Balloon catheter and operation method of balloon catheter

Abstract

To facilitate achievement of both shape followability and expansion controllability of a balloon in a balloon catheter.SOLUTION: A balloon catheter 1 includes: a shaft 2 including an expandable lumen 16 through which fluid passes; an inner layer balloon 20 located in a distal end side of the shaft 2, communicating with the expandable lumen 16 and being expandable when the fluid flows in the inner layer balloon 20; and an outer layer balloon 22 covering the inner layer balloon 20. A material forming the inner layer balloon 20 has a Young's modulus lower at the time of 20% extension than that of a material forming the outer layer balloon 22.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to balloon catheters and methods of operating balloon catheters. [Background technology]

[0002] Conventionally, a balloon catheter having a balloon provided on a catheter tube has been known (see, for example, Patent Document 1). Balloon catheters are used for various treatments such as removing foreign bodies such as stones, dilating strictures formed in the digestive tract, and stopping bleeding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-56806 Summary of the Invention [Problem to be solved by the invention]

[0004] A balloon is required to be able to follow the shape of the tube when expanding in the digestive tract or blood vessel, i.e., to have high shape-following ability. On the other hand, there may be a portion near the position where the balloon is expanded that should be avoided from contacting with the balloon. Alternatively, when expanding a balloon at a branched portion of the digestive tract or the like, it may be necessary to expand the balloon only to one side of the branch, and not to expand the balloon to the other side of the branch. For this reason, a balloon is required to be able to precisely control the expansion range, i.e., to have high expansion controllability.

[0005] One method for improving shape conformability is to form the balloon from a highly flexible material, but using a highly flexible material for the balloon can result in poor inflation controllability.

[0006] The present disclosure has been made in consideration of these circumstances, and its purpose is to provide a technology that makes it easier to achieve both the shape conformability and inflation controllability of a balloon in a balloon catheter. [Means for solving the problem]

[0007] One embodiment of the present disclosure is a balloon catheter. The balloon catheter includes a shaft having an expansion lumen through which a fluid passes, an inner layer balloon located at the distal end of the shaft and connected to the expansion lumen so as to be expandable by the inflow of a fluid, and an outer layer balloon covering the inner layer balloon. The material constituting the inner layer balloon has a lower Young's modulus at 20% stretch than the material constituting the outer layer balloon.

[0008] Another aspect of the present disclosure is a balloon catheter comprising: a shaft having an expansion lumen through which a fluid passes, an inner-layer balloon located at the distal end of the shaft and communicating with the expansion lumen to be inflatable by the inflow of a fluid, and an outer-layer balloon covering the inner-layer balloon, having a portion with a longer circumferential length than the uninflated inner-layer balloon in a cross-sectional view perpendicular to the axis of the shaft, and being expanded by being pressed by the expanding inner-layer balloon.

[0009] Another aspect of the present disclosure is a method of operating a balloon catheter, the method including injecting a fluid into an inner layer balloon to inflate the inner layer balloon, and causing the expanding inner layer balloon to press against an outer layer balloon covering the inner layer balloon, thereby expanding the balloon.

[0010] Any combination of the above components and any conversion of the expression of the present disclosure between a method, an apparatus, a system, etc. are also valid as aspects of the present disclosure. Effect of the Invention

[0011] According to the present disclosure, it is possible to easily achieve both shape conformability and expansion controllability of a balloon in a balloon catheter. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a side view of a balloon catheter according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a cross section along the axial direction of a balloon catheter. [Diagram 3] 3A is a cross-sectional view of a balloon catheter before the balloon is expanded, and FIG 3B is a cross-sectional view of a portion of the balloon before expansion. [Figure 4] 4A is a cross-sectional view of a balloon catheter in the middle of expanding the balloon, and FIG 4B is a cross-sectional view of a portion of the balloon in the middle of expanding the balloon. [Diagram 5] Figure 5(A) is a cross-sectional view of a balloon catheter with the balloon fully expanded, and Figure 5(B) is a cross-sectional view of a portion of the balloon fully expanded. [Figure 6] 1A to 1C are schematic diagrams illustrating a manner of use of a balloon catheter according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0014] Fig. 1 is a side view of a balloon catheter 1 according to an embodiment. Fig. 2 is a schematic diagram of a cross section along the axial direction of the balloon catheter 1. Fig. 1 shows a balloon 4 in a contracted state (state before expansion). Fig. 2 shows only a portion including the balloon 4. Also, in Fig. 2, the contrast marker 42 is not shown.

[0015] The balloon catheter 1 includes a shaft 2, a balloon 4, and a manifold 6. One end of the balloon catheter 1 is inserted into the body, and the other end is placed outside the body. Hereinafter, the side of the balloon catheter 1 that is inserted into the body will be referred to as the "distal side," and the side that is placed outside the body will be referred to as the "base side." In addition, for each member that constitutes the balloon catheter 1, the same side as the distal side of the balloon catheter 1 will be referred to as the "distal side" of that member, and the same side as the base side of the balloon catheter 1 will be referred to as the "base side" of that member.

[0016] The shaft 2 is a long tubular member. The length of the shaft 2 is, for example, 600 mm to 1800 mm. The shaft 2 has an outer shaft 8 and an inner shaft 10. Examples of materials for the outer shaft 8 and the inner shaft 10 include known flexible materials such as resins such as polyolefin and polyamide. The outer shaft 8 has a first lumen 12 through which the inner shaft 10 passes. The first lumen 12 is defined by the inner surface of a tube constituting the outer shaft 8, and the internal space of the tube becomes the first lumen 12. The first lumen 12 extends from the base end to the tip of the outer shaft 8. Therefore, an opening 28 of the second lumen 14 is formed at the tip of the shaft 2.

[0017] The inner shaft 10 has a second lumen 14 through which a guidewire GW (see FIG. 6) is passed. In other words, the second lumen 14 constitutes a guidewire lumen. The second lumen 14 is defined by the inner surface of a tube that constitutes the inner shaft 10, and the internal space of the tube constitutes the second lumen 14. The second lumen 14 extends from the base end to the tip end of the inner shaft 10. The outer diameter of the inner shaft 10 is smaller than the inner diameter of the outer shaft 8. Therefore, a space defined by the inner surface of the outer shaft 8 and the outer surface of the inner shaft 10 extends within the first lumen 12. This space constitutes an expansion lumen 16 through which a fluid F (see FIG. 4(A)) for expanding the balloon 4 passes.

[0018] The tip side of the inner shaft 10 protrudes from the outer shaft 8. A fixing ring 18 is fixed to the outer surface of the inner shaft 10 exposed from the first lumen 12. The fixing ring 18 is made of a known resin material, similar to the shaft 2. The inner shaft 10 and the fixing ring 18 are joined to each other, for example, by fusion.

[0019] The balloon 4 is located at the tip side of the shaft 2. The tip end of the balloon 4 is fixed to the portion of the inner shaft 10 that protrudes from the outer shaft 8, and the base end of the balloon 4 is fixed to the tip end of the outer shaft 8. The balloon 4 is delivered into the body by inserting the tip side of the shaft 2 into the patient's body.

[0020] The balloon 4 has an inner layer balloon 20 and an outer layer balloon 22. The inner layer balloon 20 and the outer layer balloon 22 are cylindrical bodies extending in the axial direction of the shaft 2. The tip of the inner layer balloon 20 is joined to the fixing ring 18 by fusion or the like. The fixing ring 18 may be omitted and the tip of the inner layer balloon 20 may be directly joined to the inner shaft 10. The base end of the inner layer balloon 20 is joined to the tip of the outer shaft 8 by fusion or the like. As a result, the tip of the expansion lumen 16 is connected to the inside of the inner layer balloon 20. The outer layer balloon 22 covers the inner layer balloon 20. For example, the inner surface of the tip of the outer layer balloon 22 and the outer surface of the tip of the inner layer balloon 20 are joined by fusion or the like. Also, the inner surface of the base end of the outer layer balloon 22 and the outer surface of the base end of the inner layer balloon 20 are joined by fusion or the like.

[0021] The material constituting the inner layer balloon 20 has a lower Young's modulus at 20% stretching than the material constituting the outer layer balloon 22. Thus, the inner layer balloon 20 has higher flexibility and lower rigidity than the outer layer balloon 22. In this embodiment, the Young's modulus of the material constituting each balloon at 20% stretching is calculated by a tensile test described below, and is the tensile modulus of a test piece cut out from each balloon when it is stretched by 20%, that is, when the test piece is 120% long. The Young's modulus of the material constituting the inner layer balloon 20 at 20% stretching is, for example, 0.1 MPa or more and 10 MPa or less, preferably 1 MPa or more and 5 MPa or less. The Young's modulus of the material constituting the outer layer balloon 22 at 20% stretching is, for example, 100 MPa or more and 1000 MPa or less, preferably 200 MPa or more and 500 MPa or less.

[0022] In the tensile test, a rectangular test piece with a width of 3 mm and a length of 15 mm was cut out from each balloon, and the test piece was clamped between chucks at 5 mm from both ends in the axial direction of the shaft 2. Therefore, the distance between the chucks was 5 mm. The gripping area of ​​the test piece in each chuck was 15 mm. 2Next, the test piece is pulled in the axial direction of the shaft 2 at room temperature of 23° C. and a pulling speed of 200 mm / min. Then, the Young's modulus at 20% elongation is calculated from the tensile stress and tensile strain when the test piece is elongated by 1 mm (20%).

[0023] As an example, the inner layer balloon 20 is a compliant balloon whose outer diameter changes when pressurized. The outer layer balloon 22 is a semi-compliant balloon whose outer diameter changes less when pressurized than a compliant balloon, or a non-compliant balloon whose outer diameter does not change substantially when pressurized. Examples of materials constituting the inner layer balloon 20 include latex, silicone rubber, urethane rubber, etc. Examples of materials constituting the outer layer balloon 22 include nylon, nylon elastomer, polyethylene terephthalate (PET), etc. The expansion mode of the balloon 4 will be described in detail later.

[0024] The manifold 6 is connected to the base end side of the shaft 2. With the tip side of the shaft 2 inserted into the patient's body, the manifold 6 is disposed outside the body and is held by the operator. The manifold 6 has a balloon expansion port 24 and a guidewire port 26. The second lumen 14, which constitutes the guidewire lumen, is connected to the guidewire port 26.

[0025] The expansion lumen 16 is connected to a balloon expansion port 24. The balloon 4 can be expanded by the inflow of a fluid F. Specifically, the fluid F is supplied to the balloon catheter 1 from a fluid supply / discharge device (not shown) connected to the balloon expansion port 24. Examples of the fluid F include liquids such as sterile distilled water and saline, and gases such as air. The fluid F flows through the balloon expansion port 24 and the expansion lumen 16 and flows into the inner-layer balloon 20. This causes the balloon 4 to expand. In addition, when the fluid supply / discharge device sucks in the fluid F, the fluid F in the inner-layer balloon 20 is discharged through the expansion lumen 16 and the balloon expansion port 24. This causes the balloon 4 to contract. Hereinafter, the expansion mode of the balloon 4 and the operation method of the balloon catheter 1 will be described in detail.

[0026] FIG. 3(A) is a cross-sectional view of the balloon catheter 1 before the balloon 4 is expanded. FIG. 3(B) is a cross-sectional view of a portion of the balloon 4 before expansion. FIG. 4(A) is a cross-sectional view of the balloon catheter 1 when the balloon 4 is in the middle of expansion. FIG. 4(B) is a cross-sectional view of a portion of the balloon 4 in the middle of expansion. FIG. 5(A) is a cross-sectional view of the balloon catheter 1 when the balloon 4 is fully expanded. FIG. 5(B) is a cross-sectional view of a portion of the balloon 4 when it is fully expanded. FIG. 3(A), FIG. 4(A) and FIG. 5(A) show cross sections perpendicular to the axis of the shaft 2 in the balloon catheter 1 (corresponding to the cross section along line AA in FIG. 1). FIG. 3(B), FIG. 4(B) and FIG. 5(B) show cross sections perpendicular to the axis of the shaft 2 in the balloon 4.

[0027] As shown in FIG. 3(A) and FIG. 3(B), in a cross-sectional view perpendicular to the axis of the shaft 2, the outer layer balloon 22 has a portion whose perimeter is longer than that of the unexpanded (before expansion, or before the inflow of the fluid F) inner layer balloon 20. This portion is preferably a portion excluding the joint between the inner layer balloon 20 and the outer layer balloon 22. The perimeter of this portion is, for example, 1.5 times or more the perimeter of the unexpanded inner layer balloon 20. In the balloon 4 before expansion, the outer layer balloon 22 is folded and wrapped around the inner layer balloon 20. The inner layer balloon 20 may or may not be folded. The folded outer layer balloon 22 has a plurality of pleats 22A. FIG. 3(A) shows a state in which five pleats 22A are formed, but the number of pleats 22A is not particularly limited. The plurality of pleats 22A are arranged at approximately equal intervals in the circumferential direction of the inner layer balloon 20. Each pleat 22A extends in the axial direction of the shaft 2 and is inclined in the circumferential direction of the shaft 2.

[0028] As shown in Figures 4(A) and 4(B), when fluid F is introduced into the inner layer balloon 20, the inner layer balloon 20 begins to elastically deform and expand as the internal pressure increases. As the inner layer balloon 20 expands, the outer surface of the inner layer balloon 20 comes into close contact with the inner surface of the outer layer balloon 22, and the outer layer balloon 22 is pressed by the inner layer balloon 20. This causes the outer layer balloon 22 to gradually expand. As the outer layer balloon 22 is pushed open, each pleat 22A gradually unfolds.

[0029] For convenience, Figures 4(A) and 4(B) show the balloon 4 expanding into a substantially perfect circle in cross section. However, before the outer layer balloon 22 is fully expanded, the outer layer balloon 22 deforms along the outer surface of the inner layer balloon 20. Therefore, the outer shape of the balloon 4 depends on the outer shape of the inner layer balloon 20. For this reason, the actual balloon 4 takes a shape that follows the shape of the tube wall or the like against which the balloon 4 is pressed.

[0030] As shown in Figures 5(A) and 5(B), the outer layer balloon 22 expands due to pressure from the inner layer balloon 20, and when each pleat 22A completely disappears, the expansion of the outer layer balloon 22 essentially stops. As described above, the outer layer balloon 22 has a higher Young's modulus at 20% stretch than the inner layer balloon 20, and is less deformed by pressure than the inner layer balloon 20. Therefore, when the outer layer balloon 22 is completely expanded, the expansion of the inner layer balloon 20 is significantly suppressed and essentially stops. When the outer layer balloon 22 is completely expanded, the outer shape of the balloon 4 depends on the outer shape of the outer layer balloon 22.

[0031] Next, a usage mode of the balloon catheter 1 will be described. Fig. 6 is a schematic diagram for explaining a usage mode of the balloon catheter 1 according to the embodiment. The balloon catheter 1 of the present embodiment can be used for various treatments such as stone removal, stricture dilation, hemostasis, and occlusion. As an example, the use of the balloon catheter 1 in bile duct stone removal will be described below.

[0032] An endoscope 30 equipped with a forceps channel 32 and a camera 34 is inserted into a duodenum 36 from a patient's mouth. A guidewire GW is inserted in advance into a common bile duct 38 through the forceps channel 32. A papilla 40 is present between the duodenum 36 and the common bile duct 38, but the guidewire GW, which has a diameter sufficiently smaller than the opening diameter of the papilla 40, can pass through the papilla 40 and enter the common bile duct 38. At this time, an operator of the endoscope 30 and the balloon catheter 1 can safely insert the guidewire GW into the papilla 40 while checking the image obtained from the camera 34.

[0033] With the guidewire GW inserted into the common bile duct 38, the base end of the guidewire GW is inserted into the second lumen 14 from the opening 28 at the tip of the shaft 2. The tip side of the shaft 2 is guided by the guidewire GW and passes through the forceps channel 32 to reach the duodenum 36. Next, the shaft 2 advances further from the state shown in FIG. 6 and is inserted into the common bile duct 38. As a result, the balloon 4 is placed in the common bile duct 38.

[0034] In this state, fluid F is supplied into the inner-layer balloon 20 via the balloon expansion port 24 and the expansion lumen 16, causing the inner-layer balloon 20 to expand and the outer-layer balloon 22 to expand. This causes the balloon 4 to assume a shape that conforms to the shape of the wall of the common bile duct 38. In this state, the balloon 4 is pulled out of the common bile duct 38. By this operation, stones accumulated in the common bile duct 38 can be scraped out into the duodenum 36.

[0035] 1, a contrast marker 42 is provided on the outer surface of the inner shaft 10 at a position overlapping with the balloon 4. A contrast agent is also mixed into the fluid F. The operator can check the position and expansion state of the balloon 4 in real time based on the contrast images taken during the procedure.

[0036] The balloon 4 of this embodiment has an inner layer balloon 20 with high flexibility. Before the outer layer balloon 22 is fully expanded, the outer shape of the balloon 4 depends on the outer shape of the inner layer balloon 20 with high flexibility. This allows the shape conformability of the balloon 4 to be improved. The balloon 4 also has an outer layer balloon 22 with low flexibility. Therefore, when the inner layer balloon 20 is expanded and the outer layer balloon 22 is fully expanded, further expansion of the inner layer balloon 20 is suppressed. This allows the balloon 4 to be suppressed from expanding in an unintended direction. In other words, the expansion controllability of the balloon 4 can be improved. Therefore, according to the balloon catheter 1 of this embodiment, it is possible to easily achieve both shape conformability and expansion controllability of the balloon 4.

[0037] Furthermore, if the balloon 4 is composed only of the inner-layer balloon 20, there is a possibility that the balloon 4 may be damaged due to contact with sharp stones, calcified lesions, or other medical instruments. In response to this problem, the balloon 4 of this embodiment has the highly rigid outer-layer balloon 22 as an outer shell. This reduces the possibility of the balloon 4 being damaged.

[0038] One method for reducing the risk of damage to the balloon 4 consisting only of the inner layer balloon 20 is to increase the thickness of the balloon 4. However, if the balloon 4 is made thicker, the balloon 4 before expansion will become thicker, which may make it difficult to insert the balloon 4 through the papilla 40 or other narrowed areas (reduced crossability). To address this issue, in this embodiment, the outer layer balloon 22, which has low flexibility, provides strength to the balloon 4. This makes it possible to reduce the risk of damage to the balloon 4 while suppressing an increase in the thickness of the balloon 4.

[0039] Furthermore, if the fluid F continues to flow in, the inner layer balloon 20 may expand excessively and burst. In response to this, by covering the inner layer balloon 20 with the outer layer balloon 22, an expansion limit can be set for the inner layer balloon 20. This makes it possible to prevent the balloon 4 from bursting. Furthermore, by setting an expansion limit for the inner layer balloon 20, the amount of fluid F that flows into the inner layer balloon 20 can be increased. This makes it possible to increase the internal pressure of the inner layer balloon 20. By increasing the internal pressure of the inner layer balloon 20, it becomes possible for the balloon 4 to tightly clamp the narrowed portion. This makes it possible to prevent the balloon 4 from shifting in the insertion / removal direction when the balloon 4 is expanded.

[0040] The balloon 4 may have a restraining member (not shown) in a portion in the axial direction of the shaft 2, which limits at least one of the inflation of the inner layer balloon 20 and the expansion of the outer layer balloon 22. The restraining member is formed, for example, of a circular elastic band. The restraining member causes a portion of the balloon 4 to expand less than other portions, or causes the expansion to be delayed. By expanding the balloon 4 with the portion of the balloon 4 where the restraining member is provided corresponding to the narrowed portion, the narrowed portion can be more reliably sandwiched by the balloon 4.

[0041] The above describes the embodiments of the present disclosure in detail. The above-mentioned embodiments merely show specific examples of implementing the present disclosure. The contents of the embodiments do not limit the technical scope of the present disclosure, and many design changes such as changes, additions, and deletions of components are possible within the scope of the idea of ​​the present disclosure defined in the claims. A new embodiment with a design change has the effects of each of the combined embodiments and modifications. In the above-mentioned embodiments, the contents for which such design changes are possible are emphasized by adding notations such as "in this embodiment" and "in this embodiment", but design changes are permitted even in contents without such notations. Any combination of components included in each embodiment is also valid as an aspect of the present disclosure. The hatching on the cross section of the drawing does not limit the material of the object to which the hatching is added.

[0042] The embodiment may be specified by the items described below. [1st item] a shaft (2) having an expansion lumen (16) through which a fluid (F) passes; an inner layer balloon (20) located at the distal end side of the shaft (2) and communicating with the expansion lumen (16) so as to be expandable by the inflow of a fluid (F); and an outer layer balloon (22) covering the inner layer balloon (20), The material constituting the inner layer balloon (20) has a lower Young's modulus at 20% stretch than the material constituting the outer layer balloon (22). Balloon catheter (1). [Second item] a shaft (2) having an expansion lumen (16) through which a fluid (F) passes; an inner layer balloon (20) located at the distal end side of the shaft (2) and communicating with the expansion lumen (16) so as to be inflatable by the inflow of a fluid (F); an outer layer balloon (22) which covers the inner layer balloon (20), has a portion whose circumferential length is longer than that of the uninflated inner layer balloon (20) in a cross-sectional view perpendicular to the axis of the shaft (2), and is expanded by being pressed by the expanding inner layer balloon (20); Balloon catheter (1). [3rd item] A fluid (F) is introduced into the inner layer balloon (20) to expand the inner layer balloon (20); The method includes expanding the outer layer balloon (22) covering the inner layer balloon (20) by pressing the inner layer balloon (20) with the expanding inner layer balloon (20). A method for operating a balloon catheter (1). [Explanation of symbols]

[0043] 1 balloon catheter, 2 shaft, 4 balloon, 16 expansion lumen, 20 inner layer balloon, 22 outer layer balloon, F fluid.

Claims

1. a shaft having an expandable lumen through which a fluid passes; an inner layer balloon located at the distal end side of the shaft, connected to the expansion lumen, and expandable by the inflow of the fluid; An outer layer balloon covering the inner layer balloon, the material constituting the inner layer balloon has a lower Young's modulus at 20% stretching than the material constituting the outer layer balloon; Balloon catheter.

2. a shaft having an expandable lumen through which a fluid passes; an inner layer balloon located at the distal end side of the shaft, connected to the expansion lumen, and inflatable by the inflow of the fluid; an outer layer balloon which covers the inner layer balloon, has a portion with a longer circumferential length than the uninflated inner layer balloon in a cross-sectional view perpendicular to the axis of the shaft, and is expanded by being pressed by the expanding inner layer balloon; Balloon catheter.

3. flowing a fluid into the inner layer balloon to inflate the inner layer balloon; and expanding the outer layer balloon covering the inner layer balloon by pressing the outer layer balloon with the expanding inner layer balloon. A method for operating a balloon catheter.

Images