JPS61293450A - Artificial blood vessel - 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 comprising a synthetic polymer, particularly a fluorine-containing synthetic polymer or polyurethane.

[Summary of the invention]

The present invention provides an artificial blood vessel made of synthetic resin, in which an annular projection is provided along the outer periphery of the artificial blood vessel tube, and a specific relationship is established between the average half-width of the annular projection and the average height of the annular projection. By specifying that the annular protrusion intertwines and integrates with adjacent annular protrusions while going around the artificial blood vessel to form a peripheral protrusion,
The purpose is to obtain an artificial blood vessel that can be bent without the kinking phenomenon (a phenomenon of breaking when bent), has high bursting strength, and has excellent long-term patency.

[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.
It is used with a bellows-shaped crimp to prevent the kinking phenomenon. On the other hand, fluororesin-based artificial blood vessels are made of polytetrafluoroethylene, which is hot-stretched to fibrillate the blood-contacting surface (fine fiber clusters).

[Problem that the invention seeks to solve]

Although fluororesin-based artificial blood vessels are small-diameter artificial blood vessels and have superior long-term patency than polyester-based artificial blood vessels, they also have major drawbacks. When fibrillating the blood-contacting surface during manufacturing, stretching is performed, and this stretching causes the molecules to be oriented in the stretching direction. This is something that is easy to do. Even in actual laboratory tests and practical tests, rupture along the length of the artificial blood vessel occurs, or a portion of the artificial blood vessel swells, just like an arterial stent, and this swollen part is extremely It becomes easier to avoid. This is a phenomenon equivalent to static stasis and arterial sound generation in the human body, and it is extremely important to overcome these drawbacks in practical use.

Conventionally, in artificial blood vessels made of fluororesin, in order to prevent this phenomenon, a separately stretched tape-like material of the same type is stretched substantially perpendicular to the length direction of the fluororesin artificial blood vessel.
Measures have been taken to prevent this by wrapping the artificial blood vessel around the artificial blood vessel and making the artificial blood vessel wall composed of two layers, one in the length direction and one oriented substantially at right angles to the length direction.

Alternatively, in order to prevent the molecules from arranging in the length direction and becoming easy to avoid along the longitudinal direction (the length direction of the artificial blood vessel), for example, a polypropylene thread can be wrapped around the outer periphery of the artificial blood vessel in a spiral shape. Some attempts have been made to achieve this goal by wrapping the fluororesin-based artificial blood vessel around the body, but there are still concerns that these methods can be used safely in arterial systems that are subject to pressure.

Polyurethane-based artificial blood vessels that are currently being developed have similar risks, and improvements in these are highly desired. Another problem is the kinking phenomenon.

When an artificial blood vessel is used as a substitute for a peripheral blood vessel, this kinking phenomenon easily occurs when the knee or elbow is bent, and there has been a strong desire for an artificial blood vessel that does not cause this kinking phenomenon even when bent to a considerable degree of curvature.

[Means for solving problems]

In order to solve the above-mentioned problems, the present inventor studied structural aspects and made various attempts, and as a result 1, he arrived at the present invention.

The gist of the present invention is to provide an artificial blood vessel made of synthetic resin, particularly fluororesin or polyurethane, in which, as shown in FIG. An annular protrusion 3 is provided along the outer periphery in a direction substantially perpendicular to the horizontal direction, and the average half width w (*n) of the annular protrusion 3 is between 0 and the average height h (w) of the protrusion. There is a relationship of IT≦W≦2T−・−・−・(1), and while this annular projection goes around the artificial blood vessel, it intertwines with the adjacent annular projections in at least three places. The present invention relates to an artificial blood vessel characterized in that the two are integrated to form a peripheral protrusion.

Here, the half width is the height of the annular protrusion 3 minus the height, that is, the width w (m) of the annular protrusion at -h (MM).
It is. It is preferable that the annular projection 3 satisfies W≦−T,
It is more preferable that ≦−T.

The annular protrusion 3 formed on the outer circumference 2 is integrally formed with the artificial blood vessel tube 1, and the number n of the annular protrusions is:
For example, the relationship between the inner diameter # (mm) of the artificial blood vessel and the average number of annular protrusions within the length of this artificial blood vessel is within the range of the following relational expression % (2) and the artificial blood vessel tube ] 0.1 d≦ between the thickness d(n) and the average half-width w(mm) of the annular protrusion
7≦10 d It is preferable to satisfy the condition (3) in order to exhibit kink resistance against bending and to exhibit strong bursting strength. In other words, if the number n of annular protrusions is less than the above condition (7) with respect to the inner diameter l, there will be no bending flexibility and a kinking phenomenon will occur, resulting in an unnatural appearance.If the number of protrusions is too large, the elasticity will be lacking and the shape will look as if it were There may be cases where it becomes like a thick-walled tube and cannot be bent. Therefore, it is preferable to satisfy the condition of the above formula (2) because it can be easily bent to a steep angle. It is desirable that the annular protrusion 3 in the present invention be made of the same material as the artificial blood vessel tube.

The formula (1) is more preferably 1≦W≦T−・−1−−・
...(1)' is within the range.

Equation (2) is more preferably 0.21! ≦7≦4I!・−1−−−−−−−−−
−・・−・(2)′, and formula (3) is more preferably 0.3d≦7≦5 d, −−−−−−−−−−−・
... (3) It is between '. In addition, when suturing an artificial blood vessel during surgery, it is easier to suture the thinner the artificial blood vessel wall, and long-term patency depends on the quality of the suture finish. Very important. 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, it is preferable to define the wall thickness d and the half-width of the annular protrusion as shown in equation 3), so that the bursting strength is sufficient and the sutureability is
It has excellent anastomotic properties and can be bent to 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 curvature without any kinking phenomenon.

Expressed in another way, the present invention regulates the protrusion height of the annular protrusion within a certain range with respect to the cross-sectional width of the annular protrusion of the artificial blood vessel,
Preferably, if the number of annular protrusions is defined within a certain range for the diameter of the artificial blood vessel, and preferably the cross-sectional width of the annular protrusions is regulated within a certain range for the wall thickness of the artificial blood vessel, the bursting strength is strong and kinking is achieved. They discovered that the artificial blood vessel could be bent into sharp curves without any phenomenon.

According to the present invention, in an artificial blood vessel having an inner diameter of A'(w), the radius of curvature r(
-) is 1.51 or less, furthermore 1.01 or less, furthermore 0.8f
It is possible to bend the following without kinking phenomenon. 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, so when the artificial blood vessel is bent, the center of curvature side (inside) of the bending of the artificial blood vessel can shrink. This is because the outer side (direction far from the center of bending, that is, the center of curvature) is given the property of being stretchable.

In order to be able to bend with a small radius of curvature without the kinking phenomenon, it is desirable that this artificial blood vessel has elasticity, and the natural length in the unloaded state shown in FIG. 3A. As shown in Figure 3B, the length of the artificial blood vessel when compressed in the longitudinal direction is 0.1Lo≦Lp≦0.7L.

Preferably 0.3LO≦L, ≦0.6L.

More preferably 0.3L, ≦I≦0.5LO An artificial blood vessel that can be compressed within the range of

It is preferable that the annular protrusion 3 of the artificial blood vessel of the present invention be irregular rather than regular. The reason for this is that irregular intertwining allows stress to be transmitted in all directions, resulting in higher burst resistance.

In other words, since a rupture is caused by a localized force and a tear occurs in a mechanically weak area, it is easier to compensate for local defects if the annular protrusions are arranged randomly.

The advantage of the artificial blood vessel of the present invention is that the average half-width w (m
), the average distance between adjacent annular protrusions D (m)
is preferably set between 0.37≦D≦157.

Such a product can be made by appropriately changing the molding conditions in the case of a fluororesin, as will be described later in the examples, and in the case of polyurethane, the intervals between the annular protrusions may be appropriately spaced during processing.

The fluororesin used in the present invention is polytetrafluoroethylene, and other substances such as acrylic resin or polyurethane may be added for the purpose of modification. or polytetrafluoroethylene copolymers such as tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-propylene copolymer, trifluoroethylene chloride, fluoroethylene Vinylidene chloride may also be used.

As the polyurethane, either polyester-based, polyether-based polyurethane urea or polyurethane can be used. As polyurethanes, those containing polytetramethylene oxide as a soft segment component are particularly useful from the viewpoint of mechanical properties.

[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 such as high burst strength and bendability with a small radius of curvature. This makes it possible to provide an artificial blood vessel with excellent long-term patency.

〔Example〕

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

(Examples 1 to 6) Polytetramethylene glycol having a molecular weight of 1600 and having hydroxyl groups at both ends was reacted with 4,4' diphenylmethylene diisocyanate in dimethylacetamide to produce a prepolymer having isocyanates at both ends, and this was prepared by a conventional method. Polyurethane urea was synthesized by chain extension with ethylenediamine. Next, methanol was added to cause precipitation, and the precipitate was dissolved again in dimethylacetamide to remove insoluble gel-like substances, and then methanol was added to cause precipitation.

This polyurethane was again dissolved in dimethylacetamide to make a 16% solution, which was extruded through an annular slit and solidified into water either directly or after passing through an air layer. 8m, 10 dragons, 13
A polyurethane tube 6 with a diameter of 6 mm was prepared (see Fig. 4). Insert the stainless steel rods 7 into the inner cavities of these tubes so that they are in close contact with each other, and rotate the stainless steel rods 7 with the length direction as the axis of rotation.1 As shown in Fig. 4, the concentrated polyurethane solution 8 is applied at a constant speed. It is extruded from the nozzle 9 onto the outer wall of the polyurethane tube 6, and the stainless steel rod is moved in a certain direction and guided into the drying oven 1. The applied polyurethane solution was stretched in a direction perpendicular to the axis of rotation by centrifugal force, entered a drying oven, the solvent was evaporated, and a spiral annular protrusion 11 was formed on the tube that came out of the oven.

In this case, by moving the polyurethane concentrated solution discharging nozzle 9 in the length direction of the tube 6 and extruding it onto the tube, adjacent annular protrusions can be intertwined with each other. The dimensions of the artificial blood vessels thus produced were as shown in Table 1.

(The following is the margin, continued on the next page.) 1--” knee table (Note) The meaning of each symbol in the table is as follows.

T: Average height of the annular protrusion) W: Average half width of the annular protrusion (1 m) n: Inner diameter j
2 (mm), the length of the artificial blood vessel l +++++ Average number of annular processes within the interval d: Wall thickness of the artificial blood vessel tube (fin) l: Inner diameter of the artificial blood vessel (fin) D: Average spacing between the annular processes (11) r: Minimum radius of curvature that can be bent without kinking (-
m) (Example 7) A polyurethane tube with an inner diameter of 6 mm was made using polyurethane synthesized in the same manner as in Example 1, except that butanediol was used as a lengthening agent, and a stainless steel tube was made into this tube in the same manner as in Example 1. A rod is inserted, and while the stainless steel rod is rotated along its longitudinal centerline, a concentrated polyurethane solution is irregularly and intermittently moved in the length direction of the tube and discharged to form a band on the outer wall of the polyurethane tube. Adjacent polyurethane strips were made to intertwine with each other.

The concentrated solution of polyurethane on the polyurethane tube is stretched by centrifugal force in the direction of the centrifugal force, ie, perpendicular to the length of the tube. In this state, the stainless steel mandrel was introduced into a drying oven to remove the solvent, resulting in an artificial blood vessel having annular projections that were intertwined with each other and were approximately perpendicular to the length direction of the tube.

The average height of the annular protrusion of this artificial blood vessel is 1.5 cranes, and the length is c.
The number of protrusions in fl is 7, the average half width is 0.5 m, the average distance between the annular protrusions (D) is 0.8 m, and the wall thickness (d) is 0.8
This is Tomiyoshi.

In this case, the glue/LO was 0.40.

(Example 8-12) (See Figure 5) 1 kg of commercially available tetrafluoroethylene resin (Teflon manufactured by Mitsui Fluorochemical Co., Ltd.) and white oil as an extrusion aid (liquid lubricant) (Sumoil P-55° sealing cap) (manufactured by Sekiyusha) 2
60 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.

In this state, the stainless steel rod 13 is inserted into the inner cavity of the tube 12 so as to be in close contact therewith, and while rotating the stainless steel rod 13, a cut 15 is made with a sharp knife 14 leaving a part of the inner wall of the tube.

The cuts 15 are not completely circumferential, but are made here and there. At this time, three unbroken areas 16 are created per circumference. The lateral spacing between cuts may be precise or intentionally inaccurate.

This tube is stretched 1.2 to 10 times at a temperature of 327°C or lower, preferably about 200°C. In this example, 20c
m tube heated to 200℃ and rapidly heated to 100℃.
It was stretched into pieces. By this treatment, the cut portions are strongly stretched, and since no force is applied between the cuts, they are not stretched, resulting in the structure of the present invention as shown in FIG. 3A.

Fix both ends of the stretched tube to prevent it from shrinking, connect a pipe to introduce cooling air to one end of the tube, close the other end, raise the temperature, and when it reaches 320℃, it will reach O'', 4k.
An air pressure of g/c+d was rapidly introduced, the temperature was raised while maintaining this air pressure, and when it reached 400° C., it was then rapidly cooled to return to room temperature. In this way, we created an artificial blood vessel with the following inner diameter and configuration. This artificial blood vessel has an extremely small curvature and can be bent without kinking.

The results are summarized in Table 2 below.

(The following margins are continued on the next page.) Symbols in the 11th L-Part table have the same meanings as shown in the footnotes of Table 1.

[Effects of the Invention] According to the present invention, artificial blood vessels made of synthetic resins such as fluororesin and polyurethane have high bursting strength and can be used as arterial blood vessels.Moreover, they can be bent without kinking with a small radius of curvature, and can be used as peripheral blood vessels. It has now become possible to provide an artificial blood vessel that can be used as a substitute and has excellent long-term patency.

[Brief explanation of the drawing]

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 shown in Figure 1A, Figure 2 is a partial front view of the artificial blood vessel shown in Figure 1 in a bent state, and Figure 3A is a view of the artificial blood vessel shown in Figure 1 in an unloaded state. Schematic front view,
FIG. 3B is a schematic front view of the artificial blood vessel shown in FIG. 3A in a compressed state, and FIGS. 4 and 5 are diagrams for explaining the method of manufacturing the artificial blood vessel of the present invention. In addition, in the symbols used in the drawings, 1...--1--------... Artificial blood vessel tube 2---11-------------- Outer peripheral part 3 .1
1・・・・・−・−・−It is an annular projection.

Claims (1)

[Claims] An artificial blood vessel made of synthetic resin, in which an annular protrusion is provided along the outer periphery of the artificial blood vessel tube, and the average half-width @w@(mm) of the annular protrusion and the annular protrusion are Average height @h
There is a relationship between 0.1@h@≦@w@≦2@h@ and @ (mm), and this annular process has a relationship between it and the adjacent annular process while going around the artificial blood vessel. An artificial blood vessel characterized by being intertwined and integrated at at least three locations to form a peripheral protrusion.