Expandable catheter sheath and method of making same

Abstract

The application discloses an expandable catheter sheath and a preparation method thereof. The expandable catheter sheath comprises an expandable sheath and an expander. The expander comprises a spindle-shaped pushing head, which is used for extending into the expandable sheath and expanding the expandable sheath. The expandable tube body comprises, from proximal to distal, a proximal tube body, a tapered reducing section and an expandable working section. The proximal tube body is connected with a sheath tube joint. The proximal tube body, the tapered reducing section and the expandable working section all comprise a three-layer composite tube. The three-layer composite tube comprises an outer tube, a middle tube and an inner tube. The inner tube corresponding to the tapered reducing section is folded along a first axial folding joint and exposed to the outer surface of the outer tube to form a first folding structure. The inner tube corresponding to the expandable working section is folded along a second axial folding joint and partially exposed to the outer surface of the outer tube to form a second folding structure. The expandable catheter sheath provided by the application balances the three performances of rigid support, flexibility and low resistance, and has good use safety.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to an expandable catheter sheath and its preparation method. Background Technology

[0002] In the field of minimally invasive vascular interventional therapy, various catheter-based devices are typically required for diagnosis, tissue collection, angiography, and treatment. These catheter-based devices establish a channel between the outside and inside of the body. To ensure the smooth entry of other interventional devices, the sheath typically possesses a certain radial rigidity to maintain the blood vessel's stability without deformation. However, prolonged stretching of the blood vessel can easily lead to vascular complications such as spasm, causing damage to the patient. Therefore, it is necessary to design a catheter sheath that facilitates the entry of other interventional devices while minimizing the load on the patient's blood vessels. Summary of the Invention

[0003] This application provides an expandable catheter sheath and a method for preparing the same. The expandable catheter sheath provided by this application balances three major properties: rigid support, flexibility, and low passage resistance, while also having good safety in use.

[0004] On the one hand, this application provides an expandable catheter sheath, including an expandable sheath and a dilator, wherein the dilator is used to extend into the expandable sheath to expand the expandable sheath; The expandable sheath includes an expandable tube body and a sheath connector that are fixedly connected. The expandable tube body includes, from proximal to distal, a proximal tube body, a tapered variable diameter section, and an expandable working section. The proximal tube body is connected to the sheath connector. The proximal tube, the tapered variable diameter section, and the expandable working section all comprise a three-layer composite tube, which includes an outer tube, a middle tube, and an inner tube. The elasticity of the outer tube 101 is less than that of the middle tube 102. The tapered variable diameter section is provided with a first axial folding seam, and a portion of the inner tube corresponding to the tapered variable diameter section is folded along the first axial folding seam and exposed on the outer surface of the outer tube to form a first folding structure. The expandable working section is provided with a second axial folding seam, and a portion of the inner tube corresponding to the expandable working section is folded along the second axial folding seam and partially exposed on the outer surface of the outer tube to form a second folding structure.

[0005] In one exemplary embodiment, the outer tube in the first folded structure is C-shaped.

[0006] In one exemplary embodiment, the outer tube in the second folded structure is shaped like the number "6".

[0007] In one exemplary embodiment, when the expandable working section is fully expanded and deployed, the outer tube forms a complete circular tube shape.

[0008] In one exemplary embodiment, the material of the outer tube includes HDPE; The material of the middle layer tube is selected from at least one of PU, TPU, and Pebax; The material of the inner tube includes PTFE.

[0009] In one exemplary embodiment, the outer tube, the middle tube, and the inner tube are folded and then combined by high-temperature coating to form the three-layer composite tube.

[0010] In one exemplary embodiment, a guide groove is provided inside the expandable tube, the guide groove being at least partially disposed on the proximal end of the tube, and the guide groove communicating with the fold seam of the tapered variable diameter section.

[0011] In one exemplary embodiment, the guide groove 115 extends axially from the proximal tube body 111 and continuously extends to the tube wall of the tapered variable diameter section 112.

[0012] In one exemplary embodiment, a TIP tube is provided at the distal end of the expandable working section, and the proximal end of the TIP tube has the same size as the expandable working section before expansion; an easy-tear opening is provided on the side of the TIP tube near the expandable working section.

[0013] In one exemplary embodiment, the expander includes a push tube and a push head, the push head being disposed near the distal end of the push tube and being spindle-shaped.

[0014] In one exemplary embodiment, the sheath connector includes a first housing, a first sealing cap, a hemostatic valve assembly, a diaphragm tube, a second sealing cap, a duckbill valve, a two-way valve with an extension tube, a three-way valve with an extension tube, and a second housing; The two-way valve with an extension tube is disposed on the first housing, and the three-way valve with an extension tube is disposed on the second housing. The first sealing cap, the hemostatic valve assembly, the diaphragm tube, the second sealing cap, and the duckbill valve are disposed in the space formed by the first housing and the second housing. The diaphragm tube is disposed inside the hemostatic valve assembly. One end of the hemostatic valve assembly is connected to the first sealing cap, and the other end of the hemostatic valve assembly is connected to the second sealing cap. The end of the second sealing cap away from the hemostatic valve assembly is connected to the duckbill valve. The second housing is connected to the proximal tube body.

[0015] In one exemplary embodiment, the first sealing cap, the hemostatic valve assembly, the diaphragm tube, the second sealing cap, and the two-way valve with extension tube form a hemostatic valve, which is used to seal blood. The membrane tube is waist-shaped, and the material of the membrane tube is selected from at least one of UPE and PTFE.

[0016] In one exemplary embodiment, the duckbill valve has a cross-shaped structure on the side near the second housing and is radially recessed inward.

[0017] On the other hand, a method for preparing an expandable catheter sheath is provided, wherein the expandable catheter sheath is as described above, and the preparation method includes: S1. Inner tube folding pre-forming process: The inner tube is fitted onto the metal liner, and the portion of the inner tube corresponding to the tapered diameter section is folded along the first axial folding seam to form a first folding structure. The portion of the inner tube corresponding to the expandable working section is folded along the second axial folding seam to form a second folding structure. Heat shrink tubing is fitted onto the outside of the folded inner tube, and the folding seam of the inner tube is pre-shaped using a high-temperature coating method and then naturally cooled. S2. Three-layer tube composite molding: The outer tube and the middle tube are cut simultaneously. The cut outer tube and the middle tube are sequentially fitted onto the surface of the pre-shaped inner tube, so that the folded part of the inner tube is exposed through the cut seams of the outer tube and the middle tube and adheres to the surface of the outer tube. Heat shrink tubing is then fitted onto the outer layer of the pre-fitted three-layer tube. The composite bonding of the inner tube, the middle tube, and the outer tube is achieved through a high-temperature coating process. After natural cooling, the heat shrink tubing is peeled off to obtain an expandable tube body. S3. Expandable sheath assembly: The proximal end of the expandable tube is fixedly connected to the sheath tube connector to assemble the expandable sheath. S4. Preparation and adaptation of the matching expander: Based on the overall size of the expandable sheath, prepare the expander with a push head. The push head of the expander can pass through the sheath tube joint and extend into the interior of the expandable tube body for expanding the expandable tube body, and adapt to the subsequent interventional instruments.

[0018] In one exemplary embodiment, the process parameters for the inner tube folding pre-forming process include: hot air die head temperature of 220°C, operating speed of 0.3 mm / s, and air pressure of 30 kPa.

[0019] In one exemplary embodiment, the expandable tube is sequentially formed from the proximal end to the distal end into an integral structure consisting of the proximal tube, the tapered variable diameter section, and the expandable working section; and differentiated process parameters are adopted for the high-temperature coating process of different tube sections: when passing through the proximal tube and the expandable working section, the hot air die temperature is 200°C, the operating speed is 0.3 mm / s, and the air pressure is 30 kPa; when passing through the tapered variable diameter section, the hot air die temperature is 190°C, the operating speed is 0.4 mm / s, and the air pressure is 25 kPa.

[0020] The expandable catheter sheath and its preparation method provided in this application have the following technical advantages: This application's expandable catheter sheath includes an expandable sheath and a dilator. The dilator is inserted into the expandable sheath to expand it. The expandable sheath includes a fixedly connected expandable tube body and a sheath connector. The expandable tube body, from proximal to distal, includes a proximal tube body, a tapered diameter section, and an expandable working section. The proximal tube body is connected to the sheath connector. The proximal tube body, tapered diameter section, and expandable working section all include a three-layer composite tube, which includes an outer tube, a middle tube, and an inner tube. The elasticity of the outer tube is less than that of the middle tube. The tapered diameter section is provided with a first axial folding slit, and the portion of the inner tube corresponding to the tapered diameter section is folded along the first axial folding slit and exposed on the outer surface of the outer tube to form a first folding structure. The expandable working section is provided with a second axial folding slit, and the portion of the inner tube corresponding to the expandable working section is folded along the second axial folding slit and partially exposed on the outer surface of the outer tube to form a second folding structure. This application improves the folding structure and material of the tube body, designing a three-layer composite tube. The outer layer provides strong mechanical strength to the expandable tube, making it less prone to kinking and providing good support. The middle layer enhances the flexibility and elasticity of the expandable tube, reducing expansion resistance and facilitating operator manipulation. The inner layer reduces resistance when instruments pass through the tube, achieving a balance between rigid support, flexibility, and low resistance. A tapered transition section is used between the proximal tube body and the expandable working section, with different folding structures between the tapered transition section and the expandable working section. This reduces resistance during sheath expansion and ensures proper expansion. The sheath has excellent axial and circumferential rigidity, better handling instrument retraction and effectively preventing sheath damage. A guide groove within the expandable sheath reduces peak force during expansion at the tapered diameter section. An expander with a pusher head and a flow guide groove on the pusher head pre-expands the expandable sheath, significantly reducing resistance to subsequent instrument insertion, facilitating operator operation, and effectively reducing blood flow obstruction during expander insertion, minimizing hemodynamic impact. A sheath connector with a hemostatic valve assembly and a duckbill valve enhances blood sealing, preventing blood loss and improving the safety of the expandable sheath.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions and advantages in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of an expandable catheter sheath provided in the embodiments of this specification; Figure 2 This is a schematic diagram of the structure of an expandable sheath provided in the embodiments of this specification; Figure 3 This is a schematic diagram of an expandable tube provided in the embodiments of this specification; Figure 4 This is a schematic cross-sectional view of a tapered variable diameter section provided in the embodiments of this specification; Figure 5 This is a schematic cross-sectional view of an expandable working section provided in an embodiment of this specification; Figure 6 This is a schematic diagram of the structure of an expandable tube body provided in the embodiments of this specification; Figure 7 This is a schematic diagram of the cross-section of the expandable working section before and after expansion, provided in the embodiments of this specification. Figure 8 This is a comparison diagram of force values ​​before and after setting the guide groove, provided in an embodiment of this specification; Figure 9 This is a schematic diagram of a guide groove being fully disposed in the proximal tube body according to an embodiment of this specification; Figure 10 This is a schematic diagram of a guide groove portion disposed on the proximal end of the tube body, as provided in the embodiments of this specification; Figure 11 These are schematic diagrams of various guide grooves of different shapes provided in the embodiments of this specification; Figure 12 This is a schematic diagram of the structure of a TIP tube provided in the embodiments of this specification; Figure 13 This is a schematic diagram of another TIP tube structure provided in the embodiments of this specification; Figure 14 This is a schematic diagram of an expandable working section and a TIP tube provided in the embodiments of this specification; Figure 15 This is a schematic diagram of the structure of an expander provided in the embodiments of this specification; Figure 16 This is a cross-sectional schematic diagram of a push head provided in an embodiment of this specification; Figure 17 This is a schematic diagram of the structure of a push head provided in an embodiment of this specification; Figure 18 This is a schematic diagram of the structure of a sheath connector provided in the embodiments of this specification; Figure 19 This is a schematic diagram of the structure of a duckbill valve provided in the embodiments of this specification; The corresponding labels in the attached diagram are as follows: 1-Expandable sheath, 2-Expander, 11-Expandable tube body, 12-Sheath connector, 111-Proximal tube body, 112-Conical variable diameter section, 113-Expandable working section, 114-TIP tube, 1141-Easy-tear opening, 115-Guide groove, 101-Outer tube, 102-Middle tube, 103-Inner tube, 121-First housing, 122-First sealing cap, 123-Hemostatic valve assembly, 124-Membrane tube, 125-Second sealing cap, 126-Duckbill valve, 127-Two-way valve with extension tube, 128-Three-way valve with extension tube, 129-Second housing, 21-Push tube body, 22-Push head, 221-Guide groove. Detailed Implementation

[0024] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Since the embodiments disclosed in this application can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, the terms "first," "second," etc., in the specification, claims, and the above-mentioned drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0026] like Figures 1-19 As shown below, an expandable catheter sheath of this application is described, including an expandable sheath 1 and a dilator 2, wherein the dilator 2 is used to extend into the expandable sheath 1 to expand the expandable sheath 1; The expandable sheath 1 includes an expandable tube body 11 and a sheath tube connector 12 that are fixedly connected. The expandable tube body 11 includes, from proximal to distal, a proximal tube body 111, a tapered variable diameter section 112, and an expandable working section 113. The proximal tube body 111 is connected to the sheath tube connector 12. The proximal tube 111, the tapered variable diameter section 112, and the expandable working section 113 all comprise a three-layer composite tube, which includes an outer tube 101, a middle tube 102, and an inner tube 103. The elasticity of the outer tube 101 is less than that of the middle tube 102. The tapered variable diameter section 112 is provided with a first axial folding seam, and a portion of the inner tube 103 corresponding to the tapered variable diameter section 112 is folded along the first axial folding seam and exposed on the outer surface of the outer tube 101 to form a first folding structure. The expandable working section 113 is provided with a second axial folding seam, and a portion of the inner tube 103 corresponding to the expandable working section 113 is folded along the second axial folding seam and partially exposed on the outer surface of the outer tube 101 to form a second folding structure.

[0027] In the embodiments of this application, such as Figure 1As shown, the expandable catheter sheath includes an expandable sheath 1 and a dilator 2. The dilator 2 is used to expand the expandable sheath 1. Before other instruments are inserted, the expandable sheath can be pre-expanded using the dilator 2 to reduce the resistance to subsequent instrument insertion.

[0028] The expandable sheath 1 includes an expandable tube body 11 and a sheath tube connector 12 that are interconnected, such as Figure 2 and Figure 3 As shown, the expandable tubing 11 includes a proximal tubing 111, a tapered reducing section 112, and an expandable working section 113 connected in sequence. The proximal tubing 111 is a conventional tubing and is used to connect to the sheath connector 12. The inner diameter of the proximal tubing 111 is the maximum size that the expandable catheter sheath can allow to pass through. The tapered reducing section 112 connects the proximal tubing 111 and the expandable working section 113, serving as a transition structure within the expandable tubing 11. This allows for a smooth transition when the instrument passes through the tapered reducing section 112 and the expandable working section 113, reducing resistance during instrument passage. The expandable working section 113 is the main working part of the expandable catheter sheath and has a folded portion. This folded portion expands and unfolds when the instrument passes through, allowing the sheath's inner diameter to adaptively increase, allowing larger instruments to pass. After the instrument passes through, the sheath shrinks back to its initial size under the force of vascular contraction, releasing its load on the blood vessel and protecting the blood vessel from prolonged dilation to a greater extent.

[0029] The aforementioned expandable tube 11 is a three-layer composite tube structure, comprising an outer tube 101, a middle tube 102, and an inner tube 103. The elasticity of the outer tube 101 is less than that of the middle tube 102. The outer tube 101 provides the expandable tube 11 with strong mechanical strength, is not easily bent, and provides good support. The middle tube 102 enhances the flexibility and elasticity of the expandable tube 11, reduces the expansion resistance of the tube, and facilitates the operator's operation. The inner tube 103 is made of a material with a low coefficient of friction, good biocompatibility, and strong chemical inertness, reducing the resistance when instruments pass through the tube.

[0030] In this embodiment, the tapered variable diameter section 112 and the expandable working section 113 have folding structures with different folding forms. The tapered variable diameter section 112 has a first axial folding slot along its axial direction. A portion of the inner tube 103 corresponding to the tapered variable diameter section 112 extends from the first axial folding slot to the outside of the entire tube body and folds. The folded portion is exposed on the outer surface of the outer tube, forming a first folding structure with a first folding form. Figure 4This is a schematic diagram of the cross-section corresponding to the tapered variable diameter section 112. The first folding structure corresponding to the tapered variable diameter section 112 is C-shaped. When the tube is in its initial state, the cut edges of the outer tube 101 and the middle tube 102 at the tapered variable diameter section 112 are aligned. This folding structure results in uniform circumferential mechanical properties of the tube, preventing excessive stress concentration during the advancement of the sheath and insertion into the human body, thus avoiding the risk of tube damage. In addition, there is no additional overlap between the outer tube 101 and the middle tube 102 in this C-shaped structure. When the tapered variable diameter section 112 expands, it only needs to overcome the resistance between the inner tube 103 and the outer tube 101 on the outer surface of the tube, which can minimize the expansion resistance. The expandable working section 113 is provided with a second axial folding seam along its axial direction. The portion of the inner tube 103 corresponding to the expandable working section 113 extends from the second axial folding seam to the outside of the entire tube body and folds. Only a part of the folded portion is exposed on the outer surface of the outer tube, while the other part of the folded portion is wrapped by the outer tube 101, forming a second folding structure with a second folding form. Figure 5 This is a schematic diagram of the cross-section corresponding to the expandable working section 113. Figure 6 This is a schematic diagram of the structure of the expandable tube 11. The second fold structure corresponding to the expandable working section 113 is shaped like a "6". Figure 7 This is a cross-sectional diagram of the expandable working section 113 before expansion and when expanded to its maximum unfolded state. The outer tube 101 and the middle tube 102 can form a complete circular tube shape. This structure can maintain the axial and circumferential rigidity of the tube body to the greatest extent after unfolding. When the device enters or exits the sheath, the axial frictional resistance generated on the inner wall of the sheath will not cause the tube body to bend. It should be noted that when the expandable tube body 11 expands in vivo, due to the covering effect of the blood vessel wall, the folded part of the inner tube 103 located outside the outer tube 101 at the expandable working section 113 is attached to the surface of the outer tube 101; when the expandable tube body 11 expands outside the body, the folded part of the inner tube 103 located outside the outer tube 101 at the expandable working section 113 can be raised and is not attached to the surface of the outer tube 101.

[0031] In this embodiment, the width of the first axial folding slot of the tapered variable diameter section 112 gradually decreases from 25% of the circumference of the tapered variable diameter section 112 tube to 0. If the sheath is designed to expand to the fully expanded state of the inner tube 103, the width of the folding slot of the tapered variable diameter section 112 is 0 at the proximal end of the tube 111. The width of the second axial folding slot of the expandable working section 113 accounts for 25% of the circumference of the expandable working section 113 tube.

[0032] In this embodiment, for the expandable working section 113, the overlap between the folded portion of the inner tube 103 and the outer tube 101 is 10%-25% of the tube circumference, and the specific overlap can be designed according to the expandable size of the tube. For the tapered variable diameter section 112, the overlap between the folded portion of the inner tube 103 and the outer tube 101 is 0, and the folded portion of the inner tube 103 only presses against the surface of the outer tube 101.

[0033] In this embodiment, the inner tube 103 has a thinner wall thickness, so the portion of the inner tube 103 exposed outside the tube body has a smaller impact on the overall roundness of the tube body.

[0034] In this embodiment, the outer tube 101 has a wall thickness of 0.3 mm-0.4 mm, the middle tube 102 has a wall thickness of 0.1 mm-0.2 mm, and the inner tube 103 has a wall thickness of 0.05 mm-0.1 mm. Preferably, the outer tube 101 has a wall thickness of 0.3 mm, the middle tube 102 has a wall thickness of 0.1 mm, and the inner tube 103 has a wall thickness of 0.05 mm.

[0035] The expandable catheter sheath provided in this application has a small diameter when it is first inserted into the patient's body, so it does not exert any additional load on the patient's blood vessels. When a large instrument is inserted into the sheath, the inner diameter of the sheath can adaptively increase to allow the large instrument to pass through. After the instrument has passed through, the sheath can shrink back to its initial size under the force of vasoconstriction, releasing its load on the blood vessel and protecting the blood vessel from prolonged dilation to a great extent, thus exhibiting good safety in use.

[0036] In an exemplary embodiment, the outer tube 101 in the first folded structure is C-shaped.

[0037] In one exemplary embodiment, the outer tube 101 in the second folded structure is shaped like the number "6".

[0038] In an exemplary embodiment, when the expandable working section 113 is fully expanded and deployed, the outer tube 101 forms a complete circular tube shape.

[0039] In this embodiment, the expandable tube 11 includes two folding structures: a first folding structure corresponding to the tapered variable diameter section 112 and a second folding structure corresponding to the expandable working section 113. For example... Figure 4 As shown. The tapered diameter section 112 is a C-shaped fold, meaning that when the tube body of the tapered diameter section 112 is in its initial state, the cut edges of the outer tube 101 and the middle tube 102 at the tapered diameter section 112 are aligned, and both the outer tube 101 and the middle tube 102 are C-shaped. For example... Figure 5As shown, the main body of the expandable working section 113 is a figure-6 shaped fold, meaning that when the outer tube 101 and the middle tube 102 are axially cut open, the outer tube 101 is figure-6 shaped, and the middle tube 102 is C-shaped, with the middle tube 102 being wrapped by the outer tube 101. By setting folding structures with different folding forms in the expandable tube body 11, the C-shaped folding structure of the tapered diameter section 112 has uniform circumferential mechanical properties, which can compensate for the abrupt change in mechanical properties caused by the tapered diameter change. The figure-6 shaped folding structure of the expandable working section 113 enables the expanded sheath to have high axial mechanical strength.

[0040] When the expandable working section 113 is fully expanded, the outer tube 101 can form a complete circular tube shape. This structure can maintain the axial and circumferential rigidity of the tube body to the greatest extent after expansion. When the instrument enters or exits the sheath, the axial frictional resistance generated on the inner wall of the sheath will not cause the tube body to bend. It can better cope with the instrument retraction conditions. For example, in balloon catheter products, when the balloon body does not retract well, the axial rigidity of the tube body can be sufficient to resist the resistance of the balloon being forcibly withdrawn into the sheath, preventing damage to the sheath.

[0041] In one exemplary embodiment, the material of the outer tube 101 includes HDPE; The material of the middle layer tube 102 is selected from at least one of PU, TPU, and Pebax; The inner tube 103 is made of PTFE.

[0042] In this embodiment, the material of the outer tube 101 may include HDPE, which has high hardness, high rigidity, and low surface friction coefficient. This material can provide strong mechanical strength for the expandable tube 11, is not easily bent, and can provide good support under harsh access conditions such as high calcification.

[0043] The material of the middle sheath 102 is selected from at least one of PU, TPU, and Pebax. These materials are highly elastic polymers with good biocompatibility. The structure of the middle sheath 102 is consistent with that of the outer sheath 101. The middle sheath 102 can compensate for the shortcomings of the outer sheath 101, which is "too rigid and not easy to bend," and enhance the flexibility and elasticity of the sheath. In highly tortuous vascular environments, it can conform to the tortuous shape of the blood vessel, provide good passage, and reduce the external force load on the blood vessel. In addition, the expansion mechanism of the expandable tube 11 is to unfold the folded tube. The middle sheath 102 can also compensate for the disadvantage of the outer sheath 101 being difficult to unfold, reduce the expansion resistance of the tube, and facilitate the operator's operation.

[0044] The inner tube 103 is made of a material with a low coefficient of friction, good biocompatibility, and strong chemical inertness, such as PTFE. The inner tube 103 can reduce the frictional resistance between the instrument and the inner wall of the sheath when the instrument passes through the sheath.

[0045] This application embodiment uses a three-layer composite pipe containing three different performance materials to effectively balance the rigidity and flexibility of the pipe body.

[0046] In an exemplary embodiment, the outer tube 101, the middle tube 102, and the inner tube 103 are folded and then combined by high-temperature coating to form the three-layer composite tube.

[0047] In this embodiment, the outer tube 101, the middle tube 102 and the inner tube 103 are folded and then bonded together by high-temperature coating to form a three-layer composite tube, thereby reducing the interlayer bonding force of the three tubes.

[0048] Specifically, the process of forming a three-layer composite tube by high-temperature coating may include: first, fitting the inner tube 103 onto the metal liner, and folding it with the first axial fold and the second axial fold; after folding, fitting a heat-shrinkable tube onto the outer layer of the inner tube 103; pre-shaping the fold by high-temperature coating; after pre-shaping, allowing it to cool naturally; and then peeling off the heat-shrinkable tube from the surface of the inner tube 103. During pre-shaping, the temperature of the hot air die head is 220℃, the speed is 0.3 mm / s, and the air pressure is 30 kPa.

[0049] The outer tube 101 and the middle tube 102 are cut simultaneously. The cut middle tube 102 and the outer tube 101 are then fitted onto the surface of the inner tube 103, with the folded portion of the inner tube 103 exposed through the cut seam of the outer tube 101 and the middle tube 102 and adhered to the surface of the outer tube. A heat-shrink tubing is then fitted onto the outer surface of the three preliminarily bonded tubes. The outer tube 101, middle tube 102, and inner tube 103 are then bonded together using a high-temperature coating process. After natural cooling, the heat-shrink tubing is peeled off, resulting in an expandable tube 11 with two different folding structures. The expandable tube 11 includes a proximal tube 111, a tapered variable diameter section 112, and an expandable working section 113. During the high-temperature coating of the three tubes, different parameters are used when the hot air nozzle passes through the proximal tube 111, the tapered variable diameter section 112, and the expandable working section 113. Specifically, when the hot air nozzle passes through the near-end tube 111, the temperature of the hot air nozzle is 200℃, the velocity is 0.3 mm / s, and the air pressure is 30 kPa; when passing through the tapered diameter section 112, the temperature of the hot air nozzle is 190℃, the velocity is 0.4 mm / s, and the air pressure is 25 kPa; when passing through the expandable working section 113, the temperature of the hot air nozzle is 200℃, the velocity is 0.3 mm / s, and the air pressure is 30 kPa. The cooling method for the coating is natural cooling. This combination method, while ensuring that the three tubes are fused together, minimizes the interlayer bonding force of the three tubes, further reducing the initial resistance required for the expandable tube 11 to expand.

[0050] In one possible embodiment, the fabrication process of the three-layer composite pipe includes: The inner tube 103 is fitted onto the metal liner. The portion of the inner tube 103 corresponding to the tapered variable diameter section 112 is folded along the first axial folding seam to form a first folded structure. The portion of the inner tube 103 corresponding to the expandable working section 113 is folded along the second axial folding seam to form a second folded structure. After folding, a heat shrink tube is fitted onto the outer layer of the inner tube 103. The temperature of the hot air nozzle is set to 220°C, the speed to 0.3 mm / s, and the air pressure to 30 kPa. The folding seam is pre-shaped. After pre-shaping, it is allowed to cool naturally. Then, the heat shrink tube on the surface of the inner tube 103 is peeled off. The outer tube 101 and the middle tube 102 are cut simultaneously and fitted onto the surface of the inner tube 103. A heat shrink tube is then fitted onto the outer surface of the entire tube body. The temperature of the hot air nozzle is set to 200℃, the speed to 0.3 mm / s, and the air pressure to 30 kPa. The tube passes through the near end tube 111 under the above parameters. After passing through the near-end tube 111, the temperature of the hot air mold head is set to 190℃, the speed to 0.4 mm / s, and the air pressure to 25 kPa. Under the above parameters, it passes through the tapered variable diameter section 112. After passing through the tapered variable diameter section 112, the temperature of the hot air mold head is set to 200℃, the speed to 0.3 mm / s, and the air pressure to 30 kPa. Under the above parameters, it passes through the expandable working section 113. After the end, it is naturally cooled and the heat shrink tubing on the surface of the tube is peeled off, completing the combination between the outer tube 101, the middle tube 102 and the inner tube 103, resulting in a three-layer composite tube with a folded structure.

[0051] In this embodiment, the outer tube 101, the middle tube 102 and the inner tube 103 are fused together by high-temperature coating, which can effectively reduce the interlayer bonding force of the three tubes.

[0052] In an exemplary embodiment, the expandable tube 11 is provided with a guide groove 115, which is at least partially disposed on the proximal tube 111 and communicates with the fold seam of the tapered variable diameter section 112.

[0053] In an exemplary embodiment, the guide groove 115 extends axially from the proximal tube body 111 and continuously extends to the tube wall of the tapered variable diameter section 112.

[0054] In this embodiment, during the process of the instrument entering the expandable tube 11, a significant peak force occurs from the moment the instrument contacts the proximal end of the tapered variable diameter section 112 (i.e., the portion near the proximal tube 111) until the sheath is fully expanded. At this moment, the overlapping portion of the distal tube of the tapered variable diameter section 112 is expanded, and subsequently, the sheath is continuously expanded by the instrument. To reduce this peak force, this application provides a guide groove 115 at the proximal end of the tapered variable diameter section 112. At least a portion of the guide groove 115 is located on the proximal tube 111, but the guide groove 115 is always connected to the fold seam of the tapered variable diameter section 112. Figure 8 To set up a force value comparison diagram before and after the guide groove 115, Figure 8 The horizontal axis "displacement" represents the distance the expander 2 travels from the sheath joint 12 into the interior of the sheath when the expander 2 is used to pre-expand the expandable tube 11. It should be noted that the proximal tube 111 presents a complete and uniform cylindrical tube shape; therefore, the presence of the guide groove 115 has a negligible mechanical effect on it.

[0055] Figure 9 In one configuration of the guide groove 115 provided in this application, the guide groove 115 is completely disposed on the proximal tube body 111, and there is no guide groove 115 on the tapered variable diameter section 112. This configuration can ensure that the tapered variable diameter section 112 and the expandable working section 113 have complete circumferential mechanical morphology. Figure 10 Another way to set the guide groove 115 provided in this application is that part of the guide groove 115 is set on the proximal tube body 111 and part of it is set on the tapered diameter section 112. This setting makes the guide groove 115 occupy a larger proportion at the fold joint of the tapered diameter section 112, which can directly overcome the peak force that exists when the tube body is first expanded.

[0056] Figure 11 The diagram shows various guide grooves 115 of different shapes provided in this application. The axial cross-sectional shape of the guide groove 115 may include rectangles, triangles, bullet shapes, and other possible shapes. In one possible embodiment, the depth of the guide groove 115 can be 0.4 mm-0.6 mm, corresponding to the thickness of the outer tube 101 and the middle tube 102. The width of the guide groove 115 can be 1 mm-2 mm, and the axial length of the guide groove 115 can be 5 mm-10 mm. The guide groove 115 is aligned with the folding seam of the tapered variable diameter section 112, and the width of the guide groove 115 is aligned with the folding seam of the tapered variable diameter section 112, and they overlap in contact.

[0057] This application embodiment can reduce the peak force when the expandable tube 11 expands by providing a guide groove 115 inside the expandable tube 11.

[0058] In an exemplary embodiment, a TIP tube 114 is provided at the distal end of the expandable working section 113, and the proximal dimension of the TIP tube 114 is the same as the dimension of the expandable working section 113 before expansion; an easy-tear opening 1141 is provided on the side of the TIP tube 114 near the expandable working section 113.

[0059] In the embodiments of this application, such as Figures 12-14 As shown, a TIP tube 114 is provided at the distal end of the expandable working section 113. The proximal dimension of the TIP tube 114 is consistent with the dimension of the expandable working section 113 before expansion; that is, the inner and outer diameters of the TIP tube 114 are consistent with the state before expansion of the expandable working section 113, to ensure the integrity of the tube body in its initial state. Furthermore, to reduce the expansion force corresponding to the TIP tube 114 during the expansion of the expandable working section 113, an easy-tear opening 1141 can be provided on the side of the TIP tube 114 near the expandable working section 113. Specifically, the easy-tear opening 1141 is distributed along the axis, with a width of 1 mm, and the ratio between the length of the easy-tear opening 1141 and the length of the TIP tube 114 ranges from 0.3 to 0.5.

[0060] This application embodiment, by setting a TIP tube 114 at the far end of the expandable working section 113, can ensure the integrity of the tube body of the expandable working section 113 before expansion. By setting an easy-tear opening 1141 on the expandable working section, the expansion force value corresponding to the TIP tube 114 during the expansion of the expandable working section 113 can be effectively reduced.

[0061] In an exemplary embodiment, the expander 2 includes a push tube 21 and a push head 22, the push head 22 being disposed near the distal end of the push tube 21, and the push head 22 being spindle-shaped.

[0062] In this embodiment of the application, the push head 22 is provided with multiple guide grooves 221; the cross-sectional area of ​​the side of the push head 22 near the far end of the push tube 21 is greater than the cross-sectional area of ​​the side of the push head 22 away from the far end of the push tube 21.

[0063] In this embodiment, the expandable sheath 1 needs to be expanded before it can be used for the passage and use of other instruments. Therefore, this application designs an expander 2 for use with the expandable sheath 1 to expand the expandable sheath 1, such as... Figure 15 As shown, the expander 2 includes a push tube 21 and a push head 22. The push head 22 is located at the distal end of the push tube 21 and is used to follow the push tube 21 into the expandable sheath 1 to expand the tapered variable diameter section 112 and the expandable working section 113. Specifically, the push head 22 is spindle-shaped, and its cross-sectional shape is as follows: Figure 16As shown, it exhibits a "large head, small tail" shape, meaning the cross-sectional area on the side closer to the distal end of the push tube 21 is larger than the cross-sectional area on the side farther from the distal end of the push tube 21. The distal hammer angle of the push head 22 is 45°-60°, and the proximal hammer angle is 10°-40°. Compared to using instruments to directly enter the sheath for expansion, the push head 22 in this application has a smaller contact area with the inner wall of the sheath (only the head contacts), resulting in lower frictional resistance and a larger locally generated radial expansion force. This allows for easier unfolding of the folded portion of the sheath, facilitating operator manipulation.

[0064] In this embodiment, the push head 22 is provided with multiple guide grooves 221. Figure 17 This is a schematic diagram of the structure of a pusher head 22 provided in this application. The guide groove 221 is arranged along the axial direction of the sheath. When the pusher head 22 enters the interior of the sheath and expands forward, the guide groove 221 can guide the blood flow, effectively reduce the obstruction of blood flow, and reduce the impact on the patient's hemodynamics.

[0065] Specifically, there can be 6-8 guide grooves 221, which are evenly distributed along the circumference of the push head 22. The depth of the guide grooves 221 accounts for 50%-80% of the outer diameter of the push head 22.

[0066] In this embodiment of the application, by providing an expander 2 with a push head 22, the folded portion of the expandable tube 11 can be unfolded more easily, which facilitates operation. By providing a guide groove 221 on the push head 22, the obstruction of blood flow can be effectively reduced.

[0067] In an exemplary embodiment, the sheath connector 12 includes a first housing 121, a first sealing cap 122, a hemostatic valve assembly 123, a diaphragm tube 124, a second sealing cap 125, a duckbill valve 126, a two-way valve with an extension tube 127, a three-way valve with an extension tube 128, and a second housing 129. The two-way valve with extension tube 127 is disposed on the first housing 121, and the three-way valve with extension tube 128 is disposed on the second housing 129. The first sealing cap 122, the hemostatic valve assembly 123, the diaphragm tube 124, the second sealing cap 125, and the duckbill valve 126 are disposed in the space formed by the first housing 121 and the second housing 129. The diaphragm tube 124 is disposed inside the hemostatic valve assembly 123. One end of the hemostatic valve assembly 123 is connected to the first sealing cap 122, and the other end of the hemostatic valve assembly 123 is connected to the second sealing cap 125. The end of the second sealing cap 125 away from the hemostatic valve assembly 123 is connected to the duckbill valve 126. The second housing 129 is connected to the proximal tube 111.

[0068] In an exemplary embodiment, the first sealing cap 122, the hemostatic valve assembly 123, the diaphragm tube 124, the second sealing cap 125, and the two-way valve with extension tube 127 form a hemostatic valve for sealing blood. The membrane tube 124 is waist-shaped and is made of UPE or PTFE.

[0069] In the embodiments of this application, such as Figure 18 As shown, the sheath connector 12 includes a first housing 121, a first sealing cap 122, a hemostatic valve assembly 123, a diaphragm tube 124, a second sealing cap 125, a duckbill valve 126, a two-way valve with an extension tube 127, a three-way valve with an extension tube 128, and a second housing 129. The first sealing cap 122, hemostatic valve assembly 123, diaphragm tube 124, second sealing cap 125, and duckbill valve 126 are all disposed within the space formed by the first housing 121 and the second housing 129. The two-way valve with an extension tube 127 is disposed on the first housing 121, and the three-way valve with an extension tube 128 is disposed on the second housing 129. The first sealing cap 122, hemostatic valve assembly 123, diaphragm tube 124, second sealing cap 125, and two-way valve with an extension tube 127 constitute a hemostatic valve for sealing blood and preventing blood loss. The diaphragm tube 124 is preferably made of a material with a low coefficient of friction, such as UPE or PTFE. The waist-shaped component in the middle of the hemostatic valve assembly 123 is preferably made of silicone rubber elastomer. In use, a certain amount of water is injected into the hemostatic valve assembly 123 through the two-way valve with extension tube 127, causing the silicone rubber of the hemostatic valve assembly 123 to expand and deform. The water pressure can squeeze the membrane tube 124 in the middle, sealing the channel and thus achieving a sealing effect.

[0070] This embodiment of the application, by providing a sheath connector 12 with a hemostatic valve assembly 123, can seal blood, prevent blood loss, and improve the safety of use of the expandable sheath 1.

[0071] In an exemplary embodiment, the duckbill valve 126 has a cross-shaped structure on the side near the second housing 129 and is radially recessed inward.

[0072] In this embodiment, to further improve the sealing effect of the hemostatic valve and prevent extreme situations such as valve failure due to damage to the diaphragm tube 124, such as... Figure 19 As shown, the duckbill valve 126 at the bottom of the hemostatic valve has a cross-shaped structure on the side near the second housing 129, and is radially recessed inward. When the instrument passes through the duckbill valve 126, it provides radially inward squeezing force, thereby improving the sealing effect. The duckbill valve 126 is preferably made of silicone rubber elastomer.

[0073] This embodiment improves the tube's folding structure and material by designing a three-layer composite tube. The outer tube 101 provides strong mechanical strength to the expandable tube 11, making it less prone to folding and providing good support. The middle tube 102 enhances the flexibility and elasticity of the expandable tube 11, reducing expansion resistance and facilitating operator manipulation. The inner tube 103 reduces resistance when instruments pass through the tube, achieving a balance between rigid support, flexibility, and low resistance. A tapered transition section 112 is provided between the proximal tube 111 and the expandable working section 113 for transition. Folding structures with different folding forms are used between the tapered transition section 112 and the expandable working section 113 to reduce resistance during sheath expansion and ensure expansion. The sheath has good axial and circumferential rigidity, which can better cope with the instrument retraction condition and effectively prevent sheath damage. By setting a guide groove 115 in the expandable sheath 11, the peak force during the expansion of the tapered variable diameter section 112 can be reduced. By setting an expander 2 with a pusher head 22 and a guide groove 221 on the pusher head 22, the expandable sheath 11 can be pre-expanded, thereby greatly reducing the resistance to subsequent instrument entry, facilitating the operator's operation, and effectively reducing the obstruction of blood flow when the expander 2 is pushed into the blood vessel, reducing the impact on hemodynamics. By setting a sheath connector 12 with a hemostatic valve assembly 123 and a duckbill valve 126, the sealing effect on blood can be improved, preventing blood loss and improving the safety of use of the expandable sheath 1.

[0074] The following describes a method for preparing an expandable catheter sheath provided in this application. The preparation method includes: S1. Pre-forming folding of inner tube 103: The inner tube 103 is fitted onto the metal liner. The portion of the inner tube 103 corresponding to the tapered variable diameter section 112 is folded along the first axial folding seam to form a first folded structure. The portion of the inner tube 103 corresponding to the expandable working section 113 is folded along the second axial folding seam to form a second folded structure. A heat shrink tubing is fitted onto the outside of the folded inner tube 103. The folding seam of the inner tube 103 is pre-formed using a high-temperature coating method and then naturally cooled. S2. Three-layer tube composite molding: The outer tube 101 and the middle tube 102 are cut simultaneously. The cut outer tube 101 and the middle tube 102 are sequentially fitted onto the surface of the pre-shaped inner tube 103, so that the folded part of the inner tube 103 is exposed through the cut seams of the outer tube 101 and the middle tube 102 and adhered to the surface of the outer tube 101. Heat shrink tubing is then fitted onto the outer layer of the initially bonded three-layer tube. The composite bonding of the inner tube 103, the middle tube 102, and the outer tube 101 is achieved through a high-temperature coating process. After natural cooling, the heat shrink tubing is peeled off to obtain the expandable tube body 11. S3. Assembly of expandable sheath 1: The proximal end of the expandable tube 111 is fixedly connected to the sheath joint 12 to assemble the expandable sheath 1. S4. Preparation and adaptation of the matching expander 2: Based on the overall size of the expandable sheath 1, the expander 2 with a push head 22 is prepared. The push head 22 of the expander 2 can pass through the sheath tube joint 12 and extend into the interior of the expandable tube 11 for expanding the expandable tube 11 and adapting to the entry of subsequent interventional instruments.

[0075] In an exemplary embodiment, the process parameters for the folding and pre-forming process of the inner tube 103 include: hot air head temperature of 220°C, operating speed of 0.3 mm / s, and air pressure of 30 kPa.

[0076] In an exemplary embodiment, the expandable tube 11 is sequentially formed from the proximal end to the distal end into an integral structure consisting of the proximal tube 111, the tapered variable diameter section 112, and the expandable working section 113; and differentiated process parameters are adopted for the high-temperature coating process of different tube sections: when passing through the proximal tube 111 and the expandable working section 113, the hot air die head temperature is 200°C, the operating speed is 0.3 mm / s, and the air pressure is 30 kPa; when passing through the tapered variable diameter section 112, the hot air die head temperature is 190°C, the operating speed is 0.4 mm / s, and the air pressure is 25 kPa.

[0077] In this embodiment, the inner tube 103 is first fitted onto the metal liner and folded. The portion of the inner tube 103 corresponding to the tapered variable diameter section 112 is folded along the first axial folding seam to form a first folded structure. The portion of the inner tube 103 corresponding to the expandable working section 113 is folded along the second axial folding seam to form a second folded structure. After folding, a heat-shrinkable tube is fitted onto the outer layer of the inner tube 103. The folding seam is pre-shaped by high-temperature coating. After pre-shaping, it is allowed to cool naturally, and then the heat-shrinkable tube on the surface of the inner tube 103 is peeled off. During pre-shaping, the temperature of the hot air nozzle is 220°C, the speed is 0.3 mm / s, and the air pressure is 30 kPa.

[0078] The outer tube 101 and the middle tube 102 are cut simultaneously, and the cut outer tube 101 and the middle tube 102 are fitted onto the surface of the pre-shaped inner tube 103. The folded part of the inner tube 103 is exposed through the cut seam of the outer tube 101 and the middle tube 102 and adheres to the surface of the outer tube. A heat shrink tube is then fitted onto the outer surface of the three pre-fitted tubes, and the outer tube 101, the middle tube 102 and the inner tube 103 are bonded together by high-temperature coating. After natural cooling, the heat shrink tube is peeled off, resulting in an expandable tube 11 with two different folding structures. The expandable tube 11 includes, from proximal end to distal end, a proximal tube 111, a tapered variable diameter section 112 and an expandable working section 113. When applying a high-temperature coating to the three-layer tube, differentiated process parameters are used when the hot air die passes through the near-end tube 111, the tapered diameter section 112, and the expandable working section 113. Specifically, when the hot air die passes through the near-end tube 111, the temperature is 200℃, the velocity is 0.3 mm / s, and the air pressure is 30 kPa; when passing through the tapered diameter section 112, the temperature is 190℃, the velocity is 0.4 mm / s, and the air pressure is 25 kPa; and when passing through the expandable working section 113, the temperature is 200℃, the velocity is 0.3 mm / s, and the air pressure is 30 kPa. This high-temperature coating method reduces the interlayer bonding force of the three-layer tube, thereby reducing the initial resistance required for the expandable tube 11 to expand.

[0079] A membrane tube 124 is placed inside the hemostatic valve assembly 123, and a first sealing cap 122 and a second sealing cap 125 are respectively provided at both ends of the hemostatic valve assembly 123 for sealing. Together with the two-way valve with extension tube 127, a hemostatic valve is formed to seal blood, resulting in a sheath connector 12 with a hemostatic valve. The sheath connector 12 is then connected to the proximal tube 111 of the expandable tube body 11 to obtain the expandable sheath 1.

[0080] An expander 2 with a pusher head 22 is prepared according to the size of the expandable sheath 1, so that the pusher head 22 can pass through the sheath tube joint 12 and enter the expandable tube 11 to expand the expandable tube 11, which facilitates the entry of subsequent instruments.

[0081] As can be seen from the expandable catheter sheath and its preparation method provided in this application, the expandable catheter sheath of this application includes an expandable sheath and an expander. The expandable sheath is used to insert into the expandable sheath to expand it. The expandable sheath includes a fixedly connected expandable tube body and a sheath connector. The expandable tube body includes, from proximal to distal, a proximal tube body, a tapered diameter section, and an expandable working section. The proximal tube body is connected to the sheath connector. The elasticity of the outer tube is less than that of the middle tube. The proximal tube body, the tapered diameter section, and the expandable working section all include a three-layer composite tube, which includes an outer tube, a middle tube, and an inner tube. The tapered diameter section is provided with a first axial folding slit. The portion of the inner tube corresponding to the tapered diameter section is folded along the first axial folding slit and exposed on the outer surface of the outer tube to form a first folding structure. The expandable working section is provided with a second axial folding slit. The portion of the inner tube corresponding to the expandable working section is folded along the second axial folding slit and partially exposed on the outer surface of the outer tube to form a second folding structure. This application improves the folding structure and material of the tube body, designing a three-layer composite tube. The outer layer provides strong mechanical strength to the expandable tube, making it less prone to kinking and providing good support. The middle layer enhances the flexibility and elasticity of the expandable tube, reducing expansion resistance and facilitating operator manipulation. The inner layer reduces resistance when instruments pass through the tube, achieving a balance between rigid support, flexibility, and low resistance. A tapered transition section is used between the proximal tube body and the expandable working section, with different folding structures between the tapered transition section and the expandable working section. This reduces resistance during sheath expansion and ensures proper expansion. The sheath has excellent axial and circumferential rigidity, better handling instrument retraction and effectively preventing sheath damage. A guide groove within the expandable sheath reduces peak force during expansion at the tapered diameter section. An expander with a pusher head and a flow guide groove on the pusher head pre-expands the expandable sheath, significantly reducing resistance to subsequent instrument insertion, facilitating operator operation, and effectively reducing blood flow obstruction during expander insertion, minimizing hemodynamic impact. A sheath connector with a hemostatic valve assembly and a duckbill valve enhances blood sealing, preventing blood loss and improving the safety of the expandable sheath.

[0082] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An expandable catheter sheath, characterized in that, It includes an expandable sheath (1) and an expander (2), the expander (2) being inserted into the expandable sheath (1) to expand the expandable sheath (1); The expandable sheath (1) includes an expandable tube body (11) and a sheath tube connector (12) that are fixedly connected. The expandable tube body (11) includes a proximal tube body (111), a tapered variable diameter section (112), and an expandable working section (113) from near to far. The proximal tube body (111) is connected to the sheath tube connector (12). The proximal tube (111), the tapered variable diameter section (112), and the expandable working section (113) all include a three-layer composite tube, which includes an outer tube (101), a middle tube (102), and an inner tube (103). The elasticity of the outer tube (101) is less than that of the middle tube (102). The tapered variable diameter section (112) is provided with a first axial folding seam, and the portion of the inner tube (103) corresponding to the tapered variable diameter section (112) is folded along the first axial folding seam and exposed on the outer surface of the outer tube (101) to form a first folding structure. The expandable working section (113) is provided with a second axial folding seam, and the portion of the inner tube (103) corresponding to the expandable working section (113) is folded along the second axial folding seam and partially exposed on the outer surface of the outer tube (101) to form a second folding structure. The outer tube (101) in the first folded structure has a C-shaped cross-section; the outer tube (101) in the second folded structure has a "6" shaped cross-section.

2. The expandable catheter sheath according to claim 1, characterized in that, When the expandable working section (113) is fully expanded and unfolded, the outer tube (101) forms a complete circular tube shape.

3. The expandable catheter sheath according to claim 1, characterized in that, The material of the outer tube (101) includes HDPE; The material of the middle layer tube (102) is selected from at least one of PU and Pebax; The material of the inner tube (103) includes PTFE.

4. The expandable catheter sheath according to claim 3, characterized in that, The outer tube (101), the middle tube (102) and the inner tube (103) are folded and then combined by high-temperature coating to form the three-layer composite tube.

5. The expandable catheter sheath according to claim 1, characterized in that, The expandable tube (11) is provided with a guide groove (115), which is at least partially provided on the proximal tube (111) and is connected to the fold seam of the tapered variable diameter section (112).

6. The expandable catheter sheath according to claim 5, characterized in that, The guide groove (115) extends axially from the proximal tube body (111) and continuously extends to the tube wall of the tapered variable diameter section (112).

7. The expandable catheter sheath according to claim 1, characterized in that, The distal end of the expandable working section (113) is provided with a TIP tube (114), the proximal end of the TIP tube (114) is the same as the size of the expandable working section (113) before expansion; the side of the TIP tube (114) near the expandable working section (113) is provided with an easy-tear opening (1141).

8. The expandable catheter sheath according to claim 1, characterized in that, The expander (2) includes a push tube (21) and a push head (22), the push head (22) being disposed near the far end of the push tube (21), and the push head (22) being spindle-shaped.

9. The expandable catheter sheath according to claim 1, characterized in that, The sheath connector (12) includes a first housing (121), a first sealing cap (122), a hemostatic valve assembly (123), a membrane tube (124), a second sealing cap (125), a duckbill valve (126), a two-way valve with an extension tube (127), a three-way valve with an extension tube (128), and a second housing (129). The two-way valve with extension tube (127) is disposed on the first housing (121), the three-way valve with extension tube (128) is disposed on the second housing (129), the first sealing cap (122), the hemostatic valve assembly (123), the diaphragm tube (124), the second sealing cap (125) and the duckbill valve (126) are disposed in the space formed by the first housing (121) and the second housing (129), the diaphragm tube (124) is disposed inside the hemostatic valve assembly (123), one end of the hemostatic valve assembly (123) is connected to the first sealing cap (122), the other end of the hemostatic valve assembly (123) is connected to the second sealing cap (125), the end of the second sealing cap (125) away from the hemostatic valve assembly (123) is connected to the duckbill valve (126), and the second housing (129) is connected to the proximal tube body (111).

10. The expandable catheter sheath according to claim 9, characterized in that, The first sealing cap (122), the hemostatic valve assembly (123), the membrane tube (124), the second sealing cap (125), and the two-way valve with extension tube (127) form a hemostatic valve, which is used to seal blood. The membrane tube (124) is waist-shaped with the middle narrowing towards both ends, and the material of the membrane tube (124) is selected from at least one of UPE and PTFE.

11. The expandable catheter sheath according to claim 10, characterized in that, The duckbill valve (126) has a cross-shaped structure on the side near the second housing (129) and is radially recessed inward.

12. A method for preparing an expandable catheter sheath as described in any one of claims 1-11, characterized in that, The preparation method includes: S1. Pre-forming treatment of inner tube (103) folding: The inner tube (103) is fitted onto the metal liner. The portion of the inner tube (103) corresponding to the tapered variable diameter section (112) is folded along the first axial folding seam to form a first folding structure. The portion of the inner tube (103) corresponding to the expandable working section (113) is folded along the second axial folding seam to form a second folding structure. Heat shrink tubing is fitted onto the outside of the folded inner tube (103). The folding seam of the inner tube (103) is pre-formed using a high-temperature coating method and then naturally cooled. S2. Three-layer tube composite molding: The outer tube (101) and the middle tube (102) are cut simultaneously. The cut outer tube (101) and the middle tube (102) are sequentially fitted onto the surface of the pre-shaped inner tube (103), so that the folded part of the inner tube (103) is exposed by the cut seam of the outer tube (101) and the middle tube (102) and adhered to the surface of the outer tube (101). Heat shrink tubing is then fitted onto the outer layer of the initially bonded three-layer tube. The composite bonding of the inner tube (103), the middle tube (102), and the outer tube (101) is achieved through a high-temperature coating process. After natural cooling, the heat shrink tubing is peeled off to prepare an expandable tube body (11). S3. Assembly of expandable sheath (1): The proximal tube (111) of the expandable tube (11) is fixedly connected to the sheath tube connector (12) to assemble the expandable sheath (1). S4. Preparation and adaptation of the matching expander (2): Based on the overall size of the expandable sheath (1), the expander (2) with a pusher head (22) is prepared. The pusher head (22) of the expander (2) can pass through the sheath joint (12) and extend into the interior of the expandable tube (11) for expanding the expandable tube (11) and adapting to the entry of subsequent interventional instruments.

13. The method for preparing the expandable catheter sheath according to claim 12, characterized in that, The process parameters for the pre-forming folding of the inner tube (103) include: hot air head temperature 220℃, running speed 0.3 mm / s, and air pressure 30 kPa.

14. The method for preparing the expandable catheter sheath according to claim 12, characterized in that, The expandable tube (11) is formed sequentially from the proximal end to the distal end into an integral structure: the proximal tube (111), the tapered variable diameter section (112), and the expandable working section (113). Different process parameters are adopted for the high-temperature coating process of different tube sections: when passing through the proximal tube (111) and the expandable working section (113), the hot air die head temperature is 200℃, the running speed is 0.3 mm / s, and the air pressure is 30 kPa; when passing through the tapered variable diameter section (112), the hot air die head temperature is 190℃, the running speed is 0.4 mm / s, and the air pressure is 25 kPa.

Images