JP2019076121A - Stent - Google Patents

Abstract

To provide a stent capable of securing radial force required for maintaining an expanded state of an organism lumen while improving passing into the organism lumen.SOLUTION: A stent 200 includes a plurality of ring parts 210, and a connection part 220. The ring part arranged at least at a distal end among the plurality of ring parts has a nearly elliptical outer shape including a long axis along a first axis D1 inclined to a vertical axis Y, and a short axis along a second axis D2 orthogonal to the first axis, in a state that the stent 200 is contracted. An angle made by an interval between the vertical axis and the first axis becomes smaller with expansion and deformation of the stent 200 from the contracted state.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a stent.

  In order to treat various diseases caused by narrowing or occlusion of a lumen such as a blood vessel, a stent is placed in a living lumen to expand a lesion such as a stenosis or occlusion to secure the lumen. Medical device used to

  For example, Patent Document 1 discloses a stent that is configured to be contractible and expandable, including a linear strut that forms a cylindrical outer periphery, and a connecting portion that connects the struts.

  When placing a stent in a living lumen, the stent is delivered to a lesion in a contracted state, and the stent is expanded and placed at the lesion. The stent needs a radial force (expanded holding force) to maintain the expanded state in the living body lumen. In order to improve the radial force of the stent, for example, it is conceivable to increase the thickness of the struts or increase the number of struts.

JP 2009-537192 No.

  However, increasing the thickness of the struts or increasing the number of struts increases the profile (cross-sectional shape) of the stent in the contracted state, and the passage of the stent into the lumen of the living body decreases. .

  Therefore, an object of the present invention is to provide a stent capable of securing the radial force necessary to maintain the expanded state in the living body lumen while improving the passageability into the living body lumen. .

  The stent of the present invention for achieving the above object is a stent which is disposed in a contracted state around the outer periphery of a contractible expandable balloon, and is a stent which expands as the balloon expands, and is formed by an annular linear member A plurality of ring portions that form an outer periphery of a tubular shape by being arranged along the axial direction of the balloon, and a connecting portion that connects adjacent ones of the ring portions. The ring portion disposed at the tip of the plurality of ring portions has a major axis along a first axis inclined with respect to a vertical axis orthogonal to the axial direction of the balloon in a contracted state of the stent; And a short axis along a second axis orthogonal to the first axis, and having a substantially elliptical outer shape, wherein the ring portion is formed of an angle between the vertical axis and the first axis, The stent is formed so as to become smaller as it expands and deforms from its contracted state.

  Since the stent having the above configuration has a tapered shape toward the tip in the contracted state, the profile of the tip can be smaller than that of a cylindrical stent. In addition, as the stent expands and deforms, the angle formed between the vertical axis and the first axis in the ring decreases, and the stent moves in a direction perpendicular to the axial direction of the balloon. The radial force of the As a result, the stent having the above-described configuration is required to maintain the expanded state of a lesion such as a constricted part in the expanded state while improving the passageability into the living body lumen in the contracted state. Radial force can be secured.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the stent delivery system which concerns on embodiment. (A) shows the balloon and the stent in a contracted state, and (B) shows the balloon and the stent shown in (A) rotated 90 degrees around the axis of the stent. It is the expanded view which cut | disconnected and developed a part of outer periphery of the stent in the contracted state linearly along the axial direction. FIG. 2A is a view from the same direction as FIG. 2A, and FIG. 2B is a view from the same direction as FIG. 2B. It is. It is a top view for demonstrating the shape of the ring part of the stent which concerns on embodiment, (A) shows the ring part of the contracted state, (B) shows the ring part of the expanded state. It is a schematic diagram for demonstrating the structure of the ring part which concerns on embodiment, (A) shows the stent of the contracted state, (B) shows the stent of the expanded state. It is the schematic which shows the example of use of the stent which concerns on embodiment, and a stent delivery system, (A) is a figure which shows a mode that a stent delivery system is delivered to the stenosis part, (B) is a balloon and a stent. (C) is a figure which shows the state which indwelled the stent in the narrowing part.

  Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. The following description does not limit the technical scope or the meaning of terms described in the claims. Also, the dimensional proportions of the drawings are exaggerated for the convenience of the description, and may differ from the actual proportions.

  The stent 200 according to the present embodiment is a so-called balloon-expandable stent which is disposed in a contracted state around the outer circumference of the contractible-expandable balloon 120 and is expanded (plastically deformed) by the expansion force of the balloon 120.

  In this embodiment, a stent delivery system comprising a balloon catheter 100 and a stent 200 in order to deliver the stent 200 to a lesion such as a blood vessel, bile duct, trachea, esophagus, urethra, or other constriction in a living lumen. Use 10. The stent delivery system 10 delivers the stent 200 in a contracted state to the lesion, expands the stent, and places it in the lesion.

  The configuration of each part of the stent delivery system 10 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  In the present specification, the side to be inserted into the living body is referred to as “distal end” or “distal end side”, and the hand side operated by the operator is referred to as “proximal end” or “proximal side”. The distal end means a certain range including the distal end (the most distal end) and the periphery thereof, and the proximal end means a certain range including the proximal end (the most proximal end) and the periphery thereof.

  As shown in FIG. 1, the balloon catheter 100 comprises an elongated shaft 110, a deflation-expandable balloon 120 provided on the distal end side of the shaft 110, and a hub 130 fixed to the proximal end of the shaft 110. Have.

  As shown in FIG. 2A, the shaft 110 includes an outer tube 111 which is a tubular body having an open distal end and a proximal end, and an inner tube 112 disposed inside the outer tube 111.

Between the outer pipe 111 and the inner pipe 112, an expansion lumen through which an expansion fluid for expanding the balloon 120 flows is formed. Inside the inner tube 112, a lumen for a guide wire through which a guide wire W for guiding the balloon 120 to the lesioned part is inserted is formed. The expansion fluid may be gas or liquid, and examples thereof include gases such as helium gas, CO ₂ gas, O ₂ gas, and liquids such as physiological saline and contrast medium.

  In the balloon catheter 100 according to the present embodiment, as shown in FIG. 1, the guide wire W is inserted into the inner tube 112 through the opening 113 formed on the way between the distal end side and the proximal end side of the shaft 110. It is configured as a so-called rapid exchange catheter to be introduced. However, the balloon catheter 100 may be configured as a so-called over-the-wire type catheter.

  The distal end portion of the inner tube 112 penetrates the inside of the balloon 120 and is opened distal to the balloon 120. As shown in FIG. 2A, contrast markers 114a and 114b are provided in the inner tube 112.

  The outer pipe 111 and the inner pipe 112 are preferably formed of a material having a certain degree of flexibility, and examples of such materials include polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-acetic acid Polyolefins such as vinyl copolymer, ionomer, or a mixture of two or more of them, polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, thermoplastic resin such as fluorocarbon resin, silicone rubber, latex rubber, etc. Can be mentioned.

  The balloon 120 pushes the stent 200 from the inner side to expand it. The proximal end of the balloon 120 is fixed to the distal end of the outer tube 111, and the distal end of the balloon 120 is fixed to the distal end of the inner tube 112.

  The balloon 120 is preferably formed of a material having a certain degree of flexibility, for example, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or two of them. Polyolefins such as the above mixture, soft polyvinyl chloride resins, polyamides, polyamide elastomers, polyesters, polyester elastomers, polyurethanes, polyurethane resins, thermoplastic resins such as fluorocarbon resins, silicone rubbers, latex rubbers, etc. can be used.

  The hub 130, as shown in FIG. 1, includes a proximal opening 131 which functions as a port for the inflow and outflow of the expansion fluid. The proximal end opening 131 communicates with the expansion lumen formed in the outer tube 111.

  Examples of the constituent material of the hub 130 include thermoplastic resins such as polycarbonate, polyamide, polysulfone, polyarylate, methacrylate-butylene-styrene copolymer and the like.

  The stent 200 has a hollow tubular shape. The stent 200 has a plurality of ring portions 210 that form the outer periphery of a tubular shape, and a connecting portion 220 that connects adjacent ring portions 210 with each other. The ring portion 210 is formed by an annular linear member 201, and is arranged at intervals along the axis X direction of the tubular shape. The axial direction X of the tubular shape is the same as the axial direction of the balloon 120.

  In the present specification, the tube-shaped axis formed by the ring portion 210 is simply described as “axis X”, and the axis X perpendicular to the tube-shaped axis X, that is, the axis perpendicular to the axis of the balloon 120 is simply “vertical axis Write "Y". In addition, the circumferential direction around the axis X of the tube shape is simply described as “circumferential direction C” (see FIG. 5A), and the radial direction of the ring portion 210 is simply described as “radial direction R” (see FIG. 5 (A)).

  The stent 200 is held on the outer periphery of the balloon 120 in a contracted state, as shown in FIGS. 1 and 2. When the balloon 120 is expanded, the balloon 120 is expanded as the balloon 120 is expanded, as shown in FIG.

  Here, the “shrinkage state” of the stent 200 indicates that the stent 200 is placed so as to cover the outer periphery of the balloon 120 before being expanded, and is then compressed under pressure to be crimped. Also, the “expanded state” of the stent 200 indicates the expanded state as the expanded balloon 120 is expanded until the internal pressure reaches the recommended expanded pressure. The recommended expansion pressure may be appropriately changed according to the product specifications (for example, the outer diameter, the application, etc.) of the balloon 120 and the stent 200, but can be set to 8 atm to 12 atm, for example.

  The ring portion 210 disposed at the tip of the plurality of ring portions 210 has a first inclination inclined with respect to the vertical axis Y in plan view as shown in FIG. 5A in a state where the stent 200 is contracted. And a short axis along a second axis D2 orthogonal to the first axis D1, and a substantially elliptical outer shape. The ring portion 210 is preferably formed symmetrically with respect to each of the first axis D1 and the second axis D2.

  Here, “in a plan view” means a direction perpendicular to the plane formed by the annular outline formed by the linear members 201 forming the ring portion 210 (arrows P in FIGS. 2A and 4). Shows a plan view seen from the direction The ring portion 210 is not limited to the case where the annular outer shape formed by the linear members 201 is on the same plane, and may be formed three-dimensionally in the depth direction of FIG. 5.

  As shown in FIG. 6A, in the contracted state of the stent 200, an angle θ1 formed between the vertical axis Y and the first axis D1 can be, for example, 30 to 60 degrees.

  In the present embodiment, not only the ring portion 210 disposed at the extreme end, but all the ring portions 210 have a substantially elliptical outer shape in a state where the stent 200 is contracted, and the first axis D1 of each is It is inclined with respect to the vertical axis Y.

  In the plurality of ring portions 210, preferably, the angles θ1 formed between the vertical axis Y and the first axis D1 are the same. Moreover, it is preferable that the direction of the circumferential direction C mutually corresponds with the several ring part 210. As shown in FIG. That is, along the axial direction of the balloon 120, it is preferable that the plurality of ring portions 210 be provided in parallel with each other.

  As shown in FIG. 2 (B), FIG. 3 and FIG. 5 (A), the top portion 211 of the substantially elliptical shape in the major axis direction is curved to be folded inward from the outline of the substantially elliptical shape And a folding portion 212. Note that “folding back inward from the outline of the substantially elliptical shape” is not limited to a configuration in which the ring portion 210 is folded back inward in the radial direction R as shown in FIG. 5A, and the folding direction is It may be inclined with respect to the direction along the radial direction R inward.

  In the present specification, the “substantially elliptical shape” is not limited to the elliptical shape, but includes a wide longitudinal shape formed by a line passing through the end point of the major axis and the end point of the minor axis. As in the present embodiment, a shape in which the top portion 211 of the elliptical shape is provided with the folded portion 212 is also included in the substantially elliptical shape.

  Referring to FIG. 5A, the ratio (L2 / L1) of the length L2 along the second axis D2 to the length L1 along the first axis D1 of the stent 200 is a value of less than one. Although the said ratio (L2 / L1) will not be specifically limited if it is a value of less than 1, For example, it can be set as 0.4-0.8.

  The connecting portion 220 is provided between a straight portion 221 parallel to the first axis D1 of the adjacent ring portions 210, and between the straight portion 221 and the ring portion 210, as shown in FIG. It has a distal end side curved portion 222a and a proximal end side curved portion 222b (curved portion) convexly curved in a direction in which the ring portion 210 and the linear portion 221 extend. The distal end side curved portion 222a is connected to the distal end side ring portion 210, and the proximal end side curved portion 222b is connected to the proximal end side ring portion 210. Thereby, when the distance between the ring portion 210 and the linear portion 221 is reduced at the time of crimping of the stent 200, the distal end side curved portion 222a and the proximal end side curved portion 222b are prevented from contacting the ring portion 210, and the stent 200 can be sufficiently The diameter can be reduced.

  In the present embodiment, as shown in FIG. 3, the distal end side curved portion 222 a is disposed on the distal end side ring portion 210 with reference to an extension line 221 a that is an extension of a straight line along the linear portion 221. The portion 222 b is disposed on the proximal end side ring portion 210 side.

  The dimension of the folded portion 212 of the ring portion 210 and the ratio of the length L2 along the second axis D2 to the length L1 along the first axis D1 take into consideration the relationship with the recommended expansion pressure of the balloon 120, etc. Can be set to any value.

  In use of the stent delivery system 10, when the expansion fluid is injected into the balloon 120 and expanded, as shown in FIGS. 4 and 5 (B), the stent 200 is radially oriented along with the deformation of the balloon 120. R Expand and deform outward. As the stent 200 is expanded and deformed from the contracted state, the ring portion 210 is deformed so that the first axis D1 rises in the vertical axis Y direction as shown in FIG. 6 (B). At this time, as the folded portion 212 is deformed outward in the radial direction R, the apex 211 is likely to spread in the direction along the second axis D2. Thereby, the ring portion 210 is deformed so that the amount of deformation in the direction along the second axis D2 becomes larger than the amount of deformation in the direction along the first axis D1, as shown in FIG. 5B. As shown, the outer shape of the ring portion 210 is easily deformed so as to approach a perfect circular shape.

  5 (B), in the expanded state of the stent 200, a ratio (L22 / L12) of the length L22 along the second axis D2 to the length L12 along the first axis D1 is the stent 200. Is larger than the ratio of contracted states (L2 / L1).

  When the outer shape of the ring portion 210 is a perfect circle, the length L12 along the first axis D1 is equal to the length L22 along the second axis D2, and the first length L12 along the first axis D1 The ratio of the length L22 along the axis D2 of 2 (L22 / L12) is 1.

  When the stent 200 is expanded, an angle θ2 between the vertical axis Y and the first axis D1 shown in FIG. 6B is the vertical axis Y in the contracted state of the stent 200 shown in FIG. Is smaller than an angle θ1 formed between the first axis D1 and the first axis D1.

  In the present embodiment, in the expanded state of the stent 200, the ring portion 210 forms an angle θ2 between the vertical axis Y and the first axis D1 of 0 (zero) degrees, ie, perpendicular to the first axis D1. It deforms so as to rise to a position where it overlaps with the axis Y.

  As a material which comprises the stent 200, the metal which has biocompatibility is preferable, For example, iron base alloys, such as stainless steel, tantalum (tantalum alloy), platinum (platinum alloy), gold (gold alloy), cobalt chromium alloy etc. Cobalt-based alloys, titanium alloys, niobium alloys and the like. In addition, the stent 200 may be, for example, a biodegradable stent composed mainly of a polymer or the like, and the material is not particularly limited as long as it is known as a balloon expandable stent.

  Next, with reference to FIG. 7, a procedure for expanding the constriction portion N formed in the blood vessel V using the stent 200 according to the present embodiment will be described by taking a procedure performed using the stent delivery system 10 as an example. .

  First, as shown in FIG. 7A, the balloon 120 in a state of holding the stent 200 is delivered to the narrowed portion N along the guide wire W disposed in the blood vessel V prior to the introduction of the balloon catheter 100. At this time, the ring portion 210 of the stent 200 is held by the balloon 120 in a contracted state. The ring portion 210 disposed at the forefront has a substantially elliptical outer shape in a contracted state, and its first axis D1 is inclined with respect to the vertical axis Y. For this reason, the distal end of the stent 200 has a tapered shape toward the distal end. Thereby, the passage of the stent 200 into the blood vessel V can be improved. Further, in the present embodiment, not only the most distal ring portion 210 but also all the ring portions 210 have a substantially elliptical outer shape, and the first axis D1 thereof is inclined with respect to the vertical axis Y. . As a result, the profile of the entire stent 200 is reduced, and thus the passage into the blood vessel V can be further improved.

  Next, as shown in FIG. 7 (B), after the balloon 120 is placed at the narrowed portion N, the balloon 120 is expanded. As the balloon 120 expands, the stent 200 expands so as to spread toward the stenosis N and is crimped to the stenosis N. At this time, the ring portion 210 is deformed so that the angle formed between the vertical axis Y and the first axis D1 of the ring portion 210 becomes smaller, that is, it rises in a direction perpendicular to the axial direction of the balloon 120. Furthermore, the outer shape of the ring portion 210 formed by the linear member 201 is deformed so as to approach a perfect circular shape. Therefore, since the radial force can be improved as compared with the case where the ring portion 210 has an elliptical shape and the first axis D1 is inclined with respect to the vertical axis Y, the expanded state of the narrowed portion N is maintained. It is possible to secure the necessary radial force.

  Next, as shown in FIG. 7C, the balloon 120 is contracted, the balloon catheter 100 and the guide wire W are removed outside the body, and the stent 200 in the expanded state is indwelled in the narrowed portion N. Finish. Thus, the expanded state of the narrowed portion N can be maintained.

  As described above, in the stent 200 according to the present embodiment, the ring portion 210 disposed at the tip of the plurality of ring portions 210 in the contracted state of the stent 200 is orthogonal to the axial X direction, that is, the axial direction of the balloon 120 It has a substantially elliptical outer shape including a major axis along a first axis D1 inclined with respect to the vertical axis Y, and a minor axis along a second axis D2 orthogonal to the first axis D1. In addition, the angle formed between the vertical axis Y and the first axis D1 of the ring portion 210 is formed to be smaller as the stent 200 is expanded and deformed from the contracted state.

  According to the stent 200 configured as described above, the stent 200 has a tapered shape toward the tip in a state where the stent 200 is contracted. Thereby, the profile of the distal end portion of the stent 200 is reduced. In addition, as the stent 200 is expanded and deformed from the contracted state, the angle formed by the ring portion 210 between the vertical axis Y and the first axis D1 decreases, and the direction perpendicular to the axial direction of the balloon 120 is reduced. The radial force of the stent 200 is increased in response to the rising. In this manner, the stent 200 in the contracted state secures the passage to the living body lumen, while in the expanded state, the radial force necessary to maintain the expanded state of the lesion such as the constriction part. Can be held.

  Further, the ratio of the lengths L2 and L22 along the second axis D2 to the lengths L1 and L12 along the first axis D1 of the ring portion 210 is large as the stent 200 is expanded and deformed from the contracted state. Become. That is, since the outer shape of the ring portion 210 formed by the linear member 201 is deformed so as to approach a perfect circular shape as the expansion deformation is performed, the radial force can be improved.

  Further, at least one of the ring portions 210 disposed on the proximal side of the ring portion 210 disposed at the most distal end has a substantially elliptical outer shape in a state where the stent 200 is contracted. As a result, the profile on the proximal end side of the stent 200 as well as the distal end becomes smaller in the contracted state of the stent 200, thereby further improving the passage into the living body lumen.

  The ring portion 210 disposed at the distal end in a contracted state of the stent 200 and the ring portion 210 disposed proximal to the distal end and having a substantially elliptical outer shape in a contracted state have vertical axes. The angles θ1 formed between Y and the first axis D1 are the same, and the directions in the circumferential direction C coincide with each other. That is, the plurality of ring portions 210 are provided in parallel to one another along the axial direction of the balloon 120. As a result, since the plurality of ring portions 210 can be uniformly deformed as the stent 200 is expanded and deformed from the contracted state, the cross-sectional shape in the direction of the axis X of the stent 200 can be made uniform. . Thereby, the radial force of the entire stent 200 can be uniformly improved.

  Further, in a state in which the stent 200 is contracted, the ring portion 210 at least at the folding portion 212 configured to be curved so as to be folded inward from the substantially elliptical outer shape at the top portion 211 in the first axis D1 direction. I have one. As a result, the ring portion 210 can be deformed so as to approach a true circular shape relatively easily as the stent 200 is expanded and deformed from the contracted state, so that the radial force can be further improved. Thus, in the expanded state of the stent 200, the radial force necessary to maintain the expanded state of the narrowed portion can be held more reliably.

  Further, in a state in which the stent 200 is contracted, the linear portion 221 parallel to the first axis D1 of the adjacent ring portions 210, and between the linear portion 221 and the ring portion 210, is provided. The distal end side curved portion 222a and the proximal end side curved portion 222b are convexly curved in a direction in which the portion 221 extends. Thereby, when the stent 200 is crimped to the balloon 120, the distal end side curved portion 222a and the proximal end side curved portion 222b are prevented from contacting the ring portion 210, and the distance between the ring portion 210 and the linear portion 221 is sufficient. Can be reduced to Therefore, since the diameter of the stent 200 can be sufficiently reduced, the passability of the stent 200 into the living body lumen can be further improved.

  As mentioned above, although the stent which concerns on this invention was demonstrated through embodiment, this invention is not limited only to the structure demonstrated in embodiment, It is possible to change suitably based on the statement of a claim. .

  For example, although all the ring portions have a substantially elliptical outer shape in a contracted state of the stent, the present invention is not limited to this configuration, and only the ring portion disposed at the forefront among a plurality of ring portions It is sufficient if the shape has a substantially elliptical outer shape.

  Further, although the ring portion has been described as having a configuration in which the top portion of the link portion has one folded portion in a state where the stent is contracted, a plurality of folded portions may be provided on the top portion, or a configuration without a folded portion It may be When the configuration does not include the folded portion, for example, it is preferable that the ring portion be easily deformed into a perfect circular shape by reducing the curvature of the top.

10 stent delivery systems,
100 balloon catheters,
110 shaft,
120 balloons,
130 hubs,
200 stents,
201 linear members,
210 ring part,
211 top,
212 turn,
220 junctions,
221 straight part,
222a tip side curved portion (curved portion),
222b proximal curve (curved),
X-stent axis (tube-shaped axis),
Vertical axis of Y-stent (vertical axis of tube shape),
D1 first axis,
D2 second axis,
θ1, θ2 The angle between the vertical axis and the first axis.

Claims (6)

A stent disposed in a contracted state around the circumference of a contractible expandable balloon and expanding as the balloon expands,
A plurality of ring portions formed by an annular linear member and arranged along the axial direction of the balloon to form a tube-shaped outer periphery;
And a connecting portion connecting the adjacent ring portions,
The ring portion disposed at the most distal end of the plurality of ring portions has a long axis along a first axis inclined with respect to a vertical axis orthogonal to the axial direction of the balloon in a contracted state of the stent A substantially elliptical outer shape having a short axis along a second axis orthogonal to the first axis,
The stent, wherein the ring portion is formed such that an angle between the vertical axis and the first axis is reduced as the stent is expanded and deformed from a contracted state.   The ratio of the length along the second axis to the length along the first axis of the substantially elliptical shape increases as the stent is expanded and deformed from a contracted state. Stents.   The at least one of the plurality of ring portions disposed proximal to the ring portion disposed at the most distal end has the substantially elliptical outer shape in a contracted state of the stent. The stent according to claim 2.   The ring portion disposed at the most distal end, and the ring portion disposed proximal to the most distal end and having the substantially elliptical outer shape in a contracted state of the stent are arranged along the axial direction of the balloon. The stent according to claim 3, which is provided parallel to each other.   The ring portion having the substantially elliptical outer shape in a contracted state of the stent is curved at the apex in the first axial direction of the substantially elliptical shape so as to be folded inward from the substantially oval outer shape. The stent according to any one of claims 1 to 4, having at least one fold configured as above.   The connecting portion connected to the ring portion having the substantially elliptical outer shape in the contracted state of the stent includes a linear portion parallel to the first axis, the linear portion, and the ring portion. The stent according to any one of claims 1 to 5, further comprising a curved portion provided between and curved convexly in a direction in which the ring portion and the linear portion extend.