JP5767494B2 - Covered stent, stent delivery catheter, and method for manufacturing covered stent - Google Patents

Description

  The present invention relates to a covered stent, a stent delivery catheter, and a method for manufacturing a covered stent.

  In the treatment of angina pectoris or myocardial infarction, percutaneous coronary artery reconstruction surgery (PTCA) or the like is performed on the stenosis of the coronary artery. After this treatment, a metallic intravascular stent may be implanted in the coronary artery or other vessels for the purpose of preventing restenosis or applying treatment to lesions that have not been successfully expanded by PTCA. There is also.

  Intravascular stents usually have a tubular structure that can be reduced in diameter, such as a mesh or coil made of metal wires (struts), and after being inserted into a blood vessel by a catheter in a reduced diameter state, Expanded and placed to mechanically support the vessel lumen.

  However, even after placement of an intravascular stent, it has been reported that restenosis occurs due to the proliferation or thickening of the luminal tissue from the gap between the metal wires forming the stent.

  In order to solve this problem, a metal stent and a coating material such as a polymer film or a non-woven fabric are combined to cover the gap of the metal wire, and the proliferation and thickening of the luminal tissue into the stent lumen are prevented. Research and development of covered stents that can be suppressed is underway.

  For example, the covered stent disclosed in Patent Document 1 sandwiches a flexible intervening membrane that can be expanded and contracted by two stents. Then, in the stent delivery catheter to which this covered stent is attached, since the balloon bites into the mesh of the inner stent in the covered stent, the fixation to the balloon catheter is enhanced. In addition, since the living body lumen wall bites into the mesh of the outer stent in the covered stent, a serious situation such as movement of the covered stent is avoided.

Japanese Patent No. 3211156

  However, in the covered stent of Patent Document 1, the fixability between the stents is not sufficient. Therefore, in order to prevent misalignment between the inner and outer stents, the ends facing each other in both stents can be processed by welding or pressing (pressing the metals against each other by applying a pressure high enough to dent the metal surface). Combined.

  That is, in this covered stent, the intervening membrane is easily exposed to a high-temperature heat source or exposed to a harsh mechanical environment, and as a result, is easily broken or damaged.

  The present invention has been made to solve the above problems. And the objective is to provide the covered stent etc. which integrate firmly, without using the manufacturing process which produces the damage of an intervening membrane.

The covered stent includes a cylindrical first stent having a knitted structure, a cylindrical second knitted structure surrounding the outer periphery of the first stent, and from the outside of the first stent to the inside of the second stent. A cylindrical intervening film interposed therebetween. And in this covered stent, an intervening membrane winds the pleat part which arises by making membrane sides of its inner cylinder close to each other in the cylindrical circumferential direction.

  In this case, since the thickness of the intervening membrane sandwiched between the first stent and the second stent is increased by the amount of the folds wound, the first stent and the second stent are used for the production of the covered stent. And the intervening membrane other than the folds and the folds bite into the mesh in the first stent and the mesh in the second stent. As a result, a covered stent in which the first stent, the intervening membrane, and the second stent are firmly integrated is completed.

  The number of pleats is not particularly limited, and a single pleat may be formed or a plurality of pleats may be formed.

  Also, the material of the intervening film is not particularly limited. For example, the intervening membrane may be formed of a non-stretchable material having such a property that, after expansion of the first stent and the second stent in the radial direction, the circumference of the intervening membrane does not extend more than before expansion. (In addition, such an intervening film may contain a granule or a filler, and may have thermoplasticity).

  On the other hand, the intervening membrane may be formed of a stretchable material having a property of extending its peripheral length after expansion of the first stent and the second stent in the radial direction more than before expansion.

  The intervening membrane as described above may have biocompatibility or may have a drug release function.

  Further, a stent delivery catheter including the above covered stent and a balloon catheter to which the covered stent is attached can also be said to be the present invention (note that the portion where the covered stent is attached is preferably a balloon in the balloon catheter. ).

Further, in the method for manufacturing a covered stent, the covering step in which the intervening membrane is covered on the first stent, and the pleat portion generated by bringing the inner membrane surfaces of the intervening membrane closer to each other are arranged in the cylindrical circumferential direction. And a winding step to be wound.

  And in this manufacturing method of a covered stent, it is preferable that a winding process applies heat with respect to an intervening film in the atmosphere below the glass transition temperature of an intervening film.

  According to the present invention, as a result of firmly fixing the first stent, the intervening membrane, and the second stent, a covered stent with high unity is completed.

FIG. 3 is a cross-sectional view taken along line A-A ′ of FIG. 2. FIG. 3 is an enlarged perspective view of a covered stent in a stent delivery catheter. These are explanatory drawings of a stent delivery catheter. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. FIG. 10 is a cross-sectional view taken along line B-B ′ of FIG. 9. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. FIG. 14 is a cross-sectional view taken along line C-C ′ in FIG. 13. These are sectional drawings which show the manufacturing process of a covered stent. These are sectional drawings which show the manufacturing process of a covered stent. These are perspective views which show the manufacturing process of a covered stent. These are sectional drawings which show the manufacturing process of a covered stent. These are sectional drawings which show the manufacturing process of a covered stent. These are sectional drawings which show the manufacturing process of a covered stent.

[Embodiment 1]
The following describes one embodiment with reference to the drawings. For convenience, hatching, member codes, and the like may be omitted, but in such a case, other drawings are referred to. In addition, the dimensions of various members in the drawings (for example, the mesh of the stent ST) may be adjusted so as to be easy to see for convenience.

  FIG. 3 is an explanatory view showing the stent delivery catheter 49. As shown in FIG. 3, the stent delivery catheter 49 includes a covered stent 19 and a balloon catheter 39 that carries the covered stent 19.

  There are many types of balloon catheters 39. For example, an over-the-wire type as shown in FIG.

  The covered stent 19 is attached to the balloon 31 of the balloon catheter 39. As shown in FIG. 2 which is an enlarged perspective view of FIG. 3, the covered stent 19 includes a cylindrical first stent ST1, a cylindrical second stent ST2 surrounding the outer periphery of the first stent ST1, And a cylindrical intervening membrane 11 interposed between the first stent ST1 and the second stent ST2.

  For convenience, FIG. 2 and the like are illustrated by adjusting the total lengths of the first stent ST1, the second stent ST2, and the intervening membrane 11 so that the layer structure of the covered stent 19 can be easily confirmed. FIG. 1 is a cross-sectional view taken along line A-A ′ of FIG. 2 {in other words, a cross-section in the cylinder axis direction of the covered stent 19 (eg, an orthogonal cross-section). The balloon 31 is omitted in FIG. 1 for convenience}.

  Stents ST (ST1 and ST2) are, for example, cylindrical members formed into a mesh by forming a plurality of notches (openings, meshes) HL penetrating an outer surface and an inner surface of a metal tube ( Note that the metal wire generated so as to surround the mesh HL is called a strut). Then, due to the stitch structure, the stent ST expands (that is, expands in diameter) in the radial direction when pressure is applied from the inside to the outside. The inner side means the side (lumen) having the central axis in the cross section (orthogonal cross section etc.) of the stent ST in the cylinder axis direction, and the outer side means the inner side through the peripheral wall of the stent ST. Means the other side.

  Further, the notch HL in the stent ST is not particularly limited in shape, number, arrangement, etc. (that is, the design of the stent ST is not particularly limited). Further, the design of the first stent ST1 and the design of the second stent ST2 may be the same or different.

  However, the total length of the first stent ST1 is preferably shorter than the total length of the second stent ST2. Because, when the total length of the first stent ST1 is longer than the total length of the second stent ST2, the inner wall of the lumen in the body, the outer surface of the first stent ST1 extending from the end of the second stent ST2, and the outer surface The second stent ST2 and the intervening membrane 11 sandwiched between the inner wall and the inner wall of the lumen cause a depression, and blood tends to stay in the depression (that is, a place where a thrombus is likely to occur is generated). Is).

  Moreover, although the material of the stent ST includes a metal material (for example, a cobalt-based alloy or stainless steel), it is not limited to this. For example, the material of the stent ST is a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate, a cellulose polymer such as cellulose acetate or cellulose nitrate, polytetrafluoroethylene, or a tetrafluoroethylene-ethylene copolymer. It may be a polymer material such as a fluorine-containing polymer. The material of the stent ST is not limited to a metal material or a polymer material, and may be carbon fiber or ceramics.

  In short, the material of the stent ST is not particularly limited as long as it has a certain degree of elasticity and durability. In addition, the material of the first stent ST1 and the material of the second stent ST2 may be the same or different.

  However, since the stent ST is placed in the body, it is preferable that the material has biocompatibility. Further, the stent ST may have a drug release function by being coated with a drug, for example.

  The intervening film 11 is interposed between the outer side of the first stent ST1 and the inner side of the second stent ST2 in both the stents ST1 and ST2 in which the first stent ST1 is arranged on the inner side and the second stent ST2 is arranged on the outer side. It is a cylindrical film having flexibility.

  As shown in FIG. 1, the intervening film 11 has a pleated portion 11 </ b> P generated by bringing its inner surfaces 11 </ b> N close to each other (in the cylindrical intervening film 11, the inner film surfaces). Wrap in the direction.

  In this case, as shown in FIG. 1, the fold portion 11P is wound around the cylindrical intervening membrane 11, so that the interposed portion is sandwiched between the first stent ST and the second stent ST. The thickness of the film 11 increases. Then, as shown in FIG. 19 described later (also referred to as an enlarged view of FIG. 1), when the first stent ST1 and the second stent ST2 approach each other for the production of the covered stent 19, the mesh HL in the first stent ST1. And the mesh HL in the second stent ST2 are filled with the pleat 11P and the intervening film 11 other than the pleat 11P.

  As a result, the adhesion with the first stent ST1, the intervening membrane 11, and the second stent ST2 increases (in short, the covered stent 19 that is firmly integrated is completed). Therefore, in this covered stent 19, for example, it is not necessary to weld the first stent ST1 and the second stent ST2, and the manufacturing process is simplified. Moreover, when such a welding process becomes unnecessary, the malfunction (for example, damage of the intervening film 11 etc.) resulting from welding does not occur.

  There are various materials for the intervening film 11. For example, the intervening film 11 is made of a non-stretchable material (for example, nylon) having a characteristic that the circumference of the first stent ST1 and the second stent ST2 is not elongated after expansion in the radial direction than before expansion. ).

  In the case of the intervening film 11 formed of such a non-stretchable material, it is preferable that the inner peripheral length of the intervening film 11 is longer than the outer peripheral length of the first stent ST1 after diameter expansion. In such a case, when the covered stent 19 is expanded in diameter, the intervening membrane 11 is not stretched by the outer periphery where the diameter of the first stent ST1 is expanded.

  However, since the covered stent 19 is left in the body, if the intervening membrane 11 is excessively long and is bent between the first stent ST1 and the second stent ST2, due to the bending, the covered stent 19 This may disturb the blood flow in the vicinity of the lumen wall. Therefore, the inner peripheral length of the intervening film 11 may be substantially the same as the outer peripheral length of the first stent ST1 after the diameter expansion (in short, the inner peripheral length of the intervening film 11 is the diameter expanded. It may be longer than the outer perimeter of the subsequent first stent ST1).

  In addition, such a non-stretchable material may contain granules or fillers, for example, for improving biocompatibility or mechanical strength. Further, since the non-stretchable material does not stretch, it is easy to maintain the drug release function.

  On the other hand, the intervening film 11 may be formed of a stretchable material having a property of extending the circumference of the first stent ST1 and the second stent ST2 in the radial direction more than before expansion. . The intervening film 11 may be a material having thermoplasticity regardless of the non-stretchable material and the stretchable material.

  The shape of the cross section of the intervening film 11 is not limited to a circle, and may be, for example, an ellipse, a rectangle, or a polygon. Further, the thickness of the intervening film 11 is not particularly limited as long as it does not impair flexibility and does not hinder the penetration of the stent ST into the mesh HL.

  By the way, the covered stent 19 is attached to the balloon 31 in the balloon catheter 39. Then, the covered stent 19 expands in diameter as the balloon 31 expands. However, the member for expanding the diameter of the covered stent 19 is not limited to the balloon 31.

  For example, any member other than the balloon 31 may be used as long as the diameter of the covered stent 19 can be expanded by an external stimulus such as pressurization, water supply, voltage application, and heating (the covered stent 19 is attached). The member is called a base material). However, when the covered stent 19 is attached to the base material by, for example, pressure bonding, it is preferable that the base material is formed of a material that can bite into the mesh HL of the first stent ST1.

  Here, the manufacturing method of the covered stent 19 and the manufacturing method of the stent delivery catheter 49 will be described with reference to FIGS.

  First, as shown in FIG. 4, for example, a first stent ST <b> 1 that is a cylindrical body is inserted into a mandrel 51 that is parylene-coated [first stent attachment step]. FIG. 5 shows a state where the first stent ST1 covers the mandrel 51.

  Next, as shown in FIG. 6, the intervening film 11 is fitted so as to cover the first stent ST1 on the mandrel 51 [covering step]. FIG. 7 shows a state in which the intervening film 11 covers the first stent ST1.

  As shown in FIG. 7, the peripheral length of the intervening film 11 is larger than the peripheral length of the first stent ST1. Therefore, when the inner surfaces 11N of the intervening film 11 are brought close to each other, as shown in FIG. 8, a pleated portion 11P is generated (note that the pleated portion 11P includes the circumference of the intervening film 11 and the circumference of the first stent ST1. Formed by the surplus resulting from the difference between).

  Therefore, as shown in FIG. 9 and FIG. 10 (a cross-sectional view taken along line BB ′ in FIG. 9), for example, a U-shaped gripping tool 52 that sandwiches the surface of the pleat 11P is a pleat. 11P is fixed. More specifically, two pleats 11P that are opposed to each other around the first stent ST1 (the two cross-sectional circles of the first stent ST1 are separated by 180 ° from the root position so that the two wings 11 The pleat 11P) is left still in the atmosphere below the glass transition temperature of the intervening film 11 until it is sufficiently brazed while being sandwiched by the gripping tool 52 [brazing step].

  In addition, when the mandrel 51 is parylene-coated, the mandrel 51 and the intervening film 11 do not adhere to each other in the heating atmosphere in the brazing step, and the mandrel 51 does not easily come off.

  After the intervening film 11 is wrinkled, the gripping tool 52 is removed from the intervening film 11, and the pleat 11P is wound around the first stent ST1 as shown in FIG. [Winding step]).

  Further, a protective tube (not shown) is fitted so as to cover the intervening film 11 [protective tube mounting step]. Then, it is left still again in the atmosphere below the glass transition temperature of the intervening film 11 until the shape of the intervening film 11 is maintained (that is, the winding step is performed in an atmosphere below the glass transition temperature. ).

  That is, this protective tube holds the pleat portion 11P of the intervening membrane 11 in a state of being wound around the periphery of the first stent ST1. Therefore, the inner diameter of the protective tube may be a diameter that can suppress the restoration of the blade-shaped intervening film 11. The material of the protective tube is not particularly limited, but is preferably a material that can suppress friction against the intervening film 11 in consideration of workability when the protective tube is removed after brazing.

  After the shape of the intervening membrane 11 is maintained, the protective tube is removed, and the mandrel 51 inserted into the first stent ST1 is removed as shown in FIG. 12 [mandrel removal step]. Thereafter, as shown in FIG. 13, the balloon 31 in the balloon catheter 39 is inserted into the first stent ST1 [base material insertion step]. A cross-sectional view of this state is as shown in FIG. 14 (that is, FIG. 14 is a cross-sectional view taken along the line C-C ′ of FIG. 13).

  Then, as shown in FIG. 15 (the white arrow means crimping), the first stent ST1 covers the balloon 31 and the intervening membrane 11 covers the first stent ST1. Crimping is performed [first crimping step]. When such crimping is performed, as shown in FIG. 16, the intervening film 11 other than the pleat portion 11P and the pleat portion 11P bites into the mesh HL in the first stent ST1.

  Further, when the balloon 31 has a blade shape similar to that of the intervening membrane 11 and is wound in the circumferential direction of the balloon 31, the balloon 31 bites into the mesh HL of the first stent ST1 by the first crimping (that is, The adhesion between the balloon 31 and the first stent ST1 is increased).

  That is, the first crimping causes the mesh HL of the first stent ST1 to bite the intervening film 11 other than the pleat 11P and the pleat 11P, and also the balloon 31. As a result, the diameter of the first stent ST1 is reduced. The degree of adhesion between the intervening membrane 11 and the balloon 31 is increased, and they are integrated.

  Next, as shown in FIG. 17, the second stent ST2 is fitted so as to cover the intervening membrane 11 [second stent attaching step]. Thereafter, as shown in FIG. 18 (white arrows mean crimping), the second crimping is performed with the second stent ST2 covering the intervening membrane 11 [second crimping step]. When such crimping is performed, as shown in FIG. 19, the second stent ST2 has a reduced diameter, and the intervening membrane 11 other than the pleat 11P and the pleat 11P bites into the mesh HL of the second stent ST2 ( In addition, if there are undulations generated by winding the pleat portion 11P of the intervening membrane 11, the intervening membrane 11 other than the pleat portion 11P and the pleat portion 11P is likely to bite into the mesh HL of the second stent ST2.

  As a result, the covered stent 19 in which the intervening film 11 is bitten into the mesh HL of the first stent ST1 and the mesh HL of the second stent ST2 is attached to the balloon 31. That is, the integrated first stent ST1, the intervening membrane 11, and the second stent ST2 (that is, the covered stent 19) are mounted so as to be embedded in the expandable balloon 31, and the stent delivery catheter 49 is completed. .

  Specific examples will be described below. More specifically, the following members are used.

  The intervening film 11 is a cylindrical member having a total length of 35.0 mm, a film thickness of 32 μm, and an outer diameter of 5.9 mm. The intervening membrane 11 is a part of a straight tube in a balloon catheter (product name Senri) manufactured by Kaneka Corporation.

  The first stent ST1 and the second stent ST2 are CoCr alloy cylindrical members having a total length of 34.6 mm, a thickness of 75 μm, and an outer diameter of 1.8 mm (note that the designs of both stents ST1 and ST2 are the same). .

  The base material is a balloon 31 and has a total length of 40.0 mm, a film thickness of 24.0 μm, and an outer diameter of 4.0 mm. The balloon 31 uses a balloon shaft in a balloon catheter (product name: SHIRANUI SOFLEX) manufactured by Kaneka Corporation.

  Of the above members, first, the first stent ST1 is inserted into the parylene-coated mandrel 51 having a diameter of 1.5 mm (in other words, the first stent ST1 is coaxial with the axis of the mandrel 51. ST1 is arranged [first stent attachment step]).

  Next, the intervening film 11 is inserted so as to cover the first stent ST1 [covering step]. When the first stent ST1 is not expanded, it has an outer peripheral length of 5.65 mm, and the intervening membrane 11 has an outer peripheral length of 18.85 mm (also referred to as a total peripheral length). 13.19 mm. Therefore, with this surplus, as shown in FIGS. 9 and 10, the two pleat portions 11P are gripped by the gripping tool 52 and allowed to stand in a 60 ° C. atmosphere for 3 minutes [brazing step].

  Subsequently, the gripping tool 52 is removed, and the fold portion 11P of the intervening membrane 11 is wound around the first stent ST1 [winding step]. Thereafter, a protective tube (SST 3/32 manufactured by Pennitto Co., Ltd.) is placed on the intervening film 11 around which the pleat 11P is wound [protective tube attaching step]. Then, the intervening film 11 to which the protective tube is attached is allowed to stand again in an atmosphere of 60 ° C. for 10 minutes (Note that if one end of the protective tube is processed obliquely, workability is improved. It is preferable because it improves.)

  After this standing, the protective tube is removed, and the mandrel 51 is further extracted from the first stent ST1 [mandrel extraction step]. Then, the balloon 31 is inserted into the place where the mandrel 51 is removed, that is, the lumen of the first stent ST1 [base material insertion step]. In the insertion of the balloon 31 (specifically, the balloon shaft), another mandrel having a diameter of 0.45 mm is inserted into the guide wire lumen of the balloon shaft.

  Then, the first stent ST1 is covered on the balloon 31 supported by the mandrel, and the first crimping is performed by the crimping apparatus in a state where the first stent ST1 is covered with the intervening film 11 [first crimping. Process].

  On the other hand, after the end of the second stent ST2 is pre-expanded using a tapered mandrel, the second stent ST2 is uniformly expanded by inserting the mandrel having a diameter of 1.95 mm. Then, the expanded second stent ST2 is inserted so as to cover the intervening membrane 11 after the first crimping [second stent attachment step]. Thereafter, the second crimping is performed in a state where the second stent ST2 covers the intervening film 11 [second crimping step].

  As a result, the covered stent 19 having an outer diameter of about 1.76 to 1.82 mm is completed.

[Other embodiments]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, as shown in FIG. 10, the two pleat portions 11P in the intervening film 11 are opposed to each other with the central axis of the mandrel 51 (the position of the root of the pleat portion 11P is 180 ° with respect to the central axis of the mandrel 51). However, it is not limited to this example.

  For example, as shown in FIG. 20, four pleats 11P are formed, and the positions of the four roots are 90 ° apart from the central axis of the mandrel 51 (referred to as the central axis of the first stent ST1). May be evenly separated, or the number of pleat portions 11P may be one.

  In short, if the burial amount of the intervening film 11 in the mesh HL of the stent ST is uniformly distributed and each burial amount is sufficient, the integrity of the intervening film 11 and the stent ST is ensured. Therefore, as long as such certainty can be improved, the shape, arrangement, distribution, and the like of the pleat 11P are not particularly limited.

ST stent
ST1 First stent ST2 Second stent 11 Intervening membrane 11P Folded portion 11N Inner membrane inner surface [membrane surface]
19 Covered stent HL Stent network 31 Balloon 39 Balloon catheter 51 Mandrel 52 Gripping tool

Claims (12)

A first stent having a tubular structure and a stitch structure;
A second stent having a cylindrical and knitted structure surrounding the outer periphery of the first stent;
A cylindrical intervening membrane interposed between the outside of the first stent and the inside of the second stent;
A covered stent including
The intervening membrane is a covered stent in which a pleat portion generated by bringing the inner cylindrical membrane surfaces close to each other is wound in a cylindrical circumferential direction.   The covered stent according to claim 1, wherein the pleat portion is formed by one or a plurality.   The intervening membrane is formed of a non-stretchable material having such a property that, after expansion of the first stent and the second stent in the radial direction, the circumference of the first stent and the second stent does not extend more than before expansion. The covered stent according to 1 or 2.   The covered stent according to any one of claims 1 to 3, wherein the intervening membrane contains granules or fillers.   The covered stent according to any one of claims 1 to 4, wherein the intervening film has thermoplasticity.   3. The intervening membrane is formed of a stretchable material having a characteristic of extending the circumference of the first stent and the second stent in a radial direction after expansion in a radial direction than before expansion. The covered stent as described.   The covered stent according to any one of claims 1 to 6, wherein the intervening membrane has biocompatibility.   The covered stent according to any one of claims 1 to 7, wherein the intervening membrane has a drug releasing function. The covered stent according to any one of claims 1 to 8,
A balloon catheter to which the covered stent is attached;
A stent delivery catheter comprising:   The stent delivery catheter according to claim 9, wherein the portion to which the covered stent is attached is a balloon in the balloon catheter. A tubular first stent;
A cylindrical second stent surrounding the outer periphery of the first stent;
A cylindrical intervening membrane interposed between the outside of the first stent and the inside of the second stent;
A method for manufacturing a covered stent including:
A covering step of covering the first stent with the intervening membrane;
A winding step in which a pleat portion generated by bringing the inner cylindrical membrane surfaces of the intervening membrane closer together is wound in a cylindrical circumferential direction;
A method for producing a covered stent comprising: The method for producing a covered stent according to claim 11, wherein the winding step applies heat to the intervening film in an atmosphere at or below the glass transition temperature of the intervening film.