JPH04146745A - Tubular body for artificial vessel - Google Patents

Abstract

PURPOSE:To suppress the Pannus formation at an anastomosis part by arranging the first layer which possesses the extension performance and porosity and the second layer which possesses the extension/contraction performance and porosity, so that holes which communicate to the inside from the outside of the wall of the tubular body are provided. CONSTITUTION:A tubular body for artificial vessel is a tubular body consisting of the first layer which possesses the extension performance and porosity and is prepared from a fiber structural body which is formed from the fiber having the nonextension performance in the form of a braided article, knit article, or nonwoven fabric, and the second layer which is formed from the material having the extension performance and porosity. The fiber which constitutes the first layer is selected from among polyester resin, polyamide resin, etc. The material which constitutes the second layer is selected from among the polyester elastomer, polyolefin elastomer, diene elastomer, fluorinated elastomer, etc. The tubular body possesses the extension/contraction performance in 5-15% in the radial direction and 10-15% in the longer axis direction, and the fiber structural body has preferably 10-200 pieces of fiber bundles per inch. Further, the second layer preferably possesses a foamed article form, and the first layer is preferably possesses a bellows structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an artificial blood vessel having physical properties similar to those of a living blood vessel. More specifically, the present invention relates to an artificial blood vessel that is free from vanus hyperplasia at the anastomotic site during transplantation and has excellent safety.

(Prior Art and Problems) In recent years, along with advances in vascular surgery, research into artificial blood vessels has progressed, and a large number of artificial blood vessels have been developed. Such artificial blood vessels can be used, for example, if a patient's artery forms an aneurysm or
It is transplanted as a replacement when there is poor blood circulation due to thickening of the intima or when various disorders occur in various organs. Artificial blood vessels currently used for boat fishing include those made from knitted or woven polyester fibers, and those made from porous expanded polytetrafluoroethylene (EPT).
FE) products are used.

These artificial blood vessels have holes that communicate from the inside to the outside of the blood vessel wall, and after being implanted in a living body, they are quickly covered with pseudoendothelium, and tissue can invade from the living tissue side through these holes. This allows the artificial blood vessel to be stably organized.

However, because the mechanical properties of these artificial blood vessels are significantly different from those of biological blood vessels, even if they remain patent in the early stage after transplantation, over a long period of time, the endothelial cells of the host blood vessels are difficult to spread and organize. Inconveniences occur, such as a significant delay in the process, and hyperplasia of vanus at the anastomotic site, which can cause thrombus.

As an artificial blood vessel whose mechanical properties approximate those of biological blood vessels,
In particular, an artificial blood vessel described in Japanese Unexamined Patent Publication No. 182959/1983 is known as one that approximates compliance. Compliance here refers to the ratio of changes in intravascular volume to changes in blood pressure, but simply approximating this compliance to that of a living body will not completely suppress pannus hyperplasia. Therefore, long-term patency was not possible.

The present inventor discovered the fact that this vanus hyperplasia is more likely to occur in areas where the transplanted artificial blood vessel is frequently constricted (i.e., bends or shrinks following the movement of the living body). Based on this knowledge, we diligently searched for mechanical properties that should most closely approximate those of biological blood vessels, and found that the elasticity of artificial blood vessels has a significant effect on pannus hyperplasia, especially at the anastomotic region. This is what completed the present invention.

In knitted and woven structures such as polyester fibers that have been used conventionally, it is possible to adjust the elasticity by reducing or expanding the pores between the fibers, If the fibers are made sparse), the fibers will stretch without limit, and if the fibers are made dense, the cell invasiveness will decrease and there is a risk that organization will be delayed. Therefore, it is very difficult to adjust the elasticity of the fiber structure to a desired degree, and therefore it is insufficient for practical use.

Therefore, the present invention aims to improve the elasticity of the fiber structure artificial blood vessel by changing its structure without impairing its biocompatibility (cell invasiveness), so that its elasticity approximates that of a living blood vessel, and therefore, at the time of implantation, the anastomosis The present invention relates to an artificial blood vessel that suppresses pannus hyperplasia and enables early organization.

(Means for Solving the Problems) The object is to provide a first layer having extensibility and porosity consisting of a fiber structure made of knitted, woven or non-woven fabrics made of non-stretchable fibers, and a first layer having extensibility and porosity. and a second layer made of a material, the first layer and the second layer being arranged so as to have holes that communicate with each other from the outside to the inside of the wall of the tubular body. This is achieved by the characteristic tubular body for artificial blood vessels.

The tubular body has a thickness of 5 to 15% in the radial direction and 10 to 15% in the longitudinal direction.
It is preferable that it has 50% elasticity.

Moreover, it is preferable that the number of fiber bundles per inch of the fiber structure is 10 to 200.

Further, it is preferable that the second layer has a foam shape.

Further, it is preferable that the first layer has a bellows structure.

The present invention will be explained in detail below.

Therefore, the tubular body for an artificial blood vessel according to the present invention includes a first layer having extensibility and porosity, which is made of a fiber structure made of knitted, woven or non-woven fabrics made of non-stretchable fibers, and extensibility and porosity. and a second layer formed of a material having the following properties, wherein the first layer and the second layer are arranged so as to have holes that communicate with each other from the outside to the inside of the wall of the tubular body. This is a characteristic feature.

The first layer is a layer that functions as a skeleton of the artificial blood vessel of the present invention. The fibers constituting this first layer are not particularly limited as long as they have a certain degree of strength and are non-stretchable, but at least one type of fiber selected from polyester resins, polyolefin resins, polystyrene resins, and polyamide resins can be used. It is preferable that the

Such fibers do not have elasticity or porosity per se, but are given porosity and elasticity by being formed into a fibrous structure such as knitting, woven fabric, or nonwoven fabric. .

The knitting method is not particularly limited, and can be produced using a knitting machine capable of horizontal knitting and warp knitting. As such a knitting machine, a Raschel knitting machine, a double Raschel knitting machine, etc. can be suitably used.

The weaving method is not particularly limited, and it can be produced using a loom capable of plain weaving, Sanada weaving, or other weaving.

The method for producing the nonwoven fabric is not particularly limited as long as it can produce a nonwoven fabric having porosity.

The fiber density of the fiber structure having such a shape can be set to a relatively low density due to the presence of the second layer described below. A specific fiber density is preferably 10 to 200 fibers per inch, more preferably 15 to 100 fibers per inch. If there are more than 20 fibers, the fiber structure will become too dense, impairing cell penetration during transplantation, while if it is less than 10 fibers, the fiber structure will become too sparse, resulting in blood leakage after transplantation. There is a risk.

The diameter of the fibers constituting the fiber structure is not particularly limited, but is 20 to 100 deniers, more preferably 50 deniers.
A material having a diameter of about 90 denier may be used.

In addition, in order to improve the elasticity of the fiber structure, it is preferable to provide the fiber structure with fine bellows (perform crimp processing).

The second layer has the function of supporting and reinforcing the first layer.

Due to the presence of this second layer, the artificial blood vessel according to the present invention has elasticity that is similar to that of a biological blood vessel without impairing the cell invasiveness of the first layer.

The material constituting the second layer is not particularly limited as long as it is blood compatible (i.e., has no risk of causing acute toxicity, inflammation, hemolysis, or exothermic reactions) and has elasticity, but polyester The material is preferably at least one selected from polyolefin-based elastomers, polystyrene-based elastomers, polyamide-based elastomers, ionomers, vinyl chloride-based elastomers, diene-based elastomers, and fluorine-based elastomers.

Such a material may be provided with porosity by being formed into a fibrous structure such as a knitted fabric, a woven fabric, a nonwoven fabric, etc., but it may be provided with porosity by being formed into a foam. is preferred.

Various known methods can be used to form the above-mentioned material into a foam, but according to the method of freeze-drying a resin solution and foaming, it can be formed by relatively easy conditions (temperature, pressure, etc.). This is preferable because the porosity can be adjusted. Note that this effective rate is determined by placing the above-mentioned first layer in combination with the desired water permeability (generally 30
00cm37cm2 or less).

The artificial blood vessel according to the present invention is formed by arranging the first layer and the second layer so as to have holes communicating substantially from the outside to the inside of the blood vessel wall.

The arrangement of the first layer and the second layer is: (1) placing the second layer on the inner surface of the first layer, (2) placing the second layer on the outside of the first layer, and (2) placing the second layer on both sides of the first layer. Possible configurations include arranging two layers, and (i) intruding the second layer between the fibers that make up the first layer, but it is arranged so that it has holes that communicate from the outside to the inside of the blood vessel wall. If so, it is not limited to these.

The artificial blood vessel of the present invention having such a structure has elasticity similar to that of a living blood vessel. The degree of elasticity varies depending on the thickness of the artificial blood vessel and the site of use, and cannot be specifically determined, but it is preferably 10 to 50% in the longitudinal direction and 5 to 15% in the radial direction. The elasticity may be adjusted by changing the structure or fiber density of the fibrous structure constituting the first layer, or by changing the elasticity of the material constituting the second layer.

In addition, elasticity in the present invention means the amount of change in length with respect to a constant change in internal pressure.

Furthermore, the inner surface of the artificial blood vessel of the present invention may be coated with a known antithrombotic substance such as heparin.

The artificial blood vessel of the present invention can also be used as a bypass tube, patch material, blood access, or the like.

Next, a method for manufacturing an artificial blood vessel according to the present invention will be explained.

First, a tubular knitted fabric is produced using non-stretchable fibers and the above-mentioned knitting machine.

The crimping process is then performed by inserting a mandrel into the lumen of the tubular body and, more preferably, by wrapping a thread around the outside of the tubular body. Next, a solution of a stretchable resin is prepared in a test tube, and the tubular body is immersed in the solution. continue,
Lyophilize the entire test tube and foam the resin. Thereafter, if necessary, the resin density can be increased by pressing with a mandrel, etc., to obtain the artificial blood vessel of the present invention.

Note that the tubular body may be formed of a woven fabric, a nonwoven fabric, or the like.

Next, the present invention will be explained in more detail by showing Examples and Comparative Examples.

[Examples and Comparative Examples] Using 75 tenier/36 filament polyethylene terephthalate yarn (manufactured by Toyobo Co., Ltd.), warp knitting was performed with a double Raschel knitting machine (manufactured by Karl Mayer) at a density of 20 stitches/inch, A tubular body with an inner diameter of 8II1 m was produced (comparative example). Subsequently, a stainless steel mandrel having an outer diameter of 3 mm was inserted into the obtained tubular body, and a thread was wound spirally around the outside of the tubular body to perform crimping. In this state, heat setting was performed by heating at 180° C. for 3 minutes. Next, the mandrel was removed from the tubular body, placed in a test tube with an inner diameter of 11 mm, and further placed in the lumen of the tubular body.
A stainless steel mandrel having an outer diameter of 7+I+ffl was placed in the center of the lumen of the tubular body. Next, the hardness is 5h
A polyester elastomer of are-D40 (manufactured by DuPont Toshi) was dissolved in chloroform to a concentration of 6%, and 1 part by weight of the resulting solution was mixed with 5 parts by weight of dioxane to prepare a solution. Next, the solution was poured into a test tube, filling the periphery of the tubular body. Next, the whole test tube was placed in the freezer in stages at -208C1-40℃ and -80℃ to gradually freeze it, then the mandrel was removed, the tubular body was removed from the test tube, and the pressure was reduced while it remained frozen. and lyophilized. After the freeze-drying is completed, the stainless steel mandrel with an outer diameter of 71 mm is inserted into the lumen of the tubular body again.
The tubular body was rolled on a flat plate to increase the density of the polyester elastomer porous body. In this way, the inner diameter 8
A tubular body for an artificial blood vessel with a diameter of 1 mm was prepared.

of the obtained tubular body from 50mmHg to 1100ff1l
Table 1 shows the expansion and contraction ratios with respect to pressure changes to nH.

(Hereinafter, blank spaces) Table 1 Furthermore, the obtained artificial blood vessels of Examples and Comparative Examples were cut into lengths of 5 cm, and pre-clotted using blood from a mongrel adult weighing 20 kg. Then, to the thoracic aorta of the same size,
The obtained artificial blood vessel was transplanted by anastomosing both ends. After 12 months, the dog was sacrificed, and the sample was extracted and observed.
The entire inner surface of the blood vessel was covered with a thin, shiny endothelium, and no hyperplasia of the intimal vanus was observed at the anastomotic site, which was covered with a fairly uniform intima. In contrast, in the artificial blood vessel of the comparative example, hyperplasia of the pannus was observed at the anastomosis, and adhesion of thrombus was observed at the anastomosis. Furthermore, it was observed that the expansion of endothelial cells also tended to be delayed compared to the artificial blood vessels of Examples.

(Effects of the Invention) The tubular body for an artificial blood vessel according to the present invention comprises: a first layer having extensibility and porosity made of a fiber structure made of knitted, woven or non-woven fabrics made of non-stretchable fibers; A tubular body comprising a second layer made of a porous material, the first layer and the second layer being arranged so as to have holes communicating from the outside to the inside of the wall of the tubular body. This feature allows the fiber structure artificial blood vessel to have elasticity similar to that of biological blood vessels without impairing its biocompatibility (cell invasiveness), thereby suppressing pannus hyperplasia at the anastomotic region during implantation. Moreover, it has the effect of making it possible to achieve organization at an early stage.

Claims (7)

[Claims] (1) A first layer having extensibility and porosity made of a fiber structure made of knitted, woven or non-woven fabrics made of non-stretchable fibers, and a second layer formed of a material having stretchability and porosity. A tubular body for an artificial blood vessel, comprising: the first layer and the second layer are arranged so as to have a hole that communicates from the outside to the inside of the wall of the tubular body. (2) The tubular body for an artificial blood vessel according to claim 1, wherein the tubular body has elasticity of 5 to 15% in the radial direction and 10 to 50% in the longitudinal direction. (3) The tubular body for an artificial blood vessel according to claim 1 or 2, wherein the fiber structure has 10 to 200 fiber bundles per inch. (4) The tubular body for an artificial blood vessel according to any one of claims 1 to 3, wherein the second layer has a foam shape. (5) The tubular body for an artificial blood vessel according to any one of claims 1 to 4, wherein the first layer has a bellows structure. (6) The material constituting the second layer is at least one selected from polyester elastomer, polyolefin elastomer, polystyrene elastomer, polyamide elastomer, ionomer, vinyl chloride elastomer, diene elastomer, and fluorine elastomer. The tubular body for an artificial blood vessel according to any one of claims 1 to 5. (7) The first layer is made of at least one material selected from polyester resin, polyolefin resin, polystyrene resin, and polyamide resin.
7. The tubular body for an artificial blood vessel according to any one of items 1 to 6.