WO2003022347A1

WO2003022347A1 - Endoprosthesis

Info

Publication number: WO2003022347A1
Application number: PCT/KR2002/001708
Authority: WO
Inventors: Soo-Won Suh; Jhin-Gook Kim; Ho-Joong Kim; Jae-Seung Jeong
Original assignee: Tno Co., Ltd.
Priority date: 2001-09-12
Filing date: 2002-09-11
Publication date: 2003-03-20
Also published as: CN1564700A; CN100337701C; KR20030023171A; KR100439022B1

Abstract

The present invention is to provide an endoprosthesis, generally called a stent, that is designed to be firmly fixed into patient's body lumen regardless of the change of configuration of a body lumen such as an airway, thereby improving its stability and increasing its durability by flexibly and increasing its durability by flexibly corresponding to the operating state of the body lumen such as the airway.

Description

ENDOPROSTHESIS

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to an endoprosthesis, generally called a stent, and more particularly, to a stent that is designed to be firmly fixed into patient's body lumen regardless of the change of configuration of a body lumen such as an airway, thereby improving its stability and increasing its durability by flexibly corresponding to the operating state of the body lumen such as the airway. (b) Description of the Related Art

Generally, body lumen stenosis such as airway stenosis can generally be divided into intraluminal obstruction, extrinsic compression and malacia according to anatomically damaged segments. An endoprosthesis that is, a stent for expanding the narrowed passage of the body lumen such as an airway has been used to treat patients' dyspnea due to extrinsic compression and malacia of airway stenosis.

This type of stents generally has a cylindrical structure and is made from a metal and/or a silicone rubber in a type of mesh. Generally, a self-expandable stent that is constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces has been widely used. Such stents are inserted into the narrowed region of a body lumen by using a stent inserting device.

In order to function properly, the self-expandable stent has to possess some properties, for example, the expansibility for expanding the body lumen with a predetermined force, the applicability for being flexibly flexed according to the bent configuration of the body lumen, the stability for being fixed to the position inserted into the body lumen, and the contractibility for being contracted below a predetermined size. An exemplary metal self-expandable stents are disclosed in

Giantruco U.S. Pat. No. 4,580,568 and Wallsten U.S. Pat. No. 4,655,771 .

The metal self-expandable stents such as the Giantruco stent and the Wallsten stent can easily be inserted into the body lumen such as an airway, and may expand the body lumen further without requiring the anesthetizing of the patient. However, because of the difficulty in repositioning the metal stents within the narrowed region of the body lumen or removing it from the narrowed region, the metal stents are mostly used in malignant airway obstruction. That is, although there is the advantage of the metal self-expandable stents being able to be easily inserted into the narrowed region of the body lumen because of the decreasing diameter

of an inserting device, the metal self-expandable stents posses the essential disadvantage where a re-stenosis takes place because of the tissues growing between the metal filaments of the stents.

In order to solve this problem, the metal stents are coated with a polymer material, thereby preventing the tissue from growing therein. Accordingly, re-stenosis of the body lumen can be prevented and the metal stents can be inserted into the narrowed region of the body lumen easily and securely. However, the metal stents still have the disadvantage of easily moving around because of not being able to be firmly fixed into the body lumen such as an airway. That is, in order to prevent re-stenosis of the body lumen due to growing of the tissue inside the stents, there is a need of coating the metal stents with a polymer material. However, in such a case, the stents easily move away from the narrowed region of the body lumen, thereby the original objective, which was to prevent stenosis of the body lumen, cannot be fulfilled.

Furthermore, since most of silicone stents simply have a cylindrical structure, such stents have difficulty in being inserted within the body lumen such as airway because of its large size and being fixed into the body lumen firmly, thus greatly decreasing their stability. Also, because of this simple coaxial cylindrical structure with self-expandable property, the stent for expanding the narrowed passage of the body lumen does not flexibly correspond to the change of configuration of the airway where such configuration greatly changes with airway stenosis from patient's coughing and so on, thereby greatly decreasing its durability.

That is, when the airway greatly changes with stenosis patient's coughing, the section shape of the stent is not folded in a C-shape having the same curvature center as that of the stent in changing configuration of the airway. The portion of which the stent is not folded, acts against the changing forces of configuration of the airway, thereby coming under a great stress and resulting into an easy breakage of the stent. Accordingly, the durability of the stent is greatly decreased.

SUMMARY OF THE INVENTION

Therefore, the present invention has been conceived in an effort to solve the above-described problems of the conventional stents.

It is an objective of the present invention to provide an endoprosthesis, generally called a stent, that is designed to be firmly fixed into patient's body lumen regardless of the change of configuration of a body lumen such as an airway, thereby improving its stability and increasing its durability by flexibly corresponding to the operating state of the body lumen such as the airway. To achieve the above objectives, one embodiment of the present invention provides a stent comprising a main body that is constricted under external forces and takes an expanded position by

itself when it is left in an unloaded condition free of the external forces, the main body having a predetermined length and shape, and a flexible portion for forming a passage therein together with the main body by connecting the both ends of the main body with each other and accommodating flexibly the main body to the change of configuration of a body lumen such as an airway. The stent may comprise a plurality of fixing portions for firmly fixing the main body to the narrowed region of a body lumen such as an airway, the fixing portions being formed on the outer surface of the main body. The stent may comprise a connecting portion for connecting one stent to the other stent and retaining its properties and without having further process, apparatus, and operation, the connecting portion being formed in a predetermined size at the end of the stent.

With this structure, when the stent according to an embodiment of the present invention is inserted into the narrowed region of the body lumen such as a airway, the self-expandability of its main body expands the narrowed region of the airway, the passage between the interior of main body and the flexible portion is used as a passage of the airway, and the fixing portion firmly fixes the stent in the narrowed region of the airway. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a stent according to a first embodiment of the present invention;

FIG. 2 is a longitudinal section view of a stent according to a first embodiment of the present invention;

FIG. 3 is a perspective view of a stent in the folded state according to a first embodiment of the present invention;

FIG. 4 is a longitudinal section view of a stent shown in FIG. 3. FIG. 5 is a cross section view of a stent in a coupled state according to a first embodiment of the present invention;

FIG. 6 is an enlarged view of an "A" portion shown in FIG. 5; FIG. 7 is a perspective view of a stent according to a second embodiment of the present invention; FIG. 8 is a longitudinal section view of a stent according to a second embodiment of the present invention; and

FIG. 9 is a side view of a stent according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described hereinafter in more detail in conjunction with accompanying drawings.

Referring to FIGS. 1 to 6, a stent 10 according to a first embodiment of the present invention comprises a main body 1 1 which has a predetermined length and shape and may be constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces, and a flexible portion 13 for connecting the both ends of the main body 1 1 with each other and forming a passage therein together with the main body 1 1 .

The flexible portion 13 retaining its predetermined flexibility may flex the main body according to the change of configuration of the body lumen, for example, an airway. The main body 1 1 may be formed in a half cylindrical structure corresponding to the flexible portion as shown FIG. 1. However, the present invention is not limited to this. That is, the main body 1 1 may be formed in another structure such as a cylindrical structure.

The stent 10 comprises a plurality of fixing portions 15 which are formed on the outer surface of the main body 1 1 . The fixing portions firmly fix the main body 1 1 to the narrowed region of the body lumen such as the airway.

Furthermore, the stent 10 comprises a connecting portion for connecting one stent to the other stent so that it may be used for a long narrowed region or a bent region of the body lumen such as the airway. The connecting portion is formed in a predetermined size at the end of the stent 10. The connecting portion connects at least one stent while retaining its properties and without having further process, devices, and operation. The cross section of the main body 11 can be formed closely to a semicircular shape or circular shape; preferably, it is formed in C-shaped structure so that the flexible portion may be folded easily when configuration of the body lumen such as the airway is changed. Furthermore, preferably the main body 11 is made from materials having self-expandable property and a predetermined profile such as silicon, rubber, and polymer. Preferably, the main body 1 1 should have a flexibility in order to efficiently adapt to the narrowed region of the bent body lumen. Preferably, the main body 1 1 should also have a contractibility in order to be constricted below a predetermined size to be inserted into the narrowed region of the body lumen such as the airway

Preferably, the main body 1 1 should have a predetermined flexibility so that it may be efficiently folded by the operation of the flexible portion.

Preferably, the flexible portion 13 is mostly formed in flat-plane shape, it is contractible and expandable by itself together with the main body 1 1 in order to easily insert the stent into the body lumen, and it is integrally made from the same materials as the main body 11 .

In addition, the flexible portion 13 may be integrally formed with the main body 1 1 ; it can be formed to have the same thickness as the main body 1 1 or different thickness from the main body.

Preferably, the flexible portion 13 has the flexibility greater than that of the main body 11 so that it may be flexibly adapted, that is, folded according to the change of configuration of the airway. More preferably, the flexible portion 13 is formed below the thickness of the main body 1 1 . Furthermore, the flexible portion 13 can be formed to have the uniform or different thickness along its width. Preferably, the thickness of the flexible portion 13 gets smaller as it inwardly approaches in the longitudinal direction of the center line so that it may be easily folded according to the change of configuration of the body lumen.

Preferably, the flexible portion 13 is formed to be folded with the same radius center as that of the main body 1 1 when it is folded according to the change of configuration of the body lumen. Preferably, the fixing portions 15 are formed to have stiffness and are not crushed when an external force is applied to the main body 1 1 and the flexible portion 13 of the stent 10, and they restores to original shape of the stent 10 when the external force is removed.

Preferably, the fixing portions 15 may be integrally formed with the main body and they are made from the same materials as the main body and flexible portion.

Furthermore, the fixing portions 15 may be formed to protrude from the entire or a part of circumferential surface along the circumferential direction of the main body in order to firmly fix the main body 11 to the narrowed region of the body lumen.

The fixing portions 15 may be formed to have the same radius center as the main body 11 in order to flexibly correspond to the change of configuration of the body lumen together with the main body 1 1 . The section of the fixing portions 15 has a predetermined shape; preferably, it can be formed in a rectangular shape in order to fix the main body 11 more firmly.

And then, the fixing portions 15 may be formed in a uniform or any distance along the longitudinal direction in the outer surface of the main body 1 1 , and they can also be formed in a uniform or any distance along the radial direction in the outer surface of the main body 1 1 .

The fixing portions 15 can also be formed to protrude to the same height as that of the outer surface of the main body 11 , and then they may be formed to protrude a different height from that of the outer surface of the main body 1 1 .

Preferably, a space region 200 is formed between the fixing portions 15 in order to secure the main body more firmly to the body lumen with a tissue penetrating the main body 1 1 when the main body 11 is inserted into the narrowed region of the body lumen such as the airway.

Furthermore, the connecting portion is formed on an end portion and the other end portion of the stent. The connecting portion comprises female and male connecting elements 17, 18, 19 and 20 for connecting one end portion and the other end portion of a stent to the other end portion and an end portion of other stents, respectively.

When the narrowed region of the body lumen such as the airway is long, the connecting portion may be used to connect a plurality of stents along the length of the narrowed region.

Preferably, the connecting portion is made from materials having a flexibility for efficiently adapting to the degree of bending of the body lumen when it is inserted into the bent region in the narrowed region of the body lumen such as the airway. Preferably, the connecting portion is integrally made from the same materials as the main body and the flexible portion.

Preferably, the female and male connecting elements 17, 18, 19 and 20 are formed from materials having a predetermined shape and self-expansibility in order to easily connect to each other.

The female connecting elements 17 and 18 and the male connecting elements 19 and 20 are formed at one end portion and the other end portion of the main body 1 1 and the flexible portion 13 of the stent 10 respectively. And then, preferably, the inside diameters of the male connecting elements 19 and 20 are formed with the substantially same diameters as that of the main body 1 1 and the flexible portion 13 in order to firmly fit the stents, and the outside diameters of the female connecting elements 17 and 18 are formed with the substantially same diameters as that of the outside -diameters of the male connecting elements 19 and 20 in order to firmly fit the stents.

Furthermore, the inner surface of the female connecting elements 17 is provided with a stopper 23 for stopping the female connecting elements 17 to the end of the male connecting elements 19 to prevent the male connecting elements 19 from moving to the inner side of the female connecting elements 17 in a coupled state, which the male connecting elements 19 of the other stent is coupled into the female connecting elements 17.

The stopper 23 is protruded from the inner surface to its inner side along the one end of the inner surface of the female connecting elements 17. Preferably, the stopper 23 is integrally formed with the main body 1 1 . The inner surface of the female connecting elements 18 and the outer surface of the male connecting elements 20 are provided with coupling grooves 25 and 27 for coupling the male and female connecting elements 20 and 19 to the female and male connecting elements 18 and 20 respectively in a coupled state, which the female and male connecting elements 18 and 20 are coupled to each other. The coupling grooves 25 and 27 are concaved with a predetermined size.

Preferably, the coupling groove 25 has a step forming from the inner surface of the female connecting element 18 to its outer direction and having a predetermined thickness. Preferably, the coupling groove 27 has a step forming from the outer surface of the male connecting element 20 to its inner direction and having a predetermined thickness. As such, the stent 10 of the first embodiment of the present invention is inserted into the narrowed region of the body lumen such as the airway with using a stent inserting apparatus. And then, the narrowed region of the airway is expanded by the self-expansion of the main body 1 1 of the stent 10. Therefore, when the main body 1 1 is positioned at the narrowed region of the airway, a passage 100 is formed inside the main body 1 1 and the flexible portion 13 serves as the passage of the airway.

And then, by the fixing portions 15, the main body 1 1 is firmly ' fixed to the narrowed region. That is, since the fixing portion 15 is protruded from the outer side of the main body 1 1 to its outer direction in a uniform distance, the stent 10 is firmly fixed to the narrowed region of the airway by compressing tightly the narrowed region of the airway with the protrusion region of the fixing portion 15. As such, the stent 10 is used at a fixed state, which the main body 1 1 is fixed by the fixing portion 15. And then, when tissue of the airway grows, the growing tissue penetrates into the space portion 200 formed between the fixing portions 15, thereby firmly fixing the fixing portions 15 to the narrowed region of the airway. Since the passage 100 is entirely isolated from the outer surface of the stent 10, it prevents tissue of the airway from penetrating into the stent 10.

As described above, in the fixed state, when configuration of the airway is changed with airway stenosis patient severely coughing, the flexible portion 13 is folded into an inner side of the main body 11 according to the change of configuration of the airway with a predetermined center of curvature as shown in FIG. 4 When the flexible portion 13 is folded as such, the outer surface of the main body 11 is usually folded in an elliptical shape so that the main body 11 forms the outer surface of the flexible portion 13 with a predetermined center of curvature.

According to the stent of the present invention, even if configuration of the airway is changed, the main body 1 1 may be folded flexibly according to configuration of the airway by the flexible portion 13, thereby a stress based on the force of the change of configuration of the airway is not applied to the main body 1 1. Thus, the durability of the stent 10 is improved. Also, in case the stent of the present invention is needed to be used in the long region and the bent region of the narrowed region of the body lumen such as the airway, a plurality of stents 10 can be connected by the connecting portions in the case of need.

In below, the connecting process of two or three stents will be described in detail to give an example of the connecting process. However, more number of stents can be connected using the same process.

That is, as shown in FIGS. 5 and 6, the male connecting elements 19 and 20 of the other stent 10 are fitted into the inner side of the female connecting elements 17 and 18 of one stent 10, the end portion of the male connecting element 19 is stopped at the stopper 23 of the female connecting element 18, and then the male connecting element 20 is coupled to the connecting groove 25 and the female connecting element 18 is coupled to the connecting groove 27 of the male connecting element 20.

If so, as shown in FIG.6, the end portion of the female connecting element 17 of the connecting portion contacts closely with the end portion of the fixing portions 15, and the end portion of the male connecting element 19 contacts closely with the end portion of the inner side of the female connecting elements 17 and 18, i.e. the stopper 23 and the connecting groove 15. Thus, one stent 10 is firmly fitted into and connected to the other stent 10. In the connected state as such, in need of making the stent 10 longer, the male connecting elements 19, 20 of one stent 10 fit into and connect to the female connecting elements 17, 18 of another stent 10 in the same way as described above.

Furthermore, when a plurality of stents 10 connected as such are inserted into the bent and narrowed region of the body lumen such as the airway and the connecting portions of the stents 10 are positioned at the bent region of the body lumen, the stents 10 are efficiently folded according to the degree of bending by the flexibility of the connecting region of the female and male connecting elements 17, 18, 19 and 20 of the connecting portion.

FIGS. 7 to 9 show a stent according to a second embodiment of the present invention, which is substantially similar to the first embodiment except for the following features.

The stent 10 according to the second embodiment comprises a main body 11 , a flexible portion 13, and fixing portions.

The stent 10 comprises fixing lugs 21 for firmly fixing the main body 1 1 together with the fixing portions to the narrowed region of the body lumen. The fixing lugs 21 having a predetermined shape and size are protruded from the outer surface of the fixing portions in its outer direction.

The fixing lugs 21 may be formed in the outer surface of the fixing portions 15 with a uniform or optional interval, and then in a circle, elliptic, and square shape and the like.

Moreover, the fixing lugs 21 may be formed on the outer surface of the main body along its longitudinal direction with a uniform interval and a zigzag type in order to firmly fix the main body to the body lumen as shown in FIG. 7. It will be apparent to those skilled in the art that various modifications and variations can be made to the apparatus of the present invention without departing from the scope of the invention. The present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS :

1. A stent comprising: a main body that is constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces, the main body having a predetermined length and shape; and a flexible portion for forming a passage therein together with the main body by connecting the both ends of the main body to each other and accommodating flexibly the main body to the change of configuration of a body lumen such as an airway.

2. A stent comprising: a main body that is constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces, the main body having a predetermined length and shape; and a plurality of fixing portions for firmly fixing the main body to the narrowed region of a body lumen such as an airway, the fixing portions being formed on the outer surface of the main body.

3. A stent comprising; a main body that is constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces, the main body having a predetermined length and shape; a flexible portion for forming a passage therein together with the main body by connecting the both ends of the main body to each other and accommodating flexibly the main body to the change of configuration of a body lumen such as an airway; and a connecting portion for connecting one stent to the other stent and retaining its properties and without having further process, apparatus, and operation, the connecting portion being formed in a predetermined size at the end of the stent.

4. A stent of claim 1 , wherein further comprising a plurality of fixing portions for firmly fixing the main body to the narrowed region of the body lumen such as the airway, the fixing portions being formed on the outer surface of the main body.

5. A stent of claim 3, wherein further comprising a plurality of fixing portions for firmly fixing the main body to the narrowed region of the body lumen such as the airway, the fixing portions being formed on the outer surface of the main body.

6. A stent of claim 1 , wherein further comprising a connecting portion for connecting one stent to the other stent and retaining its properties and without having further process, apparatus, and operation, the connecting portion being formed in a predetermined size at the end of the stent.

7. A stent of claim 2, wherein further comprising a connecting portion for connecting one stent to the other stent and retaining its properties and without having further process, apparatus, and operation, the connecting portion being formed in a predetermined size at the end of the stent.

8. A stent of claim 2, wherein further comprising a flexible portion for forming a passage therein together with the main body by connecting the both ends of the main body to each other and accommodating flexibly the main body to the change of configuration of the body lumen such as the airway.

9. A stent of any one of claims 1 to 3, wherein the cross section of the main body is formed in semicircular shape or circular shape.

10. A stent of any one of claims 1 to 3, wherein the cross section of the main body is formed in C-shaped structure to allow easy folding of the flexible portion according to the change of configuration of airway.

1 1 . A stent of any one of claims 1 , 3 and 8, wherein the flexible portion has the same or different thickness as that of the main body.

12. A stent of any one of claims 1 , 3 and 8, wherein the flexible portion has the uniform or different thickness along its width.

13. A stent of any one of claims 1 , 3 and 8, wherein the flexible portion is formed below the thickness of the main body.

14. A stent of any one of claims 1 , 3 and 8, wherein the flexible portion is folded with the same radius center as the main body according to the change of configuration of the body lumen.

15. A stent of any one of claims 2, 4 and 5, wherein the fixing portions are protruded from the entire or a part of a circumferential surface along the circumferential direction of the main body to firmly fix the main body to the narrowed region of the body lumen.

16. A stent of any one of claims 2, 4 and 5, wherein a space region is formed between the fixing portions to secure firmly the main body to body lumen with tissue of the body lumen being penetrated when the main body is inserted into the narrowed region of the body lumen.

17. A stent of any one of claims 2, 4 and 5, further comprising fixing lugs for firmly fixing the main body together with the fixing portions to the narrowed region of the body lumen, the fixing lugs being protruded from the outer surface of the fixing portions.

18. A stent of any one of claims 3, 6 and 7, wherein the connecting portion is formed on one end and the other end of one stent, and comprises female and male connecting elements for connecting one end and the other end of the other stent respectively.

19. A stent of any one of claims 3, 6 and 7, wherein the inside diameters of the male connecting elements of the connecting portion are formed with the substantially same diameters as the main body and the flexible portion, and the inside diameters of the female connecting elements are formed with the substantially same diameters as the outside diameters of the male connecting elements.

20. A stent of any one of claims 3, 6 and 7, wherein the inner surface of the female connecting elements of the connecting portion is provided with a stopper for stopping the female connecting elements to the end of the male connecting elements to prevent the male connecting elements from moving to the inner side of the female connecting elements in a coupled state, which the male connecting elements of the other stent is coupled to the female connecting elements of one stent.

21 . A stent of any one of claims 3, 6 and 7, wherein the inner surface of the female connecting elements and the outer surface of the male connecting elements are provided with coupling grooves for coupling the male and the female connecting elements into the female and the male connecting elements respectively in a coupled state, which the female and male connecting elements are coupled to each other.