JP7807280B2 - Balloon catheter and method of manufacturing the same - Google Patents

Description

The present invention relates to a balloon catheter and a method for manufacturing a balloon catheter.

In pulmonary vein isolation procedures for the treatment of atrial fibrillation, an ablation catheter is used that has a balloon with an ablation electrode attached to its outer surface. The balloon is expanded to bring the ablation electrode into contact with the pulmonary vein opening, and then high-frequency current is passed through the ablation electrode to ablate the tissue at the pulmonary vein opening.

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.

Special table 2017-506096 publication

The ablation balloon catheter is inserted into the lumen of a delivery sheath, delivered to the treatment site, where it protrudes from the sheath. Fluid is then injected into the balloon on the balloon catheter, expanding the balloon's diameter. After the treatment is complete, the balloon is contracted and removed from the body cavity while still inserted into the lumen of the delivery sheath.

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 it into a fixed shape. 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, in order to be able to insert a balloon that has been contracted into an irregular shape after expansion, the inner diameter of the delivery sheath must be set significantly larger than the outer diameter of the balloon before expansion, making it difficult to reduce the diameter of the sheath.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a balloon catheter and a method for manufacturing a balloon catheter that can easily collapse an expanded balloon into a more compact shape than conventional balloons by making it easier to collapse the expanded balloon into a more compact shape than conventional balloons.

One embodiment of the balloon catheter of the present invention, which has solved the above-mentioned problems, 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 has a bent portion, which is less rigid than the remaining portions of the insulating substrate, and the bent portion is disposed 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 on the insulating substrate facilitates the suppression of bending at portions of the insulating substrate other than the bent portion, making the insulating substrate more easily bent at the bent portion. Furthermore, the bent portion is disposed on the fold of the balloon, making it easier to fold the balloon along the fold. This facilitates the contraction of the expanded balloon to its pre-expansion shape, making it easier to contract the balloon to a compact size.

The electrodes do not have to be positioned on the folds.

The electrodes may be positioned on the folds.

There may be multiple folds, and the folds may be parallel.

The fold may extend longitudinally along the shaft.

The electrodes may include an ablation electrode for ablatating biological tissue and a measurement electrode for measuring impedance, which may be arranged on the insulating substrate.

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

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

One embodiment of the method for manufacturing a balloon catheter of the present invention, which solves the above-mentioned problems, comprises the steps of: fixing an expandable and contractible balloon to the 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 the insulating substrate that is less rigid than the remaining 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. 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 on 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, because the bent portion is located on the fold of the balloon, the balloon is easily folded along the fold. This makes it easier to shrink the expanded balloon back to its pre-expansion shape, making it easier to shrink it into a compact size. Therefore, the above manufacturing method makes it possible to manufacture a balloon catheter that can easily shrink the balloon back to its pre-expansion shape, making it easier to shrink it into a compact size.

The balloon catheter of the present invention can easily contract the expanded balloon to its pre-expansion shape, thereby making it easier to contract the diameter into a compact size. Furthermore, the method for manufacturing a balloon catheter of the present invention can easily contract the expanded balloon to its pre-expansion shape, thereby making it easier to manufacture a balloon catheter that can easily contract the diameter into a compact size.

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

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 above and below-described intent, all of which are within the technical scope of the present invention. Hatching and symbols may be omitted in the drawings for convenience; in such cases, reference should be made to the specification or other drawings. Furthermore, the dimensions of various parts in the drawings may differ from their actual dimensions, as priority is given to aiding understanding of the features of the present invention.

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 that is expandable and contractible and has 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 that is less rigid than the portion of the insulating substrate other than the bent portion, and the bent portion is disposed on the fold.

The overall structure 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 substrate 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 here only one direction perpendicular to the longitudinal direction x is shown. The longitudinal direction x of the shaft 10 is the direction in which the shaft 10 extends.

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 component refers to the distal half of that component, and the proximal portion of that component refers to the proximal half of that component.

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 the 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 the 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 state in which the balloon 20 provided on the balloon catheter shown in FIG. 3 is folded along the 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 the fold line 200 as shown in FIG. 4, the radially outward 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 also shows a cross-sectional view of the delivery sheath 2 used to deliver 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 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.

As shown in FIG. 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.

As shown in Figure 1, the balloon catheter 1 has a balloon 20, which is provided at the distal portion of the shaft 10. As shown in Figures 3 and 4, the balloon 20 can expand and contract in diameter and has a fold 200. The fold 200 is a line that is created when the balloon 20 is folded.

As shown in Figures 1 to 4, the balloon catheter 1 has an insulating substrate 30. The insulating substrate 30 is provided to hold the electrodes 40 (described below) to the balloon 20, and is a material that does not easily conduct electricity. The insulating substrate 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 substrate 30 that is configured to have lower rigidity than the portion 31 other than the bent portion.

As shown in Figures 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 electrical signal. The electrode 40 is disposed on an insulating substrate 30.

As shown in Figure 1, in the balloon catheter 1, the folded portion 32 of the insulating substrate 30 is positioned on the fold 200 of the balloon 20.

As shown in FIG. 6 , the balloon catheter 1 having a 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 extended 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 presence of the folding portion 32 on the insulating substrate 30 helps 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 was expanded as shown in FIG. 3 , is easily folded along the fold 200 as shown in FIG. 4 . This allows the expanded balloon 20 to be easily contracted to its pre-expansion shape, making it easier to contract to a compact size. This makes it easier to design the inner diameter of the delivery sheath 2, which is used to deliver the balloon catheter 1 to the treatment site, to be smaller than conventional designs, making it easier to reduce the diameter of the sheath 2.

The balloon catheter 1 can be used, for example, as an ablation catheter used to cauterize biological tissue. One example of an application of the balloon catheter 1 is pulmonary vein isolation, a treatment for atrial fibrillation.

Because the shaft 10 is inserted into the body, it is preferably flexible. This allows the shaft 10 to deform to fit the shape of the body cavity. It is also preferable that the shaft 10 be elastic so that it can maintain its shape.

Examples of the shaft 10 include a hollow body formed by arranging one or more wires in a predetermined pattern; a hollow body with 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 with wires arranged in a predetermined pattern include a tubular body with 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. A resin tube can be manufactured by extrusion molding, for example. 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.

The shaft 10 can be made of 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.

As shown in FIG. 1, the shaft 10 may be composed of an outer tube 11 and an inner tube 12 disposed within 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 guidewire.

As shown in FIG. 1, the proximal portion of the shaft 10 may be bifurcated. For example, a fluid regulator 52 (described below) may be connected to the first side of the bifurcation, and an operating unit 51 may be located on the 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.

The balloon 20 is preferably made of resin. Examples of resins that can be used to make 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.

As shown in FIG. 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, with the distal end of the balloon 20 fixed to the distal portion of the inner tube 12 and the proximal end of the balloon 20 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.

As shown in FIG. 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 and 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.

Examples of fluids supplied to the interior of the balloon 20 include liquids such as saline, contrast medium, or a mixture of these, and gases such as air, nitrogen, or carbon dioxide.

As shown in FIG. 1, the balloon 20 has folds 200. The folds 200 can be formed in the balloon 20 using a mold, for example, as described in detail in the section describing the method for manufacturing a balloon catheter.

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

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

As shown in Figures 1, 3, and 4, the balloon 20 may have multiple folds 200. There may be multiple folds 200, and the multiple folds 200 may be arranged in parallel. While Figures 3 and 4 show an embodiment in which the balloon 20 has six folds 200, the number of folds 200 is not limited to this and can be set appropriately depending on the size of the balloon 20, etc. 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 Figures 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.

As shown in FIG. 4, it is preferable that mountain folds 200 and valley folds 200 be alternately formed on the balloon 20. 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 forming mountain folds 200 and valley folds 200, the mountain folds 200 can be more 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.

As shown in FIG. 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.

The insulating substrate 30 is preferably flexible. This allows the insulating substrate 30 to easily follow the deformation of the balloon 20. Furthermore, the insulating substrate 30 may have elasticity to maintain its shape.

The insulating substrate 30 is preferably made of resin. This ensures the electrical insulation of the insulating substrate 30 and makes it easier to fix to the balloon 20. Examples of resins that can be used to make the insulating substrate 30 include polyimide resin, polyamide resin, polyolefin resin, polyester resin, polycarbonate resin, and epoxy resin.

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.

The shape of the insulating substrate 30 is not particularly limited, but can be circular, oval, polygonal, or a combination of these.

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, it becomes easier to ensure the flexibility of the balloon 20.

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.

The insulating substrate 30 may be thicker in the portion located on the fold 200 than in the portion other than the fold 200, or may be thinner in the portion other than the portion located on the fold 200.

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

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

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 two samples are prepared: one made of the material that makes up the bent portion 32, and the other made of the material that makes up the portion 31 other than the bent portion, which is formed to the same shape as the sample; and the samples are gripped at one end and the other end with the same gripping width and pulled with the same strength (N).

Alternatively, as shown in Figure 7, the bent portion 32 may be formed by cutting a broken line into the insulating substrate 30. This allows the portion of the insulating substrate 30 where the broken line cut is made to be configured to have lower rigidity than the other portions.

Although not shown, the bent portion 32 may be a crease formed by bending the insulating substrate 30 formed in a plate or sheet shape. The portion where the crease is formed in this way will have lower rigidity than the other portions.

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

As shown in FIG. 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 fold at the fold 200 of the balloon 20 where the bent portion 32 is positioned when the balloon 20 is folded.

As shown in Figures 1 and 2, the folded portion 32 may have a smaller surface area than the portion 31 other than the folded portion.

As shown in Figure 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.

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

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

The material that makes up the electrode 40 needs only to be conductive, and can be made of, for example, a metal or a mixture containing a resin and a metal. Among these, it is preferable to use conductive resin or metals such as gold, silver, copper, platinum, platinum-iridium alloy, stainless steel, and tungsten.

The shape of the electrode 40 is not particularly limited, but can be circular, oval, polygonal, or a combination thereof.

The electrode 40 may be located in the bent portion 32, or in a portion 31 other than the bent portion.

One method for disposing the electrode 40 on the insulating substrate 30 is to provide a thin film on the insulating substrate 30. The thin film can be formed by etching, vacuum deposition, sputtering, ion plating, plating, or coating.

Although not shown, the electrode 40 may be positioned on the fold 200 of the balloon 20. With this configuration, the insulating substrate 30 and electrode 40 are positioned 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 expanded, it is more likely to protrude slightly radially outward than the portions other than the fold 200. Therefore, by positioning 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.

The electrode 40 may be thicker in the areas other than the folds 200. If the folds 200 are formed using a heated mold as described below, the folds 200 are slightly more stretchable than the rest of the balloon 20, and are more likely to protrude slightly radially outward than the areas other than the folds 200 when the balloon 20 is inflated. By configuring the electrode 40 so that the areas other than the folds 200 are thicker than the areas on the folds 200, it is possible to eliminate any difference in the ease of contact with the treatment area between the areas on the folds 200 and the areas other than the folds 200.

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

As shown in FIG. 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.

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.

As shown in Figures 1 to 4, the balloon catheter 1 may include electrodes 40, such as an ablation electrode 41 that ablates biological tissue and a measurement electrode 42 that measures impedance, arranged on an insulating substrate 30.

The cauterizing electrode 41 is disposed on the insulating substrate 30 and is an electrode through which 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 be exposed on the surface of the balloon 20 so that it can come into contact with biological tissue.

As shown in Figure 1, when multiple cauterization electrodes 41 are provided on one insulating substrate 30, it is preferable that the multiple cauterization electrodes 41 be provided in line symmetry with respect to the fold 200 of the balloon 20 as the axis.

As shown in Figures 1 and 2, the shape of the cauterizing electrode 41 in a planar view may be convex. Although not shown, the shape of the cauterizing electrode 41 in a planar view may also be rectangular or polygonal.

The ablation electrode 41 may be used not only to ablate biological tissue but also to measure bioelectric potential. The bioelectric potential can be obtained, for example, by measuring the potential difference between the ablation electrode 41 and a reference electrode, which is 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.

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.

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

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

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 cauterization electrode 41, and between the two measurement electrodes 30.

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, or thickened portion between the outer and inner surfaces of the shaft 10, or within the lumen.

As shown in Figures 1 and 2, the measurement electrode 42 may be positioned closer to the bent portion 32 than the cauterizing electrode 41.

As shown in Figure 7, the cauterizing electrode 41 may be positioned closer to the bent portion 32 than the measuring electrode 42.

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

Although not shown, a temperature sensor may also be provided on the insulating substrate 30. The temperature sensor is capable of measuring the temperature around it. The temperature sensor may be provided in the bent portion 32, but from the perspective of making it easier to reduce the rigidity of the bent portion 32, it is preferable to provide it in a portion 31 other than the bent portion.

So far, we have described the balloon catheter 1 according to an embodiment of the present invention. Next, we will explain a method for manufacturing a balloon catheter according to an embodiment of the present invention with reference to Figures 1 to 10. Components already described above will be assigned the same reference numerals and will not be described again.

One embodiment of the method for manufacturing a balloon catheter of the present invention comprises the steps of: fixing an expandable and contractible balloon to the distal portion of a longitudinally extending shaft 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 folded 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 folded portion is positioned on the fold.

Figure 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. Figure 9 is a cross-sectional end view taken along line IX-IX in Figure 8. Figure 10 is a cross-sectional end view showing the mold 60 shown in Figure 9 pressing the balloon 24.

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 similar to that of the balloon 20 described above, except that the balloon 20 described above has a fold 200, whereas the balloon 24 fixed to the distal portion of the shaft 10 does not have a fold.

To form folds in the balloon 24 fixed to the distal portion of the shaft 10, the mold 60 for forming the folds is heated.

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 it. 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.

The insulating substrate 30 is formed with a bent portion 32 that has lower rigidity than the rest of the insulating substrate 30. As described in the section describing the balloon catheter, the bent portion 32 is configured to have lower rigidity than the rest of the insulating substrate 30 (31) other than the bent portion.

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

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.

The balloon 20 is folded along the folds 200 and transported to the treatment site in a reduced diameter state. After expanding the balloon 20 at the treatment site, the balloon 20 must be reduced in diameter before being removed. The presence of the folds 32 on the insulating base material 30 helps prevent bending at the portions 31 other than the folds, making it easier to fold the insulating base material 30 at the folds 32. Furthermore, because the folds 32 are located on the folds 200 of the balloon 20, the balloon 20 is easily folded along the folds 200. This makes it easier to reduce the diameter of the expanded balloon 20 back to its pre-expansion shape, making it easier to reduce the diameter to a compact size. Therefore, the above manufacturing method makes it possible to manufacture a balloon catheter 1 that can easily reduce the diameter of the balloon 20 back to its pre-expansion shape, making it easier to reduce the diameter to a compact size.

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.

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 placed, a second portion 62 positioned at a different position from the first portion 61 and having an apex 62a formed to protrude toward the side where the shaft 10 is placed, and a third portion 63 positioned at a different position 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 placed. The folds 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. When using the mold 60 shown in Figures 8 to 10, 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 can be obtained. Furthermore, by using the mold 60 shown in Figures 8 to 10, a balloon 20 having alternating mountain folds 200 and valley folds 200 can be obtained, as shown in Figure 10.

As shown in Figures 9 and 10, it is preferable that the surface of the mold 60 that comes into contact with the balloon 24 is 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 folds 200, the radially protruding portions are easier to collapse in the circumferential direction of the shaft 10, making it easier to wrap around the shaft 10. This makes it easier to reduce the diameter of the balloon 20.

The temperature that is reached by heating the portion of the mold 60 that comes into contact with the balloon 24 is not particularly limited, as long as it is a temperature that can create creases in the balloon 24.

1: Balloon catheter 2: Sheath 10: Shaft 11: Outer tube 12: Inner tube 20: Balloon 21: Straight tube 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 base material 31: Portion other than folded section 32: Folded section 40: Electrode 41: Cautery electrode 42: Measurement electrode 51: Operation section 52: Fluid regulator 53: High frequency generator 54: Measurement section 60: Mold 61: First section 61a: Top section 62: Second section 62a: Top section 63: Third section 63a: Top section

Claims (9)

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. The balloon catheter of claim 1, wherein the electrodes are not positioned on the folds. The balloon catheter of claim 1, wherein the electrodes are positioned on the folds. A balloon catheter according to any one of claims 1 to 3, wherein there are multiple folds, and the multiple folds are arranged in parallel. A balloon catheter according to any one of claims 1 to 4, wherein the folds extend in the longitudinal direction. A balloon catheter according to any one of claims 1 to 5, wherein the electrodes, an ablation electrode for ablatating biological tissue and a measurement electrode for measuring impedance, are disposed on the insulating substrate. The balloon catheter according to claim 6, wherein the ablation electrode is positioned closer to the bent portion than the measurement electrode. The balloon catheter according to any one of claims 1 to 7, further comprising a temperature sensor provided on the insulating substrate. 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 fold.