Cutting device and cutting system

Abstract

This invention provides a cutting device and a cutting system. The cutting device includes an expandable structure having a radially expanded state and a radially contracted state, for fitting over the balloon of a balloon catheter. The expandable structure includes a cutting portion and a flexible portion along its axial direction, the flexible portion being connected to the axial end of the cutting portion. The cutting device and cutting system of this invention can reduce the probability of disordered tearing of the vascular intima by the balloon, thereby reducing the probability of flow-limiting dissection.

Description

Technical Field

[0001] This invention relates to the field of interventional medical device technology, and in particular to a cutting device and cutting system. Background Technology

[0002] From the 1970s to the present, interventional vascular treatment technology has experienced rapid and vigorous development. Balloon angioplasty is one of the fundamental procedures in the endovascular treatment of lower extremity arteriosclerosis obliterans. Common balloons include notched balloons, standard balloons (POBA), and drug-coated peripheral balloons (DCB).

[0003] The principle of balloon angioplasty is as follows: When an artery is narrowed, the location, diameter, and length of the narrowing are confirmed by angiography. Then, a balloon catheter of appropriate size is selected. A sheath is first inserted to establish a channel, and a guidewire is inserted to establish a track. The balloon dilation catheter then advances externally along this channel and track until the distal end of the catheter passes the narrowed segment (aligning the balloon with the narrowed segment). An additional pressure dilation device is used to apply pressure to the balloon catheter, causing the balloon to inflate. The balloon dilation compresses the narrowed segment, converting its internal pressure into expansion force, causing atherosclerotic material and plaque in the narrowed segment to be deformed and adhere to the inner wall of the blood vessel. Further inflation of the balloon causes appropriate tearing of the smooth muscle in the vessel wall, further widening the vessel and its lumen. After maintaining this position for a period of time (approximately tens of seconds to several minutes), the balloon pressure is released and the balloon is withdrawn along the guidewire and channel. Finally, the lumen of the narrowed segment of the blood vessel is widened, restoring good blood supply.

[0004] In clinical practice, commercially available balloons provide uniform pressure to the surrounding area. Their principle of vasodilation is to continuously expand and compress narrowed blood vessels by inflating the balloon. This often easily causes disordered tearing of the vascular intima, resulting in flow-limiting dissection. Summary of the Invention

[0005] This invention provides a cutting device and cutting system to reduce the probability of disordered tearing of the vascular intima by a balloon, thereby reducing the probability of flow-limiting dissection.

[0006] The present invention provides a cutting device, comprising: an expandable structure having a radially expanded state and a radially contracted state, for being fitted over the balloon of a balloon catheter; the expandable structure includes a cutting portion and a flexible portion along the axial direction, the flexible portion being connected to the axial end of the cutting portion.

[0007] In one embodiment, the cutting portion includes a plurality of cutting units spaced circumferentially along the expandable structure, and the flexible portion includes a plurality of flexible rods spaced circumferentially along the expandable structure, wherein the flexible rods and the cutting units both extend axially along the expandable structure.

[0008] In one embodiment, the normal bending stiffness of the flexible rod is less than the normal bending stiffness of the cutting unit.

[0009] In one embodiment, the flexible rod and the cutting unit are made of the same material, the thickness of the flexible rod is less than or equal to the thickness of the cutting unit, and the cross-sectional area of ​​the flexible rod is less than the cross-sectional area of ​​the cutting unit.

[0010] In one embodiment, the elastic modulus of the flexible rod is less than that of the cutting unit, the thickness of the flexible rod is less than or equal to the thickness of the cutting unit, and the cross-sectional area of ​​the flexible rod is less than or equal to the cross-sectional area of ​​the cutting unit.

[0011] In one embodiment, the ratio of the minimum width of the cutting unit to the maximum width of the flexible rod ranges from 1.2 to 5, and the ratio of the length of the flexible rod to the length of the cutting unit ranges from 0.5 to 2.

[0012] In one embodiment, the flexible rod is a straight rod, and the maximum gap width between two circumferentially adjacent flexible rods is greater than the maximum gap width between two circumferentially adjacent cutting units.

[0013] In one embodiment, each of the cutting units includes a cutting edge and a non-cutting edge; when the expandable structure is in a radially contracted state, the cutting edge and the non-cutting edge are arranged circumferentially along the expandable structure, and when the expandable structure is in a radially expanded state, the cutting edge is further away from the inner cavity of the expandable structure relative to the non-cutting edge.

[0014] In one embodiment, the inner wall of the cutting unit is provided with a protruding unit. When the expandable structure is in a radially contracted state, the protruding unit protrudes towards a direction closer to the inner cavity of the expandable structure compared to other areas of the expandable structure. Along the width direction of the cutting unit, the protruding unit is closer to the cutting edge of the cutting unit and further away from the non-cutting edge of the cutting unit.

[0015] The present invention also provides a cutting system, including a balloon catheter and the cutting device described in any of the above claims, wherein the cutting device can be detachably sleeved on the outside of the balloon catheter.

[0016] The present invention discloses a cutting device and a cutting system. The cutting device comprises an expandable structure having a radially expanded state and a radially contracted state, for fitting over the balloon of a balloon catheter. The expandable structure includes a cutting portion and a flexible portion along its axial direction, the flexible portion being connected to the axial end of the cutting portion. The cutting portion can locally cut the inner wall of the blood vessel, achieving orderly tearing of the intima at the cut site. This reduces the probability of disordered tearing of the intima by the balloon, thereby reducing the probability of flow-limiting dissection and also reducing the degree of post-treatment vascular retraction. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the cutting system in one embodiment of the present invention;

[0018] Figure 2 This is a partial planar unfolded schematic diagram of an expandable structure in a radially contracted state according to an embodiment of the present invention;

[0019] Figure 3 This is a partial planar unfolding schematic diagram of the expandable structure in a radially contracted state according to another embodiment of the present invention;

[0020] Figure 4 for Figure 3 A partially enlarged schematic diagram of the expandable structure;

[0021] Figure 5 This is a partial structural diagram of the expandable structure following the inflation of the balloon in one embodiment of the present invention;

[0022] Figure 6 This is a schematic cross-sectional view of the cutting unit at the cutting teeth in one embodiment of the present invention;

[0023] Figure 7 This is a partial planar unfolding schematic diagram of the expandable structure in a radially contracted state according to another embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of the balloon in an inflated state according to one embodiment of the present invention. Detailed Implementation

[0025] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0026] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] In the field of interventional medical devices, the end of a medical device implanted in the human or animal body that is closer to the operator is generally called the "proximal end," and the end that is farther from the operator is called the "distal end." Based on this principle, the "proximal end" and "distal end" of any component of a medical device are defined. "Axial" refers to its length direction, and "radial" refers to the direction perpendicular to the "axial" direction.

[0029] Reference Figure 1 The cutting system 100 provided in this embodiment includes a cutting device 20 and a balloon catheter 10. In this embodiment, the cutting device 20 can be detachably sleeved on the balloon catheter 10. During use, the operator can select a suitable cutting device 20 and balloon catheter 10 for use according to actual needs.

[0030] The cutting device 20 includes an expandable structure 21 with an inner cavity, which can be radially expanded into a mesh structure. The expandable structure 21 can be cut from one or more materials, such as elastic materials, shape memory metals like nickel-titanium alloys, stainless steel, and polymer materials. In other embodiments, the individual components of the expandable structure 21 can be manufactured separately and then spliced ​​together.

[0031] The balloon catheter 10 may include a balloon 11, which has an inner lumen. The radial expansion and contraction of the balloon 11 can be controlled by injecting a medium (liquid or gas, etc.) into and withdrawing the medium from the inner lumen of the balloon 11. The inner lumen of the expandable structure 21 of the cutting device 20 can accommodate the balloon 11, meaning the expandable structure 21 can be fitted over the outside of the balloon 11. After the expandable structure 21 is fitted over the outside of the balloon 11, when the balloon 11 is in a radially contracted state, the expandable structure 21 is also in a radially contracted state. When the balloon 11 expands radially, it can cause the expandable structure 21 to expand radially, thereby dilating the narrowed vascular segment.

[0032] Reference Figure 1 , Figure 2 In this embodiment, the expandable structure 21 includes one or more cutting portions 30, which are used to apply a large compressive force to a local area of ​​the vascular intima when the expandable structure 21 is in a radially expanded state, thereby achieving directional and uniform tearing of the local area of ​​the vascular intima, reducing the probability of disordered tearing of the vascular intima, and thus reducing the probability of flow-limiting dissection. When the expandable structure 21 includes multiple cutting portions 30, the multiple cutting portions 30 are arranged sequentially along the axial direction of the expandable structure 21.

[0033] Because the expandable structure 21 is equipped with a cutting section 30, the cutting section 30 itself needs to possess a certain mechanical strength to achieve cutting. When the cutting device 20 passes through some relatively curved conveying channels, the cutting section 30, in order to conform to the curved conveying channels, may tilt up, posing a risk of scratching the tube wall or blood vessel wall of the conveyor. In this embodiment, the expandable structure 21 also includes one or more flexible sections 50, which are connected to the axial end of the cutting section 30. By providing the flexible section 50, the flexible section 50 can bend and deform before the cutting section 30 when passing through relatively curved conveying channels to adapt to the curved conveying channels, thereby reducing the probability of the cutting section 30 tilting up and thus reducing the risk of scratching the tube wall or blood vessel wall of the conveyor.

[0034] The cutting section 30 includes a plurality of cutting units 31 arranged circumferentially along the expandable structure 21, and the flexible section 50 includes a plurality of flexible rods 51 arranged circumferentially along the expandable structure 21. Both the flexible rods 51 and the cutting units 31 extend axially along the expandable structure 21.

[0035] For example, the cutting unit 31 may be an elongated sheet-like structure, including two opposing side edges along its width direction. When the expandable structure 21 is in a radially contracted state, the two side edges of the cutting unit 31 are arranged circumferentially along the expandable structure 21, and the two side surfaces of the cutting unit 31 in the thickness direction are arranged approximately at intervals along the radial direction of the expandable structure 21, so that the outer and inner surfaces of the expandable structure 21 are relatively flat when it is in a radially contracted state, avoiding scratching the outer sheath and balloon 11 of the delivery device during delivery. When the expandable structure 21 is in an expanded state, one side edge of the cutting unit 31 is further away from the inner lumen of the expandable structure 21 than the other side edge, so that the side edge away from the inner lumen of the expandable structure 21 can better contact the inner wall of the blood vessel and form a local cut on the inner wall of the blood vessel. The intima of the blood vessel at the cut portion 30 can achieve orderly tearing, thereby reducing the probability of disordered tearing of the intima by the balloon 11, thereby reducing the probability of flow-limiting dissection, and also reducing the degree of vascular retraction after treatment.

[0036] The flexibility of the flexible rod 51 of the flexible part 50 is better than that of the cutting unit 31. Therefore, it can bend and deform before the cutting unit 31 when passing through a more curved conveying channel.

[0037] The flexibility of the flexible rod 51 in the flexible part 50 is superior to that of the cutting unit 31, which can be achieved in one or more of the following ways:

[0038] Method 1: The normal bending stiffness of the flexible rod 51 is less than that of the cutting unit 31. The normal direction of the flexible rod 51 refers to the thickness direction of the flexible rod 51, and the normal direction of the cutting unit 31 refers to the thickness direction of the cutting unit 31, which is also the radial direction of the expansion structure 21.

[0039] Method 2: The flexible rod 51 and the cutting unit 31 are made of the same material. The thickness of the flexible rod 51 is less than or equal to the thickness of the cutting unit 31 (that is, the thickness of any segment of the flexible rod 51 is less than the thickness of any segment of the cutting unit 31), and the cross-sectional area of ​​the flexible rod 51 is less than the cross-sectional area of ​​the cutting unit 31 (that is, any cross-sectional area of ​​the flexible rod 51 is less than any cross-sectional area of ​​the cutting unit 31).

[0040] Method 3: The elastic modulus of the flexible rod 51 is less than the elastic modulus of the cutting unit 31, the thickness of the flexible rod 51 is less than or equal to the thickness of the cutting unit 31 (i.e., the thickness of any segment of the flexible rod 51 is less than the thickness of any segment of the cutting unit 31), and the cross-sectional area of ​​the flexible rod 51 is less than or equal to the cross-sectional area of ​​the cutting unit 31 (i.e., any cross-sectional area of ​​the flexible rod 51 is less than any cross-sectional area of ​​the cutting unit 31).

[0041] Method 4: Insert the balloon 11, which is matched with the cutting device 20, into the inner cavity of the expandable structure 21, and inject a medium (liquid or gas, etc.) into the inner cavity of the balloon 11 to gradually increase the pressure of the balloon 11 from 0 atm to the nominal pressure (usually 6 atm to 10 atm). During the gradual expansion of the balloon 11, the flexible part 50 deforms in the radial direction of the expandable structure 21 before the cutting part 30. In other words, when the flexible part 50 undergoes initial deformation in the radial direction of the expandable structure 21, the pressure value of the balloon 11 is less than when the cutting part 30 undergoes initial deformation in the radial direction of the expandable structure 21.

[0042] For example, in this embodiment, the flexible rod 51 and the cutting unit 31 are integrally cut from the same material. The thickness of the flexible rod 51 is substantially equal to the thickness of the cutting unit 31 (substantially equal means that the ratio of the absolute value of the difference between the two values ​​to the average value of the two values ​​is less than 10%). The flexible rod 51 has a relatively uniform width (i.e., the dimension of the flexible rod 51 along the circumferential direction of the expandable structure 21). The width of the flexible rod 51 (the width of any segment of the flexible rod 51) is less than the minimum width of the cutting unit 31. This configuration makes the flexibility of the flexible rod 51 better than that of the cutting unit 31. The normal bending stiffness of the flexible rod 51 is less than that of the cutting unit 31. Furthermore, during the expansion of the balloon 11, the flexible rod 51 deforms radially along the expandable structure 21 before the cutting unit 31.

[0043] The ratio of the minimum width of the cutting unit 31 to the maximum width of the flexible rod 51 can range from 1.2 to 5. For example, when the minimum width of the cutting unit 31 is 0.4 mm, the maximum width of the flexible rod 51 can be 0.15 mm. The ratio of the length of the flexible rod 51 to the length of the cutting unit 31 can range from 0.5 to 2. For example, the length of the flexible rod 51 can be 2 mm, and the length of the cutting unit 31 can be 3 mm. By reasonably setting the dimensions of the cutting unit 31 and the flexible rod 51, it is beneficial to maintain the flexible rod 51 with good flexibility while also having good mechanical strength, ensuring that it has certain anti-torsional and anti-tensile properties when the cutting unit 31 flips over, and reducing the risk of damage or breakage of the flexible rod 51 during the radial expansion of the expandable structure 21. It is understood that in other embodiments, the dimensions of the cutting unit 31 and the flexible rod 51 may differ from the ranges exemplified above, and those skilled in the art can set them as needed.

[0044] The aforementioned flexible rod 51 can be one or more of a straight rod, a wavy rod, an arc-shaped rod, or a helical rod. Among them, the gap width between adjacent straight rods is larger than that of wavy rods, arc-shaped rods, and helical rods. On the one hand, it can provide a larger deformation space when the expandable structure 21 bends, making it easier to adapt to bending deformation. On the other hand, during the process of the expandable structure 21 changing from a radially expanding state to a radially contracting state, it can reduce the risk that the balloon 11 will be trapped in the gap, causing the flexible part 50 to fail to recover the radial contraction state well.

[0045] In this embodiment, the maximum gap width between two circumferentially adjacent flexible rods 51 can be greater than the maximum gap width between two circumferentially adjacent cutting units 31. This arrangement allows the flexible rods 51 to have greater deformation space when the expandable structure 21 bends, making them more adaptable to bending deformation. This further reduces the probability of the cutting part 30 bending and warping during the passage of the cutting device 20 through a curved conveying channel, thereby reducing the risk of scratching the walls of the conveyor or blood vessels.

[0046] In this embodiment, the number of flexible rods 51 in a single flexible section 50 is the same as the number of cutting units 31 in a single cutting section 30, both being 6. In other embodiments, the number of flexible rods 51 in a single flexible section 50 and the number of cutting units 31 in a single cutting section 30 may be different, and the number of flexible rods 51 in a single flexible section 50 and the number of cutting units 31 in a single cutting section 30 may be less than 6 or more than 6. For example, the number of flexible rods 51 in a single flexible section 50 and the number of cutting units 31 in a single cutting section 30 may be selected from any one of 3, 4, 5, 7, 8, 9, or 10, and those skilled in the art can choose according to actual needs.

[0047] In this embodiment, the outer diameter of the flexible part 50 is substantially equal to the outer diameter of the cutting part 30, and the inner diameter of the flexible part 50 is also substantially equal to the inner diameter of the cutting part 30. In other embodiments, the outer diameter of the flexible part 50 may not be equal to the outer diameter of the cutting part 30, and the inner diameter of the flexible part 50 may also not be equal to the inner diameter of the cutting part 30.

[0048] Reference Figure 3 The cutting section 30 includes a cutting unit 31, a connecting node 32, and a connecting section 33. Unlike... Figure 2 Either side of the cutting unit 31 shown can be used for cutting. In another embodiment of this invention, refer to... Figure 3 , Figure 4 Each cutting unit 31 includes a cutting edge 311 and a non-cutting edge 312.

[0049] For example, the cutting unit 31 may be an elongated sheet structure, with the cutting edge 311 and the non-cutting edge 312 being the two opposite edges in the width direction of the cutting unit 31. When the expandable structure 21 is in a radially contracted state, the cutting edge 311 and the non-cutting edge 312 are arranged circumferentially along the expandable structure 21, and the two sides in the thickness direction of the cutting unit 31 are arranged at intervals approximately along the radial direction of the expandable structure 21, so that the outer and inner surfaces of the expandable structure 21 are relatively flat in the radially contracted state, avoiding scratching the outer sheath and balloon 11 of the conveyor during the conveying process.

[0050] Please refer to Figure 5During the radial expansion of the expandable structure 21, the cutting edge 311 of the cutting unit 31 is oriented to flip away from the inner cavity of the expandable structure 21, while the non-cutting edge 312 is oriented to flip closer to the inner cavity of the expandable structure 21. That is, the cutting edge 311 flips outward, and the non-cutting edge 312 flips inward. When the expandable structure 21 is in a radially expanding state, the cutting edge 311 of the cutting unit 31 is further away from the inner cavity of the expandable structure 21 than the non-cutting edge 312. "Oriented flipping" means that during the transition of the expandable structure 21 from a radially contracted state to a radially expanding state (i.e., the radial expansion process), once the cutting unit 31 flips, it will only flip in a predetermined direction. "Non-oriented flipping" means that during the transition of the expandable structure 21 from a radially contracted state to a radially expanding state (i.e., the radial expansion process), the direction in which the cutting unit 31 flips is uncertain. For non-directional flipping, it is possible that when the expandable structure 21 is in a radially expanded state, the cutting edge 311 of the cutting unit 31 is closer to the inner cavity of the expandable structure 21 than the non-cutting edge 312.

[0051] Compared to non-directional flipping, in this embodiment, because the cutting unit 31 can achieve directional flipping during the expansion of the expandable structure 21, when the expandable structure 21 is in the expanded state, the cutting edge 311 is farther away from the lumen of the expandable structure 21 than the non-cutting edge 312. The cutting edge 311 can better contact the inner wall of the blood vessel and form a local cut, allowing for orderly tearing of the intima at the cut portion 30. This reduces the probability of disordered tearing of the intima by the balloon 11, thereby reducing the probability of flow-limiting dissection and the degree of post-treatment vascular retraction. Furthermore, the non-cutting edge 312 flips towards the lumen of the expandable structure 21, thus reducing the probability of balloon 11 damage caused by the non-directional flipping of the cutting edge 311 towards the lumen of the expandable structure 21. Compared to... Figure 2 Either of the two sides shown can be used for cutting. Figures 3-4 The cutting edge 311 in the middle can be made sharper, with better cutting effect and less likely to damage the balloon 11.

[0052] like Figures 3 to 5As shown, the cutting section 30 may include multiple cutting units 31, which are spaced apart circumferentially along the expandable structure 21. For example, in this embodiment, the cutting section 30 is generally tubular with a roughly circular cross-sectional profile, and the multiple cutting units 31 are evenly spaced along the circumferential direction of the expandable structure 21. By evenly spaced multiple cutting units 31, it is beneficial to cut the inner wall of the blood vessel evenly and efficiently in the circumferential direction, so that the intima of the blood vessel can be better to achieve orderly tearing. The cutting edge 311 of the cutting unit 31 includes one or more of the following: toothed structure, spiked structure, blade structure, and wavy structure. For example, the cutting edge 311 in this embodiment includes a toothed structure or a wavy structure. When cutting the inner wall of the blood vessel, the toothed structure or the wavy structure can apply greater local pressure to the inner wall of the blood vessel, thereby effectively treating severe calcified lesions. In addition, the tips of the toothed structure or the wavy structure are not too sharp, so even if they touch the balloon 11, the balloon 11 will not be immediately damaged. Understandably, when there are multiple cutting sections 30 in the expandable structure 21, the structures of each cutting section 30 may be the same or different. For example, the number and structure of cutting units 31 in each cutting section 30 may be the same or different.

[0053] The cutting unit 31 extends along the axial direction of the expandable structure 21. The cutting unit 31 may be substantially parallel to the axis of the expandable structure 21 or there may be an angle between the cutting unit 31 and the axis of the expandable structure 21.

[0054] Along the circumference of the expandable structure 21, each cutting unit 31 has a cutting gap 34 extending axially along both sides of the expandable structure 21. The axial end of the cutting unit 31 is connected to a corresponding connecting node 32 via at least one connecting part 33 (e.g., fixed connection). One axial side of the connecting node 32 is connected to the connecting part 33, and the other side of the connecting node 32 is connected to a corresponding flexible rod 51. Both axial ends of each flexible rod 51 are connected to the connecting node 32 in the corresponding cutting part 30.

[0055] Exemplarily, the cutting gap 34 includes a first gap 341 and a second gap 342 communicating with the axial end of the first gap 341. The connecting node 32 is located in the second gap 342 further away from the axial end of the first gap 341. The connecting portion 33 includes a plurality of rod-shaped connecting units 33 arranged sequentially at intervals along the circumferential direction of the expandable structure 21, such as a first connecting unit 331 and a second connecting unit 332. The first connecting unit 331 of one connecting portion 33 and the second connecting unit 332 of another connecting portion circumferentially adjacent to the connecting portion are connected to the same connecting node 32. That is, the first connecting unit 331 and the second connecting unit 332 within the same connecting portion are respectively connected to two circumferentially adjacent connecting nodes 32. Along the circumferential direction of the expandable structure 21, the first connecting unit 331 and the second connecting unit 332 are respectively located on both sides of the second gap 342.

[0056] When the expandable structure 21 is in a radially contracted state, the first connecting unit 331 and the second connecting unit 332 connected to the same cutting unit 31 are arranged circumferentially along the expandable structure 21. When the expandable structure 21 is in a radially expanded state, the side of the first connecting unit 331 closer to the cutting edge 311 in the width direction is located above the side of the first connecting unit 331 closer to the non-cutting edge 312 in the width direction (the so-called above refers to the side further away from the inner cavity of the expandable structure 21 in the radial direction, or the radially outer side). Similarly, the side of the second connecting unit 332 closer to the cutting edge 311 in the width direction is located above the side of the second connecting unit 332 closer to the non-cutting edge 312 in the width direction. In the first connecting unit 331 and the second connecting unit 332 connected to the same cutting unit 31, the axial end of the second connecting unit 332 closer to the cutting unit 31 is located above the axial end of the first connecting unit 331 closer to the cutting unit 31.

[0057] Along the circumference of the expandable structure 21, the connecting node 32 includes a first edge 321 and a second edge 322. An expandable gap 35 extending axially along the expandable structure 21 is provided on each side of the connecting node 32. When the expandable structure 21 is in a radially contracted state, the first edge 321 and the second edge 322 are arranged circumferentially along the expandable structure 21. During the radial expansion of the expandable structure 21, the second edge 322 rotates inward toward the inner cavity of the expandable structure 21, while the first edge 321 rotates outward away from the inner cavity of the expandable structure 21. That is, the second edge 322 rotates inward, and the first edge 321 rotates outward. When the expandable structure 21 is in a radially expanded state, the first edge 321 is further away from the inner cavity of the expandable structure 21 than the second edge 322. The overall rotation of the connecting node 32 during the radial expansion of the expandable structure 21 not only facilitates the transmission of the rotation torque but also reduces the risk of breakage due to stress concentration at the connecting node 32. In the first connecting unit 331 and the second connecting unit 332 connected to the same connecting node 32, the first connecting unit 331 is closer to the first edge 321 than the second connecting unit 332. When the expandable structure 21 is in a radially expanded state, the axial end of the second connecting unit 332 connected to the connecting node 32 (that is, the end closer to the connecting node 32) is located below the axial end of the first connecting unit 331 connected to the connecting node 32 (that is, the end closer to the connecting node 32). (The so-called "below" refers to the side closer to the inner cavity of the expandable structure 21 in the radial direction of the expandable structure 21, or the radial inner side).

[0058] When the expandable structure 21 is in a radially contracted state, the two sides of the flexible rod 51 connected to the connecting node 32 in the width direction (that is, the two sides in the circumferential direction of the expandable structure 21) are arranged circumferentially along the expandable structure 21. When the expandable structure 21 is in a radially expanded state, the side of the flexible rod 51 and the first edge 321 of the connecting node 32 connected to it are located above the side of the flexible rod 51 and the second edge 322 of the connecting node 32 connected to it.

[0059] For example, the cutting section 30 includes a plurality of cutting units 31 arranged circumferentially along the expandable structure 21. Each of the plurality of cutting units 31 has a row of connecting nodes 32 at both ends of its axial direction. Each row of connecting nodes 32 includes a plurality of connecting nodes 32 arranged circumferentially along the expandable structure 21. Each cutting unit 31 has two connecting nodes 32 at each end of its axial direction. Each connecting node 32 is connected to two adjacent cutting units 31 via a connecting section 33. Taking three adjacent cutting units 31 as an example, these three cutting units 31 are a first cutting unit 31a, a second cutting unit 31b, and a third cutting unit 31c. The first cutting unit 31a is located between the second cutting unit 31b and the third cutting unit 31c. The first cutting unit 31a has a first proximal node 32a and a second proximal node 32b closer to the proximal end of the expandable structure 21, and a first distal node 32c and a second distal node 32d closer to the distal end of the expandable structure 21, respectively. The first proximal node 32a and the second proximal node 32b are circumferentially spaced along the expandable structure 21, with the first proximal node 32a being further away from the cutting edge 311 of the first cutting unit 31a than the second proximal node 32b. Similarly, the first distal node 32c and the second distal node 32d are circumferentially spaced along the expandable structure 21, with the first distal node 32c being further away from the cutting edge 311 of the first cutting unit 31a than the second distal node 32d. The first proximal node 32a is connected to the first cutting unit 31a via a first connecting unit 331 and to the second cutting unit 31b via a second connecting unit 332. The proximal end of the first proximal node 32a is connected to the first proximal flexible rod 51a. The first distal node 32c is connected to the first cutting unit 31a via the first connecting unit 331 and to the second cutting unit 31b via the second connecting unit 332. The distal end of the first distal node is connected to the first distal flexible rod 51c. The second proximal node 32b is connected to the first cutting unit 31a via the second connecting unit 332, and to the third cutting unit 31c via the first connecting unit 331. The proximal end of the second proximal node is connected to the second proximal flexible rod 51b. The second distal node 32d is connected to the first cutting unit 31a via the second connecting unit 332, and to the third cutting unit 31c via the first connecting unit 331. The distal end of the second distal node is connected to the second distal flexible rod 51d.Each connecting node 32 connects to a first connecting unit 331 having a first side 3311 and a second side 3312 in its width direction. Each connecting node 32 connects to a second connecting unit 332 having a third side 3321 and a fourth side 3322 in its width direction. The first side 3311, second side 3312, third side 3321, and fourth side 3322 are arranged sequentially along a first direction O1 in the circumferential direction of the expandable structure 21. The first edge 321 and second edge 322 of the connecting node 32 are arranged sequentially along the first direction O1 in the circumferential direction of the expandable structure 21. The cutting edge 311 and non-cutting edge 312 of each cutting unit 31 are located in the expandable structure 21. The components are arranged sequentially along the first direction 01 in the circumferential direction; for example, the first side 3311 and the first edge 321 of the connecting node 32 together form part of the sidewall of the expandable gap 35 located in the second direction 02 of the connecting node 32, the second side 3312 and the non-cutting edge 312 of the cutting unit 31 connected thereto together form part of the sidewall of the cutting gap 34; the third side 3321 and the cutting edge 311 of the cutting unit 31 connected thereto together form part of the sidewall of the cutting gap 34, and the fourth side 3322 and the second edge 322 of the connecting node 32 together form part of the sidewall of the expandable gap 35 located in the first direction 01 of the connecting node 32.

[0060] Reference Figure 5When the expandable structure 21 is in a radially expanded state, the first connecting unit 331 and the second connecting unit 332 connected by the first proximal node 32a, the first connecting unit 331 and the second connecting unit 332 connected by the first distal node 32c, the first cutting unit 31a, and the second cutting unit 31b enclose and form a hexagonal mesh (expanded by the cutting gap 34). Similarly, the first connecting unit 331 and the second connecting unit 332 connected by the second proximal node 32b, and the first connecting unit 331 and the second connecting unit 332 connected by the second distal node 32d... The first cutting unit 31a and the third cutting unit 31c form a hexagonal mesh (extended by the cutting gap 34). A hexagonal mesh (extended by the expandable gap 35 between the first proximal flexible rod 51a and the second proximal flexible rod 51b) is formed between the first proximal flexible rod 51a and the second proximal flexible rod 51b. A rhomboid or quasi-rhomboid mesh (extended by the expandable gap 35 between the first distal flexible rod 51c and the second distal flexible rod 51d) is formed between the first distal flexible rod 51c and the second distal flexible rod 51d. The first edge 321 of each connecting node 32 is farther from the inner cavity of the expandable structure 21 than the second edge 322. At each connecting node 32, the first connecting unit 331 is farther from the inner cavity of the expandable structure 21 than the second connecting unit 332. At each cutting unit 31, the first connecting unit 331 is closer to the inner cavity of the expandable structure 21 than the second connecting unit 332.

[0061] Understandably, in other embodiments, the number of connection nodes 32 corresponding to each cutting unit 31 may differ from that in this embodiment. For example, the first cutting unit 31a may be connected to only one of the first proximal node 32a, the second proximal node 32b, the first distal node 32c, and the second distal node 32d; or the first cutting unit 31a may be connected to only two or three of the first proximal node 32a, the second proximal node 32b, the first distal node 32c, and the second distal node 32d. For example, the first proximal node 32a may be connected to the first cutting unit 31a through the first connection unit 331, while the second proximal node 32b and the first distal node may not be connected to the first cutting unit 31a, and the second distal node may be connected to the first cutting unit 31a through the second connection unit 332.

[0062] In other embodiments, the connecting portion 33 connected to each connecting node 32 is not necessarily connected to the cutting unit 31. It is sufficient that each cutting unit 31 is connected to at least one connecting node 32 via at least one connecting portion 33. For example, in the cutting section 30, each cutting unit 31 is connected to its corresponding connecting node 32 via a connecting portion 33, and among the connecting portions 33 connected to each connecting node 32, at least one connecting portion 33 is not directly connected to the cutting unit 31. Furthermore, in the cutting section 30, the axial ends of two circumferentially adjacent connecting portions 33 that are not directly connected to the cutting unit 31 are connected to each other, while the other axial ends are connected to the corresponding connecting node 32.

[0063] In this embodiment, when the expandable structure 21 is in a radially contracted state, the maximum width of the cutting unit 31 is greater than the maximum width of the connecting node 32 connected to it. This configuration ensures that when the expandable structure 21 is in a radially expanded state, the protrusion height of the cutting unit 31 relative to the outer surface of the balloon 11 is greater than or equal to the protrusion height of the connecting node 32 relative to the outer surface of the balloon 11. This allows the outer surface of the cutting unit 31 to better conform to the inner wall of the blood vessel, thus improving its cutting effect.

[0064] There are several methods for the cutting unit 31 to achieve directional flipping during the radial expansion of the expandable structure 21.

[0065] Reference Figure 6 In some embodiments, the inner wall of the cutting unit 31 (when in a radially contracted state, the side of the cutting unit 31 closer to the inner cavity of the expandable structure 21 in the thickness direction) is provided with a protruding unit 60. When the expandable structure 21 is in a radially contracted state, the protruding unit 60 protrudes towards the inner cavity of the expandable structure 21 compared to other areas of the expandable structure 21. Along the width direction of the cutting unit 31, the protruding unit 60 is closer to the cutting edge 311 of the cutting unit 31 and further away from the non-cutting edge 312 of the cutting unit 31. By providing the protruding unit 60, during the radial expansion of the expandable structure 21, the protruding unit 60 can be subjected to the radial extrusion force of the balloon 11 before other areas of the expandable structure 21. Since the protruding unit 60 is closer to the cutting edge 311, it can drive the cutting edge 311 of the cutting unit 31 to rotate radially outward towards the expandable structure 21, thereby achieving the directional rotation of the cutting unit 31.

[0066] The protruding unit 60 may include one or more protrusions 61. The cross-sectional shape of the protrusion 61 may be circular, elliptical, polygonal (such as triangle, quadrilateral, etc.), strip-shaped, or any suitable shape. One end of the protrusion 61 is fixedly connected to the inner wall of the cutting unit 31, and the other end of the protrusion 61 protrudes toward the inner cavity of the expandable structure 21 when the expandable structure 21 is in a radially contracted state. The end of the protrusion 61 toward the inner cavity of the expandable structure 21 has a smooth surface to reduce the risk of the protrusion 61 damaging the balloon 11.

[0067] The cutting unit 31 includes a base 313 along its width direction and a plurality of cutting teeth 314 protruding along the width direction of the base 313. Each cutting tooth 314 includes an inner surface 3141 and an outer surface 3142 along its thickness direction. When the expandable structure 21 is in a radially contracted state, the inner surface 3141 of the cutting tooth 314 is closer to the inner cavity of the expandable structure 21 than the outer surface 3142. Each cutting tooth 314 has a hemispherical protrusion 61 on its inner surface 3141. By providing the protrusion 61 on the tooth, the success rate of directional flipping can be greatly improved. In other embodiments, an elongated protrusion 61 can also be provided on the bottom edge of the tooth near the non-cutting edge 312. This elongated protrusion 61 extends from one axial end of the cutting unit 31 to the other axial end of the cutting unit 31 to further improve the success rate of directional flipping. In other embodiments, the protruding unit 60 may further include one or more protrusions 61 disposed on the second connecting unit 332, the protrusions 61 being closer in the width direction of the second connecting unit 332 to the side of the second connecting unit 332 adjacent to the cutting gap 34 (i.e., the third side 3321) to further improve the success rate of directional flipping.

[0068] Alternatively, in another embodiment, this embodiment can also achieve directional flipping by adjusting the length of the cutting gap 34 and the asymmetrical structure of the first connecting unit 331 and the second connecting unit 332.

[0069] For example, refer to Figure 3 When the expandable structure 21 is in a radially contracted state, the axial length L1 of the cutting gap 34 is less than the axial length L2 of the expandable gap 35. For example, the ratio between the axial length L2 of the expandable gap and the axial length L1 of the cutting gap 34 is in the range of 1.1 to 5. With this configuration, coupled with the low normal bending stiffness of the flexible rods 51 on both sides of the expandable gap, during the radial expansion of the expandable structure 21, the expandable gap 35 will expand before the cutting gap 34 in the gaps adjacent to the cutting unit 31. This causes the ends of the first connecting unit 331 and the second connecting unit 332 corresponding to the expandable gap 35 that are away from the connecting node 32 to expand in a direction away from each other.

[0070] The tangential bending stiffness of the connecting unit 33 is greater than its normal bending stiffness. Here, the tangential direction refers to the width direction of the connecting unit 33, and the normal direction refers to the thickness direction. For example, the tangential bending stiffness of the connecting unit 33 can be greater than its thickness to achieve this. For instance, the width-to-thickness ratio of the connecting unit 33 can be 1.2 to 10, such as 1.5 to 8, and different widths and thicknesses can be selected depending on the material. Because the tangential bending stiffness of the connecting unit 33 is greater than its normal bending stiffness, it is easier for the connecting unit 33 to deform in the normal direction during the radial expansion of the expandable structure 21, making it easier to flip. This, in turn, facilitates the flipping of the connected cutting unit 31 and connecting node 32.

[0071] Furthermore, in this embodiment, the tangential bending stiffness of the cutting unit 31 can be greater than the normal bending stiffness of the cutting unit 31. Here, the tangential direction of the cutting unit 31 refers to its width direction, and the normal direction refers to its thickness direction. For example, the tangential bending stiffness of the cutting unit 31 can be greater than its normal bending stiffness by making its width greater than its thickness. For instance, the width-to-thickness ratio of the cutting unit 31 can be 3 to 15, such as 4.5 to 10. Different widths and thicknesses can be selected depending on the material. The width of the cutting unit 31 can be greater than the width of the connecting portion 33. The greater tangential bending stiffness of the cutting unit 31 than its normal bending stiffness makes it easier for the cutting unit 31 to deform in the normal direction during the radial expansion of the expandable structure 21, thus making it easier for the cutting unit to flip.

[0072] In this embodiment, the tangential bending stiffness of the connecting node 32 can also be greater than the normal bending stiffness of the connecting node 32. The tangential direction of the connecting node 32 refers to its width direction (i.e., along the circumference of the expandable structure 21), and the normal direction of the connecting node 32 refers to its thickness direction (i.e., along the radial direction of the expandable structure 21). For example, the tangential bending stiffness of the connecting node 32 can be greater than its normal bending stiffness by making its width greater than its thickness. The width-to-thickness ratio of the connecting node 32 can be 3–15, such as 4.5–10. Different widths and thicknesses can be selected depending on the material. The width of the connecting node 32 can be greater than the width of the connecting portion 33. Having a greater tangential bending stiffness than normal bending stiffness makes the connecting node 32 easier to flip.

[0073] Reference Figure 4The first connecting unit 331 and the second connecting unit 332 connected to the cutting unit 31 have an asymmetrical structure. That is, the mechanical properties of the first connecting unit 331 and the second connecting unit 332 connected to the same cutting unit 31 are different. For example, the bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332. The bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332, which means that the tangential bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332, and / or, the normal bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332. Because the bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332, the second connecting unit 332 is more prone to deformation than the first connecting unit 331 during the radial expansion of the expandable structure 21. Consequently, at the cutting unit 31 connected to it, the second connecting unit 332 flips relative to the first connecting unit 331 in a direction further away from the inner cavity of the expandable structure 21. The second edge 322 of the connecting node 32 also flips relative to the first edge 321 in a direction further away from the inner cavity of the expandable structure 21. Furthermore, due to the first side 3 of the first connecting unit 331... The arrangement directions of the second side 311 and the second side 3312 in the circumferential direction of the expandable structure 21, the arrangement directions of the third side 3321 and the fourth side 3322 of the second connecting unit 332 in the circumferential direction of the expandable structure 21, the arrangement directions of the first edge 321 and the second edge 322 of the connecting node 32 in the circumferential direction of the expandable structure 21, and the arrangement directions of the non-cutting edge 312 and the cutting edge 311 of each cutting unit 31 in the circumferential direction of the expandable structure 21 are all the same. Therefore, the directional flipping of the connecting part 33 connected to the cutting unit 31 can cause the cutting unit 31 to directionally flip.

[0074] There are several ways to ensure that the bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332. For example, there may be at least one or more of the following differences between the first connecting unit 331 and the second connecting unit 332: the minimum width of the first connecting unit 331 is greater than or equal to the maximum width of the second connecting unit 332; the minimum width of the first connecting unit 331 is greater than the minimum width of the second connecting unit 332; the minimum thickness of the first connecting unit 331 is greater than or equal to the maximum thickness of the second connecting unit 332; the minimum thickness of the first connecting unit 331 is greater than the minimum thickness of the second connecting unit 332; and the elastic modulus of the first connecting unit 331 is greater than the elastic modulus of the second connecting unit 332.

[0075] For example, refer to Figures 3 to 5The first connecting unit 331 and the second connecting unit 332 are integrally cut from the same material. The thickness of the first connecting unit 331 is basically equal to the thickness of the second connecting unit 332. The minimum width of the first connecting unit 331 is greater than or equal to the maximum width of the second connecting unit 332. The minimum width of the first connecting unit 331 is greater than the minimum width of the second connecting unit 332. For example, the first connecting unit 331 and the second connecting unit 332 are both equal-width structures (e.g., equal-width rod-shaped structures). The width of the first connecting unit 331 is greater than the width of the second connecting unit 332. In other embodiments, the first connecting unit 331 has a constant width structure, while the second connecting unit 332 may have a non-constant width structure. For example, the second connecting unit 332 may include a tapering section, the width of which is less than the width of the axial end of the second connecting unit 332. The width of the second connecting unit 332 decreases and then increases from one axial end to the other. The maximum width of the second connecting unit 332 is less than or equal to the width of the first connecting unit 331, and the minimum width of the second connecting unit 332 is less than the width of the first connecting unit 331. In other embodiments, the second connecting unit 332 may have a constant width structure, while the first connecting unit 331 may have a non-constant width structure. The first connecting unit 331 may include a widening section, the width of which is greater than the width of other regions. The width of the second connecting unit 332 is less than the width of the widening section, and the width of the second connecting unit 332 is less than or equal to the minimum width of the first connecting unit 331. In other embodiments, both the first connecting unit 331 and the second connecting unit 332 are non-equal width structures, with the minimum width of the first connecting unit 331 being greater than or equal to the maximum width of the second connecting unit 332. It is understood that multiple tapering and widening sections can be provided, and they can be located in any region along the axial direction of the connecting portion 33. The tapering and widening sections can simultaneously be located on the same connecting portion 33. In other embodiments, the widths of the first connecting unit 331 and the second connecting unit 332 can be controlled in other ways so that the bending stiffness of the first connecting unit 331 is greater than that of the second connecting unit 332.

[0076] For example, in some embodiments, the first connecting unit 331 and the second connecting unit 332 are integrally cut from the same material. The width of the first connecting unit 331 is substantially equal to the width of the second connecting unit 332. The minimum thickness of the first connecting unit 331 is greater than or equal to the maximum thickness of the second connecting unit 332. The minimum thickness of the first connecting unit 331 is greater than the minimum thickness of the second connecting unit 332. For example, both the first connecting unit 331 and the second connecting unit 332 are of equal thickness (e.g., rod-like structures of equal thickness), and the thickness of the first connecting unit 331 is greater than the thickness of the second connecting unit 332. In other embodiments, the first connecting unit 331 is of equal thickness, and the second connecting unit 332 may be of non-equal thickness. The second connecting unit 332 includes a reduced-thickness section, the thickness of which is less than the thickness of the axial end of the second connecting unit 332. The maximum thickness of the second connecting unit 332 is less than or equal to the thickness of the first connecting unit 331, and the minimum thickness of the second connecting unit 332 is less than the thickness of the first connecting unit 331. In other embodiments, the second connecting unit 332 may be a uniform thickness structure, while the first connecting unit 331 may be a non-uniform thickness structure. The first connecting unit 331 includes a thickened section, which is thicker than other areas. The thickness of the second connecting unit 332 is less than the thickness of the thickened section, and the thickness of the second connecting unit 332 is less than or equal to the minimum thickness of the first connecting unit 331. In other embodiments, both the first connecting unit 331 and the second connecting unit 332 are non-uniform thickness structures, and the minimum thickness of the first connecting unit 331 is greater than or equal to the maximum thickness of the second connecting unit 332. It is understood that multiple thickening and reducing sections and thickening sections may be provided, and they may be located in any region along the axial direction of the connecting portion 33. The thickening and reducing sections and thickening sections may simultaneously be located on the same connecting portion 33. In other embodiments, the thicknesses of the first connecting unit 331 and the second connecting unit 332 may be controlled in other ways so that the bending stiffness of the first connecting unit 331 is greater than the bending stiffness of the second connecting unit 332.

[0077] For example, in some embodiments, the bending stiffness of the first connecting unit 331 can be greater than that of the second connecting unit 332 by making the elastic modulus of the first connecting unit 331 greater than that of the second connecting unit 332. For example, the first connecting unit 331 and the second connecting unit 332 are made of different materials, and the elastic modulus of the material of the first connecting unit 331 is greater than that of the material of the second connecting unit 332.

[0078] In other embodiments, the bending stiffness of the first connecting unit 331 can be made greater than that of the second connecting unit 332 by providing a reinforcing member on the first connecting unit 331, or by performing local weakening treatment on the second connecting unit 332, for example, by drilling holes or providing notches at local locations in the second connecting unit 332. It is understood that in other embodiments, the bending stiffness of the first connecting unit 331 can also be made greater than that of the second connecting unit 332 by any other suitable method.

[0079] Understandably, this embodiment can also be modified by providing a protruding unit 60 (see reference). Figure 6 Oriented flipping can be achieved by adjusting the length of the cutting gap 34 and one or more of the asymmetrical structures of the first connecting unit 331 and the second connecting unit 332. When the protruding unit 60 is set and the two methods of adjusting the length of the cutting gap 34 and the asymmetrical structures of the first connecting unit 331 and the second connecting unit 332 are used in combination, the success rate of oriented flipping can be improved to a greater extent.

[0080] Figure 2 and Figure 3 The cutting units 31 in the device are all straight, elongated sheet-like structures. The non-cutting edges 312 of the straight cutting units 31 are straight, thus providing better stability during the flipping process. In other embodiments, the cutting units 31 can also be bent circumferentially along the expandable structure 21 to form wavy, arc-shaped, or other axially expandable sheet-like structures, in order to further improve the bending adaptability of the cutting device 20 and reduce the probability of the cutting units 31 warping.

[0081] In this embodiment, refer to Figure 3 , Figure 4Both axial ends of the first gap 341 are connected to a second gap 342. When the expandable structure 21 is in a radially contracted state, the width of the first gap 341 adjacent to the cutting edge 311 of the cutting unit 31 is approximately equal to the width of the second gap 342 connected to the first gap 341. In other embodiments, the minimum width of the first gap 341 adjacent to the cutting edge 311 can be appropriately increased to reduce the risk of the cutting edge 311 damaging the balloon 11 due to the reduction in the width of the first gap 341 during the radial contraction of the expandable structure 21. For example, when the expandable structure 21 is in a radially contracted state, the minimum width of the first gap 341 adjacent to the cutting edge 311 of the cutting unit 31 is greater than the maximum width of the second gap 342 connected to the first gap 341. When the expandable structure 21 is in a radially contracted state, the minimum width of the first gap 341 adjacent to the cutting edge 311 of the cutting unit 31 can also be greater than the maximum width of other gaps in the expandable structure 21. For example, the two ends of the first gap 341 are respectively connected to two second gaps 342. When the expandable structure 21 is in a radially contracted state, the minimum width of the first gap 341 adjacent to the cutting edge 311 of the cutting unit 31 is greater than the sum of the maximum widths of the two second gaps 342 connected to one end of the first gap 341 in the axial direction. For example, the minimum width of the first gap 341 adjacent to the cutting edge 311 of the cutting unit 31 is approximately equal to the sum of the maximum widths of the two second gaps 342 connected to one end of the first gap 341 in the axial direction, the first connecting unit 331, and the second connecting unit 332.

[0082] Reference Figure 1 , Figure 7In this embodiment, the cutting device 20 further includes a first end 22 disposed at the distal end of the expandable structure 21 and a conduit 23 disposed at the proximal end of the expandable structure 21. The lumens of the first end 22, the expandable structure 21, and the conduit 23 are interconnected. The first end 22 has openings at both its proximal and distal ends, and the outer diameter of the proximal end of the first end 22 is larger than the outer diameter of its distal end. The proximal end of the first end 22 can be fitted onto the distal end of the expandable structure 21 and fixed together. The proximal end of the expandable structure 21 is further provided with an end connector 40, which connects to the distal end of the conduit 23. The end connector 40 is a radially expandable structure. For example, the end connector 40 includes a first connector 41 and a second connector 42. The first connector 41 includes multiple connecting rods 411 arranged circumferentially along the expandable structure 21 at intervals. The second connector 42 includes two waverings arranged sequentially along the axial direction, namely a first wavering 421 and a second wavering 422. Each wavering extends radially along the expandable structure 21. The structure 21 is radially arranged and consists of closed annular structures. Each wave loop includes multiple proximal vertices 43, multiple distal vertices 44, and wave rods 45 connecting adjacent proximal vertices 43 and distal vertices 44. The first wave loop 421 and the second wave loop 422 are out of phase. The proximal vertices 43 of the first wave loop 421 and the distal vertices 44 of the second wave loop 422 are axially opposite and fixedly connected. The distal vertices 44 of the first wave loop 421 correspond one-to-one with the connecting rods 411 of the first connecting member 41 and are fixedly connected to each other. In other embodiments, one of the first connecting member 41 and the second connecting member 42 may be omitted. The number of connecting rods 411 in the first connecting member 41 can be set as needed, and the connecting rods 411 do not necessarily correspond one-to-one with the distal vertices 44 of the first wave loop 421. In other embodiments, the number of wave loops in the end connector 40 may be one or more than two. When there are multiple wave loops, the phases between two adjacent wave loops may be different, and the wave loops may also be connected to each other in other ways. In other embodiments, the wave loops in the end connector 40 may be non-closed structures. In other embodiments, the first connector 41 and the second connector 42 may be replaced by other mesh structures, spiral structures, etc., as long as the end connector 40 can be radially expandable. Before being connected to the conduit 23, the diameter of the proximal end of the end connector 40 is smaller than the diameter of the distal end of the conduit 23 in its natural state. Since the end connector 40 is a radially expandable structure, when connecting it to the conduit 23, the proximal end of the end connector 40 is sleeved over the distal end of the conduit 23 to make an interference fit between the two, thereby achieving a stable connection between the expandable structure 21 and the conduit 23. Then, the connecting sleeve 24 is sleeved over the end connector 40, and the connecting sleeve 24, the end connector 40 and the conduit 23 are connected to each other by heat fusion, which can further improve the firmness of the connection between the expandable structure 21 and the conduit 23.The aforementioned conduit 23 and connecting sleeve 24 can be made of the same or different materials. For example, the materials of the conduit 23 and the connecting sleeve can be selected from one or more of polymer materials such as PEBAX (polyether block polyamide), nylon, PEEK (polyether ether ketone), PTFE (polytetrafluoroethylene), and PI (polyimide) or other materials. In other embodiments, the expandable structure 21 and the conduit 23 can be connected by other methods such as bonding, and the aforementioned connecting sleeve 24 can be omitted. In this embodiment, the distal end of the aforementioned expandable structure 21 can also be provided with an end connector 40 connected to the first end 22, and the distal end connector 40 is mirror-symmetrical to the proximal end connector 40.

[0083] Reference Figure 1 , Figure 8 The balloon catheter 10 may include a second end 13, a balloon 11, and a tubular assembly 12. The distal end of the balloon 11 is connected to the second end 13. The proximal outer diameter of the second end 13 is larger than the distal outer diameter of the second end 13, and the distal outer diameter of the second end 13 may be smaller than the distal inner diameter of the first end 22, thereby facilitating the confinement of the balloon catheter 10 within the lumen of the cutting device 20. In other embodiments, the dimensions of the first end 22 and the second end 13 may be set according to actual needs.

[0084] Reference Figure 8 When the balloon 11 is inflated, it includes a proximal segment 111, a distal segment 113, and an intermediate segment 112 connecting the proximal segment 111 and the distal segment 113 at both ends. In this embodiment, the cross-sectional shape of the balloon 11 is approximately circular. In other embodiments, the cross-section of the balloon 11 can also be elliptical, crescent-shaped, semi-circular, or any other suitable shape. The proximal segment 111 and the distal segment 113 are approximately conical, and the intermediate segment 112 is approximately cylindrical. The cross-sectional area of ​​the proximal end of the proximal segment 111 is smaller than that of the distal end, the cross-sectional areas of the intermediate segment 112 are approximately equal, and the cross-sectional area of ​​the proximal end of the distal segment 113 is larger than that of the distal end. In other embodiments, the balloon 11 can be any suitable shape. The balloon 11 can be a semi-compliant balloon 11 or a non-compliant balloon 11, and can be made of one or more of the following materials: polyethylene, polyurethane, nylon and polyethylene terephthalate.

[0085] The tubular assembly 12 includes at least one tubular member. For example, the tubular assembly 12 includes two tubular members: an inner tube 121 and an outer tube 122. The inner tube 121 passes through the outer tube 122 and axially penetrates the inner lumen of the balloon 11, and is fixedly connected to the distal end of the balloon 11. The distal end of the outer tube 122 is fixedly connected to the proximal end of the balloon 11. A delivery channel is formed between the inner tube 121 and the outer tube 122, which communicates with the inner lumen of the balloon 11. Media can be injected into or withdrawn from the inner lumen of the balloon 11 through this delivery channel. The inner tube 121 also has a guidewire channel, through which a guidewire can axially pass. The material of the tubular member can be selected from one or more of polymeric materials such as PEBAX (polyether block polyamide), nylon, PEEK (polyether ether ketone), PTFE (polytetrafluoroethylene), and PI (polyimide), or other materials.

[0086] In actual use, the cutting system 100 of this embodiment can be pre-installed outside the balloon catheter 10 outside the body, and then the assembled cutting device 20 and balloon catheter 10 can be delivered to the target location (e.g., a narrowed blood vessel) inside the body through a delivery device. By controlling the radial expansion of the balloon 11, the expandable structure 21 of the cutting device 20 is driven to expand radially. The cutting unit 31 in the cutting device 20 flips and contacts the target location to achieve cutting. After the treatment is completed, the balloon 11 is controlled to contract radially, and the expandable structure 21 also contracts radially. Finally, the cutting device 20 and balloon catheter 10 are removed from the body. Understandably, in other embodiments, the cutting device 20 and the balloon catheter 10 may also be assembled after entering the body. For example, the cutting device 20 may be delivered to the target location first via a delivery device, and then the balloon catheter 10 may be guided to the target location, with the balloon 11 inserted into the lumen of the expandable structure 21; or, the balloon catheter 10 may be delivered to the target location first via a delivery device, and then the cutting device 20 may be guided to the target location, with the expandable structure 21 fitted over the balloon 11.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A cutting device, characterized in that, include: An expandable structure having a radially expanded state and a radially contracted state is used to be fitted over the balloon of a balloon catheter; the expandable structure includes a cutting portion and a flexible portion along the axial direction, and the flexible portion is connected to the axial end of the cutting portion.

2. The cutting device according to claim 1, characterized in that, The cutting section includes a plurality of cutting units spaced apart circumferentially along the expandable structure, and the flexible section includes a plurality of flexible rods spaced apart circumferentially along the expandable structure. Both the flexible rods and the cutting units extend axially along the expandable structure.

3. The cutting device according to claim 2, characterized in that, The normal bending stiffness of the flexible rod is less than that of the cutting unit.

4. The cutting device according to claim 2, characterized in that, The flexible rod and the cutting unit are made of the same material, the thickness of the flexible rod is less than or equal to the thickness of the cutting unit, and the cross-sectional area of ​​the flexible rod is less than the cross-sectional area of ​​the cutting unit.

5. The cutting device according to claim 2, characterized in that, The elastic modulus of the flexible rod is less than that of the cutting unit, the thickness of the flexible rod is less than or equal to the thickness of the cutting unit, and the cross-sectional area of ​​the flexible rod is less than or equal to that of the cutting unit.

6. The cutting device according to claim 2, characterized in that, The ratio of the minimum width of the cutting unit to the maximum width of the flexible rod ranges from 1.2 to 5, and the ratio of the length of the flexible rod to the length of the cutting unit ranges from 0.5 to 2.

7. The cutting device according to claim 2, characterized in that, The flexible rod is a straight rod, and the maximum gap width between two circumferentially adjacent flexible rods is greater than the maximum gap width between two circumferentially adjacent cutting units.

8. The cutting device according to claim 2, characterized in that, Each of the cutting units includes a cutting edge and a non-cutting edge; when the expandable structure is in a radially contracted state, the cutting edge and the non-cutting edge are arranged circumferentially along the expandable structure, and when the expandable structure is in a radially expanded state, the cutting edge is further away from the inner cavity of the expandable structure relative to the non-cutting edge.

9. The cutting device according to claim 8, characterized in that, The inner wall of the cutting unit is provided with a protruding unit. When the expandable structure is in a radially contracted state, the protruding unit protrudes towards a direction closer to the inner cavity of the expandable structure compared to other areas of the expandable structure. Along the width direction of the cutting unit, the protruding unit is closer to the cutting edge of the cutting unit and further away from the non-cutting edge of the cutting unit.

10. A cutting system, characterized in that, It includes a balloon catheter and a cutting device as described in any one of claims 1 to 9, wherein the cutting device is detachably sleeved on the outside of the balloon catheter.

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