JP3145720U - Stent - Google Patents

Abstract

The present invention provides a flexible and integrally manufactured stent manufactured by laser processing.
A stent 1 is formed in a substantially tubular body and is radially expandable from the inside of the tubular body, and includes a first cell group comprising a plurality of first cells 2 connected in the circumferential direction. One tubular unit 3 and a second tubular unit 3 ′ composed of a second cell group in which a plurality of second cells 2 ′ are connected in the circumferential direction are alternately arranged so as to surround the central axis C1 of the stent 1. A part of the opposing cells of the adjacent first and second tubular units 3, 3 ′ are connected by a connecting part 4, and the shape of the first cell and the second cell is the connecting part 4 The above problem is solved by a stent characterized in that it is symmetrical in the axial direction of the stent 1 with the cell of the connecting part 4 being slightly longer than the cell of the non-connecting part.
[Selection] Figure 1

Description

The present invention relates to a stent used for improving stenosis occurring in a living body such as a blood vessel, and more particularly to a highly durable stent manufactured integrally by laser processing.

In recent years, a stent treatment method has been rapidly popularized to restore blood flow by mechanically dilating an arterial lesion that has been narrowed due to the progression of arteriosclerosis using a balloon catheter, and placing a metal stent in the lumen of the arteriosclerosis. It has become.
A stent used for such treatment needs to satisfy the following three requirements. First, the closed stent is placed on a balloon attached to the distal end portion of the balloon catheter and passed through the patient's tortuous artery along a guide wire that has been inserted into the artery in advance. Or to the constriction. Thus, the stent must be flexible in order to pass through the narrow and tortuous artery. Second, the expanded stent must be durable enough to withstand repeated bending stresses due to the heartbeat, with sufficient strength to support the arterial wall and keep the stenosis open. .

Third, when the stent is expanded by inflating the balloon of the balloon catheter, the total length of the expanded stent becomes shorter than the length of the closed state. If the length of the expanded stent is shortened, it may not be possible to cover the lesion according to the treatment plan of the doctor. Therefore, it is desirable that the expanded stent has little change.

As a result of thorough examination of the conventional stent design, the inventors of the present invention disclosed a design disclosed in Patent Documents 1 and 2, that is, as shown in FIG. The cells 10 are connected in the circumferential direction, and a plurality of the cells 10 are arranged so as to surround the central axis C1 of the stent 11 to form the tubular unit 12, and the adjacent cells 10, 10 ′ of the adjacent tubular units 12, 12 ′ The stents connected to each other by a substantially S-shaped connecting portion 14 have an ideal design with uniform flexibility and sufficient strength to maintain the open state of the stenosis. As a result, it has been unexpectedly found that the bent portion 13 constituting the substantially S-shaped connecting portion is rarely cut. In stent treatment, cutting of the bent portion 13 must be avoided. As a result of various investigations on the cutting factors of the bent portion 13, the inventors of the present invention have found that the bending portion 13 is subjected to repeated bending stress applied to the stent inserted into the blood vessel due to the heartbeat, and the connecting portion against this bending stress. We found out that this is caused by a problem in the structure of.
Patent No. 3654627 Patent No. 3663192

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a flexible stent that is easily manufactured by laser processing and can be easily transported through a narrow and winding artery. Another object of the present invention is that it has sufficient strength to support the artery wall and maintain the open state of the stenosis when the stent is expanded, and to withstand the repeated bending stress of the artery caused by the heartbeat. It is to provide an excellent stent.

As a result of examining the structure of the connecting portion of the stent in detail in order to solve the above problems, the inventors of the present invention surprisingly have the durability and flexibility against bending stress by directly connecting the opposing cells of adjacent tubular units. The inventors have found that the performance is dramatically improved and have reached the present invention.

That is, the present invention is a stent 1 that is formed in a substantially tubular body and is radially expandable from the inside of the tubular body, and includes a plurality of first cells 2 connected in the circumferential direction. The second tubular unit 3 ′ composed of the second cell group in which the first tubular unit 3 and the plurality of second cells 2 ′ are connected in the circumferential direction are alternately arranged so as to surround the central axis C1 of the stent 1. A part of the opposing cells of the adjacent first and second tubular units 3, 3 ′ are connected by a connecting portion 4, and the shapes of the first cell 2 and the second cell 2 ′ are as follows: The stent is characterized in that it is symmetrical in the axial direction of the stent 1 with the connecting portion 4 as the center, and the cells of the connecting portion 4 are slightly longer than the cells of the non-connecting portion.

According to the present invention, in a conventional stent in which cells having excellent flexibility and expandability are connected by a substantially S-shaped connecting portion, the substantially S-shaped connecting portion is eliminated, and the relative relationship between adjacent tubular units is reduced. By directly connecting some of the cells to be connected, durability against bending can be improved without impairing flexibility.

FIG. 1 is a plan view showing an example of the stent of the present invention. 2 is an enlarged view showing a bent portion of the stent shown in FIG. 1, FIG. 3 is a plan view showing another example of the stent of the present invention, and FIG. 4 is an enlarged view of the bent portion 5 of FIG. . As shown in FIG. 1, the stent of the present invention is formed in a substantially tubular body, and includes a first tubular unit 3 and a plurality of first cells, each of which includes a plurality of first cells 2 connected in the circumferential direction. The second cell unit is formed by alternately connecting the second tubular units formed of the second cell group in which the two cells 2 ′ are connected in the circumferential direction. 'And have a symmetrical shape. The tubular units 3 and 3 ′ are radially expandable from the inside of the tubular body, and a plurality of cells 2 and 2 ′ are connected in the circumferential direction, and a plurality of these are arranged so as to surround the central axis C1 of the stent 1. Configured. Further, a part of the cells facing each other between the adjacent annular units 3 and 3 ′ are connected by the connecting portion 4 (partial link type), and the cell of the connecting portion 4 is slightly longer than the cell of the non-connecting portion. That is, among the opposing cells 2 and 2 ′, the cells 2 and 2 ′ of the connecting portion are connected to each other, so there is no gap between the opposing cells, but between the cells 2 and 2 ′ of the non-connecting portion. As shown in FIG. 1, a gap is formed between the bent end portions, and the cell of the connection portion becomes longer than the cell of the non-connection portion by a distance corresponding to this gap. ing. This length is usually about 0.1 to 0.3 mm. The presence of this slight gap prevents cells from overlapping when the stent is bent or contracted, and the opposing cells do not hit when the stent is bent. .

In the present invention, the cell 2 means one structural unit of the pattern constituting the surface of the stent 1, and is bent in a zigzag shape as shown in FIG. 1, and the bent end 5 of the bent portion has a round acute angle shape. is there. The stent 1 shown in FIG. 3 is bent so that all the cells 2, 2 'are parallel.

As the cell 2 becomes obtuse with respect to the central axis C1 after expansion of the stent, the radiation supporting force of the stent becomes larger. As the angle θ after expansion of the bent portion 5 approaches 120 °, the radiation supporting force of the stent increases. That is, in the design of the stent, it is preferable that the angle θ after expansion of the bent portion 5 is designed to be at least 30 ° or more when expanded to at least φ2.5 mm.

In addition, since these are related to the number of cells 2 arranged, the number of cells 2 arranged in the circumferential direction is preferably 4 or more. Further, when the diameter after expansion is φ3.0 mm or more, it is preferable to arrange 6 or more, usually 6 to 12 pieces. In addition, it is preferable that the tubular units 3 and 3 ′ are arranged such that both of the tubular units are combined in the stent axial direction with 6 or more, usually 6 to 12 in number. Furthermore, in the stent axial direction, 3 or more per 10 mm, usually 4 to 8 are arranged, and when the target diameter for stent expansion (standard diameter, eg, φ3.0, φ4.0) is reached, for example, as described above In addition, it is preferable that the angle θ after expansion of the bent portion 5 is designed to be at least 30 ° or more, usually 45 ° to 120 °.

Designing the target diameter to exceed 120 ° is effective for the radiation supporting force of the stent, but causes a problem because the amount of deformation of the bent portion 5 increases. In addition, the shortening of the total length of the stent (four shortening) accompanying expansion becomes large, which causes problems such as difficulty in positioning during stent placement, which is not preferable.

The strut shape of the cell 2 is formed in a symmetric shape in the radial direction as shown in FIG. 6 with respect to the center line C1 in the stent axial direction. Further, in the stent 1, the thickness of the cell is usually constant. In a stent made of a cobalt chromium alloy, the cell width is usually 90 to 100 μm and the thickness is 70 to 80 μm. In a stent made of stainless steel, the cell width is usually 70 to 140 μm and the thickness is 70 to 140 μm.

In the stent of the present invention, since stress is not concentrated on the connecting portion, the durability can be dramatically improved, and flexibility and expandability are not deteriorated, and the conventional stent pattern can be used as it is. There is. In addition, since no connection portion is provided in each cell, even when the diameter of the stent 1 is reduced at the time of delivery to the blood vessel, the cells 2 and 2 'do not overlap each other in the radial direction of the stent.

Further, in the stent 1 illustrated in FIGS. 1 and 2 of the present invention, at least one connecting portion 4 of the cells 2 and 2 ′ constituting each tubular unit 3 and 3 ′ needs to be formed in the circumferential direction of the stent 1. There is. As described above, since the number of cells arranged in the circumferential direction varies depending on the diameter of the stent, the number of connecting portions is selected according to the number of cells. Usually, the diameter of the stent is 3 to 9 mm, and the number of cells is 6 to 10 It is preferable that the number of the connection parts in the case of a piece is 1-3. In the present invention, a connecting portion is formed in a part between a plurality of opposing cells 2 and 2 ′, and the remaining cells 2 and 2 ′ are not connected but form a non-connecting portion. Due to the presence of this unconnected portion, the entire stent 1 becomes more flexible, the delivery performance to the branched blood vessel is improved, and the stress on the arc portion forming the connecting portion is dispersed, so that the connecting portion is continuous without a gap. Thus, the durability is improved as compared with the stent disposed in the same manner.

The stent of the present invention is manufactured by laser processing from metal pipe made of stainless steel such as SUS316, shape memory alloy such as Ni-Ti alloy, Cu-Al-Mn alloy, titanium alloy, tantalum alloy, cobalt chromium alloy, etc. Be done

Next, the manufacturing process by the laser processing method of the stent of the present invention will be described.
First, a tool path in laser processing is created using CAM based on the designed stent shape data. The tool path is set in consideration of the fact that the stent shape can be maintained after laser cutting and that no chips remain. Next, laser processing is performed on the metal thin-film meat tube. Control the generation of burrs and select machining conditions with the goal of high speed and high quality machining.

After the mesh shape is formed by laser cutting, the surface is finished glossy using electropolishing and the edge portion is finished into a smooth shape. In the process of processing a stent made of cobalt chrome alloy, a post-processing process after laser cutting is important. In the stent after laser cutting, the oxide on the metal cut surface is first dissolved with an acid solution, and then electropolishing is performed. In electropolishing, a metal plate such as a stent or stentless is immersed in an electrolytic solution, and the two metals are connected via a DC power source. By applying voltage with the stent side as the anode and the metal plate side as the cathode, the stent on the anode side is dissolved to obtain a polishing effect. In order to obtain an appropriate polishing effect, it is necessary to examine in detail the composition of the electrolytic solution and the applied current conditions.

The stent manufactured by the above laser processing method can form a network structure as designed, so that high flexibility and radiation support force are sufficiently secured, vasodilatability is enhanced, and foreshortening and flare phenomenon are suppressed. A stent in which cells or the like are prevented from being cut can be provided.

Plan view showing an example of the stent of the present invention Enlarged view of Figure 1 Plan view showing another example of the stent of the present invention Enlarged view of Figure 3 Plan view of a conventional stent Conceptual diagram of struts constituting a cell

Explanation of symbols

1 Stent
2,2 'cell
3,3 'tubular unit
4 Connecting part
5 Bending part
C1 ・ ・ ・ Stent central axis

Claims (3)

A stent 1 formed into a substantially tubular body and radially expandable from the inside of the tubular body, the first tubular unit comprising a plurality of first cells 2 connected in the circumferential direction 3 and a second tubular unit 3 ′ composed of a second cell group in which a plurality of second cells 2 ′ are connected in the circumferential direction are alternately arranged so as to surround the central axis C1 of the stent 1, and are adjacent to each other. Part of the opposing cells of the first and second tubular units 3 and 3 ′ are connected by a connecting portion 4, and the shape of the first cell 2 and the second cell 2 ′ is determined by connecting the connecting portion 4 to each other. A stent which is symmetrical in the axial direction of the stent 1 with respect to the center, and the cells of the connecting portion 4 are slightly longer than the cells of the non-connecting portion. 2. The stent according to claim 1, wherein the cell of the connecting portion 4 is 0.1 to 0.3 mm longer than the cell of the non-connecting portion. The stent according to claim 1, wherein 1 to 3 of the opposed cells are connected in the circumferential direction.

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