Stent device with reduced shortening and recoil and method of making same

Abstract

To provide a suitable stent device having reduced foreshortening and recoil and a suitable method of making the device.SOLUTION: A stent device 210 includes generally cylindrical rings 212 aligned along a longitudinal axis, and interconnected by interconnecting members 216. Each interconnecting member includes first and second coupling ends 218 and an elongate portion 220 therebetween. The first coupling end, the elongate portion, and the second coupling end combine in either a first orientation or a second orientation, which are substantially mirror images. For each interconnecting member, the first coupling end can intersect with a midpoint of a transition region 228 of a substantially repeating curved segment on one of the rings, and the second coupling end can intersect with a midpoint of a curved segment of a different and immediately adjacent ring. The interconnecting members can be arranged in rows extending longitudinally along the device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to and the benefit of co-pending U.S. application Ser. No. 13 / 834,250, filed March 15, 2013, the entire disclosure of which is incorporated herein by reference, for all subject matter common to both applications.

[0002] The present invention relates to expandable intraluminal devices for use within body passageways or ducts. More particularly, the present invention relates to stent devices and methods for their manufacture that exhibit substantially improved characteristics over known devices in the form of reduced foreshortening and recoil. [Background technology]

[0003] A common method of treating stenosed blood vessels or other blocked passageways is with an expandable prosthesis or stent. The stent is delivered to the target site, expanded, and fixed in place. The deployed and fixed stent creates an enlarged lumen space and also provides further strengthening of the vessel wall, maintaining a clear passageway for blood to pass through. Stents can be covered or uncovered. Some covered stents provide a series of interconnected metal rings encapsulated by a layer of biocompatible material. In uncovered stents (called "bare metal stents"), the series of interconnected metal rings are directly exposed to the blood vessel and do not include any type of covering.

[0004] Covered stents are often preferable to bare metal stents because, in addition to other advantages, they provide more uniform coverage (e.g., gaps between stent struts are not exposed to the target site wall) and improved luminal patency. However, covered stents suffer from several operational drawbacks, including undesirable degrees of foreshortening and recoil. In contrast, many bare metal stents exhibit little or no foreshortening and minimal recoil when deployed. Meanwhile, identical stents often foreshorten by 25% or more when deployed with a cover. However, in some cases, covered stents are superior to bare metal stents in terms of freedom from restenosis within a certain defined time period (e.g., within the first 18 months after stent implantation).

[0005] For example, FIG. 1 illustrates an example of a known stent design: a conventional covered stent 110 (the covering is not shown for clarity). The stent 110 is shown in a flattened, non-continuous state for illustrative purposes. The stent 110 is actually generally cylindrical and includes a series of rings 112 that are continuous at their ends (i.e., connected above and below). The rings 112 are generally cylindrical and aligned in series. Each ring 112 generally consists of a plurality of repeating peaks and valleys 114a, 114b. In the exemplary stent 110 of FIG. 1, each particular ring 112 is a mirror image of any adjacent ring 112 in series. Thus, for any two adjacent rings 112, the peaks 114a of one ring 112 are circumferentially aligned with the valleys 114b of the other ring 112, and vice versa. Each repetition of the peaks 114a and valleys 114b forms a repeating curved section 122. The rings 112 are secured together by a plurality of interconnecting members 116. Each interconnecting member 116 includes two bends 118 and an extension 120 therebetween.

[0006] In general, each interconnection member 116 can occupy any one of a number of different configurations. In an "up-up" or "down-down" configuration, the bent portions 118 of a single interconnection member 116 extend on the same side of the elongated portion 120 (e.g., the top or bottom, respectively). In other words, in an "up-up" or "down-down" configuration, the bent portions 118 of a single interconnection member 116 extend in the same circumferential direction (e.g., clockwise or counterclockwise). On the other hand, in an "up-down" or "down-up" configuration, the two bent portions 118 of a single interconnection member 116 extend on different sides of the elongated portion 120 (e.g., the top and bottom or bottom and top, respectively).

[0007] In the embodiment of FIG. 1 , each of the interconnecting members 116 is in either a “down-up” configuration or an “up-down” configuration, which is a conventional and common design for many known stents. Furthermore, in the exemplary stent 110 of FIG. 1 , there are half as many interconnecting members 116 between any two adjacent rings 112 as there are repeating curved sections 122 in any single ring 112, which is also a common design feature for known stents. The stent 110 includes a cover (not shown for clarity). The cover can be constructed from a biocompatible material such as expanded polytetrafluoroethylene (ePFTE).

[0008] Conventional stents, especially when covered, are often associated with operational defects, including excessive foreshortening and recoil. Foreshortening is the property of a stent decreasing in length during expansion. Recoil is the property of a stent contracting from an expanded diameter to a partially expanded or unexpanded diameter. Excessive foreshortening can be particularly problematic because it compromises the stent's ability to ensure accurate placement and treatment of stenotic vessels and increases the risk of damage to the surrounding intima during expansion. Furthermore, excessive recoil is believed to be associated with other risks, such as reduced reinforcement, which can lead to further obstruction and blockage of the affected passageway. It is generally believed that the reduced efficiency of covered stents (e.g., caused by substantial amounts of foreshortening and substantial amounts of recoil) is linked to a higher risk of restenosis in clinical settings. Therefore, to optimize a stent for safe and efficient use, these negative characteristics should be eliminated or at least kept to an acceptably low level. Summary of the Invention [Means for solving the problem]

[0009] There is a need for a stent device that is coverable and has low foreshortening and recoil characteristics. The present invention is directed to a solution to address this need, as well as other desirable characteristics that will be recognized by those skilled in the art upon reading this specification.

[0010] According to an exemplary embodiment of the present invention, a stent device is provided. The stent device includes a plurality of generally cylindrical rings, each formed from a plurality of substantially repeating curved segments. Each of the plurality of curved segments includes a substantial peak, a substantial valley, and a transition region connecting the substantial peak and the substantial valley. Each curved segment has a midpoint substantially halfway between the substantial peak and the substantial valley on the transition region. The plurality of rings are arranged in series along the longitudinal axis such that the substantial peak and the substantial valley of each curved segment of each ring in the series are substantially mirror images of the substantial peak and the substantial valley of the corresponding curved segment in the immediately adjacent ring. The stent device includes a plurality of interconnecting members, each of which includes a first connecting end and a second connecting end opposite the first connecting end. An extension portion extends between the first connecting end and the second connecting end. The first link end, extension portion, and second link end intersect in a first orientation or a second orientation that is a substantial mirror image of the first orientation. The first link end intersects a midpoint of a transition region of a curved section of a ring of the plurality of rings, and the second link end intersects a midpoint of a curved section of a different and immediately adjacent ring of the plurality of rings. The plurality of interconnecting members are arranged in rows extending longitudinally along the device. Along each row, the interconnecting members alternate between the first orientation and the second orientation at each successive occurrence. The stent device further includes a cover disposed over the plurality of cylindrical rings and the plurality of interconnecting members.

[0011] According to an exemplary embodiment of the present invention, a stent device is provided. The stent device includes a plurality of generally cylindrical rings, each formed by a plurality of substantially repeating curved segments. Each of the plurality of curved segments includes peaks, valleys, and transition regions extending between the peaks and valleys. Each curved segment has a midpoint substantially halfway between the peaks and valleys on the transition region. The plurality of rings are arranged in series along the longitudinal axis such that the peaks and valleys of each curved segment of each ring in the series are substantially mirror images of the peaks and valleys of the corresponding curved segment in the immediately adjacent ring. A plurality of interconnecting members are included in the stent device, each of the plurality of interconnecting members including a first connecting end and a second connecting end opposite the first connecting end. The interconnecting member connects one of the plurality of rings to the ring adjacent to the one of the plurality of rings. An extension portion extends between the first connecting end and the second connecting end. The first link end, extension portion, and second link end intersect in a first orientation or a second orientation that is a substantial mirror image of the first orientation. The first link end intersects a midpoint of a transition region of a curved section of a ring of the plurality of rings, and the second link end intersects a midpoint of a curved section of a different and immediately adjacent ring of the plurality of rings. The plurality of interconnecting members are arranged in rows extending longitudinally along the device. Along each row, the interconnecting members alternate between the first orientation and the second orientation at each successive occurrence. The stent device further includes a cover disposed over the plurality of cylindrical rings and the plurality of interconnecting members.

[0012] According to an aspect of the invention, each of the first and second link ends of each of the plurality of interconnecting members can include a bend. The number of interconnecting members between any two adjacent rings of the plurality of rings can be equal to the number of repeating curved segments in each of the plurality of rings. According to an aspect of the invention, the stent has three adjacent sets of rings, the first set of rings including a central ring and a second ring, and the second set of rings including a central ring and a third ring. The number of interconnecting members between a first set of rings of the plurality of rings is equal to the number of repeating curved segments in a second set of rings of the plurality of rings.

[0013] According to aspects of the present invention, the first and second link ends of each of the plurality of interconnecting members can be azimuthally aligned. The first and second link ends of each of the plurality of interconnecting members can be circumferentially aligned. Each of the plurality of rings can be independently radially expandable. The independent expandability of each of the plurality of rings can occur within a range of diameters between an operational deployed diameter and an initial diameter, the initial diameter being smaller than the operational deployed diameter. The plurality of repeating curved segments can form a generally sinusoidal and / or "S"-shaped pattern. The peak-valley amplitude can be substantially equal for each of the plurality of rings. Similarly, the peak-valley amplitude can be within a tolerance range of the average amplitude measured for each of the plurality of rings. The tolerance range can be 20% of the average amplitude, 15% of the average amplitude, 10% of the average amplitude, or 5% of the average amplitude. Each of the plurality of curved segments can have a substantially uniform width. All of the plurality of curved segments have a substantially uniform width. One or more of the plurality of interconnecting members can have a substantially non-uniform width. The plurality of curved sections can have a width within a tolerance range of the average thickness of the plurality of curved sections. The tolerance range may be 20% of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness. Further, all of the plurality of curved sections can have a width within a tolerance range of the average thickness of all of the plurality of curved sections, the tolerance range being 20% ​​of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness.

[0014] According to aspects of the present invention, the cover can include one or more cover materials, one or more coatings, or both. The cover can substantially entirely cover the plurality of rings. The cover can include expanded polytetrafluoroethylene (ePTFE). The plurality of rings can be composed of one or more of a non-biodegradable alloy, stainless steel, or cobalt chromium. When a stent device having a cover is expanded to an operable deployed diameter, the stent device can exhibit a foreshortening of about 6% or less, about 3% or less, about 2% or less, about 1% or less, or about 0% or less. The stent device having a cover can exhibit about 0% foreshortening when expanded to an operable deployed diameter. The stent device having a cover can exhibit a recoil of about 6.6% or less when the stent device having a cover has an initial diameter of 1.6 mm and an expanded diameter of 5 mm. The stent device having a cover can exhibit a recoil of about 7% or less when the covered stent has an initial diameter of 1.7 mm and an expanded diameter of 6 mm. The covered stent device can exhibit a recoil of about 6.7% or less when the covered stent device has an initial diameter of 1.8 mm and an expanded diameter of about 7 mm.

[0015] According to an exemplary embodiment of the present invention, a stent device is provided. The stent device includes a stent including a plurality of radially expandable rings arranged in series along a common longitudinal axis and connected by a plurality of interconnecting members. Each of the plurality of radially expandable rings includes a plurality of substantially repeating curved sections. The number of interconnecting members between adjacent expandable rings is equal to the number of valleys between each of the adjacent expandable rings. The number of interconnecting members between adjacent expandable rings may also be equal to the number of peaks between each of the adjacent expandable rings. Each of the interconnecting members has an extension portion, a first linking end, and a second linking end. The first linking end, the extension portion, and the second linking end are combined in a first orientation or a second orientation, the second orientation being a substantial mirror image of the first orientation. The interconnecting members of a first set of two adjacent expandable rings are in the first orientation, and the interconnecting members of a second set of two adjacent expandable rings are in the second orientation. Only one of the second set of expandable rings is shared with the first set of expandable rings. The interconnecting members are arranged in series along the length of the stent, forming a sinusoidal waveform with inflection points where the interconnecting members connect to the expandable rings. A cover formed from expanded polytetrafluoroethylene and including an inner layer and an outer layer can encapsulate the stent. The stent device and cover can exhibit foreshortening of about 6% or less when expanded to an operable deployed diameter.

[0016] According to aspects of the present invention, a covered stent device can exhibit about 3% or less foreshortening when expanded to an operational deployed diameter. A covered stent device can exhibit about 2% or less foreshortening when expanded to an operational deployed diameter. The operational deployed diameter can be about 4 mm to about 8 mm, more preferably about 5 mm to about 7 mm. A covered stent device can exhibit about 1% or less foreshortening when expanded to an operational deployed diameter. A covered stent device can exhibit about 0% or less foreshortening when expanded to an operational deployed diameter.

[0017] According to an exemplary embodiment of the present invention, each of the plurality of curved sections may have only one peak and only one valley, and the peaks and valleys of each curved section may be the only peaks and valleys within the plurality of curved sections.

[0018] In an exemplary embodiment of the present invention, a method for manufacturing a stent device includes providing a plurality of generally cylindrical rings, each formed from a plurality of substantially repeating curved segments. Each of the plurality of curved segments includes one substantial peak, one substantial valley, and a transition region connecting the one substantial peak and the one substantial valley. Each curved segment has a midpoint substantially halfway between the one substantial peak and the one substantial valley on the transition region. The plurality of rings are arranged in series along the longitudinal axis such that the one substantial peak and one substantial valley of each curved segment of each ring in the series is a substantial mirror image of the one substantial peak and one substantial valley of the corresponding curved segment in the immediately adjacent ring. A plurality of interconnecting members are provided, each of the plurality of interconnecting members including a first connecting end, a second connecting end opposite the first connecting end, and an extension portion extending between the first connecting end and the second connecting end. The first connecting end, the extension, and the second connecting end are interdigitated in a first orientation or a second orientation that is a substantial mirror image of the first orientation. A cover can be provided over the plurality of cylindrical rings and the plurality of interconnecting members. The first connecting end intersects a midpoint of a transition region of a curved section of one of the plurality of rings, and the second connecting end intersects a midpoint of a curved section of a different and immediately adjacent ring of the plurality of rings. The plurality of interconnecting members are arranged in rows extending longitudinally along the device. Along each row, the interconnecting members alternate between the first orientation and the second orientation at successive occurrences, respectively.

[0019] According to an exemplary embodiment of the present invention, a method for manufacturing a stent device includes providing a plurality of generally cylindrical rings, each formed from a plurality of repeating curved segments. Each of the plurality of curved segments includes peaks, valleys, and transition regions extending between the peaks and valleys. Each curved segment has a midpoint on the transition region substantially midway between the peaks and valleys. The plurality of rings are arranged in series along the longitudinal axis such that the peaks and valleys of each curved segment of each ring in the series are substantially mirror images of the peaks and valleys of the corresponding curved segment in the immediately adjacent ring. A plurality of interconnecting members are provided, each of the plurality of interconnecting members including a first linking end, a second linking end opposite the first linking end, and an extension portion extending between the first linking end and the second linking end. The first linking end, the extension portion, and the second linking end are aligned in a first orientation or a second orientation that is substantially a mirror image of the first orientation. A cover can be applied over the plurality of cylindrical rings and the plurality of interconnecting members. The first link end intersects a midpoint of a transition region of the curved section of one of the plurality of rings, and the second link end intersects a midpoint of a curved section of a different and immediately adjacent ring of the plurality of rings. The plurality of interconnect members are arranged in rows extending longitudinally along the device. Along each row, the interconnect members alternate between a first orientation and a second orientation at each successive occurrence.

[0020] According to further aspects of the present invention, the first and second link ends of each of the plurality of interconnecting members may each include a bend. The number of interconnecting members between any two adjacent rings of the plurality of rings may be equal to the number of repeating curved sections in each of the plurality of rings. The first and second link ends of each of the plurality of interconnecting members may be aligned azimuthally. The first and second link ends of each of the plurality of interconnecting members may be aligned circumferentially. Each of the plurality of rings may independently expand radially. The plurality of repeating curved sections may form a generally sinusoidal and / or somewhat "S"-shaped pattern. The peak-valley amplitude may be substantially equal for each of the plurality of rings. Each of the plurality of curved sections may have a substantially uniform width. All of the plurality of curved sections may have substantially the same substantially uniform width. One or more of the plurality of interconnecting members may have a substantially non-uniform width.

[0021] According to a further aspect of the present invention, the cover can substantially cover the entire length of the plurality of rings. The cover can include expanded polytetrafluoroethylene (ePTFE). The cover can include one or more cover materials or one or more coatings. The plurality of rings can be composed of one or more of a non-biodegradable alloy, stainless steel, or cobalt chromium. The stent device with the cover can be expanded to an operational diameter, such that the stent device exhibits foreshortening of about 6% or less, about 3% or less, about 2% or less, about 1% or less, or about 0% or less. The stent device with the cover can exhibit about 0% foreshortening when expanded to an operational diameter.

[0022] According to an exemplary embodiment of the present invention, a stent device is provided. The stent device includes a stent including a plurality of radially expandable rings arranged in series along a common longitudinal axis and connected by a plurality of interconnecting members. Each of the plurality of radially expandable rings includes a plurality of substantially repeating curved sections. The stent device can include a cover formed of expanded polytetrafluoroethylene. The cover includes an inner layer and an outer layer, and the cover encapsulates the stent. The stent device with the cover exhibits a shortened regime indicated by the shortened curve shown in FIG. 6 or below the shortened curve shown in FIG. 6.

[0023] According to aspects of the present invention, the stent can have a length of about 24 mm or about 16 mm, and the stent device having the cover can exhibit shortening as shown by one of the shortening curves shown in FIG. 6.

[0024] According to an aspect of the present invention, a stent device is provided that includes a plurality of radially expandable rings connected together by a plurality of interconnecting members arranged as shown in Figure 3A.

[0025] According to an aspect of the present invention, a method of installing a stent device is provided. The method includes the steps of delivering any of the stent devices described above to a site and expanding the stent device from a first diameter to a second diameter, the second diameter being greater than the first diameter. The site may be a lumen, such as a vessel. The vessel may be a blood vessel of a living or non-living mammal. The expanding step may be accomplished using an inflatable balloon membrane.

[0026] According to aspects of the inventive method, the second diameter can be an operational deployed diameter and the first diameter can be less than half the size of the operational deployed diameter. The operational deployed diameter can be between about 4 mm and about 8 mm. Additionally, the operational deployed diameter can be between about 5 mm and about 7 mm.

[0027] According to aspects of the inventive method, the stent device exhibits a foreshortening of about 6% or less. More preferably, the stent device exhibits a foreshortening of about 3% or less when expanded to the second diameter. The stent device may further exhibit a foreshortening of about 2% or less when expanded to the second diameter. The stent device may further exhibit a foreshortening of about 1% or less when expanded to the second diameter. Still further, the stent device may exhibit a foreshortening of about 0% or less when expanded to the second diameter. The present invention provides, for example, the following. (Item 1) 1. A stent device comprising: a plurality of generally cylindrical rings each formed by a plurality of repeating curved segments, each of the plurality of curved segments comprising a peak, a valley, and a transition region extending between the peak and the valley, each curved segment having a midpoint substantially halfway between the peak and the valley on the transition region, the plurality of rings being arranged in series along a longitudinal axis such that the peaks and valleys of each curved segment of each ring in the series are substantially mirror images of the peaks and valleys of a corresponding curved segment in an immediately adjacent ring; a plurality of interconnecting members connecting one of the plurality of rings to a ring adjacent to the one of the plurality of rings, each of the plurality of interconnecting members comprising: a first connecting end; a second connecting end opposite the first connecting end; an extension portion extending between the first connecting end and the second connecting end, wherein the first connecting end, the extension portion, and the second connecting end are combined in a first orientation or a second orientation, the second orientation being a substantial mirror image of the first orientation; a plurality of interconnect members comprising: Equipped with the first link end intersects the midpoint of the transition region of the curved section of the one ring of the plurality of rings, and the second link end intersects the midpoint of the curved section of the immediately adjacent ring of the plurality of rings; the plurality of interconnect members are arranged in rows extending longitudinally along the device; A stent device wherein along each of the rows, the interconnecting members alternate between the first orientation and the second orientation at each successive occurrence. (Item 2) Item 1, wherein the first coupling end and the second coupling end of each of the plurality of interconnecting members each include a bent portion. (Item 3) 3. The device of either item 1 or 2, wherein the number of interconnecting members between any two adjacent rings of the plurality of rings is equal to the number of repeating curved segments in each ring of the plurality of rings. (Item 4) 4. The device of any one of items 1 to 3, comprising three adjacent sets of rings, wherein a first set of rings includes a central ring and a second ring, and wherein the second set of rings includes the central ring and a third ring, and wherein the number of interconnecting members between the first set of rings of the plurality of rings is equal to the number of repeating curved sections in the second set of rings of the plurality of rings. (Item 5) 5. The device of any one of items 1 to 4, wherein the first coupling end and the second coupling end of each of the plurality of interconnection members are aligned by an azimuth angle. (Item 6) 6. The device according to any one of items 1 to 5, wherein the first coupling end and the second coupling end of each of the plurality of interconnection members are aligned in a circumferential direction. (Item 7) 7. The device according to any one of items 1 to 6, wherein each of the plurality of rings is independently radially expandable. (Item 8) 8. The device of claim 7, wherein the independent expandability of each of the plurality of rings occurs within a range of diameters between an operational deployed diameter and an initial diameter that is smaller than the operational deployed diameter. (Item 9) Item 9. The device of any of items 1-8, wherein the plurality of repeating curved sections form a generally sinusoidal pattern. (Item 10) 10. The device of any one of items 1 to 9, wherein peak-to-valley amplitude is substantially equal for each of the plurality of rings. (Item 11) 10. The device of claim 1, wherein the peak-to-valley amplitude is within a tolerance range of the average amplitude measured for each of the plurality of rings, the tolerance range being 20% ​​of the average amplitude, 15% of the average amplitude, 10% of the average amplitude, or 5% of the average amplitude. (Item 12) 11. The device of any one of items 1 to 10, wherein each of the plurality of curved sections has a substantially uniform width. (Item 13) Item 12. The device of item 11, wherein all of the plurality of curved sections have substantially the same substantially uniform width. (Item 14) 13. The device of any of items 1-12, wherein one or more of the plurality of interconnect members do not have a substantially uniform width. (Item 15) 11. The device according to any one of items 1 to 10, wherein each of the plurality of curved sections has a width within a tolerance range of an average thickness of the plurality of curved sections, the tolerance range being 20% ​​of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness. (Item 16) Item 15. The device of item 14, wherein all of the plurality of curved sections have widths within a tolerance range of the average thickness of all of the plurality of curved sections, the tolerance range being 20% ​​of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness. (Item 17) 16. The device according to any of items 1 to 15, further comprising a cover disposed over the stent device, thereby forming a covered stent. (Item 18) Item 17. The device of item 16, wherein the cover comprises one or more cover materials, one or more coatings, or both. (Item 19) Item 18. The device according to item 16 or 17, wherein the cover entirely covers the plurality of rings. (Item 20) 19. The device of items 16-18, wherein the cover comprises expanded polytetrafluoroethylene (ePTFE). (Item 21) 20. The device of any of items 1-19, wherein the plurality of rings are constructed from one or more of a non-biodegradable alloy, stainless steel, or cobalt chromium. (Item 22) 21. The device of any of items 1-20, wherein the stent device, when coated and expanded to an operable deployed diameter, exhibits a foreshortening of about 6% or less, about 3% or less, about 2% or less, about 1% or less, or about 0% or less. (Item 23) 22. The device of any of items 1-21, wherein the stent device having a covering exhibits about 0% foreshortening when expanded to an operational deployed diameter. (Item 24) 23. The device of any of items 1 to 22, wherein the stent device having a covering exhibits recoil of about 6.6% or less when the covered stent has an initial diameter of 1.6 mm and an expanded diameter of 5 mm. (Item 25) 23. The device of any of items 1-22, wherein the stent device having a covering exhibits recoil of about 7% or less when the covered stent has an initial diameter of 1.7 mm and an expanded diameter of 6 mm. (Item 26) 23. The device of any of items 1-22, wherein the stent device having a covering exhibits recoil of about 6.7% or less when the covered stent has an initial diameter of 1.8 mm and an expanded diameter of about 7 mm. (Item 27) 1. A stent device comprising: a stent comprising a plurality of radially expandable rings arranged in series along a common longitudinal axis and connected by a plurality of interconnecting members, each of the plurality of radially expandable rings comprising a plurality of repeating curved sections, each repeating curved section comprising peaks and valleys, the peaks and valleys of adjacent expandable rings having an angular offset such that the peaks of a first expandable ring are longitudinally aligned with the valleys of a second expandable ring adjacent to the first expandable ring; a cover formed from expanded polytetrafluoroethylene and having an inner layer and an outer layer, the cover encapsulating the stent to form a covered stent; Equipped with A stent device, wherein the covered stent device exhibits a foreshortening of about 6% or less when expanded to an operational deployed diameter. (Item 28) Item 28. The stent device of item 27, wherein the number of interconnecting members between adjacent expandable rings is equal to the number of valleys between each of the adjacent expandable rings. (Item 29) 29. The stent device of claim 27 or 28, wherein each of the interconnecting members has an extension portion, a first connecting end, and a second connecting end, and the first connecting end, the extension portion, and the second connecting end are combined in a first orientation or a second orientation, and the second orientation is substantially a mirror image of the first orientation. (Item 30) 30. The stent device of item 29, wherein the interconnecting members of a first set of two adjacent expandable rings are in the first orientation, the interconnecting members of a second set of two adjacent expandable rings are in the second orientation, and only one of the expandable rings of the second set of two adjacent expandable rings is shared with the first set of two adjacent expandable rings. (Item 31) Item 31. The stent device of item 30, wherein the interconnecting members are arranged in series along the length of the stent and form a sinusoidal shape with inflection points at or near where the interconnecting members connect to the expandable rings. (Item 32) 32. The stent device according to any one of items 27 to 31, wherein the covered stent device exhibits a foreshortening of about 3% or less when expanded to an operable deployed diameter. (Item 33) 32. The stent device according to any one of items 27 to 31, wherein the covered stent device exhibits a foreshortening of about 2% or less when expanded to an operable deployed diameter. (Item 34) 32. The stent device according to any one of items 27 to 31, wherein the covered stent device exhibits a foreshortening of about 1% or less when expanded to an operable deployed diameter. (Item 35) 32. The stent device according to any one of items 27 to 31, wherein the covered stent device exhibits about 0% or less foreshortening when expanded to an operational deployed diameter. (Item 36) 36. The stent device according to any one of items 1 to 35, wherein the operable deployed diameter is about 4 mm to about 8 mm, more preferably about 5 mm to about 7 mm. (Item 37) Item 37. The stent device according to any one of items 1 to 36, wherein each of the plurality of curved sections comprises one peak and one valley. (Item 38) 37. The stent device according to any one of items 1 to 36, wherein within the plurality of curved sections, the peaks and valleys of the plurality of curved sections are the only peaks and valleys within the plurality of curved sections. (Item 39) 1. A method of manufacturing a stent device, comprising: providing a plurality of generally cylindrical rings each formed by a plurality of repeating curved segments, each of the plurality of curved segments comprising a peak, a valley, and a transition region connecting the peak and the valley, each curved segment having a midpoint substantially halfway between the peak and the valley on the transition region, the plurality of rings being arranged in series along a longitudinal axis such that the peaks and valleys of each curved segment in each ring in the series are substantially mirror images of the peaks and valleys of a corresponding curved segment in an immediately adjacent ring; providing a plurality of interconnect members; Including, Each of the plurality of interconnecting members comprises: a first connecting end; a second connecting end opposite the first connecting end; an extension portion extending between the first connecting end and the second connecting end, wherein the first connecting end, the extension portion, and the second connecting end mate in a first orientation or a second orientation that is a substantial mirror image of the first orientation; Equipped with the first link end intersects the midpoint of the transition region of a curved section of one of the plurality of rings, and the second link end intersects the midpoint of a curved section of a different and immediately adjacent ring of the plurality of rings; the plurality of interconnect members are arranged in rows extending longitudinally along the device; along each of said rows, said interconnecting members alternate between said first orientation and said second orientation at each successive occurrence. (Item 40) Item 40. The method of item 39, wherein the first coupling end and the second coupling end of each of the plurality of interconnecting members each include a bend. (Item 41) 41. The method according to any one of items 39 to 40, wherein the number of interconnecting members between any two adjacent rings of the plurality of rings is equal to the number of repeating curved sections in each ring of the plurality of rings. (Item 42) 42. The method according to any one of items 39 to 41, wherein the first coupling end and the second coupling end of each of the plurality of interconnection members are aligned by an azimuth angle. (Item 43) 43. The method according to any one of items 39 to 42, wherein the first coupling end and the second coupling end of each of the plurality of interconnecting members are aligned in a circumferential direction. (Item 44) Each of the plurality of rings is independently radially expandable. 3. A method according to any one of the preceding claims. (Item 45) 45. The method of any of items 39 to 44, wherein the plurality of repeating curved sections form a generally sinusoidal pattern. (Item 46) 46. ​​The method according to any one of items 39 to 45, wherein the peak-to-valley amplitude is substantially equal for each of the plurality of rings. (Item 47) 46. ​​The method of any of items 39 to 45, wherein the peak-to-valley amplitude is within an acceptable range of an average amplitude measured for each of the plurality of rings, and the acceptable range is 20% of the average amplitude, 15% of the average amplitude, 10% of the average amplitude, or 5% of the average amplitude. (Item 48) Item 48. The method according to any one of items 39 to 47, wherein each of the plurality of curved sections has a substantially uniform width. (Item 49) 49. The method according to any one of items 39 to 48, wherein all of the plurality of curved sections have substantially the same substantially uniform width. (Item 50) 48. The method of any of items 39-47, wherein one or more of the plurality of interconnect members do not have a substantially uniform width. (Item 51) 48. The method according to any one of items 39 to 47, wherein each of the plurality of curved sections has a width within a tolerance range of an average thickness of the plurality of curved sections, the tolerance range being 20% ​​of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness. (Item 52) 52. The method of any one of items 39 to 47 and 51, wherein all of the plurality of curved sections have widths within a tolerance range of the average thickness of all of the plurality of curved sections, the tolerance range being 20% ​​of the average thickness, 15% of the average thickness, 10% of the average thickness, or 5% of the average thickness. (Item 53) 53. The method of any one of items 39 to 52, further comprising providing a cover over the stent device, the cover covering substantially the entire length of the plurality of rings. (Item 54) Item 54. The method of item 53, wherein the cover comprises expanded polytetrafluoroethylene (ePTFE). (Item 55) Item 54. The method of item 53, wherein the cover comprises one or more cover materials, one or more coatings, or both. (Item 56) 56. The method of any of items 39-55, wherein the plurality of rings are constructed from one or more of a non-biodegradable alloy, stainless steel, or cobalt chrome. (Item 57) A stent device comprising a plurality of radially expandable rings linked together by a plurality of interconnecting members arranged as shown in FIG. 3A. (Item 58) The stent device according to any of items 1 to 38 and 57, in any operable combination. (Item 59) 57. The method according to any of items 39 to 56, in any operable combination. (Item 60) 1. A method of installing a stent device, comprising: delivering a stent device according to any one of items 1 to 38 or 57 to a site; expanding the stent device from a first diameter to a second diameter greater than the first diameter; A method comprising: (Item 61) Item 61. The method of item 60, wherein the site is a lumen. (Item 62) Item 62. The method of item 61, wherein the lumen is a tube. (Item 63) 62. The method of claim 61, wherein the vessel is a blood vessel of a living or non-living mammal. (Item 64) 64. The method of any of items 60 to 63, wherein the expanding step occurs through the use of an inflatable balloon membrane. (Item 65) 65. The method according to any one of items 60 to 64, wherein the second diameter is an operational deployed diameter and the first diameter is less than half of the operational deployed diameter. (Item 66) Item 66. The method according to item 65, wherein the operable deployed diameter is about 4 mm to about 8 mm, more preferably about 5 mm to about 7 mm. (Item 67) 67. The method of any of items 60-66, wherein the covered stent device exhibits a foreshortening of about 6% or less when expanded to the second diameter. (Item 68) Item 68. The method of item 67, wherein the covered stent device exhibits a foreshortening of about 3% or less when expanded to the second diameter. (Item 69) Item 69. The method of item 68, wherein the covered stent device exhibits a foreshortening of about 2% or less when expanded to the second diameter. (Item 70) 70. The method of claim 69, wherein the covered stent device exhibits a foreshortening of about 1% or less when expanded to the second diameter. (Item 71) Item 71. The method of item 70, wherein the covered stent device exhibits about 0% or less foreshortening when expanded to the second diameter. [Brief explanation of the drawings]

[0028] These and other features of the present invention will be more fully understood by reference to the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a diagram of a prior art stent pattern. [Figure 2] FIG. 2 is a perspective view of an exemplary stent pattern illustrated in a set of three rings and arranged as a generally tubular stent, according to an exemplary embodiment of the present invention. [Figure 3A] FIG. 3A is a flattened view of the exemplary stent pattern of FIG. 2 arranged in sets of five rings, according to an exemplary embodiment of the present invention. [Figure 3B] FIG. 3B is a detailed view taken along box 300 of FIG. 3A. [Figure 3C] 3C-3E are cross-sectional views taken at section lines CC, DD, and EE, respectively, of FIG. 3B. [Figure 3D] 3C-3E are cross-sectional views taken at section lines CC, DD, and EE, respectively, of FIG. 3B. [Figure 3E] 3C-3E are cross-sectional views taken at section lines CC, DD, and EE, respectively, of FIG. 3B. [Figure 4] FIG. 4 is a cross-sectional view of a covered stent device according to an exemplary embodiment of the present invention. [Figure 5] FIG. 5 is a perspective view of the covered stent device of FIG. 4, according to an exemplary embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing the average shortening values ​​measured for various covered stent devices according to embodiments of the present invention that were made and tested. [Figure 7] FIG. 7 is a flattened view of a stent similar in design to the stent of FIGS. 2 and 3A that was tested for comparative purposes in accordance with aspects of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Various terms and definitions are used throughout this specification. The term "foreshortening" and the tools and practices for measuring stent dimensions are well understood in the stent art and can be found, for example, in ASTM F2081-06 (2013 Edition), entitled "Standard Guide for Characterization and Presentation of the Dimensional Attributes of Vascular Stents," and "Guidance for Industry and FDA Staff: Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems," issued April 18, 2010, by the Center for Devices and Radiological Health, Food and Drug Administration, U.S. Department of Health and Human Services.

[0030] The term "substantially a mirror image" as used in this application is broadly understood to mean that the shape conveyed by "mirror image" is essentially identical to the original shape, but is inverted by mirror symmetry. Any deviation in magnitude between the original shape and the reflected shape may be within the manufacturing tolerances of the original and the reflected shape, respectively.

[0031] The term "substantially intermediate" as used in this application is broadly understood to mean the midpoint within manufacturing tolerances.

[0032] Illustrative embodiments of the present invention relate to stents having structural designs that significantly reduce foreshortening after or during expansion to an operational diameter. As evidenced by the results of testing sample stents according to embodiments of the present invention performed herein, foreshortening values ​​of about 0% or less were obtained while maintaining low values ​​of recoil.

[0033] Specifically, a stent according to an illustrative embodiment of the present invention may include a plurality of generally cylindrical rings, each formed from a plurality of repeating curved segments. The rings may be arranged in series along the longitudinal axis, with each ring in the series being a substantial mirror image of the immediately adjacent ring. The rings may be interconnected by a plurality of interconnecting members and arranged in rows extending longitudinally along the stent. Each interconnecting member may include an extension extending between two connecting ends. The interconnecting members may assume a first orientation or a second orientation that is a substantial mirror image of the first orientation. The interconnecting members may connect to rings at midpoints of the curved segments. Along each row, successive interconnecting members alternate between the first orientation and the second orientation.

[0034] 2-7, in which like parts are assigned like reference numerals throughout, illustrate exemplary embodiments of stents and methods of manufacturing the same in accordance with the present invention. While the present invention will be described with reference to the exemplary embodiments illustrated in the drawings, it should be understood that many alternative forms can embody the invention. Those skilled in the art will recognize various ways to modify the parameters of the disclosed embodiments, such as size, shape, or type of elements or materials, in a manner that retains the spirit and scope of the present invention.

[0035] FIG. 2 shows a perspective view of a stent 210 having a stent pattern 211 according to an exemplary embodiment of the invention. FIG. 3A shows a top view of the stent pattern 211 in a flattened (unrolled) state. The stent 210 includes a plurality of generally cylindrical, independently expandable rings 212 arranged in series along a longitudinal axis 224. Each ring 212 can have a center point that lies on the longitudinal axis 224 such that all of the rings 212 are coaxial. Collectively, the plurality of rings 212 can form an elongated, generally cylindrical shape. Each ring 212 includes a plurality of alternating peaks 214 a and valleys 214 b, with each peak 214 a adjacent to two valleys 214 b and each valley 214 b adjacent to two peaks 214 a. The transition region 228 connects each peak 214a to its adjacent valley 214b, and each valley 214b to its adjacent peak 214a. Thus, each peak 214a connects to a transition region 228 on each side, leading to an adjacent valley 214b. Similarly, each valley 214b connects to a transition region 228 on each side, leading to an adjacent peak 214a. The transition region 228 may be uncurved or curved. In FIG. 2, only three rings 212 are shown for clarity. In FIG. 3A, six rings 212 are shown. Those skilled in the art will recognize that the stent 210 and stent pattern 211 can include more or fewer rings 212.

[0036] In addition to the peaks 214a and valleys 214b, the rings 212 are also formed from repeating units referred to herein as repeating curved segments 222. Each of the multiple repeating curved segments 222 includes a peak 214a and a valley 214b and a transition region 228 connecting the two. In the exemplary embodiment of FIG. 2, the stent pattern 211 includes six repeating curved segments 222 per ring 212. However, fewer or more repeating curved segments 222 may be included depending on the specific intended application and the dimensions of the target deployment site. It should be appreciated by those skilled in the art that the phrase "substantially repeating" in this application indicates that the units are repeating but are adaptable to minor interruptions within the repeating pattern. That is, the present invention is not intended to be limited to a strict, exact repeating pattern of curved segments. If a stent is fabricated that reproduces the repeating curved segment pattern described and claimed herein, but with one or more minor interruptions in the pattern, such a stent is considered to be within the scope of the present invention.

[0037] 2 and 3A , each ring 212 is a mirror image of any ring 212 adjacent to it in series. Thus, for any two adjacent rings 212, the peaks 214 a of one of the two adjacent rings 212 are circumferentially aligned (e.g., facing) with the valleys 214 b of the other of the two adjacent rings 212, and vice versa. In other words, the peaks 214 a and valleys 214 b of each of the repeating curved sections 222 are mirror images of the peaks 214 a and valleys 214 b of the corresponding repeating curved section 222 of the immediately adjacent ring 212. In other words, the peaks 214 a and valleys 214 b of a first ring are circumferentially out of phase with the adjacent ring by half the distance accommodated by the repeating curved section 222. In an alternative embodiment, each successive ring 212 is not only a mirror image, but is also an angularly displaced mirror image. For example, each ring 212 may be "rotated" with some amount of angular displacement relative to its adjacent ring 212. The amount of angular displacement by which successive rings 212 are rotated may be substantially uniform throughout the stent 210. In some embodiments, a coating process is used to coat the stent 210, imparting some angular displacement to successive rings 212.

[0038] The rings 212 are interconnected and secured to one another by a plurality of interconnecting members 216. Each interconnecting member 216 connects two adjacent rings 212. Each interconnecting member 216 includes two linking ends 218 and an extension portion 220. For each interconnecting member 216, the extension portion 220 extends between and connects the two linking ends 218. As one non-limiting example, each linking end 218 can be a bend (e.g., a generally "L"-shaped member), as illustrated in the exemplary embodiment of FIGS. 2, 3A, and 3B. Each linking end 218 contacts the ring 212 of the repeated curved section 222 at a midpoint 223 of the repeated curved section 222 (i.e., halfway between the peaks 214a and valleys 214b of the repeated curved section 222, on a transition region 228). For example, if the ring 212 generally forms an "s" shape or a sinusoidal shape defined by the equation y = A * sin(x), the interconnecting member 216 can connect to the ring 212 at a location corresponding to the zero-crossing point in the equation. As illustrated in FIGS. 3C-3E, both the interconnecting member 216 and the ring 212 can have a relatively thin, generally rectangular cross-section (e.g., with rounded edges and corners). In various embodiments, the cross-sectional width of each interconnecting member 216 at the intersection where it meets the transition region (see, e.g., FIG. 3C) may not be as wide as the corresponding cross-sectional width of the extension portion 220 of either or both of the interconnecting member 216 (see, e.g., FIG. 3D) and the transition region 228 (see, e.g., FIG. 3E). This helps promote more localized bending within the linking end 218 of the interconnecting member 216 than within the transition region 228 due to a higher bending stiffness within the transition region 228 than within the linking end 218. It should be noted that in some cases, the "halfway" location described above need not be the exact midpoint. For example, the "halfway" may be within a tolerance of the actual midpoint established between two reference points. In various examples, the "halfway" may be approximately within a 20% tolerance of the distance or length to which the midpoint is established. In other embodiments, the tolerance may be within a 15%, 10%, or even 5% or less tolerance of the distance to which the midpoint is established.

[0039] In contrast to the stent 110 of FIG. 1 , each interconnecting member 216 of the stent 210 of FIGS. 2 and 3A is in an “up-up” or “down-down” configuration (i.e., when viewed rotated 90 degrees clockwise in FIG. 3A ), with the linking ends 218 of a single interconnecting member 216 extending on the same side of the elongated portion 220 (e.g., the top or bottom, respectively) for substantially all of the interconnecting members 216 included in the stent 210. In other words, the two linking ends 218 of each individual interconnecting member 216 extend in the same circumferential direction (e.g., clockwise or counterclockwise). Furthermore, in the exemplary embodiment of FIGS. 2 and 3A , the number of interconnecting members 216 between any two adjacent rings 212 may be equal to the number of repeating curved sections 222 within each ring 212.

[0040] 2 and 3A, the two link ends 218 of each interconnecting member 216 are azimuthally or circumferentially aligned such that the line connecting the two link ends 218 is parallel to the longitudinal axis 224. Thus, the two link ends 218 can be connected at corresponding mirror-image locations along the repeating curved sections 222 on adjacent rings 212. Furthermore, each interconnecting member 216 can be positioned such that its length is substantially parallel to the longitudinal axis 224. The interconnecting members 216 form a plurality of rows 230 (see FIG. 3A), each substantially parallel to the longitudinal axis 224. The rows 230 extend longitudinally along the stent 210, and the number of rows 230 is equal to the number of repeating curved sections 222 included in one ring 212. The number of interconnecting members 216 may be one less than the number of rings 212 spanned by the rows 230. For example, FIG. 3A illustrates six adjacent rings 212 and five interconnecting members 216 .

[0041] The circumferential direction of the orientation of the two link ends 218 of each interconnect member 216 can vary for successive interconnect members 216 along each row 230. In the exemplary embodiment of FIGS. 2 and 3A , the interconnect members 216 in any single row 230 are arranged in an alternating fashion such that the interconnect members 216 continuously alternate between an “up-up” configuration and a “down-down” configuration. In other words, the directional orientation of the link ends 218 of successive interconnect members 216 in a row 230 alternates between a first orientation in which the link ends 218 face clockwise (see directional arrow 270) and a second orientation in which the link ends 218 face counterclockwise (see directional arrow 272). The first and second orientations (e.g., “up-up” and “down-down”) are substantially mirror images of each other. In the exemplary embodiment of FIG. 3A, the interconnecting members 216 located between any two adjacent rings 212 are all of the same configuration (“up-up” or “down-down”), and all of the linking ends 218 located between any two adjacent rings 212 face in the same circumferential direction (e.g., clockwise or counterclockwise).

[0042] Each interconnecting member 216 can have a variable, non-uniform width. Preliminary testing suggests that such a variable width feature of the interconnecting members 216 can strengthen the stent 210 and prevent foreshortening when a cover is provided. For example, the extension portion 220 can include a slight bulge in its center, such that the center width of the extension portion 220 of the interconnecting member 216 is the widest width of the interconnecting member 216, and the width at the linking end 218 is generally the smallest (w > w; see FIGS. 3C and 3D). In one exemplary embodiment, the width at the center of the extension portion 220 is approximately 1.5 times the size of the width at the linking end 218 of the interconnecting member 216. As a further non-limiting example, the ratio of the widest to the narrowest width of the interconnecting member 216 can be approximately 1.56.

[0043] For each ring 212, each of the plurality of curved sections 222 can have a substantially uniform width. In various embodiments, the width of the plurality of curved sections is within a tolerance range, e.g., 25% of the average width of the plurality of curved sections. In other embodiments, ranges such as within 20%, 15%, 10%, and 5% of the average width of the plurality of curved sections may also be applicable. Furthermore, the peaks 214a, valleys 214b, and transition regions 228 of the rings 212 can all have substantially the same substantially uniform width, and may have a width (e.g., w3) greater than the width of the connecting ends 118 of the interconnecting members 216. It has been discovered that providing the repeating curved sections 222 with the same uniform width does not increase foreshortening of the stent 210 during expansion with the cover. This is advantageous because such a uniform width allows for a smaller diameter of the stent 210 and more uniform compression when transitioned to the prolapsed state.

[0044] Furthermore, the peak-valley amplitude may be uniform across each ring 212. The peak-valley amplitude of each ring 212 can be uniform across all rings 212 or can vary across the rings 212. For example, two consecutive rings 212 in a stent 210 can have different peak-valley amplitudes from one another. "Peak-valley" amplitude is defined to have its conventional definition of the height of a repeating curved section 222 measured vertically from a peak 214a to a valley 214b, as will be recognized by those skilled in the art herein. It has been found that varying the peak-valley amplitude (e.g., changing the value of the peak-valley amplitude of a stent 210 or varying the peak-valley amplitude of a particular ring 212 in a stent 210) can affect the shortening characteristics of the stent 210. Thus, the peak-valley amplitude can be optimized, as will be recognized by those skilled in the art upon reading this specification.

[0045] According to one exemplary embodiment of the present invention, stent 210 is encapsulated in a covering to form a covered stent device 242. For example, FIG. 4 shows an illustrative embodiment of covered stent device 242. More specifically, FIG. 4 shows stent 210 of FIG. 3A encapsulated with covering 240, shown in cross-section along line AA in FIG. 3A . Covering 240 includes an outer layer 240a disposed on the outer surface of stent 210 and an inner layer 240b disposed on the inner surface of stent 210. The outer and inner layers 240a, 240b may be made from a single material (e.g., "folded" around the ends of stent 210) to form the outer and inner layers 240a, 240b. Alternatively, the inner and outer layers 240a, 240b may be made from separate materials.

[0046] 5 shows the covered stent device 242 of FIG. 4 in a perspective view. As can be seen, the stent 210 is hidden from view because it is completely encapsulated by the cover 240. The covered stent device 242 can generally be included in any number of different delivery devices and systems and used in a variety of clinical treatments and conditions (e.g., for the treatment of stenosed blood vessels). As one non-limiting and illustrative example only, the covered stent device 242 can be included in a balloon dilatation catheter assembly, as will be readily recognized by those skilled in the art. [Example]

[0047] Example 1 An example of a covered stent device 242 that was fabricated and tested is described below. In particular, an exemplary method was used to fabricate multiple covered stent devices 242. In Example 1 provided herein, the cover 240 was fabricated from expanded polytetrafluoroethylene (ePTFE).

[0048] The ePTFE covering was provided with a desired diameter. The ePTFE covering was fabricated according to conventional methods known to those skilled in the art (e.g., forming a PTFE tube, sintering a PTFE tube, etc.). The stent 210 according to Figures 2 and 3A was fabricated and provided with a desired range of diameters, such as a relatively small compressed diameter (e.g., for insertion through a patient's vasculature) to a relatively large diameter, such as an expanded diameter. The expanded diameter may be the operational deployed diameter or a diameter smaller or larger than the operational deployed diameter.

[0049] Stent 210 was fabricated using conventional manufacturing techniques known in the art (laser cutting, electropolishing, etc.) In the example provided herein, stent 210 was made from stainless steel 316LVM.

[0050] In the examples provided herein, the slight overlapping portion of ePTFE was positioned near the center of the length of the stent 210. However, as previously described herein, the slight overlapping portion can alternatively be positioned away from the center of the length. Positioning the overlapping portion off-center of the length of the stent 210 and closer to one end of the stent 210 in this manner has been found to result in slower expansion of the resulting covered stent device at that particular end during deployment of the resulting covered stent device. In other words, the slight overlapping portion of the ePTFE covering can be used to limit the rate of expansion of the resulting covered stent device, e.g., thereby providing greater timing control over expansion. Thus, depending on the particular dimensions of the affected target site (e.g., the intima and / or lesion being treated), it may be desirable in certain embodiments to have the overlapping portion of the ePTFE covering at a non-central longitudinal location to desirably affect the rate of expansion of the resulting covered stent device at that particular longitudinal location. In such embodiments, the non-central portions of the resulting covered stent device expand at a different (e.g., controlled or predetermined) rate or amount than the remainder of the resulting covered stent device. Exemplary locations for non-central longitudinal positions may include within 40% of the length of one of the ends of the stent. In other embodiments, locations may include within 30%, within 20%, or optionally within 10% of one of the ends of the stent.

[0051] In particular, different groups of covered stent devices 242 were manufactured, which were generally distinguishable by their lengths. In one group, a 16 mm length was provided. In a second group, a 24 mm length was used. The groups of stents were tested for performance characteristics and their performance data was measured. This data is presented below in Table I.

[0052] [Table 1]

[0053] Generally, all of the covered stent devices 242 represented in Table I above were fabricated to include six repeating curved sections 222 per ring 212. Each row in Table I represents data for a sample of 15 substantially identical covered stent devices 242. The 16 mm covered stent devices 242 were fabricated to include six rings 212. The 24 mm covered stent devices 242 were fabricated to include nine rings 212. As represented in Table I, in some cases, shortening values ​​of 0.20% were measured. In other cases, negative shortening values ​​were measured, indicating that the covered stent devices 242 actually extended during or after expansion.

[0054] In all tests, the covered stent device 242 was expanded to an operationally deployed diameter. As used herein, "operably deployed diameter" refers to the diameter at which a stent can be operationally deployed (expanded) to at least one target site. The data in Table I is further presented in the graph of FIG. 6. Specifically, the graph of FIG. 6 displays the average shortening achieved by each covered stent device 242, grouped by length. Thus, each shortening curve in FIG. 6 shows the shortening characteristics of a depicted covered stent device 242 over a particular range of deployed diameters for a particular initial length of the covered stent device 242.

[0055] Those skilled in the art will recognize alternative methods of making the covered stent device 242. Furthermore, it is understood that the dimensions selected for testing are illustrative and not limiting in any way. Similarly, those skilled in the art will recognize that the number of repeating curved sections 222 included per ring 212 can depend on the required compression profile, depending on the intended medical application, intended target site, etc. The number of rings 212 included can depend on the particular desired length. Other characteristics may also be varied, as those skilled in the art would recognize upon reading this specification.

[0056] Furthermore, many alternatives and modifications to the stent 210 are possible and will be recognized by those skilled in the art. For example, rather than assuming that all rings 212 of the stent 210 have the same substantially uniform peak-valley amplitude, one or more of the rings 212 can have a substantially uniform peak-valley amplitude that differs from the substantially uniform peak-valley amplitude of adjacent rings 212. Other alternatives are possible. However, those skilled in the art will recognize that such alternatives have not been specifically tested (within acceptable and understandable scope of the present invention) and therefore may not exhibit the described performance characteristics (e.g., recoil and / or shortening characteristics). Those skilled in the art will understand that seemingly minor structural differences in the lattice structure of a stent can substantially affect the operation and performance characteristics of that stent. Thus, alternative designs to the structures described herein that are considered to be within the scope of the present invention will have similar operation and performance characteristics to those of the present design. Example 2

[0057] For comparison purposes, several comparative stents 250, each having a slightly different structure than the stent 210 of FIGS. 2 and 3A, were coated using the same method described above and subsequently tested for performance. Specifically, the comparative stent 250 design used in this example is shown in a flattened, unrolled state in FIG. 7. To ensure that the comparative stent 250 provided a fair comparison with the covered stent device 242, the comparative stent 250 was tested for performance before coating, i.e., as a bare-metal stent. Specifically, the shortening and recoil of the comparative stent 250 when uncoated were measured. This data is presented in Table II below. As can be seen, the comparative stent 250 performed with minimal shortening and recoil when uncoated and functioning as a bare-metal stent. Notably, the average shortening values ​​were as low as 1.1% in some cases.

[0058] [Table 2]

[0059] Each row in Table II represents data for two or three substantially identical samples of Comparative Stents 250. Once the design effects characterizing Comparative Stents 250 were generally established (e.g., through testing of Comparative Stents 250 as bare metal stents), additional groups of Comparative Stents 250 were coated using the same method. After coating the Comparative Stents 250, the coated Comparative Stents 250 were subjected to the same shortening performance test. In particular, the shortening of the coated Comparative Stents 250 was measured. The resulting data is presented below in Table III.

[0060] [Table 3]

[0061] In testing, the coated comparative stents 250 presented in Table III were expanded to an operational deployed diameter of about 5 mm, about 6 mm, or about 7 mm. Each row in Table III represents data for either 15 or 16 samples of substantially identical coated comparative stents 250. As presented in Table III, an average shortening value of approximately 30% was measured for the coated comparative stents 250 having an initial length of 16 mm and expanded to a diameter of about 7 mm. For comparison, the 16 mm long stent design of the present invention used in Example 1 resulted in a shortening value of about 6.8% when expanded to an operational deployed diameter of about 7 mm.

[0062] Thus, the stent design of the inventive covered stent device 242 of Example 1 performed significantly less foreshortening when covered compared to the stent design of the exemplary covered comparative stent 250 used in Example 2. These significantly different results were unexpected given the subtle structural differences between the covered comparative stent 250 and the covered stent device 242 according to an embodiment of the present invention. Thus, the data presented herein demonstrates that the covered stent device 242 according to an exemplary embodiment of the present invention performs at surprising and unexpected performance levels (e.g., as measured by foreshortening). Those skilled in the art will recognize that the data presented herein represent a significant and significant improvement over the prior art.

[0063] Numerous variations and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only, and is for the sole purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of construction may vary substantially without departing from the spirit of the present invention, and the exclusive use of all modifications that come within the scope of the appended claims is reserved. Within this specification, embodiments have been described to enable the specification to be clearly and concisely written, but it will be recognized that the embodiments can be combined or separated in various ways without departing from the invention. It is intended that the present invention be limited only to the extent required by the appended claims and applicable law.

[0064] It is also to be understood that the following claims are intended to cover all generic and specific features of the invention described herein and all statements of the scope of the invention that may reasonably be said to fall therein.

Claims

1. 1. A system of interconnecting members connecting a plurality of radially expandable rings of a stent device, comprising: a plurality of said interconnection members, each of said interconnection members comprising: a first connecting end directly connected to one of the radially expandable rings; a second connecting end opposite the first connecting end and directly connected to a second of the radially expandable rings; an extension portion connected between the first connecting end and the second connecting end, wherein the first connecting end, the extension portion, and the second connecting end mate in a first orientation or a second orientation that is a substantial mirror image of the first orientation; Equipped with each of the plurality of interconnecting members has a spindle shape with the width of each interconnecting member at the center of the elongated portion being at its widest point, each interconnecting member tapering along its length in both directions from the center of the elongated portion, the first connecting end forming a first end of the spindle shape, and the second connecting end forming a second end of the spindle shape; A system of interconnected components.

2. 10. The system of interconnecting members of claim 1, wherein the interconnecting members prevent foreshortening of the stent device by more than 3% when the stent device is expanded to an operational deployed diameter.

3. 10. The system of interconnecting members of claim 1, wherein the interconnecting members prevent foreshortening of the stent device by more than 2% when the stent device is expanded to an operational deployed diameter.

4. 10. The system of interconnecting members of claim 1, wherein the interconnecting members prevent foreshortening of the stent device by more than 1% when the stent device is expanded to an operational deployed diameter.

5. The system of interconnecting members of claim 1 , wherein the interconnecting members prevent greater than 0% foreshortening of the stent device when the stent device is expanded to an operational deployed diameter.

6. 10. The system of interconnection members of claim 1, wherein the first and second coupling ends of each interconnection member form a pair of elbows extending in the same circumferential direction about the stent device relative to that interconnection member.

7. The system of interconnection members of claim 1, wherein the first and second connecting ends of each interconnection member are each formed as a pair of elbows aligned by an azimuth angle, whereby a straight line connecting each pair of elbows is parallel to the longitudinal axis of the stent device.

8. The interconnection member system of claim 7 , wherein the extension portion extends along a straight line parallel to a longitudinal axis of the stent device.

9. 2. The system of interconnecting members of claim 1, wherein the interconnecting members are arranged in a plurality of rows extending longitudinally along the stent device, the interconnecting members in each row all being arranged in either the first orientation or the second orientation, and the rows are arranged such that the interconnecting members in each successive row alternate between the first orientation and the second orientation.

10. The interconnection member system of claim 1 , wherein the interconnection member is encapsulated by a biocompatible material.

11. The interconnection member system of claim 10, wherein the biocompatible material is an expanded polytetrafluoroethylene (ePTFE) material.

12. an interconnecting member connecting the first radially expandable ring and the second radially expandable ring of the stent device, a first connecting end directly connected to the first ring; a second connection end opposite the first connection end and directly connected to the second ring, the first connection end and the second connection end forming a pair of elbows, the pair of elbows (i) each extending in the same circumferential direction about the stent device, and (ii) each aligned azimuthally, whereby a first line connecting each pair of elbows is parallel to a longitudinal axis of the stent device; and an extension portion connected between the first connecting end and the second connecting end and extending along a second straight line parallel to a longitudinal axis of the stent device; Equipped with the interconnecting members have a spindle shape with the width of each interconnecting member at the center of the elongated portion being at its widest point, each interconnecting member tapering along its length in both directions from the center of the elongated portion, the first connecting end forming a first end of the spindle shape, and the second connecting end forming a second end of the spindle shape; Interconnecting members.

Images