A stent introduction device and its application

Abstract

The present invention provides a stent introduction device and its application, which relates to the technical field of medical devices. It includes a sheath tube and a sheath tube seat. The sheath tube seat is fixedly installed at the proximal end of the sheath tube. The sheath tube includes an inner layer and an outer layer. The outer layer wraps around the surface of the inner layer. The distal end of the inner layer extends out of the distal end of the outer layer by a first length. The friction coefficient and hardness of the inner layer are both lower than those of the outer layer. The introduction sheath tube of the present invention adopts a single-lumen double-layer structure. Its outer layer is made of a hard material and has good stability. The inner layer is made of a softer material and slightly extends out of the outer layer. When loading a drug-eluting stent, it can effectively avoid the inward wrinkling and warping of the edge of the inner layer. At the same time, the extended part serves as a new head end, and its material is soft, which can effectively solve the problem of scratching of the drug coating by the hard outer layer and play a role in protecting the drug coating.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and particularly relates to a stent introduction device and its application. Background Art

[0002] Intracranial atherosclerotic stenosis is a neurovascular disease, which is characterized by the accumulation of plaques on the inner wall of intracranial arteries, leading to vascular stenosis. This condition greatly increases the risk of patients suffering from transient ischemic attack (TIA) or stroke. In interventional therapy, significant developments have been made in the methods for treating intracranial atherosclerotic stenosis. Initially, bare metal stents (BMS) were used to mechanically dilate the stenotic arteries and reconstruct the blood flow pathway. Although such stents are effective in restoring vascular patency, they cannot solve the problem of restenosis because they may trigger the hyperplasia of vascular endothelium, thus causing new stenosis. To overcome this limitation, drug-eluting stents (DES) emerged. These stents gradually release drugs while dilating the blood vessels to inhibit the excessive hyperplasia of vascular endothelium, thereby reducing the risk of restenosis. Drug-eluting stents have thus become the preferred method for treating intracranial atherosclerotic stenosis, providing better long-term efficacy.

[0003] In clinical applications, with the widespread use of drug-eluting stents, the technical requirements for the introduction devices have also increased. These stents need to be compressed and loaded into the main body of the introduction device before use. It should be emphasized that these introduction devices do not directly enter the vascular system. Before the implantation surgery of the drug-eluting stent begins, the stent must be safely transferred from the introduction device to the microcatheter. During the loading and transfer processes, the stiffness of the head end of the introduction device is crucial. During the loading stage, the head end of the introduction device should be flexible to gently protect the drug coating and avoid damaging it during loading. During the transfer stage, the head end needs to have a certain hardness to ensure smooth docking with the microcatheter.

[0004] The loading process of the stent is very important, aiming to reduce the outer diameter of the stent to make it easier to be transported to the target site. In this process, a small section of the stent is first cooled at a low temperature to remove its superelasticity. Then the cooled part is tightly compressed under the action of mechanical equipment, and its outer diameter size is significantly reduced. At this time, the end of the stent will slightly protrude, facilitating the smooth swallowing of the introduction device. The protruding end itself has radial support force. Since there is no restraint of mechanical equipment, such as Figure 1As shown, it will appear to be in a petal-like open state. Subsequently, the exposed part is sent into the introduction device through the head end, and the cooling-compression-feeding process is repeated until the stent is completely loaded, that is, the loading process is completed. After loading, the stent will be carefully inspected to confirm whether its drug coating is damaged or detached. During the interventional procedure, the introduction device loaded with the stent is first accurately docked with the microcatheter. Subsequently, the stent will be slowly and carefully transferred from the introduction device to the microcatheter. This process requires meticulous operation to ensure the integrity of the stent drug coating. Next, the stent is introduced into the patient's blood vessel through the microcatheter and finally accurately placed in the predetermined position to complete the stent implantation.

[0005] The introduction device is usually a hollow double-layer structure, in which the outer layer is made of hard material to provide stability, and the inner layer is made of low-friction material to reduce the push resistance. The overall design is intended to reduce the difficulty of operation during surgery and improve the smoothness and stability of stent push. In conventional designs, both the inner and outer layers use flush and equal-length incisions at the head end. This design performs well during the transfer process. However, during the loading process, when the stent is delivered through the head end, the inner layer of the introduction device may be scraped by the open end of the stent, causing the edge of the inner layer to wrinkle and warp inward, thereby exposing the hard outer layer. In the subsequent loading and delivery process, due to the self-elasticity of the nickel-titanium alloy stent, the stent crest will have an outward supporting force during assembly, which will collide and scratch with the hard head end material, thereby damaging the drug coating and causing the drug coating to break or even fall off. When the stent enters the introduction device, the stent rod will be constrained by the introduction device at this time, and it is straight in the introduction device, so the crest will not collide with the hard outer layer.

[0006] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0007] The object of the present invention is to provide a stent introduction device which can effectively prevent the inner layer edge from wrinkling and warping inwards, so as to solve the problem that the drug coating is easily scratched and damaged when the drug-coated stent is loaded.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A stent introduction device includes a sheath and a sheath seat, wherein the sheath seat is fixedly installed at the proximal end of the sheath, the sheath includes an inner layer and an outer layer, the outer layer is wrapped around the surface of the inner layer, the distal end of the inner layer extends a first length from the distal end of the outer layer, and the friction coefficient and hardness of the inner layer are both lower than those of the outer layer.

[0010] Preferably, a buffer layer is provided at the junction of the inner layer and the outer layer at the distal end, and the buffer layer covers the distal end of the outer layer.

[0011] Preferably, the buffer layer extends a second length in the proximal direction of the outer layer.

[0012] Preferably, the buffer layer extends a third length in the distal direction of the inner layer, and the third length is not greater than the first length.

[0013] Preferably, the thickness of the part of the buffer layer located on the surface of the inner layer gradually changes in the distal direction.

[0014] Preferably, the thickness of the part of the buffer layer located on the surface of the inner layer gradually decreases in the distal direction.

[0015] Preferably, the sheath is hollow, and the outer diameter of the sheath gradually decreases from the proximal end to the distal end.

[0016] Preferably, a cutting mark is provided at the distal end of the sheath near the buffer layer.

[0017] Preferably, the material of the outer layer is selected from one of PA, PEEK, PI, PPS, and POM.

[0018] Preferably, the material of the inner layer is PTFE or TPU.

[0019] Preferably, the material of the buffer layer is Pebax.

[0020] Preferably, the sheath and the sheath seat are integrally formed by injection molding.

[0021] The present invention also provides an application of any one of the above stent introduction devices. Specifically, it is used to load a drug-eluting stent. After the drug-eluting stent is loaded, the inner layer and the outer layer of the sheath are cut flush along the cutting mark.

[0022] Advantageous effects:

[0023] (1) In the present invention, the introduction sheath adopts a single-chamber double-layer structure. Its outer layer is made of a hard material to ensure stability. The inner layer material of the introduction device sheath is softer and slightly extends out of the outer layer. Such a design can effectively avoid the inward wrinkling and warping of the inner layer edge when loading the drug stent. At the same time, as the new head end, its material is soft, which can solve the problem of scratching the drug coating by the hard outer layer and play a role in protecting the drug coating.

[0024] (2) Pebax material is used as the buffer layer, providing moderate hardness and good elasticity to promote a smoother transition. After loading is completed, these Pebax elastic parts and the extended inner layer that are specially designed for loading will be completely removed after the stent is successfully loaded to obtain a harder head end, which ensures the smooth progress of the stent transfer process.

[0025] (3) The stent introduction device designed by the present invention consists of an integrated seat and a sheath tube. These two components are integrally formed by precision injection molding technology, forming a sealed and strong connection structure to ensure the integrity of the instrument;

[0026] (4) After loading the drug-eluting stent, the stent introduction device provided by the present invention can cut off the part of the distal end of the inner tube protruding from the outer tube, making the distal ends of the inner tube and the outer tube neatly cut, which can avoid the bending of the protruding part of the relatively soft inner tube during subsequent packaging and transportation, and prevent the deformation of the inner hole from affecting the passage of the drug-eluting stent. Description of the Drawings

[0027] The schematic drawings of the specification forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them:

[0028] Figure 1 It is a schematic diagram showing the stent in a petal-like opening when the existing stent introduction device introduces the stent.

[0029] Figure 2 It is a front view structural diagram of a stent introduction device provided by Embodiment 1 of the present invention.

[0030] Figure 3 It is a front view structural diagram of a stent introduction device provided by Embodiment 2 of the present invention.

[0031] Figure 4 It is Figure 3 The enlarged view at A in

[0032] Figure 5 It is a schematic diagram showing the buffer layer extending to the distal end of the inner layer in the embodiment of the present invention.

[0033] Figure 6 It is a schematic diagram showing the buffer layer extending to the proximal end of the outer layer in the embodiment of the present invention.

[0034] Figure 7 It is a schematic diagram after truncating the stent introduction device provided by the embodiment of the present invention.

[0035] Figure 8 It is Figure 7 The enlarged view at B in

[0036] In the figure: 100, sheath tube; 200, sheath tube seat; 101, inner layer; 102, outer layer; 103, buffer layer. Detailed Embodiments

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention fall within the protection scope of the present invention.

[0038] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0039] In the description of the present invention, the meaning of several is one or more, the meaning of multiple is two or more, greater than, less than, exceeding, etc. are understood as not including the recited number, and above, below, within, etc. are understood as including the recited number. If there is a description of first and second, it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0040] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, it may be a fixed connection or a movable connection, or a detachable connection or a non-detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two elements, indirect communication or the interaction relationship between two elements.

[0042] In the present invention, "proximal end" refers to the end close to the operator, and "distal end" refers to the end far from the operator. Without special instructions, the left end in the attached drawings of the specification of the present invention is the "proximal end", and the right end is the distal end.

[0043] Description of English abbreviations:

[0044] PA, the full name is Polyamide, Chinese name is polyamide, commonly known as nylon;

[0045] PEEK, the full name is poly(ether-ether-ketone), Chinese name is polyetheretherketone;

[0046] PI, whose full name is Polyimide, is called polyimide in Chinese;

[0047] PPS, whose full name is Polyphenylene sulfide, is called polyphenylene sulfide in Chinese;

[0048] POM, whose full name is polyformaldehyde, is called polyoxymethylene in Chinese;

[0049] TPU, whose full name is Thermoplastic Polyurethane, is called thermoplastic polyurethane in Chinese;

[0050] Pebax, whose full name is Polyether Block Amide, is called polyether block amide in Chinese.

[0051] The present invention will be described in detail below in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0052] In view of the problem that the current introduction device for drug coatings is prone to coating scratching and peeling during the stent loading process, the present invention provides a stent introduction device, as Figure 2 , 3 shown. The stent introduction device includes a sheath 100 and a sheath base 200. The sheath base 200 is fixedly installed at the proximal end of the sheath 100. The sheath 100 includes an inner layer 101 and an outer layer 102. The outer layer 102 wraps around the surface of the inner layer 101. The distal end of the inner layer 101 extends out of the distal end of the outer layer 102 by a first length D1. The friction coefficient and hardness of the inner layer 101 are both lower than those of the outer layer 102. Due to the lack of the wrapping of the outer layer 102, the distal end of the sheath 100 has a lower hardness within the extending length range of the inner layer 101. When loading a drug-eluting stent, it can effectively avoid the inward wrinkling and warping of the edge of the inner layer 101. At the same time, as a new tip, its material is soft, which can solve the problem of scratching the drug coating by the hard outer layer 102 and play a role in protecting the drug coating.

[0053] In the present invention, the first length D1 is 0.1 - 5 mm (for example, 0.11 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.9 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0 mm, 4.9 mm).

[0054] The stent introduction device designed by the present invention is composed of a sheath base 200 and a sheath 100. These two components are integrally formed by precision injection molding technology, forming a sealed and firm connection to ensure the integrity of the instrument.

[0055] The sheath tube 100 in the present invention adopts a single - cavity double - layer structure. Its outer layer 102 is made of a hard material to ensure stability, while the inner layer 101 is made of a material with a low coefficient of friction and softness. The purpose is to reduce the resistance during propulsion and at the same time protect the drug coating on the stent from damage. When designing the head end of the introducing device, the inner layer 101 material slightly extends beyond the outer layer 102, and the inner and outer layer 102 polymer tubes with different materials and hardnesses are closely stacked and fused. In this way, when loading the drug - eluting stent through the head end, the extended inner layer 101 can not only prevent the inner layer 101 edge from wrinkling and warping inward due to the scraping of the opened end of the stent during the loading process, but also, as the new head end, its soft material can effectively isolate the direct contact between the drug coating and the hard material of the outer layer 102, thereby protecting the drug coating from scraping damage. It can be seen that the extended inner layer 101 can effectively prevent the drug coating from being scratched by the hard material of the outer layer 102 and protect the drug coating.

[0056] In the present invention, the material of the outer layer 102 is selected from any one of PA, PEEK, PI, PPS, and POM. Its hardness ranges from 70 to 95 HD (such as 71 HD, 75 HD, 79 HD, 80 HD, 81 HD, 85 HD, 89 HD, 90 HD, 94 HD), and the dynamic friction coefficient is 0.1 to 0.5 (such as 0.11, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.49), as shown in Table 1 below:

[0057] Table 1 Material types, hardness, and dynamic friction coefficient of the outer layer 102

[0058]

[0059] In a preferred embodiment of the present invention, the material of the outer layer 102 is selected from PA. Its hardness range is preferably 70 to 80 HD (such as 71 HD, 72 HD, 73 HD, 74 HD, 75 HD, 76 HD, 77 HD, 78 HD, 79 HD), and the dynamic friction coefficient is preferably 0.2 to 0.4 (0.21, 0.23, 0.25, 0.27, 0.29, 0.30, 0.31, 0.33, 0.35, 0.37, 0.39).

[0060] In one embodiment of the present invention, the material of the inner layer 101 is PTFE, with a hardness ranging from 50 to 60 HD (such as 51 HD, 52 HD, 53 HD, 54 HD, 55 HD, 56 HD, 57 HD, 58 HD, 59 HD), and a dynamic friction coefficient of 0.05 - 0.2 (such as 0.06, 0.08, 0.10, 0.12, 0.14, 0.15, 0.16, 0.18, 0.20). In another embodiment of the present invention, the material of the inner layer 101 is TPU, with a hardness ranging from 30 to 55 HD (such as 31 HD, 35 HD, 39 HD, 40 HD, 41 HD, 43 HD, 46 HD, 50 HD, 55 HD), and a dynamic friction coefficient of 0.05 - 0.2 (such as 0.06, 0.08, 0.10, 0.12, 0.14, 0.15, 0.16, 0.18, 0.20).

[0061] However, at the head end portion, the hardness difference between the two materials of the inner and outer layers 102 is significant, and the hardness changes suddenly in the transition region, which easily causes the inner layer 101 to bend in this region, making it difficult to load the stent. To solve this problem, in a preferred embodiment of the present invention, a buffer layer 103 made of Pebax is provided at the junction of the distal ends of the inner layer 101 and the outer layer 102. The thickness of the portion of the buffer layer 103 located on the surface of the inner layer 101 gradually changes in the distal direction. More specifically, the thickness of the portion of the buffer layer 103 located on the surface of the inner layer 101 gradually decreases in the distal direction, covering the distal end of the outer layer 102 with the buffer layer 103, thereby playing a transitional role. In some embodiments, other materials with similar properties can also be used instead of Pebax.

[0062] The Pebax material not only has a moderate hardness but also has good elasticity. By introducing the Pebax material as the buffer layer 103, a smoother transition is effectively achieved. During crimping, it can effectively prevent the coating from being damaged, and while protecting the drug coating, it makes the loading process more convenient, greatly improving the loading efficiency.

[0063] In the present invention, the Pebax material used for the buffer layer 103 can use products of the following grades:

[0064] 3533SA, with a hardness of 50 HD;

[0065] And 2533SA, 3533SA, 4033SA, 4533SA, 5533SA, 6333SA, 7033SA, 7233SA, and the hardness of these Pebax materials ranges from 25 to 72 HD.

[0066] In a preferred embodiment of the present invention, the buffer layer 103 extends in the proximal direction of the outer layer 102 by a second length, so that the buffer layer 103 completely covers the distal junction of the inner layer 101 and the outer layer 102, thereby making the structure at the junction smoother.

[0067] In a preferred embodiment of the present invention, the buffer layer 103 extends in the distal direction of the inner layer 101 by a third length, and the third length is not greater than the first length. For example, as Figure 4 shown, the third length is equal to the first length, so that the buffer layer 103 covers the entire head end of the inner layer 101; alternatively, the third length is less than the first length, so that a part of the head end of the inner layer 101 is not covered by the buffer layer 103.

[0068] The soft head end is extremely easy to bend during subsequent packaging and transportation, which will cause the inner hole to deform and make it difficult for the stent to pass through. In addition, when transferring the stent, the head end must be completely inserted into the microcatheter, which requires the head end to have sufficient hardness to ensure that the head end can smoothly and accurately dock with the microcatheter, thereby ensuring the smooth progress of the entire transfer process. To solve the above problems, as Figure 4 shown, these Pebax elastic parts and the extended inner layer 101 that are specially designed for loading optimization will be completely removed after the stent is successfully loaded, ensuring that the inner and outer layers 102 are neatly cut and have the same length at the head end, and ensuring the smooth progress of the entire stent transfer process.

[0069] In a preferred embodiment of the present invention, the sheath 100 and the sheath base 200 are integrally formed by precision injection molding technology, forming a sealed and solid connection structure, ensuring the integrity of the instrument, making it have good strength and connection accuracy, and having better sealing performance than the split-type introduction device.

[0070] According to an embodiment of the present invention, refer to Figure 2, the stent delivery device includes a sheath 100 and a sheath hub 200. The sheath hub 200 has a lumen communicating with the sheath 100. The proximal end of the sheath hub 200 has a handle for convenient operation, and anti-slip patterns are provided on the handle. The outer diameter of the proximal end of the sheath hub 200 is greater than the outer diameter of the sheath 100. A transition step is likely to occur at the connection between the sheath hub 200 and the sheath 100. To prevent bending at this location, in some embodiments, a smooth transition section (not shown in the figure) is provided at the transition step. The sheath 100 includes an inner layer 101 and an outer layer 102. The outer layer 102 wraps around the surface of the inner layer 101, that is, the sleeving method is adopted. In some embodiments, there is no limit to the thickness of the inner layer 101 and the outer layer 102 of the sheath 100. The distal end of the inner layer 101 extends a first length from the distal end of the outer layer 102. That is, on the premise that the proximal ends of the inner layer 101 and the outer layer 102 of the sheath 100 are flush, the length of the inner layer 101 is greater than the length of the outer layer 102. The extra length of the inner layer 101 compared to the outer layer 102 is the first length, denoted as D1. In one embodiment, the coefficient of friction and hardness of the inner layer 101 are both lower than those of the outer layer 102.

[0071] According to an embodiment of the present invention, refer to Figure 3 , a buffer layer 103 is provided at the distal junction of the inner layer 101 and the outer layer 102. The buffer layer 103 is made of a material with a hardness between that of the inner layer 101 and the outer layer 102, preferably Pebax material. In one embodiment, the buffer layer 103 covers the distal end of the outer layer 102. Refer to Figure 5 , the buffer layer 103 extends a second length in the proximal direction of the outer layer 102. The second length is the axial length of the buffer layer 103 covering the outer layer 102 of the sheath 100, denoted as D2. The second length is denoted as D2. The buffer layer 103 covering the outer layer 102 of the sheath 100 is beneficial for fixing the buffer layer 103 to the outer layer 102 and providing a supporting force to the buffer layer 103 to resist the force of the inner layer 101 from bending.

[0072] According to an embodiment of the present invention, refer to Figures 3 to 5 . The buffer layer 103 extends a third length in the distal direction of the inner layer 101. The third length is the axial length of the buffer layer 103 covering the inner layer 101 of the sheath 100, denoted as D3. The third length is not greater than the first length, that is, D3≤D1. In one embodiment, the first length is equal to the third length. In another embodiment, the third length is half of the first length.

[0073] According to an embodiment of the present invention, the thickness of the portion of the buffer layer 103 located on the surface of the inner layer 101 gradually changes in the distal direction. In one embodiment, the thickness of the portion of the buffer layer 103 located on the surface of the inner layer 101 gradually decreases in the distal direction. In one embodiment, the way of gradual change can be a proportional linear gradual change, a sine function gradual change, or a gradual change that is concave first and then convex. The specific way of gradual change is not limited. As long as the distal end of the buffer layer 103 closely adheres to the outer wall of the inner layer 101 to ensure the transition effect.

[0074] According to an embodiment of the present invention, at the distal end of the outer layer 102 of the sheath 100 near the buffer layer 103, a cutting mark is provided. The cutting mark can be a marked line drawn on the sheath 100 or a notch engraved on the sheath 100; in one embodiment, the cutting mark can be a transition line formed by the buffer layer 103 at its proximal end on the outer surface of the sheath 100 by self-heating; after the stent is successfully loaded in the introducing device of the present invention, it is cut along the marked line as needed to trim the head end of the sheath 100 flush for subsequent introduction operations.

[0075] A stent introducing device provided by the present invention, when used for loading a drug-eluting stent, after loading, the protruding portion of the inner layer 101 can be cut off, so that the distal ends of the inner layer 101 and the outer layer 102 are aligned and have the same length. The cutting position can be either the distal junction of the inner layer 101 and the outer layer 102, that is, the distal end face of the outer layer 102. If the lengths of the inner layer 101 and the outer layer 102 are sufficient, the inner layer 101 and the outer layer 102 can also be cut simultaneously at the proximal end of this end face.

[0076] After loading the drug-eluting stent, to facilitate subsequent introduction of the drug-eluting stent into the microcatheter, the outer diameter of the outer layer 102 in the embodiment of the present invention can adopt a variable diameter structure, so that the outer diameter of the outer layer 102 gradually decreases in the distal direction, so that the distal end of the stent introducing device can be more easily inserted into the microcatheter, thus facilitating subsequent introduction of the drug-eluting stent into the microcatheter.

[0077] The present invention provides the following specific embodiments to elaborate in detail on a stent introducing device of the present invention through these specific embodiments.

[0078] Embodiment 1

[0079] As Figure 2 shown, this embodiment provides a stent introducing device, including a sheath 100 and a sheath base 200. The sheath base 200 is fixedly installed at the proximal end of the sheath 100. The sheath 100 includes an inner layer 101 and an outer layer 102. The outer layer 102 wraps around the surface of the inner layer 101. The distal end of the inner layer 101 extends from the distal end of the outer layer 102 by a first length, and the first length is 2.0 mm.

[0080] In this embodiment, the outer layer 102 is made of PA material, with a hardness of 80 HD and a dynamic friction coefficient of 0.25. The inner layer 101 is made of PTFE material, with a hardness of 55 HD and a dynamic friction coefficient of 0.16, ensuring that both the friction coefficient and hardness of the inner layer 101 are lower than those of the outer layer 102.

[0081] By adopting the above settings, when loading the drug-eluting stent via the head end, the extended inner layer 101 can not only prevent the edges of the inner layer 101 from wrinkling and warping inward due to scraping during the loading process caused by the opening ends of the stent, but also, as the new head end, its soft material can effectively isolate the direct contact between the drug coating and the hard material of the outer layer 102, thereby protecting the drug coating from scraping damage.

[0082] After the loading of the drug-eluting stent is completed, the inner layer 101 is cut at the junction of the inner layer 101 and the outer layer 102 to completely remove the part of the inner layer 101 that protrudes from the outer layer 102, as Figure 7 、 8 shown. The distal ends of the cut inner layer 101 and the outer layer 102 are aligned and have the same length. After this treatment, it can be avoided that the protruding part of the inner layer 101 is bent under external force during subsequent packaging and transportation, preventing the deformed inner layer 101 from deforming, making it difficult for the drug-eluting stent to pass through. In addition, when transferring the drug-eluting stent, the head end of the stent introduction device must be completely inserted into the microcatheter. It is required that the head end has sufficient hardness to ensure that the head end can smoothly and accurately dock with the microcatheter, thus ensuring the smooth progress of the entire transfer process. Cutting off the protruding part of the inner layer 101 can well solve the problem of insufficient hardness of the head end during docking.

[0083] Embodiment 2

[0084] As Figure 3 shown, this embodiment provides a stent introduction device, including a sheath 100 and a sheath seat 200. The sheath seat 200 is fixedly installed at the proximal end of the sheath 100. The sheath 100 includes an inner layer 101 and an outer layer 102. The outer layer 102 wraps around the surface of the inner layer 101. The distal end of the inner layer 101 extends a first length from the distal end of the outer layer 102. The friction coefficient and hardness of the inner layer 101 are both lower than those of the outer layer 102.

[0085] In addition, as Figure 6 shown, a buffer layer 103 is provided at the distal junction of the inner layer 101 and the outer layer 102.

[0086] The buffer layer 103 covers the distal end of the outer layer 102 and extends a second length in the proximal direction of the outer layer 102. The buffer layer 103 extends a third length in the distal direction of the inner layer 101. The third length is less than the first length. The thickness of the part of the buffer layer 103 on the surface of the inner layer 101 gradually decreases in the distal direction.

[0087] The material of the buffer layer 103 is Pebax, which has a moderate hardness and good elasticity.

[0088] With the above settings, the buffer layer 103 covers the distal end of the outer layer 102, thus playing a transitional role, which can avoid the sudden change of hardness in the transitional area between the inner layer 101 and the outer layer 102, prevent the inner layer 101 from bending in this area, and make the stent easier to load.

[0089] Embodiment 3

[0090] This embodiment provides a stent introducer device, including a sheath 100 and a sheath hub 200. The sheath hub 200 is fixedly installed at the proximal end of the sheath 100. The sheath 100 includes an inner layer 101 and an outer layer 102. The outer layer 102 wraps around the surface of the inner layer 101. The distal end of the inner layer 101 extends a first length from the distal end of the outer layer 102. The friction coefficient and hardness of the inner layer 101 are both lower than those of the outer layer 102.

[0091] In addition, as Figure 5 shown, a buffer layer 103 is provided at the junction of the distal ends of the inner layer 101 and the outer layer 102. The material of the buffer layer 103 is Pebax, and the thickness of the part of the buffer layer 103 located on the surface of the inner layer 101 gradually decreases in the distal direction.

[0092] In this embodiment, the buffer layer 103 extends a third length in the distal direction of the inner layer 101. The third length is equal to the first length, so that the buffer layer 103 completely covers the part of the inner layer 101 extending out of the distal end of the outer layer 102. Compared with Embodiment 2, it can avoid the drastic change of the hardness of the extended part of the inner layer 101 at the junction of the buffer layer 103 and the inner layer 101.

[0093] In summary:

[0094] In the present invention, by making the inner layer of the sheath of the introducer device slightly extend out of the outer layer, such a design can effectively avoid the inward wrinkling and warping of the inner layer edge when loading the drug-eluting stent. At the same time, as the new head end, its material is soft, which can solve the problem of scratching the drug coating by the hard outer layer and play a role in protecting the drug coating. In addition, the introduced Pebax material is used as the buffer layer, providing a moderate hardness and good elasticity to promote a smoother transition. After the loading is completed, these Pebax elastic parts and the extended inner layer, which are optimized for loading, will be completely removed after the stent is successfully loaded to obtain a harder head end, which ensures the smooth progress of the stent transfer process.

[0095] By adopting the above solution, the present invention achieves seamless rigid-flexible transition from the head end to the rear end, minimizes the damage to the drug coating during the stent loading stage, and solves the problem of particle shedding of the drug layer. At the same time, it also ensures that the head end of the introduction device can provide sufficient supporting force when the stent is transferred to the microcatheter, so as to facilitate the smooth progress of the transfer process.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A stent introduction device, comprising a sheath tube and a sheath tube seat, wherein the sheath tube seat is fixedly mounted at the proximal end of the sheath tube, characterized in that: The sheath comprises an inner layer and an outer layer, the outer layer is wrapped around the surface of the inner layer, the distal end of the inner layer extends out of the distal end of the outer layer by a first length, and the friction coefficient and hardness of the inner layer are lower than those of the outer layer; a buffer layer is provided at the junction of the inner layer and the outer layer at the distal end, and the buffer layer covers the distal end of the outer layer; A cutting mark is provided at the distal end of the sheath tube near the buffer layer; The stent introduction device is used for loading the drug eluting stent. After the drug eluting stent is loaded, the inner layer and the outer layer of the sheath are cut flush along the cutting mark.

2. A stent introduction device according to claim 1, characterized in that: The buffer layer extends a second length in a proximal direction of the outer layer.

3. A stent introduction device according to claim 1, characterized in that: The buffer layer extends a third length toward the distal end of the inner layer, and the third length is not greater than the first length.

4. A stent introduction device according to claim 3, characterized in that: The thickness of the portion of the buffer layer located on the surface of the inner layer gradually changes toward the distal end.

5. A stent introduction device according to claim 4, characterized in that: The thickness of the portion of the buffer layer located on the surface of the inner layer gradually decreases toward the distal end.

6. A stent introduction device according to claim 1, characterized in that: The sheath tube is hollow, and the outer diameter of the sheath tube gradually decreases from the proximal end to the distal end.

7. A stent introduction device according to claim 1, characterized in that: The sheath tube and the sheath tube seat are integrally formed by injection molding.

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