JPS62343A - Fluorocarbon resin type artificial blood vessel and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an artificial blood vessel made of a fluorine-containing synthetic polymer.

[Summary of the invention]

The present invention features synthetic resin artificial blood vessels that can be bent with a small radius of curvature without the kinking phenomenon (the phenomenon of breaking when bent) by arranging mesh-like protrusions integrally formed on the outer wall surface of the artificial blood vessel tube. The purpose of this invention is to obtain an artificial blood vessel with high burst strength and excellent long-term patency.

Further, the present invention provides the method for manufacturing an artificial blood vessel, comprising: providing a large number of discontinuous cuts in the outer wall of the tubular molded product;
By stretching a tubular molded product in its length direction, it is possible to manufacture an artificial blood vessel extremely easily and at low cost.

[Conventional technology]

Currently, as artificial blood vessels, artificial blood vessels made of knitted fabrics of polyester fibers and artificial blood vessels made of fluororesin are mainly used. Polyester-based artificial blood vessels are made of fibers with a chemical structure of polyethylene terephthalate, and are crimped in a bellows shape to prevent kinking. On the other hand, fluororesin-based artificial blood vessels are made of polytetrafluoroethylene, which is hot-stretched to fibrillate (group small fibers) the blood contact surface.

[Problem that the invention seeks to solve]

It is known that fluororesin-based artificial blood vessels have superior long-term patency than polyester-based artificial blood vessels, and are significantly superior to polyester-based artificial blood vessels, especially when the diameter of the artificial blood vessel becomes small. However, it also has major drawbacks. It fibrillates the blood-contacting surface to aid the proliferation of endothelial cells after transplantation, but for this purpose, the tube is stretched in the length direction during manufacturing, and this stretching inevitably stretches the molecules. direction. For this reason, fissures tend to form along the stretching direction, that is, along the length of the artificial blood vessel. In actual experimental tests and in practical use, rupture occurs along the length of the artificial blood vessel, or part of the artificial blood vessel swells, just like an aneurysm.
This expanded portion is extremely susceptible to tearing. This phenomenon corresponds to the occurrence of varicose veins and aneurysms in the human body, and it is extremely important to overcome these drawbacks in practical use.

Conventionally, in order to prevent this phenomenon with artificial blood vessels made of fluororesin, tape-like tapes of the same type, which are stretched separately, are wrapped around the artificial blood vessel substantially at right angles to the length direction of the fluororesin artificial blood vessel. In this way, strategies have been taken to construct the artificial blood vessel wall from two layers, one in the longitudinal direction and the other in two layers oriented substantially at right angles to the longitudinal direction.

Alternatively, in order to prevent the molecules from being oriented in the length direction and easily tearing along the longitudinal direction (the length direction of the artificial blood vessel), for example, polypropylene threads can be spirally wrapped around the outer periphery of the artificial blood vessel. Some attempts have been made to achieve this goal by wrapping the fluororesin-based artificial blood vessel around the arterial system, but these methods still provide sufficient security for the use of fluororesin-based artificial blood vessels in the arterial system, which is under pressure. These methods have many problems, such as complicated processes, labor, cost, and time, many quality control problems, and high costs. This phenomenon (called the kinking phenomenon) occurs easily when an artificial blood vessel is used as a substitute for a peripheral blood vessel when the knee or elbow is bent. The appearance of is strong (requested).

[Means for solving problems]

In order to solve the problems presented above, the present inventor investigated from a structural perspective and tried to improve a fluororesin-based artificial blood vessel with a new idea.As a result of various attempts, the present inventor has developed the present invention. completed.

The gist of the present invention is to provide an artificial blood vessel made by stretching a tubular fluorine-containing polymer, in which an integrally molded plate-like mesh projection is disposed on the outer wall surface of the artificial blood vessel tube. This is an artificial blood vessel, and the manufacturing method thereof is to provide a large number of discontinuous cuts in a circular or spiral shape on the outer wall surface of a tube-shaped molded product made of a fluorine-containing polymer 1, and to make a number of discontinuous cuts adjacent to each other. The tubular molded product is stretched in the length direction between the cuts, with a discontinuous part of any cut being positioned with respect to a continuous part of an adjacent cut. I'll do it.

After stretching, the discontinuous portions of these cuts become nodules of the mesh-like protrusions. The number of discontinuous parts is 2 or more and 50 or less, preferably 3 or more and 20 or less while the cut goes around the outer wall of the artificial blood vessel.

If the number of discontinuous parts, that is, the number of nodules in the network, is too small, bursting strength cannot be maintained, and if there are too many, the artificial blood vessel has poor elasticity and becomes difficult to bend.

A perspective view and a sectional view of the artificial blood vessel of the present invention are shown in FIGS. 1A and 1B, respectively, and a partially enlarged view of the mesh-like protrusion 3 in these figures is shown in FIG. 2.

In addition, in FIG. 1B and FIG. 2, each character symbol in the figure has the following meaning. Note that, for example, in the case of h, the average value is represented by T, and the other average values also follow this.

h: height of mesh-like protrusion 3) W: half-width of mesh-like protrusion 3 (protrusion 3 at height of 1/2h)
width (Illllll) d: Thickness of the artificial blood vessel (S) 1: Inner diameter of the artificial blood vessel (Tsuru) D-: Distance between W4 eyes (tm) r: Minimum radius of curvature that can be bent without kinking ( n) lo Maximum width (mm) of the mesh portion 10 surrounded by the two sets of mesh-like protrusions 3 in the longitudinal direction of the artificial blood vessel 1: Length of the mesh portion 10 in the direction perpendicular to the length direction of the artificial blood vessel 1≦7≦2 h between the average height (h) and the average half-width (width at the height of 1/2 h) of the mesh-like protrusions 3 of the present invention
(1) There is a relationship between the wall thickness (d) of the artificial blood vessel and the average half-width of the mesh-like projections 3 (
There is a relationship of 0, ld5w≦IOd (2),
Average maximum width T of the mesh-like projection 3 in the length direction of the artificial blood vessel
7 and the average length T in the direction perpendicular to the length direction of the mesh artificial blood vessel
, the ratio of 1.0≦7. /I7≦50 (3) Preferably.

Cough 7 It is true that when the artificial blood vessel satisfies the relationships of the above equations (1), (2), and (3), the artificial blood vessel exhibits extremely kinking resistance against bending and has strong breaking strength. The inventor discovered this. If the ratio It, /T7 is smaller than the range expressed by the above equation (3), there will be no bending flexibility and the material will not bend. Furthermore, if the ffi,/T7 ratio exceeds 50, it lacks elasticity and cannot be bent. Therefore, the condition of the above equation (3) is required, and if this condition is satisfied, it can be easily bent to a steep angle.

The above formula (1) is more preferably □　≦W≦h　　　　(1) and The above formula (2) is more preferably 0.3 d≦ma≦5d (2) and The above formula (3) is more preferably, 1.0≦I! , /l, ≦30 (3).

In addition, it is easier to anastomose and suture an artificial blood vessel during surgery when the artificial blood vessel wall is thinner, and long-term patency is determined by the quality of the suture finish.
It is very important that it is easy to suture. The ease of anastomosis and suturing is determined by the thickness of the artificial blood vessel, and the thinner the wall, the more suitable for anastomosis and suturing.

However, as it becomes thinner, its bursting strength becomes weaker, exposing its shortcomings. Therefore, as shown in equations (1) and (2) above, the wall thickness d
When the average half-width 7 and the average height T of the mesh-like protrusions are defined, the bursting strength is sufficient, the sutureability and anastomosis are excellent,
Moreover, it can be bent with a small radius of curvature without kinking.The present invention provides a new artificial blood vessel that has excellent mechanical performance and can be bent with an extremely small radius of roundness without kinking. Expressed in another way, the invention defines the number of mesh-like projections within a certain range with respect to the diameter of the artificial blood vessel, regulates the cross-sectional width of the mesh-like projections within a certain range with respect to the wall thickness of the artificial blood vessel, and They discovered that if the height of the rope-like protrusions is controlled within a certain range, an artificial blood vessel with strong bursting strength and that can be bent into sharp curves without kinking can be obtained.

FIG. 3 is a front view showing the artificial blood vessel of the present invention in a bent state.

According to the invention, the inner diameter I! , fl artificial blood vessel,
The radius of curvature rn of the center line 11 of the artificial blood vessel is r≦1.51
Below, further 1. It is possible to bend the wire to 0.81 or less, and even to 0.81 or less without kinking. This is because by configuring the artificial blood vessel as shown in the present invention, each part of the artificial blood vessel can expand and contract with a considerable degree of freedom.
This is because the outer side (furthest from the center of bending, that is, the center of curvature) can be extended. In addition, the rupture strength of the artificial blood vessel of the present invention is strong, and the strength is (d+T
) thickness is comparable to the bursting strength.

In addition, in order to be able to bend with a small radius of curvature without kinking, the artificial blood vessel must have elasticity, and the natural length (Lo) in the unloaded state and when compressed in the length direction of the artificial blood vessel are required. The length between ) is 0.1 r, ≦L2≦0.7L+1, preferably 0.2L, ≦LP ≦0.5L.

Therefore, it is necessary that the artificial blood vessel is compressible.
The present invention provides such an artificial blood vessel (see Figures 4A and 4B).

In order to provide such properties, the average half-width 7 and the average spacing between adjacent mesh protrusions are set to the relationship 0.37≦-b-≦157 in Fig. 1B. It becomes possible.

LP is 0. Compression to below lLo cannot be achieved unless the wall thickness of the artificial blood vessel is made abnormally thin.
The bursting strength of the artificial blood vessel is so low that it cannot be put to practical use.

Moreover, if LP is 0.7 t,o or more, it is impossible to bend the material with a small curvature without kinking. Being able to bend without kinking is a very important performance.
This solves the problem that existed until now when kinking occurs, blood stagnates there and immediately coagulates.

It must be noted that the mesh-like protrusion 3 of the present invention evenly covers the exterior 2 of the artificial blood vessel, and its shape is such that it can easily expand and contract in the length direction of the artificial blood vessel. .

That is, the mesh is smoothly continuous in the direction perpendicular to the length direction of the artificial blood vessel, while forming alternating sharp angles in the length direction of the artificial blood vessel. It has extremely high morphological stability in the circumferential direction of blood vessels, and is characterized by not deforming even under considerable stress.

That is, the artificial blood vessel of the present invention is a blood vessel that can be easily expanded and contracted in the length direction, and has excellent morphological stability and does not deform in the direction perpendicular to the length direction. This is largely due to the shape of the mesh-like projections that are integrally arranged on this artificial blood vessel.

As will be described later in Examples, the artificial blood vessel of the present invention can be easily manufactured using a fluororesin by appropriately changing the molding conditions.

The fluororesin used in the present invention is most preferably polytetrafluoroethylene, and other substances such as acrylic resin or polyurethane may be added for the purpose of modification. Also, polytetrafluoroethylene copolymers, such as tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymers,
Ethylene tetrafluoride - ethylene copolymer, ethylene tetrafluoride -
Propylene copolymers, trifluoroethylene chloride, and vinylidene fluoride may also be used.

The manufacturing process of the artificial blood vessel of the present invention will be explained with reference to FIG. In the artificial blood vessel of the present invention, as shown in FIG. 5(a), a tube-shaped molded product 4 made of a fluorinated resin is provided with independent ring-shaped or spiral-shaped discontinuous cuts 5 in the tube. The discontinuous portion 9 is provided on the outer wall surface 8 so that the continuous portions of the cuts 5 on both sides are located, and the tube-shaped molded product 4 is rapidly stretched in the length direction under appropriate conditions.

FIGS. 5(b) to 5(d) show the manner in which stretching is performed. In FIG. 5, the numerical values displayed in each part are based on Example 1 described later.

When the tubular molded product 4 is stretched, the inner wall side of the tube is stretched almost uniformly. On the other hand, since there is a cut 5 on the outer wall side, no force acts on either side of the cut 5. Stress is concentrated exactly at the end B of the cut and this part is stretched, but the force applied to the bottom A of the cut in Figure 5(b) is weak, and ultimately ), the part at the end B of the cut is stretched at a high magnification, and then passes through the stretched part B and then into the highly stretched part B2.
is formed, and the bottom part A of the cut becomes a low stretch part AI.

And the protruding portion C4 in FIGS. 5(b) to (d); l
! E-stretching stress does not work, so there is no substantial stretching.

FIG. 6 shows the process of forming the mesh protrusions 3 and the mesh portions 10 in a partial external view. From this figure, it can be seen that the discontinuous part 9 of the cut 5 before the drawing process becomes the knot part 12 of the rope section 10 after the drawing process.

Therefore, to put it another way, the artificial blood vessel according to the present invention is an artificial blood vessel made by stretching a tube-shaped fluorine-containing polymer, in which an integrally formed mesh-like plate-like protrusion is formed on the outside of the artificial blood vessel. The inner wall surface 7 and outer wall surface 2 of the tube are fibrillated by stretching, and the state of the fibrils between the mesh-like protrusions 3 on the outer wall surface 2 is better than that of the fibrils on the inner wall surface 7. They also form loose fibrils.

In other words, the present invention relates to an artificial blood vessel made by stretching a tube-shaped fluorine-containing polymer, in which the integrally molded plate-like mesh protrusion 3 is attached to the outer wall surface of the artificial blood vessel. The high extension part B, ( sparse fibril surface)
It can be said that this is an artificial blood vessel in which low elongation parts (dense fibril parts (the part indicated by the dotted line 1 in FIG. 5(d))) alternately exist.

Alternatively, an artificial blood vessel as described above, in which the condition of the fibrils on the inner wall surface is relatively uniform, and the condition of the fibrils on the outer wall surface (including the virtual outer wall surface ■) is non-uniform in the length direction of the artificial blood vessel. It can also be described as a blood vessel.

In any case, since the outer wall surface has a more sparse fibrillar surface, it is easy for endothelial cells to invade and grow from the outer wall surface, and the biogenization occurs in a short time, improving patency after transplantation. has made a major contribution.

[Effect]

By adding the means shown in the present invention to an artificial blood vessel, it is possible to provide an artificial blood vessel with new performance that is strong in bursting strength and can be bent with a small radius of curvature.
An artificial blood vessel made of synthetic resin with excellent long-term patency that can be used for arteries, etc. It is now possible to donate.

〔Example〕

The present invention will be explained in more detail with reference to Examples below.

(Example 1) 0.5 kg of commercially available tetrafluoroethylene resin (Teflon, manufactured by Mitsui Fluorochemical Co., Ltd.) and 1 extrusion aid (white oil (Sumoil P-55, manufactured by DuMatsu Oil Co., Ltd.) as a liquid lubricant)
30 cc were uniformly mixed in a tumbler, preformed under pressure, and then extruded into a tube shape using a ram extruder. The white oil was then heated at a temperature below its boiling point to thoroughly remove it. This tubular molded product has an inner diameter of 6fl and a wall thickness of 0.
．． There are 8 dragons.

Insert a stainless steel rod so that it is almost in close contact with the inner cavity of the tube, and while rotating the rod, make circular cuts at 0.2 mm intervals on the outer wall surface at right angles to the length of the tube. Ta. The depth of the cut is 0.1 mm from the inner wall of the tube.

This cut creates 4 discontinuous parts while going around the circumference,
The discontinuities of adjacent cuts are offset with respect to each other so that any discontinuity is located in the center of the continuous part of the cuts adjacent to it.

This tube is heated 1.2 times to 1 times at a temperature below 327℃.
It is stretched 0 times, but approximately 300°C is appropriate. In this example, a 20 cta tube was rapidly stretched to 100 cm while being heated to 280°C. By this treatment, the cut portions are strongly stretched, and since no force is applied to the portions between the cuts, they are not stretched, and the stretched portions have a high stretching ratio and have a sparse fibril structure.

On the other hand, the inner wall surface is uniformly stretched and becomes relatively fine and dense fibrils.

In this way, the outer wall surface of the tube comes to be covered with unstretched mesh plate-like protrusions by stretching twice.

Both ends of the stretched tube are fixed to prevent it from shrinking, a pipe for introducing cooling air is connected to one end of the tube, the other end is closed, and the temperature is raised to 320°C, when the temperature is 0.4
An air pressure of "kg/cm" was rapidly introduced, and while this pressure was maintained, the temperature was raised to 400° C., and then rapidly cooled to return to room temperature.

The completed artificial blood vessel has an outer wall shape as shown in Figures 2 and 4A, an inner diameter of 6 fins, and a wall thickness (d).
0.1 m, average height of mesh plate-like protrusions h) 0
．． 7 vs, average half width (-w) 0.2 tm, It
nllf is 7.5, the average distance (D) between protrusions in the longitudinal direction of the artificial blood vessel is 0.581 m, and LP/LO is 0.4
1. The minimum radius of curvature (r) was 6.4 fl.

(Example 2) White oil was removed from the tubular molded product extruded using the ram extruder in Example 1 by heating at a temperature below the boiling point of white oil. As in Example 1, a stainless steel rod was inserted into the tube-shaped lumen in this state so that it was in close contact with the inner cavity, and while rotating the stainless steel rod once, a cut was made on the outer wall surface of the tube using an ultrasonic cutter, and the tube was cut once. direction at a constant speed.

Five discontinuities were created while going around the notch.

In this way, we were able to make discontinuous spiral cuts.

The inner diameter of this tube is 10 mm, the thickness is 1.0 mm, and the slits are spaced at 0.12 mm intervals, leaving 0.2 fins from the inner wall surface of the tube in a spiral shape. Next, this tube was heated to 290° C. and rapidly stretched 3.5 times. By this method, a polytetrafluoroethylene artificial blood vessel having a mesh-like plate-like protrusion on the outer wall layer was created. The fibrils on the inner wall surface are fine, with an average length of 32 μm and an average spacing between fibrils of 2.8 μm.On the other hand, the average length of fibrils between protrusions on the outer wall layer is 0.3 tll, and the average length between the fibrils is 2.8 μm. The average interval was 6 Q ttm.

The morphological characteristics of this artificial blood vessel (see Example 1 and the text for symbols) are: ! =10fi, d =0.2 crane, h =0.6 crane,
Ma = 0.1 us, D ”0.4411m, L P
/ Lo = 0.51, r = 18 + u, end, /i
! , =9.211fi? there were.

(Examples 3 to 6) In the same manner as in Example 1, several types of artificial blood vessels with inner diameters shown in the table below were made.

In the table below, the compression ratio t, P/LO, and the minimum radius of curvature r at which kinking does not occur are also entered.

Example Inner diameter 11 w IJTHd D
LP/LOr(■-) 3 3 0.5 0.1 8 0.2 0.35
0.30 4.84 6 0.8 0.1 1!
0.3 0.25 0.47 7.05 10
1.0 0.2 13 0.4 0.36 0.4
9 14.16 15 1.0 0.2 15 0
．． 6 0.48 0.31 17.8 Unit: Dragon (Example 7) A pressure of 800 Tsuru ng was applied intermittently to the artificial blood vessels of Examples 1, 2, and 4.6 at a rate of 10 times/min for 30 days. However, no rupture phenomenon was observed.

〔Effect of the invention〕

The present invention provides an artificial blood vessel made of fluororesin-based synthetic resin, which has high bursting strength and can be used as an arterial blood vessel, yet has a small radius of curvature and can be bent without kinking, and can be used as a peripheral blood vessel substitute. It has now become possible to provide artificial blood vessels with excellent long-term patency. Moreover, the manufacturing method is extremely simple, leading to cost reduction.

[Brief explanation of drawings]

FIG. 1A is a perspective view showing an embodiment of the artificial blood vessel of the present invention;
Figure 1B is a longitudinal sectional view of the artificial blood vessel in Figure 1, Figure 2 is a partially enlarged view of the mesh-like protrusion, Figure 3 is a partial front view of the artificial blood vessel in Figure 1 in a bent state, and Figure 4A. 1 is a schematic front view of the artificial blood vessel shown in FIG. 1 in an unloaded state, FIG. 4B is a schematic front view of the artificial blood vessel shown in FIG. 4A in a compressed state, and FIG. 5 illustrates an embodiment of the method of the present invention. A perspective view showing the process for (
a), partial cross-sectional views (b) to (d), and Figures 6 (a) and (b).
) is a partial external view showing the formation of mesh-like protrusions. In addition, in the symbols used in the drawings, 2-...------111...-Outer wall layer 3--
・−1−−−・・・−・−Mesh-shaped projection 4−−−−−−−
−−−−−−−・−・−Tubular molded product 5−−
・−−−−−−・・−・− Cuts 7 to −−1−−−11−−−−−−m = Inner wall surface 8−・−・・−・・−
・−−−−−Outer wall surface 9−・−・−・・−−−−−−
---1.Discontinuous part 10-------1 mesh part 12------------ Knot part AI・
−−−−−1−−−・−・−Low stretch part B, −−−−−
−−−−−−−−One stretched portion B t =−−−−−−−−
-----・Highly stretched part c------------
−・−Unstretched portion■−・・−・−・−−−1−・・−Virtual outer wall surface.

Claims (1)

[Scope of Claims] 1. An artificial blood vessel made of a stretched fluorine-containing polymer, in which an integrally molded mesh projection is disposed on the outer wall surface of the artificial blood vessel tube. 2. A large number of discontinuous cuts are provided in the outer wall surface of a tubular molded product made of a fluorine-containing polymer in a ring shape or a spiral shape, and any discontinuous part of the cut is made between adjacent cuts. , a method for manufacturing an artificial blood vessel, comprising stretching the tubular molded product in its length direction so that the tubular molded product is positioned in relation to a continuous portion of the cut adjacent to the cut.