JPH06189984A - Artificial blood vessel and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance durability against bending and compression forces by forming a coating layer of tubular resin fluoride having mesh-like holes on the external surface of a porous body, with regard to an artificial blood vessel made of a tubular porous body of tetrafluoroethylene resin having a fine fibrous tissue. CONSTITUTION:A tubular resin fluoride coating layer 2 having mesh-like holes 4 is laid on the external surface of a tubular tetrafluoroethylene resin porous body 1 having a fine fibrous tissue made of fibers and knots thereby jointed to each other, thereby manufacturing an artificial blood vessel. In this case, the layer 2 has many groups of notches arranged peripherally on the tubular resin fluoride resin body, and many groups of notches arranged at positions dislocated by the predetermined angle along another peripheral section, alternately laid at equal intervals in a lengthwise direction. The layer 2 is, then, laid on the external surface of the porous body 1 and pulled in a lengthwise direction, thereby opening the notches and forming the mesh-like holes 4. Thereafter, the layer 2 is heated at a temperature equal to or above the melting point of the resin fluoride, thereby being secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial blood vessel composed of a tubular tetrafluoroethylene resin porous body, more specifically, a tubular tetrafluoroethylene resin porous body excellent in resistance to bending and compression. Of artificial blood vessels.

[0002]

2. Description of the Related Art Artificial blood vessels are replacement transplants for filling a defect in a lesion site of a living blood vessel, bypass transplants for bypassing the lesion site to maintain blood circulation, or blood conduits such as short circuits between arteries and veins. Is used as. Conventionally, as a material for an artificial blood vessel, a polyester fiber knitted fabric or a woven fabric having a braided structure, or a tubular tetrafluoroethylene resin porous body having a fine porous structure (hereinafter abbreviated as PTFE porous tube) has been used. .

Among these, the PTFE porous tube is a fine fibrous tissue composed of fibers and nodules connected to each other, that is, the tetrafluoroethylene resin as a raw material is excellent in antithrombogenicity. Since the fiber-nodule porous structure is excellent in biotissue compatibility, it has been put to practical use as an artificial blood vessel in a region having a smaller diameter than that of polyester fiber.

For the purpose of transporting blood through the lumen of the artificial blood vessel, it is essential to maintain the communication state of the lumen. In other words, an artificial blood vessel may be implanted in a living body and always receive pressure from surrounding living tissues, or may pass through a bent part such as a joint, or may be transplanted by bypassing an organ or a bone. Must be resistant to pressure. When the artificial blood vessel is easily bent or crushed, the communication state of the lumen is obstructed and blood flow is blocked.

In particular, in the medium-diameter region where the PTFE porous tube is favored, this is often the case, and thus the maintainability of the lumen is important. On the other hand, an artificial blood vessel is required to have easy passage of a suture needle and sutureability with a living blood vessel, and therefore it is not possible to excessively thicken the tube wall or harden the material, so that it has sufficient resistance to bending and compression. Granting is
It was difficult.

To solve these problems, (1) a method of attaching a ring-shaped or spiral-shaped reinforcement to the periphery of the PTFE porous tube, (2) heat treatment of the outer surface of the PTFE porous tube, and unevenness on the outer surface A method of providing a structure (Japanese Patent Publication No. 58-1656) has been proposed. However, in the method of (1), even if the strength of the reinforcement itself is high, when a diagonal force is applied to the ring-shaped or spiral-shaped reinforcement, these reinforcements are It falls at an angle and cannot maintain the lumen. Further, in the method (2), although the inner cavity is maintained well, the layer of the uneven structure on the outer surface provided for reinforcement is integrated with the PTFE porous tube body, so that the whole artificial blood vessel is hard. In addition, the reinforcement portion cannot be removed at the stitched portion that requires softness. Therefore,
The method (2) has a problem in that the sutureability of the artificial blood vessel is insufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an artificial blood vessel made of a tubular tetrafluoroethylene resin porous body which has excellent resistance to bending and compression and excellent sutureability. Moreover, the objective of this invention is providing the manufacturing method of the artificial blood vessel which has the said characteristic.

The present inventor, in the course of research for overcoming the above-mentioned problems of the prior art, in the conventional ring-shaped or spiral-shaped reinforcement, the tube longitudinal direction in between the rings or between the spiral windings. I didn't get in touch, so
We paid attention to the fact that when bending or pressure is applied, the reinforcement falls down in the long axis direction and occludes the lumen.

Therefore, as a result of conducting research, the present inventor found that
The outer surface of the PTFE porous tube is provided with a coating layer of a tubular fluororesin body having mesh-like holes, so that it has sufficient shape-maintaining strength in the circumferential direction, good resistance to pressure, and long-axis direction. It has been found that an artificial blood vessel having appropriate elastic flexibility and capable of bending while maintaining the lumen can be obtained.

Further, a tubular fluororesin body having a large number of cuts is stretched in the long axis direction to form a coating layer having a mesh structure, or a concavo-convex structure is formed on the outer layer of a PTFE porous tube having a two-layer structure by heat treatment. To form a mesh structure, the reinforcing layer having mesh holes and the PTFE porous tube body are integrated, and at the sutured portion, the reinforcing portion of the artificial blood vessel can be removed. It was found that it can be obtained. The present invention has been completed based on these findings.

[0011]

Thus, according to the present invention, an artificial body composed of a tubular tetrafluoroethylene resin porous body having a fine fibrous structure composed of fibers and nodules connected to each other by the fibers. A blood vessel is provided with an artificial blood vessel characterized in that a coating layer of a tubular fluororesin body having mesh-like pores is provided on the outer surface of the tubular tetrafluoroethylene resin porous body.

Further, according to the present invention, (1) two cuts having the same length are formed along the circumference of the tubular fluororesin body.
A group of notches [A] arranged at equal intervals within a range of up to 4 and another notch of the same length and number as described above along another circle at a position separated from the circumference by a certain distance, 18
A plurality of cut groups [B], which are arranged at positions displaced by an angle obtained by dividing 0 degree by the number of cuts, are arranged alternately at equal intervals along the long axis direction of the tubular fluororesin body. A tubular fluororesin body is prepared, and then (2) the tubular fluororesin body has an outer surface of a tubular tetrafluoroethylene resin porous body having a fine fibrous structure composed of fibers and knots connected to each other by the fibers. Over, and by pulling in the long axis direction to open the notches to form a mesh-like hole, and reduce the diameter to make it adhere to the outer surface of the tubular tetrafluoroethylene resin porous body, and then ( 3) Heating at a temperature above the melting point of the fluororesin forming the tubular fluororesin body,
There is provided a method for producing an artificial blood vessel, which comprises fixing a coating layer of a tubular fluororesin body having mesh-like holes to the outer surface of a tubular tetrafluoroethylene resin porous body.

Further, according to the present invention, (1) a mixture of a high molecular weight unsintered powder of tetrafluoroethylene resin and a liquid lubricant, a low molecular weight unsintered powder of tetrafluoroethylene resin and a liquid lubricant And a mixture of and are co-extruded to form a laminated tube consisting of an inner layer containing a high molecular weight tetrafluoroethylene resin and an outer layer containing a low molecular weight tetrafluoroethylene resin,
(2) Laminated tube having a fine fibrous structure composed of fibers and nodules connected to each other by stretching the laminated tube in the at least uniaxial direction with or without removing the liquid lubricant. (3) When the obtained laminated tubular tetrafluoroethylene resin porous body is heat-sintered or after heat-sintering in a heat shrink-preventing state, at least the outer layer is about 327. An artificial blood vessel characterized by forming a coating layer having reticulated pores by heating to a temperature of ℃ or higher and providing a portion where fine fibrous tissue has been cut / contracted and / or decomposed and removed in the outer layer. A method of manufacturing the same is provided.

Furthermore, according to the present invention, a tubular tetrafluoroethylene resin porous body (a) having a fine fibrous structure composed of fibers and nodules connected to each other by the fibers.
Is prepared by using a tetrafluoroethylene resin having a molecular weight lower than that of the tetrafluoroethylene resin forming the porous body (a), and a tubular tetrafluoroethylene resin porous body (having a similar fine fibrous structure ( b), and then at least the porous body (b) is heated to a temperature of about 327 ° C. or higher to cut / shrink and / or decompose and remove the fine fibrous tissue in the porous body (b). By providing the portion, a method for producing an artificial blood vessel is provided, which comprises forming a coating layer having mesh holes.

Further, according to the present invention, a tubular tetrafluoroethylene resin porous body (a) having a fine fibrous structure composed of fibers and nodules connected to each other by the fibers is preliminarily formed on the outer surface of the fine fibers. The same tubular tetrafluoride ethylene resin porous body (b) having a portion where the tissue-like tissue has been cut / contracted and / or decomposed and removed is coated, and then at least the porous body (b) is heated to about 327 ° C. or higher. By heating to a temperature and providing a portion in which the fine fibrous structure is cut / contracted and / or decomposed and removed over the entire surface of the porous body (b) from the outer surface to the inner surface, a coating layer having mesh-like pores is formed. Provided is a method for producing an artificial blood vessel, which comprises forming the artificial blood vessel.

The present invention will be described in detail below. The artificial blood vessel of the present invention has a basic structure of a tubular tetrafluoroethylene resin porous body having a fine fibrous structure composed of fibers and nodules connected to each other by the fibers. PT by the method described in -13560
It can be manufactured by producing a FE porous tube and then performing a treatment of forming a mesh reinforcement on the outer surface.

To make a PTFE porous tube,
First, a liquid lubricant is mixed with PTFE unsintered powder, and a tube is preformed by extrusion and rolling. The liquid lubricant is removed from the molded body or is stretched in at least uniaxial direction without being removed. Next, in a state where the molded body is fixed so as not to shrink, it is heated to 327 ° C. or higher, which is the melting point of the resin, and the stretched structure is sintered and fixed to obtain a PTFE porous tube having improved strength. This PT
The FE porous tube has a fine fibrous tissue composed of fibers and nodules connected to each other by the fibers, and the tissue imparts a porous structure.

The artificial blood vessel of the present invention has a P
It can be obtained by providing a mesh-like reinforcing portion on the outer surface of the artificial blood vessel made of TFE porous tube, and it is important that this reinforcing portion has the following characteristics. Sufficient shape retention strength in the circumferential direction to maintain tubular structure against compression. Appropriate elastic flexibility in the longitudinal direction to accommodate bending. At the sewn part, the reinforcing part is an obstacle, so that the reinforcing layer can be easily partially removed. As a first method for obtaining an artificial blood vessel satisfying the above characteristics (1) to (4), the following manufacturing methods can be mentioned.

(1) Along the circumference of the tubular fluororesin body, notches of the same length are arranged at equal intervals within a range of 2 to 4. This is called a notch group [A]. (2) Along the other circumference, which is a certain distance away from the circumference, cuts having the same length and number as the above are arranged at positions shifted by an angle obtained by dividing 180 degrees by the number of cuts. . This is called a notch group [B]. (3) A tubular fluororesin body having a structure in which a large number of the cut groups [A] and [B] are alternately arranged at equal intervals along the major axis direction of the tubular fluororesin body is prepared. (4) PT the tubular fluororesin body with many cuts
By covering the outer surface of the FE porous tube and pulling it in the long axis direction, the slit is opened to form a mesh-like hole. At that time, the diameter of the tubular fluororesin body is reduced and PT
It adheres to the outer surface of the FE porous tube. It should be noted that before the tubular fluororesin body is covered with the PTFE porous tube, the cut may be preliminarily opened by pulling in the long axis direction, but in that case, when the PTFE porous tube is covered, the cut is not formed. The operation is easy if the tubular fluororesin body is expanded to its original size by contracting in the long axis direction so as to be closed. (5) By heating at a temperature equal to or higher than the melting point of the fluororesin forming the tubular fluororesin body, the coating layer of the tubular fluororesin body having mesh-like holes is fixed to the outer surface of the PTFE porous tube.

Through the above steps, the tubular fluororesin body is
The cuts are extended to form a leaf-shaped hole in the tree, and the portion between the cuts serves as a connecting portion that connects the columns that form a net. In this net-like structure, the notch is in the circumferential direction, and since it is formed by extending it in the major axis direction, the strength of the original tubular fluororesin body in the major axis direction is divided and weakened. It has a pseudo-elasticity based on the network structure and retains the strength of the original tubular fluororesin body in the circumferential direction.
That is, the coating layer of the tubular fluororesin body having the mesh-like holes has a structure satisfying at least the above-mentioned and necessary conditions concerning the strength characteristics.

It is difficult to form such a structure having different strengths depending on the directions by simply making holes in the reinforcing material or knitting a thread-shaped material in a net shape. Therefore, a plurality of cuts formed along the circumference of the tubular fluororesin body are provided so that the positions of the cuts are alternately different along the major axis direction, and the tubular fluororesin body is arranged in the major axis direction. A coating layer in which the notches are opened by pulling to form a mesh-like hole is preferable.

Practically, in order to obtain the above effects with such a network structure, it is desirable that the network structure has a shape within a certain range. Although it depends on the aperture,
Unless the wall thickness of the PTFE porous tube-made artificial blood vessel itself is usually set to about 300 to 1500 μm, problems occur in sutureability and flexibility. According to the study of the inventor, even if the reinforcing layer of the sutured portion is removed and used, the thickness of the reticulated tubular fluororesin body is preferably 1000 μm or less in view of the balance with the wall thickness of the artificial blood vessel. On the other hand, in order to maintain the strength in the circumferential direction, a thickness of 300 μm or more is necessary, depending on the kind of the fluororesin body. Therefore, the thickness of the reticulated tubular fluororesin body is practically in the range of 300 to 1000 μm. Also, considering that the net-like structure needs to reinforce the strength in the circumferential direction and be soft in the major axis direction, each strut forming the net-like structure should not be inclined by 45 degrees or more from the circumferential direction. Is preferred.

Furthermore, when the number of holes in the mesh structure is four or more in the circumferential direction, or the maximum width of the holes is 1 mm or less,
The flexibility with respect to bending is not sufficient, and even if the thickness of the tubular fluororesin body is reduced in order to improve the flexibility, the strength reinforcement in the circumferential direction becomes small this time, resulting in poor balance. Therefore, the number of mesh holes is preferably in the range of 5 to 30 per cm of the artificial blood vessel.

In the same tubular fluororesin body, the lengths of the cuts are the same, and the intervals between the cuts and the intervals between the cut groups are equal to each other. There may be an error of about%.

The reticulated tubular fluororesin body obtained as described above is coated on the outer surface of the PTFE porous tube and heated to a temperature above the melting point of the fluororesin to melt and bond them. At this time, the reticulated tubular fluororesin body is made to have a larger diameter than the PTFE porous tube to be coated in advance, and after being coated on the PTFE porous tube, it is pulled in the long axis direction to sufficiently reduce the diameter. If both are brought into close contact with each other, this fixing can be easily performed.

When the heating conditions are selected such that the surface of the reticulated tubular fluororesin body is melted, the two are not easily peeled off when they are bent or pressed against the entire artificial blood vessel, but the reticulated tubular fluororesin is bonded. By pulling a part of the support of the resin body, it is possible to relatively easily peel off only the covering part of the part.

Although the reticulated tubular fluororesin body alone stretches in a slender shape when pulled in the long axis direction, PT
After being fixed to the FE porous tube, the shape is restricted while maintaining the pseudoelasticity based on the network structure. Therefore, if you hold only the whole column by hand and pull on only some of the braided tubular fluororesin bodies, the notches right next to the braces become deeper and finally line up in the circumferential direction. The notches are connected to each other and can be separated in the circumferential direction.

As described above, the tubular structure of the tubular fluororesin body having a shape in which the notch in the circumferential direction is extended has the above-mentioned characteristic, that is, the characteristic that the reinforcing material can be easily partially removed at the seam. Also works to your advantage.

The material of the reticulated reinforcing body capable of exhibiting the above-mentioned characteristics is PTF which is a material for implantation in a living body or an artificial blood vessel.
Considering the adhesiveness with E, a fluorine resin is preferable, and among them, PTFE, FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-fully-fluorinated alkyl vinyl ether copolymer), ETFE (tetrafluoroethylene-ethylene copolymer) and the like are particularly desirable.

As the second method for obtaining the artificial blood vessel of the present invention, the method described in Japanese Patent Publication No. 58-1656 mentioned above, that is, a part of the PTFE porous body is heated at a higher temperature than other parts in the heating and sintering step. After treating or uniformly heating and sintering the whole, a part of the PTFE porous body is further heated to cause cutting of fine fibers, fusion bonding, fusion bonding of nodules due to contraction between nodules, etc. Can be used.

When a portion of the PTFE porous body is heated to about 327 ° C. or higher by this method, the PTFE fibers are cut by the heat to spread the internodal spaces into recesses, and the other internodal spaces shrink and the internodal spaces shift. Collectively, a strong protrusion is formed. Generally, in the case of a PTFE porous tube, the fibers have a structure oriented in the long axis direction of the tube, and the nodules are oriented in the circumferential direction, so that the convex portions are formed in a mountain range long in the circumferential direction. In this mountain range, the places are joined or joined.
Since it has a branched structure, it is a "leaf-like hole" formed by the first method described above, although the shape and size are not uniform.
A recess having a shape similar to that of is formed. Therefore, even if this method is used, PTF that is sufficiently resistant to pressure and bending.
E It is possible to form a porous tube, but it has the drawback of poor sutureability because it becomes stiff overall.

The drawback is that the PTFE porous tube is
This can be solved by adopting a method of forming a concavo-convex structure only on the outer layer by heat treatment after layering.
In other words, according to the method described in Japanese Patent Publication No. 58-1656,
When the PTFE porous tube having a two-layer structure is subjected to a heat treatment for surface treatment, it is possible to impart a necessary uneven structure only to the outer layer by controlling the treatment temperature and the like. Then, when the concave portion formed from the surface during heat treatment is penetrated through the tube wall of the outer layer to reach the laminated interface with the inner layer,
The outer layer can be a coating layer of a tubular fluororesin body having mesh holes.

The formation of the concavo-convex structure by the surface processing largely depends on the molecular weight of the PTFE used, and the low molecular weight PTFE requires a small amount of heat to form the concavities and convexities. Grows larger. Therefore, in the present invention, by utilizing this phenomenon, (1)
In the extrusion process of manufacturing PTFE porous tube,
Inner layer containing high molecular weight PTFE and low molecular weight PTFE
After making a laminated tube consisting of an outer layer containing the, and stretching, heat treatment of the outer layer, or (2) PTFE porous tube is a PTFE porous tube made by using PTFE having a lower molecular weight than that. Coated, then
By heat-treating the outer layer, the cut / shrinked and / or decomposed and removed portion of the fine fibrous tissue is formed in the outer layer.

By forming the concavo-convex structure on the outer layer by this method, formation of the reticulated tubular fluororesin body and fixing to the PTFE porous tube can be performed at once. That is, since the coated PTFE porous tube has a low molecular weight, it is surface-treated more quickly during the heat treatment, and the coated PTFE porous tube is coated before the porous structure of the high molecular weight PTFE porous tube of the coated inner layer changes. It is possible to complete the reticulation of the tube.

According to the results of the study by the present inventor, these manufacturing methods can be easily carried out if there is a difference in molecular weight of about 1.5 times between the PTFE of the inner layer and the PTFE of the outer layer. For example, commercially available PTFE includes CD123, CD1 and CD4 (manufactured by Asahi Glass Co., Ltd., molecular weights of 1200 to 15 million and 200 million, respectively).
~ 123 million, 20-300,000), F104 (manufactured by Daikin, molecular weight of about 4 million), etc., CD123 / F1
04 (molecular weight ratio = 3 to 4 times), CD123 / CD1 (molecular weight ratio = 4 to 8 times), CD123 / CD4 (molecular weight ratio =
40-75 times), F104 / CD1 (molecular weight ratio = 1.3
~ 2 times), F104 / CD4 (molecular weight ratio = 4 to 8 times),
Any combination such as CD1 / CD4 (molecular weight ratio = 7 to 15 times) is possible. However, when the molecular weight is as low as CD4, the heating conditions for the surface treatment are very limited,
Further, if there is an extremely large difference in molecular weight like the combination of CD123 / CD4, in the method of forming multiple layers at the time of extrusion, when the heat amount necessary for sintering CD123 of the inner layer is given, the C of the outer layer is
Since D4 is almost decomposed and does not form a porous structure, only a method of coating after sintering is possible. On the contrary, in the combination of F104 / CD1 with a small difference in molecular weight,
The heating conditions for providing the uneven structure only on the CD1 layer are limited.

Therefore, two kinds of PTFE to be combined
The molecular weight ratio is preferably 1.5 times or more, preferably 2 to 40 times, and more preferably 3 to 8 times in terms of operability.

In addition to the method of shifting the treatment time depending on the difference in the molecular weight, the portion of the tubular tetrafluoroethylene resin porous body to be extrapolated on which the fine fibrous tissue has been cut / contracted and / or decomposed / removed in advance is removed. There is a way to set it up. Cutting / shrinking and / or decomposition and removal of the fine fibrous tissue by heating the outer surface gradually progresses from the outer surface to the inner surface.
The speed is largely related to heat transfer to the object existing on the inner surface. In other words, if there is a good heat transfer material such as metal on the inner surface, the heat transferred near the inner surface escapes to the metal.
The temperature does not rise and there is a temperature gradient inside and outside. This temperature gradient allows the process to proceed relatively slowly from the outer surface to the inner surface, making it industrially controllable. If the outer surface formed by this method has a fine fibrous structure cut and shrunk and / or decomposed and removed, the tubular porous body with irregularities should have a poor heat transfer property such as a tetrafluoroethylene resin porous body. When they are brought into close contact with each other and only in contact with each other but not in contact with each other, the cutting / shrinking and / or decomposition / removal of the fine fibrous tissue proceeds to the inner surface all at once by heating.

Then, the tubular tetrafluoroethylene resin porous body to be coated is previously cut, shrunk and / or decomposed and removed on the outer surface of the porous body, and after coating, it is heated to a temperature of at least about 327 ° C. or higher. Then, the cut and shrunk and / or decomposed and removed portion of the fine fibrous tissue can be provided on the entire surface of the coated porous body from the outer surface to the inner surface, and the inner layer and the outer layer are tubular tetrafluoroethylene resin porous materials having the same molecular weight. Even if a porous material is used, or if the treatment time and wall thickness vary somewhat, the outer surface of the tubular tetrafluoroethylene resin porous material
It is possible to industrially produce an artificial blood vessel having a structure in which a tubular fluororesin covering layer having mesh-like holes is uniformly provided.

The product of the present invention thus obtained has the same high maintainability of the lumen structure as that obtained by the method described in Japanese Patent Publication No. 58-1656, and the reinforcing portion covering the outer surface is the same. It is possible to remove relatively easily by pulling only a part. However, this Japanese Patent Sho 58-165
In the application of the method described in No. 6, since the mesh shape is not uniform, the cut end of the reinforcing portion is likely to be uneven,
Due to the manufacturing process, PTFE is decomposed, and the thickness of the protrusion is 500.
Since it is difficult to make the thickness of μm or more, the first method of making a cut in the tubular fluororesin body is stronger in compression and bending, and is relatively advantageous.

The artificial blood vessel of the present invention has the following features. (1) The shape-maintaining strength is high in the circumferential direction, and the tubular shape retainability against compression is high. (2) It has appropriate elastic flexibility in the long axis direction and can cope with bending. (3) The partial reinforcing layer can be easily removed without impairing the sutureability. Further, since the product of the present invention has the connection in the long axis direction as compared with the conventional reinforcing method, the reinforcing product does not fall sideways and has high resistance to compression.

[0041]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The methods for measuring the physical properties are as follows. <Bubble point> The pressure at which bubbles first appear when the artificial blood vessel is impregnated with isopropyl alcohol and the inside of the tube wall is filled with isopropyl alcohol, and then air pressure is gradually applied from the inside of the tube. <Leakage pressure> The water pressure when water comes out from the outer wall of the artificial blood vessel for the first time when the water pressure is gradually applied from the inside of the artificial blood vessel. <Compressive strength> A value obtained by dividing the maximum drag force by the unit length of the artificial blood vessel when the artificial blood vessel is sandwiched between two parallel plates and compressed to a width of 1/2 of the outer diameter. <Kink diameter> The outer diameter of the cylinder when the diameter of the portion where the outer diameter of the artificial blood vessel is the minimum is 80% of the original diameter when the outer wall of the artificial blood vessel is wound around the cylinder of a certain value.

[Example 1] PTFE fine powder (PTFE fine powder F10 manufactured by Daikin Industries, Ltd.)
4) With respect to 100 parts by weight, 23 parts by weight of dryzole was mixed as an auxiliary agent, and the mixture was molded into a tube by a ram extruder, and then the dryzole was dried at 50 ° C. for 48 hours. This extruded tube was stretched by 350% while being heated in an electric furnace under the conditions of a furnace temperature of 350 ° C. and a residence time in the furnace of 120 seconds, a porosity of 75%, an average fiber length of 30 μm, and an inner diameter of 6 mm.
A PTFE porous tube having a diameter of φ and an outer diameter of 7.5 mm was obtained.

On the other hand, P having an inner diameter of 8 mmφ and an outer diameter of 10 mmφ
TFE non-porous tube, 1mm distance in the circumferential direction
As a result, two notches of less than 15 mm were made. On the circumference 1 mm away from this circumference, two cuts of the same size were also made at the position rotated 90 degrees about the tube long axis from the previous cut. This operation was performed over the entire length of the PTFE non-porous tube in the long axis direction to obtain a tubular fluororesin body having a large number of cuts as shown in FIG.

6 mmφ in the lumen of PTFE porous tube
After inserting the stainless steel rod, the tubular fluororesin body is covered, and the tubular fluororesin body is stretched four times in the long axis direction, and at the same time the notches are opened like a mesh as shown in Fig. 2-2.
The inner diameter was reduced, and the PTFE porous tube was brought into close contact with and fixed to a PTFE porous tube, and placed in a high temperature bath at 350 ° C. for 2 minutes for heat fusion.

As a result, the inner diameter was 6 mmφ, the reticulated tubular fluororesin body covered portion outer diameter was 9.5 mmφ, and the uncoated portion outer diameter was 7.5 mm.
An artificial blood vessel having a diameter of φ, a thickness of the covered reticulated tubular fluororesin body of 1 mm, a maximum hole width in the major axis direction of 3 mm, a number of holes in the circumferential direction of 2 and an angle of about 20 degrees with the major axis direction of each strut was obtained.

[Example 2] The inner diameter of the tubular fluororesin body was 8 m.
mφ, outer diameter is 9mmφ, 4 notches with 6.5mm length are arranged in the circumferential direction, and the width between the notches next to them is 0.5mm,
In the same manner as in Example 1, except that the shift angle was 45 degrees and the extension for the slit opening was doubled.
Inner diameter 6 mmφ, reticulated tubular fluororesin body coating outer diameter 8.5 m
mφ, non-coated portion outer diameter 7.5 mmφ, coated reticulated tubular fluororesin body thickness 0.5 mm, maximum axial width 1 m
m, the number of holes in the circumferential direction was 4, and an artificial blood vessel having an angle of about 20 degrees with the long axis direction of each column was obtained.

[Example 3] PTFE fine powder (PTFE fine powder F10 manufactured by Daikin Industries, Ltd.)
4) A mixture of 100 parts by weight of DRYSOL and 25 parts by weight of an auxiliary agent, and PTFE fine powder (PTF fine powder CD4 manufactured by Asahi Glass Co., Ltd.) 100
A mixture of 18 parts by weight of dryzole as an auxiliary agent with respect to parts by weight is preformed so that the former is an outer layer,
After molding into a two-layer tube having an inner / outer layer ratio of 1: 1 by a ram extruder, DRYSOL was dried at 50 ° C. for 48 hours. This extruded tube was placed in an electric furnace at a furnace temperature of 350 ° C.
350% stretching while heating under the condition that the residence time in the furnace is 120 seconds, average porosity 75%, inner surface fiber length 30 μm, inner diameter 6
A PTFE porous tube having a diameter of mmφ and an outer diameter of 9.5 mmφ was obtained.

6 m in the lumen of this PTFE porous tube
After inserting the mφ stainless steel rod and fixing both ends,
In an electric furnace with a 5 mmφ quartz glass cylinder inserted in the furnace core,
Heat treatment was performed under the conditions of a furnace temperature of 500 ° C. and a residence time in the furnace of 10 seconds, and the tube outer layer was processed into a net-like structure in the process shown in FIG.

[Example 4] PTFE fine powder (PTFE fine powder CD123 manufactured by Asahi Glass Co., Ltd.) 1
25 parts by weight of dryzole was mixed with 00 parts by weight as an auxiliary agent and molded into a tube by a ram extruder, and then the dryzole was dried at 50 ° C. for 48 hours.
This extruded tube was stretched 600% in an electric furnace while being heated at a furnace temperature of 360 ° C. and a residence time in the furnace of 180 seconds, and was stretched 600% to have a porosity of 75%, an average fiber length of 30 μm, an inner diameter of 6 mmφ, and an outer diameter of 7.5 mmφ. A porous tube was obtained.

PTFE fine powder (P made by Asahi Glass Co., Ltd.
20 parts by weight of DRYSOL was mixed with 100 parts by weight of TFE fine powder CD1) as an auxiliary agent and molded into a tube by a ram extruder, and then DRYSOL was dried at 50 ° C. for 48 hours. This extruded tube was stretched by 350% while being heated in an electric furnace under conditions of a furnace temperature of 350 ° C. and a residence time in the furnace of 100 seconds, and an inner diameter of 7.5 mmφ,
A PTFE porous tube having an outer diameter of 9.5 mmφ was obtained. A stainless steel rod having an outer diameter of 8 mmφ was gradually inserted into this tube lumen, and then this was removed to expand the inner diameter to 7.8 mmφ.

Of the above two types of PTFE porous tubes, a 6 mmφ stainless rod was inserted into the former lumen, and then the latter was entirely inserted to fix both ends. Then, heat treatment was performed in an electric furnace in which a quartz glass cylinder having an inner diameter of 35 mmφ was inserted in a furnace core under the conditions of a furnace temperature of 500 ° C. and a residence time in the furnace of 300 seconds, and the tube outer layer was processed into a reticulated structure in the process shown in FIG. .

[Example 5] PTFE fine powder (PTFE fine powder F10 manufactured by Daikin Industries, Ltd.)
4) Liquid lubricant (S manufactured by Esso Co.) with respect to 100 parts by weight.
25 parts by weight of S dry sol) was mixed and molded into a tube by a ram extruder, and then the liquid lubricant was dried.
This extruded tube was stretched by 350% in an electric furnace while heating at a furnace temperature of 350 ° C. and a residence time in the furnace of 100 seconds to obtain a porous PTFE tube having an inner diameter of 3.5 mmφ and an outer diameter of 4.3 mmφ. A 4 mmφ stainless rod was inserted into the lumen of this tube.

On the outer surface of this tube, an artificial blood vessel made of tetrafluoroethylene resin having an inner diameter of 5 mmφ (Technograft manufactured by Sumitomo Electric Industries, Ltd.) having a portion where the fine fibrous tissue is cut, shrunk and / or decomposed and removed is formed on the outer surface. Coated, about 3-4 cm
It was attached to the insertion tube by twisting in the circumferential direction at a pitch of / circle. Next, heat treatment was performed in an electric furnace in which a quartz glass cylinder having an inner diameter of 35 mmφ was inserted into the furnace core under the conditions of a furnace temperature of 750 ° C. and a residence time in the furnace of 50 seconds, and the tube outer layer was treated as shown in FIG.
It was processed into a reticulated structure in the process shown from 2 to 3-3.

Comparative Example 1 Porosity of 7 used in Example 1
5%, average fiber length 30 μm, inner diameter 6 mmφ, outer diameter 7.5
A PTFE porous tube of mmφ was used as Comparative Example 1.

[Comparative Example 2] In Example 4, the heat treatment conditions in an electric furnace in which a quartz glass cylinder was inserted in the furnace core were a furnace temperature of 350 ° C., a residence time in the furnace of 120 seconds, and PT of the inner and outer layers.
Only the FE porous tube was heat-sealed, and the outer layer was not reticulated.

Comparative Example 3 Instead of the PTFE non-porous tube used in Example 1, an inner diameter of 7.3 mmφ and an outer diameter of 9.
A 3 mmφ PTFE non-porous tube was cut into a ring shape having a width of 1 mm, and the P-shaped tube used in Example 1 was cut at 3 mm intervals.
An artificial blood vessel was prepared in the same manner as in Example 1 except that the outer surface of the TFE porous tube was coated and the same heat treatment as in Example 1 was performed, and a ring-shaped fluororesin body was used as a reinforcing means.

[Comparative Example 4] The ring-shaped P used in Comparative Example 3
An artificial blood vessel was obtained in the same manner as in Comparative Example 2 except that the TFE non-porous body was coated at 1 cm intervals.

[Comparative Example 5] The PTFE non-porous tube used in Example 1 was cut into a spiral shape with a width of 1 mm, which was wound around the outer surface of the PTFE porous tube used in Example 1 at a pitch of 3 mm. An artificial blood vessel was obtained in the same manner as in Example 1 except that the coating and the same heat treatment as in Example 1 were performed, and a spiral fluororesin body was used as a reinforcing means.

[Comparative Example 6] An artificial blood vessel was obtained in the same manner as in Comparative Example 2 except that the spiral PTFE non-porous material used in Comparative Example 5 was wound and coated at a pitch of 1 cm.

<Results of Measurement of Physical Properties> (1) Bubble points and water leak pressures of the artificial blood vessels of Examples 1 to 5 and Comparative Examples 1 to 6 were measured and found to be 0.10 to 0.12, 0. It was within the range of 0.25 to 0.30 and there was no significant difference.

(2) The measurement results of the compression strength are 61 g / c for the artificial blood vessels of Comparative Examples 1, 2, 4, and 6, respectively.
m, 93 g / cm, 179 g / cm, and 185 g / cm, whereas the artificial blood vessels of Examples 1 to 5 have 535 g / cm, 645 g / cm, and 247 g / c, respectively.
m, 376 g / cm, 499 g / cm, which was extremely high. For the artificial blood vessels of Comparative Examples 3 and 5, each 32
3 g / cm and 277 g / cm, which were similar to those in the example.

(3) As a result of measuring the kink diameter,
The artificial blood vessels of ˜5 each had a diameter of 6.5 mmφ, and the lumen structure was highly maintainable even when bent, and the artificial blood vessels of Examples 1 and 2 had a diameter of 8 mmφ and 7.5 mmφ, respectively.
On the other hand, in the artificial blood vessels of Comparative Examples 1, 2, 4, and 6, 25 mmφ, 21 mmφ, 12 mmφ, 1
It was 6 mmφ, and the maintainability of the lumen structure was poor. Also,
Regarding the artificial blood vessels of Comparative Examples 3 and 5, since the tube wall is rigid, the resistance against bending is very strong, but once bent, the artificial blood vessels will buckle. Therefore, both kink diameters are 40 m.
Above mφ, it was considered impossible to apply it to a site that requires bending.

(4) When the releasability of the fluororesin body of the reinforced portion was evaluated, the artificial blood vessels of Examples 1 to 5 and Comparative Examples 1, 2 and 5 were treated with the outer layer even after repeating bending of 15 mmR 30 times. In the artificial blood vessels of Comparative Examples 3, 4, and 6, peeling of the fluororesin body of the reinforcing portion was observed, whereas peeling and separation of the inner layer were not observed, and particularly in the artificial blood vessel of Comparative Example 4,
Some rings have completely detached.

When the end of the outer layer or the reinforcing portion was pinched with tweezers and pulled, in any of the examples except the artificial blood vessels of Comparative Examples 5 and 6, it was possible to remove the outer layer or the reinforcing portion from the pulled portion. there were. In the artificial blood vessels of Comparative Examples 5 and 6, since the spiral is dissolved and taken out, it is considered possible to peel off the unnecessary portion of the spiral and cut it with scissors when the reinforcing portion is an obstacle at the sutured portion. ,
It was difficult to cut off the PTFE porous tube of the inner layer without damaging it. On the contrary, when the PTFE porous tube was peeled off sufficiently and cut, the end of the remaining spiral was separated from the PTFE porous tube. As described above, the artificial blood vessels of Comparative Examples 5 and 6 were inferior in operability because the work of removing the reinforcing portion was complicated.

In Example 5 of Examples 1 to 5, the outer layer of the net-like structure is well connected in the circumferential direction, and the net-like outer layer having a width corresponding to the width of the outer layer picked with tweezers is relatively ring-shaped. Easy and easy to operate. As described above, the artificial blood vessels of the examples of the present invention both satisfy both the compression resistance and the maintainability of the lumen structure against bending,
In the artificial blood vessel of the comparative example, if one of the characteristics is excellent, the other does not hold. Further, it can be seen that also in the removability of the reinforcing part, the example is superior.

[0067]

The artificial blood vessel of the present invention has the following characteristics. (1) Since the shape maintaining strength is sufficient in the circumferential direction, the lumen structure is highly maintainable against compression. (2) Since it has appropriate elastic flexibility in the long axis direction, it can be bent according to the bent portion, and the lumen structure is highly maintainable even when bent with a small radius R. (3) Since the reinforcing material is an integral one, the adhesive strength as a whole is strong, and the reinforcing material does not peel off or come off even if the shape is changed. The reinforcement can be easily removed.

Therefore, the product of the present invention is an artificial blood vessel to be transplanted in a living body, particularly an artificial blood vessel used when adaptability and resistance to pressure and flexion are required, such as blood vessel replacement over joints and bones and bypass formation. Is especially effective as Further, although the object of the present invention is an artificial blood vessel, considering that the characteristic of the present invention is high maintainability of its luminal structure, all tubular organs in the living body, for example, digestive tract, trachea, It can be applied to reconstruction of the biliary tract, ureter and urethra.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an artificial blood vessel of the present invention.

FIG. 2 is a schematic view showing an example of a method for producing a reticulated tubular fluororesin body that is a constituent element of the present invention. FIG. 2-1 shows a tubular fluororesin body having a large number of cuts. Figure 2
Reference numeral -2 shows a state in which the tubular fluororesin body of FIG. 2-1 is pulled in the long axis direction to open the notches to form a net shape.

FIG. 3 is an enlarged cross-sectional view of a portion A (cross section) surrounded by a dotted line in FIG. FIG. 3-1 shows a state before heat treatment in Examples 3 and 4, and FIG. 3-2 shows a process in which the tubular fluororesin body of the outer layer becomes uneven due to heat from the outside to form a network structure. 3-3 shows a cross section of the completed product of the present invention.

[Explanation of symbols]

1 Tubular PTFE porous body 2 Reticulated tubular fluororesin body 3 Reticulated tubular fluororesin body's reticulated structure connection part (or convex portion) 4 Reticulated tubular fluororesin body reticulated structure hole (or recess) 5 Tubular fluororesin body Cut line to be inserted 6 Stretching direction for opening the cut 7 PTFE fiber 8 Nodule 9 Tubular fluororesin body before heat treatment 10 Thermal energy from the outer surface

Claims (5)

[Claims] 1. An artificial blood vessel composed of a tubular tetrafluoroethylene resin porous body having a fine fibrous tissue composed of fibers and nodules connected to each other by the tubular tetrafluoroethylene resin porous body. An artificial blood vessel characterized in that a coating layer of a tubular fluororesin body having mesh-like holes is provided on the outer surface of the body. 2. (1) Along the circumference of the tubular fluororesin body,
Along with the group of notches [A] in which the notches of the same length are arranged at equal intervals within the range of 2 to 4, along the other circumference at a position separated from the circumference by a certain distance, A group of cuts [B] in which cuts having the same length and the same number are arranged at positions shifted by an angle obtained by dividing 180 degrees by the number of cuts are alternately arranged along the long axis direction of the tubular fluororesin body. A tubular fluororesin body having a structure in which a large number are arranged at equal intervals is prepared, and then (2) the tubular fluororesin body has a fine fibrous structure composed of fibers and nodules interconnected by the fibers. The outer surface of the tubular tetrafluoroethylene resin porous body is covered by covering the outer surface of the porous ethylene resin porous body and pulling in the long axis direction to open the notches to form a mesh-like hole and reduce the diameter. Close to
Then, (3) heating at a temperature equal to or higher than the melting point of the fluororesin forming the tubular fluororesin body to form a coating layer of the tubular fluororesin body having mesh-like pores on the outer surface of the tubular tetrafluoroethylene resin porous body. A method for producing an artificial blood vessel, characterized in that 3. (1) A mixture of a non-sintered powder of a high molecular weight tetrafluoroethylene resin and a liquid lubricant, and a mixture of a low-molecular weight unsintered powder of a tetrafluoroethylene resin and a liquid lubricant. Co-extruded to form a laminated tube consisting of an inner layer containing a high molecular weight tetrafluoroethylene resin and an outer layer containing a low molecular weight tetrafluoroethylene resin, and (2) removing the liquid lubricant from the laminated tube. (3) a laminated tubular tetrafluoroethylene resin porous body having a fine fibrous structure consisting of fibers and nodules connected to each other by stretching in at least one axial direction without removing or When the obtained laminated tubular tetrafluoroethylene resin porous body is heat-sintered in a heat shrinkage-preventive state, or after heat-sintering, at least the outer layer is heated to a temperature of about 327 ° C. or more to form fine fibers in the outer layer. Cutting of tissue A method for producing an artificial blood vessel, which comprises forming a coating layer having a mesh-like hole by providing a portion that has been contracted and / or decomposed and removed. 4. A tubular tetrafluoroethylene resin porous body (a) having a fine fibrous structure composed of fibers and nodules connected to each other by the tetrafluoride forming the porous body (a). Prepared by using a tetrafluoroethylene resin having a lower molecular weight than that of a fluorinated ethylene resin, and coated with a tubular tetrafluorinated ethylene resin porous body (b) having a similar fine fibrous structure, and then at least the porous body ( A coating layer having reticulated pores by heating b) to a temperature of about 327 ° C. or higher to provide the porous body (b) with a portion where fine fibrous tissue is cut / contracted and / or decomposed and removed. A method for producing an artificial blood vessel, which comprises: 5. A tubular tetrafluoroethylene resin porous body (a) having a fine fibrous tissue composed of fibers and nodules connected to each other is previously cut and shrunk on the outer surface thereof. And / or coating with a similar tubular tetrafluoroethylene resin porous body (b) having a portion that has been decomposed and removed, and then at least the porous body (b) is about 327 ° C.
By heating to the above temperature and providing a portion where the fine fibrous tissue is cut / contracted and / or decomposed and removed over the entire surface from the outer surface to the inner surface of the porous body (b), a coating having mesh-like holes A method for producing an artificial blood vessel, which comprises forming a layer.