JP4885041B2 - Stent assembly - Google Patents

Description

  The present invention relates to a stent assembly comprising an intravascular stent that is easy to introduce into a tortuous portion of a blood vessel.

  Angioplasty (coronary or general angioplasty) has advanced in the art and has become the most effective means of regenerating stenotic blood vessels. In the early 1980's, angioplasty was first used for coronary clinical methods and has since proven to be an effective alternative to conventional bypass tissue transplantation procedures. Angioplasty utilizing balloon catheters remains the most reliable and practical interventional procedure. Other ancillary techniques, such as laser treatment or directional or rotational arthrotomy, have limited effectiveness, or angioplasty using a balloon to complete the intended procedure Has been found to be either one that uses Restenosis after angioplasty using a balloon is the most serious drawback and is particularly prominent in the coronary artery system.

  Many regimens have been devised to control stenosis, but the degree of success has been limited. Such regimens include laser-based treatment and directional or rotational arthrotomy. However, it is noteworthy that the rate of restenosis after angioplasty is reduced by intravascular stent implantation. Intravascular stent implantation procedures typically use balloon angioplasty to pre-expand the target vessel, then deploy the stent and expand the stent to support the expanded vessel wall from within To be.

  Intravascular stents provide splint scaffolding for the lumen of the blood vessel. The splint support of the vessel wall by the stent (a) prevents elastic return of the expanded vessel wall, and (b) prevents residual stenosis of the vessel (typically occurring during balloon angioplasty). (C) keep the diameter of the stented vessel segment slightly larger than the native non-occluded vessel located proximal and distal to the vessel segment, and (d) modern clinical Helps reduce the incidence of restenosis as shown in the data. Following the performance of angioplasty, the rate of restenosis of stent-retained blood vessels is determined by restenosis of blood vessels that have not undergone stent support or have been treated with another method (including drug treatment and other methods described above). It has been found that it is significantly lower than the incidence.

  Another advantage of vascular stent support is the expected reduction in emergency bypass surgery due to angioplasty. Stent support has proven to be effective in some cases in treating impending blood vessels during angioplasty. Stent support can also control and stabilize unstable local intima tears caused by normal actions during angioplasty. In some cases, balloon angioplasty can be successfully patented by stent implantation, even if the vascular lesions are not sufficiently expanded or less than optimal.

  There have been serious anticoagulant problems with stent implantation methods, especially in the coronary arteries early in the development phase. However, anticoagulant technology has evolved since then and has become easier and more effective. Good and easy-to-use regimens (including simple outpatient anticoagulant treatments as such regimens) are constantly being introduced, resulting in shorter hospital stays for patients treated with stents It was.

  An example of a patent related to a conventional stent is Patent Document 1. The stent described in U.S. Patent No. 6,057,054 consists of a series of elongated tubular members that have a plurality of slots disposed substantially parallel to their longitudinal axes. The tubular members are connected to each other by at least one flexible connector member.

  Since the non-expanded tubular member of Patent Document 1 has too high rigidity, its practical use is limited to a short length. In an embodiment of a multi-link design with a flexible connector that connects a series of tubular members together, a long stent cannot travel along a tortuous vessel. Furthermore, the stiffness of the unexpanded stent increases the possibility of damaging the blood vessel during insertion. The shrinkage of the stent during insertion complicates the correct placement of the stent and reduces the area that the expanded stent can cover. Furthermore, there is no way to program the stent diameter along its longitudinal axis to obtain a tapered expanded stent, and no method is provided for reinforcing the end or other region of the stent.

  Another example of a patent relating to a conventional stent is US Pat. The stent described in U.S. Patent No. 6,057,049 is formed of a patterned tube, which has first and second serpentine patterns. The even-numbered and odd-numbered winding patterns are 180 ° out of phase, and the odd-numbered pattern occurs between every second even-numbered pattern. The second winding pattern extends perpendicular to the first winding pattern along the axis of the tube.

  Adjacent first serpentine patterns are connected to each other by a second serpentine pattern to form a uniform distribution pattern as a whole. Due to the symmetrical configuration with the first and second tortuous patterns with steep right-angle bends, the vessel wall is trapped during delivery. In addition, large turns in the second tortuous pattern are not completely straightened during expansion, reducing the stiffness and structural strength of the expanded stent. Further, there is no way to program the stent diameter along its longitudinal axis to obtain a tapered design stent, and no method is provided to reinforce the end or other region of the stent.

  Conventional and other designs of these and other designs have various disadvantages to some degree. As such disadvantages, (a) the non-expanded stent has a high columnar rigidity and cannot adapt to the bent portion of the blood vessel, and (b) the structural strength of the non-expanded stent in the radial and axial directions. (C) the stent shrinks significantly during expansion, (d) the length of the stent is limited, (e) the expansion stent has a constant diameter, and (f) the crimping characteristics. (G) the change in the surface of the unexpanded stent is rough.

There is a need for a stent with sufficient longitudinal flexibility to be able to travel through a tortuous vessel in an unexpanded state. Further, there is a need for a stent that is structurally strong in an unexpanded state so that the risk of damage or distortion during delivery is minimized. There is a further need for a stent that maintains substantially the same longitudinal length during expansion so that the coverage at the target site can be increased and proper placement of the stent can be easily performed. There is a further need for stents that are designed with longitudinal flexibility to allow long stents up to 100 mm to be safely delivered into tortuous vessels. There is a need for a stent that can be expanded to a variable diameter along the length of the stent so that a taper can be applied to the expanded stent, thereby matching the native tapered shape of the target vessel. (I) Can be firmly crimped onto the dilatation balloon in a thin (low profile) state and in a flexible state, and (ii) crimped onto the delivery catheter to prevent catching on the vessel wall during delivery And (iii) at the end or middle, or both, so as to maintain the end of the stent in fixed contact with the vessel wall of the target vessel. There is a need for a stent with a reinforcing ring.
US Pat. No. 5,102,417 International Publication No. WO96 / 03092 Pamphlet

Accordingly, it is an object of the present invention to provide a splint support means for the lumen of a blood vessel.
Another object of the present invention is to provide a stent that prevents vascular rebound after angioplasty.

Another object of the present invention is to provide a stent that keeps the vessel lumen large compared to results obtained using only balloon angioplasty.
Another object of the present invention is to provide a stent that reduces the shrinkage of the stent length when expanded.

Another object of the present invention is to provide a stent with increased flexibility when delivered to a selected site within a blood vessel.
Another object of the present invention is to provide a low profile stent when crimped onto the delivery balloon of the stent assembly.

It is another object of the present invention to provide a stent that reduces vessel wall damage.
It is another object of the present invention to provide a chain mesh stent that reduces “trapping” to blood vessels in tortuous or curved blood vessels.

The above objective is accomplished by providing a stent assembly having a balloon and an expandable stent disposed outside the balloon. In such a stent assembly, the stent has a first expansion strut. The plurality of first expansion struts form a first expansion column. A plurality of second expansion struts form a second expansion column. A plurality of first connecting struts form a first connecting strut column. Each first expansion strut of the first expansion column is coupled to a second expansion strut of the second expansion column. The first connecting strut has a proximal end coupled to the distal end, and at least a portion of the first connecting strut has a first straight portion and a first tilt angle.
The present invention also relates to a stent assembly comprising a balloon and an expandable stent provided outside the balloon, wherein the stent forms an expansion column with a plurality of expansion struts arranged in the circumferential direction. It is formed by connecting a plurality of expansion columns in the length direction of the stent, and an expansion column from any expansion column to the distal end side in the length direction of the stent. The width is removed, and the removed width increases with the expansion column at the distal end, and the diameter of the stent becomes tapered with a smaller diameter toward the distal end , and the balloon can be used for use with a tapered stent. It is characterized by having a tapered geometric shape .

  A first embodiment of the present invention is shown in FIGS. 1A, 1B, 1C, 2A and 2B. Referring to FIG. 1A, an elongate hollow tubular stent 10 is shown in a non-tensioned state. The proximal end 12 and the distal end 14 define a longitudinal length 16 of the stent 10. The longitudinal length 16 of the stent 10 may be as long as 100 mm or more. The proximal opening 18 and the distal opening 20 communicate with the lumen 22 of the stent 10. The stent 10 may be a single piece without seams or weld joints, or it may consist of multiple pieces.

  The stent 10 is comprised of 2-50 or more expansion columns or rings 24 connected to each other by interspersed connecting strut columns 26. The first column of the proximal end 12 of the stent 10 and the last column of the distal end 14 are expansion columns 24.

  The expansion column 24 is formed by a series of expansion struts 28 and joint struts 30. The expansion strut 28 is a thin and elongated member configured to extend at least partially in the direction of the longitudinal axis of the stent 10. When an outward external force is exerted on the stent 10 from the inside by a dilatation balloon or other means, the dilatation struts 28 become more circumferential, ie along the surface of the cylindrical stent 10 and its longitudinal axis. The direction changes so as to extend perpendicularly to. By changing the orientation of the expansion struts 28, the stent 10 has an expanded circumferential length and diameter. In FIG. 1A, the expansion struts 28 of the unexpanded stent 10 appear to extend substantially parallel to the longitudinal axis of the stent 10.

  The expansion struts 28 are joined together by joint struts 30 to form a plurality of expansion strut pairs 32. The expansion strut pair has a closed end 34 and an open end 36. Additional joining struts 30 join the expansion struts 28 of adjacent expansion strut pairs 32 to each other, and the expansion struts 28 are alternately joined to the adjacent expansion struts 28 at their proximal and distal ends to expand the expansion column. 24 is formed. Each expansion column 24 has a plurality, typically 8-20, 20-60 or more expansion struts 28.

  Connecting struts 38 connect adjacent expansion columns 24 together to form a series of scattered connecting strut columns 26 that each extend around the circumference of the stent 10. Each connecting strut 38 joins a pair of expansion struts 28 in the expansion column 24 to a pair of adjacent expansion struts 28 in the adjacent expansion column 24. For the stent 10 of FIG. 1A, the ratio of the number of expansion struts 28 in the expansion column 24 to the number of connection struts 38 in the connection strut column 26 is 2: 1, but this ratio is typically x: 1. , Where x is greater than or less than 2. Furthermore, the stent 10 of FIG. 1A begins with an expansion column 24 at the proximal end 1 and ends with an expansion column 24 at the distal end 14 so that there are n expansion columns 24 present per column. If the number of struts 28 is m, the number of connected strut columns 26 will be (m−1) and the number of connected struts 38 will be n (m−1) / 2.

  By reducing the number of connection struts 38 in each connection strut column 26 compared to the expansion struts 28 in each expansion column 24, the stent 10 can be flexible in the longitudinal direction. To further increase longitudinal flexibility, use narrow connecting struts and additional flexibility and flexibility to the stent as it moves around the bend in the native vessel give.

  At least part of the open space between the struts of the stent 10 forms an asymmetric cell space 40. The cell space is an empty area on the surface of the stent 10 that is completely surrounded by one or a combination of stent struts including expansion struts 28, connecting struts 38 or joint struts 30. The asymmetric cell space 40 has no geometric symmetry, that is, rotationally symmetric, linearly symmetric, rotationally and linearly symmetric, or other symmetric. That's not true.

  The asymmetric cell space 40 of FIG. 1A includes a first expansion strut pair 32 of a first expansion column 24, a first connecting strut 38, a second expansion strut pair 32 of an adjacent expansion column 24, a first joint strut. 30, a second connecting strut 38 and a second joint strut 30. Furthermore, the expansion strut pairs 32 of the asymmetric cell space 40 should be circumferentially spaced, i.e. have a longitudinal axis that is not collinear and have opposite open ends 36. . The space between the two expansion struts of the expansion strut pair 32 is called the loop slot 42.

  FIG. 1B shows the lumen 22, radius 44 and stent wall 46 of the stent 10. The stent wall 46 comprises a stent strut including an expansion strut 28, a connecting strut 38 and a joint strut 30.

  FIG. 1C shows the proximal end 12, distal end 14, longitudinal length 16, lumen 22 and stent wall 46 of the stent 10. The lumen 22 is surrounded by a stent wall 46 that forms the cylindrical surface of the stent 10.

  2A and 2B, the joint strut 30 of the stent 10 appears to extend at an angle with respect to the expansion strut 28 and is at a small angle with one expansion strut 28 in the expansion strut pair 32. 48 and a large angle 50 with the other expansion struts 28 of the expansion strut pair 32. The small corner 48 is 90 ° full and the large corner 50 is greater than 90 °. The joining struts 30 extend longitudinally along the longitudinal axis of the stent 10 and circumferentially along its surface perpendicular to the longitudinal axis of the stent 10.

  The expansion strut spacing 52 between adjacent expansion struts 28 in a given expansion column 24 is constant for the stent 10 of FIGS. 2A and 2B, but non-constant spacing may be used. The expansion strut separation distance 52 may vary, and for example, the separation distance 52 between adjacent expansion struts 28 in the expansion column 24 may alternate between a small separation distance and a large separation distance. Further, the separation distance 52 within a single expansion column 24 may be different from other separation distances 52 of other columns 24.

  It is noted that changing the expansion strut separation distance 52 that forms the loop slot 42 results in a change in the width of the loop slot. Further, the longitudinal axis of the loop slot 42 need not be collinear with or parallel to the longitudinal axis of the loop slot 42 of the adjacent expansion column 24. 2A and 2B show the arrangement of the expansion struts 28 such that the loop slots 42 located on the same straight line and the adjacent loop slots 42 parallel to each other are formed. A loop slot 42 which is not parallel and is not parallel can also be used.

  Further, the shape of the loop slot 42 need not be the same throughout a loop lot of single or multiple expansion columns 24. Changing the shape of the loop slot 42 involves changing the orientation or physical dimensions of the expansion strut 28 and / or the joining strut 30 that interconnects the expansion struts 28 of the expansion strut pair 32 that define the boundary of the loop slot 42. Good.

  The connecting struts 38 connect adjacent extension columns 24 to each other by connecting the distal ends of the extension strut pairs in one extension column 24 to the proximal ends of adjacent extension strut pairs 32 in the second extension column 24. is doing. The connecting strut 38 of FIGS. 2A and 2B is formed of two straight portions, the distal end of the first straight portion 54 is joined to the proximal end of the second straight portion 56, and the first inclined angle 58 is formed. Is formed.

  The first straight portion 54 of the connecting strut 38, the joint strut 30, is joined to the expansion strut 28 at a location that makes a small angle 48 with the expansion strut 28. The first straight portion 54 extends substantially collinearly to the joining strut 30 and continues the line of joining strut 30 into the space between the expansion columns 24. The distal end portion of the first straight portion 54 is joined to the proximal end portion of the second straight portion 56 to form an inclination angle 58. The second straight portion 56 extends substantially parallel to the expansion strut 28 and its distal end is connected to the joining strut 30 in the adjacent expansion column 24. The distal end of the second straight portion 56 is attached to the expansion strut 28 at a point where the joining strut 30 makes a small angle 48 with the expansion strut 28. Further, the joint strut 30 may have the same width as the first tilt angle or may have a different width and second tilt angle.

  2A and 2B show the connecting struts 38 and the joining struts 30 tilted with respect to the longitudinal axis of the stent 10, and the circumferential orientation of these tilted struts is from one column to the next. Alternating. The circumferential direction is the winding direction of the inclined struts around the surface of the stent 10. The direction of inclination of the first straight portion 4 of the connecting strut in the connecting strut column 26 in the circumferential direction is determined by the inclination of the first straight portion 54 of the connecting strut in the adjacent connecting strut column 26 in the circumferential direction. It is the opposite of direction. Similarly, the direction of inclination of the joining strut 30 in the extension column 24 in the circumferential direction is opposite to the direction of inclination of the joining strut 30 in the adjacent extension column 24 in the circumferential direction. By alternating the direction of inclination of the connecting struts 38 in the circumferential direction and the direction of inclination of the connecting struts 30 in the circumferential direction, axial warping of the stent 10 during delivery and expansion is prevented. Other inclined orientation patterns that are not alternating for the connecting struts 38 or the joining struts 30 or both may be used.

  3A and 3B are schematic diagrams showing the stent of the present invention in an unexpanded state and an expanded state, respectively. The stent is shown by design as a flat projection image as if the stent 10 had been cut longitudinally parallel to its longitudinal axis and flattened. The connecting strut 38 consists of a first straight portion 54 and a second straight portion 56 that form an inclination angle 58 at the pivot point 60. An asymmetric cell space 40 is formed by the expansion strut pair 32, the connecting strut 38 and the joint strut 30. A large number of entangled asymmetric cell spaces 40 constitute a design pattern.

  When the stent is expanded (see FIG. 3B), the expansion strut pairs 32 expand at their open ends 36, and the length of the expansion struts 28 decreases along the longitudinal axis of the cylindrical stent. In contrast to the longitudinal shortening of the expansion strut 28 during expansion, the connecting strut 38 extends in the longitudinal direction. When the inclination angle 58 increases during expansion, the connecting struts 38 become straight and the distance between the coupled expansion strut pairs 32 increases. As the distance between the coupled expansion strut pairs 32 increases, the longitudinal shortening of the expansion struts 28 is substantially compensated. Thus, the stent has a substantially constant longitudinal length in the unexpanded and expanded states.

  As the stent expands, each expansion column 24 is stretched circumferentially, increasing the space between the struts. The stent 10 is provided with high radial support strength by connecting the expansion columns 24 to each other by connecting struts 38 that are straightened during the expansion phase. As the entire stent 10 expands, it is coupled to a continuous chain mesh consisting of stretched expansion columns 24 and connecting strut columns 26, which are asymmetric interlaced cells that resist both axial and radial collapse. A geometric shape is formed. As the stent expands, the stiffness and fatigue tolerance of the stent increases.

  In addition, the effective bending and straightening of the connecting struts 38 at the pivot point 60 can increase the longitudinal flexibility of the stent. In order to bend the stent longitudinally, at least some of the connecting struts 38 bend in their tangential plane. The tangent plane of a particular connecting strut 38 refers to the plane that substantially contacts the cylindrical surface of the stent at that connecting strut 38. The width of the connecting struts 38 is typically 2-4 times greater than the thickness, which makes the connecting struts 38 relatively inflexible when bent in their tangential plane. However, the pivot point 60 of the connecting strut 38 provides a flexible joint to the connecting strut 38 that is more flexible and increases flexibility in the longitudinal direction of the stent.

  4A and 4B, a first embodiment of the stent 10 of the present invention is shown. In this variation, the stent 10 has a length 16 of 33.25 mm and a perimeter length 88 in the uncompressed and unexpanded state of 5.26 mm. Interstitial strut columns 26 are interspersed between the 15 expansion columns 24. Each expansion column 24 consists of 12 expansion struts 28 joined alternately at the proximal and distal ends by joint struts 30 forming six expansion strut pairs 32. The expansion struts 28 are aligned parallel to the longitudinal axis of the cylindrical stent 10. The joint strut 30 forms a small angle 48 and a large angle 50 with each expansion strut 28 of the expansion strut pair 32.

Adjacent expansion columns 24 employ joint struts 30 in which the inclination directions in the circumferential direction are alternated.
In this variation of the first embodiment, the expansion strut width 62 is 0.20 mm, the expansion strut length 64 is 1.51 mm, and the connecting strut width 66 is 0.13 mm. The distance 68 from the outer edge of the first expansion strut 28 in the same expansion column 24 to the outer edge of the second adjacent expansion strut 28 is 0.64 mm, leaving a loop slot width 70 of 0.24 mm. ing.

In this modification of the first embodiment, the connecting strut 38 is obtained by joining the first inclined linear portion 54 to the second linear portion 56 at an inclination angle 58.
The first straight portion 54 is slightly longer than the second straight portion 54, and its proximal end is attached to the expansion strut 28 in the expansion column 54. The proximal end of the first straight portion 54 is attached to the expansion strut 28 at a point where the joint strut 30 forms a small corner 48 with the expansion strut 28. The first straight portion 54 extends substantially collinearly with the joining strut 50, and its distal end is attached to the proximal end of the second straight portion 56 to form an inclined angle 58. The second straight portion 56 extends substantially collinearly with respect to the expansion strut 28 and its distal end is attached to the expansion strut 28 of the adjacent expansion column 24. Such attachment is performed where the expansion strut 28 forms a small corner 48 with the joining strut 30. The joining struts 30 and the first linear portions 54 are inclined with alternating circumferential directions between adjacent columns.

  The joining of the connecting strut 38 and the expansion strut 28 at the point where the small angle 48 is formed makes the surface of the non-expanded stent streamlined and minimizes the points where it can be trapped. Helps 10 smooth delivery. Thus, as a result of the bare delivery of the stent 10 to the target site in the blood vessel, snags are minimized when the stent 10 is advanced through the bends and bends in the blood vessel. become. The stent 10 behaves like a flexible tubular sledge when moving back and forth in a blood vessel while attached to a delivery catheter, with a tortuous blood vessel and vessel lumen. It slides over the bumps of irregular size caused by plaques due to internal atherosclerosis.

  The stent 10 of FIGS. 4A and 4B, when fully expanded, has an inner diameter of up to 5.0 mm while maintaining an acceptable level of radial support strength and fatigue tolerance. The outer diameter of the crimped stent should be as small as 1.0 mm or less depending on the conditions of the delivery balloon profile located below it. It is particularly important that the outer diameter in the crimped state is small if stent delivery is attempted without pre-expansion of the target site. When the stent is optimally crimped onto the delivery balloon, the surface of the crimped stent is smooth, and the stent does not become caught during advancement or retraction in the blood vessel.

  FIG. 5 shows a second embodiment of the present invention in which the expanded stent 10 tapers from the proximal end 12 to the distal end 14. The shaded segments 72, 74, 76, 78, 80, 82, 84 of the expansion strut 28 represent the area of the expansion strut 28 to be removed. Removal of the shaded segments 72, 74, 76, 78, 80, 82, 84 causes the stent 10 to be gently tapered when expanded, with the distal end 14 being more proximal than the proximal end 12. Has a small expanded diameter. The degree of contraction of the expanded diameter of the stent 10 at a given expansion column 24 is proportional to the length of the removed segment 72, 74, 76, 78, 80, 82 or 84 at that expansion column 24. I will. In the expansion stent 10, the shortened expansion strut 28 has a shortened component along the circumference of the stent, resulting in a decrease in circumferential length and diameter. The tapered diameter portion may be positioned somewhere along the length of the stent 10, and a moderate degree of expansion strut 28 in a given expansion column 24 can be used to make the taper shape somewhat loose. Larger or smaller parts should be removed. Taper is especially important for long stents of 12 mm or longer. This is because the blood vessel taper is more pronounced over longer lengths. Long stents with a constant stent diameter can only match the diameter of the target vessel over a short area. If the proximal vessel size matches the stent diameter, the expanded end of the stent will be too large for the native vessel, and stent expansion may cause intimal dissection of the distal vessel. On the other hand, if the size of the distal vessel matches the stent diameter, the proximal end of the expanded stent will be too small to be set inside the vessel lumen. Accordingly, it is desirable to provide a stent with a tapered expanded diameter.

  Another way to achieve a tapered expandable stent is to change the stiffness of the joint struts so that the strut stiffness varies along the length of the stent. . To change the stiffness of the struts, change the length, width or thickness, add stiffening material, change the physical properties of the stent material using chemical or mechanical means, or around the stent One or a series of elastic elements.

  Ideally, a tapered balloon catheter matched to this should be used in order to use a tapered diameter stent and to deliver and deploy the tapered diameter stent. Methods using a matched tapered balloon catheter used with a tapered diameter stent are within the scope of the present invention.

  Also, expanding a non-tapered stent using a tapered balloon will result in a tapered expanded stent, but since the metal is not removed from the stent, the stent is tapered as a result of incomplete expansion. Make. Therefore, the stent has more metal fraction at the tapered end, resulting in a higher risk of acute thrombosis. Metal fraction is the percentage of the surface of the expanded stent that is covered with stent strut material. By shortening the expansion strut as shown in FIG. 5, a taper expansion stent with a substantially constant metal fraction along its length is obtained.

  The third embodiment of the present invention shown in FIGS. 6A and 6B has a number of reinforced expansion columns 86 disposed along the length of the stent 10. Reinforcing column 86 is positioned along the length of the stent and provides additional local radial support strength and stiffness to stent 10. Additional strength and stiffness are particularly important at both ends of the stent in preventing stent deformation both during delivery and after deployment. During delivery, the stent end can be caught on the vessel wall, possibly deforming the unexpanded stent and changing its expansion characteristics. After placement of the stent, it is important that the ends of the stent be rigid so that they remain firmly in contact with the vessel wall, otherwise, during subsequent catheter manipulation procedures, Alternatively, a guide wire may be caught at the end of the suntet and pull the stent away from the vessel wall, possibly damaging or occluding the vessel.

  A particular variation of the third embodiment of the stent 10 shown in FIGS. 6A and 6B has a length 16 of 20.70 mm and a non-crimp and non-expanded peripheral length 88 of 5.26 mm. The stent 10 consists of six expansion columns 24 and three reinforcing expansion columns 86, each of which consists of twelve expansion struts 28 or reinforcing expansion struts 90, respectively. One reinforcing expansion column 86 is disposed at each end and one along the length of the stent 10. The expansion strut width 62 is 0.15 mm, the reinforced expansion strut width 92 is 0.20 mm, and the connecting strut width 66 is 0.10 mm. The small angle 48 formed by the joint strut 30 and the expansion strut 28 is 75 °, and the small angle 94 formed by the reinforcement joint strut 96 and the reinforcement expansion strut 90 is 60 °.

  Other arrangements of reinforced expansion struts 86, such as reinforced expansion columns 86, may be provided only at both ends of the stent, only at one end, or at multiple locations throughout the length of the stent, and this is within the scope of the present invention. . Alternatively, tapering may be programmed into the reinforced stent 10 by shortening the expansion struts 28 and reinforcing expansion struts 90 in the appropriate expansion columns 24,86.

  The fourth embodiment of the present invention shown in FIGS. 7A, 7B and 7C is similar to the third embodiment, but has another feature of relief cuts 98,100. A relief cut is a cut after the metal is removed from the struts, usually at a junction where a number of struts are connected. Providing the relief cuts increases the flexibility of the strut or joint because a thin and narrow area is formed along the strut or joint. A relief cut 98 is formed at the junction formed between the first straight portion 54 of the connecting strut 38 and the expansion strut 28. A relief cut 100 is formed at the junction between the second straight portion 56 of the connecting strut 38 and the expansion strut 28. Placing a relief cut provides additional flexibility to the unexpanded stent. A relief cut may be placed at the other joint and may be incorporated into any of the embodiments described above.

  8A, 8B, 8C, 8D and 8E show several variations of connecting struts that can be used in any of the above-described embodiments. FIG. 8A shows a round loop connection strut 38 joining two circumferentially spaced expansion strut pairs 32 in the adjacent expansion column. The expansion struts 8 of each expansion strut pair 32 are joined together by joint struts 30. The joint struts 30 are inclined to form a small angle 48 and a large angle 50 with the expansion struts 28 to which they are connected. A round loop connecting strut 38 is connected to the expansion strut 28 where a small angle is formed between the expansion strut 28 and the joint strut 30. The slope of the round connecting strut 38 at the proximal end 102 and the distal end 104 substantially matches the slope of the joining strut 30 that connects the pair of expansion struts 28. Thus, the round loop connecting strut 38 is smoothly joined to the joint strut 30. Further, the round loop connection strut 38 has a first radius of curvature 106 and a second radius of curvature 108.

  In the design of FIG. 8B, round loop connecting struts 38 join two circumferentially spaced expansion strut pairs 32 in adjacent expansion columns. The expansion struts 28 of each expansion strut pair 32 are joined to each other by joint struts 30. The joining struts 30 are perpendicular to the expansion struts 28 to which they are connected. The round loop connection strut 38 is connected to the expansion strut 28 at the same location as the joint strut 30. The round connecting strut 38 has a first radius of curvature 106 and a second radius of curvature 108 to connect the circumferentially spaced pairs of expansion struts 32 to each other.

  In the design of FIG. 8C, the connecting strut 38 joins two circumferentially spaced expansion strut pairs 32 in adjacent expansion columns. The expansion struts 28 of each expansion strut pair 32 are joined to each other by joint struts 30. The joint struts 30 are inclined to form a small angle 48 and a large angle 50 with the expansion struts 28 to which they are connected. The connecting struts 38 connect the expansion struts 28 to each other where a small angle 48 is formed between the expansion strut 28 and the joint strut 30.

  The connecting strut 38 is composed of three straight portions 110, 112, 114 that form two inclination angles 116, 118. The proximal end of the straight portion 110 is attached to the expansion strut 28 at a location where the joint strut 30 forms a small angle 48 with the expansion strut 28. The straight portion 110 extends substantially collinearly with respect to the joining strut 30, and its distal end is attached to the straight portion 112 to form an inclined angle 116. The straight portion 112 extends at an angle relative to the straight portion 110 such that the straight portion 112 is substantially parallel to the expansion strut 28, the straight portion 112 having a straight portion at its distal end. An inclination angle 118 is formed by being connected to the base end portion of 114. The straight portion 114 extends at an angle so that it is substantially collinear with the joining strut 30 of the adjacent expansion strut pair 32. The straight portion 114 is attached at its distal end to the expansion strut 28 of the adjacent expansion strut pair 32 at a point where the joint strut 30 forms a small angle 48 with the expansion strut 28.

  In the designs of FIGS. 8D and 8E, the connecting struts 38 join two circumferentially spaced expansion strut pairs 32 in adjacent expansion columns. The expansion struts 28 in each expansion strut pair 32 are joined to each other by joint struts 30. The joint struts 30 are perpendicular to the expansion struts 28 to which they are connected. The connection strut 38 is connected to the expansion strut 28 at the same location as the joint strut 30.

  The connecting struts 38 of FIGS. 8D and 8E are composed of a number of connecting strut portions, which have a number of tilt angles that couple the expansion strut pair 32 to the adjacent expansion strut pair 32. The ends are connected to form a jagged connecting strut 38. The connecting strut of FIG. 8D is composed of three connecting strut portions 120, 122, 124 formed with two inclined angles 126, 128, whereas the connecting strut of FIG. 8E has three inclined angles 138, 140. , 142 are formed of four connecting strut portions 130, 132, 134, 136. In addition, the connecting strut portion 134 has been redesigned by using a connecting strut portion 144 shown in dotted lines in place of the connecting strut portion 136, thereby providing another possible geometric configuration for the connecting strut 38. The shape is obtained.

  Those skilled in the art will appreciate that many arrangements are contemplated for connecting struts and joint struts that fall within the scope of the present invention, and that the above examples are not exclusive.

The stent of the present invention can be used for non-coronary, aortic, and avascular tubular internal organs due to the flexibility of the stent design, but is ideal for coronary applications.
A typical coronary stent has an expanded diameter of 2.5 mm to 5.0 mm. However, stents that have high radial strength and fatigue resistance and expand to a diameter of 5.0 mm may have a stent metal fraction that is high enough to exceed acceptable limits when used on small diameter vessels. is there. If the stent metal fraction is high, thrombosis and restenosis may occur. Even with the same metal fraction, blood vessels with small luminal diameters tend to have a higher incidence of thrombosis than those with large diameters. Therefore, for coronal applications, it is used for at least two different types of stents, namely small diameter vascular stents used for vessels with a diameter of 2.5 mm to 3.0 mm and vessels with a diameter of 3.0 mm to 5.0 mm. It is preferred to provide a large diameter vascular stent. Thus, both small and large vessels, when treated with an appropriately sized stent, will accommodate ideal metal fraction stents similar to each other.

  The stent of the present invention can be manufactured by cutting a stent pattern from a stainless steel tube using a CAM-driven laser cutting system. The coarsely cut stent is preferably electropolished to remove surface defects and sharp edges. Other methods of manufacturing the stent, such as EDM, photoelectric etching or other methods can also be used. Any suitable material can be used as the constituent material of the stent, such materials including other metals and polymers. Provided that these materials have the necessary structural strength, flexibility, biocompatibility and expandability.

  The stent is at least partially plated with a radiopaque metal such as gold, platinum, tantalum or other suitable metal. Although it is preferable to plate only both ends of the stent by the local plating method, the entire stent or other regions may be plated. When plating both ends, 1 to 3 or more expansion columns at each end of the stent are plated to mark both ends of the stent so that they can be identified by fluoroscopy during the stent loading procedure To. By plating the stent only at both ends, interference of the radiopac plating material of the stent frame with performance or surface conditioning properties is minimized. Furthermore, the required amount of plating material is reduced and the material cost of the stent is reduced.

  After plating, the stent is usually cleaned using detergents, saline and ultrasonic means well known in the art. The stent is then inspected for quality control, assembled into a delivery balloon catheter, properly packaged, labeled and sterilized.

  The stent may be sold alone or as a pre-attached delivery balloon catheter assembly as shown in FIG. Referring to FIG. 9, the stent 10 is crimped or crimped onto a folded balloon 146 located at the distal end 148 of the delivery balloon catheter assembly 150. The assembly 150 includes a proximal adapter 152, a catheter shaft 154, a balloon channel 156, a guide wire channel 158, a balloon 146 and a guide wire 160. The balloon 146 may be tapered from the proximal end to the distal end in the expanded state, or may be curved, or may be tapered and curved. Furthermore, the stent 10 may be not tapered or tapered in the expanded state.

  Typically, a guide wire 160 is inserted into a vein or artery and advanced to the target site. The catheter shaft 154 is then advanced along the guide wire to position the stent 10 and catheter 146 in place at the target site. Once in place, balloon 146 is inflated through balloon channel 156 to expand stent 10 from a crimped state to an expanded state. In the expanded state, the stent 10 provides the desired splint support for the blood vessel. Once the stent 10 is expanded, the balloon 146 is deflated and the catheter shaft 154, balloon 146, and guide wire 160 are removed from the patient's body.

  The stent of the present invention may be as short as 10 mm or less, or as long as 100 mm or more. However, when using long stents, a matching length of delivery catheter balloon will generally be required to expand the stent to these deployed positions. Long stents depend on the target vessel, but this deployment may require a long curved balloon. A curved balloon that matches the natural curved state of the vessel reduces the stress on the vessel during stent deployment. This is particularly important for many coronary applications that require stenting within curved coronary vessels. The use of such curved balloons is within the scope of the present invention.

  The foregoing description of the preferred embodiment of the present invention has been made for purposes of illustration. Such description is not exclusive and is not intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that many design changes and modifications can be made. The scope of the present invention is determined based on the description of the claims and the equivalent scope thereof.

The side view which shows the mode before expansion of embodiment of the stent of this invention. Sectional drawing which shows embodiment of the stent of this invention. The longitudinal cross-sectional view which shows embodiment of the stent of this invention. 1 is a schematic diagram showing a strut pattern of an embodiment of the stent of the present invention. FIG. 2B is a development view showing a part of the pattern of FIG. 2A. 1 is a schematic diagram illustrating a pre-expansion mode of an embodiment of the stent of the present invention. 1 is a schematic diagram showing an expanded embodiment of a stent of the present invention. 1 is a schematic diagram showing dimensions of an embodiment of a stent of the present invention. FIG. 4B is a partially enlarged view of the schematic diagram of FIG. 4A. 1 is a schematic diagram illustrating an embodiment of a stent of the present invention with a tapered diameter in a mode after expansion. 1 schematically illustrates an embodiment of a stent of the present invention with a reinforced expansion column. FIG. 6B is a perspective view illustrating the embodiment of FIG. 6A. 1 is a schematic diagram illustrating an embodiment of a stent of the present invention in which a relief cut is formed at a strut joint to increase the flexibility of the strut joint. The elements on larger scale which show embodiment of FIG. 7A. FIG. 7B is an enlarged view showing a single articulated strut joining two expansion strut pairs together in accordance with the embodiment of FIG. 7A. FIG. 3 is a schematic diagram showing another geometric shape of the connecting strut and the joining trat of the present invention. FIG. 3 is a schematic diagram showing another geometric shape of the connecting strut and the joining trat of the present invention. FIG. 3 is a schematic diagram showing another geometric shape of the connecting strut joint strut of the present invention. 4 is a schematic diagram showing another geometric shape of the connecting strut and the joining strut of the present invention. 4 is a schematic diagram showing another geometric shape of the connecting strut and the joining strut of the present invention. 1 is a schematic view of a delivery balloon catheter illustrating a stent delivery method of the present invention.

Claims (6)

With balloons,
A stent assembly comprising an expandable stent provided outside the balloon,
The stent is formed by forming an expansion column with a plurality of expansion struts arranged in the circumferential direction, and connecting a plurality of the expansion columns in the length direction of the stent;
In the length direction of the stent, the expansion column on the distal end side from any expansion column is removed from the circumferential width of the expansion strut in each expansion column, and the removed width becomes larger as the expansion column on the distal end side, The diameter of the stent has a tapered shape with a smaller diameter on the tip side ,
A stent assembly wherein the balloon has a tapered geometry for use with a tapered stent. The stent assembly according to claim 1, wherein a connection strut column is formed by a plurality of connection struts arranged in the circumferential direction, and expansion columns adjacent to each other are connected by the connection strut column. The stent assembly according to claim 1, wherein the proximal end and the distal end of the connecting struts are offset from each other circumferentially when the stent is in an unexpanded state. The stent assembly according to claim 1, wherein the proximal end and the distal end of the connecting struts are offset from each other circumferentially when the stent is in an expanded state. The connecting strut is formed of two straight portions, and a distal end portion of the first straight portion is joined to a proximal end portion of the second straight portion to form a first inclination angle. The stent assembly as described. The stent assembly according to claim 1, wherein the balloon is bent from the proximal end portion to the distal end portion in the expanded state.

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