JP7490922B2 - Stents - Google Patents

Description

The present invention relates to a stent.

Conventionally, stents are known that are placed in narrowed or blocked areas in biological lumens, such as blood vessels, the esophagus, the small intestine, the large intestine, the bile duct, the trachea, and the ureter, to expand the diameter of the diseased area and maintain the patency of the biological lumen (see, for example, Patent Document 1).

Patent No. 4651943

Incidentally, a partially covered stent in which a part of the framework is exposed from the coating is useful for preventing the exudation of cell tissue and suppressing displacement from the placement site.
However, since the skeletal portion is formed from laser cutting, a woven structure, a spiral structure, or the like, taking into consideration, for example, the resistance to displacement from the placement site, the ability to follow changes in the shape of the biological lumen, and the ability to retain its shape, it is not sufficient to simply expose a portion of the skeletal portion of the fully covered stent from the coating portion to form a bare portion.
Furthermore, if the bare portion and the covered portion are connected to each other with different skeletal structures, they may be separated by peristaltic movements in the body, and the stent may become dislodged from the placement site.

The object of the present invention is to provide a stent that is unlikely to shift from its placement site in the biological lumen and that is highly adaptable to changes in the shape of the biological lumen.

The stent according to the present invention comprises:
A stent to be placed in a biological lumen,
A cylindrical skeleton portion formed of a wire rod and expandable and contractable in a radial direction substantially perpendicular to an axial direction;
a coating portion disposed along a circumferential surface of a first skeletal portion of the skeletal portion,
The second skeletal portion in which the coating portion is not arranged is made of at least one of the wires forming the first skeletal portion , and has a braided structure in which the wire pulled out from the tip portion of the first skeletal portion wraps around the periphery of the tip portion of the first skeletal portion while forming a waveform so that the peaks and valleys of each turn do not overlap, and is configured to be expandable and contractible in the axial direction.

The present invention provides a stent that is less likely to shift from its placement site in the biological lumen and has good conformity to changes in shape in the biological lumen.

1A and 1B are diagrams showing a configuration of a stent placement system according to an embodiment. FIG. 2 is an external perspective view showing the configuration of a colonic stent according to an embodiment. 3A to 3C are schematic diagrams showing changes in state during placement of a colonic stent.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In this embodiment, as an example of the present invention, a colonic stent 1 is described which is placed in the large intestine C to treat the obstruction (stenosis) by expanding a lesion L of the large intestine C (e.g., an obstructed or narrowed portion of the large intestine C, see Figure 3) radially outward.

Figures 1A and 1B are diagrams showing the configuration of the stent placement system 100. Figure 1A shows the stent placement system 100 in a disassembled state, and Figure 1B shows the stent placement system 100 in an assembled state. Note that in Figures 1A and 1B, the size (length, diameter, etc.) and shape of each component constituting the stent placement system 100 are shown in schematic form to facilitate understanding of the invention.

The stent placement system 100 is used, for example, by inserting it into the forceps hole of an endoscope when placing a colonic stent 1 in the colon C. As shown in Figures 1A and 1B, the stent placement system 100 includes a tubular sheath 2, an inner rod 3 disposed inside the sheath 2 and configured to be able to advance and retreat within the sheath 2 along the axial direction (longitudinal direction) of the sheath 2, and a colonic stent 1 housed within the sheath 2 in a contracted state that is able to expand radially.

The sheath 2 has, for example, a tubular sheath body 21 made of a flexible material, and a hub 22 provided on the base end side of the sheath body 21 (on the right side in Figs. 1A and 1B) for fixing and releasing the inner rod 3 to and from the sheath body 21.

The inner rod 3 has, for example, a rod-shaped rod body 31, a holding portion 32 formed with a smaller diameter than the rod body 31 and holding the colon stent 1 in a contracted state, and a tip tip 33 provided at the tip (distal end) of the inner rod 3.

Although not shown in the figure, the rod main body 31, the holding portion 32 and the tip tip 33 are formed with, for example, a guide wire lumen for passing a guide wire, a trigger wire lumen for passing a trigger wire for expanding the colon stent 1 in a contracted state at the affected area, and the like, along the axial direction of the inner rod 3.
The rod body 31, the holding portion 32 and the tip 33 are formed from various materials having appropriate hardness and flexibility, such as resin or metal, but detailed description thereof will be omitted here.

FIG. 2 is a perspective view that diagrammatically illustrates the colonic stent 1. As shown in FIG.
The colonic stent 1 has a cylindrical shape that defines a tubular flow path through which digestive matter flows. The colonic stent 1 is a partially covered stent of one-sided flare type, and is divided into a straight covered portion 1A in which a coating portion 12 is disposed, and a flared bare portion 1B in which a coating portion 12 is not disposed. The colonic stent 1 is placed at a lesion site L in the large intestine C so that one end is located upstream (mouth side) in the flow direction of digestive matter and the other end is located downstream (anus side) in the flow direction of digestive matter. In the following description, the left side (end side of bare portion 1B) in FIG. 2 is the tip side, and the right side (end side of covered portion 1A) is the rear end side.
The colonic stent 1 may have a removal aid portion for hooking a removal wire on the end portion that is pulled into a recovery tube or the like during removal.

As shown in FIG. 2, the colonic stent 1 has a skeleton portion 11 and a coating portion 12. The colonic stent 1 has an elongation restricting portion 13 along the axial direction.

The skeletal portion 11 functions as a reinforcing member that holds the coating portion 12 in a predetermined expanded state. The skeletal portion 11 also memorizes the shape of the expanded state and has so-called self-expandability. In other words, the skeletal portion 11 (the first skeletal portion 111 and the second skeletal portion 112) is configured to be self-expandable in the radial direction, which is approximately perpendicular to the axial direction, from a contracted state in which it contracts inward to an expanded state in which it expands outward to define a cylindrical flow path.

The material of the metal wire forming the skeleton 11 may be, for example, a known metal or metal alloy such as stainless steel, nickel-titanium alloy (nitinol), titanium alloy, etc. An alloy material having X-ray contrast properties may also be used. In this case, the position of the colonic stent 1 can be confirmed from outside the body. The skeleton 11 may also be formed from a material other than a metal material (for example, ceramic, resin, etc.).

The skeleton 11 (particularly the first skeleton 111) is configured to be deformable in response to an external force applied from the outer surface side. As a result, even if an external force is applied to the colonic stent 1 from the outer surface side, the skeleton 11 deforms, so that the stent can continue to expand the lesion site L of the colon C while remaining at the placement site without kinking.

The material, wire type (e.g., circular wire such as wire, or angular wire processed by laser processing), wire diameter (cross-sectional area), number of folds in the circumferential direction and fold shape (number of peaks and shape of peaks), and wire spacing in the axial direction (helical pitch (amount of framework per unit length)) of the wire forming the framework 11 are appropriately selected based on the flexibility required for the digestive tract in which it is placed. Flexibility refers to the ease with which the colonic stent 1 bends, and is determined in particular by the axial bending rigidity (synonymous with straightening force). In other words, the framework 11 has a structure that can be deformed in response to an external force, and has a property that has an appropriately low axial bending rigidity and can follow the shape of the biological lumen or sheath without kinking in the biological lumen or sheath such as the digestive tract.

In this embodiment, the skeleton 11 has a first skeleton 111 having a cylindrical shape and a second skeleton 112 provided at the distal end of the first skeleton 111 and having a flared shape that expands in diameter toward the distal end. The colonic stent 1 is placed in the large intestine C so that the second skeleton 112 is located upstream in the flow direction of the digestive matter.

The first skeleton 111 is the main skeleton that occupies the majority of the skeleton 11, and is formed into a cylindrical shape overall by, for example, winding a metal wire W in a spiral shape while bending it so that peaks and valleys are formed alternately in the axial direction (a so-called Z-spiral structure). This allows the colonic stent 1 to have the flexibility described above.

The second skeletal portion 112 is an end skeleton provided at the tip side of the first skeletal portion 111, and is formed from the same metal wire W as the first skeletal portion 111. In other words, the second skeletal portion 112 is formed from a different material from the first skeletal portion 111, and is not connected by crimping or the like, but is formed continuously at the tip side of the first skeletal portion 111. In addition, the second skeletal portion 112 has a braided structure, and is easier to maintain its skeletal shape than the first skeletal portion 111.

In the bare portion 1B, the second skeletal portion 112 is not covered with the coating portion 12, so that when the colonic stent 1 is placed in the large intestine C, the second skeletal portion 112 bites into the wall of the large intestine C and is fixed to the large intestine C. Furthermore, since the second skeletal portion 112 is formed from the same metal wire as the first skeletal portion 111, the skeletal portion 11 is unlikely to be torn apart by the peristaltic movement of the large intestine C, etc.

Moreover, the second skeleton 112 is configured to be expandable and contractable in the axial direction. This allows the bare portion 1B to easily follow the shape changes (such as peristaltic movement) of the large intestine C. Furthermore, it is preferable that the second skeleton 112 is configured to be contractable in diameter in association with the axial extension operation. This also improves the loading property when the colonic stent 1 is housed in the sheath 2.
For example, the metal wire W drawn out from the tip of the first skeletal portion 111 is formed into a corrugated shape, and the second skeletal portion 112 is woven around the periphery of the tip of the first skeletal portion 111 so that the peaks and valleys of each turn do not overlap, thereby making it possible to provide a configuration that is expandable and contractable in the axial direction. Note that the bent portion of the second skeletal portion 112 on the first skeletal portion 111 side may be fixed to the first skeletal portion 111 by crossing so as to mesh with the bent portion on the tip side of the first skeletal portion 111, or may not be fixed to the first skeletal portion 111.

The skeletal portion 11 (particularly the first skeletal portion 111) is configured to be expandable in the axial direction while maintaining its radial size. In this embodiment, the first skeletal portion 111 is formed by spirally winding a metal wire, so that the skeletal portion 11 maintains its radial size by twisting in the spiral direction when expanding and contracting in the axial direction. As a result, even if the skeletal portion 11 expands and contracts in response to the deformation of the large intestine C, the expansion force of the skeletal portion 11 is maintained, so that the lesion site L of the large intestine C can be expanded while remaining at the retention site.

The coating portion 12 is a membrane that forms a flow path for digested matter, and is arranged along the circumferential surface of the first skeletal portion 111. By arranging the coating portion 12 along the circumferential surface of the first skeletal portion 111, it is possible to prevent colon wall cells from leaking into the inside of the colon stent 1, thereby preventing the recurrence of lesions (obstruction and stenosis) in the large intestine C. In addition, the first skeletal portion 111 has a spiral structure that is difficult to maintain its shape by itself, but by providing the coating portion 12, it is possible to maintain the tubular shape of the colon stent 1.

The coating portion 12 is formed, for example, by dipping, by applying a film to the space formed by the wire material constituting the first skeletal portion 111, i.e., to the peripheral surface of the first skeletal portion 111. Also, for example, the coating portion 12 may be formed of a film material and disposed on the outer peripheral surface and inner peripheral surface of the first skeletal portion 111 so as to sandwich the first skeletal portion 111, or may be disposed only on the outer peripheral surface or only on the inner peripheral surface of the first skeletal portion 111.

Examples of materials that can be used to form the coating portion 12 include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate.

The extension restricting portion 13 is formed, for example, of a tape-like long member, and is fixed (for example, by adhesion, etc.) to the circumferential surface (at least one of the inner circumferential surface and the outer circumferential surface) of the first skeletal portion 111 so as to extend across both axial ends of the first skeletal portion 111. In addition, for example, five extension restricting portions 13 are arranged at equal intervals in the circumferential direction.
In addition, the elongation control portion 13 is formed from a biocompatible thread (e.g., polyester thread, etc.) or fabric (woven fabric or knitted fabric), and has a strength capable of controlling the axial elongation of the first skeletal portion 111, at least to the extent that does not impair the radial expandability of the colonic stent 1.

The extension restriction section 13 suppresses the axial extension of the colonic stent 1 when it is contracted radially and accommodated in the sheath 2. In particular, even in a configuration having a second skeleton section 112 that is axially expandable and contractible, the extension restriction section 13 can suppress the axial extension of the first skeleton section 111. As a result, compared to a stent without the extension restriction section 13, the axial length of the colonic stent 1 when accommodated in the sheath 2 is shorter, and the contact area between the colonic stent 1 and the sheath 2 is smaller. Therefore, the frictional resistance when releasing the colonic stent 1 from the sheath 2 is reduced, so that the colonic stent 1 can be easily released from the sheath 2. In addition, the axial shortening rate when the colonic stent 1 is released from the sheath 2 and expanded is reduced, so that the colonic stent 1 can be placed at the desired placement site in the large intestine C.

Figures 3A to 3C are diagrams showing the state changes of the colonic stent 1 when it is placed. Note that in Figures 3A to 3C, the colonic stent 1 is shown diagrammatically, and the distinction between the first skeletal portion 111 and the second skeletal portion 112 is omitted.

When placing the colonic stent 1 at the lesion site L (target site) of the colon C, the sheath 2 and inner rod 3 are inserted from the anal side along a guide wire (not shown) that has been previously introduced into the colon C, and the colonic stent 1 is positioned at the lesion site L (see Figure 3A).

Next, the sheath 2 is moved toward the anus in the positioned state, and the colonic stent 1 is released from the sheath 2 (see Figs. 3B and 3C). The colonic stent 1 gradually expands as it is released from the sheath 2 (see Fig. 3B), and finally reaches a completely expanded state, ensuring the patency of the colon C (see Fig. 3C). After that, although not shown, the engagement between the colonic stent 1 and the inner rod 3 is released, and the inner rod 3 is pulled out, so that the colonic stent 1 is placed at the lesion site L. As shown in Fig. 3C, on the upstream side (mouth side), the bare portion 1B of the colonic stent 1 is in direct contact with the colon C, so that it is less likely to shift from the placement site, and the covered portion 1A is in direct contact with the lesion site L, so that the seepage of cell tissue is suppressed. The colonic stent 1 may be released from the sheath 2 by moving the inner rod 3 in a pushing manner toward the mouth side while the position of the sheath 2 is fixed.

Thus, the colonic stent 1 (stent) according to this embodiment is a stent placed in the large intestine C (biological lumen), and includes a cylindrical skeletal portion 11 formed of metal wire W (wire material) and capable of expanding and contracting in a radial direction substantially perpendicular to the axial direction, and a coating portion 12 arranged along the circumferential surface of the first skeletal portion 111 of the skeletal portion 11. The second skeletal portion 112 of the skeletal portion 11, in which the coating portion 12 is not arranged, has a braided structure made of metal wire W (at least one of the wire materials forming the first skeletal portion 111), and is configured to be expandable and contractable in the axial direction.

According to the colonic stent 1, the second skeletal part 112, in which the coating part 12 is not arranged, is formed in a braided structure using the same metal wire W as the first skeletal part 111, so that the shape of the second skeletal part 112 is well retained, and the possibility that the skeletal part 11 will be cut off by the peristaltic movement of the large intestine C can be reduced, for example, compared to a configuration in which the first skeletal part 111 and the second skeletal part are connected by a connecting part (for example, crimping, etc.). Therefore, the second skeletal part 112 can be appropriately inserted into the wall of the large intestine and can be fixed to the large intestine C for a long period of time. In addition, the second skeletal part 112 is configured to be expandable and contractible in the axial direction, so that it is easy to follow the shape change (peristaltic movement, etc.) of the large intestine C. Furthermore, the skeletal structure of the first skeletal part 111 can be appropriately designed independently of the second skeletal part 112, and flexibility according to the placement site can be ensured.
Therefore, according to the colonic stent 1, the shape of the second framework portion 112 can be well maintained, preventing it from shifting from the placement site in the colon C, and the colonic stent 1 can be well adapted to changes in the shape of the colon C.

The second skeleton 112 is also configured to be able to contract in diameter as it extends in the axial direction. This improves the loading performance when the second skeleton 112 is accommodated in the sheath 2. Furthermore, for example, when the colon C in which the colon stent 1 is placed contracts in diameter, the second skeleton 112 contracts in diameter and the intersecting portion of the metal wire W deforms and bites into the colon wall, making it difficult for the colon stent 1 to come out of the placement site of the colon C.

The first framework 111 also has a helical structure made of metal wire W. This improves the flexibility of the covered portion 1A, which occupies most of the colonic stent 1, and therefore prevents perforation of the colon C when placed in the lesion site L, and prevents the colonic stent 1 from escaping from the placement site due to an inability to follow changes in the shape of the colon C (e.g., bending).

The second skeleton 112 is provided at the upstream end of the skeleton 11 in the flow direction of the fluid flowing through the large intestine C (biological lumen). This allows the second skeleton 112 to be released first from the sheath 2, allowing the covered portion 1A to be released while adjusting the position of the large intestine stent 1 with the bare portion 1B fixing the placement position of the large intestine stent 1 to some extent. In other words, if the covered portion 1A is released first from the sheath 2 and positioned upstream in the flow direction, the covered portion 1A is easily displaced by the fluid flow, making position adjustment difficult, whereas if the bare portion 1B (second skeleton 112) is provided upstream in the flow direction, the placement position of the large intestine stent 1 can be easily adjusted.

The invention made by the inventor has been specifically described above based on the embodiment, but the invention is not limited to the above embodiment and can be modified without departing from the gist of the invention.

For example, the skeletal portion 11 does not have to be made up of a single wire. If the first skeletal portion 111 is made up of multiple wires, it is sufficient that the second skeletal portion 112 is made up of at least one of the wires.

In addition, in the embodiment, the first skeletal portion 111 is formed by spirally winding a metal wire, but the first skeletal portion 111 may also be formed by weaving the metal wire W. In this case, however, care must be taken not to significantly impair the flexibility of the first skeletal portion 111.
In addition, the braided structure of the second skeleton portion 112 is not limited to the structure shown in the embodiment, and may be, for example, a diamond-shaped wire mesh (fence-like). However, the braided structure in which the metal wire W is formed into a corrugated shape and wound around multiple times as in the embodiment is more preferable from the viewpoint of ease of loading into the sheath 2, since it is easier to expand and contract in the axial direction and the diameter reduction accompanying the expansion is large.

The first skeletal portion 111 and the second skeletal portion 112 may be formed from different wires. In this case, for example, the mouth side end of the first skeletal portion 111 and the anus side end of the second skeletal portion 112 may be combined, or the wires of the first skeletal portion 111 and the second skeletal portion 112 may be connected to each other using a crimping member (not shown) or the like.

In addition, in the embodiment, the first skeletal portion 111 has a straight cylindrical shape, but this is merely an example and is not limited to this. The first skeletal portion 111 may have a curved shape according to the placement site, or may have a curved shape that follows the shape of the digestive tract (biological lumen) after placement.

In addition, in the embodiment, a one-side flare type partially covered stent has been exemplified as the large intestine stent 1, but this is merely an example and is not intended to be limiting, and may be modified as appropriate.
The present invention can be applied, for example, to a one- or two-sided flare type partially covered stent, as well as a straight type partially covered stent.

Furthermore, the present invention is not limited to the colon stent 1 described in the embodiment, but can be applied to digestive tract stents placed in the digestive tract, such as the esophagus or large intestine, and further to stent grafts placed in blood vessels. In this case, the fluid flowing through the digestive tract can include, for example, food immediately after ingestion that has not been digested at all, food that has been broken down as it passes through the digestive tract, and food that has passed through the digestive tract but has not been digested (e.g., feces, etc.), regardless of the state of the substance.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

1. Colon stent (stent)
11 Skeleton 12 Membrane 111 First Skeleton 112 Second Skeleton C Large Intestine (Living Lumen)

Claims (4)

A stent to be placed in a biological lumen,
A cylindrical skeleton portion formed of a wire rod and expandable and contractable in a radial direction substantially perpendicular to an axial direction;
a coating portion disposed along a circumferential surface of a first skeletal portion of the skeletal portion,
A second skeletal portion in which the coating portion is not arranged is made of at least one of the wires forming the first skeletal portion, and the wire pulled out from the tip of the first skeletal portion has a braided structure in which the wire forms a wave shape and wraps around the periphery of the tip of the first skeletal portion so that the peaks and valleys of each turn do not overlap, and the stent is configured to be expandable and contractible in the axial direction. The stent according to claim 1, wherein the second framework is configured to be capable of shrinking in diameter in response to the axial extension motion. The stent according to claim 1 or 2, wherein the first framework has a helical structure made of the wire. The stent according to any one of claims 1 to 3, wherein the second framework is provided at an end of the framework that is upstream in the flow direction of the fluid flowing through the biological lumen.

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