Plastic stent

Abstract

The present invention provides a plastic stent comprising: a front end part formed in a tube shape such that an inlet is formed at one side thereof; a central part having one side integrally extending from the front end part; and a rear end part integrally extending from the other side of the central part, and having an outlet formed at the end of a flow path communicating with the inlet, wherein the front end part and the rear end part provide different restoring angles or restoring forces with respect to the central part. In addition, the present invention provides a plastic stent comprising: a front end part formed in a tube shape such that an inlet is formed at one side thereof; a central part having one side formed in a tube shape so as to be integrated with the front end part; a rear end part which is integrally formed in a tube shape on the other side of the central part and which has an outlet communicating with the inlet; and a marker part for encompassing, with a metal material, the outer peripheral surface of at least one or more of the front end part, the central part and the rear end part.

Description

plastic stent

[0001] The present invention relates to a plastic stent that helps bile or pancreatic fluid drain into the duodenum using endoscopic retrograde cholangiopancreatography (ERCP).

[0002] Generally, a biliary stent is an interventional procedure of the pancreaticobiliary system in which a biliary stent is inserted to relieve biliary obstruction caused by bile duct cancer or pancreatic cancer.

[0003] Biliary obstruction refers to the narrowing or blockage of the bile duct, which carries bile produced in the liver to the duodenum, by gallstones or tumors (malignant or benign).

[0004] When biliary obstruction occurs, utilizing this information aids in differential diagnosis because there are common diseases associated with the site of obstruction. Hilar biliary obstruction is common in cholangiocarcinoma, gallbladder cancer, and metastatic cancer, and rarely occurs in biliary invasion by hepatocellular carcinoma. Obstruction of the middle portion of the common bile duct may be caused by pancreatic cancer, cholangiocarcinoma, iatrogenic stricture, metastatic cancer, sclerosing cholangitis, or chronic pancreatitis. Common causes of distal biliary obstruction include pancreatic cancer, ampullary cancer, duodenal cancer, distal cholangiocarcinoma, and ampullary stricture.

[0005] The most characteristic symptom of biliary atresia is obstructive jaundice (severe jaundice), which is accompanied by upper abdominal pain, fever, and severe itching. If symptoms of biliary atresia appear, biliary drainage, biliary dilation, or biliary stenting must be performed, or surgical intervention must be undertaken, to ensure that bile flows properly from the biliary tract to the digestive organs.

[0006] This procedure is absolutely necessary, especially for patients with bile duct cancer and pancreatic cancer, as bile duct obstruction occurs almost inevitably.

[0007] Stent insertion can improve the quality of life by enhancing the effectiveness of anticancer and radiation therapy while reducing the occurrence of jaundice, sepsis, and complications. Severe jaundice occurs when biliary obstruction develops during anticancer treatment, which necessitates discontinuing the treatment; therefore, biliary stent placement is effective in alleviating patient symptoms and shortening the treatment period.

[0008] However, conventional stent structures are composed of straight or pigtail types, and problems are being raised regarding the potential for these stents to cause damage by puncturing or perforating the bile duct due to their elastic restoring force.

[0009] The present invention aims to solve such problems, and more specifically, to provide a plastic stent that helps bile or pancreatic fluid drain into the duodenum using endoscopic retrograde cholangiopancreatography (ERCP).

[0010] The problems of the present invention are not limited to those mentioned above, and other unmentioned objectives will be clearly understood by those skilled in the art from the description below.

[0011] To achieve the above objective, the present invention provides a plastic stent comprising: a front end formed in a tubular shape with an inlet formed on one side; a central part extending integrally with the front end on one side; and a rear end extending integrally with the other side of the central part and having an outlet formed at the end of a flow path communicating from the inlet; wherein the front end and the rear end provide different restoration angles or restoration forces with respect to the central part.

[0012] The above tip may be formed as a hook type or a half pigtail type bent from one side of the center.

[0013] The tip portion may be formed with any one of a first restoration angle formed in the range of 30 to 70° from one side of the center, a second restoration angle formed in the range of 90 to 135°, a third restoration angle formed in the range of 135 to 180°, and a fourth restoration angle formed in the range of 180 to 270°.

[0014] The above rear end may be formed as a twisted pigtail type so as to overlap each other at least once.

[0015] The above rear end can be formed as a half pigtail type that is bent so as not to overlap each other.

[0016] The above-mentioned tip portion is made of a metal material and may include a first marker arranged to surround the tip portion adjacent to the inlet.

[0017] It may include a second marker made of a metal material and provided at both ends of the central part.

[0018] The above-mentioned tip may include a first flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the tip.

[0019] The above rear end may include a second flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the above rear end.

[0020] The above-mentioned front or rear end is provided with a first locking groove formed by cutting a part of the outer surface adjacent to the inlet or outlet, and position adjustment can be achieved by a catheter coupled to the first locking groove.

[0021] In addition, the present invention provides a plastic stent comprising: a front end formed in a tubular shape with an inlet formed on one side; a central part formed in a tubular shape on one side integrally with the front end; a rear end formed in a tubular shape on the other side integrally with the central part and having an outlet formed in communication with the inlet; and a marker part provided to wrap the outer surface of at least one or a plurality of the front end, central part, and rear end with a metal material.

[0022] The above marker portion may include a first marker arranged to be adjacent to the inlet of the tip portion and to surround the outer surface of the tip portion, and a second marker arranged at both ends of the center portion and to surround the outer surface of the center portion.

[0023] The above-mentioned leading and trailing ends can provide different restoration angles or restoring forces with respect to the center.

[0024] Specific details of other embodiments are included in the detailed description and drawings.

[0025] According to the plastic stent according to an embodiment of the present invention,

[0026] First, the bending direction or angle of the anterior and posterior ends of a stent made of plastic material can be selectively applied, and

[0027] Second, by adjusting the magnitude of the restoring force, the rate of bile duct damage or displacement can be minimized, and

[0028] Third, by providing a metal marker on the outer surface at a set location of the plastic stent, the position or direction of the stent can be clearly identified on an X-ray or endoscope, and

[0029] Fourth, by providing a flap at the tip or posterior end, the position of the stent can be easily fixed.

[0030] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0031] The summary described above, as well as the detailed description of the preferred embodiments of the present application described below, will be better understood when read in conjunction with the accompanying drawings. Preferred embodiments are illustrated in the drawings for the purpose of illustrating the invention. However, it should be understood that the present application is not limited to the exact arrangements and means illustrated.

[0032] FIGS. 1a to 1c are reference diagrams schematically illustrating the process of implanting a plastic stent according to the present invention.

[0033] FIG. 2 is a plan view illustrating a plastic stent according to a first embodiment of the present invention.

[0034] Figure 3 is a plan view illustrating the plastic stent shown in Figure 2.

[0035] Figures 4 and 5 are reference diagrams illustrating a delivery-integrated plastic stent.

[0036] Figure 6 is a reference diagram illustrating the unfolded state of the plastic stent shown in Figure 3.

[0037] Figures 7a and 7b are reference diagrams illustrating a comparison of the state in which a plastic stent is inserted as shown in Figure 6.

[0038] FIG. 8 is a plan view illustrating a plastic stent according to a second embodiment of the present invention.

[0039] FIG. 9 is a plan view illustrating a plastic stent according to a third embodiment of the present invention.

[0040] FIG. 10 is a plan view illustrating a plastic stent according to a fourth embodiment of the present invention.

[0041] Figure 11 is a captured image of a surgical scene illustrating the state of performing the plastic stent procedure shown in Figure 10.

[0042] Figure 12 is an X-ray image showing the state after the plastic stent procedure shown in Figure 10 is completed.

[0043] Figure 13 is an X-ray image showing whether the position of the mini pigs in groups 1 to 4 was maintained 4 weeks after the bile duct insertion.

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0045] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in the drawings.

[0046] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0047] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms.

[0048] The above terms are used solely for the purpose of distinguishing one component from another.

[0049] For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component.

[0050] The term "and / or" includes a combination of multiple related listed items or any of the multiple related listed items.

[0051] When it is stated that one component is "connected" or "joined" to another component, it should be understood that while it may be directly connected or joined to that other component, there may also be other components in between.

[0052] On the other hand, when it is stated that one component is "directly connected" or "directly coupled" to another component, it should be understood that there are no other components in between.

[0053] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention.

[0054] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0055] In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0056] Hereinafter, embodiments will be described in detail with reference to the attached drawings, provided that identical or corresponding components are given the same reference number regardless of the drawing symbols, and redundant descriptions thereof will be omitted.

[0057] FIGS. 1a to 1c are reference diagrams schematically illustrating the process of implanting a plastic stent according to the present invention.

[0058] Referring to Figures 1a to 1c, there are two main types of biliary stents: endoscopic stent implantation and percutaneous stent implantation. Generally, endoscopic stent implantation (ERCP) is performed, but percutaneous stent implantation through the skin-liver (PTBD) is also selected and performed.

[0059] Endoscopic biliary stenting (ERCP) is used as a diagnostic method for biliary and pancreatic duct diseases, but it is primarily performed to insert a stent for the treatment of biliary obstruction. Generally, ERCP is a procedure in which a blocked bile duct is opened through a lateral duodenoscope, and a drainage tube or stent is inserted into the widened area of ​​the stenosis.

[0060] In addition, percutaneous biliary stenting (PTBD) is a procedure in which a stent is inserted into the narrowed portion of the bile duct after accessing the intrahepatic bile duct through the skin and liver parenchyma, allowing bile to drain into the intestines via the normal pathway. PTBD is a procedure used to insert a stent through the abdominal wall from outside the skin when endoscopic stenting is difficult or has failed, and it is used as the primary treatment for biliary atresia.

[0061] Stents can be broadly classified into plastic and expandable metal materials. Each material has its advantages and disadvantages, and they can be selectively used depending on the patient's condition, surgical feasibility, and installation method; in this embodiment, a stent composed of plastic is described.

[0062] The biggest problem with stent procedures is the occlusion rate caused by bile sludge and tumor invasion, and various materials and structures are being developed to prevent this and increase the patency period of biliary stents.

[0063] Here, the endoscopic biliary stent procedure (ERCP) applied in this embodiment involves inserting an endoscope into the esophagus, stomach, or duodenum through the mouth after sedation, and inserting it into the bile duct or pancreatic duct along with a plastic stent using a thin tube-shaped catheter, and inserting it into the site of stenosis confirmed through cholangiography.

[0064] Bile produced in the liver is stored in the gallbladder and, when needed, flows through the bile duct into the duodenum (3) to aid in digestion as the gallbladder contracts, and pancreatic juice produced in the pancreas flows through the pancreatic duct into the duodenum (3) when needed to aid in digestion. The bile duct and the pancreatic duct meet at a single tube just before entering the duodenum and connect to the duodenum (3). The part exposed to the inner surface (1) of the duodenum as a single tube here is the duodenal papilla (4).

[0065] Endoscopic retrograde cholangiopancreatography is a test performed using an endoscope and radiation. An endoscope (11) is inserted into the duodenum (3), and a contrast agent is injected into the bile duct and pancreatic duct through the opening of the duodenal papilla (4), after which the structure of the bile duct and pancreatic duct and any abnormal lesions can be examined. In addition, endoscopic retrograde cholangiopancreatography not only confirms the structure and lesions of the bile duct and pancreatic duct, but also allows for the collection of specimens for tissue biopsy if necessary, and can also be used to remove bile duct stones, drain bile, or perform a stent (100) procedure to treat bile duct obstruction.

[0066] FIG. 2 is a plan view illustrating a plastic stent according to a first embodiment of the present invention, and FIG. 3 is a plan view illustrating the plastic stent shown in FIG. 2.

[0067] Referring to FIGS. 2 and 3, a plastic stent (100) according to a first embodiment of the present invention may include a tip portion (110), a center portion (120), and a rear portion (130). This plastic stent (100) may be formed as a single tube structure. Here, the tip portion (110) may be located in a first region (A1) positioned at the front of the plastic stent. Additionally, the center portion (120) may be located in a second region (A2) in the middle of the plastic stent. Furthermore, the rear portion (130) may be located in a third region (A3) positioned at the rear of the plastic stent. Here, the front and rear are defined for convenience of explanation, and their directions may differ depending on the direction of travel.

[0068] First, the tip (110) is the part where the plastic stent (100) first enters the duodenal papilla (see FIG. 1, 4), and can be formed in a half pigtail type that is bent in a curve from one side of the center (120).

[0069] An inlet (111) may be formed at one end of the tip portion (110). Additionally, a plurality of through holes may be formed on the outer surface of the tip portion (110). Bile or pancreatic fluid may be introduced into the inlet (111) and the through holes. The bile or pancreatic fluid introduced into the tip portion (110) in this manner may be delivered through an internal flow path that extends to the rear portion.

[0070] In the first embodiment of the present invention, the tip portion (110) may be bent in a range of about 180 to 270° from one end portion of the center (120). That is, when it reaches 180° relative to a virtual extension line extending from one side of the center (120), it may be positioned to face in the opposite direction to the center (120), and FIGS. 2 and 3 illustrate, as an example, that it is bent in a range of about 220 to 230°.

[0071] At this time, it is preferable that the tip portion (110) be positioned so as not to overlap with the other end portion or the center portion (120). When the tip portion (110) is bent, it unfolds into an almost straight shape upon entry into the bile duct, and then settles into place along the shape of the bile duct due to elastic restoring force.

[0072] The tip portion (110) may have a first marker (112) provided at a set position adjacent to the inlet (111).

[0073] The first marker (112) is provided in the shape of a ring made of metal and can be positioned to surround the outer surface of the tip portion (110). The first marker (112) can be coupled or attached to the tip portion (110), or it can be integrally mounted through double injection molding during the molding process of the tip portion (110).

[0074] The first marker (112) is preferably made of a metal material that is free of harmful substances in the body and has excellent corrosion resistance, and can contribute to determining the accurate location of the tip (110) during X-ray imaging. Of course, it can be used to check the degree of bending of the tip (110) on the plastic stent (100).

[0075] Although not illustrated in the drawing, the first marker (112) may be provided in the shape of multiple separate rings. When the first marker is provided in the shape of rings and arranged in multiple numbers, for example, when a set number of first markers are placed at the leading edge (110), it is predicted that the position of the leading edge (110) can be quickly identified through the set number of first markers during X-ray imaging. For example, if the first marker at the leading edge (110) is composed of one relatively thick ring, and the other marker provided at the center (120) is provided with two or three relatively thin rings, the positions of the leading edge (110) and the trailing edge (130) can be quickly identified through X-ray imaging.

[0076] The tip portion (110) may have a first flap (113) provided adjacent to the first marker (112).

[0077] The first flap (113) may be a structure that is bent so as to protrude from the outer surface by peeling off a part of the outer surface of the tip portion (110).

[0078] Although not shown in the drawing, the first flap (113) may be provided in a structure that is separately attached without peeling off the outer surface of the tip portion (110). In this case, the first flap (113) may include a ring member (not shown) attached to the outer surface of the tip portion (110) and a flap member (not shown) that is bent from the ring member and protrudes away from the outer surface of the tip portion.

[0079] The first flap (113) can fix the position of the tip (110) when the plastic stent (100) is positioned at the set installation location. For example, the first flap (113) can restrict the movement or rotation of the tip (110) inside the bile duct.

[0080] Additionally, the central part (112) provides a passage connecting the front end (110) on one side and the rear end (130) on the other side, and can maintain a roughly straight shape.

[0081] The length of the center (120) can be selectively adjusted according to gender or age.

[0082] A second marker (121, 122) may be provided at one end and the other end of the center (120).

[0083] The second marker (121, 122) may be made of a metal material to wrap around the outer surface in the area between the center (120) and the front end (110) and in the area between the center (120) and the rear end (130).

[0084] The second marker (121, 122) is placed at a position distinct from the first marker (112) and can identify the center position of the plastic stent (100).

[0085] As described above, the second marker (121, 122) may be represented with a shape or thickness different from that of the first marker (112). In FIGS. 2 and 3, the first marker (112) and the second marker (121, 122) are represented with the same shape and thickness, but are not limited thereto.

[0086] Additionally, although not shown in the drawing, if the structure is such that the second marker (121, 122) is wound around the outer surface of the center (120), a groove (not shown) may be formed along the outer surface of both ends of the center (120) to which the second marker (121, 122) is to be joined, so as to correspond to the thickness of the second marker (121, 122). That is, the outer surface of the second marker (121, 122) and the outer surface of the center (120) may be formed so as not to protrude by the thickness of the second marker (121, 122) on the outer surface of both ends of the center (120), and so as to match with the same diameter.

[0087] And, the rear end (130) may have an outlet (131) located at the end of the flow path. That is, the plastic stent (1100) has a single flow path formed from the inlet (111) to the outlet (131), so that bile or pancreatic fluid can be discharged through the outlet (131) as it flows in from the front end (110). Here, at least the outlet (131) of the rear end (130) may be exposed inside the duodenum (see FIG. 1, 3).

[0088] The rear end (130) may be formed in a roughly pig tail shape. That is, the rear end (130) may have an area formed where the end overlaps with the rear end (130) or the center (120) at least once. Accordingly, the rear end (130) may have a stronger restoring force than the front end (110).

[0089] Additionally, a through hole with the same structure as the through hole of the front end (110) may be formed in the rear end (130).

[0090] FIGS. 4 and 5 are reference diagrams illustrating a delivery-integrated plastic stent, and FIG. 6 is a reference diagram illustrating the plastic stent shown in FIG. 3 in an unfolded state.

[0091] Referring to FIGS. 4 to 6, a delivery-integrated plastic stent (200) may have a first locking groove (114) formed at the tip (110) or the rear end. In this embodiment, the first locking groove (114) is formed adjacent to the inlet (111) of the tip (110) as an example.

[0092] The first locking groove (114) can be formed by cutting about 1 / 3 to 1 / 2 of the diameter along the outer surface of the tip portion (110) so that the internal flow path is exposed on the outer surface. At this time, the first locking groove (114) is positioned to correspond to the second locking groove (14) of the same shape formed in the catheter (13), and the first locking groove (114) and the second locking groove (14) can be joined so as to interlock with each other.

[0093] As illustrated in FIG. 5, an inner sheath (12) penetrating the interior of the catheter (13) is provided inside the catheter (13), and when the inner sheath (12) enters the flow path of the plastic stent (200) after the first locking groove (114) and the second locking groove (14) are joined, the connection force between the plastic stent (200) and the catheter (13) can be maintained. At this time, the position of the plastic stent (200) can be selectively adjusted while moving the catheter (13).

[0094] For example, the catheter (13) and the tip (110) may be connected, or the catheter (13) and the rear end may be connected to adjust the position of the plastic stent (200).

[0095] When the position adjustment of the plastic stent (200) is completed, the inner sheath (12) can be discharged from inside the catheter (13) to the outside, thereby releasing the connection between the first locking groove (114) and the second locking groove (14).

[0096] Referring to Fig. 6, the plastic stent shows a state in which an inner sheath is coupled inside.

[0097] The inner sheath (12) can be inserted into the internal flow path of the plastic stent (100) and can be optimized to pass through a narrow stenotic area (see FIG. 1, 2) within the bile duct.

[0098] In addition, since the plastic stent (100) can be maintained in a state where it is attached to the inner sheath (12), the inner sheath (12) can be moved to a desired position in the forward and backward directions along the direction in which the plastic stent (100) is inserted.

[0099] Figures 7a and 7b are reference diagrams illustrating a comparison of the state in which a plastic stent is inserted as shown in Figure 6.

[0100] FIG. 7a shows an x-ray image of a plastic stent (100) inserted according to the present invention, and FIG. 7b shows an x-ray image of a stent inserted according to the prior art.

[0101] Looking at FIG. 7a, it can be seen that the plastic stent (100) of the present invention is provided with a plurality of markers (112, 121, 122) made of metal material, so the position and direction of the plastic stent (100) can be clearly identified in an x-ray image.

[0102] In contrast, Fig. 7b retains the conventional problem that the marking on the stent cannot be identified in the x-ray image because it is drawn on the stent.

[0103] FIG. 8 is a plan view illustrating a plastic stent according to a second embodiment of the present invention.

[0104] Referring to FIG. 8, the plastic stent (200) according to the second embodiment of the present invention differs in the angle or direction of the tip portion (210). Reference numerals identical to those described above indicate identical components.

[0105] A plastic stent (200) according to a second embodiment of the present invention may include a tip portion (210), a center portion (120), and a rear portion (130).

[0106] Here, the tip portion (210) can be bent in a hook-type shape in the range of about 135 to 180° from one side of the center (120). That is, it can be bent at an acute angle of at least a right angle relative to a virtual extension line extending from one side of the center (120), and FIG. 8 illustrates an example of being bent at about 135°.

[0107] In this case, when the tip (210) is bent by about 135°, the restoring force can be relatively reduced compared to the tip (110) of the first embodiment described above.

[0108] Accordingly, there is an advantage in that a plastic stent can be selectively applied among the plastic stent (100) of the first embodiment and the plastic stent (200) of the second embodiment depending on the magnitude of the restoring force or the shape or location of the bile duct.

[0109] FIG. 9 is a plan view illustrating a plastic stent according to a third embodiment of the present invention.

[0110] Referring to FIG. 9, a plastic stent (300) according to a third embodiment of the present invention may include a tip portion (310), a center portion (120), and a rear portion (130).

[0111] Here, the leading edge (310) can be bent in a cross-sectional shape approximately "L" from one side of the center (120) at a range of about 90 to 135°. That is, the leading edge (310) of the third embodiment is exemplarily shown as being bent in a direction perpendicular to a virtual extension line extending from one side of the center (120).

[0112] In this case, when the tip (310) is bent about 90°, there is an advantage of being able to relatively reduce the restoring force compared to the tip (210) of the second embodiment described above.

[0113] FIG. 10 is a plan view illustrating a plastic stent according to a fourth embodiment of the present invention, FIG. 11 is a captured image of a procedure scene illustrating the state of performing the procedure on the plastic stent shown in FIG. 10, and FIG. 12 is an X-ray image showing the state after the procedure on the plastic stent shown in FIG. 10 is completed.

[0114] Referring to FIGS. 10 to 12, a plastic stent (400) according to the fourth embodiment of the present invention may include a tip portion (110), a center portion (120), and a rear portion (430).

[0115] Here, the leading portion (110) has the same structure as the leading portion (110) of the first embodiment described above, and there is a difference in the structure of the trailing portion (430).

[0116] The rear end (430) can be formed as a half band type, unlike the pigtail type of the first embodiment.

[0117] The rear end (430) of the half-band type provides a structure that is bent by about 50% compared to the pigtail type, and can be bent in a range of about 30 to 70° from the other side of the center (120), and thus has the advantage of significantly reducing the restoring force.

[0118] FIG. 10 illustrates an exemplary state in which the stent is bent at approximately 70°. Since this half-band type rear end (430) structure reduces the restoring force, it has the effect of preventing bile duct damage and stent displacement caused by the relatively large restoring force of the pigtail type described above.

[0119] Of course, a plastic stent (400) having a half-band type rear end (430) can maintain the same amount of artificial bile drainage and allows for the relocation of the procedure site, so the effect of increased applicability or versatility can also be expected.

[0120] And, the rear end (430) may include a second flap (432) provided on the outer surface of the rear end adjacent to the discharge port (431).

[0121] The second flap (432) is identical in shape and function to the first flap (113) provided at the tip (110), and provides the same effect in terms of effectiveness, so a redundant description is omitted.

[0122] In addition, as shown in Fig. 11, since the rear end of the plastic stent is of the half-band type, the possibility of perforation can be significantly reduced during the process of adjusting or moving the position of the plastic stent.

[0123] For example, if the rear end (430) has a slight change in angle or direction from the center (120) or is formed in a pigtail type, damage to the bile duct or duodenum or perforation may occur during the process of moving the stent. However, in the case of a structure bent into a roughly "J" shape, such as the rear end of the fourth embodiment, there is an advantage in that the possibility of bile duct damage or perforation can be significantly reduced.

[0124] Although not shown in the drawing, the rear end (430) structure of the half-band type can also be applied to the front end (110). For example, the front end (110) can be bent in a range of about 30 to 70° from one side of the center (120).

[0125] Accordingly, according to the plastic stent of the embodiment of the present invention, the bending direction or angle of the anterior and posterior ends of the stent made of plastic material can be selectively applied, and the rate of bile duct damage or displacement can be minimized by adjusting the magnitude of the restoring force, and the position or direction of the stent can be clearly identified on an X-ray or endoscope by providing a metal marker on the outer surface at a set position of the plastic stent, and the position of the stent can be easily fixed by providing a flap at the anterior or posterior end.

[0126] The following experimental examples are intended to more easily explain the effects of the present invention, and the present invention is not limited thereto.

[0127] [Experimental Example 1 - In vitro evaluation of mechanical performance of plastic stent]

[0128] In this experimental example, in order to evaluate the mechanical performance of a plastic stent according to an embodiment of the present invention, a total of four types of stents with different structures were fabricated, and the mechanical properties of each were tested.

[0129] A total of four types of stents were designed identically with an outer diameter of 7 Fr and a length of 7 cm, and their specific structures are as follows.

[0130] - Group 1 (Control): No flaps, no markers

[0131] - Group 2 (Comparative Example 1): Presence of tip flap, tip fold structure, presence of marker

[0132] - Group 3 (Comparative Example 2): Rear flap present, rear folded structure, marker present

[0133] - Group 4 (one embodiment of the present invention): flaps at the leading and trailing ends, folded structure at the leading and trailing ends, markers present

[0134] Mechanical properties tests were conducted using ASTM-based mechanical testing equipment, and the test items included retention strength, resilience, bending strength, buckling force, and pinch friction.

[0135] The retention strength item measured the maximum axial resistance required of the stent during the process of maintaining its position or removing it within the bile duct where it was inserted. As a result of the measurement, Group 4 exhibited lower retention force compared to Groups 1 to 3, confirming that the risk of tissue damage during removal from the bile duct is reduced and the operator's operational burden can be alleviated.

[0136] The resilience item quantitatively measured and analyzed the tendency of the stent to return to its original shape after an external force was applied. As a result of the measurement and analysis, groups 1 to 3 exhibited high resilience, which caused significant resistance at the insertion route and could lead to tissue damage during insertion, whereas group 4 maintained appropriate resilience while preventing excessive rebound, thereby minimizing irritation to the bile duct wall.

[0137] Bending strength was measured by applying a bending load to the center of the stent to determine the maximum strength. This bending strength is a key criterion for assessing the flexibility and procedural suitability of the stent during biliary insertion. As a result of the measurement, Group 4 showed the lowest bending strength compared to Groups 1 through 3, which implies the securing of flexibility to smoothly respond to complex anatomical pathways.

[0138] The buckling force item measured the resistance to buckling, a phenomenon where the stent collapses or compresses inward when subjected to external pressure. As a result of the measurement, it was confirmed that Group 4 maintained buckling resistance for a specified period of time, thereby ensuring the patency of the drainage pathway for a long period.

[0139] The pinch friction item measured the coefficient of friction between the outer surface of the stent and the inner surface of the catheter or the pusher system. As a result of the measurement, it was confirmed that in Group 4, the internal and external friction forces are properly controlled due to the influence of the flap and bending structure, enabling smooth movement during insertion and removal into the body and preventing unnecessary migration.

[0140] Ultimately, Group 4 demonstrated excellent characteristics in terms of ease of insertion, anatomical compliance, minimization of biliary wall irritation, and maintenance of drainage function.

[0141] [Experimental Example 2 - Evaluation of an In vivo Animal Model of Biliary Stenosis]

[0142] To evaluate structural stability and histological response in the condition of biliary stenosis, a preclinical animal study was conducted using miniature pigs (approx. 30 kg). A total of 16 animals were subjected to radiofrequency ablation (RFA) to induce a stenotic lesion in the common bile duct. After inserting Group 4, stent displacement, histological response (inflammation, fibrosis, epithelial damage, etc.), the degree of sludge and biofilm formation, and luminal patency were evaluated during a 4-week observation period.

[0143] Figure 13 is an X-ray image showing whether the position of the mini pigs in groups 1 to 4 is maintained 4 weeks after insertion of the bile duct. For reference, Figure 13A is a photo of Group 1 inserted, Figure 13E is a photo 4 weeks after insertion of Group 1, Figure 13B is a photo of Group 2 inserted, Figure 13F is a photo 4 weeks after insertion of Group 2, Figure 13C is a photo of Group 3 inserted, Figure 13G is a photo 4 weeks after insertion of Group 3, Figure 13D is a photo of Group 4 inserted, and Figure 13H is a photo 4 weeks after insertion of Group 4.

[0144] Referring to Figure 13, Group 4 showed no instances of dislodgement from the insertion site in the mini pig's bile duct, and the tissue response score was observed to be significantly lower compared to Groups 1 to 3. Additionally, lymphocyte infiltration or epithelial damage was rarely observed throughout the entire insertion section, and scanning electron microscopy (SEM) confirmed that the lumen diameter remained widest and sludge accumulation occurred minimally.

[0145] [Experimental Example 3 - Clinical Application]

[0146] When Group 4 was applied to patients with bile duct stenosis that occurred after liver transplantation, the instability of the insertion site and bile duct distension that occurred with the use of conventional stents were resolved, and clinical efficacy was confirmed in that the shape and position of the stent remained stable in imaging after 3 months.

[0147] Although specific embodiments have been illustrated and described above to exemplify the technical concept of the present invention, the present invention is not limited to the configuration and operation identical to the specific embodiments described above, and various modifications may be implemented within the scope of the present invention. Accordingly, such modifications should also be considered to fall within the scope of the present invention, and the scope of the present invention should be determined by the claims set forth below.

Claims

1. A tip portion formed in a tube shape with an inlet formed on one side; A central part on one side extending integrally with the aforementioned tip; and A rear end portion integrally extended from the other side of the central portion and having an outlet formed at the end of a flow path communicating from the inlet; comprising A plastic stent in which the anterior and posterior ends provide different restoration angles or restoration forces based on the above-mentioned center.

2. In Paragraph 1, The above tip portion is, A plastic stent formed as a hook type or half pigtail type bent from one side of the above-mentioned center.

3. In Paragraph 2, The above tip portion is, A first restoration angle formed in the range of 30 to 70° from one side of the above-mentioned center, and A second restoration angle formed in the range of 90~135°, and A third restoration angle formed in the range of 135~180° and A plastic stent formed with any one of the fourth restoration angles formed in the range of 180~270°.

4. In Paragraph 1, The above rear end is, A plastic stent formed in a twisted pigtail type so as to overlap each other at least once.

5. In Paragraph 1, The above rear end is, A plastic stent formed into a half-pigtail type that is bent so as not to overlap each other.

6. In Paragraph 1, The above tip portion is, A plastic stent made of a metal material and comprising a first marker arranged to surround the tip portion adjacent to the inlet.

7. In Paragraph 1, A plastic stent made of a metal material and including second markers provided at both ends of the central portion.

8. In Paragraph 1, The above tip portion is, A plastic stent comprising a first flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the tip portion.

9. In Paragraph 1, The above rear end is, A plastic stent comprising a second flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the rear end.

10. In Paragraph 1, The above-mentioned front or rear end is provided with a first catch groove formed by cutting a part of the outer surface adjacent to the inlet or outlet, and A plastic stent whose position is adjusted by a catheter coupled to the first locking groove.

11. A tip portion formed in a tube shape with an inlet formed on one side; A central part having one side formed in a tube shape integrally with the aforementioned tip; A rear end formed integrally in a tube shape on the other side of the above central portion and having an outlet formed that communicates with the inlet; and A marker portion provided to wrap the outer surface of a metal material at least one or more of the above-mentioned front portion, center portion, and rear portion; A plastic stent containing 12. In Paragraph 11, The above marker part is, A first marker positioned adjacent to the inlet of the tip portion and arranged to surround the outer surface of the tip portion, and A plastic stent comprising a second marker disposed at both ends of the central portion and arranged to surround the outer surface of the central portion.

13. In Paragraph 11, The aforementioned front and rear ends are, A plastic stent that provides different restoration angles or restoring forces based on the above-mentioned center.

14. In Paragraph 11, The above tip portion is, A first restoration angle formed in the range of 30 to 70° from one side of the above-mentioned center, and A second restoration angle formed in the range of 90~135°, and A third restoration angle formed in the range of 135~180° and A plastic stent formed with any one of the fourth restoration angles formed in the range of 180~270°.

15. In Paragraph 11, The above tip portion is, A plastic stent comprising a first flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the tip portion.

16. In Paragraph 11, The above rear end is, A plastic stent comprising a second flap that is bent to protrude from the outer surface by peeling off a portion of the outer surface of the rear end.

17. In Paragraph 11, The above tip is provided with a catch groove formed by cutting a part of the outer surface adjacent to the inlet, and A plastic stent whose position is adjusted by a catheter coupled to the above-mentioned catch groove.

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