Compressible resilient fabric, devices, and methods

A compressible resilient fabric can include a ground layer of knitted yarn, and a loop layer comprising a plurality of loops of yarn, each loop having a point knit into the ground layer. The fabric can be compressible from an non-compressed configuration, in which each loop has an apex extending substantially perpendicularly outward from the ground layer, into a compressed configuration, in which each loop is collapsed onto the ground layer. The fabric can further be resilient so as to substantially resume the non-compressed configuration when compression is relieved. The loop layer yarn can include a multifilament yarn having a high denier per filament ratio. The ground layer yarn can include a yarn shrinkable substantially more than the loop layer yarn. The loops can be densely knit so as to support the extension of the loops outward from the ground layer.

FIELD OF THE INVENTION

The present invention relates to compressible resilient fabric, devices including a compressible resilient fabric, and methods for making and/or using a compressible resilient fabric and/or device having a compressible resilient fabric.

BACKGROUND

Medical devices such as vascular and endovascular grafts and stent-grafts can include fabric components that function to promote sealing of the device to the lumen or structure in which it is implanted. Insertion of such devices and fabric components into target sites can require that the fabric be compressed and collapsed so as to be placed inside a delivery catheter or cannula. When such a device having a fabric component is inserted to a target site and the delivery catheter is removed, at least the fabric component is often expected to rebound to approximately its original shape, structure, and dimensions. Regaining its original shape, structure, and dimensions is important to achieve an adequate seal between the exterior of the device and the lumen or structure in which it is implanted. This is critical because any gaps or voids between the device and the implant site can prevent a reliable seal, which can lead to complications and/or device failure. The ability of such a fabric component to regain its original shape, structure, and dimensions after being compressed and implanted can often depend on the fabric having sufficient resiliency.

In some applications, medical devices comprising fabric and designed for insertion into vessels or ducts may be stored in a compressed, or collapsed, configuration for extended periods, for example, a number of months, before use. When stored in sterile packaging, such devices are secluded from exposure to ambient air. In such devices stored for prolonged periods in a compressed state and without exposure to ambient air, recovery of fabric to its original shape and dimensions can be adversely affected. In addition, some implantable medical devices can be stored in fluid media over various periods of time. Fabric components of such medical devices can absorb fluid media in which they are packaged and stored. When medical device fabric absorbs fluid media, the fabric may be lose some resiliency for regaining its original shape and dimensions when deployed.

Thus, there is a need for a fabric that can be compressed for ease of delivery to an implant site and that has sufficient resiliency to regain its original shape, structure, and dimensions when implanted. There is a need for such a fabric that can avoid the loss of performance characteristics during storage prior to use.

SUMMARY

The present invention can include embodiments of a compressible resilient fabric, devices including a compressible resilient fabric, and methods for making and/or using a fabric and/or device having a compressible resilient fabric.

In an illustrative embodiment, a compressible resilient fabric can include a ground layer of knitted yarn, and a loop layer comprising a plurality of loops of yarn, each loop having a point knit into the ground layer. The fabric can be compressible from a non-compressed configuration, in which each loop has an apex extending substantially perpendicularly outward from the ground layer, into a compressed configuration, in which each loop is collapsed onto the ground layer. The fabric can be resilient so as to substantially resume the non-compressed configuration when compression is relieved.

In some embodiments, the loop layer yarn can comprise a multifilament yarn having a high denier per filament ratio. For example, the loop layer yarn can comprise a multifilament yarn having 5-20 denier per filament. In some embodiments, the loop layer yarn can comprise a total denier of 60-70. In some embodiments, the ground layer yarn can comprise a yarn shrinkable substantially more than the loop layer yarn. For example, the ground layer yarn may comprise a yarn shrinkable about 40-60%, and the loop layer yarn can comprise a yarn shrinkable about 7-8%. In some embodiments, the loops can be densely knit so as to support the extension of the loops outward from the ground layer.

Some embodiments of the present invention can include a device comprising a substantially tubular inner member, and an intraluminal sealing member attachable to an exterior of the inner member. The sealing member can include a ground layer of knitted yarn and a loop layer comprising a plurality of loops of yarn, each loop having a point knit into the ground layer. The sealing member can be compressible from an non-compressed configuration, in which each loop has an apex extending substantially perpendicularly and radially outward from the ground layer, into a compressed configuration, in which each loop is collapsed onto the ground layer. The sealing member can further be resilient so as to substantially resume the non-compressed configuration when compression is relieved, for example, after the device is implanted into a lumen in a human or animal body. The intraluminal sealing member can be adapted to promote sealing between the inner member and a lumen wall. In some embodiments, the inner member can comprise a stent.

Some embodiments of the present invention can include a system and/or kit. Such a system and/or kit can include a compressible resilient fabric and/or devices including a compressible resilient fabric as described herein.

Some embodiments of the present invention can include a method of making a compressible resilient fabric and/or devices including a compressible resilient fabric. Such a method can include knitting a ground layer of yarn and a loop layer comprising a plurality of loops of yarn, each loop having a point knit into the ground layer. The method can further include washing the fabric in about 90 degree C. water. The method can further include drying the fabric at about 60-65 degrees C., which further shrinks the fabric. In the fabric and/or device made by such a method, the fabric can be compressible from a non-compressed configuration, in which each loop has an apex extending substantially perpendicularly outward from the ground layer, into a compressed configuration, in which each loop is collapsed onto the ground layer. The fabric can further be resilient so as to substantially resume the non-compressed configuration when compression is relieved.

Features of a fabric, device, system, kit, and/or method of the present invention may be accomplished singularly, or in combination, in one or more of the embodiments of the present invention. As will be realized by those of skill in the art, many different embodiments of a fabric, device, system, kit, and/or method according to the present invention are possible. Additional uses, advantages, and features of the invention are set forth in the illustrative embodiments discussed in the detailed description herein and will become more apparent to those skilled in the art upon examination of the following.

DETAILED DESCRIPTION

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the described embodiments are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, for example, 5.5 to 10. Additionally, any reference referred to as being “incorporated herein” is to be understood as being incorporated in its entirety.

For the purposes of this specification, terms such as “forward,” “rearward,” “front,” “back,” “right,” “left,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a loop” is intended to mean a single loop or more than one loop.

The present invention can include embodiments of a compressible resilient fabric, devices including a compressible resilient fabric, and methods for making and/or using a fabric and/or device comprising a compressible resilient fabric. Some embodiments of compressible resilient fabrics, devices, and methods according to the present invention may be useful for medical applications, for example, a stent comprising an intraluminal sealing member.

For purposes herein, “compressible” is defined as the ability of the fabric or intraluminal sealing member to be compressed from a relatively larger, expanded configuration to a relatively smaller, compressed configuration. For example, the fabric and/or intraluminal sealing member can be compressed from its original non-compressed configuration to the compressed configuration. In some embodiments, the entire dimension of the fabric along its length and width can be compressed. For purposes herein, “resilient” is defined as the ability of the fabric or intraluminal sealing member to recover from the compressed configuration to substantially its original shape, structure, and dimensions as in the non-compressed configuration.

In an illustrative embodiment, as shown inFIGS. 1-3, a compressible resilient fabric10can include a ground layer20of knitted yarn, and a loop layer30comprising a plurality of loops32of yarn31, each loop32having a point33knit into the ground layer20. The fabric10can be compressible from a non-compressed configuration40, in which each loop32has an apex34extending substantially perpendicularly outward42from the ground layer20, into a compressed configuration41, in which each loop32is collapsed onto the ground layer20. The fabric10can be sufficiently resilient so as to substantially resume the non-compressed configuration40when compression is relieved.

In some embodiments, the loop layer yarn31can comprise a multifilament yarn31having a high denier per filament ratio. For example, the loop layer yarn31can comprise a multifilament yarn31having 5-20 denier per filament. In some embodiments, the loop layer yarn can comprise a total denier of 60-70.

In some embodiments, the ground layer yarn can comprise a yarn substantially more shrinkable than the loop layer yarn31. For example, the ground layer yarn may comprise a yarn shrinkable about 40-60%, and the loop layer yarn31can comprise a yarn31shrinkable about 7-8%.

In some embodiments, the loops32can be densely knit so as to support the extension of the loops32outward from the ground layer20. For example, in certain embodiments, the loop layer30can include two loops32in every four courses of the ground layer20. In particular embodiments, the loop layer30can include between about 600 and about 750 loops32per square inch of the fabric10. In some embodiments, each loop32can have a substantially uniform height43in the non-compressed configuration40.

In the non-compressed configuration40, some embodiments of the fabric10can have a thickness43of about 1-5 mm. In the compressed configuration41, some embodiments of the fabric10can have a thickness44of about 0.004-0.008 inches. Thus, some embodiments of the fabric10can be compressed into a very thin profile for insertion to a target site in a location in a body, and recover to substantially its original non-compressed configuration40when positioned in the location and compression is relieved.

In some embodiments, the loops32can be constructed as “unitary” with the ground layer20. A “unitary” construction means that loops32are knit in a set repeat pattern so as to provide a uniform density. With a uniform density, gaps and voids in the knit pattern can be avoided. In some embodiments, the loops32can be constructed as “integral” with the ground layer20. An “integral” construction means that the loops32are knit simultaneously with and into the ground layer20. In some embodiments, the apex34of the loops32can be substantially erect, or perpendicular42to the face side, or technical face, of the ground layer20of the fabric10.

The fabric10may be compressed from its original non-compressed configuration40into the smaller, compressed configuration41by employing, for example, a mechanical crimping apparatus (not shown) designed for reducing the overall size of an intraluminal medical device50. Once crimped to the smaller size, the fabric10(and device) can be loaded into a delivery catheter. When a compressive pressure, such as the wall of a delivery catheter, is removed from the compressible resilient fabric10and/or medical device50comprising the fabric10, the fabric10can recover from the compressed configuration41to substantially its original non-compressed, or expanded, configuration40. Such recovery to substantially the original non-compressed configuration40can include return of the loops32to approximately the original, non-compressed loop, or pile, height43and other dimensions and shape.

Such self-recovery can be facilitated by various aspects of the present invention, as described herein. For example, in some embodiments, resilient recovery of the loops32to the non-compressed configuration40, including their non-compressed loop height43, can be provided at least in part by loop yarns31having higher denier per filament and relatively fewer filaments of yarn31. In some embodiments, resilient recovery of the loops32to the non-compressed configuration40can be provided at least in part by the ground layer yarns having substantially higher shrinkage capacity than the loop layer yarns31, which can cause the loops32to be tightly held in the ground layer20when the fabric10is heated. In some embodiments, resilient recovery of the loops32to the non-compressed configuration40can be provided at least in part by each loop32being integrally knit into the ground layer20, thereby providing tightly held loops32that tend to extend in an upright manner42away from the ground layer20. In some embodiments, resilient recovery of the loops32to the non-compressed configuration40can be provided at least in part by the loops32being densely knit into the ground layer20so as to enhance the stability of the loops32in their outwardly extended position42. In some embodiments, resilient recovery of the loops32to the non-compressed configuration40can be provided at least in part by thermoset memory of the fabric10, as described herein.

The “point”33of the loop32is the portion of the loop32that is integrally knit into the ground layer20. The “apex”34of the loop32is the portion opposite the point33of the loop32that extends outwardly away from the ground layer20.

Due to the resilient recovery property of embodiments of the fabric10of the present invention, each loop32can stand up by itself from its point33knitted to the ground layer20. Accordingly, in the non-compressed configuration40, the dense, extended loops32in the loop layer30of the fabric10can provide a consistent height43and contour. In this manner, the loop layer30can have a consistent contact with the interior wall of a vessel, duct, or other anatomical structure along the length and width of the fabric10. Such consistent contact with an adjacent vessel, duct, or other anatomical structure can enhance clotting and prevention of fluid flow between the exterior of an implanted device50such as the stent53and the vessel, duct, or other anatomical structure.

In some embodiments, the loop layer yarn31can comprise a multifilament yarn31having a high denier per filament ratio. “Multifilament” is defined as a manufactured fiber yarn composed of many fine filaments. Multifilament yarn31is desirable in some embodiments of the present invention due to the greater surface area exposed to a target location provided by multiple filaments in the yarn31. In applications in which the fabric10is utilized in vascular implantation, for example, the multifilament loop yarn31can promote enhanced cellular ingrowth and encapsulation to promote clotting and fixation of the fabric10to a vessel wall. Lower denier filament yarns, such as those used in conventional medical textiles, provide increased surface area but generally fail to exhibit sufficient recovery or resiliency from compression (due to limited memory retention) to provide optimal sealing between an implantable device and an adjacent anatomical structure, such as a vessel wall.

The stability and resilience of the fabric10, and in particular the loops32, can be related to the denier per filament ratio (dpf) in the multifilament loop yarn31. “Denier” is defined as the weight per unit length of yarn. Denier is numerically equal to the weight, in grams, of 9,000 meters length of yarn. The lower the denier, the lighter and finer the yarn. The higher the denier, the heavier and more coarse the yarn. “Denier per filament” (dpf) is defined as the size of each filament in a multifilament yarn equal to the total yarn denier divided by the number of filaments. The lower the dpf ratio, the harder it is for the loops32to spring back to their original configuration40. Conversely, the higher the dpf ratio, the easier it is for the loops32to recover to the non-compressed configuration40. Conventional medical device fabrics may comprise yarn having a total denier of about 150 and about 96 filaments, for a relatively low denier per filament (dpf) ratio of about 1.56.

In some embodiments of the compressible resilient fabric10of the present invention, the loop layer yarn31can have a total denier of about 60-70 denier and a relatively high denier per filament (dpf) ratio of about 5-20. That is, the denier per filament ratio in loop layer yarn31in the compressible resilient fabric10can be about 5-20 dpf, or about three to ten times greater, and the number of filaments can be about 40-50% less, than in conventional medical device fabric. In certain embodiments, the total denier for the loop yarn31in the compressible resilient fabric10can be less than about 60, for example, as low as about 10-15 denier, depending on the particular application for the fabric10.

In addition to providing more stable loops32having greater resiliency, the higher denier per filament yarn31in the fabric10can provide loops32that are more compressible than conventional fabric having lower denier per filament yarn. It was discovered in experimentation that two layers of multifilament loop yarn31having a total denier of about 60-70 allows a compressed fabric thickness45of about 0.008 inches. This degree of compressibility was found to be sufficient for utilization in medical device applications. In addition, multifilament loop yarn31having a total denier of about 60-70 was found to provide sufficient resilience for the loops32to recover substantially their non-compressed configuration40having a thickness between about 1 mm and about 2 mm of when compression was relieved.

Fluid media may have an impact on resiliency and/or uniformity of resiliency of the fabric10. Yarns having a relatively lower denier per filament ratio tend to absorb more fluid from fluid media in which they are packaged than yarns having a relatively high denier per filament ratio. Absorption of fluid from packaging media can cause the yarns to increase in volume, resulting in less resiliency when a compressive force is released from the fabric10. Therefore, some embodiments of the compressible resilient fabric10of the present invention comprising high denier per filament yarn31may absorb less fluid from packaging media, and the resiliency of such fabric10may thus be less adversely affected by fluid media, than conventional medical device fabrics.

In some embodiments, yarn in the ground layer20can have heat shrinkage rates, or shrinkability, up to 40% to 60% of the length and width of the unprocessed ground layer20. Such high rates of shrinkage in the yarn in the ground layer20can cause the courses and wales in the ground layer20to move closer together. In some embodiments, the yarns in the ground layer20can be under a higher tension than the yarns31in the loop layer30. A tighter ground layer20can provide more densely positioned loops32, thereby helping the loops32stand up and extend outwardly from the ground layer20. As a result, the dense positioning of the loops32can help stabilize the loops32. In this manner, the loops32can be securely positioned for consistent functionality after the compressible resilient fabric10is implanted within a patient and the fabric10is expanded to the non-compressed configuration40. That is, when the compressive force is removed from the fabric10, the loops32can recover, or resiliently reposition, to approximately their original, non-compressed height43, which can be a substantially uniform height43. Such a recoverable, substantially uniform loop layer height43can be particularly useful in medical applications in which a device may not completely conform to the contours of an anatomical structure in which it is implanted.

As described herein, the fabric10can be washed, dried, and heated during fabrication in order to shrink the high shrinkage ground layer yarn so as to cause the loop layer yarns31to stand up more effectively. A higher tension ground layer20can cause the loop points33to be tightly packed and the loop apices34to be at the greatest possible distance from the surface of the ground layer20, thereby providing maximum loop height43.

In particular embodiments, the loop yarn31can be a synthetic yarn, for example, a polyester yarn, with a heat shrinkage rate of between about 5% and about 8%. Maintaining the heat shrinkage rate of the loop yarn31in such a narrow range can provide shrinkage control of the loops32so that the compressibility, resilience, and other properties of the finished fabric10can be more consistent and predictable. Alternatively, a polyester yarn having a heat shrinkage rate in a broader range, such as between about 2% and about 10%, may be utilized for the loop yarn31. When using such a yarn having a broader range of heat shrinkage rate, finish processing can be varied to control the compressibility, resilience, and other properties of the finished fabric.

Embodiments of the compressible resilient fabric10and/or device50can comprise various materials. Many synthetic materials can be utilized to promote thrombogenesis when implanted as an intraluminal sealing device50. For example, nylon and/or polyolefins can serve as thrombogenic material(s) useful in the intraluminal sealing device50. In certain embodiments, polyester may be utilized for the ground layer20and/or the loop layer30yarn(s)31. In particular embodiments, different polyester yarns may be used in the ground layer20and loop layer30. Polyester is known to be well-adapted for promoting tissue in-growth in and around the yarn.

In alternative embodiments, the compressible resilient fabric10can be fabricated with dissolvable materials. Such dissolvable materials can include, for example, polyglycolic acid (PGA) and/or ploylactide acid (PLA). Depending on the particular application, the compressible resilient fabric10can be fabricated with dissolvable materials alone or in combination with non-dissolvable materials, such as polyester.

In the compressed configuration41, the fabric10can have a thickness44in the range of about 0.004-0.008 inches. Such a thin compressed configuration41can allow the fabric10to be easily inserted into a delivery catheter along with an intraluminal medical device, such as the device50. The compressed thickness44of the fabric10can be affected by various factors, including, for example, the type of yarn, the porosity of the ground layer20, and the density and height43of the loop layer30.

For example, in the non-compressed, or expanded, configuration40, the ground layer20can be very thin, for example, in the range of about 0.05-0.1 mm in height. The loops32can have a height43from the ground layer20of about 1-3 mm. In certain embodiments, the loop height43can be greater than 3 mm, depending on the size of the implantable device (for example the device50) to which it is attached relative to the size and configuration of the vessel into which the device50is implanted. For example, if the design of the implantable device50, such as the stent53, is inserted into a particularly tortuous vessel and leaves a 4-5 mm gap between the exterior surface of the device50and the wall of the vessel into which it is implanted, the height43of the loops32can be 4-5 mm.

The compressibility and/or resiliency in the compressible resilient fabric10needed for particular applications can vary. For example, in some clinical situations, compressibility may be of greater concern in order to compress the fabric10or device50comprising such fabric10into a small enough delivery catheter to reach a target implant site. In other situations, resiliency may be a more important consideration for fuller recovery of the loops32to their non-compressed height43so as to provide a tighter seal between the device50and the vessel wall. That is, in some embodiments of the present invention, the fabric10can be constructed to provide an optimized balance between a sufficiently low number of loops32and/or height/density for adequate compressibility and a sufficiently high number of loops32and/or height/density for resilient recovery. Such balanced loop density and height43can be optimized for particular applications, for example, a heart valve or for a stent-graft for an aneurysm.

The compressibility and recovery of embodiments of the fabric10from the compressed configuration41to its substantially original non-compressed configuration40can be affected by a variety of factors. Such factors can include the type of yarn, the denier per filament of yarn, the fabric construction, and the method of fabrication, among others. For example, in some embodiments, the ground layer20can have a porosity that can provide some space into which the loops32can be compressed. In some embodiments, the loops32can be held tightly and/or densely packed on the ground layer20. In some embodiments, the loops32can be sufficiently thin to allow packing in a compressed state and/or sufficiently thick to allow sealing with clots. In particular embodiments, the yarn in the ground layer20can comprise about two-thirds of the fabric volume, and the yarn31in the loops32can comprise about one-third of the fabric volume.

Some embodiments of the present invention can include a device50, as shown inFIG. 4, comprising a substantially tubular inner member51, and an intraluminal sealing member52attachable to the exterior of the inner member51. In some embodiments, the inner member51can comprise an implantable medical device, for example, a stent53.FIG. 3illustrates a cross-section of the fabric10(or sealing member52) in a tubular configuration, as may be applied to the inner member51. The sealing member52, or fabric10, may be attached to the tubular inner member51using various techniques. For example, the sealing member52, or fabric10, may be attached to the tubular inner member51with an adhesive material, by stitching the sealing member52, or fabric10, to the inner member51, or by other methods.

The sealing member52can include the ground layer20of knitted yarn and a loop layer30comprising a plurality of loops32of yarn31, each loop32having a point33knit into the ground layer20. The sealing member52can be compressible from a non-compressed configuration40, in which each loop32has an apex34extending substantially perpendicularly and radially outward42from the ground layer20, into a compressed configuration41, in which each loop32is collapsed onto and/or into the ground layer20. The sealing member52can be resilient so as to substantially resume the non-compressed configuration40when compression is relieved, for example, after the device50is implanted into a lumen in a human or animal body. The intraluminal sealing member52can be adapted to promote sealing between the inner member52and a lumen wall.

As shown inFIGS. 3 and 4, the implantable device50and the inner member51can be tubular in shape. Such tubular embodiments can be utilized in cardiovascular applications, such as with a heart valve or stent-graft. In such applications, the intraluminal sealing member52can be formed, wrapped, or attached about the radially expanding inner member51. In this manner, when the device50is implanted in a target location, flow of blood between the exterior of the device50and the wall of the vessel can be restricted and/or prevented. When the device50is radially expanded, there can be gaps and/or voids between the implanted device50and the vessel wall because the flexibility of the device50may not completely conform to the contours of the vessel. The intraluminal sealing member52can fill those gaps and/or voids. Accordingly, the sealing member51, and/or fabric10, can function as an in vivo sealant or gasket for the expandable medical device50. In certain embodiments, the loops32can comprise a thrombogenic material, such as polyester, that can further enhance clotting by the sealing member52, or fabric10. In addition, the intraluminal sealing member52can serve as a frictional retention mechanism to help secure the implanted device50to the target location in the body.

In some embodiments of such a device50, the loop layer yarn31can comprise a high denier per filament multifilament yarn31. For example, the multifilament yarn31in the device50can have 5-20 denier per filament. In some embodiments, the loop layer yarn can comprise a total denier of 60-70. The high denier per filament yarn31can enhance the ability of the loops32to stand upright so as to extend substantially perpendicularly outward42from the ground layer20. Such structural support within the loops32can provide enhanced stability to the loops32to maintain their upright positioning42. In certain embodiments, each loop32can have a substantially uniform height43in the non-compressed configuration40. As a result, the loop layer30of the intraluminal sealing member52can provide a consistent contact, and thus a reliable seal, between the underlying tubular inner member51and the wall of a lumen into which it is implanted.

In some embodiments, the ground layer yarn of the intraluminal sealing member52can comprise a yarn that is substantially more shrinkable than the loop layer yarn31. For example, the ground layer20may comprise a yarn shrinkable about 40-60%, and the loop layer30may comprise a yarn31shrinkable about 5-8%. The loop yarn31and/or the ground yarn can comprise various yarns. A particularly useful type of yarn in either or both layers20,30, respectively, is a polyester yarn. The polyester yarn can be different in each of the ground and loop layers20,30, respectively.

In some embodiments of such a device, the loops in the intraluminal sealing member can be densely knit to further enhance the upright stability of the loop layer. For example, the loop layer can include two loops knit in every four courses of the ground layer. In certain embodiments, the loop layer can include between about 600 and 750 loops per square inch of the fabric.

In some embodiments of such a device50, the intraluminal sealing member52can be compressed from the non-compressed configuration40to the compressed configuration41. In the non-compressed configuration40, some embodiments of the sealing member52can have a thickness of about 1-5 mm. In the compressed configuration41, some embodiments of the sealing member52can have a thickness of about 0.004-0.008 inches.

In some embodiments of the present invention, the multifilament loops32can promote clot formation within the loops32. A typical clotting cascade can occur in which blood clots form first on the inside of the loops32and then progressively outwardly until a clot forms a solid connection between the fabric10and/or sealing member52and the adjacent anatomical structure, such as a vessel wall. In this way, the clot facilitated by the loop structure and size can help secure the fabric10and/or device50in place and prevent blood flow around the outside of the device50. The height of the loops32can vary, depending on the underlying device50, the target location for implantation, and the degree of loop compressibility desired. A greater height of the loops32provides a larger surface area for clot formation and can minimize dislodgement of the forming clots. An optimal loop height43can allow promotion of clot formation while allowing sufficient compressibility of the loops32.

In some embodiments, movement and positioning of the compressible resilient fabric10and/or device50can be monitored fluoroscopically or under CT visualization. For example, the compressible resilient fabric10can include radiopaque material such that positioning and expansion of the device50and the attached fabric10can be monitored. Radiopaque is defined as being opaque to radiation and especially x-rays. In certain embodiments, a plurality of radiographic markers (not shown) can be in communication with predetermined portions of the compressible resilient fabric10and/or implantable device50so that when the device50moves, movement and positioning of the markers—and the fabric10and/or device50in communication therewith—can be visualized.

Embodiments of the compressible resilient fabric10, device50, system, kit, and method as described herein can be utilized in medical applications, including, for example, in vascular and endovascular implants such as stents, stent-grafts, and heart valves. Some embodiments may be applicable for use in various other types of anatomical structures and locations, for example, in shunts between organs and/or in gastrointestinal, pulmonary, neurological, and/or other structures and locations of a human or animal body.

Embodiments of the compressible resilient fabric10and/or device50can have advantages over conventional fabrics and devices. For example, one advantage is that the fabric10and/or sealing member52can be sufficiently compressible for inserting into a target location and sufficiently resilient to recover to substantially its non-compressed configuration40when in the target location and the compression is relieved. As a result, the fabric10and/or sealing member52are adapted to promote sealing between the fabric10and/or sealing member52and an adjacent anatomical structure, such as a lumen wall. In certain embodiments, the compressible resilient fabric10and/or device50can provide frictional contact between the fabric10or device50and the adjacent anatomical structure. Such a frictional contact can help prevent blood flow around the fabric10and/or device50and provide a surface for clot formation to further secure the fabric10and/or device50in the desired implant position.

Another advantage of some embodiments of the compressible resilient fabric10and/or device50is that the loops32can have sufficient stability in the perpendicularly extended (upright) position42relative to the ground layer20to provide a uniform loop height43, and thereby consistent contact with an adjacent anatomical structure. Loop stability can be advantageously provided by various aspects of embodiments of the present invention. For example, the loops32can be stabilized in the outwardly extended position42by each loop32being integrally knit into the ground layer20, by knitting the loops32closely together in a dense pattern, by high denier per filament yarn31in the loops32, and by the ground yarn having a high shrinkage capacity that when shrunk causes the loops32to become more tightly packed.

Another advantage of some embodiments of the compressible resilient fabric10and/or device50is that loops comprising high denier per filament yarn can retain resiliency when stored in fluid media.

Some embodiments of the present invention can include a system and/or kit. Such a system and/or kit can include a compressible resilient fabric10and/or devices50including a compressible resilient fabric10as described herein. For example, some embodiments of such a system and/or kit can include the fabric10and/or intraluminal sealing member52comprising a ground layer20of knitted yarn, and a loop layer30comprising a plurality of loops32of yarn31, each loop32having a point33knit into the ground layer20. The fabric10and/or intraluminal sealing member52can be compressible from an non-compressed configuration40, in which each loop32has an apex34extending substantially perpendicularly outward42from the ground layer20, into the compressed configuration41, in which each loop32is collapsed onto the ground layer20. The fabric10can be resilient so as to substantially resume the non-compressed configuration40when compression is relieved.

The loops32in embodiments of the fabric10and/or intraluminal sealing member52can be stabilized in the outwardly extended position42by various means, including by each loop32being integrally knit into the ground layer20, by knitting the loops32closely together in a dense pattern, by high denier per filament yarn31in the loops32, and by the ground yarn having a high shrinkage capacity that when shrunk causes the loops32to become more tightly packed.

The system and/or kit may further comprise additional components, for example, a delivery catheter for a device that includes the fabric10and/or intraluminal sealing member52.

Some embodiments of the present invention can include a method of making a compressible resilient fabric10and/or devices50including the compressible resilient fabric10as described herein. For example, one such a method can include knitting the ground layer20of yarn and the loop layer30comprising a plurality of loops32of yarn31, each loop32having a point33knit into the ground layer20. In the fabric20and/or device50made by such a method, the fabric10can be compressible from the non-compressed configuration40, in which each loop32has an apex34extending substantially perpendicularly outward42from the ground layer20, into the compressed configuration41, in which each loop32is collapsed onto the ground layer20. The fabric10can further be resilient so as to substantially resume the non-compressed configuration40when compression is relieved. In some embodiments of a method, the loop layer30can be knit with a multifilament yarn31having 5-20 denier per filament and a total denier of 60-70. A high denier per filament yarn can increase the extensibility and stability of loop positioning.

Embodiments of the compressible resilient fabric10and/or intraluminal sealing member52of the present invention can be made utilizing warp knitting techniques, for example, on a double-bar raschel knitting machine. As used herein, “warp knitting” is defined as a method of knitting fabric out of one or more sets of yarn prepared as warps on beams. The yarns are fed through one or more guide bars to knitting needles that form the yarns into interlaced loops32. The guide bars move the yarns around the needles and from needle to needle to create the warp knit fabric. In warp knitting, there is simultaneous yarn-feeding and loop-forming action occurring at every needle in the guide bar during the knitting cycle. All needles in the needle bar are simultaneously lapped by separate guide bars. A “warp knit fabric” is a knit fabric in which the yarns generally run lengthwise but in a zigzag patterns, which forms loops32in two or more wales.

In one alternative warp knitting technique to form the high pile fabric10, a “dummy needle” can be used to fill a needle space on a knitting machine when no needle is required for the pattern. In another alternative warp knitting technique, yarn ends can be looped around a pole to help form a loop32into a particular size. Use of a “pole” or pile sinker can be helpful for knitting relatively larger loops32.

Warp knitting can be advantageous for making the compressible resilient fabric10and/or intraluminal sealing member52in that warp knitting decreases the risk of the fabric10or sealing member52from fraying and from unraveling when cut. Warp knitting provides a manufacturing process that can result in consistent quality of knitted products.

In some embodiments of the compressible resilient fabric10and/or intraluminal sealing member52, the loops32can be integrally knit with the ground layer20utilizing a stitch design that ensures the points33of the loops32are held tightly to the ground layer20. Such tight loop layer30—ground layer20knitting can help the loops32stand upright42away from the ground layer20surface, thereby contributing to the resilience of the loops32.

FIG. 5shows a knitting stitch diagram of one four-course repeat for one exemplary embodiment of the compressible resilient fabric10. The 3-2-1-0 designation inFIG. 5represents spaces between needles along the direction of the wales in the fabric10. Courses1-4are indicated along the left hand side of the diagram. In this knitting pattern, four guide bars (bars1-4) alternate between two needle beds. While bars3and4knit in their respective courses, bars1and2each knit once in every four-course repeat. Thus, bars1and2produce open stitch loops32in alternating courses, providing two loops32in every four course repeat. The stitch notation inFIG. 5designates the path of the yarn on each bar between the needles. For example, the yarn on bar1travels in course1starting in space1and forms loop ending in space0; stays in space0in courses2and3; and then moves to space1in course4. Since the yarn stays in the same space (space0) in courses2and3, an open stitch loop32is formed.

In some embodiments, selected guide bars from which the ground layer20is knit can be tightly spaced so as to knit the ground layer20more tightly to create a more densely packed loop layer30. In some embodiments of a method, the loop layer30can be knit having between about 600 and about 750 loops32per square inch of the fabric10.

Another embodiment of a method of making the compressible resilient fabric10and/or devices50can include pile knitting. In a pile knitted construction, the pile (for example, loops32) stand out substantially at right angles42from the technical back of the knitted ground layer20. As used herein, “pile” refers to yarns (for example, loops32) that stand away, or extend outwardly42, from the surface of the fabric10. Sinker loops or underlaps can be used to produce this effect. Such a technique can be varied by using a double needle bar knitting machine, and pressing off on the second set of needles to produce the pile surface layer. Point or looped pile can be produced on a double-bar raschel knitting machine by replacing the front bar needles by a point or pin bar around which the pile yarns are overlapped. Pile knitting can produce a high pile fabric that has resistance to unraveling similar to the ravel-resistance achievable with warp knitting. A pile knitting machine also has the ability to hold slack in a stitch to create the ground layer20having higher tension than the loops32, thereby further enhancing the stability of the extended loops32. Pile knitting can provide for variation in the size of the loops32, which can be customized by changing the size of the knitting elements.

Knitted constructions of the compressible resilient fabric10can provide loops32having greater extensibility than in other construction modalities, such as weaving. Enhanced loop extensibility can allow greater height43of the loops32and thus greater contact with a vessel wall and more surface area for blood to clot between the exterior surface of a device50to which the fabric10is attached and the interior wall of the vessel into which the device50is implanted. Knitting also offers the advantage of providing enhanced stretch and recovery, or resiliency, of the loops32. In addition, warp knitting can provide a more flexible process for making a tubular device50with the fabric10, while still providing for the fabrication of the ground layer20and the loop layer30.

Although knitting may be a preferred technique for making some embodiments of the compressible resilient fabric10, the fabric10can also be made by weaving. Weaving may be utilized to produce a high pile fabric having a highly stable ground layer20. In addition, a thinner and more flexible fabric10may be made by weaving, which can facilitate production of a tubular device50. In woven embodiments of the fabric10, the loops32can comprise floated yarns. Thus, woven embodiments of the present invention may provide the advantages of increased stability, while including a thinner fabric10.

Some embodiments of a method of making the compressible fabric10and/or intraluminal sealing member52can further include washing the fabric10or sealing member52in about 90 degree C. water. Washing the fabric10or sealing member52after formation can advantageously cause some shrinkage of the fabric10or sealing member52. It may be desirable to place the fabric10or sealing member52inside a protective housing such as a mesh covering or bag to protect the loops32from rigorous agitation or disturbance during washing. The wash can include use of detergent(s), softener(s), and/or other additives.

After washing, the fabric10or sealing member52can be dried at about 60-65 degrees C. The fabric10or sealing member52can be dried in a tumble dryer. Drying at this temperature can cause the fabric10or sealing member52to shrink further. The ground layer20and the loop layer30can each be knit with a yarn(s) having a different degree of shrinkability. For example, the ground layer yarn can be substantially more shrinkable than the loop layer yarn31. In one particular embodiment, washing and drying the fabric10and/or intraluminal sealing member52can shrink the ground layer20about 40-60% and shrink the loop layer30about 7-8%.

After the washing and drying processes, the fabric10or sealing member52can be thermoset in a dry oven. Such heat-setting can improve the memory of the fibers in at least the loop layer yarns31. In addition, heat-setting can create pockets in the ground layer20that allow the loops32to be compressed into areas within the ground layer20, resulting in a thinner fabric in the compressed configuration41.

Certain embodiments of a method of making the fabric10or sealing member52can further include stretching the fabric10or sealing member52in the width or course-wise direction prior to drying the fabric10or sealing member52so as to heat set the fabric10or sealing member52under tension. For example, in some embodiments, each of the yarn ends of the fabric10or sealing member52can be releasably attached to pins in a pin frame. The pins in the pin frame can secure the edges of the fabric10or sealing member52to stabilize the fabric10or sealing member52with an even tension throughout the fabric10or sealing member52in order to achieve a consistent degree of final shrinkage as the fabric10or sealing member52is being heat set. Stretching the fabric10or sealing member52in the heat-setting process can thus provide a desired orientation for memory by the fabric10or sealing member52once heat set.

Some embodiments of the present invention can include a method of using the compressible resilient fabric10and/or devices50including the compressible resilient fabric10as described herein. For example, one such a method can include utilizing the device50comprising the substantially tubular inner member51, such as the stent53, and the intraluminal sealing member52attachable to the exterior of the inner member51. The sealing member52can include the ground layer20of knitted yarn and the loop layer30comprising a plurality of loops32of yarn31, each loop32having a point33knit into the ground layer20. The sealing member52can be compressed from the non-compressed configuration40, in which each loop32has an apex34extending substantially perpendicularly and radially outward42from the ground layer20, into the compressed configuration41, in which each loop32is collapsed onto the ground layer20. After the device50is implanted into a lumen in a human or animal body and compression is relieved, the sealing member52can recover so as to substantially resume its non-compressed configuration40. The intraluminal sealing member52can be adapted to promote sealing between the inner member51and a lumen wall.

Although the present invention has been described with reference to particular embodiments, it should be recognized that these embodiments are merely illustrative of the principles of the present invention. Those of ordinary skill in the art will appreciate that a compressible resilient fabric10, device50, system, kit, and methods of the present invention may be constructed and implemented in other ways and embodiments. Accordingly, the description herein should not be read as limiting the present invention, as other embodiments also fall within the scope of the present invention.