JP2008000193A - Self-expanding stent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-expanding stent in which jump is suppressed. <P>SOLUTION: The self-expanding stent deforms in a direction of reducing the external diameter when an external load is applied and restores its original shape before applying the load when the external load is released. The stent comprises a stent body 12 and a stent end part 15 connected to one end of the stent body. The expanding force of the stent end part is 0.05-0.84 N/cm and the expanding force of the stent body is 1.2-3.0 times larger than that of the end part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a self-expanding stent that is implanted in a hollow organ such as a blood vessel or a bile duct, and more particularly, the stent can be accurately released to an indwelling position when released into the hollow organ by a stent delivery system. It relates to a self-expanding stent.

  Stents are generally tube-shaped devices used to radially expand stenosis or occlusions of blood vessels, bile ducts, trachea, esophagus, urethra, and other hollow organs. Moreover, it is used also for the application which reinforces a board, such as supporting and holding the inner layer of the incised artery. As such a stent, a balloon expandable stent in which a balloon disposed inside the stent is expanded, the stent is expanded by the expansion force of the balloon, and the stent is indwelled at the indwelling target position, and the stent itself has a restoring force. These are roughly divided into two types: self-expandable stents that are compressed in advance, mounted on a stent delivery system, released and then expanded by their own restoring force, and the stent is placed in a hollow organ. .

  Balloon expandable stent expands the stent by balloon inflation and has low expansion force, suffers from severe trauma such as falling down in daily life, and when the indwelling portion is subjected to strong force, the stent collapses and the patient is injured In some cases, the indwelling treatment time is required because the indwelling is performed by inflation of the balloon. In contrast, self-expanding stents are highly resistant to external pressure and expand immediately upon release from the stent delivery system, which shortens the processing time required for attachment to the hollow organ. For this reason, in recent years, self-expanding stents are frequently used for blood vessels, bile ducts, and the like.

  As such a self-expanding stent, for example, helical filaments are disposed on a first tubular layer, and the helical filaments are in phase with each other such that they are placed in one plane without contact. There is a stent that is displaced and is completely covered by a second elastic tubular layer joined to the first elastic tubular layer (Patent Document 1). The conventional stent is configured by processing the net into the shape of the stent in order to secure the self-restoring force, but the stent described in Patent Document 1 does not use the net and is hollow with a simple configuration of a spiral structure. It was made for the purpose of attaching to organs safely, permanently and so as not to come off.

  There is also a stent that is intended to be placed at the entrance / exit of the lumen (Patent Document 2). When pancreatic head cancer grows and cancer develops in the nipple and obstructs the nipple from the lower common bile duct, the stent remains in the duodenum even if the stent is placed to penetrate the lower common bile duct, the nipple and the duodenum. It may fall off to the side or move to the common bile duct side, and it is difficult to place it accurately. Patent Document 2 solves this, and has a cylindrical main body portion whose diameter decreases from one end side toward the other end side, and the other end portion of the main body portion or the vicinity of the other end portion with respect to the axial direction of the stent. And a stent that is integrally provided with an in-vivo locking portion that extends obliquely.

  Such a self-expanding stent is contracted by applying an external pressure to be reduced in diameter, mounted inside the outer tube tip of the stent delivery system, and placed in a living body using this system (Patent Document 3). Specifically, as shown in FIG. 8A, the stent 100 is engaged with the inner tip of the outer cylinder 130, and the inner cylinder 140 is coaxially disposed in the lumen of the stent 100. The X-ray tips 150a and 150b provided at the tip of the inner cylinder 140 are inserted into the detention target position 160 while confirming the position, and the outer cylinder 130 is moved to the inner cylinder base end 145 side at the detention target position 160. The stent 100 is released from the outer tube 130 by pulling. Thereby, the stent 100 engaged with the inner side of the outer cylinder 130 is self-expanded, and the stent 100 is placed at the placement target position 160 as shown in FIG. Later, the inner tube 140 is withdrawn from the lumen of the stent 100 and collected.

There is also a technique related to a self-expanding stent delivery system that can accurately and easily place a stent in a target region (Patent Document 4). The system described in Patent Document 4 provides a self-expanding stent delivery system capable of guiding a tortuous path, preventing the stent from being embedded, and accurately and easily placing the stent. The inner wall of the outer cylinder is covered with a pyrolytic carbon layer, which prevents the self-expandable stent from being embedded in the outer cylinder and damage to the stent during stent placement, thus reducing the force required for stent placement. This makes it easier to place the stent and allows the stent to be placed more accurately.
JP 2003-325673 A JP 2005-21504 A JP 2004-181230 A JP 2003-265619 A

  However, when the self-expanding stent is placed using the stent delivery system, the stent 100 actually has a strong expansion force, so that the end of the stent 100 is released from the outer tube 130 as shown in FIG. At this time, since the end portion of the stent rapidly expands, the expansion force becomes a driving force, and the stent 100 may jump out beyond the indwelling position 160 as shown in FIG. 9B. Such a phenomenon is a phenomenon peculiar to a self-expanding stent having a strong expansion force, and is not regarded as a problem in a balloon expandable stent.

  When performing stent placement, the position is confirmed in advance by injecting a contrast medium, etc., but it is difficult to accurately grasp in millimeters, and the stent has popped out due to the expansion force of the stent end, It becomes more difficult to accurately insert the stent at the indwelling target position.

  Therefore, an object of the present invention is to provide a stent that is a self-expanding stent and that can be prevented from popping out of the stent delivery system and can be accurately fixed at an indwelling target position.

  As a result of detailed examination of the behavior of the stent when the self-expanding stent is placed by using the stent delivery system, the present inventor found that the self-expanding stent pops out easily when the expansion force of the stent is strong. Therefore, if the expansion force of only the end of the stent that comes into contact with the outer cylinder at the time of release from the stent delivery system is controlled within a specific range, the stent can be prevented from popping out, and the expansion force of the stent body can be prevented. It is found that the stenosis can be effectively expanded and the lumen can be secured, and even when a strong pressure is applied from the outside after placement, the stent can be effectively blocked. Completed.

  According to the self-expanding stent of the present invention, it is possible to place the self-expanding stent that does not require special learning and is difficult to position at the intended placement position.

  The self-expanding stent of the present invention can be formed by attaching a stent end portion having a specific expansion force to the end portion of the stent body portion, is easy to manufacture, and is widely applied to conventional self-expanding stents. can do.

  Moreover, in the self-expanding stent of the present invention, if only the expansion force at one end of the stent main body is limited to a predetermined range, the other end and the main body can ensure the conventional expansion force. Therefore, it can exhibit a strong expansion force that effectively expands the stenosis when placed in a living body lumen, and can exert a strong expansion force even when external pressure is applied after placement in the living body.

  According to the self-expanding stent of the present invention, a conventional stent delivery system can be used to place the stent accurately, and no special delivery system is required.

The present invention is a self-expanding stent whose outer diameter can be deformed in the direction of diameter reduction by an external pressure load and can be restored to the shape before the external pressure load by releasing the external pressure,
The stent includes a stent body and a stent end connected to one end of the stent body, and an expansion force of the stent end is 0.05 to 0.84 N / cm. This is a self-expanding stent having a part expansion force of 1.2 to 3.0 times that of the end part.

  The self-expanding stent is loaded inside the outer tube of the stent delivery system while applying an external pressure to reduce the diameter of the stent. This prevents the stent from expanding before being released, and after being released from the stent delivery system. The shape before the external pressure load is restored at the indwelling location by its own restoring force. The present invention is such a self-expanding stent, comprising a stent main body portion and a stent end portion connected to one end thereof, and an expansion force of the stent end portion is 0.05 to 0.84 N / cm. , Preferably 0.10 to 0.68 N / cm, particularly preferably 0.18 to 0.52 N / cm, and the expansion force of the stent body is 1.2 to 3.0 times that of the stent end. , Preferably 1.3 to 3.0 times, particularly preferably 1.5 to 3.0 times. When the expansion force at the end of the stent is less than 0.05 N / cm, the end of the stent may be easily blocked when the stenotic lesion is enlarged. On the other hand, if it exceeds 0.84 N / cm, the stent may pop out when released from the stent delivery system, and it may be difficult to release to the intended indwelling position. On the other hand, if the expansion force of the stent body is less than 1.2 times the expansion force of the stent end, it may be difficult to rapidly expand the stenosis, while if it exceeds 3.0 times, the stent delivery Release from the system may be difficult.

  Note that the expansion force of the stent body and the end of the stent differ depending on the outer diameter of the stent during expansion even if other elements are the same. However, the stent jump force upon release from the stent delivery system depends only on the stent end expansion force, regardless of the outer diameter of the stent end. Therefore, in the present invention, the expansion force of the stent end is defined within a specific range, while the expansion force of the stent body is defined by a ratio to the expansion force of the stent end. In the present invention, the expansion force of the stent is measured by the method described in the examples described later.

  The shape of the stent of the present invention is not particularly limited as long as the above conditions are satisfied. Preferably, the stent body is formed by connecting a plurality of stent body annular elements by connecting elements, and the stent end is also formed. One or more stent end annular elements are connected to the stent body annular element by a connecting element. When the stent body is composed of a plurality of annular elements, when external pressure is applied after being placed in the living body, each annular element can individually face the external pressure, so it fits in with the shape of the intended placement place in the living body. It is easy to minimize deformation when external pressure is applied.

  FIG. 1 (a) shows a partially developed view of the stent of the present invention cut along the major axis, and FIG. 1 (b) shows another shape of the stent body. In the present invention, the stent body (10) is formed by connecting a plurality of annular elements (12) by a connecting element (30), and a stent end (20) is provided at one end of the stent body (10). ing. Here, the stent body portion annular element (12) is one unit constituting the stent body portion, and is connected by the connecting element (30). In the present invention, the shape of the plurality of stent body part annular elements (12) included in the stent body part (10) may be the same or different.

  Here, as shown in FIG. 1A, the stent body portion annular element (12) is preferably composed of, for example, a linear body 17 connected in a wavy and annular shape. This is because a linear body can be easily reduced in diameter by an external pressure load when attached to a stent delivery system. The number of peaks / valleys included in the stent body annular element (12) can be appropriately selected according to the intended use and size of the stent and the in-vivo indwelling site. There are 8 to 60, more preferably 10 to 50, and particularly preferably 10 to 35 in the element (12). Similarly, the length of the stent body (10) is preferably 20 to 150 mm, more preferably 30 to 120 mm, and particularly preferably 40 to 100 mm. Moreover, the number of the stent body part annular elements (12) included in the stent body part (10) is 4 to 60, more preferably 7 to 50, and particularly preferably 10 to 40.

  FIG. 2 shows various partial development views of a preferred stent body of the present invention. In the present invention, the stent body annular element (12) is preferably a wavy linear body having a crest and a trough, and the shape of the crest or trough is, for example, as shown in FIG. In addition to the wavy linear body having acute crests and troughs, as shown in FIG. 2 (b), even a wavy linear body composed of semicircular crests and troughs As shown in 2 (c), the shape may have a depression at the center of the peak or valley, and the wavy may not be symmetrical if it has a valley and a peak.

  The linear body in the present invention is composed of a linear object in advance, for example, by forming a linear gap on an annular plate and punching a hexagonal shape as shown in FIG. However, the present invention is not limited to the case.

  In the present invention, the connecting element (30) that connects the plurality of stent body annular elements (12) may be connected to any part of the stent body annular element (12), and the number thereof is not limited. For example, in FIG. 1A, the stent body annular elements (12) arranged side by side are arranged so that the crests and troughs are adjacent to each other, and the connecting element (30) is also connected every three crests. In FIG. 1 (b), an aspect in which the connecting portions are mixed for every four peaks is arranged so that the peaks and valleys of the stent body annular elements (12) lined up with each other are adjacent to each other. The aspect in which a connection element (30) is arbitrarily provided between each stent main-body-part annular elements (12) is shown.

  Moreover, in this invention, as shown to Fig.2 (a), as shown in Fig.2 (a), the connecting element ( 30) may be a mode of connecting a valley and a valley or a mountain and a mountain. On the other hand, as shown in FIG. 2 (b), the peak and valley are connected, and the leftmost annular element is referred to as the first annular element (12) and the second annular element in this order. The connection positions of the first annular element (12) and the second annular element (12) are the connection positions of the third annular element (12) and the fourth annular element (12), and the fifth annular element ( 12) and the sixth annular element (12) are repeated, and similarly, the connecting position of the second annular element (12) and the third annular element (12) is the fourth annular element ( 12) is repeated in the connection between the fifth annular element (12) and the connection between the sixth annular element (12) and the seventh annular element (12), etc. The aspect connected by a connection element (30) may be sufficient. Furthermore, like the stent main body shown in FIG. 2 (c), the crest and crest of each stent main body annular element (12) or the trough and trough are connected. It may be an aspect that is repeated at a predetermined interval. Further, unlike FIG. 1 (b), FIG. 2 (d) is arranged so that the crests and troughs of the stent body annular elements (12) arranged side by side are adjacent to each other, and the connecting element (30). Are regularly provided at the same position between the annular elements (12).

  Furthermore, FIG. 3 shows various partial development views of a preferred stent body of the present invention. In FIG. 3 (a), the crests and troughs of adjacent stent body annular elements (12) are disposed so that the crests and troughs are all at the same angle with respect to the longitudinal direction of the stent. A mode in which the connecting elements (30) are obliquely connected to each other is shown in FIG. 3 (b) in such a manner that the crests and troughs of the adjacent stent body annular elements (12) approach each other. FIG. 3 (c) shows an aspect having a portion connected with the connecting element (30) obliquely with respect to the longitudinal direction of the stent and a portion connected in parallel with each other in FIG. 12) is arranged so that the crests and troughs are close to each other, and the crests and troughs are connected in parallel to the points where the connecting elements (30) are connected obliquely with respect to the longitudinal direction of the stent. However, the angle of the diagonal connection with respect to the longitudinal direction of the stent is In FIG. 3 (d), the different stent body annular elements (12) are arranged so that the peaks and valleys approach each other, and the peaks and valleys are in the longitudinal direction of the stent. The third annular element (12) and the fourth annular element are connected to each other in parallel by the connecting element (30), and are referred to as the first annular element, the second annular element in order from the leftmost annular element. An annular element (12) shows the aspect by which a peak part and a trough part are connected by the double link by the connection element (30). In addition, a double link means the aspect with which the adjacent annular element (12) is connected by two adjacent connection elements (30). In addition, the aspect with which the adjacent annular element (12) is connected by one connection element (30) is called single link.

  Note that the self-expanding stent is appropriately selected in terms of the stent length, inner diameter, outer diameter, and expansion force according to the shape of the placement site. It is preferably 0.15 to 1.50 N / cm, more preferably 0.20 to 1.25 N / cm, and particularly preferably 0.25 to 1.00 N / cm. If it is less than 0.15 N / cm, it may be difficult to rapidly expand the constriction, while if it exceeds 1.50 N / cm, it may be difficult to attach the stent delivery system.

  On the other hand, the stent end is composed of one or more stent end annular elements, and the stent end is connected to the stent body annular element by a connecting element. Further, in the present invention, the stent end is an end connected to one end of the stent main body, and may be provided at either one of both ends of the self-expanding stent. The stent end need not be present. Rather, the end of the stent preferably exists only at one end of the stent body, and the end is the end that comes into contact with the outer tube last when released from the stent delivery system. It is. When this stent end is released from the external pressure load by the outer cylinder, it is found that the restoring force of the stent end provides a forward driving force, and the release to the indwelling target position is suppressed by suppressing this driving force. Because it makes things easier.

  As shown in FIG. 1A, it is preferable that the annular element (15) constituting the end of the stent is also composed of a linear body (17). This is because it is easy to manufacture and connect to the stent body. Moreover, when it consists of a some stent end cyclic | annular element (15), each stent end cyclic | annular element (15) is also connected by the connection element (30).

  In the present invention, the shape of the stent body annular element (12) and the stent end annular element (15) and the shape and number of the coupling elements (30) are not limited, and the expansion force of the stent end is 0 as described above. It may be 0.05 to 0.84 N / cm, and the expansion force of the main body may be 1.2 to 3.0 times that of the end.

  In order to provide a difference in expansion force between the stent body and the stent end, for example, the stent body annular element (12) and the stent end annular element (15) may have different shapes, For connecting the connecting elements (30) between them, for example, the length and connecting interval of the connecting elements (30) in the long axis direction, the thickness of the connecting elements (30), each stent body portion annular element (12) and stent end ring It can be adjusted by providing a difference in the members constituting the element (15).

  For example, as a method of giving a difference in the shape of the linear body constituting the annular element, the stent end annular element (15) is composed of a wavy linear body having 9 to 70 peaks or valleys. When the stent body annular element (12) is composed of a wave-like linear body having 8 to 60 peaks or valleys, the stent end annular element is the stent body part. Compared with the annular element, the number of peaks included in one annular element is set to be at least one more. Thus, if the number of ridges included in one annular element at the end of the stent is greater than the number of ridges included in the stent body annular element, the outer diameter and inner diameter should be the same. For example, the expansion force of the stent end annular element can be reduced more than the expansion force of the stent body annular element. In the present invention, the number of the crests or valleys of the stent end annular element (15) is increased by 1 to 10, and preferably by 2 to 6, more than the stent main body annular element (12). For example, when the stent is a biliary stent having a total length of 60 to 100 mm and an outer diameter of 6 to 10 mm, the stent body portion annular element (12) has 12 to 18 peaks, and the stent end portion is annular. Element (15) can be prepared to have 14-20 peaks.

  Further, the length of the stent end annular element (15) in the major axis direction is set to be longer than the length of the stent body annular element (12) in the major axis direction, so that the stent body annular element and the stent end ring The expansion force with the element can be controlled within the above range. Further, even if the shapes of the wavy linear bodies constituting the stent body annular element (12) and the stent end annular element (15) are the same, the thickness of the stent end annular element (15) is reduced. By making it thinner than the thickness of the annular element (12), the expansion force between the stent body annular element and the stent end annular element can be controlled within the above range. In these, when a cyclic | annular element consists of a linear body, the number and shape of the peak part and valley part which are included, and each connection method may be the same or different, and adjustment of an expansion force is any one of said 2 The above may be combined.

  Moreover, even if the shape and thickness of the wavy linear body constituting the stent body annular element (12) and the stent end annular element (15) are the same, the linear body of the stent body annular element (12) By making the thickness of the stent larger than that of the linear body of the stent end annular element (15), the expansion force between the stent body and the stent end can be controlled within the above range.

  As a connecting method of a plurality of stent body annular elements (12) and a connecting element (30) for connecting stent end annular elements (15), only the stent body annular element (12) is connected by a double link. The partial annular element (15) can be limited to the expansion force by connecting with a single link. Since the single link has a weaker expansion force than the double link, the end extension force can be suppressed within the above range by connecting the annular elements at the end with a single link.

  Further, by using materials having different restoring forces to restore the original shape of the members constituting the stent, the expanding force between the stent body and the stent end can be limited to the above range.

  The self-expanding stent of the present invention is used to improve a stenosis or occlusion in a lumen such as a blood vessel, bile duct, trachea, esophagus, urethra, and other organs, and has a suitable size depending on the placement position. Can be selected and used. As described above, the size of the stent main body varies depending on the indwelling target site.For example, the stent length is 20 to 100 mm for blood vessels, the outer diameter is 4 to 16 mm, and the stent length is 70 to 150 mm for esophagus. An outer diameter of 18 to 23 mm, a stent length of 30 to 80 mm and an outer diameter of 8 to 40 m for trachea, and a stent length of 20 to 120 mm and an outer diameter of 5 to 10 mm can be suitably used for bile ducts. The stent can be used for any of the above applications.

  In the present invention, conventionally known self-expanding stent manufacturing materials can be used as the material for forming the stent. One such material is Nitinol, a nickel titanium shape memory alloy. Moreover, the superelastic metal which shows superelasticity at the biological temperature (near 37 degreeC) described in Unexamined-Japanese-Patent No. 2005-21504 may be sufficient.

  At this time, the self-expandable stent of the present invention, the stent body portion and the stent end portion constituting the stent are removed by cutting or dissolving the non-stent portion using, for example, a nickel titanium or superelastic metal pipe. Can be manufactured. The formation of the stent base material by the pipe can be performed by laser processing (for example, YAG laser), electric discharge processing, chemical etching, cutting processing, or the like, and may be performed by a combination thereof.

  The self-expanding stent of the present invention may be integrally manufactured while adjusting the number of crests of the stent body and the end of the stent, the thickness, the length of the annular element in the long axis direction, or the like, or The stent main body portion having a predetermined restoring force may be manufactured by connecting a stent end portion having a predetermined restoring force with a connecting element. For example, the self-expandable stent of the present invention can be integrated by processing the linear body constituting the stent body annular element and the linear body constituting the stent end annular element with a difference in shape. Can be manufactured. Further, by using the above material, the expansion force is adjusted in advance by providing the pipe with a thickness at a portion corresponding to the stent end portion and a portion corresponding to the stent body portion, and the self-expandable stent of the present invention is provided. You may manufacture integrally. Similarly, the material corresponding to the portion corresponding to the stent end and the portion corresponding to the stent body are made different in advance, thereby adjusting the expansion force between the stent body and the stent end, and the self-expanding type of the present invention. The stent may be manufactured integrally.

  The stent of the present invention can also be manufactured by connecting a stent end portion having an expansion force in the above range to one end portion of a conventional self-expanding stent.

  The stent of the present invention may be coated with a biocompatible material on the inner surface and / or outer surface of the stent. As such a biocompatible material, a synthetic resin or metal having biocompatibility can be considered.

  The synthetic resin can be selected from thermoplastic or thermosetting resins, such as polyolefin (eg, polyethylene, polypropylene, ethylene-propylene copolymer, etc.), polyvinyl chloride, ethylene-vinyl acetate copolymer, polyamide. Elastomers, polyurethanes, polyesters, fluororesins, silicone rubbers, etc. can be used, preferably polyolefins, polyamide elastomers, polyesters or polyurethanes, and biodegradable resins (eg polylactic acid, polyglycolic acid, copolymers of both) is there. The synthetic resin coating is preferably flexible to the extent that it does not hinder the bending of the frame constituting the stent. The thickness of the synthetic resin coating is 5 to 300 μm, preferably 10 to 200 μm. As a method of thinly coating the surface of the stent with a synthetic resin, for example, a method in which a superelastic metal pipe is inserted into a synthetic resin in a molten state or a solution state, and a monomer is polymerized on the surface of the superelastic metal pipe. There are chemical vapor deposition and the like to coat while. When an extremely thin resin coating is required, coating using a dilute solution or chemical vapor deposition is preferable.

  In addition, as a method for coating the surface of the stent with an inert metal, gold plating using an electroplating method, stainless steel plating using a vapor deposition method, silicon carbide using a sputtering method, titanium nitride plating, gold plating, or the like can be considered. .

  Furthermore, in order to further improve biocompatibility, an antithrombotic material may be coated or fixed on the resin coating. As the antithrombogenic material, various known resins can be used alone or in combination. For example, polyhydroxyethyl methacrylate, a copolymer of hydroxyethyl methacrylate and styrene (for example, HEMA-St-HEMA) Block copolymers) can be used preferably.

  Note that the expansion force of the stent when released from the stent delivery system is not limited to the expansion force at the end of the stent, but also varies depending on the inner diameter of the outer cylinder of the stent delivery system. The self-expanding stent of the present invention is attached to a stent delivery system that has been suitably selected from the viewpoint of the size of the stent and the expansion force of the stent body, and reduces the expansion force of the stent end. Suppresses jumps during release. Therefore, the self-expandable stent of the present invention is inserted into the outer tube from the end of the stent of the present invention when mounted on the stent delivery system.

  The self-expanding stent of the present invention is used to improve a stenosis or occlusion occurring in a lumen such as a blood vessel, bile duct, trachea, esophagus, urethra, or other organs. There is no. Therefore, for example, when performing biliary stenting for obstructive jaundice or acute biliary hepatitis associated with a pancreatobiliary disease, it may be percutaneous transhepatic or transendoscopic.

  EXAMPLES Next, although an Example is given and this invention is demonstrated concretely, these Examples do not restrict | limit this invention at all. In addition, the measurement in a test example followed the following.

Measurement method (1) The expansion force was measured using the apparatus shown in FIG. First, the repulsion of the stent obtained when it is set in parallel to the lower plate of the jig 120 capable of reducing the diameter of the entire 120 mm stent in a tensile tester and crushed to 50% of the initial outer diameter at a speed of 200 mm / min. The force was measured. The measurement was performed three times at different locations in the radial direction, the average value was obtained, and the obtained value was divided by the stent length to obtain the expansion force per stent unit length (1 cm).

  (2) The stent was mounted on the stent delivery system shown in FIG. 6A, set in the tensile tester shown in FIG. 6B, the Y connector was pulled up at a speed of 100 mm / min, and the stent 100 was released. The distance between the end portion of the stent and the outer cylinder later was defined as a stent jump force. The stent delivery system has a tube outer diameter of 2.36 mm ± 0.04, a tube inner diameter of 2.00 mm ± 0.04, a tube material of tetrafluoroethylene resin, and a blade used by Mitsui DuPont Fluorochemical Co., Ltd. The product name is “640-j” and the delivery effective length is 1,000 mm.

(Test Example 1)
FIG. 4 (FIG. 4) shows a metal pipe having an outer diameter of 8.0 ± 1 mm, a wall thickness of 0.20 ± 0.02 mm, and a length of 60 ± 1 mm, prepared by cold working an alloy pipe of a TiNi alloy (51 atomic% Ni). It processed into the wavy linear body shown to a) and (b). The annular element shown in FIG. 4A is composed of a wavy linear body composed of 14 peaks, and the annular element shown in FIG. 4B is composed of a corrugated linear body composed of 16 peaks. As a result, the angle of the peak portion of the wavy linear body shown in FIG. 4C was 43.5 ° in FIG. 4A and 35.2 ° in FIG. 4B. Further, the height L of the wavy linear body was 2.85 mm in FIG. 4A and 2.91 mm in FIG. 4B. In FIG. 4 (a), adjacent annular elements are connected by a double link (WL) connected at two consecutive points every five peaks, and the double link position is 90 ° in the connection with the next annular element. Similarly, in the stent of FIG. 4 (b), the adjacent annular elements are connected by double links (WL) joined at two consecutive points every six peaks, and In the connection with the annular element, the double link position is shifted by 90 °. The expansion force was measured for this stent. The results are shown in Table 1.

(Test Example 2)
A stent was prepared in the same manner as in Test Example 1 except that the number of peak portions of the wavy linear body was set to 12, and the expansion force was measured in the same manner as in Test Example 1. In addition, the angle of the peak part shown in FIG.4 (c) was 47.8 degrees, and the height L of the wavy linear body was 2.85 mm. The results are shown in Table 1.

（試験例３）
試験例１、２で調製したステントを使用し、ステントデリバリーシステムの外筒内径が２．０ｍｍのステントデリバリーシステムからリリースした後のジャンプ力を、ジャンプ長さで評価した。結果を表２に示す。波状線状体の山部または谷部の数が多くなると、ジャンプ力が低減した。

(Test Example 3)
Using the stents prepared in Test Examples 1 and 2, the jump force after the stent delivery system was released from the stent delivery system having an inner cylinder inner diameter of 2.0 mm was evaluated by the jump length. The results are shown in Table 2. As the number of peaks or valleys of the wavy linear body increased, the jumping force decreased.

（実施例１）
ＴｉＮｉ合金（５１原子％Ｎｉ）の合金パイプを冷間加工して調製した、外径８±１ｍｍ、肉厚０．２±０．０２ｍｍの金属パイプを、長さ６０±１ｍｍの図７に示すように波状線状体に加工した。ステント本体部（１０）は長さ５３〜５５ｍｍ、ステント端部（２０）は５〜７ｍｍとした。ステント本体部環状要素（１２）では１４の山部からなる波状線状体とし、ステント端部環状要素（１５）は１６の山部からなる波状線状体とした。これにより、図４（ｃ）に示す波状線状体の山部の角度は、ステント本体部環状要素では、図４（ａ）と同様の４３．５°となり、ステント端部環状要素では図４（ｂ）と同様の３５．２°となった。なお、図４（ａ）のステントは、隣接する環状要素は５つの山部ごとに連結する２箇所で結合するダブルリンク（ＷＬ）によって連結され、かつ次の環状要素との連結においてダブルリンク位置が９０°づつ位置がずれる連結形態であり、同様に図４（ｂ）のステントも、隣接する環状要素は、６つの山部ごとに連続する２箇所で結合するダブルリンク（ＷＬ）によって連結され、かつ次の環状要素との連結においてダブルリンク位置が９０°づつ位置がずれる連結形態であり、ステント本体部環状要素（１２）とステント端部環状要素（１５）とも等間隔のダブルリンク２箇所によって連結させた。

(Example 1)
A metal pipe having an outer diameter of 8 ± 1 mm and a wall thickness of 0.2 ± 0.02 mm, prepared by cold working an alloy pipe of TiNi alloy (51 atomic% Ni) is shown in FIG. 7 having a length of 60 ± 1 mm. In this way, it was processed into a wavy linear body. The stent body (10) was 53-55 mm long and the stent end (20) was 5-7 mm. The stent body annular element (12) was a wavy linear body consisting of 14 peaks, and the stent end annular element (15) was a wavy linear body consisting of 16 peaks. Accordingly, the angle of the peak portion of the wavy linear body shown in FIG. 4C is 43.5 ° in the stent body annular element as in FIG. 4A, and in the stent end annular element, FIG. It became 35.2 degrees similar to (b). In the stent of FIG. 4A, adjacent annular elements are connected by double links (WL) that are connected at two points where every five peaks are connected, and in the connection with the next annular element, a double link position is established. Similarly, in the stent of FIG. 4B, the adjacent annular elements are connected by double links (WL) which are connected at two consecutive points every six ridges. In addition, the double link position is shifted by 90 ° in connection with the next annular element, and the stent body annular element (12) and the stent end annular element (15) are equally spaced two double links. Connected by

  Using this stent, the jump force after release from the stent delivery system was measured and found to be 22 mm.

  According to the present invention, it is possible to manufacture the self-expandable stent of the present invention only by limiting the end of the conventional stent to a specific range of expansion force, and this stent can be accurately placed at a target position. Can and is useful.

The development which cut and opened the stent of this invention along the major axis is shown. FIG. 1 (a) shows an embodiment in which an annular element is constituted by a wavy linear body, and FIG. 1 (b) shows an embodiment formed by punching a hexagonal shape by providing a linear gap on an annular plate. . It is a figure which shows the aspect of the annular element which comprises the stent main-body part or edge part of this invention. It is a figure which shows the connection method of the annular element which comprises the stent main-body part or edge part of this invention. It is a figure explaining the stent prepared in the Example, (a) And (b) is a side view of a stent. It is a figure which shows the method of measuring the expansion force of the stent of this invention. It is a figure explaining the method to measure the jump force of the stent after releasing from a stent delivery system. 1 is a side view of a self-expanding stent of the present invention. It is a figure explaining the method of indwelling a self-expanding stent in an indwelling destination location using a stent delivery system. It is a figure explaining the jump of the stent at the time of indwelling a self-expandable stent in an indwelling destination location using a stent delivery system.

Explanation of symbols

10 ... stent main body,
12 ... Stent body annular element,
15 ... Stent end annular element,
20 ... End of stent,
17 ... linear body,
30 ... connecting element,
100 ... stent,
120 ... Jig,
130 ... outer cylinder,
140 ... inner cylinder,
145 ... Inner cylinder base end 150 ... X-ray chip,
160 ... Placement target place 200 ... Stent delivery system.

Claims (11)

A self-expandable stent whose outer diameter can be deformed in the direction of diameter reduction by an external pressure load and can be restored to the shape before the external pressure load by releasing the external pressure,
The stent includes a stent body and a stent end connected to one end of the stent body, and an expansion force of the stent end is 0.05 to 0.84 N / cm. A self-expanding stent having an expansion force of 1.2 to 3.0 times that of the end.   The stent body is formed by connecting a plurality of stent body annular elements by connecting elements, and the stent end part is connected by one or more stent end annular elements to the stent body annular elements by connecting elements. The self-expanding stent according to claim 1, wherein:   The self-expanding stent according to claim 1 or 2, wherein the stent body annular element and / or the stent end annular element is formed of a linear body.   The said linear body is a wavy linear body which has a peak part and a trough part, The said connection element connects the said peak part, a peak part, and / or a trough part, The Claim 3 Self-expanding stent.   The self-expanding stent according to any one of claims 2 to 4, wherein the stent has two or more connecting elements between adjacent stent main body portions and / or annular elements at the end of the stent.   The said stent end annular element has many crests contained in one annular element compared with the said stent main body annular element, The self in any one of Claims 4-5 characterized by the above-mentioned. Expandable stent.   The self-expanding stent according to any one of claims 1 to 6, wherein the stent end annular element has a longer length in the longitudinal direction than the stent body annular element.   The self-expanding stent according to any one of claims 1 to 7, wherein the stent end annular element has a smaller thickness than the stent body annular element.   The self-expanding stent according to any one of claims 1 to 8, wherein the material of the stent is made of a super elastic metal or a nickel titanium alloy.   The self-expanding stent according to any one of claims 1 to 9, wherein the stent main body and the stent end are formed of different materials.   The self-expanding stent according to any one of claims 1 to 10, wherein an expansion force of the stent main body portion is 0.15 to 1.50 N / cm.

Images