JP5770507B2 - Self-expanding stent and stent delivery system - Google Patents

Description

  The present invention relates to self-expanding stents and stent delivery systems.

  The stent delivery system is a medical device used to improve a stenosis or occlusion generated in a lumen in a living body, and has, for example, a sheath in which a self-expanding stent is housed on the inner surface of the distal end. The self-expanding stent is housed in the sheath in a contracted state, and after reaching the target site (stenosis or occlusion), it is released from the sheath to restore the shape before contraction.

  The self-expanding stent has a housing in which markers having contrast properties are arranged in order to improve the visibility during use (see, for example, Patent Document 1 and Patent Document 2).

JP 2008-086464 A JP 2003-334256 A

  However, the stent described in the above patent document has a large resistance when housed in the sheath and released from the sheath due to interference with the sheath of the housing in which the marker is arranged, and it is difficult to work smoothly. There is a problem that there is. This problem becomes more prominent as the diameter (outer diameter and inner diameter) of the stent is smaller and the shape of the stent strut becomes more complex and precise.

  The present invention has been made to solve the above-described problems associated with the prior art, and provides a self-expanding stent and a stent delivery system that can reduce resistance when housed in a sheath and when released from the sheath. Objective.

In order to achieve the above object, the present invention is a self-expanding stent that is housed in a sheath in a contracted state, reaches the target site, and is then released from the sheath to restore the shape before contraction. Te has a wavy strut, an opening marker is accommodated having a contrast property, and, having a housing which is placed on top of the corrugated struts. The length of the opening in the circumferential direction orthogonal to the axial direction of the stent is smaller than the length of the opening in the axial direction, and not more than one third of the length of the housing in the circumferential direction. It is.

  Another aspect of the present invention for achieving the above object is that the sheath and the shape before contraction are accommodated in the sheath in a contracted state, and are released from the sheath after reaching the target site. And a self-expanding stent which is restored to a stent delivery system.

  According to the present invention, the width of the opening in which the marker is accommodated (the length of the opening in the circumferential direction) is equal to or less than one third of the width of the housing (the length of the housing in the circumferential direction). When the expandable stent is housed in and released from the sheath, interference of the housing with the sheath, i.e., the housing being caught on the inner surface of the sheath, is suppressed. That is, even if there is an opening in which the marker is accommodated, resistance can be reduced because it can be accommodated in and released from the sheath while maintaining the curvature of the housing. Moreover, since the length of the opening part in the axial direction is larger than the width of the opening part, it is possible to secure the area of the opening part (marker size) and maintain the contrast of the marker. Therefore, it is possible to provide a self-expanding stent and a stent delivery system that can reduce resistance when housed in the sheath and when released from the sheath.

  Further, in order to efficiently maintain the curvature of the housing and efficiently suppress interference with the sheath of the housing, the length of each of the parts of the housing located on both sides via the opening in the circumferential direction is It is preferable to make the length larger than the length of the opening in the circumferential direction, or to arrange the opening in the center of the housing.

  When the self-expanding stent is applied to a thin lumen, it is preferable that three or more housings are arranged at intervals in the circumferential direction of the stent.

  In order to accurately view the position and range of the stent, the housing is preferably arranged at one end and the other end of the stent.

  In order to facilitate storage and release of the stent from the sheath, it is preferable that the outer ends of the housing are aligned so as not to protrude outwardly from one end and the other end of the stent.

  The marker can have, for example, X-ray contrast properties.

It is the schematic for demonstrating the stent delivery system which concerns on embodiment of this invention. It is sectional drawing for demonstrating the front-end | tip part of the stent delivery system shown by FIG. FIG. 3 is a development view for explaining the stent in a contracted state shown in FIG. 2. It is an expanded view for demonstrating the stent of an expansion state. It is explanatory drawing for demonstrating the marker hole shown by FIG. It is the schematic for demonstrating the indwelling method of a stent, and has arrived at the target site | part. It is the schematic for demonstrating the placement method of a stent, and has shown discharge | release of the stent. It is explanatory drawing for demonstrating the modification 1 which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the modification 2 which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the modification 3 which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view for explaining a stent delivery system according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining a distal end portion of the stent delivery system shown in FIG.

  A stent delivery system 100 according to an embodiment of the present invention is used to improve a stenosis (or occlusion) generated in a lumen in a living body, and a sheath 140 in which a stent (self-expanding stent) 120 is housed. And a shaft portion 160 inserted through the sheath 140. The stent 120 is a self-expanding type and is housed in a contracted state on the inner surface of the distal end portion of the sheath 140. As will be described later, resistance when being housed in the sheath 140 and discharged from the sheath 140 is reduced. After reaching the stenosis, it is restored (expanded) to the shape before contraction, thereby being adhered and fixed to the inner surface of the stenosis.

  The lumen in the living body is, for example, a blood vessel, a bile duct, a trachea, an esophagus, or a urethra. The purpose of the improvement of the stenosis is, for example, interventional treatment for prevention of restenosis after percutaneous transluminal coronary angioplasty (PTCA) and peripheral arterial disease (PAD) in peripheral blood vessels of the lower limbs. It is.

  The sheath 140 has a hollow sheath body 142 and a sheath hub 146 fixed to the proximal end of the sheath body 142. The sheath main body 142 has a distal end portion 143 that is a portion for housing the stent 120 and a guide wire port 144. The guide wire port 144 is disposed between the distal end portion 143 and the sheath hub 146 and is used to lead out the guide wire 150 introduced from the distal end portion of the shaft portion 160 to the outside.

  The sheath hub 146 has a side port 148 and holds the shaft portion 160 in a slidable and liquid-tight manner. The side port 148 communicates with a space S formed between the inner periphery of the sheath 140 and the outer periphery of the shaft portion 160, and is configured to be able to supply liquids such as physiological saline, contrast medium, Ringer's solution, for example. ing.

  The outer diameter of the distal end portion 143 of the sheath main body 142 is, for example, 0.5 to 4.0 mm. When applied to a thin lumen such as a peripheral blood vessel of the lower limb, 0.8 to 2.0 mm is preferable. Is, for example, 0.2 to 1.8 mm.

  The constituent material of the sheath body 142 is, for example, a polyolefin such as polyethylene or polypropylene, a fluoropolymer such as nylon, polyethylene terephthalate, PTFE (polytetrafluoroethylene) or ETFE (a copolymer of tetrafluoroethylene and ethylene), or thermoplastic. It is an elastomer. The thermoplastic elastomer is, for example, a polyamide elastomer, a polyurethane elastomer, a polyethylene terephthalate elastomer, a polyethylene elastomer, or a polypropylene elastomer.

  The constituent material of the sheath hub 146 is, for example, a synthetic resin such as polycarbonate, polyolefin, styrene resin, or polyester, stainless steel, aluminum, or an aluminum alloy. The polyolefin is, for example, polyethylene, polypropylene, ethylene-propylene copolymer. Examples of the styrene resin include polystyrene, MS resin (methacrylate-styrene copolymer), and MBS resin (methacrylate-butylene-styrene copolymer).

  The shaft portion 160 includes a shaft main body 162, a distal end side tube 164, and a shaft hub 168.

  The shaft main body 162 is solid, and includes a distal end portion to which the proximal end portion of the distal end side tube 164 is coupled, a proximal end portion to which the shaft hub 168 is fixed, and a cylindrical protrusion that projects outward from the shaft hub 168. Part 163. The shaft body 162 is not limited to being solid, and may be hollow or coiled as necessary.

  The distal side tube 164 is connected to the distal end of the shaft main body 162, has a lumen 165, a stent stopper 166, and a sheath stopper 170, and is configured to protrude from the distal end portion 143 of the sheath main body 142.

  The stent stopper 166 is disposed on the outer surface of the distal end side tube 164, is located on the proximal end side with respect to the stent 120 disposed on the inner surface of the distal end portion 143 of the sheath main body 142, and is configured to be able to contact the stent 120. Therefore, when the sheath body 142 is retracted to the proximal end side with respect to the distal end side tube 164, the proximal end portion of the stent 120 comes into contact with the stent stopper 166 and is restrained.

  As a result, the stent 120 is released from the sheath body distal end portion 143 (is pushed out by the stent stopper 166) because the stent 120 does not move along with the retreat of the sheath body 142. When the stent 120 is released from the sheath main body 142, the stress for maintaining the contracted state applied by the inner surface of the sheath main body distal end portion 143 disappears, so that the stent 120 is restored to the shape before contraction and expanded. .

  In addition, the means for releasing the stent 120 in which the contracted state is maintained is not limited to the above mechanism.

  The sheath stopper 170 is disposed on the outer surface of the distal end side tube 164 protruding from the distal end portion 143 of the sheath main body 142. This prevents the sheath body 142 from moving beyond the sheath stopper 170 toward the distal end.

  The constituent materials of the distal end side tube 164 and the shaft body 162 are, for example, stainless steel, superelastic metal, polyolefin such as polyethylene and polypropylene, fluorine-based polymer such as nylon, polyethylene terephthalate, and ETFE, PEEK (polyether ether ketone), polyimide It is.

  The constituent material of the shaft hub 168 is, for example, polycarbonate, polyolefin, styrene resin, synthetic resin such as polyester, stainless steel, aluminum, or aluminum alloy.

  Next, the stent 120 will be described in detail.

  3 is a developed view for explaining the stent in the contracted state shown in FIG. 2, FIG. 4 is a developed view for explaining the stent in the expanded state, and FIG. 5 is a diagram explaining the marker hole shown in FIG. It is explanatory drawing for doing.

  The stent 120 is in the contracted state shown in FIG. 3 when housed in the sheath body 142, but is shown in FIG. 4 before being housed in the sheath body 142 and after being released from the sheath body 142. In the expanded (restored) state.

  As clearly shown in FIG. 4, the stent 120 includes a plurality of wavy struts 122 arranged at intervals in the axial direction A of the stent 120, connection struts 126 for connecting adjacent wavy struts 122, and And a housing 130 in which a marker 134 having X-ray contrast is accommodated. The marker 134 is disposed in order to improve the visibility during use (treatment).

  The wavy strut 122 has a straight portion 123 and a top portion 124 that is a folded portion of the straight portion 123, and extends (circulates) in the circumferential direction C of the stent 120. The wavy struts 122 are directly connected to the adjacent wavy struts 122 at an appropriate interval (intermittently) in the middle of the linear portion 123 or at the top portion 124, or are connected via the connecting struts 126 as a unit. A cylindrical structure is formed, and is configured to be able to expand and contract in the radial direction.

  Therefore, when the contracted stent 120 (FIG. 3) expands (restores), a cell (closed space) including the deformed linear portion 123, the top portion 124, and the connecting strut 126 is formed between the adjacent wavy struts 122. 128 will be formed (FIG. 4). Note that the configuration of the wavy strut 122 that allows the stent 120 to expand and contract in the radial direction is not limited to the above-described embodiment.

  The outer diameter of the stent 120 in the contracted (reduced diameter) state corresponds to the inner diameter of the distal end portion 143 of the sheath body 142. The outer diameter of the expanded (restored) state of the stent 120 is, for example, 2.0 to 5.0 mm. The thickness of the stent is, for example, 0.05 to 0.15 mm.

  The stent 120 is self-expanding and requires a restoring force to its original shape, so a superelastic alloy such as a titanium-nickel alloy is preferable, but a polymer material or other metal material is applied as necessary. Is possible. Examples of the polymer material include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, and fluorine-containing polymers such as polytetrafluoroethylene and a tetrafluoroethylene-ethylene copolymer. The metal material is, for example, a cobalt-chromium alloy, stainless steel, iron, titanium, aluminum, tin, or a zinc-tungsten alloy.

  The formation method of the wavy struts 122 and the connection struts 126 is not particularly limited. For example, the outer circumference of the cylindrical stent material is laser-cut based on the strut pattern (the pattern of the wavy struts 122 and the connection struts 126). Alternatively, it can be formed by arranging a masking material corresponding to the strut pattern and performing etching.

  The housing 130 has a marker hole (opening) 132 in which the marker 134 is accommodated and fixed, and is disposed on the top 124 of the wavy strut 122. The wavy struts 122 in which the housing 130 is disposed are positioned at one end 120A and the other end 120B in the axial direction A of the stent 120, and the position and range of the stent 120 can be accurately visually confirmed.

Marker hole 132, as shown in FIG. 5, the width in the circumferential direction C perpendicular to the axial direction A of the stent 120 (length) _{W C} is the width (length) of the housing 130 in the circumferential direction C of the _{W T} 1/3 or less. Accordingly, when the stent 120 is housed in the sheath body distal end portion 143 and released from the sheath body distal end portion 143, interference with the sheath body distal end portion 143 of the housing 130, that is, the housing 30 is placed on the inner surface of the sheath body distal end portion 143. It is suppressed that it is caught. That is, even if the marker hole 132 exists, it can be stored in the sheath body distal end 143 and discharged from the sheath body distal end 143 while maintaining the curvature of the housing 130. Is reduced.

Marker hole 132 is a rectangular shape, the length _{L A} in the axial direction A, for greater than a width _{W C,} to ensure the area of the marker hole 132 (the size of the marker 134), to maintain the radiopaque marker 134 It is possible.

With respect to the circumferential direction C, the widths (lengths) W _L and W _R of the portions located on both sides of the marker hole 132 are larger than the length W _{C of} the marker hole 132, and the marker hole 132 is formed in the housing 130. Located in the center of Therefore, it is possible to efficiently maintain the curvature of the housing and efficiently suppress interference with the sheath body distal end portion 134 of the housing.

  The outer end of the housing 130 coincides with the outer end of the top portion 124 where the housing 130 is not disposed in the axial direction A, and does not protrude outward from the one end 120A and the other end 120B of the stent 120. Therefore, the stent can be easily stored in the sheath and released from the sheath.

  When the stent 120 is applied to a thin lumen, it is preferable to arrange three or more housings 130 (three in FIGS. 3 and 4) at intervals in the circumferential direction C.

  The housing 130 is not limited to being disposed at the one end 120A and the other end 120B of the stent 120. Further, the installation site of the housing 130 is not limited to the top portion 124 of the wavy strut 122.

  The constituent material of the marker 134 is, for example, one (single) or two or more selected from the group of elements consisting of gold, platinum, tantalum, iridium, rhenium, tungsten, palladium, rhodium, silver, ruthenium, and hafnium. (Alloy).

  The marker 134 is not limited to a form having an X-ray contrast property, and a marker having an ultrasonic contrast property can be applied as necessary.

  The method for fixing the marker 134 to the housing 130 is not particularly limited, and for example, caulking, welding, or adhesion can be applied.

  Next, a stent placement method will be described.

  FIG. 6 is a schematic diagram for explaining the arrival of the distal end portion of the stent delivery system at a target site, and FIG. 7 is a schematic diagram for explaining the release of the stent.

  First, the distal end portion of the stent delivery system 100 in which the guide wire is inserted into the distal end side tube 164 is inserted into the patient's lumen 180, and the target wire (indwelling position) is placed with the guide wire 150 protruding from the distal end portion in advance. The stenosis part 182 which is a part) is positioned (FIG. 6). At this time, the position of the marker 134 of the housing 130 disposed at the one end 120A and the other end 120B of the stent 120 is visually confirmed (confirmed) by X-ray irradiation, so that positioning can be performed accurately, quickly and easily. It is. The stent 120 is in a contracted state due to stress applied by the inner surface of the sheath body distal end portion 143, and is in close contact with the inner surface of the sheath body distal end portion 143.

  Then, the sheath 140 is pulled, and the sheath main body 142 is moved backward with respect to the shaft portion 160 toward the proximal end side. Since the stent stopper 166 protrudes from the outer surface of the distal end side tube 164 of the shaft portion 160, the other end (proximal end portion) 120B of the stent 120 comes into contact with the stent stopper 166 and is restrained.

  Accordingly, since the stent 120 is not accompanied by the retraction of the sheath body 142, the inner surface of the distal end portion 143 of the sheath body retreats to the proximal end side while sliding on the outer periphery of the stent 120, and the stent 120 finally becomes the sheath It is discharged from the main body tip 143 (is pushed out by the stent stopper 166).

  When the stent 120 is released from the sheath main body 142, the stress for maintaining the contracted state applied by the inner surface of the sheath main body distal end portion 143 disappears, so that the stent 120 is restored to the shape before contraction and expanded (FIG. 7). ).

  The expanded stent 120 maintains the lumen shape by being fixed (indwelled) in close contact with the inner wall of the narrowed portion 182. The stent delivery system 100 from which the stent 120 has been separated is retracted and removed from the lumen 180.

  8-10 is a top view for demonstrating the modifications 1-3 which concern on embodiment of this invention.

  The shape of the marker hole 132 is not limited to a rectangle, and for example, a rounded rectangle (FIG. 8), an ellipse (FIG. 9), and a rhombus (FIG. 10) can be applied as appropriate.

  As described above, in the present embodiment, it is possible to provide a self-expanding stent that can reduce resistance when housed in and released from the sheath.

  In addition, it is also possible to improve lubricity by disposing (coating or fixing) a hydrophilic polymer on the outer surface of the sheath 140. Examples of hydrophilic polymers include poly (2-hydroxyethyl methacrylate), polyhydroxyethyl acrylate, hydroxypropyl cellulose, methyl vinyl ether maleic anhydride copolymer, polyethylene glycol, polyacrylamide, polyvinyl pyrrolidone, dimethylacrylamide-glycidyl methacrylate copolymer It is a coalescence.

  In order to improve the slidability between the stent 120 and the shaft portion 160 on the inner surface of the sheath main body 142, the above-described hydrophilic polymer can be disposed.

  It is also possible to coat the outer surface of the distal end side tube 164 of the shaft portion 160 with a material having biocompatibility, particularly antithrombotic properties. The antithrombogenic material is, for example, polyhydroxyethyl methacrylate, a copolymer of hydroxyethyl methacrylate and styrene (for example, a HEMA-St-HEMA block copolymer).

  In the distal end side tube 164 of the shaft portion 160, it is possible to improve the lubricity by disposing the above-described hydrophilic polymer on the outer surface of a portion that may protrude from the distal end of the sheath body 142.

  If necessary, the above-mentioned hydrophilic polymer can be disposed on the entire outer surface of the distal tube 164 or disposed on the inner surface of the distal tube 164 in order to improve the slidability with the guide wire 150. is there.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the stent delivery system is not limited to a rapid exchange (RX) type, but can be applied to an over-the-wire (OTW) type.

  It is also possible to coat the stent surface with a drug (a physiologically active substance). The drug is, for example, an anticancer agent, an immunosuppressive agent, an antibiotic, an immunosuppressive agent, or an antithrombotic agent.

100 stent delivery system,
120 stent (self-expanding stent),
120A one end,
120B The other end (base end side end),
122 wavy struts,
123 linear part,
124 top,
126 connecting struts,
128 cells,
130 housing,
132 Marker hole (opening),
134 markers,
140 sheath,
142 sheath body,
143 tip,
144 Guide wire port,
146 sheath hub,
148 side port,
150 guide wire,
160 shaft part,
162 shaft body,
163 cylindrical protrusion,
164 distal tube,
165 lumens,
166 stent stopper,
168 shaft hub,
170 sheath stopper,
180 lumens,
182 Stenosis,
A axis direction,
C circumferential direction,
L _A length,
S space,
W _C width (length),
W _L , W _R width (length),
W _T housing width (length).

Claims (8)

A self-expandable stent that is housed in a sheath in a contracted state, reaches a target site, and is then released from the sheath to restore the shape before contraction,
Wavy struts,
Has an opening markers with contrast property is housed, and have a housing that is placed on top of the corrugated struts,
The length of the opening in the circumferential direction perpendicular to the axial direction of the stent is
A self-expanding stent that is smaller than the length of the opening in the axial direction and not more than one-third of the length of the housing in the circumferential direction.   2. The self-expanding type according to claim 1, wherein the length of each part of the housing located on both sides through the opening in the circumferential direction is larger than the length of the opening in the circumferential direction. Stent.   The self-expanding stent according to claim 2, wherein the opening is located at a central portion of the housing.   The self-expanding stent according to any one of claims 1 to 3, wherein three or more housings are arranged at intervals in the circumferential direction of the stent.   The self-expanding stent according to any one of claims 1 to 4, wherein the housing is disposed at one end and the other end of the stent.   The self-expanding stent according to claim 5, wherein the outer end of the housing is aligned so as not to protrude outwardly from one end and the other end of the stent.   The self-expanding stent according to any one of claims 1 to 6, wherein the marker has X-ray contrast properties. Sheath,
The self-expanding device according to any one of claims 1 to 7, wherein the self-expanding device is stored in the sheath in a contracted state, reaches a target site, and is then released from the sheath to restore the shape before the contraction. Type stent,
A stent delivery system comprising:

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