JP3323132B2 - Stent and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coronary artery, a gastric artery,
Stents to be placed in blood vessels to secure the lumen of stenotic parts of arteries such as the aorta (vascular correction pipes, metal mesh)
And a stent manufactured by the method.

[0002]

2. Description of the Related Art When an obstacle occurs in a blood vessel wall due to some factor, a blood coagulation mechanism starts there, blood coagulates and obstructs blood circulation, and becomes a state called a thrombus, which further obstructs a blood vessel lumen. Reach. When this condition occurs at a bifurcation of the cerebral artery, brain function stops, and when this occurs in the coronary artery of the heart, angina pectoris develops. As a method for treating a thrombus, there is a method called coronary angioplasty as a surgical treatment in addition to a medical treatment such as preventing the formation of a thrombus or dissolving the thrombus with an anticoagulant. In this method, a catheter with a balloon is inserted into the coronary artery to dilate the blood vessel, but there is a high probability that a thrombus will be formed again after the operation. In order to remedy this drawback, a method has been adopted in which a metal tubular support (blood vessel correction pipe), which is now called a stent, is implanted in a thrombus generating portion in a coronary artery.

FIG. 4 and FIG. 5 show a currently used stent and its use. The stent main body is formed by processing a wire of about 0.1 to 0.2 mm in a cage shape like a rhomboid mesh (stent main body 19 in FIG. 4A) or connecting a unit 15 bent in a chain to a pipe shape. A typical configuration (stent body 18 in FIG. 5A) is generally used. All have an outer diameter of about 1.5 to 3 mm and a total length of about 10 to 4
0 mm, flexible in the axial direction so that it can be easily guided along the thrombus, and the outer diameter can be easily adjusted to 3.5 by the internal pressure of the balloon.
Plasticity that can be expanded to about 6 mm and rigidity that does not deform after expansion are required.

[0004]

Since it is implanted in a blood vessel, it may cause a new thrombus formation or rejection due to excessive irritation or damage on the inner wall, or the condition of the inner wall of the stent may obstruct laminar blood flow, Because turbulence and stagnation can cause thrombus, the manufacture of stents
Be very careful. It is not easy to construct a chain-shaped or basket-shaped stent through complicated processes such as bending, knitting, welding, etc., as in the current situation, to meet the above conditions. In addition to these mechanical and physical conditions, chemical issues are also subject to great consideration. That is, in the long term, the deterioration of the material of the stent body and the chemical effect of the stent material on the blood vessel wall, blood, and thrombus are considered. At present, stainless steel is used, but it is in the stage of trial.

It is an object of the present invention to overcome the limitations of the conventional method, to enable easy and mass-produced production, to greatly expand the degree of freedom in length, shape and material in accordance with required conditions, and to insert into blood vessels. In this case, it is an object of the present invention to provide a stent which can be smoothly inserted into a blood vessel and can be easily deformed by following the shape of the blood vessel, and can be uniformly expanded by a balloon after being placed and can reliably maintain the shape. Another object of the present invention is to provide a method for manufacturing a stent by electroforming.

[0006]

The stent according to the present invention to achieve SUMMARY OF for the] said object, predetermined thickness, the length of the stent
On the peripheral surface of the round rod, a non-conductive portion that becomes a certain repeating pattern is formed by printing, and after drying the ink, an electroforming process is performed to apply a metal of a certain thickness to the conductive portion other than the repeating pattern. Electroformed and then pulled out the stainless steel round bar
The remaining metal layer by electroforming is folded back in a U-shape.
And repeat this to form a loop in the circumferential direction
Formed in the axial direction with a large number of pseudo annular units
Shape, repetitive shape hollowed out in a long hole shape, or square shape
By being formed in the shape of a cage having a hollow shape, it can be formed to have an arbitrary length in the axial direction, and when inserted into a blood vessel, it is configured to smoothly follow the shape of the blood vessel and to be deformed. The present invention also provides a method for projecting and exposing a resist and a pattern image on a peripheral surface of a stainless steel rod having a predetermined thickness and length.
Or, by exposing the pattern adhered to the peripheral resist surface, as a part that becomes a certain repeated pattern
The resist is left on the peripheral surface of the stainless steel round bar , and then an electroforming process is performed to electroform a metal of a certain thickness on the conductor portion other than the repetitive pattern, and then the stainless steel round bar is drawn.
The metal layer formed by punching and remaining by electroforming is folded in a U-shape.
And repeat this to create a loop in the circumferential direction.
A large number of formed pseudo-annular units are formed in the axial direction
Shape, repetitive shape hollowed out in a long hole shape, or square
By forming it into a cage-like shape that is hollowed out, it can be formed to have an arbitrary length in the axial direction, and when inserted into a blood vessel, it can be smoothly deformed by following the shape of the blood vessel. The electroformed metal is made of gold.

In order to achieve the above-mentioned other object, a method for manufacturing a stent by electroforming according to the present invention comprises the steps of:
On the peripheral surface of the stainless steel round bar , a printing process of printing and forming a non-conductive portion that becomes a certain repeating pattern, and after drying the ink, performing an electroforming process to perform a certain thickness on the conductive portion other than the repeating pattern. An electroforming step of forming a metal, and thereafter, the stainless steel round bar is pulled out, and the remaining electroformed
The metal layer is folded back in a U-shape, and this is repeated
Pseudo-annular unit with a more circumferential loop
With a large number of holes formed in the axial direction,
In the shape of a cage that is hollowed out in a repetitive shape or square shape
And a drawing step to be constituted. The present invention also provides a stainless steel round bar having a predetermined thickness and length,
Either by performing projection exposure of the resist and the pattern image, or by exposing the pattern adhered to the peripheral resist surface, the stainless
An exposure step of leaving a resist on the peripheral surface of the round bar ; and an electroforming step of performing an electroforming process to form a metal having a certain thickness on a conductor portion other than the repetitive pattern, and thereafter, the stainless steel
The round bar was pulled out, and the remaining metal layer by electroforming was a U-shape.
Fold it back in the shape and repeat it
A large number of pseudo-annular units formed with loops in the axial direction
Formed shape, repetitive shape hollowed out with a long hole shape,
Pulling out into a cage shape that is hollowed out in a square or square shape
Process .

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing a first embodiment of a stent according to the present invention, and is a developed view of a peripheral surface of a cylindrical base metal. For example, printing is performed on a circumferential surface of a stainless steel round bar having a diameter of about 2 to 3 mm so that a portion (a portion having a constant repeating pattern) 2 to be a hole of the product is made into a non-conductive portion. Then, after the ink is dried, an electroforming process is performed with a predetermined metal. As a result, a predetermined metal is electrodeposited on a portion other than the non-conductive portion to have a predetermined thickness. Thereafter, the stainless steel round bar is pulled out, and the remaining electroformed part 1 of the predetermined metal becomes a stent. The stent thus formed has a repetitive pattern excluding the non-conductive portion 2 having a constant repetitive pattern.

The electroformed part 1 shown in FIG. 1 is folded in a U-shape 11-1, 11-2,..., 11-n, and by repeating this, a pseudo ring formed by forming a loop in the circumferential direction. The unit 1a, 1b, 1c, 1d is configured as a unit. Each pseudo annular unit is connected by a connecting portion 3 connecting one U-shaped portion. This is because when inserted into a blood vessel, it can easily bend in any direction without resistance. This is because stainless steel is used as the material of the stent according to the conventional manufacturing method, but as will be described later, no remarkable drawbacks appear in the short term. Since the present invention is manufactured by electroforming, a wide range of materials can be selected. For example, gold, which is most stable among metals in coexistence with a living body, can be used.

In this embodiment, a stent in which four pseudo annular units are connected is shown. However, the number of pseudo annular units is arbitrary, and a stent having a length and flexibility according to demand can be formed. be able to. That is, when the stent body needs to have a relatively long overall length, it is difficult to provide flexibility in the axial direction as an integral structure with the conventional manufacturing method, and a single unit having a shaft length of several millimeters is connected, and as a whole, Welding and other means were required to ensure that the implant could be implanted along the curve of the blood vessel. Since the present invention is based on electroforming, arbitrary connection conditions can be easily treated in the process. The number of connecting points between the pseudo annular units may be not only one but also two or more, and is determined by the shape, material, thickness and the like of the used stent. Further, it goes without saying that the pseudo annular unit can be formed in other shapes in addition to the shape shown in FIG.

FIG. 2 is a view showing a second embodiment of the stent according to the present invention, and is a developed view of a peripheral surface of a cylindrical base metal. In this embodiment, a portion (a fixed repetition portion) 5 corresponding to a hole has a long hole shape, and the remaining portion becomes an electroformed portion 7. The electroformed part 7 has a shape in which a long hole is repeatedly cut out.

FIG. 3 is a developed view of the peripheral surface of a cylindrical base metal showing a third embodiment of the stent according to the present invention. In this embodiment, a portion (a fixed repetition portion) 10 corresponding to a hole has a rectangular shape, and the remaining portion is an electroformed portion 9. The electroformed portion 9 has a cage shape.

When the balloon is inserted into a blood vessel and inflated by a balloon, it is desirable that all portions be uniformly enlarged along the axial direction. In FIG. 1, since the shape is the same at any position in the axial direction, the degree of expansion is the same. However, since the shape of the electroformed portion shown in FIGS. 2 and 3 is different between the end portion and the intermediate portion, there is a possibility that the degree of expansion may be non-uniform as compared with FIG. shape,
Since the thickness and the like are related, whether or not to be adopted is determined depending on whether or not an actual use condition is satisfied.

In the above embodiments, the portions 2, 5, and 10 corresponding to the holes can be formed by printing and forming the non-conductive portion on the peripheral surface of the cylindrical base metal. As another method, it can be formed by projecting and exposing a resist and a pattern image on the peripheral surface of a cylindrical base metal, or by exposing a pattern adhered to the resist surface of the base metal.

[0015] A shape similar to the stent manufactured according to the present invention can also be formed by dissolving the metal corresponding to the hole by etching. However, depending on the type of metal, some materials are difficult to dissolve, and many easily dissolvable metals are susceptible to a chemical reaction in a living body. The same is true for other low degrees of freedom. Disposal of the dissolved metal solution has many problems, such as the necessity of equipment for environmental measures, and in reality it is far from the production method by electroforming. .

[0016]

As described above, the present invention is configured as described above, so that the present invention can provide various effects as follows. 1) First, the degree of freedom in selecting the material of the stent is increased.
In the current manufacturing method, the stent is formed into a chain-shaped or basket-shaped structure through a process such as bending, knitting, and welding using an existing stainless steel wire as a material. Products are required to have delicate plasticity, rigidity, physical and chemical compatibility with living organisms, but it is not clear whether products made by the above methods meet all of these many conditions. Problems remain, and stainless steel is used because it has a well-balanced and marked shortcoming in the overall evaluation of workability, mechanical properties, corrosion resistance, etc., and does not appear in the short term.

It is widely known that gold is most stable in coexistence with living organisms. However, it is clear that changing stainless steel to gold without changing the current manufacturing process of the stent is not possible due to the mechanical properties of gold. According to the present invention, a stent having the same shape as that of a stent manufactured by another manufacturing method by electroforming can be easily manufactured by printing or a resist exposure pattern, and a material that is not suitable for a conventional processing method can be used. Therefore, the degree of freedom in material selection can be greatly expanded, and the effect of improving other functions required for products is also great.

2) Next, the degree of freedom of the pattern for forming the shape of the stent and the degree of freedom of the mechanical properties are increased. The stent needs to have plasticity that can be easily expanded by the internal pressure of the balloon after being implanted at a desired position in a blood vessel, and rigidity that does not deform after expansion. For this reason, a simple pipe shape cannot be used, and a stainless wire is used as a material, and it is commercialized by a method such as forming a cage shape through complicated processing means.
According to the present invention, any pattern can be freely selected, so that the mechanical properties of the stent can be adjusted over a wide range. Factors involved in mechanical properties important as a stent, which can be controlled, the thickness of the electroformed layer in addition to the above pattern, hardness, material selection, post-heat treatment and many more, compared to conventional manufacturing methods, It has a high degree of freedom and can easily meet the required conditions.

3) The shape of the stent becomes smooth. Since a stent manufactured by a conventional manufacturing method is formed by bending a wire as a material and knitting or the like, the stent has many irregularities on a blood vessel wall and a surface that comes into contact with a blood flow, and this has an effect on a blood vessel inner wall and a thrombus. It stimulates and induces turbulence by interrupting laminar flow to blood. In addition, stagnation may occur in the undercut portion of the wire, which may cause a new thrombus. A step according to the present invention manufactured by electroforming.
As can be seen from the manufacturing process,
The inner surface is smooth, has no irregularities, and has much less influence on the blood vessel wall and blood flow.

Regarding the expected rejection of the living body between the state of the outer surface of the stent and the blood vessel wall or thrombus,
It is a subject for consideration as a future issue. Since the manufacturing method according to the present invention has many degrees of freedom such as the surface condition of the outer surface, the shape of the hole, and the selection of the material, it has an advantage that it can meet a wide range of demands.

[Brief description of the drawings]

FIG. 1 is a developed view of a peripheral surface of a cylindrical base metal showing a first embodiment of a stent according to the present invention.

FIG. 2 is a developed view of a peripheral surface of a cylindrical base metal showing a second embodiment of the stent according to the present invention.

FIG. 3 is a developed view of a peripheral surface of a cylindrical base metal showing a third embodiment of the stent according to the present invention.

FIG. 4 is a view showing a cage-shaped stent currently used and a usage state thereof.

FIG. 5 is a view showing an example of a currently used chain stent.

[Explanation of symbols]

 1, 7, 9 ... Electroformed part 2, 5, 10 ... Part corresponding to hole 3 ... Connection part 6 ... Stent after being pulled out 15, 16, 17 ... Unit 18, 19 ... Stent body

Continuation of front page (56) References JP-A-4-329966 (JP, A) JP-A-1-83865 (JP, A) JP-A-6-181993 (JP, A) JP-A-62-235496 (JP) JP-A-62-1231657 (JP, A) JP-A-5-13461 (JP, U) WO 97/44692 (WO, A1) "Plating textbook" (September 20, 1986), daily publication Published by Kogyo Shimbun, pages 198-199, pages 273-278, "Electroforming Technology and Application" (May 25, 1996), published by Maki Shoten, pages 312-317, pages 329-352 (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 1/02 A61M 29/00

Claims (5)

(57) [Claims] 1. A non-conductive portion having a predetermined repetitive pattern is formed by printing on the peripheral surface of a stainless steel round bar having a predetermined thickness and length, and after drying the ink, an electroforming process is performed to perform the repetition. A metal of a certain thickness is electroformed on a conductor part other than the pattern, and then the stainless steel round bar is pulled out, and the remaining electroformed metal layer is folded back in a U-shape.
By repeating this, a loop is formed in the circumferential direction
Shape and length of multiple pseudo annular units formed in the axial direction
Repeated shape with a hole shape or square shape
By configuring it into a cage shape that is pulled out, it can be formed to any length in the axial direction, and when inserted into a blood vessel,
A stent characterized in that it can be deformed by smoothly following the shape of a blood vessel. 2. A method in which a resist and a pattern image are projected and exposed on a peripheral surface of a stainless steel round bar having a predetermined thickness and length, or a pattern adhered to the peripheral resist surface is exposed. discarded as part of a constant repetition pattern
The resist was left on the peripheral surface of the stainless steel round bar , and then a metal of a certain thickness was electroformed on the conductor portion other than the repetitive pattern by performing an electroforming process, and then the stainless steel round bar was pulled out and remained. The metal layer by electroforming is folded back in a U-shape,
By repeating this, a loop is formed in the circumferential direction
Shape and length of multiple pseudo annular units formed in the axial direction
Repeated shape with a hole shape or square shape
By configuring it into a cage shape that is pulled out, it can be formed to any length in the axial direction, and when inserted into a blood vessel,
A stent characterized in that it can be deformed by smoothly following the shape of a blood vessel. 3. The stent according to claim 1, wherein said electroformed metal is gold. 4. A printing step of printing and forming a non-conductive portion having a predetermined repetitive pattern on a peripheral surface of a stainless steel round bar having a predetermined thickness and length, and performing an electroforming process after drying the ink. An electroforming step of forming a metal of a certain thickness on the conductor portion other than the repetitive pattern, and thereafter, pulling out the stainless steel round bar and leaving the remaining electrode
The metal layer by casting is folded back in a U-shape, and this is repeated
Pseudo-ring formed by forming a loop in the circumferential direction
The unit is formed in the shape of a large number of units formed in the axial direction.
Repeated or hollowed out cage shape
A method for producing a stent by electroforming, comprising: 5. The method according to claim 1, wherein a peripheral pattern of a stainless steel rod having a predetermined thickness and length is exposed by projecting a resist and a pattern image onto the peripheral surface or by exposing a pattern adhered to the peripheral resist surface. discarded as part of a constant repetition pattern
An exposure step of leaving a resist on the peripheral surface of the stainless steel round bar ; and an electroforming step of performing an electroforming process to form a metal having a certain thickness on the conductor portion other than the repetitive pattern. And remove the remaining
The metal layer by casting is folded back in a U-shape, and this is repeated
Pseudo-ring formed by forming a loop in the circumferential direction
The unit is formed in the shape of a large number of units formed in the axial direction.
Repeated or hollowed out cage shape
A method for producing a stent by electroforming, comprising: