JP2003038498A - Biologically absorptive coil for blood vessel blockage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil using a biologically absorptive polymer by solving problems in a coil used for blood vessel blockage which is conventionally made of a metal wire such as stainless wire or platinum wire that the metallic coil generates an artifact by MRI, which is not changed in a living body but semipermanently left in the living body; and when removing the placed part later by a surgical operation, it is often difficult to cut the coil when it is made of the metal wire; and since the placed coil is left in the living body as it is even when the role of the coil is ended, a re-operation is required for the removal of the placed coil. SOLUTION: This biologically absorptive coil is mainly composed of the biologically absorptive polymer. This coil is gradually decomposed by hydrolysis or the like, when placed in the living body for a long period, and extinguished from the living body.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a bioabsorbable coil for use in occluding blood vessels.

[0002]

2. Description of the Related Art A coil used for occluding a blood vessel is used for forming a thrombus in a blood vessel, treating internal bleeding, an aneurysm, and suppressing blood flowing to a tumor. The coil used for these is formed by winding a wire into a thin spiral shape. The spirally wound product may be wound into a larger diameter helical. This coil is linearly inserted into the catheter, and the coil is pushed with a pusher, pushed out from the catheter, and placed at the target site. These coils are described in JP-A-9-276280 and JP-A-2000-502221.

[0003]

The conventional coil is made of metal wire such as stainless wire and platinum wire. The metallic coil causes an artifact in MRI (Magnetic Resonance Imaging) diagnosis to make the diagnosis difficult, and the metallic coil remains unchanged in the living body and remains semi-permanently in the living body. Therefore, when the indwelling portion is later to be cut off by a surgical operation or the like, it may be difficult to cut out because it is a metal wire. Further, even if the role of the placed coil ends, the coil remains as it is in the living body. Then, in order to remove the placed coil, re-operation is required.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to provide a coil using a bioabsorbable polymer for the purpose of solving the problems of the metal coil. The bioabsorbable polymer is an aliphatic polyester bioabsorbable polymer,
Bioabsorbable coil. A bioabsorbable coil, wherein the bioabsorbable polymer is at least one selected from the group consisting of polycaprolactone, polyglycolic acid, polylactic acid, and copolymerization of the polymers.

The present invention is a bioabsorbable coil mainly composed of a bioabsorbable polymer, and when it is left in the living body for a long period of time, it gradually decomposes by hydrolysis and disappears from the living body.
The period until disappearance depends on the in-vivo conditions, the shape of the coil, and the like.

The present invention is a coil formed from a monofilament of a bioabsorbable polymer, the coil passing through the inside of the catheter in a linear shape to reach a target site, and extruded from the catheter to the outside. Sex coil. Further, it is a coil formed from a monofilament of bioabsorbable polymer, the coil is a bioabsorbable coil that passes through the inside of the catheter in a straight line shape to reach a target site and recovers its shape when extruded from the catheter to the outside. is there. The shape to be recovered may be a J curve at the tip, a loop, or a spiral shape as a whole.

According to the present invention, the monofilament has a diameter of 0.
A bioabsorbable coil that is 015 mm to 0.4 mm.

According to another aspect of the present invention, there is provided a coil formed from a monofilament of a bioabsorbable polymer, the coil being a spirally wound coil for vascular occlusion. Also, a bioabsorbable coil for occluding a blood vessel, wherein a spiral wound coil having the primary diameter is further wound.

The diameter of the above monofilament is 0.01
The bioabsorbable coil according to claim 5, which has a length of 5 mm to 0.4 mm.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, a bioabsorbable polymer that constitutes the bioabsorbable filament used in the present invention will be described. In the present invention, the bioabsorbable polymer is preferably an aliphatic polyester bioabsorbable polymer. Examples of the aliphatic polyester-based bioabsorbable polymer include poly (α-lactic acid) and poly (α-lactic acid).
-Hydroxy acid); poly-ε-caprolactone, polydioxanone and the like. These aliphatic polyesters generally have a melting point of 60 to 200 ° C. and a glass transition point of −6.
It has a weight average molecular weight of about 100,000 to 0,000 and 0 to 100 ° C.

Of the above aliphatic polyesters, a polymer selected from polyglycolic acid, polylactic acid, and copolymers of the above polymers has excellent bioabsorbability, high biosafety, and glycolic acid which is a degradation product. Particularly preferred is that lactic acid is absorbed in vivo. Polylactic acid is preferable because it has excellent mechanical strength, good fiber performance, low price, transparency, and good colorability. Regarding bio-safety, not only polylactic acid itself is safe but also it is not necessary to add a plasticizer as in the case of conventional polymer materials, which is also excellent in that respect. Of course, blends selected from polyglycolic acid, polylactic acid, and copolymers of said polymers can also be used.

The polylactic acid is usually preferably poly-L-lactic acid composed of L-lactic acid units. Poly-L-lactic acid has excellent mechanical strength and can obtain desired fiber physical properties.

The polylactic acid may be not only a homopolymer but also a lactic acid-based copolymer in which a lactic acid monomer or another component copolymerizable with lactide is copolymerized. Examples of such other components include dicarboxylic acids having two or more ester bond-forming functional groups, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like.

Polylactic acid can be synthesized by a conventionally known method. That is, JP-A-7-3861, JP-A-59-96123, and Proceedings 44 of Polymer Symposium.
Vol. 3, pp. 3198-3199, or by direct dehydration condensation from lactic acid, or ring-opening polymerization of lactic acid cyclic dimer lactide. Further, in order to promote the bioabsorbability of polylactic acid, it is possible to increase the residual amount of the monomer in the polylactic acid or to add a bioabsorbability promoter into the polymer.

If the aliphatic polyester contains an X-ray contrast agent component (barium sulfate, gold powder, iodine contrast agent, etc.), the coil can be accurately attached to a desired portion, and the treatment process can be observed. Can be performed more accurately.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is composed of a monofilament, and both ends thereof are curved. FIG. 2 is composed of a monofilament, and both ends are looped in a circular shape. FIG. 3 shows a spiral wound coil. In FIG. 4, both ends of the spirally wound coil are J-curved. FIG. 5 shows a further winding of a spiral wound coil having a primary diameter.

The monofilament is produced by extruding from a nozzle of an extruder. The desired diameter of the monofilament is produced by selecting appropriate conditions depending on the nozzle diameter, the resin discharge speed, the drawing speed, and the like. In order to give a J-curve shape as shown in FIG. 1, for example, a linear monofilament is placed in a mold having a J-shaped groove, heated to a temperature close to the melting point, or held in the J shape. It is heat-treated or cooled and then taken out. When this is put into the inside of the catheter as it is, delivered to a desired site, and pushed out from the catheter, the curvature returns to a J-shape although the curvature is slightly increased. Before being placed in the catheter, the J-shaped monofilament is cooled to straighten the J-shaped portion at a temperature (Ts) not lower than the glass transition temperature and not higher than the melting temperature of the polymer, and this straight shape is then fed to the inside of the catheter. Similarly, it may be delivered to a desired site and extruded from the catheter. In this case, the shape of the extruded monofilament is linear immediately after extrusion, but gradually returns to the J shape at body temperature. However, it takes time. The shape of FIG. 2 can also be formed in the same manner as in FIG.

The spiral wound coil of FIG. 3 can be formed by spirally winding a monofilament on a thin metal wire, raising the temperature to a temperature close to the melting point of the polymer, and cooling. This can be placed in a catheter as it is, delivered to a desired site, and extruded from the catheter to leave the coil at the desired site. FIG. 4 is obtained by spirally winding a monofilament on a J-shaped wire at both ends, raising the temperature to a temperature close to the melting point of the polymer, and then cooling. Similarly, in FIG. 5, a coil can be produced by using a wire wound in a large spiral shape. The larger shape of the spirally wound coil does not necessarily have to be a spiral shape and may be a random shape.

The wire used above is stainless steel,
It may be made of a material having a melting point higher than that of the bioabsorbable polymer, such as copper or aluminum. Wire diameter is 0.03mm-2mm, preferably 0.04mm
~ 1 mm. The diameter of the monofilament used above is 0.015 mm to 0.4 mm, preferably 0.02
mm to 0.2 mm. The coil diameter of the above spiral winding is 0.05 mm to 2 mm, preferably 0.07 mm
~ 1 mm. The length of the coil for occluding the blood vessel is 1
cm to 30 cm.

As a method for moving the coil for occluding blood vessels of the present invention to a desired position inside the catheter and releasing the coil from the catheter at that position, various known methods may be adopted. For example, a method of electrically disconnecting the coil and pusher, a method of meshing with a screw, a method of thickening a part of the coil to securely fix the position in the catheter, and releasing the coil from the catheter to a desired position are adopted. it can.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 Poly-L-lactic acid (manufactured by Shimadzu Corporation, trademark Lacty, weight average molecular weight 200,000, melting point 175 ° C.) was 200
Melt spinning at 0 ° C. and stretching were performed to obtain a monofilament having a diameter of 0.15 mm. This monofilament was cut into a length of 8 cm, both ends were wound once around a stainless wire having a diameter of 1 mm, and heat-treated at 150 ° C. This coil is filled with physiological saline, the outer diameter is 1 mm, and the total length is 1
A 10 cm microcatheter was put in the proximal part, and the coil was pushed to the tip part with a pusher, and the coil was extruded to the outside of the ga catheter. The tip of the extruded coil kept a curve.

[Embodiment 2] The diameter of 0.
A poly-L-lactic acid monofilament having a length of 15 mm and a length of 60 cm was spirally wound on a stainless wire having a diameter of 2 mm and heat-treated. After cooling, it was removed from the stainless wire. The length of this spiral coil is about 5
It was cm.

[Embodiment 3] Poly-L-having a diameter of 0.1 mm
A lactic acid monofilament was produced in the same manner as in Example 1. A stainless steel wire with a diameter of 1 mm is put on a spiral wire with a diameter of 4 mm, and a poly-
A monofilament of L-lactic acid was spirally wound, heat-treated and cooled. A coil was obtained with a spiral winding having a primary diameter of 1 mm, which was further spiraled with a diameter of 4 mm.

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, by using a vasoocclusive coil made of a bioabsorbable polymer that is decomposed and absorbed in the body, it is possible to apply to temporary vascular occlusion without causing artifacts in MRI diagnosis. And the trouble of cutting such as a metal coil is lessened when surgically removing a blocked blood vessel.

[0025]

[Brief description of drawings]

FIG. 1 is composed of a monofilament, and both ends thereof are curved.

FIG. 2 is a monofilament in which both ends are circularly looped.

FIG. 3 shows a spiral wound coil.

FIG. 4 shows a J-curve at both ends of a spirally wound coil.

FIG. 5 shows a further winding of a spiral wound coil having a primary diameter.

Claims (10)

[Claims] 1. A bioabsorbable coil for vascular occlusion, which is a coil formed from a monofilament of a bioabsorbable polymer, the coil passing through the inside of a catheter to a target site and being extruded from the catheter to the outside. 2. The bioabsorbable coil for occlusion of a blood vessel according to claim 1, wherein the coil has a shape memory and recovers the shape when pushed out from the catheter. 3. The monofilament has a diameter of 0.015 mm.
To 0.4 mm, the bioabsorbable coil for vascular occlusion according to claim 1 or 2. 4. The bioabsorbable coil for vascular occlusion according to claim 1, wherein the bioabsorbable polymer is an aliphatic polyester bioabsorbable polymer. 5. The bioabsorbable polymer is polylactic acid.
The bioabsorbable coil for vascular occlusion according to claim 1 or 2. 6. A bioabsorbable coil for vascular occlusion according to claim 1, wherein the coil is formed of a monofilament of bioabsorbable polymer, and the coil is a spiral wound coil. 7. A spiral wound coil having a primary diameter,
7. The bioabsorbable coil for vascular occlusion according to claim 6, wherein the spiral wound coil having the primary diameter is further wound. 8. The diameter of the monofilament is 0.015 mm
To 0.4 mm, the bioabsorbable coil for blood vessel occlusion according to claim 6. 9. The bioabsorbable coil for vascular occlusion according to claim 6, wherein the bioabsorbable polymer is an aliphatic polyester bioabsorbable polymer. 10. The bioabsorbable coil for vascular occlusion according to claim 6, wherein the bioabsorbable polymer is polylactic acid.