conductive materials printed on the insulating substrate 30. The first conductive wire may be disposed on the inner surface of the balloon 20, between the balloon 20 and the insulating substrate 30, or on the outer surface of the insulating substrate 30. The first and second conductive wires may be thin films of metal oxide or metal. The first conductive wire may be disposed on the outer surface, inner surface, thickened portion between the outer and inner surfaces of the shaft 10, or within the lumen.

[0083] As shown in FIGS. 1 and 2, the measurement electrode 42 may be disposed closer to the bent portion 32 than the cauterizing electrode 41.

[0084] As shown in FIG. 7, the cauterizing electrode 41 may be disposed closer to the bent portion 32 than the measuring electrode 42.

[0085] As shown in FIG. 1, the cauterizing electrode 41 may be positioned closer to the fold 200 than the measuring electrode 42 .

[0086] Although not shown, a temperature sensor may also be provided on the insulating substrate 30. The temperature sensor is a sensor that can measure the temperature around it. The temperature sensor may be provided in the bent portion 32, but from the viewpoint of making it easier to reduce the rigidity of the bent portion 32, it is preferable to provide the temperature sensor in the portion 31 other than the bent portion.

[0087] So far, the balloon catheter 1 according to the embodiment of the present invention has been described. Next, a method for manufacturing the balloon catheter according to the embodiment of the present invention will be described with reference to Figures 1 to 10. Components already described above will be assigned the same reference numerals and descriptions thereof will be omitted.

[0088] One embodiment of the method for manufacturing a balloon catheter of the present invention includes the steps of: fixing an expandable and contractible balloon to the distal portion of a shaft extending longitudinally and having a distal end and a proximal end; forming folds in the balloon by heating a mold for forming folds in the balloon and pressing the balloon with the mold; forming a bent portion in the insulating substrate that is less rigid than other portions of the insulating substrate; arranging electrodes on the insulating substrate; and arranging the insulating substrate on the outer surface of the balloon so that the bent portion is located on the fold.

[0089] Fig. 8 is a side view (partial cross-sectional view) showing an example of a mold used in the manufacturing method of the balloon catheter of the present invention. Fig. 9 is a cross-sectional end view taken along line IX-IX in Fig. 8. Fig. 10 is a cross-sectional end view showing the mold 60 shown in Fig. 9 pressing the balloon 24.

[0090] As shown in Figure 8, a balloon 24 capable of expanding and contracting in diameter is fixed to the distal portion of a shaft 10 having a distal end 10a and a proximal end and extending in the longitudinal direction x. The basic configuration of the balloon 24 fixed to the shaft 10 is the same as the balloon 20 described above, but differs in that the balloon 20 described above has folds 200, whereas the balloon 24 fixed to the distal portion of the shaft 10 does not have folds.

[0091] When forming folds in the balloon 24 fixed to the distal portion of the shaft 10, the mold 60 for forming the folds is heated.

[0092] As shown in Figures 8 and 9, the balloon 24 fixed to the distal portion of the shaft 10 is filled with fluid and set in a heated mold 60 in an expanded state. The balloon 24 is then pressed in the mold 60, forming folds in the balloon 24. When pressing the balloon 24 in the mold 60, it is preferable to press the balloon 24 in the mold 60 while contracting the balloon 24. In other words, it is preferable to press the balloon 24 in the mold 60 while discharging the fluid injected into the balloon 24. Figure 10 shows the balloon 20 in a state in which folds 200 have been formed by being pressed in the mold 60. The balloon 20 with folds 200 formed in this manner corresponds to the balloon 20 described above.

[0093] The insulating substrate 30 is formed with a bent portion 32 that has lower rigidity than the other portions of the insulating substrate 30. As described in the section explaining the balloon catheter, the bent portion 32 is configured to have lower rigidity than the portion 31 of the insulating substrate 30 other than the bent portion.

[0094] The electrode 40 is placed on the insulating substrate 30 with the bent portion 32 formed as described above. The electrode 40 is placed on the insulating substrate 30 as described in the section explaining the balloon catheter.

[0095] The insulating substrate 30 with the electrodes 40 arranged as described above is placed on the outer surface of the balloon 20 so that the folded portion 32 is positioned on the fold 200. As described in the section explaining the balloon catheter, the insulating substrate 30 is placed on the outer surface of the balloon 20.

[0096] The balloon 20 is folded along the folds 200 and transported to the treatment site in a reduced diameter state. After the balloon 20 is expanded at the treatment site, it must be reduced in diameter before being removed. The bends 32 on the insulating base material 30 facilitate preventing bending at the portions 31 of the insulating base material 30 other than the bends, making the insulating base material 30 more easily bent at the bends 32. Furthermore, the bends 32 are located on the folds 200 of the balloon 20, making it easier to fold the balloon 20 along the folds 200. This facilitates the expansion of the balloon 20, allowing it to be easily reduced in diameter to its pre-expansion shape and compact. Therefore, the above-described manufacturing method allows for the manufacture of a balloon catheter 1 that facilitates the expansion of the balloon 20 to its pre-expansion shape and compactness.

[0097] Before the step of fixing the expandable and contractible balloon 24 to the distal portion of the shaft 10, the method may include the step of preparing a shaft 10 having a distal end 10a and a proximal end and extending in the longitudinal direction x, the expandable and contractible balloon 24, an insulating substrate 30, an electrode 40, and a mold 60 for forming folds in the balloon 24.

[0098] The mold 60 may be any mold capable of forming folds in the balloon 24. For example, as shown in Fig. 9, the mold 60 may have a first portion 61 having an apex 61a formed to protrude toward the side where the shaft 10 is disposed, a second portion 62 disposed at a position different from the first portion 61 and having an apex 62a formed to protrude toward the side where the shaft 10 is disposed, and a third portion 63 disposed at a position different from the first portion 61 and the second portion 62 and having an apex 63a formed to protrude toward the side where the shaft 10 is disposed. The fold 200 can be formed by moving the first portion 61, the second portion 62, and the third portion 63 so that their respective apexes approach the shaft 10 and deflating the balloon 24. 8 to 10, a balloon 20 can be obtained that has a first fold 201, a second fold 202, a third fold 203, a fourth fold 204, a fifth fold 205, and a sixth fold 206. Also, by using the mold 60 shown in Figures 8 to 10, a balloon 20 that has alternating mountain folds 200 and valley folds 200 can be obtained, as shown in Figure 10.

[0099] As shown in Figures 9 and 10, the surface of the mold 60 that comes into contact with the balloon 24 is preferably curved. As a result, as shown in Figure 10, the radially protruding portions are inclined toward one circumferential direction of the shaft 10, making it easier for the radially protruding portions to collapse in one circumferential direction of the shaft 10. Therefore, after the balloon 20 is folded along the fold lines 200, the radially protruding portions are easier to collapse in the circumferential direction of the shaft 10, making it easier to wrap the balloon around the shaft 10. This makes it easier to reduce the diameter of the balloon 20.

[0100] The temperature that the portion of the mold 60 that comes into contact with the balloon 24 reaches when heated is not particularly limited as long as it is a temperature that allows the balloon 24 to be folded. [Explanation of symbols]

[0101] 1: Balloon catheter 2: Sheath 10: Shaft 11: Outer cylinder 12: Inner cylinder 20: Balloon 21: Straight pipe section 22: Distal tapered section 23: Proximal tapered section 200:Fold 201: First fold 202: Second fold 203: Third fold 204: Fourth fold 205: Fifth fold 206: Sixth fold 30: Insulating substrate 31: Parts other than the bent part 32: Bending part 40: Electrode 41: Cautery electrode 42: Measuring electrode 51:Operation unit 52: Fluid regulator 53: High frequency generator 54: Measuring part 60: Mold 61: Part 1 61a:Top 62:Second part 62a: top 63: 3rd part 63a: top

Claims

1. a longitudinally extending shaft having a distal end and a proximal end; a balloon provided at a distal portion of the shaft, capable of expanding and contracting in diameter, and having folds; an insulating substrate disposed on the outer surface of the balloon; an electrode disposed on the insulating substrate, the insulating substrate has a bent portion, and the bent portion has lower rigidity than a portion of the insulating substrate other than the bent portion; A balloon catheter in which the bent portion is disposed on the fold.

2. The balloon catheter according to claim 1 , wherein the electrodes are not disposed on the folds.

3. The balloon catheter according to claim 1 , wherein the electrodes are disposed on the folds.

4. The balloon catheter according to any one of claims 1 to 3, wherein there are a plurality of the folds, and the plurality of folds are arranged in parallel.

5. The balloon catheter according to any one of claims 1 to 4, wherein the folds extend in the longitudinal direction.

6. 6. The balloon catheter according to claim 1, wherein the electrodes are a cauterizing electrode for cauterizing biological tissue and a measuring electrode for measuring impedance, and the electrodes are disposed on the insulating substrate.

7. The balloon catheter according to claim 6, wherein the cauterizing electrode is disposed closer to the bent portion than the measuring electrode.

8. 8. The balloon catheter according to claim 1, further comprising a temperature sensor provided on the insulating substrate.

9. a balloon secured to a distal portion of a longitudinally extending shaft having a distal end and a proximal end, the balloon being expandable and contractible; forming folds in the balloon by heating a mold for forming folds in the balloon and pressing the balloon with the mold; forming a bent portion in an insulating substrate, the bent portion having a lower rigidity than other portions of the insulating substrate; disposing an electrode on the insulating substrate; and placing the insulating substrate on the outer surface of the balloon so that the bend is positioned on the crease.

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