CN218589493U - Expandable catheter sheath and interventional medical device - Google Patents

Abstract

The utility model provides an expandable catheter sheath and an interventional medical device, wherein the catheter sheath comprises an elastic outer sleeve and a flexible inner sleeve which are nested, and the inner sleeve comprises an outer layer structure and an inner layer structure; the outer layer structure is provided with a notch groove arranged along the axial direction, and the inner layer structure is in a cylindrical shape which is closed in the circumferential direction; when the catheter sheath does not bear external expansion force, the diameter of the outer sleeve is the minimum, and the part of the inner layer structure corresponding to the notch groove is folded on the radial inner side to form a first folding wing and a second folding wing which are symmetrical; when the catheter sheath bears external expansion force, the first folding wings and the second folding wings of the inner layer structure are at least partially unfolded, and the outer sleeve is elastically deformed to be enlarged in diameter. The utility model discloses a structural style provides obvious facility for the concrete operation of interior sleeve pipe embedding outer tube in the manufacturing process, can show the production manufacturing efficiency who promotes the pipe sheath.

Description

Expandable catheter sheath and interventional medical device

Technical Field

The utility model relates to the field of medical equipment, in particular to an expandable catheter sheath and an interventional medical equipment.

Background

When performing a surgical procedure (e.g., a heart valve transplantation procedure) using an interventional medical device introduced into the body, the interventional medical device generally includes a sheath with a sealing hemostatic valve, and a medical member passing through the sheath, the sheath is introduced into the body to primarily deliver a medical component, and the medical component is delivered to the surgical site through the sheath, and the diameter of the sheath is required to be expandable to reduce patient discomfort during the surgical procedure.

The utility model discloses expandable sheath before usually includes outer catheter and inner catheter, in the manufacturing process, partly outside folding formation winged folding portion of inner catheter earlier, then put into the cross-section for circular shape elasticity outer catheter in, the elasticity through outer catheter returns the power and cramps it, thereby it gets into the human body to be convenient for at the operation initial stage to make the sheath whole keep a less external diameter, and in follow-up operation, when the medical component that the size is great relatively passes this sheath, the sheath is owing to receive the effect of expansion external force, the outside folding part of inner catheter expandes, make the internal diameter grow of inner catheter supply the medical component to pass smoothly. However, the operation of inserting the inner catheter into the flexible outer catheter after the inner catheter is folded outwardly to form the folded portion is complicated, and the operator must be careful not to damage the original shape of the folded portion.

SUMMERY OF THE UTILITY MODEL

Based on the above current situation, the main object of the present invention is to provide an expandable sheath and interventional medical device, which can overcome the above problems in the prior art and facilitate installation and manufacture.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

in a first aspect, the present invention provides an expandable introducer sheath comprising an outer sleeve and an inner sleeve in a nested arrangement, the outer sleeve having a resiliency to apply a radially inward cinching force to the inner sleeve,

the inner sleeve comprises an outer layer structure and an inner layer structure; the outer layer structure is provided with a notch groove arranged along the axial direction, so that the cross section of the outer layer structure is in a circular arc shape which is not closed in the circumferential direction; the inner layer structure is a flexible structure and is in a cylindrical shape which is closed in the circumferential direction, and the inner wall of the outer layer structure is attached and connected with one part of the outer wall of the inner layer structure;

the outer sleeve has a minimum diameter when the dilatation catheter sheath is not subjected to an external dilatation force; the first groove edge and the second groove edge of the notch groove of the outer layer structure are close to each other, so that the diameter of the outer layer structure is reduced; the part of the inner layer structure corresponding to the notch groove is folded at the radial inner side to form a first folding wing and a second folding wing which are symmetrical;

when the expansion catheter sheath bears an external expansion force, the first groove edge and the second groove edge of the notch groove of the outer layer structure are far away from each other, so that the diameter of the outer layer structure is enlarged, the first folding wing and the second folding wing of the inner layer structure are at least partially unfolded, and the outer sleeve is elastically deformed to be enlarged in diameter.

Preferably, the inner layer structure is provided with a first fold at each of the positions of the first slot edge and the second slot edge, and two second folds are further provided between the two first folds.

Preferably, the inner sleeve has an overall length of 320-400mm, and in an initial state before the catheter sheath is expanded, the inner sleeve extends from the rear end surface of the inner sleeve by a length of 40-110mm, the folding degree of the inner layer structure is gradually increased, so that the outer diameter of the inner sleeve is gradually decreased.

Preferably, the rear end face of the outer sleeve is flush with the rear end face of the inner sleeve, and the outer sleeve at least covers the part of the inner sleeve with the gradually reduced outer diameter to form the outer sleeve with at least a reducing part.

Preferably, the front end of the catheter sheath is provided with an axial protruding part, the axial protruding part comprises an equal-diameter extending part and a narrowing part which are integrally connected, the narrowing part is located at the front end of the equal-diameter extending part, the outer contour of the narrowing part is in a truncated cone shape, the axial protruding part is provided with at least one pre-tearing groove, and the pre-tearing groove extends from the equal-diameter extending part to the narrowing part but does not penetrate through the front end of the narrowing part; under the action of the expanding external force, the front end part of the narrowing part can be torn to penetrate through to the front end along the pre-tearing groove.

Preferably, the front end of the outer layer structure is located inside the equal-diameter extension part, and the equal-diameter extension part is fixedly connected with the front end of the outer layer structure through welding.

Preferably, the number of the pre-tearing grooves is one, and the positions of the pre-tearing grooves in the circumferential direction correspond to the notch grooves of the outer layer structure.

Preferably, each crease is parallel to each other, and the portion of each pre-tear groove on the constant diameter extension is parallel to the first crease.

Preferably, the surface of the outer sleeve is provided with a hydrophilic coating; the wall thickness of the outer sleeve is 0.05-0.5mm.

Preferably, the shore hardness of the inner layer structure is smaller than that of the outer layer structure, and the shore hardness of the outer sleeve is larger than that of the outer layer structure.

In a second aspect, the present invention provides an interventional medical device comprising a catheter sheath as described above.

The utility model discloses a make the pipe sheath including nested outer tube and the interior sleeve pipe that sets up, interior sleeve pipe includes outer structure and inner structure, the position corresponding to outer structure's breach groove of inner structure is folded in radial inboard, form first folding wing and the second folding wing, make interior sheathed tube outline basic rule and do not have outside arch, pipe sheath external diameter is less relatively when having kept not bearing expansion external force, and when inner structure can expand the performance demand that supplies the medical component to pass when bearing expansion external force, also provide obvious facility for the concrete operation of interior sleeve pipe embedding outer tube in the manufacturing process, can show the production manufacturing efficiency who promotes the pipe sheath.

Other advantages of the present invention will be described in the detailed description, and those skilled in the art can understand the technical advantages brought by the technical features and technical solutions through the descriptions of the technical features and the technical solutions.

Drawings

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the figure:

FIG. 1 is a schematic perspective view of a preferred embodiment of an interventional medical device provided by the present invention;

FIG. 2 is a schematic cross-sectional view of a preferred embodiment of an expandable catheter sheath of the present invention in an initial state;

fig. 3 is a schematic cross-sectional view of a preferred embodiment of the inner sleeve according to the present invention in an initial state;

fig. 4 is a schematic cross-sectional view of a preferred embodiment of the inner sleeve in a fully expanded state according to the present invention;

fig. 5 is a schematic side view of a preferred embodiment of an axial protrusion according to the present invention.

The reference numbers indicate:

reference numerals	Name (R)	Reference numerals	Name(s)	Reference numerals	Name (R)
						10	Expandable catheter sheath	212	First groove edge	224	Second fold line
20	Interventional medical device	213	Second groove edge	110	Diameter variable part
						100	Outer sleeve	220	Inner layer structure	300	Axial projection
200	Inner sleeve	221	First folding wing	310	Equal diameter extension part
						210	Outer layer structure	222	Second folded wing	320	Narrowing part
211	Notch groove	223	First fold	330	Pre-tearing groove

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth, such that well-known methods, procedures, flows, and components have not been described in detail so as not to obscure the present invention.

Furthermore, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Description of the drawings: the utility model discloses use the pipe sheath under the user state, advance into the internal one end of patient for preceding, the other end is the back.

In a first aspect, referring to fig. 1-5, the present invention provides an expandable catheter sheath 10, comprising an outer sheath 100 and an inner sheath 200 nested together, the outer sheath 100 being resilient to apply a radially inward gripping force to the inner sheath 200, the inner sheath 200 comprising an outer structure 210 and an inner structure 220; the outer layer structure 210 has a notch groove 211 arranged along the axial direction, so that the cross section of the outer layer structure 210 is in a circular arc shape that is not closed in the circumferential direction; the inner layer structure 220 is a flexible structure and is in a cylindrical shape with a closed circumferential direction, and the inner wall of the outer layer structure 210 is attached and connected with a part of the outer wall of the inner layer structure 220;

referring to fig. 2-3, the outer sleeve 100 has a minimum diameter when the dilatation catheter sheath is not subjected to an external force for dilatation; the first and second slot edges 212 and 213 of the relief slot 211 of the outer layer structure 210 are close to each other, making the diameter of the outer layer structure 210 smaller; the inner layer 220 is folded at a portion corresponding to the notch groove 211 at a radially inner side to form a first folding wing 221 and a second folding wing 222 which are symmetrical;

referring to fig. 4, when the dilatation catheter sheath is subjected to an external expansion force, the first slot edge 212 and the second slot edge 213 of the notch slot 211 of the outer layer structure 210 are separated from each other, so that the diameter of the outer layer structure 210 is enlarged, the first folding wing 221 and the second folding wing 222 of the inner layer structure 220 are at least partially unfolded, and the outer sleeve 100 is elastically deformed to be enlarged.

For the expandable catheter sheath 10 provided by the present invention, when no medical component passes through, the expandable catheter sheath 10 is in an initial state without being subjected to external expansion force, in this initial state, the inner sleeve 200 is in a state where the inner layer structure 220 is folded radially inward to form the first folding wing 221 and the second folding wing 222 that are symmetrical, and the diameter of the outer sleeve 100 is the minimum, that is, the entire expandable catheter sheath 10 is in a state of the minimum outer diameter, so as to be convenient for entering the patient body at the initial stage of the operation; when a medical component with a relatively large radial dimension passes through the expandable catheter sheath 10, the inner structure 220 in the inner sleeve 200 is acted by an external expansion force, the first folding wings 221 and the second folding wings 222 are at least partially unfolded and even completely unfolded, and the diameters of the outer structure 210 in the inner sleeve 200 and the outer sleeve 100 are increased, so that the medical component can pass through the expandable catheter sheath 10 smoothly; after the medical components pass through the catheter sheath 10, the catheter sheath 10 is no longer subjected to external expansion force, the elastic property of the outer sheath 100 can drive the inner sheath 200 to restore the initial state when the external expansion force is not applied, and the catheter sheath 10 returns to the state of minimum outer diameter, so that the catheter sheath 10 can be conveniently taken out of the human body.

Specifically, the outer sleeve 100 is a single-lumen tube with elasticity, the cross section of the outer sleeve 100 is generally regular and circular, the outer sleeve 100 can apply a radially inward tightening force to the inner sleeve 200, and the outer sleeve 100 has the elastic characteristic that after the medical assembly enters the inner sleeve 200 to expand the inner sleeve 200, the outer shape of the catheter sheath 10 is still a regular structure under the protection of the outer sleeve 100, so that vascular complications and blood leakage caused by local irregularity of the outer contour of the catheter sheath are effectively avoided. In one example, the outer structure 210 has a hardness greater than the hardness of the inner structure 220 and also greater than the hardness of the outer sleeve 100 to provide good support for the outer sleeve 100 and the inner structure 220.

The outer layer structure 210 of the inner sleeve 200 has a notch groove 211 arranged along the axial direction, so that the cross section of the outer layer structure 210 is in a circular arc shape which is not closed in the circumferential direction, and the arrangement of the notch groove 211 facilitates the folding of the corresponding portion of the inner layer structure 220 to form two folding wings.

The number of the folding wings is two (i.e. the first folding wing and the second folding wing), which can further increase the folding degree of the inner layer structure 220 compared to that of only a single folding wing, so that the difference between the inner diameters of the two cases of the initial state and the fully unfolded state is larger, and a larger size medical assembly can pass through the inner layer structure, in one example, the inner diameter of the inner layer structure 220 of the inner cannula 200 in the initial state without bearing external force for expansion is 14F-20F, and the inner diameter of the inner layer structure 220 can be larger than that of the initial state by 8F-18F when the first folding wing and the second folding wing are fully unfolded; further, the first folding wing 221 and the second folding wing 222 are symmetrical, which is more convenient to design and manufacture than when they are not symmetrical.

The inner layer structure 220 is folded at the radial inner side corresponding to the position of the notch groove 211, that is, the first folding wing 221 and the second folding wing 222 are formed inside the inner layer structure, so that the outer profile of the inner sleeve 200 is basically regular and does not bulge outwards, the outer diameter of the catheter sheath is relatively smaller when the outer sleeve is not subjected to expansion external force, and the inner layer structure can expand to meet the service performance requirement for passing medical components when the inner sleeve 200 is subjected to expansion external force, and meanwhile, the inner sleeve 200 is embedded into the outer sleeve 100 in the manufacturing process, so that obvious convenience is provided, and the production and manufacturing efficiency of the catheter sheath can be obviously improved.

Preferably, referring to fig. 3, the inner layer structure 220 is provided with one first crease 223 at each of the positions of the first groove edge 212 and the second groove edge 213, and two second creases 224 are further provided between the two first creases 223.

Specifically, in order to facilitate the smooth inward folding of the portion of the inner layer 220 corresponding to the notch groove 211 into the first folding wing 221 and the second folding wing 222, the inner layer 220 is provided with a first folding line 223 at the position of the first groove edge 212, and the inner layer 220 is folded inward along the first folding line 223, where the first folding line is the starting end of the first folding wing 221; the inner layer 220 is also provided with a first folding line 223 at the position of the second slot edge 213, along which the inner layer 220 is folded inwards, and the first folding line is the starting end of the second folding wing 222; two second folding creases 224 are formed between the two first folding creases 223, the first folding wing 221 is turned again at the second folding crease 224 relatively closer to the first groove edge 212, and the second folding wing 222 is turned again at the second folding crease 224 relatively closer to the second groove edge 213, so that the first folding wing 221 and the second folding wing 222 are formed, the starting ends of which are respectively at different first folding creases and the tail ends of which are integrally connected.

Preferably, referring to fig. 1, the inner sleeve 200 has an overall length of 320-400mm, and in an initial state before the catheter sheath is expanded, the inner sleeve 200 extends from the rear end surface thereof by a length of 40-110mm, and the folding degree of the inner structure 220 is gradually increased, so that the outer diameter of the inner sleeve is gradually decreased.

In order to guide the medical assembly with larger outer diameter to smoothly enter the catheter sheath 10 in the initial state, the utility model discloses in the range that the length is 40-110mm from the rear end face of interior sleeve pipe 200 extends forward, the degree of inward folding of inner layer structure 220 in interior sleeve pipe 200 is bigger and bigger (the part of inward folding is longer and longer), make the rear end face department of interior sleeve pipe 200 because the minimum diameter of the minimum event diameter of folding degree that inner layer structure here is the biggest from this, and after this extension is length 40-110 mm's transition portion, the inward folding degree of inner layer structure 220 in interior sleeve pipe 200 no longer changes, the diameter of interior sleeve pipe 200 no longer continues to diminish, can realize leading the medical assembly with larger outer diameter smoothly to enter the inside purpose of interior sleeve pipe.

Preferably, the rear end surface of the outer sleeve 100 is flush with the rear end surface of the inner sleeve 200, and the outer sleeve 100 covers at least the portion of the inner sleeve with the gradually decreasing outer diameter to form an outer sleeve with at least a reducing portion 110.

Referring to fig. 1, in order to fully ensure that the outer sleeve 100 can bring the inner sleeve 200 to the initial state when not subjected to the external expansion force after the medical assembly passes through the catheter sheath 10, the outer sleeve covers at least a portion of the inner sleeve with a gradually decreasing outer diameter to form an outer sleeve with at least a reducing portion 110.

In one example, the outer sleeve 100 covers the entire length of the inner sleeve 200, thereby further increasing the speed at which the inner sleeve 200 is carried by the outer sleeve 100 after the medical assembly passes through the catheter sheath 10.

The diameter at the smallest diameter and the diameter at the largest diameter of the inner jacket tube at the rear end may be 5-7mm, where "smallest diameter" and "largest diameter" are both directed towards the outer diameter of the outer structure in the rear end of the inner jacket tube.

Preferably, referring to fig. 1 and 5, the front end of the catheter sheath is provided with an axial protruding part 300, the axial protruding part 300 comprises an equal-diameter extending part 310 and a narrowed part 320 which are integrally connected, the narrowed part 320 is located at the front end of the equal-diameter extending part 310, the outer contour of the narrowed part 320 is in a truncated cone shape, the axial protruding part 300 is provided with at least one pre-tearing groove 330, and the pre-tearing groove 330 extends from the equal-diameter extending part 310 to the narrowed part 320 but does not penetrate through the front end of the narrowed part 320; under the action of the expanding external force, the front end portion of the tapered portion 320 can be torn through to the front end along the pre-tearing groove 330.

Specifically, in order to facilitate the entry of the sheath 10 into the body, the head at the forward end of the sheath is typically tapered, which may allow medical components to become lodged therein and not pass easily.

On one hand, the utility model, in consideration of the requirement of facilitating the smooth entering of the catheter sheath 10 into the human body, is provided with the axial protruding part 300 comprising the equal-diameter extending part 310 and the narrowing part 320 at the front end of the catheter sheath, and the narrowing part 320 can be fixed on the catheter sheath 10 through the equal-diameter extending part 310; on the other hand, in order to prevent the medical component from being stuck by the arrangement of the narrowing portion 320, at least one pre-tearing groove 330 which does not penetrate through the front end of the narrowing portion 320 is arranged on the axial protruding portion 300, when the medical component passes through, the gap of the pre-tearing groove 330 is larger as the groove gap is larger under the action of the expanding external force, and finally the pre-tearing groove can be torn and penetrated through the front end of the narrowing portion 320, so that the medical component can smoothly pass through the head of the catheter sheath.

Preferably, the front end of the outer layer structure 210 is located inside the constant diameter extension 310, and the constant diameter extension 310 is fixedly connected with the front end of the outer layer structure 210 by welding.

Specifically, making the axial protrusion 300 a separate component from the inner sleeve 200 and the outer sleeve 100, rather than manufacturing the axial protrusion with a layer of the inner sleeve 200 or the front end of the outer sleeve, facilitates the manufacturing process and separate selection of materials for manufacturing the axial protrusion 300 including the constant diameter extension 310 and the tapered portion 320. It will be appreciated by those skilled in the art that in order to allow the tapered portion 320 to be easily torn, the relatively independent axial protrusion 300 may be made of a relatively brittle, non-crumbly material (rather than being made of the same material as the inner structure 220, the outer structure 210, or the outer sleeve 100) while meeting the strength requirements, such that the tapered portion 320 will crack with a small amount of force and allow medical components to pass through more easily.

The equal-diameter extension part 310 in the axial protrusion part 300 is fixedly connected with the front end of the inner layer structure 220 through welding, and the axial protrusion part 300 and the inner layer structure 220 can be fixedly connected through a simple and convenient operation process and are not easy to fall off.

Preferably, the number of the pre-tearing grooves 330 is one, and the position of the pre-tearing groove 330 in the circumferential direction corresponds to the notch groove 211 of the outer layer structure 210.

Specifically, only one pre-tearing groove 330 is provided, so that when the medical assembly passes through the axial protrusion 300, an expansion external force is concentrated on the only obvious weak point of the pre-tearing groove, and under the condition of a small external force, the groove gap of the pre-tearing groove 330 can be rapidly expanded, so that the front end part of the narrowing part 320 is torn to penetrate through the front end of the narrowing part, and the medical member can rapidly and smoothly pass through the head part of the catheter sheath. The circumferential position of the pre-tearing groove 330 corresponds to the notch groove 211 of the outer layer structure 210, so that when the medical assembly reaches the front end of the catheter sheath, the gap of the pre-tearing groove 330 is immediately driven to expand, and the medical assembly can smoothly enter the axial protrusion 300.

Preferably, each fold is parallel to each other, and the portion of each pre-tear groove 330 on the constant diameter extension 310 is parallel to the first fold 223.

Specifically, in order to facilitate the manufacture of the symmetrical first folding wing 221 and the second folding wing 222, each of the folds may be parallel to each other, that is, any two of the first folds 223 and the second folds 224 are parallel to each other. The part of the pre-tearing groove 330 on the equal-diameter extension part 310 is parallel to the first fold 223, that is, parallel to any fold, which facilitates the manufacturing of the pre-tearing groove 330, and also makes the pre-tearing groove 330 more easily expandable under the external force of expansion, so that the front end part of the tapered part 320 is torn through to the front end of the tapered part, which facilitates the passing of the medical assembly.

Preferably, the surface of the outer sleeve 100 has a hydrophilic coating; the wall thickness of the outer sleeve 100 is 0.05-0.5mm.

In particular, the outer sleeve may be coated with a hydrophilic coating on its surface to reduce resistance to entry into the body's blood vessels, which in one example may be PVP (polyvinylpyrrolidone). The wall thickness of the outer sleeve 100 can be selected to be 0.05-0.5mm according to the actual use performance requirements such as strength.

In one example, the inner layer structure 220 may be made of PE (polyethylene) or PTFE (polytetrafluoroethylene); the outer structure 210 may be made of PE, PEBAX (polyether block polyamide) or PVC (polyvinyl chloride); the outer sleeve 100 may be made of one of fluororubber, PU (polyurethane) and silicone.

In a second aspect, referring to fig. 1, there is also provided an interventional medical device 20 comprising an introducer sheath 10 as described above.

It will be appreciated by those skilled in the art that the above-described preferred embodiments may be freely combined, superimposed, without conflict.

It will be understood that the above-described embodiments are illustrative only and not restrictive, and that various obvious and equivalent modifications and substitutions may be made in the details described herein by those skilled in the art without departing from the basic principles of the invention.

Claims (10)

1. An expandable catheter sheath (10), characterized by: comprises an outer sleeve (100) and an inner sleeve (200) which are arranged in a nesting way, wherein the outer sleeve (100) has elasticity so as to apply a radially inward clamping force to the inner sleeve (200),

the inner casing (200) comprises an outer layer structure (210) and an inner layer structure (220); the outer layer structure (210) is provided with a notch groove (211) arranged along the axial direction, so that the cross section of the outer layer structure (210) is in a circular arc shape which is not closed in the circumferential direction; the inner layer structure (220) is a flexible structure and is in a cylinder shape with the circumferential direction being closed, and the inner wall of the outer layer structure (210) is attached and connected with one part of the outer wall of the inner layer structure (220);

the outer sleeve (100) has a minimum diameter when the dilatation catheter sheath is not subjected to an external dilatation force; the first and second slot sides (212, 213) of the relief slot (211) of the outer layer structure (210) are adjacent to each other, reducing the diameter of the outer layer structure (210); the part of the inner layer structure (220) corresponding to the notch groove (211) is folded at the radial inner side to form a first folding wing (221) and a second folding wing (222) which are symmetrical;

when the expanding catheter sheath is subjected to an external expanding force, the first groove edge (212) and the second groove edge (213) of the notch groove (211) of the outer layer structure (210) are separated from each other, so that the diameter of the outer layer structure (210) is increased, the first folding wing (221) and the second folding wing (222) of the inner layer structure (220) are at least partially unfolded, and the outer sleeve (100) is elastically deformed and increased in diameter.

2. The catheter sheath according to claim 1, characterized in that the inner layer (220) is provided with one first fold (223) at each of the positions of the first groove edge (212) and the second groove edge (213), and two second folds (224) are further provided between the two first folds (223).

3. The catheter sheath according to claim 1, characterized in that the inner sleeve (200) has an overall length of 320-400mm, and in an initial state of the catheter sheath before expansion, the inner sleeve (200) extends from a rear end surface thereof by a length of 40-110mm, and the degree of folding of the inner layer structure (220) is gradually increased, so that the outer diameter of the inner sleeve is gradually decreased.

4. The catheter sheath according to claim 3, characterized in that the rear end face of the outer sleeve (100) is flush with the rear end face of the inner sleeve (200), and the outer sleeve (100) covers at least the portion of the inner sleeve with the gradually decreasing outer diameter to form an outer sleeve with at least a reducing portion (110).

5. The catheter sheath according to claim 2, characterized in that the front end of the catheter sheath is provided with an axial protrusion part (300), the axial protrusion part (300) comprises an equal-diameter extension part (310) and a narrowing part (320) which are integrally connected, the narrowing part (320) is positioned at the front end of the equal-diameter extension part (310), the outline of the narrowing part (320) is in a frustum cone shape, the axial protrusion part (300) is provided with at least one pre-tearing groove (330), and the pre-tearing groove (330) extends from the equal-diameter extension part (310) to the narrowing part (320) but does not penetrate through the front end of the narrowing part (320); under the action of the external force of expansion, the front end part of the narrowing part (320) can be torn to penetrate through to the front end along the pre-tearing groove (330).

6. The catheter sheath according to claim 5, characterized in that the front end of the outer structure (210) is located inside the constant diameter extension (310), the constant diameter extension (310) being fixedly connected to the front end of the outer structure (210) by welding.

7. The catheter sheath according to claim 6, wherein the pre-tear groove (330) is one in number, and the position of the pre-tear groove (330) in the circumferential direction corresponds to the notch groove (211) of the outer layer structure (210).

8. The introducer sheath according to claim 5, wherein each of the folds are parallel to each other, and the portion of each pre-slit groove (330) on the constant diameter extension (310) is parallel to the first fold (223).

9. The introducer sheath according to claim 1, wherein the outer sleeve (100) has a hydrophilic coating on its surface; the wall thickness of the outer sleeve (100) is 0.05-0.5mm.

10. An interventional medical device (20) comprising a catheter sheath (10) according to any one of claims 1-9.

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