JPH0523362A - Preparation of artificial blood vessel - Google Patents

Abstract

PURPOSE:To provide an artificial blood vessel which can improve open rate of an artificial blood vessel with a small diameter wherein obstruction often occurs clinically after implantation and improvement thereof is required for practice in use and has large advantages such as being used without complicated procedures before operation for improving open rate such as incorporation of heparin and implantation of cultivated endothelial cells. CONSTITUTION:A seamless tube with a small diameter is obtd. by hollow weaving using a multifilament, consisting of a polyester ultrafine fiber as a warp and a weft. Bellows treatment (it is also called crimp treatment) of this seamless tube is performed and before or after this bellows treatment, alkali treatment for wt. reduction treatment is performed so as to make the rate of wt. reduction 10-60% to obtain an artificial blood vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an artificial blood vessel having a high patency rate using a multifilament yarn composed of ultrafine fibers.

[0002]

2. Description of the Related Art As an artificial blood vessel, various materials and various manufacturing methods have been proposed so far, but in view of biological reaction and durability, (a) an artificial blood vessel made of a polytetrafluoroethylene film, (B) Two types of artificial blood vessels, which are polyester woven or knitted fabrics, are considered to be practical.

Among these, as a method for producing an artificial blood vessel made of a polyester woven fabric belonging to (B), a flat woven fabric obtained by plain weaving is formed into a tube by sewing, adhering or fusing, or a tube having a plain weave structure is formed by an annular loom. A method of obtaining all at once has been proposed.

For example, Japanese Patent Laid-Open No. 57-11650 discloses an embodiment in which a tube having a plain weave structure is obtained by an annular loom. Japanese Unexamined Patent Publication (Kokai) No. 60-36058 discloses an artificial blood vessel in which a tubular object made of a plain fabric is heat-shrinked to reduce the diameter. Japanese Unexamined Patent Publication (Kokai) No. 60-190966 discloses a highly porous double velor type artificial blood vessel made of polyester fiber.

Japanese Patent Application Laid-Open No. 59-225020 discloses that
An artificial blood vessel in which ultrafine fibers of 0.5 denier or less are used in at least a part of the inner wall is shown, and in the example, a tube is formed by using a multifilament yarn in which the island component is polyethylene terephthalate and the sea component is a composite fiber of polystyrene. It is woven into a shape and then immersed in trichloroethylene to remove the polystyrene, thereby making it ultrafine.

Example 4 of JP-A-61-45765
Shows an artificial blood vessel in which a tube is woven by plain weaving of polyester fiber and a bellows processing is performed on the tube. Japanese Unexamined Patent Publication No. 61-45766 discloses an artificial blood vessel made of a knitted fabric of fibers composed of monofilaments of 1.0 denier or less (for example, 0.8d, 0.6d, 0.3d, 0.1d). There is also disclosure about processing. JP-A-61-45
Japanese Patent No. 767 discloses an artificial blood vessel in which a fiber knitted fabric tube is subjected to bellows processing, and synthetic resin filaments or filaments having elasticity are arranged along the valleys of the bellows processing. An example using ultrafine fibers having a denier or less (for example, 0.6d, 0.3d, 0.1d) is also given.

Japanese Laid-Open Patent Publication No. 60-77764 discloses a knitted and woven fabric having a multiple structure and having an inner wall and / or an outer wall.
An artificial blood vessel is shown which has at least a portion of ultrafine fibers of 0.5 denier or less (preferably 0.2 denier or less), and the ground yarn constituting the ground structure is mainly 1.0 denier or more. The ultrathinning is performed, for example, by removing one component of the multicomponent fiber.

In Japanese Patent Laid-Open No. 61-92666, polyester multifilament yarns are used as warp and weft (back yarn), and a polymer array fiber in which the island component is polyester and the sea component is polystyrene is used as the weft surface yarn. An artificial blood vessel is shown which is used by weaving it into a tubular shape with a double weave texture and then removing polystyrene to make it ultrafine.

[0009]

An artificial blood vessel made of polyester woven or knitted fabric has a limitation that it has a poor patency rate when used for revascularization of small diameter arteries of 6 mm or less. Artificial blood vessels made of polytetrafluoroethylene membrane were evaluated to have excellent antithrombotic properties in the early stages, but as the number of cases of use increased, intimal thickening of the anastomosis site occurred and good long-term patency was achieved. It turns out that there isn't.

Therefore, at present, the autologous vein graft is the only substitute blood vessel that can be reliably used for reconstructing an artery having a diameter of about 4 mm or less. However, there are many cases where one's own vein cannot withstand use, and the range of veins that can be collected is limited, such as the great saphenous vein. Even with autologous veins, long-term patency results are not always satisfactory.

With the aging of the Japanese population, the number of cases of AC bypass of the heart and revascularization of the lower limbs is increasing, and the emergence of a small-diameter artificial blood vessel with a high patency rate is clinically desired. There is a situation.

Up to now, attempts have been made to improve the patency rate by operations such as adding sustained-release heparin to ready-made artificial blood vessels or transplanting cultured endothelial cells, but it has also been clinically tried. I haven't gone by. Also,
It is not suitable for an emergency because it requires operations such as adding sustained-release heparin or planting cultured endothelial cells, and a considerable amount of time and equipment.

The artificial blood vessel produced by using the ultrafine fibers quoted above is expected to give good results as compared with an artificial blood vessel using a fiber of ordinary thickness, but the patency rate In terms of, there is still room for improvement in practical application.

The present invention can significantly improve the patency rate of a small-diameter artificial blood vessel, which is clinically sought to be improved in its use because of its large number of occlusions after transplantation. The object of the present invention is to provide a method for producing an artificial blood vessel, which has a great advantage that it can be used without complicated preoperative operations for improving the patency rate such as transplanting endothelial cells. .

[0015]

The method for producing an artificial blood vessel of the present invention is a bellows processed product of a seamless tube obtained by bag-weaving multifilament yarns made of polyester ultrafine fibers as warp and weft. Then, the reduction treatment is performed by performing alkali treatment before or after the bellows treatment.

The present invention will be described in detail below.

In the present invention, multifilament yarns made of polyester ultrafine fibers are used as warps and wefts for weaving.

The fineness of the ultrafine fibers is 1 d / f or less, preferably 0.5 d / f or less, and further 0.2 d / f or less. If the fineness exceeds the allowable value and becomes thicker, the patency decreases. Like Polyester ultrafine fibers are produced, for example, by the sea component melting method of polymer inter-array fibers,
At present, polyester ultrafine fibers are commercially available from several companies, and it can be used.

The thickness of the multifilament yarn is not limited, but is 20 to 180 denier, especially 30 to
It is often 140 denier, and the thickness of the warp and the weft can be different. In addition, depending on the case, it is possible to jointly use the ultrafine fibers and other fibers having a normal thickness. The above-mentioned multifilament yarn is usually subjected to text rise.

As a weaving method, a bag weaving method, which is a kind of double weaving method, is adopted. Here, the double-weave method is a method in which the warp yarns are arranged in the front warp yarns and the back warp yarns, and one weft yarn is reciprocated twice to form one ring while sequentially forming a tubular shape. This is a weaving method in which knotting is performed only at both ends. Normally, a plain weave is used, but a twill weave or another weave design may be used.

The seamless tube obtained as described above is subjected to bellows processing in order to adjust the length of implantation and prevent a kink phenomenon during use. Here, the bellows processing (also referred to as crimp processing) means that the tubular tube wall has an independent peak-valley structure or a spiral peak-valley structure. The bellows processing is typically performed by fitting a seamless tube onto a grooved rod or a grooved cylinder while winding a wire around the groove to form an independent or spiral mountain-valley structure. This can be achieved by heat setting in the state and fixing the peak-valley structure. At that time, a ring-shaped or spiral-shaped linear strip having elasticity may be arranged inside or outside the peaks or valleys of the peak-valley structure of the bellows processed product for reinforcement. Depending on the case, the bellows can be formed simultaneously with weaving by devising a bag-weaving method.

The caliber of the tube after the bellows processing can be arbitrarily set and is usually 2 to 30 mm, but it is also possible to make it smaller or larger. In particular, one of the advantages of the present invention is that an artificial blood vessel having a small diameter in a clinical use range of 2 to 10 mm can be prepared.

In the present invention, the seamless tube is contacted with the alkaline aqueous solution before or after the bellows processing to carry out the weight reduction processing. As a result, the fibers are thin and pliable, and the surface of the fibers has a fine rough surface that is more compatible with blood contact.

This weight reduction processing is performed before the bellows processing, that is, at the stage of a raw material (kibata) after bag-weaving and after the scouring.
It may be carried out at any stage of heat setting after scouring and stage after bellows processing.

As the alkali, sodium hydroxide, potassium hydroxide, sodium carbonate or the like is used, and the concentration of the alkali in the aqueous alkali solution is set to about 1 to 20%, preferably about 2 to 15%. The treatment temperature is about 80 ° C. or higher, usually 85 ° C. to the boiling point, and the treatment time is often about 5 minutes to 2 hours. The degree of weight loss can be controlled by appropriately setting the alkali concentration, the treatment temperature, and the treatment time.

The weight loss rate by this alkali treatment is 10-6.
It is desirable to set it to 0%, especially 15 to 55%, especially 20 to 50%. When the weight loss rate is too low, the purpose of improving the patency rate cannot be achieved, while when the weight loss rate is too high, the fiber is The strength may be reduced and blood may leak excessively from the tube wall.

[0027]

[Function] When the bellows processed product of the seamless tube is subjected to the alkali treatment before or after the bellows processing, the polyester ultrafine fibers are gradually dissolved from the surface layer and the fibers become thin, and the fiber gap of the woven fabric increases. It becomes bulky, and the contact pressure between threads decreases and it becomes supple. Then, the surface of the fiber has a fine rough surface which is more compatible with blood contact.

The tube in such a state can be used as an artificial blood vessel as it is without performing complicated preoperative operations such as adding sustained-release heparin or implanting cultured endothelial cells. It has an excellent patency rate.

[0029]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, "%" means% by weight.

Example 1 <Manufacture of artificial blood vessel> 1 made of ultrafine polyester fiber
Using 10 denier and 60 denier multifilament yarns, using 60 denier as warp yarn and 110 denier as weft yarn, a 4 mm diameter seamless tube was woven by the bag weaving method, scoured, and heat set.

The seamless tube obtained above was treated at a temperature of 9 with an aqueous solution of sodium hydroxide having a concentration of 80 g / liter.
The sample was immersed in a treatment bath at 0 ° C. for 18 minutes or 22 minutes and lightly stirred to carry out alkali weight reduction processing. As a result, weight-reduced products with weight reduction rates of 28.0% and 36.8% were obtained.
Observation with a scanning electron microscope confirmed that the fibers were clearly thin. Comparing the two types of weight loss products, the larger the weight loss rate, the thinner the wall (0.
08mm), and the texture was supple. Tensile strength is the weight loss rate
It was 4.6 kg / cm ² in the case of 36.8%, and had sufficient physical properties as compared with the small-diameter artery of a living body.

A wire was wound and heat set while the obtained tube was fitted onto a grooved rod. This makes the caliber
Since a 3.2 mm bellows processed product was obtained, it was fused and used for the required length.

<Transplantation Experiments and Results> The above artificial blood vessels of 3 to 4 cm in length were implanted into the femoral artery of a mongrel dog having a body weight of 12 ± 1 kg by end-to-end anastomosis. There was no resistance as the needle passed, and no bleeding from the needle hole was observed. As for transplantation, 4 animals and 8 limbs without alkali weight reduction processing and 2 animals with weight loss rate of 28.0% 2
The limbs were transplanted with a weight loss of 36.8% into 5 limbs.

36.8% of the most weight-loss graft
However, no blood leakage was observed after only one preclotting. Note that pre-clotting is generally performed three times or more. After transplantation, it was observed that the supple vessel wall pulsates with the arterial blood flow.

Two weeks to 1.5 months after the transplantation, the transplanted dogs were sacrificed. Regarding the transplantation results, patency was obtained in 2 out of 8 limbs without weight reduction processing, and patency was obtained in 1 out of 2 limbs with 28.0% reduction.
With 36.8% weight loss, patency was obtained in 6 out of 8 limbs (75%), and in both occluded limbs, thrombus was formed in the central anastomosis. When an open patent blood vessel was opened, some blood clots were found on the inner surface with the naked eye, but an intima with visible fibrous structure was observed over the entire length. In the findings of the tissue specimen,
Host cells were less likely to enter between the polyester fiber bundles, and an inner membrane with an unfinished portion was formed on the inner surface.

[0036]

In the method of the present invention, polyester ultrafine fibers, which are finer than the fibers used in ready-made artificial blood vessels, are used, and the fibers are further weight-reduced by alkali treatment. Therefore, the ultrafine fibers constituting the artificial blood vessel wall are further thinned and the tube wall is thin and supple. As a result, the antithrombogenicity of the inner surface structure is enhanced and the patency rate is improved. In addition, since it can be used directly without performing operations such as adding sustained-release heparin or transplanting cultured endothelial cells, it can be used in an emergency and can be used in general hospitals. There are also advantages.

As described above, according to the present invention, it is possible to reconstruct an arterial circulation having a small diameter, which has been difficult in the past, and the present invention is extremely significant.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Kitamura             5-30 Izumihoncho, Kanazawa City, Ishikawa Prefecture (72) Inventor Kiyofumi Sasaki             1-57-11 Mitsufuji, Musashimurayama-shi, Tokyo

Claims (2)

[Claims] 1. A bellows processed product of a seamless tube obtained by bag-weaving a multifilament yarn made of polyester ultrafine fibers as warp and weft, which is subjected to alkali treatment before or after the bellows processing. A method for producing an artificial blood vessel, which is characterized in that the weight is reduced by. 2. The weight loss rate by alkali treatment is 10 to 60%.
The method according to claim 1, wherein