JPS61293451A - 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 the average half width of the annular projection, the average height of this annular projection, and the wall thickness of the artificial blood vessel tube are provided. By specifying the number of annular protrusions within a certain range, it is possible to obtain an artificial blood vessel that can be bent without kinking (a phenomenon of breaking when bent), has high bursting strength, and has excellent long-term patency. It is something.

[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 used by binding polytetrafluoroethylene as a component and hot stretching it to form fibrils (fine fibers) on the blood contact surface.

[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 part of the artificial blood vessel swells just like an arterial sound, and this swollen part is extremely It becomes easier to avoid. This phenomenon corresponds to venous retention 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 making it easy to avoid them along the longitudinal direction (the length direction of the artificial blood vessel), for example, polypropylene threads may 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 vessels in arterial systems that are subject to high 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 inventors studied structural aspects and made various attempts, and as a result, they 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 projection 3 is provided along the outer periphery in a direction substantially perpendicular to the lateral direction, the annular projection 3 is made of the same material as the artificial blood vessel tube, and has an inner diameter 1 (a) of the artificial blood vessel.
m), the wall thickness d (mu) of the artificial blood vessel tube, the average height of the annular process (dragon), the average half-width of the annular process m (,,), and the annular shape within the interval j2 (mu). Between the average number of protrusions, 1≦Ma≦2T −・−・・−・−−−−−1111・・
−(1)0.21≦T≦51−・・−−１−・−−−
−(2) 0.1 d≦≦10d−・−1−−・・・～
(3) The width w (mm) of the annular protrusion is the width of the annular protrusion. The annular protrusion 3 is formed on the outer peripheral part 2 and the annular protrusion 3 is attached to the artificial blood vessel tube 1.
In addition to the condition (1) 2 above, the number n of these annular protrusions is determined by the inner diameter J (mm) of the artificial blood vessel and the average number of annular protrusions within the length l1 of this artificial blood vessel. 7 and satisfy the conditions of formula (2) above, and the thickness d (mm) of the artificial blood vessel tube 1 and the average half-width (mm) of the annular protrusion
The present inventors have discovered that when the condition of the above formula (3) is satisfied between the above conditions, it exhibits anti-ginking properties against bending and exhibits strong bursting strength. In other words, if the number n of annular protrusions is less than the above condition relative 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, making it look like flesh. It becomes like a thick tube and cannot be bent. Therefore, if the condition of the above formula (2) is satisfied, it can be easily bent to a steep angle. The annular projection 3 in the present invention is made of the same material as the artificial blood vessel tube.

The formula (1) is more preferably 1≦ma≦T...---1-
It is in the range of −・−(1)′.

The formula (2) is more preferably in the range of 0.2N≦7≦41--(2)', and the formula (3) is more preferably in the range of 0.3 d≦≦5 d −−−−−−−−・−・・−・・
(3) Between ゛. In addition, when artificial blood vessels are used surgically,
Thinner walls of the artificial blood vessel are easier to suture, and long-term patency is determined by the quality of the suture finish, so it is very important that the anastomosis and suturing are easy. 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, by defining the wall thickness d and the half-width of the annular protrusion as shown in equation (3), the bursting strength is sufficient and the suturing and anastomotic properties are excellent.
Moreover, the radius of curvature can be bent to a small value without any kinking phenomenon. 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,
By specifying the number of annular protrusions within a certain range for the diameter of the artificial blood vessel, and regulating the cross-sectional width of the annular protrusions within a certain range for the wall thickness of the artificial blood vessel, the bursting strength is strong (it is possible to make sharp curves without kinking). They discovered that it can be used as an artificial blood vessel that can be bent.

According to the present invention, in an artificial blood vessel with an inner diameter of 1 (mm), the radius of curvature r (m
u) is 1.51 or less, and further 1. O1 or less, further 0.8β
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 the artificial blood vessel with a small radius of curvature without the kinking phenomenon, it is desirable that the artificial blood vessel has elasticity. The length when compressed in the longitudinal direction of the blood vessel is 0.1 L, ≦Lp≦0.7 L.

Preferably 0.3 L o ≦LP ≦0.6LQ, more preferably 0.3LO≦L2≦0.5L.

An artificial blood vessel that can be compressed within the range of

It is preferable that the annular protrusions 3 of the artificial blood vessel of the present invention be irregular rather than regular, and that the annular protrusions 3 intertwine and integrate with adjacent annular protrusions at at least three places while going around the artificial blood vessel. It is preferable that the The reason for this is that if the particles are irregularly intertwined, the reaction force will 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.

In the artificial blood vessel of the present invention, the average half width (dragon)
In contrast, it is preferable to set the average distance D (crane) between adjacent annular projections to a range of 0.3≦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 n
It may be a fluoroalkoxy vinyl ether copolymer, a tetrafluoroethylene-ethylene copolymer, a tetrafluoroethylene-propylene copolymer, trifluoroethylene ethylene chloride, or vinylidene fluoride.

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 hydroxyl groups at both ends of molecule 11600 and 4,4' diphenylmethylene diisocyanate were reacted in dimethylacetamide to produce a prepolymer of isocyanate 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 dissolved in dimethylacetamide again 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 to form three layers with inner diameters (1) of 3W, 4FI, and 5 layers, respectively. layer, 1llll,
A polyurethane tube 6 with a length of 10 cm and 13 m1 was made (see Fig. 4). The stainless steel rods 7 are inserted into the inner cavities of these tubes so as to be in close contact with each other, and the stainless steel rods 7 are rotated with the length direction as the rotation axis, as shown in FIG.
A concentrated polyurethane solution 8 is extruded at a constant speed from a nozzle 9 onto the outer wall of the polyurethane tube 6, and this stainless steel rod is moved in a constant direction and guided into the drying oven 1.The applied polyurethane solution is rotated by centrifugal force. The tube extends perpendicularly to the axis, enters the drying oven, the solvent is evaporated, and the tube that comes out of the oven has a spiral annular protrusion 1.
1 was formed.

In this case, by moving the concentrated polyurethane solution discharging nozzle 9 in the longitudinal 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.

(Note) The meaning of each symbol in the table is as follows.

T: Average height of the annular projection (1) M: Average half-width of the annular projection (,■) D: Inner diameter A'
When (u+), the average number of annular protrusions within the length IB interval of the artificial blood vessel d: Thickness of the artificial blood vessel tube (dragon)! ! 2. Inner diameter of artificial blood vessel (Tsuru) D: Average distance between annular protrusions (Dragon) r: Minimum radius of curvature that can be bent without kinking (wm
) (Example 7) A polyurethane duplex 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 chain extender, and the polyurethane duplex was treated in the same manner as in Example 1. A stainless steel rod is inserted, and while the stainless steel rod is rotated along its longitudinal center line, the concentrated polyurethane solution is irregularly and intermittently moved in the length direction of the tube and discharged to coat the outer wall of the polyurethane duplex. The polyurethane strips were applied in strips so that adjacent polyurethane strips were intertwined with each other.

The concentrated polyurethane solution portion of the polyurethane duplex 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 mm, and the length is 6 mm.
The number of protrusions in the dragon is 7, the average half-width is 0, the average distance (D) between the 5 dragons, the annular protrusions is 0.81, and the wall thickness (d) is 0.
It is 81.

LP/L o in this case was 0.40.

(Example El-12) (See Figure 5) 1 kg of commercially available tetrafluoroethylene resin (Teflon manufactured by Mitsui Fluorochemical Co., Ltd.) and white oil (Sumoil P-55° capper) as an extrusion aid (liquid lubricant) (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 is then heated to a temperature below its boiling point.
ζ was sufficiently removed.

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 cut 15 is not completely circumferential, but cuts 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 times to 10 times at a temperature of 327°C or lower, but approximately 200°C is suitable. In this example, 20c
m tube heated to 200'C and rapidly lo
It was stretched to 0 cm. 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 weigh 0.4kg.
/ctacv air pressure was rapidly introduced, the temperature was raised while maintaining this air pressure, and when it reached 400° C., it was then rapidly cooled down to room temperature. In this way, artificial blood vessels with the following inner diameters and shapes were created. This artificial blood vessel can be bent with extremely small curvature without kinking.

The results are summarized in Table 2 below.

〔Effect of the invention〕

According to the present invention, an artificial blood vessel made of synthetic resin such as fluororesin or polyurethane has a high bursting strength and can be used as an arterial blood vessel, and has a small radius of curvature and can be bent without kinking, so it can be used as a substitute for a peripheral blood vessel. It has become possible to provide artificial blood vessels with excellent long-term patency.

[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 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 codes used in the drawings, 1. .1
1・−・−・・−1111−・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 annular protrusion is made of the same material as the artificial blood vessel tube. The inner diameter l (mm) of the artificial blood vessel, the wall thickness d (mm) of the artificial blood vessel tube, and the average height of the annular protrusion @h@(
mm), the average half-width @w@(mm) of the annular protrusion, and the average number n of the annular protrusions within lmm interval @h@/10≦@w@≦2@h@…… ...(1)0.
An artificial blood vessel characterized by having the following relationship: 21≦@n@≦5l (2) 0.1d≦@w@≦10d (3).