JPS61272047A - 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 with an annular protrusion along the outer periphery of the artificial blood vessel tube to restrict compressibility along the length of the artificial blood vessel to a specific range, thereby achieving kinking. The purpose of this invention is to obtain an artificial blood vessel that can be bent with a small radius of curvature without the phenomenon of breaking when bent, has high bursting strength, and has excellent long-term patency.

(Prior Art) Currently, artificial blood vessels made of knitted fabrics of polyester fibers and fluororesin-based artificial blood vessels are mainly used.Polyester-based artificial blood vessels have a chemical structure of polyethylene terephthalate. Consisting of fibers with
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 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 vessel in a pressure-sensitive animal or pig system.

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 at a curved 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 longitudinal direction, and the length L of the artificial blood vessel in an unloaded state is
o and the length LP of the artificial blood vessel when compressed in the length direction of the artificial blood vessel, which has a relationship of 0, I Lo 5Lp≦0.7LO. .

Preferably, the artificial blood vessel of the present invention is characterized in that the radius of curvature r (ms) that can be bent without kinking is 1.51 (/ is the inner diameter fl of the artificial blood vessel) or less.

The artificial blood vessel of the present invention is provided with an annular protrusion along the outer periphery in a direction substantially perpendicular to the length direction of the artificial blood vessel, and the average half-width w (mu) of the annular protrusion is equal to the average height h (mm) of the protrusion. There is a relationship of 1≦W≦2h・・−・−・・−・(1) between (
(see Figure 1), and it is desirable that this annular protrusion intertwine and integrate with adjacent annular protrusions in at least three places while going around the periphery of the artificial blood vessel to form a peripheral protrusion. .

Here, the half-width is the width w (m) of the annular projection 3 at the negative height of the annular projection 3, that is, -h (m). It is preferable that the annular projection 3 satisfies Ma≦−T, and ≦
--h is more preferable.

The annular projections 3 formed on the outer circumferential portion 2 are integrally formed with the artificial blood vessel tube 1, and the number n of the annular projections is as follows:
Inner diameter of artificial blood vessel! ! (ms) and the length l of this artificial blood vessel
The average number of annular protrusions in ll is within the range of the following relational expression % (2), and the thickness d (dragon) of the artificial blood vessel tube l and the average half-width of the annular protrusions Ma (0.1d≦≦ between weight
It is preferable to satisfy the condition LOd--------(3) in order to exhibit kink resistance against bending and to exhibit strong bursting strength. That is, the number n of annular protrusions
If the inner diameter l is less than the above conditions, there will be no bending flexibility and a kinking phenomenon will occur, resulting in an unnatural appearance.If there are too many protrusions, the tube will lack elasticity, making it look like a thick tube. There may be cases where the object 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. The annular protrusion 3 in the present invention is preferably made of the same material as the artificial blood vessel tube.

The formula (1) is more preferably in the range -≦≦h-.-(1)'.

The formula (2) is more preferably in the range of Q, 21sn≦41−・−・・−−(2)′, and the formula (3) is more preferably in the range of 0.3d≦≦5d−−−−1 −−・・−・・−(3)
' 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), which provides sufficient bursting strength and excellent suturing and anastomosis properties.
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.

According to the present invention, in an artificial blood vessel having an inner diameter of 1 f (mm), the radius of curvature r of the center 494 (see FIG. 2) of the artificial blood vessel is
(m) is 1.51 or less, and 1. O2 or less, further 0.
It is possible to bend up to 81 mm or less without any 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.

This artificial blood vessel has elasticity because it can be bent with a small radius of curvature without the kinking phenomenon, and the length of the artificial blood vessel as shown in Figure 3B is different from the natural length L0 in the unloaded state in Figure 3A. The relationship between the length when compressed in the longitudinal direction and the length p is 0.1L, ≦LP≦0.7Lo, and preferably 0.3L, ≦Lp≦0.6L.

More preferably 0.3LO≦Lp≦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 irregular intertwining allows stress to be transmitted in all directions, resulting in higher burst resistance. In other words, when a rupture occurs, a force is applied locally and a tear occurs in a mechanically weak area, so it is easier to compensate for local defects if the annular protrusions are randomly configured.

In the artificial blood vessel of the present invention, the average half-width (,)
In contrast, it is preferable to set the average distance D (dragon) between adjacent annular protrusions to a range of 0.3w≦D≦15w.

1. As will be described later in the examples, fluororesin-based products can be made by appropriately changing the molding conditions, and polyurethane products can be made by appropriately spacing the annular protrusions 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 ethylene chloride, and vinylidene fluoride may 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 diisocyanenite in dimethylacetamide to prepare a prepolymer having isocyanates at both ends. Polyurethane urea was synthesized by chain extension with ethylenediamine by the method. 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. ■, 81 Otori, 10n
, 131m of polyurethane tube 6 was made (4th
(see figure). The stainless steel rods 7 are inserted into the inner cavities of these tubes so that they are in close contact with each other, and the stainless steel rods 7 are rotated with the length direction as the axis of rotation.As shown in FIG. 4, the concentrated polyurethane solution 8 is poured 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 is stretched in a direction perpendicular to the rotation axis by a centrifugal crab, and then enters a drying oven where the solvent evaporates.
A spiral annular protrusion 11 was formed on the tube that came out of the furnace.

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.

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

T: Average height of the annular process (fin) M: Average half-width of the annular process (cut) n: Inner diameter! (wm), the average number of annular protrusions within one interval of the length of the artificial blood vessel d: The wall thickness of the artificial blood vessel tube (Tsuru) l2 The inner diameter of the artificial blood vessel (1 m) D: The average distance between the annular protrusions ( fI) r: Minimum radius of curvature (dragon) that can be bent without kinking (Example 7) A polyurethane with an inner diameter of 6 mm was prepared using polyurethane synthesized in the same manner as in Example 1 except that butanediol was used as a chain extender. A tube is made, a stainless steel rod is inserted into it in the same manner as in Example 1, and while the stainless steel rod is rotated along the center line in the longitudinal direction, a concentrated polyurethane solution is applied irregularly and intermittently along the length of the tube at appropriate times. It was discharged while moving and applied to the outer wall of the polyurethane tube in a band shape, so that adjacent polyurethane bands were intertwined 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 6
The number of protrusions in 11 is 7, the average half width is 0, 5 + n,
Average distance between annular protrusions (D) is 0.81■, wall thickness (d)
is 0.8 dragon.

Lp/Lo in this case 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 (Sumoil P-55° as an extrusion aid (liquid lubricant)) (manufactured by Kenyusha)
260 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 heated 1.2 times to 10 times at a temperature below 327°C.
Stretch it twice as much, but it is appropriate to stretch it at about 200°C. In this example, 20
10 cm tube heated to 200°C.
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.
An air pressure of /c+a 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.

The symbols in Table 2 have the same meanings as given in the footnotes to Table 1.

〔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---111-------Artificial blood vessel tube 2----------f1 circumferential portion 3.11・
-------It is an annular projection.

Claims (1)

[Claims] 1. 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 length L_o of the artificial blood vessel in an unloaded state and the An artificial blood vessel characterized by having a relationship of 0.1L_o≦L_p≦0.7L_o with the length L_p of the artificial blood vessel when compressed in the length direction of the artificial blood vessel. 2. The artificial blood vessel according to claim 1, wherein the radius of curvature r (mm) that can be bent without kinking is 1.5 l (l is the inner diameter mm of the artificial blood vessel) or less.