JP2016193187A - High flexibility stent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stent which can suppress a deformation amount in a radial direction with respect to a torsion load.SOLUTION: The stent includes: wavy-line shaped pattern bodies 13 arranged in an axial direction LD; and plural coil-shaped elements 15 arranged between the adjacent wavy-line shaped pattern bodies 13 and extended in a spiral shape around an axis. In a view in a radial direction RD, an annular direction CD of the wavy-line shaped pattern body 13 is inclined with respect to the radial direction RD. The wavy-line shaped pattern body 13 is formed by wave shaped elements 17 connecting two leg parts 17a at an apex part 17b, having a general V-shape, and being connected plurally in a circumferential direction. The apex 17b of the wave shaped element 17 having the general V-shape is positioned between edges 171c, 172c on an opposite side to the apex 17b in the two leg parts 17a in the axial direction LD. A winding direction of one coil-shaped element 15 (15R) positioned on one side in the axial direction LD with respect to the wavy-line shaped pattern body 13 is reverse to a winding direction of the other coil-shaped element 15 (15L) positioned on the other side in the axial direction LD.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a highly flexible stent that is placed in the lumen structure of a living body to expand the lumen.

  In a living organ having a luminal structure such as a blood vessel, trachea, intestine, etc., when stenosis occurs, the reticular cylindrical stent is used to ensure the patency of the lesion site by expanding the stenotic lumen. used. These living organs often have a locally bent or tapered structure (that is, a tubular structure in which the lumen cross-sectional diameter is locally different in the axial direction). Highly conformable stents that can flexibly adapt to such complex vascular structures are desired. In recent years, stents have also been applied to cerebrovascular treatment. The cerebrovascular system has a complex structure among the tubular organs of a living body. In the cerebrovascular system, there are a large number of bent portions and portions having a tapered structure. Therefore, the stent requires a particularly high shape followability.

  In order to realize a stent with high shape followability, two types of mechanical flexibility in the axial direction (center axis direction) and the radial direction (direction perpendicular to the longitudinal axis) of the stent are important. Here, the flexibility in the axial direction means rigidity with respect to bending along the longitudinal axis or ease of bending. The flexibility in the radial direction means rigidity with respect to expansion / contraction in a direction perpendicular to the longitudinal axis or ease of expansion / contraction. Axial mechanical flexibility is a characteristic necessary to flexibly bend along the longitudinal axis and adapt to the bending site of a living tubular organ. Radial flexibility is a property required to flexibly change the radius of the stent along the shape of the outer wall of the luminal structure of the tubular organ of a living body so that the stent adheres to the outer wall of the luminal structure. In particular, with regard to the latter radial flexibility, not only the rigidity of the stent is lowered, but also in consideration of the fact that the stent is placed in a living organ having a tapered structure. Therefore, it is necessary to have such a characteristic that the expansion force of the stent does not change greatly with respect to the change in the lumen cross-sectional diameter.

  The structure of a stent is generally roughly classified into two types, an open cell type and a closed cell type. An open-cell stent exhibits a very flexible mechanical characteristic in the axial direction thereof, and thus has a high shape following ability and has been effective as a stent structure that is placed in a bent tubular organ. However, in such an open cell stent, there is a risk that a part of the stent struts may flared out in the radial direction of the stent when bent. Risk of tissue damage. On the other hand, some of the stents with a closed cell structure partially enable re-placement of an intraoperative stent, which was difficult with an open-cell structure stent, and others allow complete re-placement of an intraoperative stent. .

  Such a closed-cell stent does not have the risk of the stent struts popping out radially outside the stent unlike the open-cell stent, but tends to lack flexibility in its structure. Therefore, when a stent having a closed cell structure is applied to a bent tubular organ, there is a risk that the stent will buckle and obstruct the flow of liquid such as blood in the tubular organ. Furthermore, the closed-cell stent is structurally inferior to the open-cell stent in terms of diameter reduction. Therefore, the stent cannot be placed in a small-diameter tubular organ having a diameter of about 2 mm, and the living tissue is damaged. There was a risk of letting.

  In order to solve such a problem, a spiral stent has been devised as a technique that exhibits high flexibility while being a closed cell structure stent (see, for example, Patent Document 1). The stent of patent document 1 is provided with the helical annular body which has a wavy pattern, and the coil-shaped element which connects an adjacent annular body in the expansion | deployment state.

Special table 2010-535075 gazette

  By the way, for example, after placing the stent in the superficial femoral artery, the internal rotation and external rotation of the blood vessel occur by the internal rotation and external rotation of the thigh. Thereby, the stent in the blood vessel is also twisted in the internal rotation direction and the external rotation direction. However, in Patent Document 1, since the deformation form of the stent varies depending on the direction in which the stent is twisted, for example, the torsional deformation of the stent due to the internal rotation and external rotation of the blood vessel becomes uneven. Therefore, there is a difference in the load on the blood vessel wall of the stent between the left and right blood vessels. In particular, because the ratio of internal and external rotations on the left and right legs varies from person to person, for example, for patients with high frequency of internal rotation of both legs, if the stent is a stent that follows the internal rotation of the right leg The stent cannot follow the internal rotation of the left leg. As a result, the load on the blood vessel wall due to the stent differs between the left and right legs, so that the ratio of causing complications after placement of the stent differs between the left and right legs despite treatment with the same stent.

In addition, as described above, one leg, for example, the right foot, has an internal rotation and an external rotation, so that a stent that follows the internal rotation cannot follow the external rotation well. The above-mentioned problems cause the following clinical problems.
(1) The risk that the stent will break under repeated torsional loads increases.
(2) The risk of the blood vessel wall being damaged due to repeated stress concentration locally from the stent increases.

  In the stent of Patent Document 1, the coiled element can be approximately considered as a part of the structure of the winding spring. Moreover, when this stent receives a torsional load, deformation concentrates on the coiled element. For this reason, the response of the torsional deformation of the stent can be predicted by considering the torsional deformation of the spring structure of the coiled element.

  Here, the torsional deformation behavior in the case where deformation is considered using the coiled element in the deployed state of the stent of Patent Document 1 as a part of the left-handed spring structure will be described. When a left-handed spring is given a twist in the same winding direction (left-handed), a force is applied so that the spring is pulled in a direction perpendicular to the wire cross-section of the spring. Therefore, the strands are deformed so as to be wound in the circumferential direction, and exhibit a behavior of reducing the diameter in the radial direction. On the other hand, when a reverse winding (right winding) is twisted, a force acts so as to be compressed in the vertical direction with respect to the wire cross section of the spring. Therefore, the strands are deformed so as to be separated in the circumferential direction, and as a result, the outer diameter expands in the radial direction.

  Since the stent of Patent Document 1 is composed of a spring body, when it receives left and right twists, it exhibits a behavior similar to the twist deformation of the aforementioned wound spring. This deformation behavior changes the load on the blood vessel wall due to a large difference in the amount of deformation in the radial direction of the stent with respect to left and right twist deformation. Therefore, even if treatment is performed with the same stent as described above, there is a possibility that the treatment results may differ depending on the treatment target site and individual differences.

  In addition, the stent also has a problem of facilitating flexible bending deformation in the axial direction and suppressing shortening that improves bendability. Therefore, it is desired to improve the flexibility of the stent.

  Therefore, an object of the present invention is to provide a highly flexible stent that can suppress the amount of deformation of the stent in the radial direction against a torsional load and can improve the bendability of the stent.

  The present invention provides a plurality of wavy pattern bodies having a wavy pattern and arranged side by side in the axial direction, and a plurality of coil shapes that are arranged between adjacent wavy pattern bodies and extend spirally around the axis. A high-flexibility stent in which all of the crests on the opposite sides of the wavy pattern of adjacent wavy pattern bodies are connected to each other by the coil-shaped element, with respect to the axial direction When viewed in the perpendicular radial direction, the ring direction of the wavy pattern body is inclined with respect to the radial direction, and the wavy pattern body is substantially V-shaped with two legs connected at the top. A plurality of corrugated elements having a shape are connected in the circumferential direction, and the top of the substantially V-shaped corrugated element is the end of the two legs opposite to the top in the axial direction. Located between each other, said The winding direction of one of the coil-shaped elements positioned on one side in the axial direction with respect to the linear pattern body and the winding direction of the other coil-shaped element positioned on the other side in the axial direction are twisted by being opposite to each other. The present invention relates to a highly flexible stent that suppresses deformation in the stent radial direction with respect to a load.

  Further, in the substantially V-shaped corrugated element, one of the two leg portions has an intermediate portion protruding further outward in the axial direction than the opposite end portion of the one leg portion. It may be curved to do.

  Further, at the top of the substantially V-shaped corrugated element, the two legs may be connected to form a tip.

  Moreover, in the top part of the substantially V-shaped corrugated element, the other leg part of the two leg parts may be connected to one leg part so as to pierce in the axial direction.

  Moreover, in the top part of the substantially V-shaped corrugated element, the two legs may be connected so as to form a round shape.

  Further, in the wavy line pattern body, the one leg portion and the other leg portion may be alternately arranged.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress the deformation amount of the stent with respect to torsional load in the radial direction, a highly flexible stent that can improve the bendability of the stent can be provided.

It is a perspective view of the highly flexible stent of 1st Embodiment of this invention of an unloaded state. It is an expanded view which unfolds and shows the highly flexible stent of 1st Embodiment of this invention virtually expand | deployed on a plane. FIG. 3 is a partially enlarged view of the stent shown in FIG. 2. It is the elements on larger scale of the stent shown in FIG. It is the elements on larger scale of the stent shown in FIG. It is the elements on larger scale of the stent shown in FIG. It is a perspective view which shows the state which the stent of 1st Embodiment bent. It is an expanded view which expands and shows the state which overlaps and uses the stent of 1st Embodiment on a plane (corresponding figure of FIG. 2). FIG. 6 is a development view (corresponding to FIG. 5) showing a highly flexible stent according to a second embodiment of the present invention virtually developed on a plane. It is an expanded view which shows the various modifications of a coil-shaped element. It is a figure (corresponding figure of Drawing 6) showing the modification of the shape of the connection part of a coil-shaped element and the top of an annular body. It is an expanded view (corresponding figure of Drawing 2) showing the 1-1st modification which made thickness of some coil-like elements thin. It is an expanded view (corresponding figure of Drawing 2) showing the 1-2nd modification which made thickness of some coil-like elements thin. FIG. 10 is a development view (corresponding to FIG. 2) showing a first to third modified examples in which the thickness of some coil-like elements is reduced. It is an expanded view (corresponding figure of Drawing 2) showing the 1-4th modification which made thickness of some coil-like elements thin. FIG. 10 is a development view (corresponding to FIG. 2) showing a 2-1 modified example in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG. 9. FIG. 10 is a development view (corresponding to FIG. 2) showing a 2-2nd modified example in which the thickness of a part of the coil-like elements is reduced according to the second embodiment shown in FIG. 9. FIG. 10 is a development view (corresponding to FIG. 2) showing a second to third modified example in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG. 9. FIG. 10 is a development view (corresponding to FIG. 2) showing a 2-4th modification in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG. 9.

  Hereinafter, a first embodiment of a highly flexible stent according to the present invention will be described with reference to the drawings. First, the overall configuration of the highly flexible stent 11 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a highly flexible stent according to the first embodiment of the present invention in an unloaded state. FIG. 2 is a development view in which the highly flexible stent according to the first embodiment of the present invention in an unloaded state is virtually developed on a plane. FIG. 3 is a partially enlarged view of the stent shown in FIG. FIG. 4 is a partially enlarged view of the stent shown in FIG. FIG. 5 is a partially enlarged view of the stent shown in FIG. FIG. 6 is a partially enlarged view of the stent shown in FIG.

  As shown in FIG. 1, the stent 11 has a substantially cylindrical shape. The peripheral wall of the stent 11 has a mesh pattern structure in which a plurality of closed cells having congruent shapes surrounded by a wire-like material are spread in the circumferential direction. In FIG. 2, in order to facilitate understanding of the structure of the stent 11, the stent 11 is shown in a state of being deployed in a plane. Further, in FIG. 2, in order to show the periodicity of the mesh pattern, the mesh pattern is virtually repeated in a form that is more repeated than the actual developed state. In this specification, the peripheral wall of the stent 11 means a portion that separates the inside and the outside of the substantially cylindrical cylinder of the stent 11. The cell is also referred to as an opening or a compartment, and refers to a portion surrounded by a wire-like material that forms the mesh pattern of the stent 11.

  The stent 11 is made of stainless steel or a biocompatible material such as tantalum, platinum, gold, cobalt, titanium or alloys thereof.

  The stent 11 has a plurality of annular bodies 13 as a plurality of wavy pattern bodies arranged side by side in the axial direction (that is, the central axial direction) LD, and a plurality of annular bodies 13 arranged in the axial direction LD. A coiled element 15. As shown in FIG. 3, the annular body 13 has a wavy line pattern formed by connecting a plurality of substantially V-shaped wave elements 17 in which two leg portions 17 a are connected by a top portion 17 b in the circumferential direction.

  Specifically, the substantially V-shaped waveform element 17 is connected in a state where the top portion 17b is directed in the same direction in the axial direction LD. As shown in FIG.4 and FIG.5, in the two leg parts 17a adjacent to the circumferential direction, edge part 171c, 172c on the opposite side to the top part 17b is connected, and forms another top part. .

  When viewed in the radial direction RD perpendicular to the axial direction LD, the ring direction CD of the annular body 13 is inclined with respect to the radial direction RD. An angle θ3 at which the ring direction CD of the annular body 13 is inclined with respect to the radial direction RD is, for example, 30 degrees to 60 degrees.

  Note that the radial direction RD is a direction perpendicular to the axial direction LD, and therefore there are countless numbers. 3, 4, 5, etc., the radial direction RD in “when viewed in the radial direction RD” is a direction that penetrates the paper surface of FIG. 3, FIG. 4, FIG. 5, etc. The radial direction RD in “inclined relative to” is a direction along the paper surface of FIG. 3, FIG. 4, FIG.

  The present applicant has filed a patent application: Japanese Patent Application No. 2014-165104 regarding the basic contents of the present invention. The contents described in Japanese Patent Application No. 2014-165104 can be appropriately applied or incorporated in the present invention.

  Both end portions of each coil-like element 15 are connected to the opposite top portions 17b of the two adjacent annular bodies 13, respectively. Note that all of the opposing top portions 17b of the adjacent annular bodies 13 are connected to each other by the coil-like elements 15. The stent 11 has a so-called closed cell structure. That is, two apexes 17b located adjacent to each other along the wavy line pattern among the three apexes 17b connected to each other by the legs 17a along the wavy pattern on one of the adjacent annular bodies 13 are respectively coiled. The element 15 is connected to two apexes located next to each other along the wavy line pattern among the three apexes connected to each other by the legs 17a along the wavy pattern on the other of the adjacent annular bodies 13, A cell is formed. And all the top parts 17b of the wavy pattern of each annular body 13 are shared by three cells.

  The plurality of coil-like elements 15 are arranged at equal intervals along the ring direction CD of the annular body 13. Each coil-like element 15 extends spirally around the central axis. As shown in FIG. 3, the winding direction (right winding) of one coil-like element 15 (15R) located on one side in the axial direction LD with respect to the annular body 13 and the other located on the other side of the axial direction LD. The coiling element 15 (15L) is wound in the opposite direction (left-handed). The length of one coiled element 15R is shorter than the length of the other coiled element 15L.

  As shown in FIG. 6, a ridge 19 is formed at the top 17 b of the wave element 17. The knob portion 19 includes an extension portion 19a that extends linearly in the axial direction LD, and a substantially semicircular portion (tip portion) 19b formed at the tip thereof. The extension portion 19 a has a width that is greater than the width of the coiled element 15. Furthermore, a slit 21 extending in the axial direction LD from the inner peripheral edge is formed in the top 17b of the wave element 17. For this reason, the two leg portions 17a are connected to a region where the slit 21 is not provided in the extended portion 19a and a substantially semicircular portion 19b of the knob-like portion 19 through a linear portion extending substantially parallel to the axial direction LD. Is done. In addition, although it is preferable that the front-end | tip part 19b is a substantially semicircle substantially semicircle part, it does not need to be a substantially semicircle (not shown).

  A curved portion 15 a is formed at both ends of each coil-like element 15. Both end portions of each coil-shaped element 15 are connected to the top portions 17b (specifically, the knob-shaped portions 19) of the two adjacent annular bodies 13 on the opposite sides via the curved portions 15a. As shown in FIG. 6, the curved portions 15 a at both ends of the coiled element 15 have an arc shape. The tangential direction of the coiled element 15 at the connection end between the coiled element 15 and the top 17b of the wavy pattern of the annular body 13 coincides with the axial direction LD.

  The center in the width direction of the end of the coil-shaped element 15 and the apex (the center in the width direction) of the top portion 17b of the annular body 13 are shifted (not coincident). One end edge in the width direction of the end portion of the coil-shaped element 15 and the end edge in the width direction of the top portion 17 b of the annular body 13 coincide with each other.

  By providing the stent 11 with the above-described structure, the stent 11 realizes excellent shape followability and diameter reduction, and is less likely to cause damage to the stent due to metal fatigue. The ridge 19 provided on the top 17b of the corrugated element 17 of the annular body 13 of the stent 11 has an effect of reducing metal fatigue. The slit 21 extending from the inner peripheral edge of the top portion 17 b of the corrugated element 17 of the annular body 13 of the stent 11 has an effect of improving the diameter reduction property of the stent 11.

  A conventional closed-cell stent is structurally lacking in flexibility, and thus has a risk of causing buckling in a bent blood vessel and causing blood flow inhibition. When the stent is locally deformed, the influence of the deformation is propagated not only in the radial direction RD of the stent but also in the axial direction LD, and the stent cannot be locally deformed independently. As a result, the stent cannot be adapted to a complicated vascular structure such as an aneurysm, and a gap is formed between the peripheral wall of the stent and the vascular wall. There is also a risk that the stent may become slippery in the lumen and may cause migration (migration) of the stent after placement.

  On the other hand, when the stent 11 of the present embodiment is deformed from the expanded (expanded) state to the reduced diameter (crimped) state, the stent 11 is compressed so that the wavy pattern of the annular body 13 is folded, and the coil 11 The state-like element 15 is in a state of being pulled in the axial direction LD while lying in the axial direction LD like a coil spring. Considering one of the corrugated elements 17 in the wavy pattern of the annular body 13 of the stent 11, the corrugated element 17 is deformed like opening and closing of tweezers when the diameter of the stent 11 is reduced and expanded.

  If the slit 21 is not provided in the root valley side portion (the inner peripheral edge of the top portion 17b) of the corrugated element 17, when the corrugated element 17 is deformed so as to be closed when the diameter of the stent 11 is reduced, the leg portion 17a The central part bulges outward in a barrel shape and easily deforms. When the corrugated element 17 expands and deforms in a barrel shape in this way, when the diameter of the stent 11 is reduced, the portions of the annular body 13 that are swollen in the barrel shape of the leg portions 17a of the corrugated elements 17 adjacent in the circumferential direction are Contact.

  This contact prevents the stent 11 (especially the annular body 13) from being reduced in diameter, and causes a reduction in the diameter reduction rate. On the other hand, in the stent 11 of the present embodiment, a slit 21 is provided at the root portion of the corrugated element 17 of the annular body 13. Therefore, when the diameter of the stent 11 is reduced, the stent 11 is deformed, and the leg portions 17a of the wave elements 17 adjacent to each other in the circumferential direction in the annular body 13 are difficult to contact with each other, and the diameter reduction rate can be increased. .

  When the slit 21 is provided in the top portion 17 b of the corrugated element 17 of the annular body 13 of the stent 11, the length of the extended portion 19 a of the knob-like portion 19 provided in the top portion 17 b has a length exceeding the slit 21. By constituting in this way, the volume ratio which transforms into a martensite phase in the peripheral part of slit 21 at the time of load increases. Therefore, by configuring the stent 11 to include the corrugated element 17 having the apex portion 17b, the stent 11 is provided with a change in expansion force with respect to a change in the diameter of the stent 11 and a small change in expansion force even with different blood vessel diameters. Can be realized.

  The curved portions 15a provided at both ends of the coiled element 15 of the stent 11 have the effect of further smoothing the deformation of the coiled element 15 at the connecting portion with the annular body 13 and increasing the diameter reduction property of the stent 11. .

  When the diameter of the stent 11 is reduced, the coiled element 15 is deformed so as to be stretched in the axial direction LD. Therefore, in order to increase the flexibility of the stent 11, it is necessary to design the connection portion between the top portion 17 b of the annular body 13 and the coiled element 15 to be flexible. In the stent 11, a curved portion 15 a having an arc shape is provided at both ends of the coiled element 15, and the top portion 17 b of the annular body 13 and the coiled element 15 are connected via the curved portion 15 a. When the diameter of the stent 11 is reduced, the bending portion 15a is bent and deformed, whereby the coiled element 15 can be flexibly deformed and the diameter reduction property is improved.

  In addition, the configuration in which the tangential direction of the curved portion 15a at the connection end where the coiled element 15 and the top portion 17b of the annular body 13 are connected coincides with the axial direction LD facilitates deformation due to the diameter reduction and expansion of the stent 11. At the same time, the effect of moderating the change in the expansion force with respect to the change in the diameter of the stent 11 is achieved.

  The coil-like element 15 is deformed like a coil spring and extends in the axial direction LD, thereby enabling deformation in the radial direction RD accompanying the diameter reduction of the stent 11. Therefore, by making the tangential direction of the curved portion 15a at the connection end where the annular body 13 and the coil-shaped element 15 connect coincide with the axial direction LD, the deformation characteristics of the coil-shaped element 15 in the axial direction LD are effectively exhibited. become able to. As a result of the coil-shaped element 15 being able to be smoothly deformed in the axial direction LD, the diameter reduction and expansion of the stent 11 are facilitated. In addition, the natural deformation of the coiled element 15 in the axial direction LD can be promoted, so that an unexpected deformation resistance can be prevented, and the response of the expansion force to the change in the diameter of the stent 11 becomes gentle. Play.

  The stent 11 is inserted into the catheter in a contracted state, is pushed by an extruder such as a pusher, moves through the catheter, and is deployed at a lesion site. At this time, the force in the axial direction LD applied by the extruder is transmitted to the entire stent 11 while interacting between the annular body 13 and the coiled element 15 of the stent 11.

  The stent 11 having the above-described structure is produced, for example, by laser processing a biocompatible material, particularly preferably a tube formed of a superelastic alloy. When producing from a super elastic alloy tube, in order to reduce the cost, the tube of about 2 to 3 mm is expanded to a desired diameter after laser processing, and the stent 11 is produced by applying shape memory processing to the tube. It is preferable. However, the production of the stent 11 is not limited to laser machining, and can be produced by other methods such as cutting.

  Next, features of the present invention will be described in detail. As shown in FIGS. 4 and 5, the top portion 17b of the substantially V-shaped corrugated element 17 has end portions 171c, 171c, opposite to the top portions 17b of the two leg portions 17a (171, 172) in the axial direction LD. It is located between 172c (another top). In FIG. 4 and FIG. 5, for the convenience of understanding these positional relationships, a one-dot chain line parallel to the radial direction RD is drawn from one end 171 c on one side, the top 17 b and the other end 172 c on the other side. ing.

  In the substantially V-shaped corrugated element 17, one leg portion 171 of the two leg portions 17 a has an intermediate portion 171 d outside the opposite end portion 171 c of the one leg portion 171 in the axial direction LD. It is curved so as to protrude to the right (in FIG. 4 and FIG. 5). That is, in the axial direction LD, the intermediate portion 171d, the opposite end portion 171c, and the top portion 17b are arranged in this order. The direction in which the intermediate portion 171d of one leg 171 protrudes may be the direction in which the stent is pushed out from the catheter, or the direction in which the stent is pulled back (recovery direction). is there.

In the top part 17b of the substantially V-shaped corrugated element 17, the two leg parts 17a (171, 172) are connected so as to form a pointed end. The other leg 172 is connected so as to pierce the one leg 171. Specifically, the other leg 172 is connected to the one leg 171 so as to pierce in the axial direction LD. The other leg portion 172 extends substantially linearly except for the vicinity of both end portions thereof.
In the annular body 13, one leg 171 and the other leg 172 are alternately arranged.

  Next, a description will be given of the operational effect of the configuration “when viewed in the radial direction RD perpendicular to the axial direction LD, the ring direction CD of the annular body 13 is inclined with respect to the radial direction RD”. First, a stent having a structure in which the ring direction CD of the annular body 13 is along the radial direction RD when viewed in the radial direction RD (not inclined with respect to the radial direction RD) will be described.

In a stent having a structure in which the ring direction CD of the annular body 13 is not inclined with respect to the radial direction RD, the central axis of the cross section of the stent is likely to be shifted in a strong blood vessel in the skull.
On the other hand, in the stent 11 of the present embodiment, the annular body 13 having a wavy pattern can be easily deformed in the circumferential direction, so that the stent 11 can flexibly cope with contraction and expansion in the radial direction RD. . Moreover, the coil-shaped element 15 which connects the adjacent annular bodies 13 and 13 extends spirally around the central axis, and is deformed like a coil spring. Therefore, when the stent 11 is bent, the coiled element 15 extends outside the bent part, and the coiled element 15 contracts inside the bent part. Accordingly, the entire stent 11 can be flexibly deformed in the axial direction LD.

  Further, the external force or deformation locally applied to the stent 11 is transmitted in the radial direction RD by the wavy line-shaped annular body 13 and also transmitted in the circumferential direction by the coiled element 15. Therefore, the annular body 13 and the coiled element 15 can be deformed almost independently at each portion. Thereby, even when the stent 11 is applied to a lesion site of a special blood vessel such as a cerebral aneurysm, the stent 11 can be placed in conformity with the blood vessel structure of the lesion site. For example, when the stent 11 is placed at the site of a cerebral aneurysm, the annular body 13 having a wavy pattern is disposed at the neck portion of the aneurysm. Thereby, the annular body 13 expands in the radial direction RD and protrudes into the space of the aneurysm, and the stent 11 can be stably fixed to this portion.

  Furthermore, the coiled element 15 contacts the blood vessel wall around the neck portion of the aneurysm along the shape of the blood vessel wall, and acts as an anchor. Therefore, the risk that the stent 11 moves is also reduced. Furthermore, since the stent 11 has a closed cell structure, even when applied to a bending site, the strut of the stent 11 protrudes outward in a flared shape to damage the blood vessel wall, or the strut of the stent 11 is blood. The risk of causing alienation can be reduced.

  Further, when the stent 11 is twisted counterclockwise, a force acts so that one of the coil-like elements 15 is pulled in a direction perpendicular to the wire cross section of the spring. Therefore, the strands are deformed so as to be wound in the circumferential direction, and exhibit a behavior of reducing the diameter in the radial direction RD. However, the other coil-like element 15 exerts a force so as to be compressed in the direction perpendicular to the wire cross section of the spring. Therefore, the element wire is deformed so as to be separated in the circumferential direction, and as a result, the outer diameter expands in the radial direction RD. As a result, the deformation of one coil-like element 15 and the other coil-like element 15 in each unit cancel each other, so that the deformation amount in the radial direction RD of the coil-like element 15 in the entire stent 11 is suppressed.

On the other hand, when the stent 11 is twisted clockwise, a force acts so that the other coil-like element 15 is pulled in a direction perpendicular to the strand cross section of the spring. Therefore, the strands are deformed so as to be wound in the circumferential direction, and exhibit a behavior of reducing the diameter in the radial direction RD. However, a force acts so that one coil-shaped element 15 is compressed in the perpendicular direction with respect to the wire cross section of the spring. Therefore, the element wire is deformed so as to be separated in the circumferential direction, and as a result, the outer diameter expands in the radial direction RD. As a result, the deformation of one coiled element 15 and the deformation of the other coiled element 15 cancel each other, so that the deformation amount in the radial direction RD of the coiled element 15 in the entire stent 11 is suppressed.
Thus, by introducing the coil-like elements 15R and 15L whose winding directions are opposite to each other, the difference in deformation amount in the radial direction RD can be reduced with respect to the left and right twist deformation.

  The material of the stent is preferably a material having high rigidity and high biocompatibility. 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 alloys containing these. It is done. Moreover, as such a material, synthetic resin materials such as polyolefin such as PE and PP, polyamide, polyvinyl chloride, polyphenylene sulfide, polycarbonate, polyether, and polymethyl methacrylate can be used. Furthermore, as such a material, biodegradable resins (biodegradable polymers) such as polylactic acid (PLA), polyhydroxybutyrate (PHB), polyglycolic acid (PGA), and poly-ε-caprolactone can also be used. .

  The stent may contain a drug. Here, that the stent contains the drug means that the stent releasably carries the drug so that the drug can be eluted. The drug is not limited, and for example, a physiologically active substance can be used.

  In order to include the drug in the stent, for example, the surface of the stent may be coated with the drug. At this time, the surface of the stent may be directly coated with the drug, or the drug may be included in a polymer, and the stent may be coated with the polymer. Further, a groove or a hole for storing the drug in the stent may be provided as a reservoir, and the drug or a mixture of the drug and the polymer may be stored therein. The reservoir for storing is described in, for example, JP-T 2009-524501.

  A diamond-like carbon (DLC layer) layer (DLC layer) can be coated on the surface of the stent. The DLC layer may be a DLC layer containing fluorine (F-DLC layer). In that case, the stent is excellent in antithrombogenicity and biocompatibility.

  Next, a method for using the stent 11 will be described. A catheter is inserted into the patient's blood vessel and allowed to reach the lesion site. Next, the stent 11 is reduced in diameter (crimped) and placed in the catheter. In the stent 11, the wavy pattern of the annular body 13, the slit 21 formed in the top portion 17 b of the annular body 13, the curved portion 15 a of the coiled element 15, and the tangential direction of the curved portion 15 a at the connection end coincide with the axial direction LD. Due to the combined and synergistic effects of the configuration, the diameter reduction is enhanced. Therefore, it becomes easy to insert the stent 11 into a thinner catheter as compared with the conventional stent, and the stent 11 can be applied to a thinner blood vessel.

  Next, the stent having a reduced diameter is pushed along the lumen of the catheter using an extruder such as a pusher, and the stent 11 is pushed out from the distal end of the catheter at the lesion site to be deployed. The stent 11 is a composite and synergistic structure in which a plurality of annular bodies 13 are connected by a coil-shaped element 15, a curved portion 15a of the coil-shaped element 15, and a tangential direction of the curved portion 15a at the connection end coincides with the axial direction LD. As a result, the stent 11 can be flexibly deformed along the catheter even when the catheter is inserted into a meandering blood vessel, and the stent 11 can be moved to the lesion site. Easy to transport.

According to the stent 11 of 1st Embodiment, the following effects are show | played, for example.
In the first embodiment, the annular body 13 is formed by connecting a plurality of substantially V-shaped waveform elements 17 in which two leg portions 17a (171, 172) are connected by a top portion 17b in the circumferential direction, The top portion 17b of the substantially V-shaped corrugated element 17 is located between the end portions 171c and 172c opposite to the top portion 17b in the two leg portions 17a in the axial direction LD.

  Therefore, according to the stent 11 of the first embodiment, the top portion 17b of the substantially V-shaped corrugated element 17 has the end portions 171c and 172c opposite to the top portion 17b in the two leg portions 17a in the axial direction LD. Compared with the case where it is not located between the two, as shown in FIG. 7, it is easy to bend flexibly in the axial direction LD, and the flexibility can be improved.

  In the stent 11 of the first embodiment, in the substantially V-shaped corrugated element 17, one leg 171 of the two legs 17 a has an intermediate part 171 d on the opposite side of the one leg 171. It curves so that it may protrude to the outer side of axial direction LD rather than the edge part 171c. Therefore, compared with the case where the intermediate portion 171d of one leg 171 is not curved, the width (length) in the radial direction RD of the substantially V-shaped corrugated element 17 can be shortened, and the bending of the stent The property can be further improved.

  Moreover, in the stent 11 of 1st Embodiment, the other leg part 172 is connected with the one leg part 171 so that it may stab in the axial direction LD in the top part 17b of the substantially V-shaped waveform element 17. FIG. Therefore, compared with the case where the other leg 172 is connected to the one leg 171 so as to pierce in the radial direction RD, the resistance when the stent is pulled back (recovered) into the catheter can be reduced.

  In the peripheral wall of the stent 11 of the present embodiment, the ratio of the existing area of the mesh pattern (the annular body 13 and the coiled element 15) to the virtual area of the peripheral wall (the area when it is assumed that there is no mesh pattern opening) ( The density of the surface density is clearly separated. Specifically, as shown in FIG. 1, in the axial direction LD, small openings 12a and large openings 12b having an area that is, for example, four times larger than the small openings 12a are alternately arranged. Therefore, the flexibility of the stent is high. On the other hand, when the density of the surface density is clear, a problem may occur.

  Therefore, as shown in FIG. 8, the two stents 11 may be used by being overlapped by being shifted by a half pitch in the circumferential direction. In this case, the density of the surface density can be made nearly uniform, and problems caused by the clear density of the surface density can be suppressed, and high flexibility (flexibility) can be obtained. .

  In addition, the number to overlap is not limited to double, and may be triple or more. The shifting pitch may be other than a half pitch. Stents of the same shape may be stacked. Also, different shaped stents may be stacked. In that case, two stents in which the ring direction CD of the annular body 13 with respect to the radial direction RD is opposite to each other may be overlapped.

The double-stacked stent can be applied to, for example, a portion where the blood vessel is divided into two branches (Y shape). A small diameter stent is placed inside a large diameter stent. A large-diameter stent is placed over one Y-shaped blood vessel. The small diameter stent is pushed out toward the other Y-shaped blood vessel through the large opening of the mesh pattern in the large diameter stent.
In addition, although the stent of this embodiment can be used as both an indwelling type and a collection type stent, it is preferable to use the stent as an indwelling type.

  The stent 11 can suppress the occurrence of metal fatigue due to the configuration in which the ridge portion 19 is provided on the top portion 17b of the annular body 13, and the stent 11 is repeatedly reduced in diameter and expanded due to an indwelling error. Breakage of the stent 11 due to repeated deformation of the stent 11 due to pulsation can be suppressed.

  In addition, the stent 11 has a structure in which a slit 21 is provided in the top portion 17b of the annular body 13 to increase a region that transforms into a martensite phase in the deformed portion at the time of crimping, a curved portion 15a of the coiled element 15, and a connection end. As a result of the combined and synergistic effect with the configuration in which the tangential direction of the curved portion 15a coincides with the axial direction LD, the flexibility is improved, and the change in the expansion force with respect to the change in the diameter of the stent 11 during the unloading process is moderate. become. As a result, the shape followability of the stent 11 is improved, and the stent 11 can be placed without applying an excessive load to the blood vessel even in a region where the blood vessel diameter locally changes such as a tapered blood vessel. It becomes possible.

  Next, another embodiment of the stent of the present invention will be described. For the points that are not particularly described in the other embodiments, the description of the first embodiment is incorporated as appropriate. Also in other embodiment, there exists an effect similar to 1st Embodiment. FIG. 9 is a developed view (corresponding to FIG. 5) showing the highly flexible stent of the second embodiment of the present invention virtually developed on a plane.

  As shown in FIG. 9, in the stent 11A of the second embodiment, two legs 17a (171, 172) are connected so as to form a round shape at the top portion 17b of the substantially V-shaped corrugated element 17. ing. The other leg 172 is connected to the one leg 171 so as to pierce in the radial direction RD. Other configurations are the same as those of the first embodiment.

  In the above-described embodiment, the wavy pattern body 13 forms an annular body. On the other hand, in the present invention, a wavy pattern body 13 that is discontinuous in the circumferential direction and does not form an annular body can be employed. The wavy line pattern body 13 that does not form an annular body has a shape in which one or more struts (leg portions 17a) that constitute the wavy line pattern body are removed, compared to the wavy line pattern body that forms an annular body. The number of struts to be pulled out can be appropriately set to one or more within the range in which the shape of the stent 11 can be realized.

  Further, an additional strut extending in the ring direction CD can be provided so as to connect the coiled elements 15 adjacent in the ring direction CD. In addition, the shape of the additional strut, the position where it is provided, the number, etc. are not particularly limited.

  When attention is paid to one coiled element 15R, one adjacent coiled element 15R can be deformed, and the other adjacent coiled element 15L can be deformed.

FIG. 10 is a development view showing various modifications of the coiled element 15. As shown in FIG. 10, the degree of bending (curvature) of the coiled element 15-1 is larger than that of the coiled element 15 shown in FIG. The degree of bending (curvature) of the coiled element 15-2 is larger than that of the coiled element 15-1. The coil-shaped element 15-3 has a curved shape that protrudes in a direction orthogonal to the ring direction CD. The coiled element 15-4 has a curved shape having four inflection points.
In addition, in FIG. 10, the top part 17b of the substantially V-shaped waveform element 17 is not located between the ends of the two leg parts 17a opposite to the top parts 17b in the axial direction LD.

  Various modifications relating to the shape of the coil-shaped element 15 shown in FIG. 10 can be applied or used as appropriate to modifications related to the shape of the leg portion 17a of the wave element 17.

  FIG. 11 is a diagram (corresponding to FIG. 6) showing a modification of the shape of the connection portion between the coil-shaped element 15 and the top portion 17 b of the annular body 13. As shown in FIG. 11, the center in the width direction of the end of the coil-shaped element 15 and the apex (the center in the width direction) of the top portion 17 b of the annular body 13 coincide with each other. One edge in the width direction of the end portion of the coil-shaped element 15 and the edge in the width direction of the top portion 17b of the annular body 13 are shifted (not coincident).

  Some coil-like elements 15 can be made thinner than the other coil-like elements 15 and the annular body 13 (waveform element 17). FIG. 12 is a development view (corresponding to FIG. 2) showing a first-first modification example in which the thickness of some coil-like elements is reduced. FIG. 13 is a developed view (corresponding to FIG. 2) showing a first-second modification in which the thickness of some coil-like elements is reduced. FIG. 14 is a development view (corresponding to FIG. 2) showing a first to third modified examples in which some coil-like elements are made thinner. FIG. 15 is a developed view (corresponding to FIG. 2) showing a first to fourth modified examples in which the thickness of some coil-like elements is reduced.

As shown in FIG. 12, in the first-first modification, all the other (left-handed) coil-like elements 15 (15L) are thinner than the example shown in FIG. The coil-shaped element 15 (15R) and the annular body 13 are configured not to be thin.
As shown in FIG. 13, the first-second modification is different from the first-first modification shown in FIG. 12 in the other (left-handed) coiled element 15 (15L) every other row in the axial direction LD. However, the other coil-like elements 15 and the annular body 13 are not thin.

As illustrated in FIG. 14, the first to third modified examples are configured such that the position of the thin coil-shaped element 15 </ b> L is shifted in the axial direction LD as compared to the first to second modified example illustrated in FIG. 13.
As shown in FIG. 15, the first to fourth modified examples are compared with the first to first modified examples shown in FIG. 12, and the other (left-handed) coiled element 15 (15 </ b> L) located at both ends in the axial direction LD. Is not thin, and the other (left-handed) coiled element 15 (15L) is thin.

The stent 11 maintains the rigidity in the radial direction RD by forming a part of the coiled elements 15 to be thin as in the first to first to first to fourth modifications shown in FIGS. As it is, the bending rigidity can be increased (the bending flexibility can be increased).
In addition, in the above-mentioned 1-1st modification-1-4th modification, although the example which made the other (left-handed) coil-shaped element 15 (15L) thin was demonstrated, it is not restrict | limited to this. One (right-handed) coiled element 15 (15R) can also be made thin. Also in this case, the same effect as that obtained when the other (left-handed) coiled element 15 (15L) is thinned can be obtained.

  Also in the second embodiment shown in FIG. 9, a part of the coil-like elements 15 are replaced in the same manner as the first to first to first to fourth modifications according to the first embodiment shown in FIGS. 12 to 15. It can be made thinner than the other coil-shaped elements 15 and the annular body 13 (waveform element 17). FIG. 16 is a development view (corresponding to FIG. 2) showing a 2-1 modified example in which the thickness of a part of the coil-like elements is reduced according to the second embodiment shown in FIG. 9. FIG. 17 is a development view (corresponding to FIG. 2) showing a 2-2nd modified example in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG. 9. FIG. 18 is a developed view (corresponding to FIG. 2) showing a second to third modified example in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG. FIG. 19 is a developed view (corresponding to FIG. 2) showing a second to fourth modified example in which the thickness of some coil-like elements is reduced according to the second embodiment shown in FIG.

As shown in FIG. 16, in the 2-1 modification, all the other (left-handed) coiled elements 15 (15L) are thinner than the example shown in FIG. The coil-shaped element 15 (15R) and the annular body 13 are configured not to be thin.
As shown in FIG. 17, the 2-2 modification is the other (left-handed) coiled element 15 (15L) in every other row in the axial direction LD direction as compared to the 2-1 modification shown in FIG. 16. However, the other coil-like elements 15 and the annular body 13 are not thin.

As illustrated in FIG. 18, the second to third modified examples are configured such that the position of the thin coil-shaped element 15 </ b> L is shifted in the axial direction LD as compared with the second to second modified example illustrated in FIG. 17.
As shown in FIG. 19, the second to fourth modifications are the other (left-handed) coiled elements 15 (15 </ b> L) located at both ends in the axial direction LD as compared to the 2-1 modification shown in FIG. 16. Is not thin, and the other (left-handed) coiled element 15 (15L) is thin.

As shown in FIGS. 16 to 19, some of the coil-like elements 15 are configured to be thin as in the 2-1 to 2-4 modifications, so that the stent 11 maintains the rigidity in the radial direction RD. As it is, the bending rigidity can be increased (the bending flexibility can be increased).
In addition, in the above-described 2-1 modified example to 2-4 modified example, the example in which the other (left-handed) coiled element 15 (15L) is thinned has been described, but the present invention is not limited to this. One (right-handed) coiled element 15 (15R) can also be made thin. Also in this case, the same effect as that obtained when the other (left-handed) coiled element 15 (15L) is thinned can be obtained.

Although the stent according to the present invention has been described above with reference to the illustrated embodiment, the present invention is not limited to the illustrated embodiment. For example, the spiral direction of the coiled element 15 may be left-handed or right-handed.
The stent of the present invention can be applied to cerebral blood vessels, lower limb blood vessels, and other blood vessels.

11, 11A stent (highly flexible stent)
13 Ring body (wavy line pattern body)
15 coiled element 15L other coiled element 15R one coiled element 17 corrugated element 17a leg 171 one leg 171c opposite end 171d intermediate 172 other leg 172c opposite end 17b top CD Ring direction LD Axial direction RD Radial direction

Claims (6)

A plurality of wavy pattern bodies having a wavy pattern and arranged side by side in the axial direction, and a plurality of coil-like elements arranged between adjacent wavy pattern bodies and extending spirally around the axis. A highly flexible stent in which the tops on opposite sides of the wavy line pattern of adjacent wavy line pattern bodies are connected to each other by the coiled elements,
When viewed in the radial direction perpendicular to the axial direction, the ring direction of the wavy pattern body is inclined with respect to the radial direction,
The wavy pattern body is formed by connecting a plurality of substantially V-shaped corrugated elements having two legs connected at the top in the circumferential direction,
The apex of the substantially V-shaped corrugated element is located between the ends of the two legs opposite to the apex in the axial direction,
The winding direction of one of the coiled elements located on one side in the axial direction with respect to the wavy pattern body is opposite to the winding direction of the other coiled element located on the other side in the axial direction. Suppressed the amount of deformation in the stent radial direction against torsional load,
High flexibility stent. In the substantially V-shaped corrugated element, one of the two leg portions has an intermediate portion protruding outward in the axial direction from the opposite end portion of the one leg portion. Is curved,
The highly flexible stent according to claim 1. At the top of the substantially V-shaped corrugated element, the two legs are connected to form a point,
The highly flexible stent according to claim 1 or 2. At the top of the substantially V-shaped corrugated element, the other leg of the two legs is connected to one leg so as to pierce in the axial direction.
The highly flexible stent according to claim 3. At the top of the substantially V-shaped corrugated element, the two legs are connected to form a roundness,
The highly flexible stent according to claim 1 or 2. In the wavy pattern body, one leg and the other leg are alternately arranged.
The highly flexible stent according to any one of claims 1 to 5.