Source: https://patents.google.com/patent/US8496699B2/en
Timestamp: 2019-04-19 17:57:16+00:00

Document:
An intravascular stent especially suited for implanting in curved arterial portions. The stent retains longitudinal flexibility after expansion. The stent is formed of intertwined meander patterns forming triangular cells. The triangular cells are adapted to provide radial support, and also to provide longitudinal flexibility after expansion. The triangular cells provide increased coverage of a vessel wall. The stent can have different portions adapted to optimize radial support or to optimize longitudinal flexibility. Loops in the stent are disposed and adapted to cooperate so that after expansion of said stent within a curved lumen, the stent is curved and cells on the outside of the curve open in length, but narrow in width whereas cells on the inside of the curve shorten in length but thicken in width to maintain a density of stent element area which much more constant than otherwise between the inside and the outside of the curve. As a result, when the stent is coated with a medicine the more constant density of stent elements results in an even dose being applied to the inside wall of the lumen, avoiding the possibility that a toxic dose be supplied at one area while a less than effective dose is applied to another area.
This application is a continuation of Ser. No. 09/864,389 filed May 25, 2001, which is a continuation-in-part of Ser. No. 09/795,794, now U.S. Pat. No. 6,709,453, filed Feb. 28, 2001, which is a continuation-in-part of Ser. No. 09/516,753 filed Mar. 1, 2000, now U.S. Pat. No. 7,141,062, and which also claims the priority of Provisional Application 60/202,723, filed May 8, 2000.
Various stents are known in the art. Typically stents are generally tubular in shape, and are expandable from a relatively small, unexpanded diameter to a larger, expanded diameter. For implantation, the stent is typically mounted on the end of a catheter, with the stent being held on the catheter at its relatively small, unexpanded diameter. By the catheter, the unexpanded stent is directed through the lumen to the intended implantation site. Once the stent is at the intended implantation site, it is expanded, typically either by an internal force, for example by inflating a balloon on the inside of the stent, or by allowing the stent to self-expand, for example by removing a sleeve from around a self-expanding stent, allowing the stent to expand outwardly. In either case, the expanded stent resists the tendency of the vessel to narrow, thereby maintaining the vessel's patency.
U.S. Pat. No. 5,733,303 to Israel et al. (“'303”), which is expressly incorporated by reference, shows a unique stent formed of a tube having a patterned shape which has first and second meander patterns having axes extending in first and second directions. The second meander patterns are intertwined with the first meander patterns to form flexible cells. Stents such as this one are very flexible in their unexpanded state such that they can be tracked easily down tortuous lumens. Upon expansion, these stents provide excellent radial support, stability, and coverage of the vessel wall. These stents are also conformable, in that they adapt to the shape of the vessel wall during implantation. It is readily apparent that, by nature, when the stent shown, for example, in FIG. 8 thereof is expanded in a curved lumen, cells on the outside of the curve open in length, but narrow in width whereas cells on the inside of the curve shorten in length but thicken in width to maintain a density of stent element area which much more constant than otherwise between the inside and the outside of the curve.
One feature of stents with a cellular mesh design such as this one, however, is that they have limited longitudinal flexibility after expansion, which may be a disadvantage in particular applications. This limited longitudinal flexibility may cause stress points at the end of the stent and along the length of the stent. Conventional mesh stents like that shown in U.S. Pat. No. 4,733,665 may simply lack longitudinal flexibility, which is illustrated by FIG. 1, a schematic diagram of a conventional stent 202 in a curved vessel 204.
To implant a stent, it maybe delivered to a desired site by a balloon catheter when the stent is in an unexpanded state. The balloon catheter is then inflated to expand the stent, affixing the stent into place. Due to the high inflation pressures of the balloon—up to 20 atm—the balloon causes the curved vessel 204 and even a longitudinally flexible stent to straighten when it is inflated. If the stent, because of the configuration of its mesh is or becomes relatively rigid after expansion, then the stent remains or tends to remain in the same or substantially the same shape after deflation of the balloon. However, the artery attempts to return to its natural curve (indicated by dashed lines) in FIG. 1 with reference to a conventional mesh stent. The mismatch between the natural curve of the artery and the straightened section of the artery with a stent may cause points of stress concentration 206 at the ends of the stent and stress along the entire stent length. The coronary vasculature can impose additional stress on stents because the coronary vasculature moves relatively significant amounts with each heartbeat. For illustration purposes, the difference between the curve of the vessel and the straightened stent has been exaggerated in FIG. 1.
U.S. Pat. No. 5,807,404 to Richter, which is expressly incorporated by reference, shows another stent which is especially suited for implantation into curved arterial portions or osteal regions. This stent can include sections adjacent the end of the stent with greater bending flexibility than the remaining axial length of the stent. While this modification at the end of the stent alleviates the stress at the end points, it does not eliminate the stress along the entire length of the stent.
The coiled zig-zag stents that are illustrated in FIGS. 1 through 6 of the Wiktor '062 and '732 patents are longitudinally flexible both in the expanded and unexpanded condition such that they can be tracked easily down tortuous lumens and such that they conform relatively closely to the compliance of the vessel after deployment. While these stents are flexible, they also have relatively unstable support after expansion. Furthermore, these stents leave large portions of the vessel wall uncovered, allowing tissue and plaque prolapse into the lumen of the vessel.
Accordingly, an object of the invention is to provide a stent that is longitudinally flexible before expansion so that it can easily be tracked down tortuous vessels and remains longitudinally flexible after expansion such that it will substantially eliminate any stress points by complying with the vessel's flexibility and assuming the natural curve of the vessel.
Other advantages of the present invention will be apparent to those skilled in the art.
In accordance with these objects, the stent of the present invention is formed to be a tube having a patterned shape which has first and second meander patterns having axes extending in first and second direction wherein the second meander patterns are intertwined with the first meander patterns.
In accordance with one embodiment of the invention, the intertwined meander patterns form cells which have three points at which the first and second meander patterns meet each other, and which in this sense could be called triangular cells. These three cornered or triangular cells are flexible about the longitudinal axis of the stent after expansion. These triangular cells provide comparable scaffolding and radial strength to that of cells formed by intertwined meander patterns which have four points at which the first and second patterns meet each other, and which in this sense could be called square cells.
In another embodiment of the invention, bands of cells are provided along the length of a stent. The bands of cells alternate between cells adapted predominantly to enhance radial support with cells that are adapted predominantly to enhance longitudinal flexibility after expansion.
In another embodiment of the invention, the first meander patterns are adapted to prevent any “flaring out” of loops of the first meander patterns during delivery of the stent.
In this and other embodiments, cells formed by the meander patterns are such that, when the expanded stent is bent while inside a lumen, the cells on the outside of the curve open in length, but narrow in width whereas the cells on the inside of the curve shorten in length but thicken in width so that the area of the cell, and the density of the struts, remains much more constant than otherwise. This results in maintaining a more constant density of stent elements in contact with the lumen, irrespective of location on the inside or outside of a curved section. In turn, when the stent is coated with a medicine, a more even dose is applied to the inside wall of the lumen, avoiding the possibility that a toxic dose be supplied at one area while a less than effective dose is applied to another area.
FIG. 1 shows a schematic diagram of a conventional rigid stent deployed in a curved lumen.
FIG. 2 shows a schematic diagram of a stent of the present invention deployed in a curved lumen.
FIG. 3 shows a pattern for a stent made in accordance with the present invention.
FIG. 4 shows an enlarged view of one cell of the pattern of FIG. 3.
FIG. 6 shows an enlarged view of one cell of the pattern of FIG. 5.
FIG. 7 shows a pattern for a stent made in accordance with the present invention.
FIG. 8 shows an enlarged view of one cell used in the pattern of FIG. 7.
FIG. 9 shows an enlarged view of another cell used in FIG. 7.
FIG. 10 shows a schematic comparison of a four cornered or “square cell” and a three cornered or “triangular” cell of the present invention.
FIG. 12 shows another pattern for a stent constructed according to the principles of the invention.
FIG. 13 shows another pattern for a stent constructed according to the principles of the invention.
FIG. 14 shows the expansion of a portion of a horizontal meander pattern built according to the principles of the invention.
FIG. 15 shows a view of the shape of single cell on the outside of a curve superimposed on the same cell on the inside of a curve.
FIG. 2 shows a schematic diagram of a longitudinally flexible stent 208 of the present invention. The stent 208 may be delivered to a curved vessel 210 by a balloon catheter, and implanted in the artery by inflating the balloon. As described before, the balloon causes the artery to straighten upon inflation of the balloon. However, upon deflation of the balloon, the stent 208 assumes the natural curve of the vessel 210 because it is and remains longitudinally flexible after expansion. This reduces any potential stress points at the ends of the stent and along the length of the stent. Furthermore, because the stent is longitudinally flexible after expansion, the stent will flex longitudinally with the vessel during the cycles caused by a heartbeat. This also reduces any cyclic stress at the ends of the stent and along the length of the stent.
FIG. 3 shows a pattern of a stent according to the present invention. This pattern may be constructed of known materials, and for example stainless steel, but it is particularly suitable to be constructed from NiTi. The pattern can be formed by etching a flat sheet of NiTi into the pattern shown. The flat sheet is formed into a stent by rolling the etched sheet into a tubular shape, and welding the edges of the sheet together to form a tubular stent. The details of this method of forming the stent, which has certain advantages, are disclosed in U.S. Pat. Nos. 5,836,964 and 5,997,973, which are hereby expressly incorporated by reference. Other methods known to those of skill in the art such as laser cutting a tube or etching a tube may also be used to construct a stent which uses the present invention. After formation into a tubular shape, a NiTi stent is heat treated, as known by those skilled in the art, to take advantage of the shape memory characteristics of NiTi and its superelasticity.
The pattern 300 is formed from a plurality of each of two orthogonal meander patterns which patterns are intertwined with each other. The term “meander pattern” is taken herein to describe a periodic pattern about a center line and “orthogonal meander patterns” are patterns whose center lines are orthogonal to each other.
A meander pattern 301 is a vertical sinusoid having a vertical center line 302. It will be recognized that this is not a perfect sinusoid, but only an approximation thereof. Thus, as used herein, the term sinusoid refers to a periodic pattern which varies positively and negatively symmetrically about an axis; it need not be an exact sine function. A meander pattern 301 has two loops 304 and 306 per period wherein loops 304 open to the right while loops 306 open to the left. Loops 304 and 306 share common members 308 and 310, where member 308 joins one loop 304 to its following loop 306 and member 308 joins one loop 306 to its following loop 304. The vertical sinusoid of meander pattern 301 has a first frequency.
A meander pattern 312 (two of which have been shaded for reference) is a horizontal pattern having a horizontal center line 314. A horizontal meander pattern 312 also has loops labeled 316, 318, 320, 322, and between the loops of a period is a section labeled 324. Looked at another way, these loops are part of a vertical sinusoid 303 which has a higher frequency than that of the meander patterns 301. Vertical sinusoids 301 alternate with vertical sinusoids 303. Vertical sinusoids 303 have a second frequency higher than the first frequency of the vertical meander patterns, i.e., sinusoids 301.
Vertical meander pattern 301 is provided in odd and even (0 and e) versions which are 1800 out of phase with each other. Thus, each left opening loop 306 of meander pattern 3010 faces a right opening loop 304 of meander pattern 301 e and a right opening loop 304 of meander pattern 3010 faces a left opening loop 306 of meander pattern 301 e.
The horizontal meander pattern 312 is also provided in odd and even forms. The straight sections 324 of the horizontal meander pattern 312 e intersect with every third common member 310 of the even vertical meander pattern 301 e. The straight sections 324 of the horizontal meander pattern 3120 also intersect with every third common member 310 of the odd vertical meander pattern 301. Viewed as vertical sinusoids 303, alternating sinusoids 303 are intermittently coupled to the meander patterns 301. For example, between points 315 and 317, where vertical pattern 303 is coupled to vertical pattern 301 e, there are two loops 306 and one loop 304 of vertical pattern 301 e and three loops 319 and two loops 321 of vertical pattern 303. This corresponds to two cycles of pattern 301 e and 3 cycles of pattern 303. Similarly, between two points of coupling between vertical pattern 3010 and vertical pattern 303 are two loops 304 and one loop 306, again making two cycles. There will be three loops 321 and two loops 319, again equal to three cycles of pattern 303.
It should be noted that the loops of the horizontal meander pattern 312, which are the loops of the vertical pattern 303 in the present invention avoids foreshortening in a self-expanding stent in a particularly effective manner. A self-expanding stent formed of a shape-memory alloy must be compressed from an expanded position to a compressed position for delivery. As shown in FIG. 7, because of the configuration of the loops 319 and 321 of the horizontal meander pattern 312, when the stent is compressed from an expanded position 602 to a compressed position 604, the length 606 of the horizontal meander pattern (width of the vertical pattern 330) naturally shrinks Consequently, when the stent expands, the loops 319 and 321 elongate and compensate for the shortening of the vertical meander patterns 301 e and 3010 as the vertical meander patterns 301 e and 3010 expand. In contrast, a horizontal meander pattern with such shapes as N-shapes will not naturally shrink longitudinally when compressed from an expanded position 608 to a compressed position 610, as illustrated in FIG. 14.
FIG. 4 is an expanded view of one flexible cell 500 of the pattern of FIG. 3. Each flexible cell 500 includes: a first member 501 having a first end 502 and a second end 503; a second member 504 having a first end 505 and a second end 506; a third member 507 having a first end 508 and a second end 509; and a fourth member 510 having a first end 511 and a second end 512. The first end 502 of the first member 501 is joined to the first end 505 of the second member 504 by a first curved member 535 to form a first loop 550, the second end 506 of the second member 504 is joined to the second end 509 of the third member 508 by a second curved member 536, and the first end 508 of the third member 507 is joined to the first end 511 of the fourth member 510 by a third curved member 537 to form a second loop 531. The first loop 550 defines a first angle 543. The second loop 531 defines a second angle 544. Each cell 500 also includes a fifth member 513 having a first end 514 and a second end 515; a sixth member 516 having a first end 517 and a second end 518; a seventh member 519 having a first end 520 and a second end 521; an eighth member 522 having a first end 523 and a second end 524; a ninth member 525 having a first end 526 and a second end 527; and a tenth member 528 having a first end 529 and a second end 530. The first end 514 of the fifth member 513 is joined to the second end 503 of the first member 501 at second junction point 542, the second end 515 of the fifth member 513 is joined to the second end 518 of the sixth member by a curved member 539 to form a third loop 532, the first end 517 of the sixth member 516 is joined to the first end 520 of the seventh member 519 by a fifth curved member 548, the second end 521 of the seventh member 519 is joined to the second end 524 of the eighth member 522 at third junction point 540 to form a fourth loop 533, the first end 523 of the eighth member 522 is joined to the first end 526 of the ninth member 525 by a sixth curved member 549, the second end 526 of the ninth member 525 is joined to the second end 530 of the tenth member 528 by a seventh curved member 541 to form a fifth loop 534, and the first end 529 of the tenth member 528 is joined to the second end 512 of the fourth member 510 at fourth junction point 538. The third loop 532 defines a third angle 545. The fourth loop 533 defines a fourth angle 546. The fifth loop 534 defines a fifth angle 547.
The first, second, third, and fourth members 501, 504, 507, 510 may have a width that is greater than the width of the fifth, sixth, seventh, eighth, ninth, and tenth members 513, 516,519,522,525,528 in that cell. The differing widths of the first, second, third, and fourth members and the fifth, sixth, seventh, eighth, ninth, and tenth members with respect to each other contribute to the overall flexibility and resistance to radial compression of the cell. The widths of the various members can be tailored for specific applications. For example, the ratio of width maybe approximately 50-70%. The fifth, sixth, seventh, eighth, ninth, and tenth members may be optimized predominantly to enable longitudinal flexibility, both before and after expansion, while the first, second, third, and fourth members may be optimized predominantly to enable sufficient resistance to radial compression to hold a vessel open. Although specific members may be optimized to predominantly enable a desired characteristic, all the portions of the cell interactively cooperate and contribute to the characteristics of the stent.
FIGS. 5 and 6 show a pattern and an expanded view of one cell of an embodiment of the present invention which is specially adapted for a stent made of stainless steel. The pattern is similar to the pattern of FIGS. 3 and 4, and the same reference numerals are used to indicate the generally corresponding parts. The stents of the embodiment of FIGS. 5 and 6 will normally be expanded by a balloon, in conventional fashion.
The embodiments of FIGS. 3 and 5 can also be viewed as being made up of high frequency and low frequency vertical sinusoidal patterns or vertical loop containing sections which are arranged generally in the circumferential direction and which are periodically interconnected. Thus, there is a first loop containing section with loops occurring at a first frequency extending along line 301 and a second loop containing section with also occurring at said first frequency extending along line 302. A third loop containing section 303 extending along line 305 has loops occurring at a second frequency that is higher than said first frequency. It is disposed between the first and second loop containing sections and alternately joined to the first and second loop containing sections. In the illustrated embodiment, the high frequency is in a ratio of 3/2 to the low frequency. As noted above, the higher frequency loop containing elements are smaller in width. The relative widths can be selected so that the high frequency elements are crimpable to the same diameter as the lower frequency elements.
Furthermore the high frequency vertical patterns of smaller width result in elements having a lower maximal strain. Specifically, the lower maximal strain is below the maximum strain without non-elastic deformation for the material of the stent. In this embodiment where the stent is made of stainless steel the lower maximal strain is below approximately 0.4%, even for a 1500 bend, as confirmed by finite element analysis. On the other hand, in a '303 type stent, for an equivalent amount of bending, exhibits a maximum strain of 8%. Thus, although the increased flexibility of the stent of the present invention means that, in addition to conforming better to the curved lumen, it will bend with each beat of the heart. The strain during heart beat happens 8,000,000 times every year and cannot be much above elastic limit without the stent breaking Since, embodiments of the present invention keep the strain below the limit means that the stent of the present invention can bend with the lumen as the heart beats, for many years without breaking.
Also in this embodiment of the invention, for example, the second loops 531 are made stronger by shortening the third and fourth members 507, 510. This helps assure that the second loops do not “flare out” during delivery of the stent through tortuous anatomy. This “flaring out” is not a concern with NiTi stents which are covered by a sheath during delivery.
When the stent is within a curved lumen when it is expanded, the stent is curved as shown in FIG. 2 The result of this curving, for a single cell 500, is shown in FIG. 15. The cells on the outside of the curve open in length, but narrow in width whereas the cells on the inside of the curve shorten in length but thicken in width. As a result, the density of the members per unit of surface area remains closer to what it is in an uncurved, expanded condition, both on the inside and outside of the curve. Similarly, as can be seen from FIG. 15, the area of the cell remains more constant than it would without compensation. This results in maintaining a more constant density of stent elements in contact with the lumen, irrespective of location on the inside or outside of a curved section. In turn, when the stent is coated with a medicine, a more even dose is applied to the inside wall of the lumen, avoiding the possibility that a toxic dose be supplied at one area while a less than effective dose is applied to another area. In some cases, the ratio between a toxic dose and an effective dose may be smaller than 10:1.
Specifically, it can be appreciated that, in cells on the outside of the curve at the connection points 542 and 538, the cell will open up increasing the length of the cell. In addition, at the junction points 535, 536, 537, 539, 540 and 542, the adjoining struts will come closer to each other, to cause the cell to become narrower in width, or in the circumferential direction, compensating for the increase in length. On the inside of the curve, the longitudinal distances must decrease. Again, it is easy to see that the compression which occurs on the inside results in the struts on either side of the junction points 542 and 538 being squeezed closed and the width of the cell decreasing. At the same time, at the junction points 535, 536, 537, 539, 540 and 542, the struts will move further apart from each other and the cell becomes more narrow in length but thicker in width again providing compensation. Thus, In both cases, the increase in one direction is compensated in the other direction to make the area more constant than it would have been without the compensation.
FIG. 7 illustrates another aspect of the present invention. The stent of FIG. 7 is also constructed from orthogonal meander patterns 301, 302. The meander patterns form a series of interlocking cells 50, 700 of two types. The first type of cell 50 is taught by U.S. Pat. No. 5,733,303. These cells are arranged so that they form alternating bands 704 of first type of cells 50 and bands 706 of the second type of cells 700.
As seen in FIG. 8 and particularly with respect to the cell labeled for ease of description, each of the '303 cells 50 has a first longitudinal apex 100 and a second longitudinal end 78. Each cell 50 also is provided with a first longitudinal end 77 and a second longitudinal apex 104 disposed at the second longitudinal end 78. Each cell 50 also includes a first member 51 having a longitudinal component having a first end 52 and a second end 53; a second member 54 having a longitudinal component having a first end 55 and a second end 56; a third member 57 having a longitudinal component having a first end 58 and a second end 59; and a fourth member 60 having a longitudinal component having a first end 61 and a second end 62. The stent also includes a first loop or curved member 63 defining a first angle 64 disposed between the first end 52 of the first member 51 and the first end 55 of the second member 54. A second loop or curved member 65 defining a second angle 66 is disposed between the second end 59 of the third member 57 and the second end 62 of the fourth member 60 and is disposed generally opposite to the first loop 63. A first flexible compensating member (or a section of a longitudinal meander pattern) 67 having curved portion and two legs with a first end 68 and a second end 69 is disposed between the first member 51 and the third member 57 with the first end 68 of the first flexible compensating member 67 joined to and communicating with the second end 53 of the first member 51 and the second end 69 of the first flexible compensating member 67 joined to and communicating with the first end 58 of the third member 57. The first end 68 and the second end 69 are disposed a variable longitudinal distance 70 from each other. A second flexible compensating member (or, a section of a longitudinal meander pattern) 71 having a first end 72 and a second end 73 is disposed between the second member 54 and the fourth member 60. The first end 72 of the second flexible compensating member 71 is joined to and communicates with the second end 56 of the second member 54 and the second end 73 of the second flexible compensating member 71 is joined to and communicates with the first end 61 of the fourth member 60. The first end 72 and the second end 73 are disposed a variable longitudinal distance 74 from each other. In this embodiment, the first and second flexible compensating members, and particularly the curved portion thereof, 67 and 71 are arcuate.
When curved stent is expanded while inside a lumen, also in the case of the cells 50, cells on the outside of the curve open in length, but narrow in width whereas the cells on the inside of the curve shorten in length but thicken in width to provide a density of the members per unit of surface area that remains more constant between the inside and outside of the curve.
Specifically, it can be appreciated that, in cells on the outside of the curve the flexible connecting members 67 and 71 will open up increasing the distances 70 and 74. In addition, the members 57 and 60 will come closer to each other, as will members 51 and 54. This will further lengthen the cell. But at the same time it will become narrower in width, or in the circumferential direction to compensate for the opening up of the flexible connector members 67 and 71. On the inside of the curve, the longitudinal distances must decrease. Again, if is easy to see that the compression which occurs on the inside results in the loops 67 and 71 being squeezed closed and the distances 70 and 74 decreasing. At the same time, the members 57 and 60 and members 51 and 54 will move further apart from each other and the longitudinal components of members 57, 60, 51 and 54 will decrease. Thus, the cell becomes narrower in length but thicker in width. Thus, in both cases, the increase in one direction is compensated in the other direction to make the area more constant than it would have been without the compensation.
The second type of cell 700 is illustrated in FIG. 9 and the same reference numerals are used to indicate generally corresponding areas of the cell. The apices 100, 104 of the second type of cell 700 are offset circumferentially. Also, each flexible compensating member 67, 71 includes: a first portion or leg 79 with a first end 80 and a second end 81; a second portion or leg 82 with a first end 83 and a second end 84; and a third portion or leg 85 with the first end 86 and a second end 87, with the second end 81 and the second end 84 being joined by a curved member and the first end 83 and the first end 86 being joined by a curved member. The first end of a flexible compensating member 67, 71 is the same as the first end 80 of the first portion 79, and the second end of a flexible compensating member 67, 71 is the same as the second end 87 of the third portion 85. A first area of inflection 88 is disposed between the second end 81 of the first portion 79 and the second end 84 of the second portion 82 where the curved portion joining them lies. A second area of inflection 89 is disposed between the first end 83 of the second portion 82 and the first end 86 of the third portion 85 where the curved portion joining them lies.
On the right side of FIG. 10, a pair of vertical meander patterns 822, 824 are joined together compensating members 828, 830, 832, 834 (which are sections of a longitudinal meander) to form a plurality of square cells 804. By square cell, it is meant that there are four sections, each having loop portions, and four associated points of their joining, forming each cell. For example, the shaded cell 802 is formed from .four sections 832, 836, 830, 838, with four associated points of their joining 840, 842, 844, 846.
Both the square cell and the triangular cell have two kinds of sections with loops. The first kind of loop containing section is formed from a vertical meander pattern and is optimized predominantly to enable radial support. The second kind of loop containing section is optimized predominantly to enable flexibility along the longitudinal axis of the stent. Although each loop containing section is optimized predominantly to enable a desired characteristic of the stent, the sections are interconnected and cooperate to define the characteristics of the stent. Therefore, the first kind of loop containing section contributes to the longitudinal flexibility of the stent, and the second kind of loop containing section contributes to the radial support of the stent.
In the square cell 802, it can be seen that the second kind of loop containing sections 830, 832 each have one inflection point 848, 850. In the triangular cell, the loop containing sections 810, 812 each have two inflection point areas 852, 854, 856, 858. The higher number of inflection points allows more freedom to deform after expansion of the stent and distributes the deformation over a longer section, thus, reducing the maximal strain along these loop containing sections.
If the first meander patterns 806, 822, 824, 826 of both types of cells are constructed identically and spaced apart by the same amount, the area of a triangular cell 804 is the same as a square cell 802. This can be more readily understood with reference to a band of cells around the circumference of a stent. Each band will encompass the same area, and each band will have the same number of cells. Accordingly, the area of each cell in one band formed of square cells will be the same as the area of each cell in another band formed of triangular cells.
In the particular embodiments described above, the stent is substantially uniform over its entire length. However, other applications where portions of the stent are adapted to provide different characteristics are also possible. For example, as shown in FIG. 11, a band of cells 850 may be designed to provide different flexibility characteristics or different radial compression characteristics than the remaining bands of cells by altering the widths and lengths of the members making up that band. Or, the stent may be adapted to provide increased access to a side branch lumen by providing at least one cell 852 which is larger in size then the remaining cells, or by providing an entire band of cells 854 which are larger in size than the other bands of cells. Or, the stent may be designed to expand to different diameters along the length of the stent. The stent may also be treated after formation of the stent by coating the stent with a medicine, plating the stent with a protective material, plating the stent with a radiopaque material, or covering the stent with a material.
FIGS. 12 and 13 show alternative patterns for a stent constructed according to the principles of the present invention. The stent shown in FIG. 12 has two bands of cells 856 located at each of the proximal end 860 and distal and 862. The cells that form the bands of cells 856 located at the ends of the stent are '303 type cells. The remaining cells in the stent are the same as described with respect to the cells 500 depicted in FIG. 6. The stent shown in FIG. 13 has alternating bands of cells 864, 866, 868. The first type of band of cells 864 is composed of '303 type cells. The second and third types of bands of cells 866, 868 are formed of the cells described with respect to the cells 500 depicted in FIG. 4. Of course, any various combination of cells may be used in the present invention.
wherein the first circumferential bands, second circumferential bands and flexible connectors comprise struts having a width in the circumferential direction, wherein the struts of the first and second circumferential bands are wider than the width of the struts of the flexible connectors.
e. wherein the loops of the first, second, and third loop containing sections comprise struts having a width in the circumferential direction, wherein the struts of the first and second loop containing sections are wider than the width of the struts of the third loop containing section.
wherein the longitudinal axis of each of said first, second and third legs lies generally aligned with the longitudinal axis of the stent.
4. A stent according to claim 3 wherein a loop connects said first leg to said second leg of a flexible compensating member.
5. A stent according to claim 3 wherein a loop connects said second leg to said third leg of a flexible compensating member.
6. A stent according to claim 3 wherein each said flexible compensating member connects a loop of a first circumferential band with a circumferentially offset loop of a second circumferential band.
7. A stent according to claim 3 wherein the loops of said first circumferential bands are out-of-phase with the loops of said second circumferential bands.
f. a second flexible compensating member having a first end, a second end and struts forming the shape of a Z, wherein the longitudinal axis of each of said struts lies generally aligned with the longitudinal axis of the stent, wherein said first end connects with said first end of said second member, and said second end connects with said second end of said third member.
BSC Cancellation Proceeding against DE Patent No. 20108764 as filed on Jan. 10, 2003, 336 pages.
BSC Cancellation Proceeding against DE Patent No. 20108765 as filed on Jan. 10, 2003, 323 pages.
European Search Report EP Application No. 04806450.5-1257 (published as EP 1 703 856) dated Aug. 16, 2007, 3 pages.
European Search Report for EP 01125341.6 (now abandoned) dated Jan. 14, 2005, 7 pages.
European Search Report from corresponding EP Application No. 08001226.3-1257 (publication as 1 908 437) dated Feb. 4, 2010, 5 pages.
IDS Letter dated Jul. 9, 2003 for US Appl. No. 09/864,389, 2 pages.
New Zealand Examination Report dated May 24, 2001 for Patent Application No. NZ 510244, 6 pages.
Office Actions and Response of related U.S. Appl. No. 11/395,751: Notice of Allowance and Examiner Initiated Interview Summary dated Jul. 27, 2012; and, Amendment and Response to Non-Final OA dated Apr. 24, 2012.
Office Actions and Response of related U.S. Appl. No. 12/842, 292: Amendment and Response to Non-Final Rejection dated Jun. 1, 2012.
Office actions and response of related U.S. Appl. No. 12/842,292: Non-Final Rejection dated Mar. 2, 2012.
Office Actions and responses of related U.S. Appl. No. 11/395,751: Non-Final Rejection dated Jan. 24, 2012.
Office Actions and responses of related U.S. Appl. No. 12/042,470: Notice of Allowance dated Feb. 8, 2012.
Office Actions and Responses to Office Actins of related U.S. Appl. No. 10/040,789 now abandoned: Notice of Abandonment dated Jun. 6, 2005; Response to Non-Complaint Amendment dated Apr. 21, 2005; Notice of Non-Complaint Amendment dated Mar. 21, 2005; Amendment and Response to Non-Final Rejection dated Feb. 24, 2005; Non-Final Rejection dated Aug. 25, 2004; Preliminary Amendment dated Jan. 16, 2003.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 09/516,753, issued as US Patent No. 7,141,062: Notice of Allowance mailed Jul. 28, 2006; Amendment and Response to Final Rejection dated Jun. 8, 2006; Final Rejection dated Dec. 8, 2005; Amendment and Response to Non-Final Rejection dated Aug. 15, 2005; Non-Final Rejection dated Mar. 15, 2005; Response to Election Requirement dated Nov. 2, 2004; Election Requirement dated Aug. 11, 2004; Amendment and Response to Final Rejection dated May 13, 2004; Final Rejection dated Feb. 6, 2004; Amendment and Response to Non-Final Rejection dated Nov. 13, 2003; Non-Final Rejection dated Aug. 13, 2003; Amendment and Response to Final Rejection dated Jun. 2, 2003; Final Rejection dated Dec. 3, 2002; Amendment and Response to Non-Final Rejection dated Jul. 26, 2002; Non-Final Rejection dated Jan. 30, 2002.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 09/795,794, issued as US Patent No. 6,709,453: Notice of Allowance dated Sep. 24, 2003; Supplemental Response dated Sep. 22, 2003; Supplemental Response dated Sep. 17, 2003; Amendment and Response to Final Office Rejection dated Sep. 11, 2003; Non-Final Rejection dated Jul. 15, 2003; Amendment and Response to Final Rejection dated May 1, 2003; Final Rejection dated Jan. 30, 2003; Supplemental Amendment dated Aug. 5, 2002; Response to Non-Final Rejection dated Jun. 19, 2002; Non-Final Rejection dated Dec. 20, 2001.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 09/864,160 issued as US Patent No. 6,723,119: Notice of Allowance dated Sep. 26, 2003; Supplemental Response after Final Rejection dated Sep. 17, 2003; Response after Final Rejection dated Sep. 11, 2003; Notice of Appeal dated Jun. 3, 2002; Final Rejection dated Dec. 3, 2002; Supplemental Response dated Aug. 5, 2002; Amendment and Response to Non-Final Rejection dated Jun. 26, 2002; Non-Final Rejectin Dated Jan. 29, 2002.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 10/236,144 issued as US Patent No. 7,621,947: Notice of Allowance dated Jul. 13, 2009; Terminal Disclaimer filed, dated May, 8, 2009; Amendment and Response to Non-Final Office Action with Extension of Time Dated Feb. 2, 2009; Non-Final Rejection dated Oct. 2, 2008; Request for Continued Examination (RCE); Amendments and Response to the Final Rejection dated Aug. 22, 2008; Final Rejection dated May 23, 2008; Amendment and Response to Final Rejection with Extension of Time dated Jan. 9, 2008; Non-Final Rejection dated Sep. 21, 2007; Amendment and Response to Final Rejection, Request for Continued Examination (RCE), Extension of Time, and Terminal Disclaimer dated Jun. 26, 2007; Final Rejection dated Feb. 26, 2007; Amendment and Response to Non-Final Rejection dated Aug. 7, 2006; Non-Final Rejection dated Feb. 8, 2006; Response to Election Requirement dated Nov. 17, 2005; Election Requirement dated Sep. 21, 2005.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 10/619,837, issued as US Patent No. 7,722,658: Notice of Allowance dated Oct. 13, 2009; Request for Continued Examination (RCE); Amendment and Response to Final Rejection dated Jul. 29, 2009; Final Rejection dated Apr. 4, 2009; Amendment and Response to Non-Final Rejection with Extension of Time dated Dec. 16, 2008; Non-Final Rejection dated Jul. 23, 2008; Amendment and Response to Non-Final Rejection and Terminal Disclaimer dated Feb. 4, 2008; Non-Final Rejection dated Oct. 4, 2007; Respose to Restriction/Election Requirement dated Feb. 5, 2007; Requirement for Restriction/Election dated Jan. 4, 2007.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 10/660,883 now abandoned: Notice of Abandonment dated Apr. 28, 2009; Advisory Action dated Jan. 30, 2009; Amendment and Response to Final Rejection with Extension of Time dated Jan. 7, 2009; Final Rejection dated Aug. 7, 2008; Response to Election/Restriction Requirement dated May 28, 2008; Requirememt for Restriction/Election dated Apr. 28, 2008; Requirement for Restriction/Election dated Apr. 28. 2008; Amendment and Response to Non-Final Rejection dated Jan. 25, 2008; Non-Final Rejection dated Oct. 25, 2007.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 10/757,805, issued as US Patent No. 7,758,627: Amendment after Notice of Allowance dated Mar. 16, 2010; Notice of Allowance dated Dec. 17, 2009; Amendment and Response to Final Rejection with Request for Continued Examination (RCE) dated Jun. 29, 2009; Final Rejection dated Apr. 16, 2009; Amendment and Response to Non-Final Rejection with Extension of Time dated Jan. 14, 2009; Amendment and Response to Non-Final Rejection with Extension of Time dated Jan. 14, 2009; Non-Final Rejection dated Aug. 14, 2008; Amendment and Response to Restriction/Election Requirement dated May 7, 2008; Requirement for Restriction/Election dated Apr. 7, 2008.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 11/395,751: Amendment and Response to Final Rejection with Request for Continued Examination dated Oct. 13, 2010; Final Rejection dated Jul. 14, 2010; Amendment and Response to Supplemental Non-Final Rejection dated Feb. 22, 2010; Supplemental Non-Final Rejection dated Nov. 20, 2009; Non-Final Rejection dated Oct. 20, 2009; Pre-Appeal Conference Decision dated Aug. 5, 2009; Notice of Appeal with Extension of Time and Pre-Brief Conference Request dated May 14, 2009; Final Rejection dated Dec. 15, 2008; Amendment and Response to Non-Final Rejection dated Aug. 20, 2008; Non-Final Rejection dated Apr. 23, 2008; Response to Election/Restriction Requirement dated Dec. 10, 2007; Requirement for Restriction/Election dated Nov. 8. 2007; Amendment and Response to Non-Final Rejectin with Terminal Disclaimer dated Jul. 11, 2007; Non-Final Rejection dated Apr. 11, 2007.
Office Actions and Responses to Office Actions of related U.S. Appl. No. 12/042,470: Amendment and Response to Final Rejection with Request for Continued Extension of Time dated Feb. 1, 2011; Final Rejection dated Nov. 1, 2010; Response to Non-Final Rejection dated Aug. 10, 2010; Non-Final Rejection dated May 10, 2010; Supplemental Amendment and Response to Non-Final Rejection dated Apr. 26, 2010; Correspondence dated Mar. 1, 2010 confirming that the Aug. 19, 2009 Restriction Requirement was sent in error by the Examiner; Non-Final Rejection/ Requirement for Restriction/Election dated Aug. 19, 2009; Response to Election/Restriction Requirement dated Apr. 20, 2009; Requirement for Restriction/Election dated Mar. 20, 2009; Amendment and Response to Non-Final Rejection dated Dec. 17, 2008; Supplemental Amendment and Response to Non-Final Rejection dated Dec. 17, 2008; Non-Final Rejection dated Sep. 17, 2008.
Partial European Search Report for EP 01125341.6-1257 (now abandoned) dated Oct. 25, 2004, 6 pages.
Patent Act 1977: Search Report under Section 17 for GB 04 02 849.4 dated Apr. 8, 2004, 1 page.
Singapore Examination Report, Application No. 200100915-8 dated Nov. 28, 2002, 4 pages.
Supplemental European Search Report for EP Application No. 02733009.1-2310 (now abandoned) dated Aug. 1, 2006, 3 pages.
Supplemental European Search Report for EP Application No. 02767765.7-1257 (now abandoned) dated Mar. 16, 2005, 3 pages.
Translated German Office Action, Application No. 101 09 508.2-43, 1 page, dated Feb. 18, 2003.

References: Application No. 04806450
 Application No. 08001226
 Application No. 200100915
 Application No. 02733009
 Application No. 02767765
 Application No. 101