Balloon catheter balloon and balloon catheter provided therewith

Abstract

Provided is a balloon catheter balloon that easily follows an inner wall of a constricted section and that is capable of enhancing the constricted-section expanding performance by easily coming into contact with the inner wall of the constricted section.　A balloon (20) having a balloon membrane (20M) that contains a first layer (20a) and a second layer (20b) having a greater shore D hardness than the first layer (20a), wherein the second layer (20b) is positioned farther outside than the first layer (20a), the rate of change (|Tx-Ta| / Ta)×100) of the membrane thickness Tx with respect to the average membrane thickness Ta of the balloon membrane (20M) is equal to or less than 15%, the average membrane thickness T1a of the first layer (20a) is equal to or greater than 2 μm, and the rate of change (|T1x-T1a| / T1a)×100) of the membrane thickness T1x with respect to the average membrane thickness T1a of the first layer (20a) is equal to or greater than 20%.

Description

Balloon for balloon catheter and balloon catheter equipped with same

[0001] The present invention relates to a balloon for a balloon catheter and a balloon catheter including the same.

[0002] The formation of stenoses in the inner walls of blood vessels can lead to diseases such as angina pectoris and myocardial infarction. One of the treatments for these conditions is angioplasty, such as percutaneous transluminal coronary angioplasty (PTCA) or percutaneous transluminal angioplasty (PTA), which uses a balloon catheter to dilate the stenosis. Angioplasty is a minimally invasive treatment that does not require open chest surgery like bypass surgery, and is widely used.

[0003] In angioplasty, the distal end of a balloon provided at the distal portion of a balloon catheter is inserted through a puncture site in the femoral artery, brachial artery, etc., and the balloon is delivered to the lesion site through the vascular lumen by manipulating the balloon catheter from the proximal side. For this reason, balloon catheters with balloons that have improved insertion properties or balloons with protrusions that can dilate stenotic sites have been developed. For example, Patent Document 1 discloses a balloon catheter in which the entire balloon is made of the same material, thereby reducing the diameter and improving insertion properties, and Patent Document 2 discloses a balloon catheter in which expansion functions are provided to protrusions that are more rigid than the balloon wall.

[0004] Patent Document 1: JP 2014-155657 A, US Patent Application Publication No. 2016 / 0128718

[0005] However, with the above-mentioned conventional balloon catheters, when the balloon is delivered to the lesion and then expanded in a region with a complex lumen shape, such as a stenosis, the balloon is unable to make sufficient contact with the inner wall of the lesion, making it impossible to efficiently expand the stenosis.

[0006] In view of the above circumstances, an object of the present invention is to provide a balloon for a balloon catheter that, when inflating the balloon at a narrowed portion, easily conforms to the inner wall of the narrowed portion and easily comes into contact with the inner wall of the narrowed portion, thereby improving the expansion performance of the narrowed portion, and a balloon catheter equipped with the same.

[0007] The following are embodiments of a balloon catheter balloon according to the present invention that have solved the above-mentioned problems: [1] A balloon catheter balloon having a balloon membrane having longitudinal, radial, and circumferential directions, the balloon membrane including a first layer and a second layer made of a material having a Shore D hardness higher than that of the first layer, the first and second layers being disposed over 360° in the circumferential direction, the second layer being positioned radially outward of the first layer, the rate of change (|Tx - Ta| / Ta) × 100) of the thickness Tx of the balloon membrane at an arbitrary position x in the circumferential direction relative to the average thickness Ta of the balloon membrane in a cross section perpendicular to the longitudinal direction being 15% or less, the average thickness T1a of the first layer being 2 μm or greater, and the rate of change (|T1x - T1a| / T1a) × 100) of the thickness T1x of the first layer at an arbitrary position x in the circumferential direction relative to the average thickness T1a of the first layer in a cross section perpendicular to the longitudinal direction being 20% ​​or greater. [2] The balloon catheter balloon according to [1], wherein, in a cross section perpendicular to the longitudinal axis, when quadrants obtained by dividing 360° of the circumferential direction by 120° are designated as first, second, and third quadrants, in each quadrant, the rate of change (|T1x - T1a| / T1a) × 100) of the thickness T1x of the first layer at any given position x in the circumferential direction relative to the average thickness T1a of the first layer is 20% or more. [3] The balloon catheter balloon according to [2], wherein, in each of the first, second, and third quadrants, the thickness T1x of the first layer is greater than 50% of the thickness Tx of the balloon membrane at the given position x, and the thickness T2x of the second layer at any given position x in the circumferential direction is greater than 50% of the thickness Tx of the balloon membrane at the given position x.[4] The balloon for a balloon catheter according to [3], wherein a plurality of the first layer rich regions and a plurality of the second layer rich regions are arranged in the circumferential direction of each of the quadrants, the total range over which the first layer rich regions are arranged is 30° or more out of 120° in the circumferential direction of each of the quadrants, the total range over which the second layer rich regions are arranged is 30° or more out of 120° in the circumferential direction of each of the quadrants, and the first layer rich regions and the second layer rich regions are arranged alternately in the circumferential direction. [5] The balloon for a balloon catheter according to any one of [1] to [4], wherein the balloon has a first-layer rich portion in which the thickness T1x of the first layer is greater than 50% of the thickness Tx of the balloon membrane at any position x in the circumferential direction, and a second-layer rich portion in which the thickness T2x of the second layer at any position x in the circumferential direction is greater than 50% of the thickness Tx of the balloon membrane at that position x, wherein a plurality of the first-layer rich portions and a plurality of the second-layer rich portions are arranged in the circumferential direction, each of the first-layer rich portions and each of the second-layer rich portions is arranged over an area of ​​15° or more out of 360° in the circumferential direction of the balloon membrane, and the first-layer rich portions and the second-layer rich portions are arranged alternately.

[0008] The present invention also provides the following: [6] A balloon catheter comprising the balloon for a balloon catheter according to any one of [1] to [5] above.

[0009] The above-mentioned balloon for a balloon catheter and a balloon catheter equipped with the same can provide a balloon catheter that, when inflated at a narrowed area, easily conforms to the inner wall of the narrowed area and easily comes into contact with the inner wall of the narrowed area, thereby improving the expansion performance of the narrowed area, and a balloon catheter equipped with the same.

[0010] 1 shows a side view of a balloon catheter according to one embodiment of the present invention. 2 shows a cross-sectional view taken along line II-II of the balloon catheter shown in FIG. 1. 3 shows an enlarged view of the first quadrant of the cross-sectional view shown in FIG. 2. 4 shows a cross-sectional view illustrating a modification of the cross-sectional view II-II. 5 shows a perspective view of a parison before biaxial stretching according to one embodiment of the present invention. 6 shows a cross-sectional view taken along line VI-VI of the parison shown in FIG. 5. 7 shows a cross-sectional view perpendicular to the longitudinal axis direction of a parison mold used to manufacture the parison shown in FIG. 6. 8 shows a cross-sectional view taken along the longitudinal axis direction of a mold according to one embodiment of the present invention. 9 shows a cross-sectional view taken along line IX-IX of FIG. 8.

[0011] The present invention will be described below based on the embodiments, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience. In such cases, please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping understand the features of the present invention.

[0012] 1. Balloon for Balloon Catheter A balloon for balloon catheter according to an embodiment of the present invention is a balloon for balloon catheter having a balloon membrane having longitudinal, radial, and circumferential directions, the balloon membrane including a first layer and a second layer made of a material having a higher Shore D hardness than the first layer, the first and second layers being arranged over a full 360° circumferential range, the second layer being positioned radially outward of the first layer, and in a cross section perpendicular to the longitudinal direction, the rate of change (|Tx - Ta| / Ta) x 100) of the thickness Tx of the balloon membrane at an arbitrary position x in the circumferential direction relative to the average thickness Ta of the balloon membrane is 15% or less, the average thickness T1a of the first layer is 2 μm or greater, and in a cross section perpendicular to the longitudinal direction, the rate of change (|T1x - T1a| / T1a) x 100) of the thickness T1x of the first layer at an arbitrary position x in the circumferential direction relative to the average thickness T1a of the first layer is 20% or greater.

[0013] To dilate a stenotic site using a balloon catheter, the balloon attached to the distal end of the balloon catheter must be inserted into the lumen of a blood vessel, delivered to the stenotic site, and then inflated to bring the outer wall of the balloon into contact with and press against the inner wall of the stenotic site. If there is a portion of the balloon's outer wall that does not fit the inner wall of the stenotic site, the efficiency of dilating that portion may decrease even after the balloon is inflated. However, in the balloon catheter balloon described above, the rate of change (|Tx - Ta| / Ta) × 100) of the balloon membrane's thickness Tx at any circumferential position x relative to the balloon membrane's average thickness Ta is 15% or less, the balloon membrane includes a first layer and a second layer having a higher Shore D hardness than the first layer, both of which are disposed over the entire 360° circumferential direction, and the rate of change (|T1x - T1a| / T1a) × 100) of the first layer's thickness T1x at any circumferential position x relative to the first layer's average thickness T1a is 20% or more, thereby allowing the balloon membrane to have varying stiffness in the circumferential direction. This allows the highly flexible portion of the balloon membrane in the circumferential direction, i.e., the thick portion of the first layer with a lower Shore D hardness, to more easily conform to the irregularities in the stricture, allowing the outer wall of the balloon to easily contact the inner wall of the stricture, improving the dilation performance of the stricture. In addition, the balloon membrane has a thick second layer with a high Shore D hardness in some areas, ensuring the rigidity of the balloon and improving its pressure resistance. Furthermore, the second layer is located radially outward of the first layer, which contributes to improving the expansion performance of the stenotic area.

[0014] In this specification, a balloon for a balloon catheter may be simply referred to as a "balloon."

[0015] A balloon for a balloon catheter according to an embodiment of the present invention will be described below with reference to Figures 1 to 4. Figure 1 is a side view of a balloon catheter according to an embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II of the balloon catheter shown in Figure 1. In Figure 2, the boundaries of each quadrant are indicated by dotted lines, and the boundary between the first-layer rich portion and the second-layer rich portion is indicated by a dashed-dotted line. Figure 3 is an enlarged view of the first quadrant of the cross-sectional view shown in Figure 2. The inner shaft is omitted in Figure 3, and the boundaries of each quadrant are indicated by dotted lines, and the boundary between the first-layer rich portion and the second-layer rich portion is indicated by a dashed-dotted line. Figure 4 is a cross-sectional view showing a modification of the cross-sectional view taken along line II-II of Figure 2, and the boundary between the first-layer rich portion and the second-layer rich portion is indicated by a dashed-dotted line.

[0016] As shown in FIG. 1 , the balloon 20 is provided at the distal portion of the balloon catheter 10. The balloon 20 is connected to the distal end of the shaft 30, and the balloon 20 can be expanded by introducing fluid through the lumen of the shaft 30, and can be deflated by discharging the fluid. To control the expansion and deflation of the balloon 20, an indeflator (balloon pressurizer) can be used to introduce or discharge fluid. The fluid may be pressurized fluid pressurized by a pump or the like. The balloon catheter 10 will be described in detail in the section "2. Balloon Catheter."

[0017] 2 , the balloon 20 has a longitudinal axis direction x1, a radial direction y1 connecting the centroid 20C of the outer edge of the balloon 20 to a point on the outer edge in a cross section perpendicular to the longitudinal axis direction x1, and a circumferential direction z1 along the outer edge of the balloon 20 in a cross section perpendicular to the longitudinal axis direction x1. In this specification, the direction toward the user's hand in the longitudinal axis direction x1 is referred to as the proximal side, and the side opposite the proximal side, i.e., the direction toward the treatment subject, is referred to as the distal side.

[0018] The components and parts other than the balloon 20 each have a longitudinal axis direction, a radial direction, and a circumferential direction, which may or may not be the same as the longitudinal axis direction x1, radial direction y1, and circumferential direction z1 of the balloon 20. However, for ease of understanding, this specification will be described as assuming that all components and parts have the same longitudinal axis direction, radial direction, and circumferential direction as the longitudinal axis direction x1, radial direction y1, and circumferential direction z1 of the balloon 20.

[0019] As shown in FIG. 2 , the balloon 20 has a balloon membrane 20M including a first layer 20a and a second layer 20b made of a material with a higher Shore D hardness than the first layer 20a. The first layer 20a and the second layer 20b are disposed over 360° in the circumferential direction z1, and the second layer 20b is positioned radially outward of the first layer 20a in the radial direction y1. The first layer 20a, which has a low Shore D hardness, is disposed continuously over 360° in the circumferential direction z1, thereby improving the flexibility of the balloon 20. The second layer 20b, which has a high Shore D hardness, is disposed continuously over 360° in the circumferential direction z1, thereby ensuring the rigidity of the balloon 20. Furthermore, the second layer 20b, which has a high Shore D hardness, is positioned radially outward in the radial direction y1, thereby contributing to improved inflation efficiency when the outer wall of the balloon 20 comes into contact with a stricture.

[0020] In a cross section perpendicular to the longitudinal axis direction x1, the rate of change of the thickness Tx of the balloon membrane 20M at an arbitrary position x in the circumferential direction z1 relative to the average thickness Ta of the balloon membrane 20M, i.e., the absolute value of the value obtained by subtracting Ta from Tx, divided by Ta, multiplied by 100, (|Tx - Ta| / Ta) x 100(%), is 15% or less, and the average thickness T1a of the first layer 20a is 2 μm or more. In a cross section perpendicular to the longitudinal axis direction x1, the rate of change of the thickness T1x of the first layer 20a at an arbitrary position x in the circumferential direction z1 relative to the average thickness T1a of the first layer 20a, i.e., the absolute value of the value obtained by subtracting T1a from T1x, divided by T1a, multiplied by 100, (|T1x - T1a| / T1a) x 100(%), is 20% or more. The rate of change in the thickness of the balloon membrane 20M is 15% or less, while the rate of change in the thickness T1x of the first layer 20a, whose average thickness T1a is 2 μm or greater, is 20% or greater. This allows the balloon membrane 20M to have different rigidity depending on the position in the circumferential direction z1. This allows the highly flexible portion of the balloon membrane 20M in the circumferential direction z1, i.e., the thick portion of the first layer 20a, which has a low Shore D hardness, to easily conform to the more irregular parts of the stenosis, allowing the outer wall of the balloon 20 to easily contact the inner wall of the stenosis, improving the dilation performance of the stenosis. A method for more efficiently achieving this effect includes, for example, rotating the balloon 20 axially after the balloon 20 reaches the stenosis at a pressure lower than the balloon pressure used for treatment. Furthermore, because the balloon membrane 20M also has a thick portion of the second layer 20b, which has a high Shore D hardness, the rigidity of the balloon 20 is ensured, improving its pressure resistance.

[0021] The rate of change in the thickness Tx of the balloon membrane 20M at any position x in the circumferential direction z1 relative to the average thickness Ta of the balloon membrane 20M is 15% or less, preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less. By setting the upper limit of the rate of change in thickness Tx of the balloon membrane 20M in the circumferential direction z1 within the above range, the outer surface of the balloon 20 does not protrude outward in the radial direction y1, making it easier to conform the outer wall of the balloon 20 to the lumen shape of the stenosis. Furthermore, the balloon membrane 20M can be made to have a uniform thickness, which is advantageous in terms of the flexibility and durability of the balloon 20. Ideally, the lower limit of the rate of change in thickness Tx of the balloon membrane 20M in the circumferential direction z1 is 0%, but in practice it can be set to 1% or more, 2% or more, 3% or more, etc.

[0022] The Shore D hardness of the first layer 20a is preferably 20 or more, 25 or more, 30 or more, 35 or more, or 40 or more, and is preferably 70 or less, 65 or less, 60 or less, or 55 or less. The Shore D hardness of the second layer 20b is preferably more than 70, 72 or more, 74 or more, or 75 or more, and is preferably 90 or less, 85 or less, or 80 or less. When the Shore D hardnesses of the first layer 20a and the second layer 20b are within the above ranges, the above-mentioned effects can be achieved.

[0023] The Shore D hardness can be measured using a type D durometer, for example, in accordance with the description of JIS K6253-2: 2012. The Shore D hardness of each of the first layer 20a and the second layer 20b may be the Shore D hardness of the material before it is molded into the balloon 20.

[0024] Suitable materials for the second layer 20b include polyamide resins such as nylon 11 and nylon 12, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polyurethane resins. Suitable materials for the first layer 20a include thermoplastic elastomers, which have low Shore D hardness. For example, suitable materials for the first layer 20a include polyamide elastomers such as polyether block amide copolymers.

[0025] As shown in FIGS. 2 to 4 , the balloon 20 may be composed of only the balloon membrane 20M. Alternatively, although not shown, the balloon 20 may have layers other than the balloon membrane 20M. When the balloon 20 has layers other than the balloon membrane 20M, the balloon 20 may have a configuration in which the balloon membrane 20M has the above-described configuration and a second balloon membrane or a third balloon membrane is disposed on the inner or outer side of the balloon membrane 20M in the radial direction y1. Even in such a configuration, as long as the balloon membrane 20M has the above-described configuration, a balloon having multiple balloon membranes is included in the balloon 20 according to the present invention.

[0026] The average thickness Ta of the balloon membrane 20M is preferably 12 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less.

[0027] The average thickness T1a of the first layer 20a is 2 μm or more, and can be set to a range less than the average thickness Ta of the balloon membrane 20M, for example, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, or 55 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less.

[0028] The balloon membrane 20M may be composed of only the first layer 20a and the second layer 20b, in which case the thickness of the second layer 20b is the thickness of the balloon membrane 20M minus the thickness of the first layer 20a. The average thickness of the second layer 20b is preferably 2 μm or more, and can be, for example, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, or 55 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less, as long as it is within the range less than the average thickness Ta of the balloon membrane 20M.

[0029] In a cross section perpendicular to the longitudinal axis direction x1, the rate of change of the thickness T1x of the first layer 20a at any position x in the circumferential direction z1 relative to the average thickness T1a of the first layer 20a is 20% or more, preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, and preferably 95% or less, more preferably 90% or less, and even more preferably 80% or less. Since the balloon membrane 20M has a uniform thickness of a predetermined value or less, when the thickness T1x of the first layer 20a has a rate of change within the above range, the thickness T2x of the second layer 20b also has a rate of change of approximately the above range. As shown in FIG. 2, the balloon membrane 20M can have a portion rich in the first layer 20a, which has a low Shore D hardness, and a portion rich in the second layer 20b, which has a high Shore D hardness, depending on the position in the circumferential direction z1.

[0030] Each membrane thickness can be measured by observing a cross section perpendicular to the longitudinal axis direction x1 of the balloon 20. For example, an optical microscope can be used for observation, and the membrane thickness can be obtained from the membrane thickness measurement value and observation magnification of the obtained observation image. The average membrane thickness Ta of the balloon membrane 20M can be obtained by measuring the membrane thickness at 24 points equally spaced 15° apart within 360° of the circumferential direction z1 of the balloon membrane 20M and calculating the average value of the 24 points. The 24 points 15° apart can be determined as points on 24 line segments by drawing line segments in the radial direction y1 from the centroid 20C of the outer edge of the balloon 20 to the outer edge of the balloon 20 so that the central angle (the smaller one) θ between the centroid 20C of the outer edge of the balloon 20 and the line segments connecting the centroid 20C of the outer edge of the balloon 20 is 15°. The number of measurement points to obtain the average membrane thickness Ta is not limited to 24 and may be smaller or larger, but at least eight or more points are preferred.

[0031] The membrane thickness is preferably measured by observing the balloon 20 in an expanded state. The method for maintaining the balloon 20 in an expanded state is not particularly limited, but examples include a method of burying the balloon 20 in an expanded state in a curable resin for observation, exposing a cross section perpendicular to the longitudinal axis direction x1, and observing the cross section. Alternatively, the balloon 20 may be observed directly without being buried in a curable resin, or the balloon 20 in a contracted state may be observed as long as the central angle θ can be determined.

[0032] The thickness Tx of the balloon membrane 20M at any position x in the circumferential direction z1 is not limited to the point measured when determining the average thickness Ta, but can be obtained by observing the thickness at any position x in the circumferential direction z1 in the same manner as described above.

[0033] The average thickness T1a of the first layer 20a and the thickness T1x of the first layer 20a at an arbitrary position x in the circumferential direction z1 can also be measured in the same manner as for the balloon membrane 20M. Because the first layer 20a and the second layer 20b are formed from different resins, the boundary between the layers can be observed by microscopic observation, and the thickness of each layer can be determined.

[0034] The rate of change of the thickness T1x of the first layer 20a at an arbitrary position x in the circumferential direction z1 with respect to the average thickness T1a is calculated by first obtaining the average thickness T1a of the first layer 20a as described above, and then calculating the thickness T1x of the first layer 20a at the position X1 as shown in FIG. １ is measured and calculated using the formula (|T1x １ -T1a| / T1a)×100. As shown in FIG. 3, the thickness of the first layer 20a at position X1 is thicker than the thickness at other positions, and the thickness of the first layer 20a at position X1 varies to the side thicker than the average thickness T1a of the first layer 20a. Similarly, at position X2, the thickness T1x of the first layer 20a at position X2 ２ is measured and calculated using the formula (|T1x ２ The rate of variation at position X2 is calculated from (-T1a| / T1a) × 100. At position X2, the thickness of the first layer 20a is thinner than at other positions, and the thickness of the first layer 20a at position X2 is thinner than the average thickness T1a of the first layer 20a. Thus, the thickness of the first layer 20a preferably varies by at least 20% thicker and at least 20% thinner than the average thickness T1a. This makes it easier to change the rigidity of the balloon membrane 20M depending on the position in the circumferential direction z1.

[0035] As shown in FIG. 2 , in a cross section perpendicular to the longitudinal axis x1, 360° of the circumferential direction z1 is divided into quadrants, designated as the first quadrant R1, the second quadrant R2, and the third quadrant R3, with the central angle θ of 120° each. In each quadrant, the rate of change (|T1x-T1a| / T1a)×100 of the thickness T1x of the first layer 20a at any position x in the circumferential direction z1 relative to the average thickness T1a of the first layer 20a is preferably 20% or greater. Having the rate of change (|T1x-T1a| / T1a) of the thickness T1x of the first layer 20a in each quadrant equal to or greater than a predetermined value facilitates varying the stiffness of the balloon membrane 20M throughout the circumferential direction z1, ensuring that thick portions of the highly flexible first layer 20a are evenly distributed along the circumferential direction z1 of the balloon membrane 20M. This allows the outer wall of the balloon 20 to more easily conform to the inner wall of the stricture, making it easier for the outer wall of the balloon 20 to come into contact with the inner wall of the stricture, thereby improving the dilation performance of the stricture.

[0036] As shown in Figures 2 and 3, in each of the first quadrant R1, the second quadrant R2, and the third quadrant R3, there is preferably a first-layer rich portion 20A in which the thickness T1x of the first layer 20a is more than 50% of the thickness Tx of the balloon membrane 20M at a position x, and a second-layer rich portion 20B in which the thickness T2x of the second layer 20b at an arbitrary position x in the circumferential direction z1 is more than 50% of the thickness Tx of the balloon membrane 20M at the position x. The thickness T1x of the first layer 20a and the thickness Tx of the balloon membrane 20M are preferably compared at the same position x. The thickness T2x of the second layer 20b and the thickness Tx of the balloon membrane 20M are preferably compared at the same position x. For example, as shown in Figure 3, the thickness T1x of the first layer 20a and the thickness Tx of the balloon membrane 20M are compared at a position X1, and the thickness T1x of the first layer 20a at the position X1 is １ is the thickness Tx of the balloon membrane 20M at the position X1 １ 3, the thickness T2x of the second layer 20b and the thickness Tx of the balloon membrane 20M are compared at the position X2, and the thickness T2x of the second layer 20b at the position X2 is determined to be the first layer rich portion 20A. ２ is the thickness Tx of the balloon membrane 20M at the position X2 ２, the position X2 can be determined to be the second layer rich portion 20B.

[0037] Because each quadrant has a first-layer rich portion 20A and a second-layer rich portion 20B, the rigidity of the balloon membrane 20M can be varied more significantly throughout the entire circumferential direction z1 of the balloon 20. Because the flexibility of the balloon membrane 20M is increased in the first-layer rich portion 20A, the first-layer rich portion 20A is more likely to deform to conform to the lumen shape of the stenosis, making it easier to bring the outer wall of the balloon 20 into contact with the inner wall of the stenosis. Furthermore, because each quadrant has the first-layer rich portion 20A, the flexible portion of the balloon membrane 20M is not biased toward a portion of the circumferential direction z1. This reduces the need to axially rotate the balloon 20 to align the outer wall of the balloon 20 with the inner wall of the stenosis, enabling a safer procedure. The second-layer rich portion 20B has higher rigidity, which contributes to improving the strength and pressure resistance of the balloon 20.

[0038] As shown in FIG. 3 , a plurality of first-layer rich portions 20A and a plurality of second-layer rich portions 20B are arranged in the circumferential direction z1 of each quadrant. The total area over which the first-layer rich portions 20A are arranged is 30° or more out of 120° in the circumferential direction z1 of each quadrant, and the total area over which the second-layer rich portions 20B are arranged is 30° or more out of 120° in the circumferential direction z1 of each quadrant. The first-layer rich portions 20A and the second-layer rich portions 20B are preferably arranged alternately in the circumferential direction z1. The total area over which the second-layer rich portions 20B are arranged in the circumferential direction z1 of each quadrant is preferably greater than the total area over which the first-layer rich portions 20A are arranged. With this configuration, the second-layer rich portions 20B ensure the rigidity of the balloon 20, while the portion over which the first-layer rich portions 20A are arranged can function as a flexible buffer. This allows the balloon 20 to more easily conform to the inner wall of the stenosis, thereby more easily improving the dilatation function of the stenosis. Alternatively, the total area in the circumferential direction z1 of each quadrant where the second-layer rich portion 20B is disposed may be smaller than the total area where the first-layer rich portion 20A is disposed, which further improves the flexibility of the balloon 20 and makes it easier for the balloon 20 to conform to the inner wall of the stenosis.

[0039] The range in which the first layer rich portion 20A and the second layer rich portion 20B are arranged can be defined as the smaller angle formed by two line segments connecting the centroid 20C of the outer edge of the balloon 20 to the positions of both ends of each portion in a cross section perpendicular to the longitudinal axis direction x1. Since multiple first layer rich portions 20A and multiple second layer rich portions 20B are arranged in each quadrant, the total range in which the first layer rich portions 20A are arranged is the sum of the angles θa1, θa2, and θa3, and the total range in which the second layer rich portions 20B are arranged is the sum of the angles θb1 and θb2.

[0040] By ensuring that the total angle of the first-layer rich portion 20A and the second-layer rich portion 20B in each quadrant is 30° or greater, the highly flexible first-layer rich portion 20A and the highly rigid second-layer rich portion 20B can be arranged over a range greater than or equal to a predetermined value in each quadrant, making it easier to vary the flexibility and rigidity of the balloon 20 over the entire circumferential direction z1.

[0041] As shown in FIG. 4 , the balloon 20 has a first-layer rich portion 20A in which the thickness T1x of the first layer 20a at any position x in the circumferential direction z1 is more than 50% of the thickness Tx of the balloon membrane 20M at the position x, and a second-layer rich portion 20B in which the thickness T2x of the second layer 20b at any position x in the circumferential direction z1 is more than 50% of the thickness Tx of the balloon membrane 20M at the position x. In the circumferential direction z1, a plurality of the first-layer rich portions 20A and a plurality of the second-layer rich portions 20B are arranged. The range θa over which each first-layer rich portion 20A is arranged and the range θb over which each second-layer rich portion 20B is arranged are preferably 15° or more out of 360° in the circumferential direction z1 of the balloon membrane 20M. The first-layer rich portions 20A and the second-layer rich portions 20B are preferably arranged alternately.

[0042] In the circumferential direction z1 of the balloon 20, the first-layer rich portion 20A and the second-layer rich portion 20B are each arranged over a range equal to or greater than a predetermined range, and the first-layer rich portion 20A and the second-layer rich portion 20B are arranged alternately, so that portions that are softer than the predetermined range and portions that are harder than the predetermined range alternate in the circumferential direction z1. This makes it easier to make the outer wall of the balloon 20 conform to the inner wall of the stenosis.

[0043] The range θa within which each first-layer rich portion 20A is disposed is preferably 20° or more, even more preferably 30° or more, and preferably 60° or less, and more preferably 45° or less. The range θb within which each second-layer rich portion 20B is disposed is preferably 20° or more, even more preferably 30° or more, and preferably 60° or less, and more preferably 45° or less. The number of first-layer rich portions 20A depends on the range θa within which each first-layer rich portion 20A is disposed, but is preferably 12 or less, more preferably 9 or less, particularly preferably 6 or less, and preferably 3 or more, and more preferably 4 or more. The number of second-layer rich portions 20B depends on the range θb within which each second-layer rich portion 20B is disposed, but is preferably 12 or less, more preferably 9 or less, particularly preferably 6 or less, and preferably 3 or more, and more preferably 4 or more.

[0044] The range θa over which each first-layer rich portion 20A is disposed may be larger than the range θb over which each second-layer rich portion 20B is disposed. By increasing the range θa over which each first-layer rich portion 20A is disposed, it is possible to ensure that the balloon 20 has many flexible portions in the circumferential direction z1. Alternatively, the range θb over which each second-layer rich portion 20B is disposed may be larger than the range θa over which each first-layer rich portion 20A is disposed. By increasing the range θb over which each second-layer rich portion 20B is disposed, it is possible to ensure that the balloon 20 has many rigid portions in the circumferential direction z1.

[0045] As shown in Fig. 1, the balloon 20 has a proximal end and a distal end in the longitudinal axis direction x1, and preferably includes a straight tube section 23, a proximal tapered section 22 located proximal to the straight tube section 23, a proximal sleeve section 21 located proximal to the proximal tapered section 22, a distal tapered section 24 located distal to the straight tube section 23, and a distal sleeve section 25 located distal to the distal tapered section 24. The straight tube section 23 is preferably substantially cylindrical and has approximately the same diameter in the longitudinal axis direction x1, but may have different diameters in the longitudinal axis direction x1. The proximal tapered section 22 and the distal tapered section 24 are preferably formed into a substantially conical or truncated conical shape with a diameter decreasing with increasing distance from the straight tube section 23. Because the straight tube portion 23 has the largest diameter, when the balloon 20 is inflated at the narrowed portion, the straight tube portion 23 comes into sufficient contact with the inner wall of the narrowed portion, facilitating treatment such as dilating the narrowed portion. Furthermore, because the proximal tapered portion 22 and the distal tapered portion 24 have reduced diameters, when the balloon 20 is deflated, the outer diameters of the proximal and distal ends of the balloon 20 can be reduced to reduce the step between the shaft 30 and the balloon 20, making it easier to insert the balloon 20 into a body cavity.

[0046] While the proximal tapered section 22, the straight tube section 23, and the distal tapered section 24 are sections that expand when a fluid is introduced into the balloon 20, it is preferable that the proximal sleeve section 21 and the distal sleeve section 25 do not expand. This allows for a configuration in which at least a portion of the proximal sleeve section 21 is fixed to the distal end of the shaft 30, and at least a portion of the distal sleeve section 25 is fixed to the inner shaft 60, which will be described later.

[0047] The first-layer rich portion 20A and the second-layer rich portion 20B preferably extend along the longitudinal axis direction x1. The first-layer rich portion 20A and the second-layer rich portion 20B may extend linearly or spirally along the longitudinal axis direction x1.

[0048] The first layer rich region 20A and the second layer rich region 20B preferably extend along the entire straight tube portion 23 along the longitudinal axis direction x1. This makes it easier to align the most expandable portion of the balloon 20 along the inner wall of the stenotic region. Alternatively, the first layer rich region 20A and the second layer rich region 20B may extend from the straight tube portion 23 to the proximal tapered region 22 and / or the distal tapered region 24.

[0049] Next, a manufacturing method of the balloon 20 according to an embodiment of the present invention will be described with reference to FIGS. 5 to 9. FIG. 5 is a perspective view of a parison before stretching according to an embodiment of the present invention. FIG. 6 is a cross-sectional view taken along line VI-VI of the parison shown in FIG. 5, and is a cross-sectional view of a parison used to manufacture a balloon having the cross-section shown in FIG. 2. FIG. 7 is a cross-sectional view perpendicular to the longitudinal axis of a parison mold used to manufacture the parison shown in FIG. 6. FIG. 8 is a cross-sectional view taken along the longitudinal axis of a mold according to an embodiment of the present invention used when stretching the parison. FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8.

[0050] First, the parison 200 is prepared. The parison 200 is made of resin and is a cylindrical member having an inner cavity 205, as shown in FIG. 5 . The parison 200 has a first end 201 and a second end 202, and extends in a longitudinal axis direction x2 from the first end 201 to the second end 202. Like the balloon 20, the parison 200 has a radial direction y2 and a circumferential direction z2.

[0051] 6, the parison 200 includes a second layer 200b and a first layer 200a made of a material having a lower Shore D hardness than the second layer 200b. The first layer 200a and the second layer 200b are preferably continuous throughout the circumferential direction z2. For the materials and Shore D hardnesses of the first and second layers 200a and 200b, please refer to the description of the resins used to make the first and second layers 20a and 20b of the balloon 20.

[0052] 6, in a cross section perpendicular to the longitudinal axis direction x2, the first layer 200a preferably has a thick portion 200A and a thin portion 200B in the radial direction y2. From the viewpoint of the thickness of the second layer 200b, it is preferable that the thickness of the second layer 200b in the radial direction y2 is thin in the portion 200A and that the thickness of the second layer 200b in the radial direction y2 is thick in the portion 200B.

[0053] Such a parison 200 can be manufactured by extrusion molding a resin using, for example, a parison mold 250 as shown in Fig. 7. As shown in Fig. 7, the parison mold 250 has a first tubular member 251, a second tubular member 252, and a third tubular member 253. The first tubular member 251 has a cylindrical shape so as to form the inner cavity 205 of the parison 200, the second tubular member 252 has a gear-like shape so as to form the portion 200A and the portion 200B, and the third tubular member 253 preferably has a cylindrical shape so as to form the parison 200 in a cylindrical shape. This allows a cylindrical parison 200 having an inner cavity 205, a portion 200A, and a portion 200B to be manufactured by introducing a resin that forms the first layer 200a into the space between the outer surface of the first tubular member 251 and the inner surface of the second tubular member 252, and introducing a resin that forms the second layer 200b into the space between the outer surface of the second tubular member 252 and the inner surface of the third tubular member 253 and extruding the resin.

[0054] The material constituting the parison mold 250 is preferably a metal, and more preferably iron, copper, aluminum, or an alloy thereof. For example, an iron alloy may be stainless steel, a copper alloy may be brass, and an aluminum alloy may be duralumin. In terms of sufficient strength and ease of processing, the parison mold 250 is preferably made of stainless steel.

[0055] By stretching the parison 200, a balloon 20 can be produced, which has a first layer 20a and a second layer 20b, and in which the thickness variation rate of the first layer 20a in the circumferential direction z1 is equal to or greater than a predetermined value. A mold 300 such as that shown in FIG. 8 can be used for this purpose. The mold 300 has a longitudinal axis direction x3, a radial direction y3, and a circumferential direction z3, and has a lumen 305 extending in the longitudinal axis direction x3 and into which the parison 200 is inserted. It is preferable that a portion of the parison 200 in the longitudinal axis direction x2 is disposed in the lumen 305 of the mold 300. Stretching the parison 200 may be performed by blow molding the parison 200, or by biaxially stretching the parison 200.

[0056] The mold 300 preferably has, in the longitudinal axis direction x3, a mold straight pipe section 300C that forms the straight pipe section 23 of the balloon 20, two mold tapered sections 300T that are arranged on both sides of the mold straight pipe section 300C and form tapered sections of the balloon 20, and two mold sleeve sections 300S that are arranged further away from the mold tapered sections 300T than the mold straight pipe section 300C and form sleeve sections of the balloon 20. As a result, the mold straight pipe section 300C can form the straight pipe section 23 of the balloon 20, the mold tapered sections 300T can form the proximal tapered section 22 and the distal tapered section 24, and the mold sleeve sections 300S can form the proximal sleeve section 21 and the distal sleeve section 25.

[0057] The mold 300 may be composed of a single member or multiple members. As shown in FIG. 8 , multiple mold members may be connected to each other in the longitudinal axis direction x3. For example, the mold straight tube section 300C, the mold tapered section 300T, and the mold sleeve section 300S may each be different mold members connected to each other in the longitudinal axis direction x3. The mold 300 may also be separable in the radial direction y. This facilitates inserting the parison 200 into the cavity 305 of the mold 300. As shown in FIG. 8 , the mold members may be joined by engaging adjacent mold members with each other, or, although not shown, adjacent mold members may be attached with magnets and joined by magnetic attraction.

[0058] 9, the cavity 305 of the mold 300 is preferably formed in a substantially circular shape. By placing the parison 200 in this cavity 305 and introducing a fluid into the cavity 205 of the parison 200 to stretch it, a balloon 20 can be manufactured with a film thickness variation rate of a predetermined value or less.

[0059] The material constituting the mold 300 is preferably a metal, and more preferably iron, copper, aluminum, or an alloy thereof. For example, an iron alloy may be stainless steel, a copper alloy may be brass, and an aluminum alloy may be duralumin. From the viewpoints of sufficient strength and ease of processing, the mold 300 is preferably made of stainless steel.

[0060] 2. Balloon Catheter The balloon catheter 10 according to the embodiment of the present invention includes the balloon for balloon catheter 20. As described in the above section "1. Balloon for Balloon Catheter," the balloon 20 is connected to the distal end of the shaft 30, as shown in FIG.

[0061] 1 shows a so-called rapid exchange type balloon catheter 10 having a guidewire port 61 midway from the distal side to the proximal side of the shaft 30 and an inner shaft 60 that functions as a guidewire passageway from the guidewire port 61 to the distal end of the shaft 30. The balloon catheter 10 preferably has a distal shaft 31 and a proximal shaft 32, and the distal shaft 31 and the proximal shaft 32 may be separate members, with the proximal end of the distal shaft 31 connected to the distal end of the proximal shaft 32 to form the shaft 30 that extends from the balloon 20 to the proximal end of the balloon catheter 10. Alternatively, a single shaft 30 may extend from the balloon 20 to the proximal end of the balloon catheter 10, and the distal shaft 31 and the proximal shaft 32 may each be composed of multiple tubular members.

[0062] The shaft 30 preferably has a fluid flow path and a guidewire insertion path therein. To configure the shaft 30 to have a fluid flow path and a guidewire insertion path therein, for example, an inner shaft 60 disposed inside the shaft 30 may function as a guidewire insertion path, and the space between the shaft 30 and the inner shaft 60 may function as a fluid flow path. In such a configuration, it is preferable that the inner shaft 60 extends from the distal end of the shaft 30 and passes through the balloon 20, and the distal side of the balloon 20 is connected to the inner shaft 60, and the proximal side of the balloon 20 is connected to the shaft 30.

[0063] The shaft 30 is preferably made of resin, metal, or a combination of resin and metal. Using resin as the shaft's constituent material makes it easier to impart flexibility and elasticity to the shaft 30. Furthermore, using metal as the shaft's constituent material can improve the deliverability of the balloon catheter 10. Examples of resins that can be used to form the shaft 30 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluorine-containing resins, vinyl chloride resins, silicone resins, natural rubber, and synthetic rubber. These may be used alone or in combination. Examples of metals that can be used to form the shaft 30 include stainless steels such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloys, Co-Cr alloys, or combinations thereof. When the shaft 30 is composed of a distal shaft 31 and a proximal shaft 32 that are separate members, the distal shaft 31 may be made of resin, and the proximal shaft 32 may be made of metal, for example. The shaft 30 may also have a laminated construction of different materials or the same materials.

[0064] The balloon 20 and the shaft 30 can be joined by bonding with an adhesive, welding, or by attaching a ring-shaped member to the overlapping portion of the end of the balloon 20 and the shaft 30 and crimping the end. Among these, it is preferable that the balloon 20 and the shaft 30 are joined by welding. By welding the balloon 20 and the shaft 30, the bond between the balloon 20 and the shaft 30 is less likely to come loose even when the balloon 20 is repeatedly expanded or contracted, and the bond strength can be improved.

[0065] A tip member 70 is preferably provided at the distal end of the balloon catheter 10. The tip member 70 may be provided at the distal end of the balloon catheter 10 as a separate member from the inner shaft 60 and connected to the distal end of the balloon 20, or the inner shaft 60 may extend distally beyond the distal end of the balloon 20 and function as the tip member 70.

[0066] Radiopaque markers 80 may be placed on the inner shaft 60 inside the balloon 20 at the location of the balloon 20 in the longitudinal axis direction x1 so that the position of the balloon 20 can be confirmed under X-ray fluoroscopy. The radiopaque markers 80 are preferably placed at positions corresponding to both ends of the straight tube section 23 of the balloon 20, or may be placed at a position corresponding to the center of the straight tube section 23 in the longitudinal axis direction x1.

[0067] A hub 40 may be provided on the proximal side of the shaft 30, and the hub 40 preferably has a fluid injection section 50 that communicates with a flow path for fluid supplied inside the balloon 20.

[0068] The shaft 30 and the hub 40 can be joined by, for example, bonding with an adhesive, welding, etc. Among these, it is preferable that the shaft 30 and the hub 40 are joined by adhesive. By bonding the shaft 30 and the hub 40 together, the bond strength between the shaft 30 and the hub 40 can be increased, thereby improving the durability of the balloon catheter 10, even when the shaft 30 and the hub 40 are made of different materials, such as when the shaft 30 is made of a highly flexible material and the hub 40 is made of a highly rigid material.

[0069] Although not shown, the present invention can also be applied to so-called over-the-wire balloon catheters, which have a guidewire passage extending from the distal to the proximal side of the shaft. In the case of over-the-wire balloon catheters, the inflation lumen and the guidewire lumen preferably extend to a hub located proximally, and the proximal openings of each lumen are preferably provided in a bifurcated hub.

[0070] In the case of a rapid exchange type catheter, it is preferable that an appropriate coating is applied to the outer wall of the distal shaft 31 and / or the proximal shaft 32, and it is more preferable that a coating is applied to both the distal shaft 31 and the proximal shaft 32. In the case of an over-the-wire type catheter, it is preferable that an appropriate coating is applied to the outer wall of the outer shaft.

[0071] The coating can be a hydrophilic coating or a hydrophobic coating depending on the purpose, and can be applied by immersing the shaft 30 in a hydrophilic or hydrophobic coating agent, by applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 30, or by covering the outer wall of the shaft 30 with a hydrophilic or hydrophobic coating agent. The coating agent may contain drugs or additives.

[0072] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, methyl vinyl ether maleic anhydride copolymer, and the like, or hydrophilic coating agents made from any combination thereof.

[0073] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0074] This application claims the benefit of priority based on Japanese Patent Application No. 2022-184271, filed on November 17, 2022. The entire contents of the specification of Japanese Patent Application No. 2022-184271, filed on November 17, 2022, are incorporated herein by reference.

[0075] 10: Balloon catheter 20: Balloon for balloon catheter 20a: First layer 20A: First layer rich portion 20b: Second layer 20B: Second layer rich portion 20C: Centroid of outer edge of balloon 20M: Balloon membrane 30: Shaft 31: Distal shaft 32: Proximal shaft 40: Hub 50: Fluid injection portion 60: Inner shaft 61: Guidewire port 70: Tip member 80: Marker 200: Parison 200a: First layer of parison 200b: Second layer of parison 201: First end of parison 202: Second end of parison 205: Inner cavity of parison 250: Mold for parison 251: First tubular member 252: Second tubular member 253: Third tubular member 300: Mold 300C: Mold straight tube portion 300S: Mold sleeve portion 300T: Mold tapered portion 305: Mold cavity

Claims

1. A balloon for a balloon catheter, having a balloon membrane having a longitudinal axis direction, a radial direction, and a circumferential direction, the balloon membrane including a first layer and a second layer made of a material having a Shore D hardness higher than that of the first layer, When the balloon for the balloon catheter is in an expanded state, the first layer and the second layer are disposed over 360° in the circumferential direction, the second layer is located radially outward of the first layer, In the expanded state of the balloon catheter balloon, in a cross section perpendicular to the longitudinal axis direction, the rate of change ((|Tx-Ta| / Ta) × 100) of the thickness Tx of the balloon membrane at any position x in the circumferential direction relative to the average thickness Ta of the balloon membrane is 15% or less, The first layer has an average thickness T1a of 2 μm or more, A balloon for a balloon catheter, having a position X1 in a cross section perpendicular to the longitudinal axis direction, where the rate of change ((|T1x-T1a| / T1a) x 100) of the thickness T1x of the first layer at the circumferential position X1 relative to the average thickness T1a of the first layer is 20% or more.

2. 2. The balloon for a balloon catheter according to claim 1, wherein, in a cross section perpendicular to the longitudinal axis direction, when the 360° circumferential direction is divided into first, second, and third quadrants each having an interval of 120°, there is a position X1 in each quadrant where the rate of change ((|T1x-T1a| / T1a)×100) of the thickness T1x of the first layer at the circumferential position X1 relative to the average thickness T1a of the first layer is 20% or more.

3. 3. The balloon for a balloon catheter according to claim 2, wherein each of the first, second, and third quadrants has a first-layer rich portion in which the thickness T1x of the first layer is greater than 50% of the thickness Tx1 of the balloon membrane at the position X1, and a second-layer rich portion in which the thickness T2x of the second layer at the circumferential position X2 is greater than 50% of the thickness Tx2 of the balloon membrane at the position X2.

4. In the circumferential direction of each of the quadrants, a plurality of the first layer-rich portions and a plurality of the second layer-rich portions are respectively arranged, the total of the ranges where the first layer-rich portions are arranged is 30° or more out of 120° in the circumferential direction of each quadrant, the total of the ranges where the second layer-rich portions are arranged is 30° or more out of 120° in the circumferential direction of each quadrant, and the first layer-rich portions and the second layer-rich portions are arranged alternately in the circumferential direction. The balloon for a balloon catheter according to claim 3.

5. A first layer-rich portion in which the film thickness T1x of the first layer is more than 50% of the film thickness Tx1 of the balloon film at the circumferential position X1 of the balloon film, and a second layer-rich portion in which the film thickness T2x of the second layer at the circumferential position X2 is more than 50% of the film thickness Tx2 of the balloon film at the position X2 of the balloon film. In the circumferential direction, a plurality of the first layer-rich portions and a plurality of the second layer-rich portions are respectively arranged, the range where each one of the first layer-rich portions and the second layer-rich portions is arranged is 15° or more out of 360° in the circumferential direction of the balloon film, and the first layer-rich portions and the second layer-rich portions are arranged alternately. The balloon for a balloon catheter according to claim 1.

6. A balloon catheter comprising the balloon for a balloon catheter according to any one of claims 1 to 5.