JP2839126B2 - Branched artificial blood vessel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved bifurcated vascular prosthesis capable of completely preventing blood leakage occurring at a bifurcation of a bifurcated or triprosthetic vascular prosthesis.

[0002]

2. Description of the Related Art The history of artificial blood vessels reaches more than 30 years as soon as they have been put to practical use. In particular, polyester artificial blood vessels and artificial blood vessels made of stretched fluororesin are being used in the world as excellent ones. In these artificial blood vessels, the tube wall is rich in porosity, and endothelial cells grow on the inner surface of the artificial blood vessel after transplantation and become a living body, thereby substituting the original blood vessel. It has been thought that the void plays an important role in the bioartificialization of the artificial blood vessel.

[0003] Normally, a straight tube has been used as an artificial blood vessel at first. However, in order to cope with complicated hemodynamics, it is necessary to substitute a part of a living blood vessel which is stretched all over the body. Means that when a vascular lesion exists in only one place,
Straight vascular prostheses are very convenient. However, in general, a person having a lesion in a blood vessel often has a plurality of lesions.

In such a case, the diseased part is replaced, or the diseased part is left as it is to create a bypass to secure a normal blood flow. In this case, a branched artificial blood vessel is used. It is very convenient because a plurality of lesions can be treated with one artificial blood vessel. In the case of a dangerous lesion such as an aneurysm in a living vascular lesion, a bypass may be created by completely blocking the portion with an artificial blood vessel. Further, when an originally branched portion of a living blood vessel forms an aneurysm, a branched artificial blood vessel is naturally required. Further, when there are a plurality of occlusions and stenosis of a living blood vessel, it is extremely convenient if there is a branched artificial blood vessel.

[0005] From the point of view of the doctor, when making a bypass using two linear blood vessels, four places of anastomosis are necessary.
If a Y-shaped artificial blood vessel is used, only three anastomoses are needed,
The effect is great in reducing the labor required. Accordingly, its usefulness is well recognized because the burden on the patient can be reduced by safety and shortening of the operation time. Therefore, it is natural that a branched artificial blood vessel is accepted in the market, and there is a great demand from the market for a Y-shaped, T-shaped or two to three bifurcated, three-branched branched artificial blood vessel.

[0006]

As described above, a branched artificial blood vessel is extremely useful for both a physician who performs a procedure and a patient who undergoes the procedure. However, there is an unavoidable problem heretofore. This will be described using a Y-shaped artificial blood vessel. FIG. 1 shows a typical Y-shaped artificial blood vessel. Here, the positional relationship is shown in an inverted Y-shape. That is, the relatively thick artificial blood vessel indicated by A is divided into relatively thin bifurcations indicated by B and C. The practitioner and his / her assistant transplant this sterilized branched vascular graft into the patient.
During handling, in the directions indicated by the arrows on the branches B and C,
If a slight force is applied by mistake, the force concentrates on the contact point (point P) or the crotch of the branch pipes B and C, and the texture of this section is pulled in the directions of B and C to loosen the fiber spacing (mesh). Opening).

[0007] Even if the opening of this portion has little difference in visual inspection by applying a slight force in handling, there is a case where the fiber assembly loosens to loosen the texture. Of course, although this is well understood by the practitioner and pays attention to the handling, the force between the branches B and C does not always happen to occur during the handling. In this case, even if a force is applied between the main pipe A and the branch pipe (B or C), a large force is not applied to the crotch point Q between the main pipe and the branch pipe, but the force is applied between the branch pipes B and C in the direction of the arrow. In this case, a force is applied so as to tear the crotch, and the weave of the weave at the contact point (crotch) of the branch pipe is most feared. Although these possibilities may occur during the handling of the practitioner, even if the quality control tests are sufficiently performed during the manufacturing process, for example, even when the final process is packaged after the tests, the caretaker may be inadvertently injured. There is no danger that a force will be applied in the middle and the texture of the crotch will be loosened. Then, it is extremely difficult to grasp the occurrence of such relaxation at first glance.

[0008] On the other hand, when a practitioner implants an anastomotic implant into a living blood vessel with such a branched artificial blood vessel in which the crotch portion is relaxed, the blood introduction after the operation starts, the open portion of the texture of the relaxed portion is opened. Blood may leak, and in severe cases it may rush. This has very serious consequences. That is, the patient may be faced with a life-threatening serious condition that may result in death.

As described above, the relaxation of the crotch portion of the branched artificial blood vessel causes a serious problem for the patient, and the frequency of the problem is completely eliminated even if careful quality control and production control are performed. It is actually difficult to do so. Needless to say, it is required to eliminate these disadvantages in terms of safety and effective life.

[0010]

SUMMARY OF THE INVENTION The present inventors have found that the frequency of openings is extremely low even with careful quality control, quality inspection, and precise manufacturing processes. As a result of extensive studies, a method of completely eliminating the occurrence of a defect such as opening caused by loosening of the weave between the branches of the artificial blood vessel and the junction of the main pipe and the branch pipe (the crotch) which falls into a serious situation was examined. Apply a coating of an elastic polymer material to the part of the blood vessel where the opening is most likely to occur with a slight stress, and form a thin film of a polymer elastic material there, even if the stitches of the branched crotch loosen loosely Also found that it was possible to completely seal the blood leak and reached the present invention.

According to the present invention, in an artificial blood vessel having a branch, a polymer elastic material is coated on at least the range of the diameter of the branch pipe centered on the crotch point between the branch pipes branched from the main pipe or the crotch point at the base of the branch pipe and the main pipe. The present invention relates to a branched artificial blood vessel. And, the elastic polymer is preferably polyurethane or polysiloxane.

In the present invention, the crotch portion is defined as P in FIG.
It is near the point (interbranch crotch point) and near point Q or Q '(main pipe-branch crotch point). Also, in the case of a branched artificial blood vessel as shown in FIGS. 2A, 2B, and 2C, the points P and Q are the crotch points, and the periphery thereof corresponds to the crotch. In this case, what is most important is a portion where the angle of the crotch is a right angle or smaller, and a portion where the texture is most likely to be opened by a slight force applied by the operator. That is, in FIG. 2, the opening is most likely to occur when opening in the direction of the arrow around the point P.

The coating material of the polymer elastic body of the present invention has an elasticity which is an essence of the polymer elastic film even if the above-mentioned crotch fiber assembly is opened due to the inherent elasticity of the polymer. As a result, there is no crack, so that the potential risk of the branched artificial blood vessel can be removed by 100%.

In practicing the present invention, the area coated with the polymer elastic body of the present invention is, in the case of a Y-shaped branched artificial blood vessel, an acute angle forming point where a branch pipe divided from the main pipe intersects, that is, a crotch point (crotch part). Center point), and within the range of the diameter of the branch pipe (FIG. 3: l), more preferably l / 2
It is good to coat within the range. In the case of a T-shaped branched artificial blood vessel, it is preferable to coat the circumference of the base of the branch pipe (FIG. 4: the circumference of the branch pipe including the crotch points P and P ′). Preferably, the area is coated over a range of width l along the circumference of the branch including the crotch point. More preferably, the coating is performed within the range of l / 2. FIG. 5 shows a coating range by a dotted line in a cross-sectional view taken along the line DD of FIG. FIG. 6 exemplifies a coating range when coating is performed at a width of l / 2 of the diameter l of the branch pipe along the circumference of the branch pipe including the crotch point P. The need to make the width of the coating area larger than the diameter l of the branch is not too great in light of the spirit of the invention.

The material of the elastic polymer used in the practice of the present invention is preferably a material having excellent biocompatibility, such as polyether polyurethane, polyether polyurethane urea, polyester polyurethane, polyester polyurethane urea, and the like. Examples thereof include polysiloxane represented by silicone, and natural rubber.
Among them, polyurethane and polysiloxane are preferable in terms of biocompatibility and elasticity.

The polymer elastic material to be coated may be used after being dissolved in a solvent. However, a monomer or oligomer which is converted into the above-mentioned elastic polymer by a condensation reaction, ie, a precursor which can be converted into a polymer elastic material, is used. After coating, polycondensation or addition polymerization may be carried out to convert to a desired polymer elastic body.

Examples of the solvent for dissolving the elastic polymer or its precursor include dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran and dioxane. Also,
In the case of a precursor, acetone, methyl acetate, and dioxane may be used in addition to the above solvents.

The coating of the present invention can be coated on the outside or inside of the artificial blood vessel or from both sides, but it is most preferable to coat from the outside. This is because coating on the inside may delay the engraftment of endothelial cells from the blood in that portion.

The types of artificial blood vessels applied in the practice of the present invention include a polyester woven artificial blood vessel, a knit artificial blood vessel, an artificial blood vessel made of a stretched fluororesin, and a polyurethane artificial blood vessel. In light of the above, the type is not particularly limited.

[0020]

According to the present invention, a portion corresponding to the bifurcation, such as a bifurcation, a trifurcation or a quadruple, which corresponds to the base of the branch and the crotch, is coated with an elastic polymer, and the elastic polymer is applied to that part. By forming the thin film, the blood leakage trouble due to the loosening between the fibers in the portion where the opening is most likely to occur, which has been a problem in the past, has been completely prevented, and its safety has been secured.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

【Example】

Example 1 A Y-shaped branched artificial blood vessel shown in FIG. 1, having a main pipe (thick portion) having a diameter (L) of 28 mm and a branch pipe having a diameter (l) of 14 m
A polyether polyurethane solution (concentration: 12%, solvent: tetrahydrofuran) was coated from the outside around a center point (P) of the crotch portion of the polyester artificial blood vessel having a radius of 4 mm and dried for 2 hours. As a result, a thin coat of polyether polyurethane could be applied to the crotch. The polyether polyurethane used is a prepolymer made from polytetramethylene glycol and diphenylmethylene diisocyanate and subjected to chain extension with butanediol. The treated artificial blood vessel of FIG. 1 was pulled so as to open the crotch by applying a force so as to tear the two branches into the crotch. Bovine blood was injected into this and left for 1 hour in a state of being pressurized to 260 mmHg. As a result, there was no blood leakage or outbreak from the crotch.

Comparative Example 1 On the other hand, the operation was carried out under exactly the same conditions as in Example 1 except that the polyether urethane coating was not carried out. As a result, blood flowed linearly from the crotch due to the opening due to the cleft.

Example 2 A polyether urethane urea solution (concentration: 13%, solvent: dimethylformamide) was coated on the branched portion of a T-shaped branched woven artificial blood vessel shown in FIG. Drying was performed at 8 ° C. for 8 hours to form a polyether urethane urea thin film on a desired portion. The thin film was in a stable state, infiltrating into the fiber aggregate of the polyester artificial blood vessel, and hard to peel off.
The main tube (thick portion) of the artificial blood vessel used was 12 mm, and the side tube (branch) was 8 mm. The coating was applied over a width of 4 mm around the circumference of the side tube including the crotch points P and P 'shown in FIG. The polyether polyurethane used was obtained by extending a prepolymer prepared from polytetramethylene glycol and diphenylmethylene diisocyanate with ethylenediamine. The side tube (branch tube) of the T-shaped vascular prosthesis of FIG. 4 subjected to the above-described processing was alternately pulled ten times in the extension direction of the main tube so that the crotch part was opened.
Bovine blood was injected into this and left at 280 and 500 mmHg under pressure for 1 hour. As a result, neither blood leakage nor bleeding near the crotch point P was observed.

Comparative Example 2 The same operation as in Example 2 was performed except that the coating was not performed with the polyether polyurethane. As a result, when the pressure was 280 mmHg, a considerable blood leak was observed from around the point P of the crotch, and the pressure increased to 500 mmHg. When pressed, the blood burst out linearly.

Example 3 A solution of methyltriacetoxysilane and dimethyldiacetoxysilane (7: 3) near point P of a branched portion of a woven artificial blood vessel made of polyester branched in the forms (A) and (B) shown in FIG. (Concentration: 22%, solvent: tetrahydrofuran) was coated on the outer wall of the artificial blood vessel, air-dried as it was, and further left in an atmosphere of 65% relative humidity for one week. During this time, condensation proceeded while reacting with moisture in the atmosphere to release acetic acid, and coating with a condensate of polysiloxane was completed around the crotch point P. The main tube (thick part) of the artificial blood vessel used was 20 mm, and the side tube (branch) was 12 mm
Met. The coating was performed within a circle having a diameter of 8 mm centered on the crotch point P shown in FIG. The side tube (branch tube) of the T-shaped vascular prosthesis of FIG. 6 which has been subjected to the above processing was alternately pulled ten times in the extension direction of the main tube so that the crotch part was opened. Bovine blood was injected into this, and left at 260 mmHg for 1 hour. As a result, neither blood leakage nor bleeding near the crotch point P was observed.

Comparative Example 3 Example 3 except that the same coating as in Example 3 was not performed.
As a result, a remarkable blood leak was observed around the crotch point P.

Example 4 In a polyester artificial blood vessel branched into the shapes (A) and (B) shown in FIG. 6, a side tube (branch) including the points P in (A), the points P and Q in (B). Along the circumference of (a), the width is approximately equal to the diameter of the side pipe (within the hatched area in FIG. 5).
A mixture of dimethylpolysiloxane having a molecular weight of 2000 and having terminal hydroxyl groups and methyltriacetoxysilane (8: 2)
A solution (concentration: 20%, mixed solvent of tetrahydrofuran-dioxane (2: 1)) was coated on the outer wall of the artificial blood vessel, and left in an atmosphere of 60% relative humidity for 2 weeks.
During this time, methyl diacetoxysilane reacted with moisture in the atmosphere to release acetic acid, and condensation proceeded, and condensed with hydroxyl groups at both ends of polydimethylsiloxane to form a high molecular weight polydimethylsiloxane, completing the coating. The main tube (thick portion) of the artificial blood vessel used was 16 mm, and the side tube (branch) was 8 mm. Separately from the above, the coating was applied in a circle having a diameter of 5 mm around the crotch point P shown in FIG. The side tube (branch tube) of the T-shaped vascular prosthesis of FIG. 6 subjected to the above processing was alternately pulled ten times in the extension direction of the main tube so that the crotch part was opened. Inject bovine blood into this, 280m
It was left under mHg under pressure for 1 hour. As a result, neither blood leakage nor bleeding near the crotch point P was observed.

Comparative Example 4 Example 4 except that the same coating as in Example 4 was not performed.
As a result, remarkable blood leakage was observed mainly around the point P of the crotch.

[0029]

[Brief description of the drawings]

FIG. 1 shows a crotch point P between a branch and a main vessel of a branched artificial blood vessel.
It is the figure which showed the crotch points Q and Q 'between branch pipes, and the direction which applies force with an arrow.

FIG. 2A shows an example of a branched artificial blood vessel in which crotch points P and Q are not right angles. FIG. 2B shows a case where the diameter of the side tube is larger than the diameter of the main tube, and FIG. 2C shows a case where the branch tube is a plurality of branched artificial blood vessels.

FIG. 3 shows a crotch point P in the case of a Y-shaped branched artificial blood vessel.
It is the figure which showed the surrounding coating range with the oblique line.

FIG. 4 is a crotch point P, P ′ of a T-shaped branched artificial blood vessel.
It is the figure which showed the surrounding coating range with the oblique line.

FIG. 5 is a cross-sectional view taken along the line DD of FIG. 4, and a coating range is indicated by a dotted line.

FIG. 6 is a diagram in which hatching indicates the coating range when examining the coating and its effects in Example 3, Comparative Example 3, Example 4, and Comparative Example 4.

Claims (2)

(57) [Claims] In a vascular prosthesis having a branch, a polymer elastic body is coated on at least the range of the diameter of the branch pipe centered on the crotch point between the branch pipes branched from the main pipe or the crotch point at the base of the branch pipe and the main pipe. A branched artificial blood vessel, characterized in that: 2. The branched artificial blood vessel according to claim 1, wherein the elastic polymer is polyurethane or polysiloxane.