STENT

Abstract: Disclosed is a stent (1) which can be manufactured densely in a simple way for a minimized processing time and which is configured to be pliable according to the crooked configuration of a body lumen without a refraction so that it has an enhanced partial expansion force at the curved portions and is not readily movable at the inserted position in the body lumen, the stent including first unit members and second unit members each having a unit length, wherein the first unit members make a turn in a zigzag fashion in a cycle on the basis of a reference point to form a cylindrical structure and provide a first one-turn (3), and after forming the first one-turn, correspondingly interfere with each other with a phase difference from the first one-turn (3) to form a mesh structure and provide a first two-turn (5), wherein the second unit members regularly cross each other between the first one-turn (3) and the first two-turn (5) to form a mesh structure on the basis of a reference point spaced at a predetermined distance from a point opposing the reference point of the first one-turn.

Description: STENT BACKGROUND OF THE INVENTION (a) Field of the Invention The present invention relates to a stent and, more specifically, to a stent which can be manufactured densely in a simple way with a minimized processing time and which is configured to be pliable according to the crooked configuration of a body lumen without refraction so that it has an enhanced partial expansion force at the curved portions and is not readily movable at the inserted position in the body lumen. (b) Description of the Related Art It generally appears that a narrowed lumen due to, for example, esophagostenosis from cancer of the esophagus or arteriosclerosis results in poor circulation of blood. In such a case, a stent is inserted into the narrowed lumen as a means for expanding the narrowed passage of the lumen and maintaining the expanded position for the purpose of improved circulation of the blood or articles of diet. The stent generally has a self-elastic cylindrical structure that is constricted under external forces and takes an expanded position by itself when it is left in an unloaded condition free of the external forces. In order to function properly, those stents that take an expanded position by themselves have to possess certain properties, for example, the ability to expand the lumen with a force, enabling successful flexible implantation according to the crooked configuration of the body lumen and the ability to remain fixed at the inserted position in the body lumen. An exemplary self-expandable stent is of a wall type that is disclosed in U.S. Patent No. 4,655,771. The wall-type stent comprises a flexible tubular body which has a diameter that is variable by axial movement of the ends of the body relative to each other and which is composed of several individual rigid but flexible thread elements each of which extends in a helix configuration with the central line of the body as a common axis. The body comprises first elements having the same direction of winding but being axially displaced relative to each other, and second elements crossing the first elements. The second elements are axially displaced relative to each other but have an opposite direction of winding. Another exemplary self-expandable stent is of a heiix-type that is provided with filaments having a unit length and which wind around the cylindrical wall surface of the stent in a helix configuration. The filaments reciprocate in a zigzag fashion between both ends of the stent and cross each other to form a cylindrical mesh structure. SUMMARY OF THE INVENTION In regard to the wall-type stent, which is composed of thread elements each extending in a helix configuration with the central line of the body as a common axis and reciprocating between both ends of the body, the manufacturing performance deteriorates with a longer manufacturing time and the productivity lowers as the denseness of the stent increases. The wall-type stent is flexible so as to be constricted in a very small diameter and readily bent at the curved portions of the body lumen, but it is greatly deteriorated because of the partial expansion force at the curved portions according to the crooked configuration of the body lumen, and is readily moved from the inserted position in the body lumen. Meanwhile, the helix-type stent is also excellent in flexibility so as to be constricted in a very small diameter, but due to such good flexibility, is readily movable from the implanted position in the body lumen and it is hard to manufacture densely. Furthermore, the helix-type stent has a great deterioration because of the partial expansion force at the curved portions according to the crooked configuration of the body lumen, so that much refraction appears at the curved portions. It is therefore an object of the present invention to solve the problems and to provide a stent which can be manufactured densely in a simple way in order to minimize processing time and which is configured to be pliable according to the crooked configuration of a body lumen without refraction so that it has an enhanced partial expansion force at the curved portions and is not readily movable at the inserted position in the body lumen. In one aspect of the present invention, there is provided a stent which comprises first unit members and second unit members each having a unit length, wherein the first unit members make a turn in a zigzag fashion in a cycle on the basis of a reference point to form a cylindrical structure and provide a first one-turn, and after forming the first one-turn, correspondingly interfering with each other with a phase difference from the first one-turn to form a mesh structure and provide a first two-turn, wherein the second unit members regularly cross each other between the first one-turn and the first two-turn to form a mesh structure on the basis of a reference point spaced at a predetermined distance from a point opposing the reference point of the first one-turn and with a phase difference from the first one-turn, and make a turn in a zigzag fashion to provide a second one-turn, wherein the second unit members, after forming the second one-turn, correspondingly interfere with each other with a phase difference from the second one-turn to form a mesh structure, regularly cross each other between the first one-turn and the first two-turn to form a mesh structure, and make a turn in a zigzag fashion to provide a second two-turn. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention: FIG. 1 is a front view of a stent according to a first embodiment of the present invention; FIG. 2 is a development diagram of the stent according to the first embodiment of the present invention, in which first unit members make two turns; FIG. 3 is a development diagram of the stent according to the first embodiment of the present invention, in which second unit members make two turns; FIG. 4 is a development diagram of the stent according to the first embodiment of the present invention, in which the first and second unit members make several turns and combine together; and FIG. 5 is a front view showing a stent according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following detailed description, only the preferred embodiment of the invention has been shown and described, simply by way of illustration of the best mode contemplated by the inventor(s) of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive. Referring to FIGS. 1 to 4, a stent 1 according to a first embodiment of the present invention comprises first and second unit members each of which have a unit length and flexibly expand by themselves. The first unit members are longitudinally arranged at regular intervals with a predetermined width along a base circumference so as to form a cylindrical structure and make a turn in a zigzag fashion in a predetermined cycle on the basis of a reference point (X1-X1 , Y1-Y1) to provide a first one- turn 3. Following the first one-turn 3, as shown in FIG. 2, the first unit members interfere with each other in correspondence to the bending points of the first one-turn 3 with a phase difference from the first one-turn 3 to form a mesh structure and make a turn in a zigzag fashion to provide a first two- turn 5. The second unit members are longitudinally arranged at regular intervals in a predetermined width along the same circumference as the first unit members so as to form a cylindrical structure. The second unit members have a reference point (X2-X2, Y2-Y2) spaced at a predetermined distance from a point opposing the reference point of the first one-turn 3 in the longitudinal direction. The second unit members regularly cross each other between the first one-turn 3 and the first two-turn 5 with a phase difference from the first one-turn 3 to form a mesh structure and make a turn in a zigzag fashion to provide a second one-turn 7. Following the second one-turn 7, the second unit members interfere with each other in correspondence to the bending points of the second one- turn 7 with a phase difference from the second one-turn 7 to form a mesh structure and regularly cross each other between the first one-turn 3 and the first two-turn 5 to form a mesh structure. As such, the second unit members make a turn in a zigzag fashion to provide a second two-turn 9. Preferably, the first one-turn 3, the first two-turn 5, the second one- turn 7 and the second two-turn 9 have the same width W based on the central lines X1-X1 and X2-X2 each having a width difference W/2, and the same cycle with a phase difference so that they are flexibly adapted to the crooked configuration of the body lumen. The first one-turn 3 comprises a plurality of first one-straight lines 11 defined by a plurality of bending points, and a plurality of first one-peaks 13 and first one-valleys 15 which interconnect the first one-straight lines 11. The first two-turn 5 comprises a plurality of first two-straight lines 17 which are defined by a plurality of bending points and cross the first one- straight lines 11 to form a mesh, and a plurality of first two-peaks 19 and first two-valleys 21 which interconnect the first two-straight lines 17 and correspond to the first one-valleys 15 and the first one-peaks 13. The second one-turn 7 comprises a plurality of second one-straight lines 23 which are defined by a plurality of bending points and cross the first two-straight lines 17 to form a mesh, and a plurality of second two-peaks 25 and second two-valleys 27 which interconnect the second one-straight lines 23. The second two-turn 9 comprises a plurality of second two-straight lines 29 which are defined by a plurality of bending points and cross the first one-straight lines 11 , the first two-straight lines 17 and the second one- straight lines 23 to form a mesh, and a plurality of second two-peaks 31 and second two-valleys 33 which interconnect the second two-straight lines 29 and correspond to the second two-valleys 27 and the second two-peaks 33. The first unit members, after forming the first two-turn 5 and prior to the second one-turn 7, form a first connection 35 having at least one twist along the first one-straight lines 11 of the first one-turn 3 and then extend in a helix configuration towards the first one-straight lines 11 of the next first one-turn 3, as shown in FIG. 4. The second unit members, after forming the second two-turn 9 and prior to the first one-turn 3 neighboring the second two-turn 9, form a second connection 37 having at least one twist along the second one-straight lines 23 of the second one-turn 7 and then extend in a helix configuration towards the second one-straight lines 23 of the next second one-turn 7. The first one-peak 13 and the first one-valley 15 of the first one-turn 3 are fixedly interconnected with the corresponding first one-valley 15 and first one-peak 13 of the next first one-turn 3, as shown in FIG. 4. And, the first two-peak 19 and the first two-valley 21 of the first two-turn 5 are fixedly interconnected with the corresponding first two-valley 21 and first two-peak 19 of the next first two-turn 5. The second one-peak 25 and the second one-valley 27 of the second one-turn 7 are fixedly interconnected with the corresponding second one-valley 27 and second one-peak 25 of the next second one-turn 7. The second two-peak 31 and the second two-valley 33 of the second two-turn 9 are fixedly interconnected with the corresponding second two-valley 33 and second two-peak 31 of the next second two-turn 9. Preferably, the first and second unit members are formed from a shape memory alloy, for example, nitinol so that they have an expansion force at a temperature approximate to the temperature of the body lumen. In the stent 1 according to the first embodiment of the present invention, the first one-turn 3, the first two-turn 5, the second one-turn 7 and the second two-turn 9 cross each other between themselves with a predetermined width difference and a predetermined phase difference and interferingly make a turn in a zigzag fashion, while the first one-straight lines 11 , the first two-straight lines 17, the second one-straight lines 23 and the second two-straight lines 29 cross each other to form a mesh structure. Therefore, the stent 1 has very small spaces between the first one- turn 3 and the first two-turn 5 and between the second one-turn 7 and the second two-turn 9 and can be manufactured in a reduced time in a simple way. The first one-peak 13, the first two-peak 19, the first one-valley 15 and the first two-valley 21 are, as shown in FIG. 4, fixedly interconnected with the first one-valley 15, the first two-valley 21 , the first one-peak 13 and the first two-peak 19 neighboring the first one-turn 3 and the first two-turn 5, respectively. As such, the first one-turn 3, the first two-turn 5, the second one-turn 7 and the second two-turn 9 are fixedly interconnected with each other at the respective connections and simply crossed at the respective crossings. The connections and the crossings are alternately positioned along the one circumference of the stent 1 and arranged at regular intervals on the circumference to form a straight line-like configuration. The second one-peak 25, the second two-peak 31 , the second one- valley 27 and the second two-valley 33 are fixedly interconnected with the second one-valley 27, the second two-valley 33, the second one-peak 25 and the second two-peak 31 neighboring the second one-turn 7 and the second two-turn 7, respectively. The first unit members form connections having at least one twist along the first one-straight lines 11 of the first one-turn 3 after forming the first two-turn 5, and the second unit members form connections having at least one twist along the second one-straight lines 23 of the second one-turn 7. Therefore, the stent 1 has such a good expanding property that it can be readily inserted into a narrowed region of the body lumen and it maintains a constant curvature in providing a passage for the body lumen, which prevents refraction and maintains the shape, for example, a cylindrical configuration even when making a sharp curve along the various configurations of the body lumen. FIG. 5 is a diagram showing a second embodiment of the present invention, which is similar to the first embodiment except for the following features. The stent 1 according to the second embodiment of the present invention is coated with a coating 41 , for example, polyurethane, which covers the inner and outer surfaces of the stent 1 to minimize friction between the stent 1 and the body lumen when the stent 1 is expanded in the narrowed region of the body lumen and to allow the blood or articles of diet to readily pass through the body lumen. The coating 41 is warmed at a predetermined temperature and applied to the outer surface of the stent 1 . Alternatively, the stent 1 is immersed in a tank containing the coating 41 and then taken out to cool the coating. The stent 1 has either end or both ends thereof provided with move- preventing members 43 and 44, which have a larger diameter than the stent 1 and support the stent 1 being inserted into the narrowed region of the body lumen to prevent the stent 1 from moving in the body lumen. The move-preventing members 43 and 44 can be of any structure that is wound in the same manner as the stent 1 , or composed of unit members wound in a zigzag fashion in a helix configuration. The move- preventing members 43 and 44 together with the stent 1 are integrally provided with coatings 45 and 46 at the inner and outer surfaces. The move-preventing members 43 and 44 have a center common to the stent 1 so that they are readily expandable when inserted into the narrowed region of the body lumen. As described above, the stent of the present invention can be manufactured densely in a simple way for a minimized processing time to enhance productivity and reduce the manufacturing time. Also, the stent of the present invention is configured to be pliable according to the crooked configuration of a body lumen without refraction so that it has an enhanced partial expansion force at the curved portions and is not readily movable at the inserted position in the body lumen. Thus the present invention successfully provides a passage for the bending narrow portion of the body lumen and allows the blood or articles of diet to readily pass through the lumen. Furthermore, the stent of the present invention is provided with a coating to secure good circulation of the blood or articles of diet and prevent the blood or article of diet from entering other organs. While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims: WHAT IS CLAIMED IS: 1 . A stent comprising first unit members and second unit members each having a unit length, wherein the first unit members make a turn in a zigzag fashion in a cycle on the basis of a reference point to form a cylindrical structure and provide a first one-turn, and after forming the first one-turn, correspondingly interfering with each other with a phase difference from the first one-turn to form a mesh structure and provide a first two-turn, wherein the second unit members regularly cross each other between the first one-turn and the first two-turn to form a mesh structure on the basis of a reference point spaced at a predetermined distance from a point opposing the reference point of the first one-turn and with a phase difference from the first one-turn, and make a turn in a zigzag fashion to provide a second one-turn, wherein the second unit members, after forming the second one-turn, correspondingly interfere with each other with a phase difference from the second one-turn to form a mesh structure, regularly cross each other between the first one-turn and the first two-turn to form a mesh structure, and make a turn in a zigzag fashion to provide a second two-turn. 2. The stent as claimed in claim 1 , wherein the first one-turn and the first two-turn comprise a plurality of first one-straight lines defined by a plurality of bending points, and a plurality of first one-peaks, first two-peaks, first one-valleys and first two-valleys each of which interconnects the first one-straight lines and first two-straight lines, wherein the first one-straight lines cross the first two-straight lines to form a mesh, wherein the second one-turn and the second two-turn comprise a plurality of second one-straight lines and second two-straight lines defined by a plurality of bending points, and a plurality of second one-peaks, second two-peaks, second one-valleys and second two-valleys each of which interconnects the second one-straight lines and the second two-straight lines, wherein the second one-straight lines cross the second two-straight lines to form a mesh, and the second one-straight lines and the second two-straight lines cross the first one-straight lines and the first two-straight lines to form a mesh. 3. The stent as claimed in claim 1 or 2, wherein the first unit members provide a connection having at least one twist along the first one- straight lines of the first one-turn after forming the first two-turn and prior to the second one-turn, wherein the second unit members provide a connection having at least one twist along the second one-straight lines of the second one-turn after forming the second two-turn and prior to the first one-turn neighboring the second two-turn. 4. The stent as claimed in claim 1 or 2, wherein the first one-peak, the first two-peak, the first one-valley and the first two-valley of the first one- turn and the first two-turn are fixedly interconnected with the first one-valley, the first two-valley, the first one-peak and the first two-peak of the first one turn and the first two-turn neighboring the first one-turn and first two-turn, wherein the second one-peak, the second two-peak, the second one-valley and the second two-valley of the second one-turn and the second two-turn are fixedly interconnected with the second one-valley, the second two-valley, the second one-peak and second two-peak of the second one turn and the second two-turn neighboring the second one-turn and second two-turn. 5. The stent as claimed in claim 1 , wherein the stent is coated with a coating for covering inner and outer surfaces of the stent to minimize friction with a body lumen when expanded in the narrowed region of the body lumen and to allow the blood or articles of diet to readily pass through the lumen. 6. The stent as claimed in claim 1 , wherein the stent has either end or both ends thereof provided with a move-preventing member, the move- preventing member having a larger diameter than the stent and supporting the stent inserted into the narrowed region of the body lumen to prevent the stent from moving in the body lumen.

Inventors: KIM SANG-CHUL, LEE GIL-WHAN, LEE GWUI-MUN, KIM, SANG-CHUL, LEE, GIL-WHAN, LEE, GWUI-MUN
Applicants: KIM SANG CHUL, LEE GIL WHAN, LEE GWUI MUN, SEWOONMEDICAL CO LTD, KIM, SANG-CHUL, LEE, GIL-WHAN, LEE, GWUI-MUN, SEWOONMEDICAL CO., LTD.
Application year: 2000
Main classification: A61F2
IPC codes: A61F2