Patent Description:
Typically, treatment has been performed, in which, e.g., a cardiovascular, cerebral-vascular, or peripheral-vascular lumen narrowed or occluded with, e.g., plaque and became ischemic accordingly is expanded in order to ensure the patency of a lesion area. For example, a catheter treatment has been known, in which a stent or a balloon sheathed in a catheter is deployed in a lesion area. As one example of the stent used for such catheter treatment, a stent provided with a plurality of struts which extends radially from a center axis has been proposed (see Patent Document <NUM>).

<CIT> discloses a stent with a first stent structure configured to have a plurality of cells by means of the wire crossing pattern of a woven structure and be provided in a hollow cylindrical shape by weaving a metal wire made of a shape-memory alloy in a specific pattern on a jig; and a second stent structure formed as a 3D print that is provided to have a plurality of cells by means of the wire crossing pattern of a printed structure and also have a hollow cylindrical shape by performing 3D printing using a printing material including a biodegradable polymer and a drug, and disposed such that it covers the outer circumferential surface of the first stent structure or the outer circumferential surface thereof is covered with the first stent structure.

In the case of using an indwelling stent for expanding a vascular lumen, there is a probability that restenosis or reocclusion occurs in a blood vessel after implantation of the stent or a complication such as a thrombosis occurs. On the other hand, in the case of using a balloon for expanding a vascular lumen, a blood vessel is temporarily closed, and for this reason, there is a probability that infarction particularly in a distal side blood vessel occurs. Further, there is a concern regarding, e.g., limitation on an expansion time and a remaining narrowed lesion area and restenosis after treatment. In addition, since the blood vessel expanded by the balloon is in a linear shape, there is a probability that a hemorrhagic complication due to, e.g., blood vessel damage or rupture or infarction of a penetrating branch of a peripheral blood vessel occurs.

In the case of a recovery stent such as the stent of Patent Document <NUM>, the stent is recovered after having been temporarily implanted in a blood vessel, so that the various complication risks as described above can be reduced while the patency of the blood vessel is ensured. However, if the surface area of the stent is increased in order to more uniformly expand the narrowed blood vessel, the bending stiffness of the stent becomes too high, leading to poor shape followability to a vascular structure. If the surface area (the area excluding the area of the cell holes) of the stent is increased, the volume of the stent increases, and for this reason, it is difficult to sheathe the narrowed stent in a thin catheter. Since the stent of Patent Document <NUM> includes the plurality of struts, it is assumed that shape followability and diameter reducibility are significantly degraded if the surface area is merely increased.

An object of the present invention is to provide a stent having a large surface area and having excellent shape followability to a vascular structure and excellent diameter reducibility.

The present invention relates to a stent that is inserted into a catheter and pushed out of the catheter in a blood vessel to expand the blood vessel. The stent includes a first stent body configured such that a plurality of first cells including struts arranged in a frame shape spreads in a circumferential direction and is continuously arranged in a center axis direction, and a second stent body configured such that a plurality of second cells including struts arranged in a frame shape spreads in a circumferential direction and is continuously arranged in a center axis direction and inserted into the first stent body. In a state in which the second stent body is inserted into the first stent body, an intersection between the second cells is arranged in a hole of each first cell. The first stent body and the second stent body are not coupled to each other in a radial direction.

In the state in which the second stent body is inserted into the first stent body, the second stent body may press the first stent body outward in the radial direction.

In a configuration in which the intersection between the second cells is arranged in the hole of each first cell, one intersection between the second cells may be arranged in one hole of each first cell.

In the state in which the second stent body is inserted into the first stent body, the percentage of a non-hole portion per unit surface area in a portion where the first stent body and the second stent body overlap with each other may be <NUM> to <NUM>%.

Each first cell may include, in an annular direction inclined with respect to the circumferential direction, a pair of first struts and one first strut arranged with a clearance from the pair of first struts, and each second cell may include, in an annular direction inclined with respect to the circumferential direction, a pair of second struts and one second strut arranged with a clearance from the pair of second struts.

Adjacent ones of the plurality of first cells may be connected to each other at a substantially S-shaped first intersection in the annular direction inclined with respect to the circumferential direction, and adjacent ones of the plurality of second cells may be connected to each other at a substantially S-shaped second intersection in the annular direction inclined with respect to the circumferential direction.

The annular direction in which the plurality of first cells is connected at the first intersections and the annular direction in which the plurality of second cells is connected at the second intersections may be symmetrical with respect to a line along the radial direction.

A proximal side end portion of the first stent body and a proximal side end portion of the second stent body may be connected at different positions in the axial direction of a push wire.

The stent may further include a coating film between the first stent body and the second stent body.

A strand having a high radiopacity may be wound around at least one of the first stent body or the second stent body in a spiral shape.

According to the present invention, a stent can be provided, which has a large surface area and having excellent shape followability to a vascular structure and excellent diameter reducibility.

Hereinafter, embodiments of a stent according to the present invention will be described. Note that any of the drawings attached to the present specification shows a schematic view and the shape, scale, longitudinal-lateral dimensional ratio, etc. of each portion are changed or exaggerated as compared to actual shape, scale, longitudinal-lateral dimensional ratio, etc. for the sake of easy understanding of the drawings. Moreover, in the drawings, hatching showing the cross-section of members has been omitted where appropriate. In the present specification etc., terms specifying shapes, geometric conditions, and the degrees thereof, such as "parallel" and "direction", include not only exact meanings of these terms, but also ranges taken as being substantially parallel and being substantially in a direction. In description in the present specification etc., in an axial direction (a center axis direction) LD, a proximal side close to a practitioner will be referred to as a side LD1, and a distal side distant from the practitioner will be referred to as a side LD2. A direction perpendicular to the axial direction LD will be referred to as a radial direction RD. Moreover, in description in the present specification etc., a direction in which cells spread will be referred to as a circumferential direction (a circumferential direction OD). The circumferential direction includes not only the radial direction RD, but also a direction inclined with respect to the radial direction RD.

<FIG> is a schematic side view of a stent <NUM> of a first embodiment. <FIG> is a schematic perspective view of the stent <NUM> shown in <FIG>. <FIG> is a development view showing a state in which part of a first stent body <NUM> of the first embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which part of a second stent body <NUM> of the first embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which part of the stent <NUM> of the first embodiment is virtually opened in a planar shape. <FIG> is a view for describing the outer diameter D1 of the simple first stent body <NUM>. <FIG> is a view for describing the outer diameter D2 of the simple second stent body <NUM>. <FIG> is a view for describing steps of inserting the second stent body <NUM> into the first stent body <NUM>. <FIG> is a sectional view along an s1-s1 line of <FIG>.

For the sake of easy distinguishing of the first stent body <NUM> and the second stent body <NUM> in the drawings showing the first embodiment and other embodiments, a strut of the first stent body <NUM> is indicated by black, and a strut of the second stent body <NUM> is indicated by white. Moreover, in the present specification etc., the "cell" indicates a portion surrounded by a wire-like material forming a mesh pattern. The "cell" includes not only a form in which a shape and a size are the same over the stent body, but also a form in which a shape and a size are different. The "strut" indicates an elongated band-shaped portion made of the wire-like material. In the present specification etc., a cell opening will also be referred to as a "hole", and a portion where struts of adjacent cells are connected to or overlap with each other will also be referred to as an "intersection". Of the intersection, a point at which struts cross each other will also be referred to as an "intersecting point". The intersection may have a certain region (area). The intersection may include a plurality of intersecting points.

The stent <NUM> of the first embodiment is used, for example, as follows: the stent <NUM> is sheathed (housed) in (inserted into) a catheter (not shown) and is pushed out of the catheter and is deployed in a vascular lumen, and in this manner, expands a narrowed or occluded blood vessel. As shown in <FIG> and <FIG>, the stent <NUM> is substantially in a cylindrical shape in a diameter-expanded state. Although not shown in the figure, the stent <NUM> is in an elongated cylindrical shape in a diameter-narrowed state. A push wire <NUM> is connected to a proximal side LD1 end portion of the stent <NUM>, and a distal side LD2 end portion of the stent <NUM> is connected to a distal end shaft <NUM>. Examples of a method for connecting the proximal side end portion of the stent <NUM> and the push wire <NUM> to each other may include welding, UV bonding, and silver solder infiltration, but is not particularly limited as long as the connection method is used for general medical equipment. Note that the form of connection between the proximal side end portion of the stent <NUM> and the push wire <NUM> will be described later.

The push wire <NUM> is a member to be operated by the practitioner to move the stent <NUM>. The practitioner pushes or pulls the push wire <NUM> via an operator (not shown) coupled to the proximal side LD1 of the push wire <NUM>, thereby moving the stent <NUM> back and forth in the catheter or the blood vessel. The practitioner moves the push wire <NUM> back and forth, thereby temporarily implanting the stent <NUM> in a lesion area or recovering the stent <NUM> from a lesion area. The distal end shaft <NUM> is a member serving as a mark for checking the distal side LD2 position of the stent <NUM> on an X-ray transparent image, and for example, the entirety or part of the distal end shaft <NUM> is made of a material having a high radiopacity. The material having the high radiopacity indicates a material through which no radiation such as an X-ray penetrates or which has a low radiant transmittance. Note that the distal end shaft <NUM> may be made, for example, of the same material as that of the push wire <NUM>.

The stent <NUM> includes the first stent body <NUM> and the second stent body <NUM>. The first stent body <NUM> is a substantially cylindrical structure arranged outside the stent <NUM>. The second stent body <NUM> is a substantially cylindrical structure arranged inside the first stent body <NUM>. The stent <NUM> is a stent having such a double-layer structure in which the second stent body <NUM> is inserted into the first stent body <NUM>. In a state in which the second stent body <NUM> is inserted into the first stent body <NUM>, the first stent body <NUM> and the second stent body <NUM> are not coupled to each other in the radial direction. Specifically, the first stent body <NUM> and the second stent body <NUM> are coupled to each other via the push wire <NUM> or the distal end shaft <NUM>, but are not coupled to each other between the push wire <NUM> and the distal end shaft <NUM>. Thus, the stent <NUM> is configured such that the first stent body <NUM> and the second stent body <NUM> are independently deformable on the same layer.

As described later, the stent <NUM> of the first embodiment is produced in such a manner that the second stent body <NUM> having a greater outer diameter than that of the first stent body <NUM> is inserted, in a diameter-narrowed state, into the first stent body <NUM>. Thus, in the stent <NUM>, the inserted second stent body <NUM> constantly presses the first stent body <NUM> outward in the radial direction RD. With this configuration, the stent <NUM> is configured so that the first stent body <NUM> and the second stent body <NUM> can be more closely in contact with each other while the state in which the first stent body <NUM> and the second stent body <NUM> are independently deformable on the same layer is maintained.

As shown in <FIG>, on the proximal side LD1 of the stent <NUM>, end portions of the first stent body <NUM> and the second stent body <NUM> are gradually narrowed toward the push wire <NUM>, and are connected to the push wire <NUM>. Similarly, on the distal side LD2 of the stent <NUM>, end portions of the first stent body <NUM> and the second stent body <NUM> are gradually narrowed toward the distal end shaft <NUM>, and are connected to the distal end shaft <NUM>.

As shown in <FIG>, the first stent body <NUM> is configured such that a plurality of outer cells (first cells) <NUM> including struts <NUM> arranged in a frame shape spreads in the radial direction (circumferential direction) RD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> including the struts <NUM> arranged in the frame shape spreads in the radial direction RD and is continuous in the axial direction LD. A hole <NUM> is formed in the outer cell <NUM>. Adjacent ones of the outer cells <NUM> are connected to each other at an intersecting point <NUM>.

As shown in <FIG>, the second stent body <NUM> is configured such that a plurality of inner cells (second cells) <NUM> including struts <NUM> arranged in a frame shape spreads in the radial direction (circumferential direction) RD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> including the struts <NUM> arranged in the frame shape spreads in the radial direction RD and is continuous in the axial direction LD. A hole <NUM> is formed in the inner cell <NUM>. Adjacent ones of the inner cells <NUM> are connected to each other at an intersecting point <NUM>.

As shown in <FIG>, in the stent <NUM> of the first embodiment, the outer cell <NUM> forming the first stent body <NUM> and the inner cell <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the first embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the intersecting point <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the intersecting point <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one intersecting point <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. The mesh patterns of the stent bodies overlap with each other as described above, and therefore, the density of the mesh pattern is increased over the entire stent. Thus, the surface area of the stent <NUM> can be increased. In the stent <NUM> of the first embodiment, the percentage of a non-hole portion per unit surface area in the portion where the first stent body <NUM> and the second stent body <NUM> overlap with each other is <NUM> to <NUM>%.

As shown in <FIG>, in the first embodiment, a relationship between the outer diameter D1 of the simple first stent body <NUM> and the outer diameter D2 of the simple second stent body <NUM> is set to D1 < D2. Thus, according to the steps indicated by arrows in <FIG>, the second stent body <NUM> having a greater outer diameter than that of the first stent body <NUM> is narrowed into the form of a second stent body 20A, and the second stent body 20A is inserted into the first stent body <NUM>. In this manner, due to expansive force of the second stent body <NUM> itself, the stent <NUM> can be produced with such a double-layer structure in which the second stent body <NUM> closely contacts the first stent body <NUM> from the inside thereof. Note that for the sake of easy understanding, <FIG> shows only an annular circumferential cell line of each stent body.

In the stent <NUM> produced as described above, the first stent body <NUM> and the second stent body <NUM> closely contact each other with no clearance therebetween in the radial direction RD due to the above-described expansive force of the second stent body <NUM> itself, as shown in <FIG>. Thus, in the axial direction LD (see <FIG>) of the stent <NUM>, it is less likely that the positions of the first stent body <NUM> and the second stent body <NUM> are relatively misaligned from each other.

In the first embodiment, the second stent body <NUM> itself inserted in the narrowed state into the first stent body <NUM> serves as a self-expanding body (elastic body). Thus, the second stent body <NUM> constantly presses the first stent body <NUM> outward in the radial direction RD. Consequently, even if the first stent body <NUM> and the second stent body <NUM> are not coupled to each other in the radial direction, the first stent body <NUM> and the second stent body <NUM> can more closely contact each other. Moreover, since the first stent body <NUM> and the second stent body <NUM> are not coupled to each other in the radial direction in the stent <NUM>, the state in which the first stent body <NUM> and the second stent body <NUM> are independently deformable on the same layer can be maintained. Further, the stent <NUM> having the double-layer structure has the total expansive force of the expansive force of the first stent body <NUM> outside and the expansive force of the second stent body <NUM> inside. Thus, even if the stent <NUM> has the same surface area as that of a stent having a single-layer structure, the stent <NUM> can have a greater expansive force.

As a material forming the stent <NUM> (the first stent body <NUM>, the second stent body <NUM>), a material itself having a high stiffness and a high biological compatibility is preferred. Examples of such a material include titanium, nickel, stainless steel, platinum, gold, silver, copper, iron, chromium, cobalt, aluminum, molybdenum, manganese, tantalum, tungsten, niobium, magnesium, calcium, and alloy containing these materials. Particularly, the stent <NUM> is preferably made of a material having superelastic properties, such as nickel titanium (Ni-Ti) alloy. The mesh patterns of the first stent body <NUM> and the second stent body <NUM> may be produced, for example, in such a manner that substantially cylindrical tubes made of the above-described material are machined with laser.

As the material of the stent <NUM>, synthetic resin materials such as polyolefin including PE and PP, polyamide, polyvinyl chloride, polyphenylene sulfide, polycarbonate, polyether, and polymethylmethacrylate may also be used. Further, biodegradable resins (biodegradable polymers) such as polylactate (PLA), polyhydroxybutyrate (PHB), polyglycolic acid (PGA), and poly(ε-caprolactone) may also be used. Of these materials, titanium, nickel, stainless steel, platinum, gold, silver, copper, magnesium, or alloy containing these materials are preferred. Examples of such alloy include Ni-Ti alloy, Cu-Mn alloy, Cu-Cd alloy, Co-Cr alloy, Cu-Al-Mn alloy, Au-Cd-Ag alloy, Ti-Al-V alloy, and alloy of magnesium and Zr, Y, Ti, Ta, Nd, Nb, Zn, Ca, Al, Li, Mn, etc. In addition to the materials described above, non-biodegradable resins may be used as the material of the stent <NUM>. As described above, any material may be used to form the stent <NUM> as long as such a material has a biological compatibility.

The stent <NUM> may contain a medical agent. The stent <NUM> containing the medical agent as described herein indicates that the stent <NUM> releasably carries the medical agent so as to dissolve out the medical agent. Although the medical agent is not limited, a physiologically active substance may be used, for example. Examples of the physiologically active substance include a medical agent for inhibiting intima thickening, a carcinostatic, an immunosuppressant, an antibiotic, an antirheumatic, an antithrombotic, an HMG-CoA reductase inhibitor, an ACE inhibitor, a calcium channel blocker, an antilipemic, an anti-inflammatory, an integrin inhibitor, an antiallergic, an antioxidant, a GPIIbIIIa antagonist, retinoid, flavonoid, carotenoid, a lipid improver, a DNA synthesis inhibitor, a tyrosine kinase inhibitor, an antiplatelet, a vascular smooth muscle growth inhibitor, an anti-inflammatory agent, and interferon, and these medical agents may be used in combination.

For example, in a case where the first stent body <NUM> and the second stent body <NUM> are formed using superelastic alloy tubes, tubes having diameters of about <NUM> to <NUM> are machined with laser, and in this manner, mesh patterns are formed. Thereafter, the mesh patterns are stretched in the radial direction, and in this manner, can be expanded to desired diameters. As described above, the second stent body <NUM> is inserted into the first stent body <NUM>, and in this manner, the stent <NUM> having the double-layer structure can be produced. The stent <NUM> having the double-layer structure is narrowed in the radial direction from the state shown in <FIG>, and is sheathed in the catheter (not shown). When the stent <NUM> sheathed in the catheter is pushed out, the shape shown in <FIG> is recovered. The stent <NUM> is made of, e.g., an elastic material such as superelastic alloy or shape-memory alloy so that the above-described shape recovery function can be obtained. Note that production of the stent <NUM> is not limited to laser machining, and for example, the stent <NUM> may be produced by other methods such as cutting.

According to the stent <NUM> of the above-described first embodiment, the following advantageous effects are obtained, for example. The stent <NUM> of the first embodiment has the double-layer structure of the first stent body <NUM> and the second stent body <NUM>, and the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the intersecting point <NUM> between the inner cells <NUM> of the second stent body <NUM> is arranged in the hole <NUM> of the outer cell <NUM> of the first stent body <NUM> (see <FIG>). The mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern can be increased over the entire stent. Thus, the surface area of the stent <NUM> can be increased. Consequently, according to the stent <NUM> of the first embodiment, the narrowed blood vessel can be more uniformly expanded.

The stent <NUM> of the first embodiment is configured such that in the state in which the second stent body <NUM> is inserted into the first stent body <NUM>, the first stent body <NUM> and the second stent body <NUM> are not coupled to each other in the radial direction. According to the present configuration, the first stent body <NUM> and the second stent body <NUM> are independently deformable on the same layer, and a contact state interfering with deformation of these bodies is less likely to occur. Thus, the flexibility of the entire stent can be more enhanced. As described above, even if the stent <NUM> of the first embodiment has a great surface area, an excessive increase in bending stiffness can be prevented, and therefore, excellent shape followability (followability of shape) to a vascular structure can be exhibited.

Moreover, as described above, in the stent <NUM> of the first embodiment, the first stent body <NUM> and the second stent body <NUM> are independently deformable on the same layer, and therefore, the stent <NUM> can be narrowed without interference among the struts of each layer. Since the stent <NUM> of the first embodiment has excellent diameter reducibility (reducibility of diameter), the stent <NUM> can be easily sheathed even in a thin catheter as compared to a stent having a mesh pattern with a single-layer structure and a great surface area.

Thus, the stent <NUM> of the first embodiment has a great surface area, and has excellent shape followability to a vascular structure and excellent diameter reducibility. Note that in a case where a wire-like material is braided to form a double-layer structure, the wire-like material also extends among layers, and for this reason, the braided layers are not independently deformable on the same layer. For this reason, even if the surface area of the stent is increased by the braided double-layer structure, it is difficult to obtain shape followability and diameter reducibility as in the stent <NUM> of the first embodiment.

An effect in a case where the stent <NUM> of the first embodiment is temporarily implanted in a bent blood vessel will be described herein. <FIG> is a view for describing an internal state in a case where the stent <NUM> is bent. <FIG> schematically shows the internal state in a case where the stent <NUM> is temporarily implanted in the bent blood vessel. In <FIG>, arrows A1 inside the stent <NUM> indicate the direction of action of the self-expanding force (pressure) of the second stent body <NUM>. As shown in <FIG>, in the stent <NUM>, the second stent body <NUM> constantly presses, due to the self-expanding force thereof, the first stent body <NUM> outward. Thus, in a blood vessel having a small bending radius, a phenomenon socalled "kink" is less likely to occur in the stent <NUM>. The kink indicates that the section of the stent is deformed substantially to an oval shape. Moreover, in the bent blood vessel, a force of buckling the stent <NUM> is applied as indicated by arrows A2 in <FIG>. This force is considerable particularly inside the bent portion, and the self-expanding force of the second stent body <NUM> indicated by the arrows A1 acts so as to face the force indicated by the arrows A2. Thus, even if the bending radius of the stent <NUM> decreases in the bent blood vessel, the stent <NUM> is less likely to be bent or kink.

The stent <NUM> of the above-described first embodiment is sheathed in the catheter, and is deployed in a lesion area in a vascular lumen. In this manner, the vascular lumen can be expanded, and the patency of the lesion area can be ensured. The stent <NUM> is recovered, without implanted for a long period of time, after a lapse of a predetermined period so that occurrence of restenosis or reocclusion in the blood vessel after implantation of the stent or occurrence of a defect leading to a complication such as a thrombosis can be reduced. Moreover, the stent <NUM> of the first embodiment has excellent shape followability, and therefore, the blood vessel is less likely to be in a linear shape as compared to a case where a vascular lumen is expanded by a balloon. Thus, the stent <NUM> of the first embodiment is less likely to cause a hemorrhagic complication due to, e.g., blood vessel damage or rupture or infarction of a penetrating branch of a peripheral blood vessel. Note that the stent <NUM> of the first embodiment is not limited to use against coarctation in a vascular lumen, and for example, may also be used against coarctation in an organ of the gastrointestinal system, such as the esophagus or the large intestine. That is, the stent <NUM> of the first embodiment can be used generally for body tissues with lumen structures.

The stent <NUM> of the first embodiment can also be used for treatment of a cerebrovascular spasm that a cerebral blood vessel is narrowed due to a spasm. As one of a treatment method for the cerebrovascular spasm, a blood vessel is expanded by a balloon. However, in the treatment using the balloon, there is a probability that, e.g., vascular occlusion or blood vessel damage occurs. On the other hand, since the stent <NUM> of the first embodiment has excellent shape followability as described above, a blood vessel is less likely to be in a linear shape as compared to a case where a vascular lumen is expanded by a balloon. Thus, it is assumed that the stent <NUM> of the first embodiment is less likely to cause a hemorrhagic complication due to, e.g., blood vessel damage or rupture or infarction of a penetrating branch of a peripheral blood vessel even in a case where the stent <NUM> is used for treatment of the cerebrovascular spasm. Note that stents of other embodiments to be described later also produce advantageous effects similar to those of the stent <NUM> of the first embodiment.

Next, a stent 1A of a second embodiment will be described. The stent 1A of the second embodiment is different from that of the first embodiment in the cell shapes of first and second stent bodies. Other configurations of the stent 1A of the second embodiment are the same as those of the first embodiment. Thus, in the second embodiment, the entirety of the stent 1A is not shown in the figure. Moreover, in description below and the drawings, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the first embodiment, and overlapping description thereof will be omitted as necessary.

<FIG> is a development view showing a state in which a first stent body <NUM> of the second embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the second embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1A of the second embodiment is virtually opened in a planar shape. In the second embodiment, a circumferential direction OD is inclined with respect to a radial direction RD.

The first stent body <NUM> of the second embodiment is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> spreads in the circumferential direction OD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the circumferential direction OD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the circumferential direction OD and is continuously arranged in the axial direction LD.

The outer cell <NUM> includes two struts <NUM> arranged on long sides and two struts <NUM> arranged on short sides. The outer cell <NUM> is configured, when opened in a planar shape, such that the long-side struts <NUM> and the short-side struts <NUM> are diagonally coupled substantially in the form of a parallelogram. The outer cell <NUM> has a hole <NUM>. Adjacent ones of the outer cells <NUM> are connected to each other at an intersecting point <NUM>.

The second stent body <NUM> of the second embodiment is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> spreads in the circumferential direction OD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the circumferential direction OD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the circumferential direction OD and is continuously arranged in the axial direction LD.

The inner cell <NUM> includes two struts <NUM> arranged on long sides and two struts <NUM> arranged on short sides. The inner cell <NUM> is configured, when opened in a planar shape, such that the long-side struts <NUM> and the short-side struts <NUM> are diagonally coupled substantially in the form of a parallelogram. The inner cell <NUM> has a hole <NUM>. Adjacent ones of the inner cells <NUM> are connected to each other at an intersecting point <NUM>.

In the stent 1A of the second embodiment, the plurality of outer cells <NUM> forming the first stent body <NUM> and the plurality of inner cells <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the second embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent 1A of the second embodiment, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the intersecting point <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the intersecting point <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one intersecting point <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. In a case where each stent body is configured, as in the second embodiment, with the cell shape shown in <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1A can be more increased.

Next, a stent 1B of a third embodiment will be described. The stent 1B of the third embodiment is different from that of the first embodiment in the cell shapes of first and second stent bodies. Other configurations of the stent 1B of the third embodiment are the same as those of the first embodiment. Thus, in the third embodiment, the entirety of the stent 1B is not shown in the figure. Moreover, in description below and the drawings, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the first embodiment, and overlapping description thereof will be omitted as necessary.

<FIG> is a development view showing a state in which a first stent body <NUM> of the third embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the third embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1B of the third embodiment is virtually opened in a planar shape. In the third embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

The first stent body <NUM> of the third embodiment is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the radial direction RD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

The outer cell <NUM> includes, in the annular direction CD1, a pair of struts (first struts) <NUM> (hereinafter also referred to as "211a to 211b") and a strut (first strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the outer cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The ratio of a clearance L1 between the pair of struts 211a to 211b to the clearance L2 of the hole <NUM> is about <NUM>:<NUM> to <NUM>:<NUM>, for example. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain outer cell <NUM> is one strut 211a of the pair of struts <NUM> in another outer cell <NUM> adjacent to the certain outer cell <NUM> in the annular direction CD1.

In the outer cell <NUM>, the hole <NUM> is formed. In each outer cell <NUM> arranged along the annular direction CD1, the pair of struts 211a to 211b and struts <NUM> extending along the annular direction CD1 are connected to each other at intersections <NUM>.

The second stent body <NUM> of the third embodiment is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

The inner cell <NUM> includes, in the annular direction CD1, a pair of struts (second struts) <NUM> (hereinafter also referred to as "221a to 221b") and one strut (second strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the inner cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The ratio of a clearance L3 between the pair of struts 221a to 221b to the clearance L4 of the hole <NUM> is about <NUM>:<NUM> to <NUM>:<NUM>, for example. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain inner cell <NUM> is one strut 221a of the pair of struts <NUM> in another inner cell <NUM> adjacent to the certain inner cell <NUM> in the annular direction CD1.

In the inner cell <NUM>, the hole <NUM> is formed. In each inner cell <NUM> arranged along the annular direction CD1, the pair of struts 221a to 221b and struts <NUM> extending along the annular direction CD1 are connected to each other at intersections <NUM>.

In the stent 1B of the third embodiment, the plurality of outer cells <NUM> forming the first stent body <NUM> and the plurality of inner cells <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the third embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent 1B, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. In a case where each stent body is configured, as in the third embodiment, with the cell shape shown in <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1B can be more increased.

Next, other advantageous effects of the stent 1B of the third embodiment will be described. <FIG> is a sectional view in a case where the stent 1A of the above-described second embodiment is expanded in a blood vessel. <FIG> virtually shows the section of the stent 1A expanded in the blood vessel, for example, in a case where the stent 1A is diagonally cut along an s2-s2 line of <FIG>. <FIG> is a sectional view in a case where the stent 1B of the third embodiment is expanded in a blood vessel. <FIG> virtually shows the section of the stent 1B expanded in the blood vessel, for example, in a case where the stent 1B is diagonally cut along an s3-s3 line of <FIG>.

When the stent 1A of the second embodiment is expanded in a blood vessel BV as shown in <FIG>, the struts <NUM> forming the outer cells <NUM> of the first stent body <NUM> and the struts <NUM> forming the inner cells <NUM> of the second stent body <NUM> are alternately arranged in a circumferential direction. Thus, the section of the opening of the stent 1A is in a shape greatly corrugated along the circumferential direction and having large steps. Note that the "circumferential direction" in description of <FIG> means a circumferential direction when the stent is viewed in the axial direction (center axis direction).

On the other hand, when the stent 1B of the third embodiment is expanded in the blood vessel BV as shown in <FIG>, the pairs of struts <NUM> (211a to 211b: see <FIG>) forming the outer cells <NUM> of the first stent body <NUM> and the pairs of struts <NUM> (221a to 221b: see <FIG>) forming the inner cells <NUM> of the second stent body <NUM> are alternately arranged along the circumferential direction. Thus, the section of the opening of the stent 1B is in a shape less corrugated along the circumferential direction and having smaller steps. As described above, since the stent 1B of the third embodiment is less corrugated in the section of the opening, the stent 1B can be expanded in a shape closer to a circular shape. Thus, according to the stent 1B of the third embodiment, an inner wall of the narrowed blood vessel BV can be more uniformly expanded.

Next, a stent 1C of a fourth embodiment will be described. The stent 1C of the fourth embodiment is different from that of the third embodiment in the cell shapes of first and second stent bodies. Thus, in description and drawings of the fourth embodiment, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the third embodiment, and overlapping description thereof will be omitted as necessary. In the fourth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

<FIG> is a schematic perspective view of the stent 1C of the fourth embodiment. <FIG> is a development view showing a state in which a first stent body <NUM> of the fourth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the fourth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1C of the fourth embodiment is virtually opened in a planar shape.

As shown in <FIG>, the stent 1C of the fourth embodiment includes the first stent body <NUM> and the second stent body <NUM>. The first stent body <NUM> is a substantially cylindrical structure arranged outside the stent 1C. The second stent body <NUM> is a substantially cylindrical structure arranged inside the first stent body <NUM>. The stent 1C has such a double-layer structure in which the second stent body <NUM> is inserted into the first stent body <NUM>. Note that <FIG> does not show the push wire <NUM> and the distal end shaft <NUM> shown in <FIG>.

The first stent body <NUM> is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the radial direction RD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

The outer cell <NUM> includes, in the annular direction CD1, a pair of struts (first struts) <NUM> (hereinafter also referred to as "311a to 311b") and one strut (first strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the outer cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain outer cell <NUM> is one strut 311a of the pair of struts <NUM> in another outer cell <NUM> adjacent to the certain outer cell <NUM> in the annular direction CD1.

In the outer cell <NUM>, the hole <NUM> is formed. In each outer cell <NUM> arranged along the annular direction CD1, the pair of struts 311a to 311b and struts <NUM> extending along the annular direction CD1 are connected to each other at substantially S-shaped first intersections <NUM>. The first intersection <NUM> deforms so as to stretch in the radial direction RD when the expanded stent 1C is bent substantially in a U-shape (see <FIG>). Thus, the outer cells <NUM> spread in the radial direction RD can be more flexibly bent. As shown in <FIG>, in the first stent body <NUM>, the first intersections <NUM> are arranged in parallel in the radial direction RD.

The second stent body <NUM> is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

The inner cell <NUM> includes, in the annular direction CD1, a pair of struts (second struts) <NUM> (hereinafter also referred to as "321a to 321b") and one strut (second strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the inner cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain inner cell <NUM> is one strut 321a of the pair of struts <NUM> in another inner cell <NUM> adjacent to the certain inner cell <NUM> in the annular direction CD1.

In the inner cell <NUM>, the hole <NUM> is formed. In each inner cell <NUM> arranged along the annular direction CD1, the pair of struts 321a to 321b and struts <NUM> extending along the annular direction CD1 are connected to each other at substantially S-shaped second intersections <NUM>. The second intersection <NUM> deforms so as to stretch in the radial direction RD when the expanded stent 1C is bent substantially in the U-shape (see <FIG>). Thus, the inner cells <NUM> spread in the radial direction RD can be more flexibly bent. As shown in <FIG>, in the second stent body <NUM>, the second intersections <NUM> are arranged in parallel in the radial direction RD.

In the stent 1C of the fourth embodiment, the plurality of outer cells <NUM> forming the first stent body <NUM> and the plurality of inner cells <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the fourth embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent 1C, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the second intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the second intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one second intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. In a case where each stent body is configured, as in the fourth embodiment, with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1C can be more increased.

In the stent 1C of the fourth embodiment, the outer cells <NUM> of the first stent body <NUM> are connected, in the annular direction CD1, to each other at the substantially S-shaped first intersections <NUM>. Similarly, the inner cells <NUM> of the second stent body <NUM> are connected, in the annular direction CD2, to each other at the substantially S-shaped second intersections <NUM>. The first intersections <NUM> of the first stent body <NUM> and the second intersections <NUM> of the second stent body <NUM> are arranged in parallel in the radial direction RD, as shown in <FIG>. According to the present configuration, the outer cells <NUM> and the inner cells <NUM> spread in the radial direction RD can be more flexibly bent when the expanded stent 1C is bent substantially in the U-shape (see <FIG>), and therefore, the shape followability of the stent 1C can be more enhanced.

Next, a stent 1D of a fifth embodiment will be described. The stent 1D of the fifth embodiment is different from that of the third embodiment in the cell shapes of first and second stent bodies. Thus, in description and drawings of the fifth embodiment, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the third embodiment, and overlapping description thereof will be omitted as necessary. In the fifth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

<FIG> is a schematic perspective view of the stent 1D of the fifth embodiment. <FIG> is a development view showing a state in which a first stent body <NUM> of the fifth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the fifth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1D of the fifth embodiment is virtually opened in a planar shape.

As shown in <FIG>, the stent 1D of the fifth embodiment includes the first stent body <NUM> and the second stent body <NUM>. The first stent body <NUM> is a substantially cylindrical structure arranged outside the stent 1D. The second stent body <NUM> is a substantially cylindrical structure arranged inside the first stent body <NUM>. The stent 1D has such a double-layer structure in which the second stent body <NUM> is inserted into the first stent body <NUM>. Note that <FIG> does not show the push wire <NUM> and the distal end shaft <NUM> shown in <FIG>.

The first stent body <NUM> of the fifth embodiment is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the radial direction RD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

In the fifth embodiment, the configuration of the first stent body <NUM> is substantially the same as that of the first stent body <NUM> of the fourth embodiment, and therefore, detailed description thereof will be omitted. In the first stent body <NUM> of the fifth embodiment, struts <NUM>, 411a, 411b, the outer cell <NUM>, a hole <NUM>, and a first intersection <NUM> are equivalent to the struts <NUM>, 311a, 311b, the outer cell <NUM>, the hole <NUM>, and the first intersection <NUM> of the first stent body <NUM> of the fourth embodiment. As shown in <FIG>, the outer cells <NUM> of the first stent body <NUM> are connected to each other at the first intersections <NUM> in the annular direction CD1.

The second stent body <NUM> of the fifth embodiment is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> spreads in the radial direction (circumferential direction) RD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD.

The inner cell <NUM> includes, in the annular direction CD2, a pair of struts (second struts) <NUM> (hereinafter also referred to as "421a to 421b") and one strut (second strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the inner cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD2 in a certain inner cell <NUM> is one strut 421a of the pair of struts <NUM> in another inner cell <NUM> adjacent to the certain inner cell <NUM> in the annular direction CD2.

In the inner cell <NUM>, the hole <NUM> is formed. In each inner cell <NUM> arranged along the annular direction CD2, the pair of struts 421a to 421b and struts <NUM> extending along the annular direction CD2 are connected to each other at substantially S-shaped second intersections <NUM>. The second intersection <NUM> deforms so as to stretch in the radial direction RD when the expanded stent 1D is bent substantially in a U-shape (see <FIG>). Thus, the inner cells <NUM> spread in the radial direction RD can be more flexibly bent.

As shown in <FIG>, the inner cells <NUM> of the second stent body <NUM> are connected, in the annular direction CD2, to each other at the second intersections <NUM>. Thus, in the stent 1D of the fifth embodiment, the annular direction CD1 in which the outer cells <NUM> of the first stent body <NUM> are connected to each other at the first intersections <NUM> (see <FIG>) and the annular direction CD2 in which the inner cells <NUM> of the second stent body <NUM> are connected to each other at the second intersections <NUM> are symmetrical with respect to a line along the radial direction RD.

As shown in <FIG>, in the stent 1D, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the second intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the second intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one second intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. Moreover, in the stent 1D, the first intersections <NUM> of the outer cells <NUM> and the second intersections <NUM> of the inner cells <NUM> are arranged in parallel in the radial direction RD, and are arranged alternately. In a case where each stent body is configured with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1D can be more increased.

Further, in the stent 1D of the fifth embodiment, the outer cells <NUM> of the first stent body <NUM> are connected, in the annular direction CD1, to each other at the substantially S-shaped first intersections <NUM>. On the other hand, the inner cells <NUM> of the second stent body <NUM> are connected, in the annular direction CD2, to each other at the substantially S-shaped second intersections <NUM>. The first intersections <NUM> of the first stent body <NUM> and the second intersections <NUM> of the second stent body <NUM> are arranged in parallel in the radial direction RD, as shown in <FIG>. According to the present configuration, the outer cells <NUM> and the inner cells <NUM> spread in the radial direction RD can be more flexibly bent when the expanded stent 1D is bent substantially in the U-shape (see <FIG>), and therefore, the shape followability of the stent 1D can be more enhanced.

Next, a stent 1E of a sixth embodiment will be described. The stent 1E of the sixth embodiment is different from that of the third embodiment in the cell shapes of first and second stent bodies. Thus, in description and drawings of the sixth embodiment, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the third embodiment, and overlapping description thereof will be omitted as necessary. In the sixth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

<FIG> is a schematic perspective view of the stent 1E of the sixth embodiment. <FIG> is a development view showing a state in which a first stent body <NUM> of the sixth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the sixth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1E of the sixth embodiment is virtually opened in a planar shape. In the sixth embodiment, a circumferential direction OD is inclined with respect to the radial direction RD.

As shown in <FIG>, the stent 1E of the sixth embodiment includes the first stent body <NUM> and the second stent body <NUM>. The first stent body <NUM> is a substantially cylindrical structure arranged outside the stent 1E. The second stent body <NUM> is a substantially cylindrical structure arranged inside the first stent body <NUM>. The stent 1E of the sixth embodiment has such a double-layer structure in which the second stent body <NUM> is inserted into the first stent body <NUM>. Note that <FIG> does not show the push wire <NUM> and the distal end shaft <NUM> shown in <FIG>.

The first stent body <NUM> is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> spreads in the circumferential direction OD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the circumferential direction OD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the circumferential direction OD and is continuously arranged in the axial direction LD.

The outer cell <NUM> includes, in the annular direction CD1, a pair of struts (first struts) <NUM> (hereinafter also referred to as "511a to 511b") and one strut (first strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the outer cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain outer cell <NUM> is one strut 511a of the pair of struts <NUM> in another outer cell <NUM> adjacent to the certain outer cell <NUM> in the annular direction CD1.

The pair of struts 511a to 511b and one strut <NUM> arranged in the annular direction CD1 form the long sides of the outer cell <NUM>. Two struts <NUM> arranged in the annular direction CD2 form the short sides of the outer cell <NUM>. The outer cell <NUM> is configured, when opened in a planar shape, such that the long-side struts 511a to 511b, <NUM> and the short-side struts <NUM> are diagonally coupled substantially in the form of a parallelogram.

In the outer cell <NUM>, the hole <NUM> is formed. In each outer cell <NUM> arranged along the annular direction CD1, the pair of struts 511a to 511b and the struts <NUM> extending along the annular direction CD1 are connected at substantially S-shaped first intersections <NUM>. The first intersection <NUM> deforms so as to stretch in the radial direction RD when the expanded stent 1E is bent substantially in a U-shape (see <FIG>). Thus, the outer cells <NUM> spread in the radial direction RD can be more flexibly bent. As shown in <FIG>, in the first stent body <NUM>, the first intersections <NUM> are arranged in parallel in the circumferential direction OD.

The second stent body <NUM> is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> spreads in the circumferential direction OD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the circumferential direction OD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the circumferential direction OD and is continuously arranged in the axial direction LD.

The inner cell <NUM> includes, in the annular direction CD1, a pair of struts (second struts) <NUM> (hereinafter also referred to as "521a to 521b") and one strut (second strut) <NUM> arranged with a clearance (a hole <NUM>) from the pair of struts <NUM>. Moreover, the inner cell <NUM> includes, in the annular direction CD2, two struts <NUM> arranged with a clearance (the hole <NUM>) therebetween so as to face each other. The strut <NUM> arranged apart from the pair of struts <NUM> in the annular direction CD1 in a certain inner cell <NUM> is one strut 521a of the pair of struts <NUM> in another inner cell <NUM> adjacent to the certain inner cell <NUM> in the annular direction CD1.

The pair of struts 521a to 521b and one strut <NUM> arranged in the annular direction CD1 form the long sides of the inner cell <NUM>. Two struts <NUM> arranged in the annular direction CD2 form the short sides of the inner cell <NUM>. The inner cell <NUM> is configured, when opened in a planar shape, such that the long-side struts 521a to 521b, <NUM> and the short-side struts <NUM> are diagonally coupled substantially in the form of a parallelogram.

In the inner cell <NUM>, the hole <NUM> is formed. In each inner cell <NUM> arranged along the annular direction CD1, the pair of struts 521a to 521b and the struts <NUM> extending along the annular direction CD1 are connected at substantially S-shaped second intersections <NUM>. The second intersection <NUM> deforms so as to stretch in the radial direction RD when the expanded stent 1E is bent substantially in the U-shape (see <FIG>). Thus, the inner cells <NUM> spread in the radial direction RD can be more flexibly bent. As shown in <FIG>, in the second stent body <NUM>, the second intersections <NUM> are arranged in parallel in the circumferential direction OD.

As shown in <FIG>, in the stent 1E, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the second intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the second intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one second intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. Moreover, in the stent 1E, the first intersections <NUM> of the outer cells <NUM> and the second intersections <NUM> of the inner cells <NUM> are arranged in parallel in the circumferential direction OD, and are arranged alternately. In a case where each stent body is configured with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1E can be more increased.

Further, in the stent 1E of the sixth embodiment, the outer cells <NUM> of the first stent body <NUM> are connected, in the annular direction CD1, to each other at the substantially S-shaped first intersections <NUM>. Similarly, the inner cells <NUM> of the second stent body <NUM> are connected, in the annular direction CD1, to each other at the substantially S-shaped second intersections <NUM>. The first intersections <NUM> of the first stent body <NUM> and the second intersections <NUM> of the second stent body <NUM> are arranged in parallel in the circumferential direction OD, as shown in <FIG>. According to the present configuration, the outer cells <NUM> and the inner cells <NUM> spread in the circumferential direction OD can be more flexibly bent when the expanded stent 1E is bent substantially in the U-shape (see <FIG>), and therefore, the shape followability of the stent 1E can be more enhanced.

<FIG> is a side view schematically showing a configuration in which a proximal side end portion of a stent <NUM> and a push wire <NUM> are connected in a first connection form. <FIG> is a sectional view along an s4-s4 line of <FIG>. Note that in description of a seventh embodiment and laterdescribed eighth and ninth embodiments, the stent <NUM> (see <FIG>) of the first embodiment will be described as an example of a stent for describing a connection form, but the connection form may be applied to stents of other embodiments. Moreover, in each figure described below, the configuration of the stent <NUM> is simplified.

As shown in <FIG>, a proximal side LD1 end portion <NUM> of the first stent body <NUM> is connected, at a connection portion <NUM>, to the push wire <NUM>. A proximal side LD1 end portion <NUM> of the second stent body <NUM> is connected, at a connection portion <NUM>, to the push wire <NUM>. In the first connection form, the connection portion <NUM> of the first stent body <NUM> and the connection portion <NUM> of the second stent body <NUM> are provided at the same position in the axial direction LD of the push wire <NUM>. Positions at which the connection portion <NUM> of the first stent body <NUM> and the connection portion <NUM> of the second stent body <NUM> are connected by, e.g., welding and the areas thereof are schematically shown.

As shown in <FIG>, the connection portions <NUM> of the first stent body <NUM> and the connection portions <NUM> of the second stent body <NUM> are provided at equal intervals in the radial direction (the direction perpendicular to the axial direction LD) of the push wire <NUM>. Note that <FIG> shows the example where the connection portions <NUM> of the first stent body <NUM> and the connection portions <NUM> of the second stent body <NUM> are provided at an interval of <NUM> degrees in the circumferential direction, but the present invention is not limited to this example.

<FIG> is a side view schematically showing a configuration in which the proximal side end portion of the stent <NUM> and the push wire <NUM> are connected in a second connection form. <FIG> is a sectional view along an s5-s5 line of <FIG>. <FIG> is a sectional view along an s6-s6 line of <FIG>. For the sake of easy recognition of the position of each connection portion in <FIG> and <FIG>, the up-down direction in the figure will be referred to as a first radial direction RD1, and the right-left direction, which is perpendicular to the first radial direction RD1, in the figure will be referred to as a second radial direction RD2. Note that the first radial direction RD1 and the second radial direction RD2 are not limited to the up-down direction and the right-left direction in the drawing.

As shown in <FIG>, the proximal side LD1 end portion <NUM> of the first stent body <NUM> and the proximal side LD1 end portion <NUM> of the second stent body <NUM> are connected at different positions in the axial direction LD of the push wire <NUM>. Specifically, the end portion <NUM> of the first stent body <NUM> extends from the distal side LD2 to proximal side LD1 along the side surface of the push wire <NUM>. Moreover, the end portion <NUM> of the first stent body <NUM> is connected at the connection portion <NUM> on the proximal side LD1 with respect to the connection portion <NUM> of the second stent body <NUM>. On the other hand, the end portion <NUM> of the second stent body <NUM> is positioned on the distal side LD2 of the push wire <NUM>. Moreover, the end portion <NUM> of the second stent body <NUM> is connected at the connection portion <NUM> on the distal side LD2 with respect to the end portion <NUM> of the first stent body <NUM>.

The connection portions <NUM> of the first stent body <NUM> and the connection portions <NUM> of the second stent body <NUM> are provided at equal intervals as viewed in the axial direction LD of the push wire <NUM>. For example, as shown in <FIG>, the connection portions <NUM> of the second stent body <NUM> are provided at an interval of <NUM> degrees in the first radial direction RD1. In <FIG>, the end portion <NUM> of the first stent body <NUM> contacts the side surface of the push wire <NUM>, but is not connected at the connection portion <NUM>. Moreover, as shown in <FIG>, the connection portions <NUM> of the first stent body <NUM> are provided at an interval of <NUM> degrees in the second radial direction RD2.

According to the configuration of the present embodiment, in the axial direction LD of the push wire <NUM>, the end portion <NUM> of the first stent body <NUM> and the end portion <NUM> of the second stent body <NUM> are not connected at the same position. Thus, a defect such as distortion of the push wire <NUM> due to heat upon welding can be reduced. Note that in the axial direction LD of the push wire <NUM>, the positions of the connection portion <NUM> of the first stent body <NUM> and the connection portion <NUM> of the second stent body <NUM> may be switched such that the connection portion <NUM> of the first stent body <NUM> is provided on the distal side LD2 with respect to the connection portion <NUM> of the second stent body <NUM>.

<FIG> is a side view schematically showing a configuration in which the proximal side end portion of the stent <NUM> and the push wire <NUM> are connected in a third connection form. <FIG> is a sectional view along an s7-s7 line of <FIG>. <FIG> is a sectional view along an s8-s8 line of <FIG>. For the sake of easy recognition of the position of each connection portion in <FIG>, the up-down direction in the figure will be referred to as a first radial direction RD1, and the right-left direction, which is perpendicular to the first radial direction RD1, in the figure will be referred to as a second radial direction RD2, as in the eighth embodiment.

As shown in <FIG>, the end portion <NUM> of the first stent body <NUM> and the end portion <NUM> of the second stent body <NUM> are connected at different positions in the axial direction LD of the push wire <NUM>. Specifically, the end portion <NUM> of the first stent body <NUM> extends from the distal side LD2 to the proximal side LD1 over the end portion <NUM> of the second stent body <NUM>. Moreover, the end portion <NUM> of the first stent body <NUM> is connected at the connection portion <NUM> on the proximal side LD1 with respect to the end portion <NUM> of the second stent body <NUM>. On the other hand, the end portion <NUM> of the second stent body <NUM> is positioned on the distal side LD2 of the push wire <NUM>. Moreover, the end portion <NUM> of the second stent body <NUM> is connected at the connection portion <NUM> on the distal side LD2 with respect to the end portion <NUM> of the first stent body <NUM>.

The connection portions <NUM> of the first stent body <NUM> and the connection portions <NUM> of the second stent body <NUM> are provided at equal intervals as viewed in the axial direction LD of the push wire <NUM>. For example, as shown in <FIG>, the connection portions <NUM> of the second stent body <NUM> are provided at an interval of <NUM> degrees in the first radial direction RD1. Moreover, as shown in <FIG>, the connection portions <NUM> of the first stent body <NUM> are provided at an interval of <NUM> degrees in the first radial direction RD1, as in the connection portion <NUM> of the second stent body <NUM>.

Note that in the axial direction LD of the push wire <NUM>, the positions of the connection portion <NUM> of the first stent body <NUM> and the connection portion <NUM> of the second stent body <NUM> may be switched such that the connection portion <NUM> of the first stent body <NUM> is provided on the distal side LD2 with respect to the connection portion <NUM> of the second stent body <NUM>. Moreover, in <FIG>, the connection portions <NUM> of the second stent body <NUM> may be provided at an interval of <NUM> degrees in the second radial direction RD2, and the connection portions <NUM> of the first stent body <NUM> may be provided at an interval of <NUM> degrees in the second radial direction RD2.

The connection forms of the proximal side end portion of the stent <NUM> and the push wire <NUM> as described above in the seventh to ninth embodiments are also applicable to a connection form of the distal side LD2 of the stent <NUM> and the distal end shaft <NUM>. <FIG> is a side view schematically showing a configuration in which the distal side end portion of the stent <NUM> and the distal end shaft <NUM> are connected in the first connection form (the seventh embodiment).

As shown in <FIG>, a distal side LD2 end portion <NUM> of the first stent body <NUM> is connected, at a connection portion <NUM>, to the distal end shaft <NUM>. A distal side LD2 end portion <NUM> of the second stent body <NUM> is connected, at a connection portion <NUM>, to the distal end shaft <NUM>. The connection portion <NUM> of the first stent body <NUM> and the connection portion <NUM> of the second stent body <NUM> are provided at the same position in the axial direction LD of the distal end shaft <NUM>. Although not shown in the figure, the connection portions <NUM> of the first stent body <NUM> and the connection portions <NUM> of the second stent body <NUM> are provided at equal intervals as viewed in the axial direction LD of the distal end shaft <NUM> (see, e.g., <FIG>).

<FIG> is a side view schematically showing another configuration in which the distal side end portion of the stent <NUM> and the distal end shaft <NUM> are connected in the first connection form (see <FIG>). As shown in <FIG>, it may be configured such that a metal wire <NUM> having a high radiopacity is inserted into the stent <NUM>. A distal side LD2 end portion of the metal wire <NUM> is connected to the distal end shaft <NUM>. Although not shown in the figure, a proximal side LD1 end portion of the metal wire <NUM> is connected to the push wire <NUM> (see <FIG>).

<FIG> is a side view schematically showing a configuration in which the distal side end portion of the stent <NUM> and the distal end shaft <NUM> are connected in a fourth connection form. As shown in <FIG>, the distal side LD2 end portion <NUM> of the second stent body <NUM> is connected, at the connection portion <NUM>, to the distal end shaft <NUM>. On the other hand, the distal side LD2 end portion of the first stent body <NUM> is not connected to the distal end shaft <NUM>. That is, in the fourth connection form, only the distal side LD2 end portion <NUM> of the second stent body <NUM> on the distal side of the stent <NUM> is connected to the distal end shaft <NUM>. Note that it may be configured such that in the fourth connection form shown in <FIG>, only the distal side LD2 end portion <NUM> of the first stent body <NUM> on the distal side of the stent <NUM> is connected to the distal end shaft <NUM>.

<FIG> is a side view schematically showing another configuration of the stent <NUM> on the distal side thereof. As shown in <FIG>, it may be configured such that the first stent body <NUM> and the second stent body <NUM> are opened on the distal side LD2. Note that although not shown in the figure, the proximal side LD1 end portion of the first stent body <NUM> and the proximal side LD1 end portion of the second stent body <NUM> are connected to the push wire <NUM> (see <FIG>) in the configuration shown in <FIG>.

<FIG> is a schematic side view of a stent 1F of an eleventh embodiment. <FIG> is a sectional view along an s9-s9 line of <FIG>. In description and drawings of the eleventh embodiment, the same reference numerals as those of the first embodiment are used to represent members etc. similar to those of the first embodiment, and overlapping description thereof will be omitted. As shown in <FIG> and <FIG>, the stent 1F of the eleventh embodiment includes a coating film <NUM> between a first stent body <NUM> and a second stent body <NUM>. The coating film <NUM> is provided substantially in a cylindrical shape, and extends along the axial direction LD of the stent 1F. For the coating film <NUM>, a material such as PTFE or ePTFE may be used, for example. The thickness of the coating film <NUM> is, for example, about <NUM> to <NUM>.

The coating film <NUM> is provided between the first stent body <NUM> and the second stent body <NUM> so that infarction in a distal side blood vessel due to, e.g., leakage of plaque or blood clot through a clearance among struts (see <FIG>) can be reduced. The coating film <NUM> is not necessarily provided between the first stent body <NUM> and the second stent body <NUM>, but may be provided outside the first stent body <NUM>.

The coating film <NUM> may contain a medical agent. The coating film <NUM> containing the medical agent indicates that the coating film <NUM> releasably carries the medical agent so as to dissolve out the medical agent. The medical agent is not limited, and for example, may include the medical agents described as examples in the configuration of the stent <NUM> of the first embodiment containing the medical agent. The coating film <NUM> may be made of an antithrombogenic material having a blood coagulation inhibition function.

Next, an embodiment in which a strand having a high radiopacity is wound around a stent will be described. In the present embodiment, the stent <NUM> (see <FIG>) of the first embodiment will be described as an example of the stent around which the strand having the high radiopacity is wound, but this configuration may be applied to stents of other embodiments. <FIG> is a schematic view showing an example where a strand <NUM> (hereinafter also referred to as a "strand <NUM>") having a high radiopacity is sparsely wound around the strut <NUM> of the first stent body <NUM>. In the example shown in <FIG>, the strand <NUM> may be wound around all the struts <NUM> of the first stent body <NUM>, or be wound around only some of the struts <NUM>.

<FIG> is a schematic view showing an example where the strand <NUM> having the high radiopacity is densely wound (in a coil shape) around the strut <NUM> of the first stent body <NUM>. In the example shown in <FIG>, the strand <NUM> may be wound around all the struts <NUM> of the first stent body <NUM>, or be wound around only some of the struts <NUM>.

Note that in the examples shown in <FIG> and <FIG>, the strand <NUM> may be wound around the struts <NUM> of the second stent body <NUM> in a similar form. The strand <NUM> may be wound around both the first stent body <NUM> and the second stent body <NUM>, or be wound around only either one of the first stent body <NUM> or the second stent body <NUM>.

<FIG> is a schematic view showing an example where the strand <NUM> having the high radiopacity is wound around the stent <NUM> in a first form. As shown in <FIG>, in the first form, the strand <NUM> is wound around the second stent body <NUM>, which is positioned inside the stent <NUM>, in a spiral shape. One end portion 31a of the strand <NUM> is connected to the proximal side LD1 of the second stent body <NUM>. The other end portion 31b of the strand <NUM> is connected to the distal side LD2 of the second stent body <NUM>. The strand <NUM> is wound around the second stent body <NUM> in the spiral shape so that the visibility of the stent <NUM> expanded in a blood vessel on an X-ray transparent image can be enhanced. Note that a plurality of strands <NUM> may be wound. In a case where the plurality of strands <NUM> is wound, it can be checked whether or not the stent <NUM> expanded in the blood vessel is partially opened.

The strand <NUM> may be connected to the strut <NUM> (see <FIG>) of the second stent body <NUM> by, e.g., welding. The strand <NUM> is not necessarily connected to the second stent body <NUM>, but may be connected to the first stent body <NUM> positioned outside the stent <NUM> or be connected to different stent bodies. For example, it may be configured such that one end portion of the strand <NUM> is connected to the proximal side LD1 of the second stent body <NUM> and the other end portion is connected to the distal side LD2 of the first stent body <NUM>.

<FIG> is a schematic view showing an example where the strand <NUM> having the high radiopacity is wound around the stent <NUM> in a second form. As shown in <FIG>, in the second form, the strand <NUM> is wound around the second stent body <NUM> in a spiral shape so as to extend back and forth between both end portions of the second stent body <NUM>. One end portion of the strand <NUM> is connected to the proximal side LD1 of the second stent body <NUM>. The strand <NUM> is wound around the second stent body <NUM> in the spiral shape from the proximal side LD1 to the distal side LD2 of the stent <NUM>. The strand <NUM> is folded back at the distal side LD2 end portion of the second stent body <NUM>, and is wound around the second stent body <NUM> in the spiral shape from the distal side LD2 to the proximal side LD1 of the stent <NUM>. The other end portion of the strand <NUM> is connected to the proximal side LD1 of the second stent body <NUM>. In the second form shown in <FIG>, advantageous effects similar to those of the above-described first embodiment can be obtained.

In the present form, the strand <NUM> may be connected to the strut <NUM> of the second stent body <NUM> by, e.g., welding. The strand <NUM> is not necessarily connected to the second stent body <NUM>, but may be connected to the first stent body <NUM> positioned outside the stent <NUM> or be connected to different stent bodies. For example, it may be configured such that one end portion of the strand <NUM> is connected to the proximal side LD1 of the second stent body <NUM> and the other end portion is connected to the distal side LD2 of the first stent body <NUM>.

Next, a stent <NUM> of a thirteenth embodiment will be described. The stent <NUM> of the thirteenth embodiment is different from that of the first embodiment in the cell shapes of first and second stent bodies. Other configurations of the stent <NUM> of the thirteenth embodiment are the same as those of the first embodiment. In description below and the drawings, the same reference numerals are used as end numerals (last two digits) of elements having functions similar to those of the first embodiment, and overlapping description thereof will be omitted as necessary.

<FIG> is a schematic perspective view of the stent <NUM> of the thirteenth embodiment. <FIG> is a development view showing a state in which part of a first stent body <NUM> of the thirteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which part of a second stent body <NUM> of the thirteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which part of the stent <NUM> of the thirteenth embodiment is virtually opened in a planar shape.

As shown in <FIG>, the stent <NUM> of the thirteenth embodiment includes the first stent body <NUM> and the second stent body <NUM>. The first stent body <NUM> is a substantially cylindrical structure arranged outside the stent <NUM>. The second stent body <NUM> is a substantially cylindrical structure arranged inside the first stent body <NUM>. The stent <NUM> has such a double-layer structure in which the second stent body <NUM> is inserted into the first stent body <NUM>. Note that <FIG> does not show the push wire <NUM> and the distal end shaft <NUM> shown in <FIG>.

The first stent body <NUM> is configured, as shown in <FIG>, such that a plurality of outer cells (first cells) <NUM> including struts <NUM> arranged in a frame shape spreads in a radial direction (circumferential direction) RD. In the first stent body <NUM>, the plurality of outer cells <NUM> spread in the radial direction RD is continuously arranged in an axial direction LD. That is, the first stent body <NUM> has such a mesh pattern that the plurality of outer cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD. In the outer cell <NUM>, a hole <NUM> is formed. Adjacent ones of the outer cells <NUM> in the radial direction RD are connected at an intersection <NUM>.

The intersection <NUM> is a portion where the struts <NUM> of adjacent four of the outer cells <NUM> are connected to each other. The intersection <NUM> has a substantially rectangular shape elongated in the axial direction LD. The struts <NUM> are each connected to four corners of the intersection <NUM>. Each strut <NUM> has a curved portion <NUM> at the portion connected to the intersection <NUM>. Thus, as compared to the intersecting point <NUM> (the outer cell <NUM>) of the first embodiment, the strut <NUM> is in a shape elongated in the axial direction LD at the intersection <NUM> (the outer cell <NUM>) of the present embodiment. Thus, when the expanded stent <NUM> is bent substantially in a U-shape (see <FIG>), the struts <NUM> connected to the intersection <NUM> are independently deformable. Thus, the outer cells <NUM> spread in the radial direction RD can be more flexibly bent. As described above, the outer cells <NUM> spread in the radial direction RD can be more flexibly bent, and therefore, the first stent body <NUM> has excellent shape followability and diameter reducibility.

The second stent body <NUM> is configured, as shown in <FIG>, such that a plurality of inner cells (second cells) <NUM> including struts <NUM> arranged in a frame shape spreads in the radial direction (circumferential direction) RD. In the second stent body <NUM>, the plurality of inner cells <NUM> spread in the radial direction RD is continuously arranged in the axial direction LD. That is, the second stent body <NUM> has such a mesh pattern that the plurality of inner cells <NUM> spreads in the radial direction RD and is continuously arranged in the axial direction LD. In the inner cell <NUM>, a hole <NUM> is formed. Adjacent ones of the inner cells <NUM> in the radial direction RD are connected at an intersection <NUM>.

The intersection <NUM> is a portion where the struts <NUM> of adjacent four of the inner cells <NUM> are connected to each other. The intersection <NUM> has a substantially rectangular shape elongated in the axial direction LD. The struts <NUM> are each connected to four corners of the intersection <NUM>. Each strut <NUM> has a curved portion <NUM> at the portion connected to the intersection <NUM>. Thus, as compared to the intersecting point <NUM> (the inner cell <NUM>) of the first embodiment, the strut <NUM> is in a shape elongated in the axial direction LD at the intersection <NUM> (the inner cell <NUM>) of the present embodiment. Thus, when the expanded stent <NUM> is bent substantially in the U-shape, the struts <NUM> connected to the intersection <NUM> are independently deformable in the radial direction RD. Thus, the inner cells <NUM> spread in the radial direction RD can be more flexibly bent. As described above, the inner cells <NUM> spread in the radial direction RD can be more flexibly bent, and therefore, the second stent body <NUM> has excellent shape followability and diameter reducibility.

As shown in <FIG> and <FIG>, in the stent <NUM> of the thirteenth embodiment, the outer cell <NUM> forming the first stent body <NUM> and the inner cell <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the thirteenth embodiment, the mesh pattern of the first stent body <NUM> shown in FIG. 13A and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. The mesh patterns of the stent bodies overlap with each other as described above, and therefore, the density of the mesh pattern is increased over the entire stent. Thus, the surface area of the stent <NUM> can be increased. The stent <NUM> of the present embodiment is configured such that the intersection <NUM> among the outer cells <NUM> has the configuration shown in <FIG> and the intersection <NUM> among the inner cells <NUM> has the configuration shown in <FIG>. Thus, the stent <NUM> has excellent shape followability and diameter reducibility. Moreover, the stent <NUM> is configured such that the outer cells <NUM> and the inner cells <NUM> have the configuration described above, and therefore, produces effects that the narrowed stent <NUM> is easily sheathed in a catheter and the stent <NUM> expanded in a blood vessel is easily resheathed in a catheter.

Next, a stent <NUM> of a fourteenth embodiment will be described. The stent <NUM> of the fourteenth embodiment is different from that of the fourth embodiment (see <FIG> and <FIG>) in the cell shapes of first and second stent bodies. Other configurations of the stent <NUM> of the fourteenth embodiment are the same as those of the fourth embodiment. Thus, in the fourteenth embodiment, the entirety of the stent <NUM> is not shown in the figure. In description and drawings of the fourteenth embodiment, the same reference numerals are used to represent elements having functions similar to those of the fourth embodiment, and overlapping description thereof will be omitted as necessary. In the fourteenth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

<FIG> is a development view showing a state in which a first stent body <NUM> of the fourteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the fourteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent <NUM> of the fourteenth embodiment is virtually opened in a planar shape.

The first stent body <NUM> of the fourteenth embodiment is different from that of the fourth embodiment in arrangement of first intersections <NUM>. As shown in <FIG>, the first stent body <NUM> of the fourteenth embodiment includes, in the annular direction CD1, a line C1 in which the first intersections <NUM> are arranged in every other position and a line C2 in which the first intersection <NUM> is arranged between each adjacent ones of the cells. The lines C1 and the lines C2 are alternately arranged in the annular direction CD2. Other configurations of the first stent body <NUM> of the fourteenth embodiment are the same as those of the fourth embodiment.

The second stent body <NUM> of the fourteenth embodiment is different from that of the fourth embodiment in arrangement of second intersections <NUM>. As shown in <FIG>, the second stent body <NUM> of the fourteenth embodiment includes, in the annular direction CD1, a line C3 in which the second intersections <NUM> are arranged in every other position and a line C4 in which the second intersection <NUM> is arranged between each adjacent ones of the cells. The lines C3 and the lines C4 are alternately arranged in the annular direction CD2. Other configurations of the second stent body <NUM> of the fourteenth embodiment are the same as those of the fourth embodiment.

In the stent <NUM> of the fourteenth embodiment, the plurality of outer cells <NUM> forming the first stent body <NUM> and the plurality of inner cells <NUM> forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the fourteenth embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent <NUM> of the fourteenth embodiment, in a line C5, the cells in each of which the second intersection <NUM> of the second stent body <NUM> is arranged in the hole <NUM> of the first stent body <NUM> and the cells in each of which no second intersection <NUM> is present in the hole <NUM> are alternately arranged in the annular direction CD1. In a line C6, the second intersection <NUM> of the second stent body <NUM> is arranged in the hole <NUM> of the first stent body <NUM> in the annular direction CD1. Moreover, in the stent <NUM> of the fourteenth embodiment, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the lines C5 and the lines C6 are alternately arranged in the annular direction CD2.

In a case where each stent body is configured, as in the fourteenth embodiment, with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent <NUM> can be more increased. In the stent <NUM> of the fourteenth embodiment, the outer cells <NUM> and the inner cells <NUM> spread in the radial direction RD can be more flexibly bent as in the stent 1C of the fourth embodiment when the expanded stent <NUM> is bent substantially in a U-shape (see <FIG>), and therefore, the shape followability of the stent <NUM> can be more enhanced.

Next, a stent 1J of a fifteenth embodiment will be described. The stent 1J of the fifteenth embodiment is different from that of the fourth embodiment (see <FIG> and <FIG>) in the cell shapes of first and second stent bodies. Other configurations of the stent 1J of the fifteenth embodiment are the same as those of the fourth embodiment. Thus, in the fifteenth embodiment, the entirety of the stent 1J is not shown in the figure. In description and drawings of the fifteenth embodiment, the same reference numerals are used to represent elements having functions similar to those of the fourth embodiment, and overlapping description thereof will be omitted as necessary. In the fifteenth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2.

<FIG> is a development view showing a state in which a first stent body <NUM> of the fifteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the fifteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent 1J of the fifteenth embodiment is virtually opened in a planar shape.

The first stent body <NUM> of the fifteenth embodiment is configured such that a plurality of outer cells <NUM> include outer cells 312J (described later) having a different configuration of a strut <NUM>. As shown in <FIG>, the first stent body <NUM> of the fifteenth embodiment includes the outer cells <NUM> (hereinafter also referred to as the "outer cells 312J") each of which has no strut 311b of a pair of struts 311a to 311b arranged in the annular direction CD1. In the outer cell 312J, a raised portion 314p is provided at a portion where an intersection <NUM> not connected to the strut 311b and the strut <NUM> extending in the annular direction CD1 are connected to each other. The raised portion 314p protrudes to the distal side LD2, and therefore, when the stent <NUM> expanded in a blood vessel is resheathed in a catheter, contact between the raised portion 314p and an end portion of the catheter can be reduced. Note that the outer cells 312J may be arranged regularly or irregularly in the first stent body <NUM>. Other configurations of the first stent body <NUM> of the fifteenth embodiment are the same as those of the fourth embodiment.

The second stent body <NUM> of the fifteenth embodiment is configured such that a plurality of inner cells <NUM> include inner cells 322J (described later) having a different configuration of a strut <NUM>. As shown in <FIG>, the second stent body <NUM> of the fifteenth embodiment includes the inner cells <NUM> (hereinafter also referred to as the "inner cells 322J") each of which has no strut 321b of a pair of struts 321a to 321b arranged in the annular direction CD1. In the inner cell 322J, a raised portion 324p is provided at a portion where an intersection <NUM> not connected to the strut 321b and the strut <NUM> extending in the annular direction CD1 are connected to each other. The raised portion 324p protrudes to the distal side LD2, and therefore, when the stent <NUM> expanded in a blood vessel is resheathed in a catheter, contact between the raised portion 324p and an end portion of the catheter can be reduced. Note that the inner cells 322J may be arranged regularly or irregularly. Other configurations of the second stent body <NUM> of the fifteenth embodiment are the same as those of the fourth embodiment.

In the stent 1J of the fifteenth embodiment, the plurality of outer cells <NUM> (including 312J) forming the first stent body <NUM> and the plurality of inner cells <NUM> (including 322J) forming the second stent body <NUM> have the same size, shape, and arrangement, as one example. That is, in the fifteenth embodiment, the mesh pattern of the first stent body <NUM> shown in <FIG> and the mesh pattern of the second stent body <NUM> shown in <FIG> are substantially the same pattern. Note that the mesh pattern of the first stent body <NUM> and the mesh pattern of the second stent body <NUM> may be different from each other.

As shown in <FIG>, in the stent 1J of the fifteenth embodiment, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that the second intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in a hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the second intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM> (312J), the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one second intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM> (312J).

In a case where each stent body is configured, as in the fifteenth embodiment, with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent 1J can be more increased. In the stent 1J of the fifteenth embodiment, the outer cells <NUM> (312J) and the inner cells <NUM> (322J) spread in the radial direction RD can be more flexibly bent as in the stent 1C of the fourth embodiment when the expanded stent 1J is bent substantially in a U-shape (see <FIG>), and therefore, the shape followability of the stent 1J can be more enhanced.

In the stent 1J of the fifteenth embodiment, the raised portion 314p of the first stent body <NUM> and the raised portion 324p of the second stent body <NUM> protrude to the distal side LD2. Thus, when the stent 1J expanded in a blood vessel is resheathed in a catheter, contact among the raised portions 314p, 324p and an end portion of the catheter can be reduced. Thus, according to the stent 1J of the fifteenth embodiment, the stent 1J expanded in the blood vessel can be smoothly resheathed in the catheter.

Next, a stent <NUM> of a sixteenth embodiment will be described. The stent <NUM> of the sixteenth embodiment is different from that of the fourth embodiment (see <FIG> and <FIG>) in the cell shapes of first and second stent bodies. Other configurations of the stent <NUM> of the sixteenth embodiment are the same as those of the fourth embodiment. Thus, in the sixteenth embodiment, the entirety of the stent <NUM> is not shown in the figure. In description and drawings of the sixteenth embodiment, the same reference numerals are used to represent elements having functions similar to those of the fourth embodiment, and overlapping description thereof will be omitted as necessary. In the sixteenth embodiment, annular directions of cells being connected diagonally to a radial direction (circumferential direction) RD will be referred to as annular directions CD1, CD2. In the sixteenth embodiment, the "cell" is not limited to one configured such that struts <NUM> are arranged in a frame shape, and may include forms (e.g., an outer cell <NUM> and an inner cell <NUM> described later) in which struts <NUM> are not arranged in a frame shape.

<FIG> is a development view showing a state in which a first stent body <NUM> of the sixteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which a second stent body <NUM> of the sixteenth embodiment is virtually opened in a planar shape. <FIG> is a development view showing a state in which the stent <NUM> of the sixteenth embodiment is virtually opened in a planar shape.

The first stent body <NUM> of the sixteenth embodiment is configured such that a plurality of outer cells <NUM> include the outer cells <NUM> (described later) having a different size. As shown in <FIG>, the first stent body <NUM> of the sixteenth embodiment includes the outer cells <NUM> (hereinafter also referred to as the "outer cells <NUM>") adjacent two of which in the annular direction CD2 has no common strut <NUM>. A hole <NUM> of the outer cell <NUM> has a size twice as large as holes <NUM> of the other outer cells <NUM>. Note that the outer cells <NUM> may be arranged regularly or irregularly in the first stent body <NUM>. Other configurations of the first stent body <NUM> of the sixteenth embodiment are the same as those of the fourth embodiment.

The second stent body <NUM> of the sixteenth embodiment is configured such that a plurality of inner cells <NUM> include the inner cells <NUM> (described later) having a different size. As shown in <FIG>, the second stent body <NUM> of the sixteenth embodiment includes the inner cells <NUM> (hereinafter also referred to as the "inner cells <NUM>") adjacent two of which in the annular direction CD2 has no common strut <NUM>. A hole <NUM> of the inner cell <NUM> has a size twice as large as holes <NUM> of the other inner cells <NUM>. Note that the inner cells <NUM> may be arranged regularly or irregularly in the second stent body <NUM>. Other configurations of the second stent body <NUM> of the sixteenth embodiment are the same as those of the fourth embodiment.

As shown in <FIG>, in the stent <NUM> of the sixteenth embodiment, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that a second intersection <NUM> between the inner cells <NUM> (of the second stent body <NUM>) is arranged in the hole <NUM> of the outer cell <NUM> (of the first stent body <NUM>). Specifically, in a configuration in which the second intersection <NUM> between the inner cells <NUM> is arranged in the hole <NUM> of the outer cell <NUM>, the first stent body <NUM> and the second stent body <NUM> overlap with each other such that one second intersection <NUM> between the inner cells <NUM> is arranged in one hole <NUM> of the outer cell <NUM>. Since the first stent body <NUM> and the second stent body <NUM> overlap with each other as described above, the stent <NUM> is in such a form that two second intersections <NUM> between the inner cells <NUM> are arranged in the hole <NUM> of the outer cell <NUM>.

In a case where each stent body is configured, as in the sixteenth embodiment, with the cell shape shown in <FIG> and <FIG>, the mesh patterns of the stent bodies overlap with each other as described above so that the density of the mesh pattern is increased over the entire stent and the surface area of the stent <NUM> can be more increased. In the stent <NUM> of the sixteenth embodiment, the outer cells <NUM> (<NUM>) and the inner cells <NUM> (<NUM>) spread in the radial direction RD can be more flexibly bent as in the stent 1C of the fourth embodiment when the expanded stent <NUM> is bent substantially in a U-shape (see <FIG>), and therefore, the shape followability of the stent <NUM> can be more enhanced.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments and various modifications and changes can be made. These modifications and changes are also included in the scope of the present invention. The advantageous effects described in the embodiments are merely listed as most-suitable advantageous effects of the present invention, and the advantageous effects are not limited to those described in the embodiments. Note that the above-described embodiments and various modified or changed configurations may be combined as necessary, but detailed description thereof will be omitted.

The stent <NUM> of the first embodiment has the double-layer structure of the first stent body <NUM> and the second stent body <NUM>, but is not limited to this structure. Another stent body may be further provided outside the first stent body <NUM> and/or inside the second stent body <NUM>. The same also applies to the stents of the other embodiments.

In the stent <NUM> of the first embodiment, the surface(s) of the first stent body <NUM> and/or the second stent body <NUM> may be coated with a medical agent or a carbon-based material coating film, or be coated with metal or polymer having a high radiopacity. Examples of the medical agent may include a medical agent used for the same purpose as that of a drugeluting stent (DES). Examples of the carbon-based material coating film may include an antithrombogenic inactive coating film such as diamond-like carbon (DLC). The same also applies to the stents of the other embodiments.

Claim 1:
A stent (<NUM>, 1A, 1B, 1C, 1D, 1E, 1F, <NUM>, <NUM>, 1J, <NUM>) that is inserted into a catheter and pushed out of the catheter in a blood vessel to expand the blood vessel, comprising:
a first stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) configured such that a plurality of first cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) including struts (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) arranged in a frame shape spreads in a circumferential direction (OD) and is continuously arranged in a center axis direction (LD); and
a second stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) configured such that a plurality of second cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) including struts (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) arranged in a frame shape spreads in a circumferential direction (OD) and is continuously arranged in a center axis direction (LD) and inserted into the first stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
wherein in a state in which the second stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is inserted into the first stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), an intersection (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) between the second cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is arranged in a hole (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) of each first cell (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
wherein in a diameter-expanded state, the first stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) closely contact each other and are not coupled to each other in a radial direction (RD) and,
wherein a proximal side end portion of the first stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a proximal side end portion of the second stent body (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are connected at different positions in an axial direction (LD) of a push wire (<NUM>).