Patent Description:
A stent may be configured to be positioned in a body lumen for a variety of medical applications. For example, a stent may be used to treat a stenosis in a blood vessel, used to maintain a fluid opening or pathway in the vascular, urinary, biliary, tracheobronchial, esophageal or renal tracts, or to position a device such as an artificial valve or filter within a body lumen, in some instances. In some cases, a stent may include anti-migration features in order to help anchor the stent in place in whichever body lumen the stent is placed. In some instances, forming these anti-migration features may be difficult to do accurately and repeatedly. Of the known medical devices and methods of manufacture, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices and methods of manufacture. Stents including anti-migration features are disclosed in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

A first aspect of the invention relates to a medical stent having a first end, a second end, and a central longitudinal axis extending from the first end to the second end, which comprises a plurality of first filaments each extending in a first helical path around the central longitudinal axis in a first direction and a plurality of second filaments each extending in a second helical path around the central longitudinal axis in a second direction. The plurality of first filaments are interwoven with the plurality of second filaments. The first helical path of at least one of the plurality of first filaments includes a circumferential offset disposed between the first end and the second end.

According to the invention, the at least one of the plurality of first filaments includes an anti-migration loop protruding radially outward from an outer surface of the medical stent at the circumferential offset.

The circumferential offset forms the anti-migration loop.

At least a portion of the anti-migration loop is oriented substantially perpendicular to the central longitudinal axis.

A portion of the anti-migration loop is angled toward the first end or the second end of the medical stent.

According to a preferred embodiment of the first aspect of the invention, interweaving the plurality of first filaments and the plurality of second filaments defines a plurality of intersection points.

According to a preferred embodiment of the first aspect of the invention, the first helical path of the at least one of the plurality of first filaments passes under a first one of the plurality of second filaments at a first end of the circumferential offset and passes under a second one of the plurality of second filaments at a second end of the circumferential offset.

According to a preferred embodiment of the first aspect of the invention, the first helical path of the at least one of the plurality of first filaments includes a plurality of circumferential offsets longitudinally spaced apart from each other between the first end and the second end.

According to a preferred embodiment of the first aspect of the invention, the first helical path of multiple first filaments of the plurality of first filaments each includes a circumferential offset disposed between the first end and the second end.

A second aspect of the invention relates to a mandrel for forming a medical stent comprising a cylindrical body and a plurality of protrusions extending radially outward from the cylindrical body. The plurality of protrusions define a plurality of first channels extending helically around the cylindrical body in a first direction and a plurality of second channels extending helically around the cylindrical body in a second direction. At least some of the plurality of protrusions may include a groove formed therein extending in a circumferential direction around the cylindrical body, the groove being oriented substantially perpendicular to the central longitudinal axis of the cylindrical body.

According to a preferred embodiment of the second aspect of the invention, the at least some of the plurality of protrusions including the groove formed therein are raised protrusions extending radially outward from the cylindrical body farther than a remainder of the plurality of protrusions.

According to a preferred embodiment of the second aspect of the invention, the groove is oriented substantially perpendicular to a central longitudinal axis of the cylindrical body.

According to a preferred embodiment of the second aspect of the invention, the groove connects adjacent first channels of the plurality of first channels.

According to a preferred embodiment of the second aspect of the invention, the at least some of the plurality of protrusions including the groove formed therein form a circumferential row of protrusions extending around the cylindrical body.

A third aspect of the invention relates to a method of manufacturing a medical stent comprising: using a mandrel comprising a cylindrical body and a plurality of protrusions extending radially outward from the cylindrical body, wherein the plurality of protrusions defines a plurality of first channels extending helically around the cylindrical body in a first direction and a plurality of second channels extending helically around the cylindrical body in a second direction, wherein at least some of the plurality of protrusions include a groove formed therein extending in a circumferential direction around the cylindrical body, the groove being oriented substantially perpendicular to the central longitudinal axis of the cylindrical body; and winding a plurality of first filaments around the mandrel within the plurality of first channels and winding a plurality of second filaments around the mandrel within the plurality of second channels such that the plurality of first filaments and the plurality of second filaments are interwoven to define a body of the medical stent. At least some of the plurality of first filaments may be wound over the at least some of the plurality of protrusions including the groove formed therein.

According to a preferred embodiment of the third aspect of the invention, winding at least some of the plurality of first filaments over the at least some of the plurality of protrusions including the groove formed therein forms a plurality of anti-migration loops extending radially outward from the body of the medical stent.

According to a preferred embodiment of the third aspect of the invention, each first filament wound over the at least some of the plurality of protrusions including the groove formed therein extends under one of the plurality of second filaments adjacent a first end of the groove and under an adjacent one of the plurality of second filaments adjacent a second end of the groove.

According to a preferred embodiment of the third aspect of the invention, each anti-migration loop extends radially outward from the body of the medical stent between two adjacent second filaments.

According to a preferred embodiment of the third aspect of the invention, the groove formed in the at least some of the plurality of protrusions extends in a circumferential direction around the cylindrical body.

According to a preferred embodiment of the third aspect of the invention, winding at least some of the plurality of first filaments over the at least some of the plurality of protrusions including the groove formed therein within the groove shifts those first filaments from one first channel to an adjacent first channel.

The invention may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which:.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the invention to the particular embodiments described.

The following description should be read with reference to the drawings, which are not necessarily to scale, wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings are intended to illustrate but not limit the claimed invention. Those skilled in the art will recognize that the various elements described and/or shown may be arranged in various combinations and configurations without departing from the scope of the disclosure. The detailed description and drawings illustrate example embodiments of the claimed invention. However, in the interest of clarity and ease of understanding, while every feature and/or element may not be shown in each drawing, the feature(s) and/or element(s) may be understood to be present regardless, unless otherwise specified.

<FIG> and <FIG> are schematic illustrations of a prior art stent <NUM>. The prior art stent <NUM> may be defined by and/or may have a central longitudinal axis <NUM> extending between a first end <NUM> and a second end <NUM>. The prior art stent <NUM> may include a body <NUM> defining an outer surface <NUM> that is generally cylindrical. The body <NUM> may extend from the first end <NUM> to the second end <NUM>. In a prior art stent <NUM> having flared end portions (not shown), the body <NUM> may extend between the flared end portions of the prior art stent <NUM>. The prior art stent <NUM> and/or the body <NUM> may include a plurality of first filaments <NUM> extending around the central longitudinal axis <NUM> in a first direction and a plurality of second filaments <NUM> extending around the central longitudinal axis <NUM> in a second direction.

<FIG> illustrates a portion of an example prior art mandrel <NUM> used to form the prior art stent <NUM>. The prior art mandrel <NUM> may include projections <NUM> extending radially outward from a mandrel body to define a plurality of first channels <NUM> and a plurality of second channels <NUM>. The outer surface of the mandrel body may define a base of the channels <NUM>/<NUM>. The plurality of first filaments <NUM> and the plurality of second filaments <NUM> may be disposed between the projections <NUM> within the channels <NUM>/<NUM> to form the prior art stent <NUM> such that the prior art stent <NUM> has a substantially uniform diameter and/or outer surface. <FIG> is a detailed view illustrating a portion of the prior art stent <NUM>, wherein the plurality of first filaments <NUM> and the plurality of second filaments <NUM> are interwoven to form a braided tubular member. The interwoven first filaments <NUM> and second filaments <NUM> may define the outer surface of the prior art stent <NUM>.

<FIG> and <FIG> schematically illustrate aspects of a medical stent <NUM> according the instant disclosure. The medical stent <NUM> has a first end <NUM>, a second end <NUM>, and a central longitudinal axis <NUM> extending from the first end <NUM> to the second end <NUM>. The medical stent <NUM> may include a tubular body <NUM> defining a lumen extending therethrough from the first end <NUM> to the second end <NUM>. The tubular body <NUM> may define an outer surface <NUM> of the stent <NUM>. In some embodiments, the body <NUM> may extend from the first end <NUM> to the second end <NUM>. In some embodiments, the medical stent <NUM> may include a flared first end (not shown) and/or a flared second end (not shown). In those embodiments, the body <NUM> of the medical stent <NUM> may extend from the first end <NUM> to the flared second end, from the flared first end to the second end <NUM>, or from the flared first end to the flared second end. Other arrangements are also contemplated.

The following description assumes the body <NUM> extends from the first end <NUM> of the medical stent <NUM> to the second end <NUM> of the medical stent <NUM>. In other configurations, the first end <NUM> and the second end <NUM> may be considered to refer to a first end of the body <NUM> and a second end of the body <NUM>, respectively. The body <NUM> of the medical stent <NUM> may have a generally constant and/or uniform outer diameter and/or outer surface <NUM>, however, as noted above, in some instances the body <NUM> may include one or more flared ends.

The tubular body <NUM> may be formed of a plurality of interwoven filaments, such as a plurality of braided filaments extending in helical directions while crossing over and under one another along the length of the tubular body to form a braided tubular framework. For instance, the medical stent <NUM> includes a plurality of first filaments <NUM> each extending in a first helical path around the central longitudinal axis <NUM> in a first direction (i.e., first helical direction) from the first end <NUM> toward and/or to the second end <NUM>. In some embodiments, the first direction may be clockwise. The medical stent <NUM> includes a plurality of second filaments <NUM> each extending in a second helical path around the central longitudinal axis <NUM> in a second direction (i.e., second helical direction) from the first end <NUM> toward and/or to the second end <NUM>. In some embodiments, the second direction may be opposite the first direction. In some embodiments, the second direction may be counterclockwise.

According to the invention, the first helical path of at least one of the plurality of first filaments <NUM> includes a circumferential offset disposed along the body <NUM> between the first end <NUM> and the second end <NUM>. For example, at least one of the plurality of first filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion.

In some embodiments, the first helical path of multiple first filaments of the plurality of first filaments <NUM> may each include a circumferential offset along the body <NUM> between the first end <NUM> and the second end <NUM>. In some embodiments, the first helical path of each and/or all of the plurality of first filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end <NUM> and the second end <NUM>. For example, each and/or all of the plurality of first filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. Thus, the circumferential offset may be formed as an integral segment, such as an arcuate segment, of a filament of the tubular body, wherein the arcuate segment of the filament forming the circumferential offset is located between first and second helically extending portions of the filament helically extending around the tubular body interwoven with other filaments of the tubular body. The circumferential offset may have first and second bases where the filament bends outward from the circumference of the tubular body with a radially outward projecting portion (e.g., an arcuate portion) of the circumferential offset extending therebetween. The circumferential offset may be oriented perpendicular to the longitudinal axis of the expandable framework such that the bases of the circumferential offset are longitudinally aligned at a common longitudinal position and at circumferentially spaced apart locations along the tubular body.

In addition or alternatively, in some embodiments, the second helical path of at least one of the plurality of second filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end <NUM> and the second end <NUM>. For example, at least one of the plurality of second filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. In some embodiments, the second helical path of multiple second filaments of the plurality of second filaments <NUM> may each include a circumferential offset along the body <NUM> between the first end <NUM> and the second end <NUM>. In some embodiments, the second helical path of each and/or all of the plurality of second filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end <NUM> and the second end <NUM>. For example, each and/or all of the plurality of second filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. Thus, the circumferential offset may be formed as an integral segment, such as an arcuate segment, of a filament of the tubular body, wherein the arcuate segment of the filament forming the circumferential offset is located between first and second helically extending portions of the filament helically extending around the expandable framework interwoven with other filaments of the tubular body. The circumferential offset may have first and second bases where the filament bends outward from the circumference of the tubular body with a radially outward projecting portion (e.g., an arcuate portion) of the circumferential offset extending therebetween. The circumferential offset may be oriented perpendicular to the longitudinal axis of the tubular body such that the bases of the circumferential offset are longitudinally aligned at a common longitudinal position and at circumferentially spaced apart locations along the tubular body.

In some embodiments, the at least one of the plurality of first filaments <NUM> (and/or the at least one of the plurality of second filaments <NUM>, where so configured) may include an anti-migration loop <NUM> protruding radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> at the circumferential offset. In some embodiments, the circumferential offset forms at least a portion of the anti-migration loop <NUM>. In some embodiments, the circumferential offset forms the anti-migration loop <NUM>. In some embodiments, each of the plurality of first filaments <NUM> (and/or the plurality of second filaments <NUM>) may include a circumferential offset and/or an anti-migration loop <NUM>. While the anti-migration loop(s) <NUM> is illustrated in <FIG> and <FIG> as being disposed at a center of the body <NUM> of the medical stent <NUM>, the anti-migration loop(s) <NUM> may be disposed at any location along the length of the body <NUM> of the medical stent <NUM>.

In some embodiments, a plurality of anti-migration loops <NUM> protruding radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> may form a circumferential row of anti-migration loops <NUM> extending around the body <NUM> of the medical stent <NUM>. In some embodiments, the plurality of anti-migration loops <NUM> within the circumferential row of anti-migration loops <NUM> may be axially and/or circumferentially aligned at a common axial location along the central longitudinal axis <NUM> of the medical stent <NUM>.

In some embodiments, at least a portion of the anti-migration loop <NUM> may be oriented substantially perpendicular to the central longitudinal axis <NUM> of the medical stent <NUM>. An anti-migration loop <NUM> that is oriented perpendicular to the central longitudinal axis <NUM> may render the medical stent <NUM> more resistant to axial migration in situ than an anti-migration loop that is oriented at an oblique angle to the central longitudinal axis <NUM>.

<FIG> illustrates aspects of a mandrel <NUM> for forming the medical stent <NUM>. The mandrel <NUM> includes a substantially cylindrical body and a plurality of protrusions <NUM> extending radially outward from the cylindrical body. In some embodiments, the plurality of protrusions <NUM> may be unitary with and/or monolithically formed with the cylindrical body. For example, the cylindrical body and the plurality of protrusions <NUM> may be formed from a single piece of material, such as by cutting, machining, etching, grinding, casting, injection molding, etc..

In some embodiments, the plurality of protrusions <NUM> may be generally diamond-shaped and/or pyramidal in form. For example, the plurality of protrusions <NUM> may taper from a wider base portion at the cylindrical body to a narrower top portion at an outermost radial extremity from a central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. In some embodiments, one or more of, or each of, the plurality of protrusions <NUM> may lack a "point" at its outermost radial extremity, thereby defining a somewhat flattened "top" of the protrusion. In some embodiments, the "top" of the protrusion may have a curved or arced surface associated with and/or defined by a radius of the mandrel <NUM> from the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body at the "top" of the protrusion. In some embodiments, the plurality of protrusions <NUM> may have a substantially uniform height and/or may extend to a substantially common radial extent relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. Other configurations are also contemplated.

The plurality of protrusions <NUM> defines a plurality of first channels <NUM> extending helically around the cylindrical body in a first direction from a first end of the mandrel <NUM> toward a second opposing end of the mandrel <NUM>. In some embodiments, the first direction may be clockwise. The plurality of protrusions <NUM> also defines a plurality of second channels <NUM> extending helically around the cylindrical body in a second direction opposite the first direction from the first end of the mandrel <NUM> toward the second opposing end of the mandrel <NUM>. In some embodiments, the second direction may be counterclockwise.

In at least some embodiments, the cylindrical body may form and/or define a base or bottom of the plurality of first channels <NUM> and/or the plurality of second channels <NUM>. For example, the cylindrical body may form a radially inwardmost extent of the plurality of first channels <NUM> and/or the plurality of second channels <NUM>, relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. In some embodiments, the plurality of protrusions <NUM> may define opposing sides of the plurality of first channels <NUM> and/or the plurality of second channels <NUM>. In some embodiments, the plurality of first channels <NUM> and/or the plurality of second channels <NUM> may open radially outward from the cylindrical body and/or relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. In some embodiments, the plurality of first channels <NUM> and/or the plurality of second channels <NUM> may be wider at a radially outward extent of the plurality of first channels <NUM> and/or the plurality of second channels <NUM> than at the base or bottom of the plurality of first channels <NUM> and/or the plurality of second channels <NUM>.

According to the invention, at least some of the plurality of protrusions <NUM> include a groove <NUM> formed therein (e.g., formed in the "top" of the protrusion) extending in a circumferential direction around the cylindrical body. The groove <NUM> may open radially outward from the protrusion, from the cylindrical body, and/or relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. According to the invention, the groove <NUM> is oriented substantially perpendicular to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. For example, a centerline of the groove <NUM> may be disposed within a plane that is oriented perpendicular to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. In some embodiments, the groove <NUM> may connect adjacent first channels of the plurality of first channels <NUM>. In some embodiments, the groove <NUM> may connect adjacent second channels of the plurality of second channels <NUM>. In some embodiments, the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein may form a circumferential row of protrusions extending around the cylindrical body. In some embodiments, the groove <NUM> of each protrusion of the circumferential row of protrusions having the groove <NUM> formed therein may be axially and/or circumferentially aligned at a common axial location along the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body.

In some embodiments, the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein may be raised protrusions <NUM> extending radially outward from the cylindrical body and/or relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body farther than a remainder of the plurality of protrusions <NUM>, as shown in <FIG> for example. While <FIG> illustrates the raised protrusions <NUM> having the groove <NUM>, and thus also forming the circumferential row of protrusions extending around the cylindrical body, the raised protrusions <NUM> are not explicitly necessary in every embodiment, and the mandrel <NUM> may be made without the raised protrusions <NUM>, instead using only the plurality of protrusions <NUM> as described herein, wherein at least some of the plurality of protrusions <NUM> include the groove <NUM>.

In some embodiments, the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein may form a plurality of circumferential rows of protrusions extending around the cylindrical body. In some embodiments, the groove <NUM> of each protrusion within one circumferential row of protrusions having the groove <NUM> formed therein may be axially and/or circumferentially aligned at a common axial location along the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body. The plurality of circumferential rows of protrusions may be longitudinally spaced apart from each other along the mandrel <NUM> and/or the cylindrical body.

<FIG> is a detailed view illustrating a portion of the medical stent <NUM> as described herein. The skilled artisan will recognize that in order to illustrate the relationship(s) between certain features, <FIG> is not shown in a straight on side view. Instead, a slight angle has been introduced to the view in order to allow the features to be seen and understood more easily. Additionally, one filament of the plurality of first filaments <NUM> is shown with hatching to make the filament and the first helical path stand out to the viewer and is not intended to denote a cross-section.

As discussed herein, the medical stent <NUM> includes the plurality of first filaments <NUM> and the plurality of second filaments <NUM>. At least one of the plurality of first filaments <NUM> includes a circumferential offset disposed between a first helically extending portion and a second helically extending portion. The circumferential offset forms the anti-migration loop <NUM>. According to the invention, the plurality of first filaments <NUM> is interwoven with the plurality of second filaments <NUM>, such as when forming a braid for example. <FIG> illustrates an over-under-over pattern of interwoven filaments. Other configurations and/or patterns are also contemplated.

In some embodiments, interweaving the plurality of first filaments <NUM> and the plurality of second filaments <NUM> defines a plurality of intersection points where the first filaments and the second filaments cross over and/or under each other. The first helical path of the at least one of the plurality of first filaments <NUM> may pass under a first one of the plurality of second filaments <NUM> at a first end <NUM> of the circumferential offset and/or the anti-migration loop <NUM> and may pass under a second one of the plurality of second filaments <NUM> at a second end <NUM> of the circumferential offset and/or the anti-migration loop <NUM>. In at least some embodiments, the second one of the plurality of second filaments <NUM> may be adjacent to the first one of the plurality of second filaments <NUM>. In this arrangement, the at least one of the plurality of first filaments <NUM> (e.g., the hatched filament in <FIG>) may pass under two adjacent filaments of the plurality of second filaments <NUM>. This is made possible by the circumferential offset and the formation of the anti-migration loop <NUM>, which extends radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> between two adjacent intersections of the plurality of first filaments <NUM> and the plurality of second filaments <NUM>.

In some embodiments, the medical stent <NUM> may be a covered stent. As such, the medical stent <NUM> may include a covering <NUM> disposed on and/or attached to the plurality of first filaments <NUM> and the plurality of second filaments <NUM>. The covering <NUM> may span interstices between adjacent filaments of the plurality of first filaments <NUM> and the plurality of second filaments <NUM>. In at least some embodiments, the covering <NUM> may be impervious to fluids, debris, and/or tissue ingrowth. In some embodiments, the covering <NUM> may extend along the body of the medical stent <NUM> from the first end to the second end. In some embodiments, the covering <NUM> may extend along an entire length of the medical stent <NUM>. In some embodiments, the covering <NUM> may be disposed on an inner surface of the body, the outer surface of the body, both the inner surface and the outer surface of the body, or the body may be embedded within the covering <NUM> with the anti-migration loop(s) <NUM> protruding radially outward from the covering <NUM>. Other configurations are also contemplated.

As discussed above, and shown in <FIG>, at least a portion of the anti-migration loop <NUM> is oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. In an alternative configuration, a portion of the anti-migration loop <NUM> is angled toward the second end <NUM>, as seen in <FIG>. In some embodiments, only a radially outer portion (a radially outer half or less than a radially outer half) of the anti-migration loop <NUM> may be angled toward the second end <NUM>, while a radially inner portion (a radially inner half or a remainder) of the anti-migration loop <NUM> may be oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. In another alternative configuration, a portion of the anti-migration loop <NUM> is angled toward the first end <NUM>, as seen in <FIG>. In some embodiments, only a radially outer portion (a radially outer half or less than a radially outer half) of the anti-migration loop <NUM> may be angled toward the first end <NUM>, while a radially inner portion (a radially inner half or a remainder) of the anti-migration loop <NUM> may be oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. Other configurations are also contemplated.

<FIG> and <FIG> illustrate schematically aspects of the first helical path and the second helical path used in forming the medical stent <NUM>. In order to make the paths and/or various elements clearer and easier to understand, some features are shown in bold or with a heavier line weight to differentiate from adjacent features. No difference in physical thickness (or other characteristics) of the features is intended or implied from this depiction.

As discussed above, the first helical path of at least one of the plurality of first filaments <NUM> includes a circumferential offset disposed along the body <NUM> between the first end <NUM> and the second end <NUM>. The circumferential offset forms the anti-migration loop <NUM>. The first helical path of the at least one of the plurality of first filaments <NUM> may pass under a first one of the plurality of second filaments <NUM> at a first end <NUM> of the circumferential offset and/or the anti-migration loop <NUM> and may pass under a second one of the plurality of second filaments <NUM> at a second end <NUM> of the circumferential offset and/or the anti-migration loop <NUM>. As may be seen in <FIG>, at least one of the plurality of first filaments <NUM> may include a first helically extending portion (shown angling down to the right toward the anti-migration loop <NUM>), a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion (shown angling down to the right away from the anti-migration loop <NUM>), and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion.

<FIG> illustrates aspects of a method of forming the medical stent <NUM> using the mandrel <NUM>. The method may include using the mandrel <NUM>, which comprises the cylindrical body and the plurality of protrusions <NUM> extending radially outward from the cylindrical body. The plurality of protrusions <NUM> defines a plurality of first channels <NUM> extending helically around the cylindrical body in a first direction and a plurality of second channels <NUM> extending helically around the cylindrical body in a second direction opposite the first direction. At least some of the plurality of protrusions <NUM> include the groove <NUM> formed therein extending in a circumferential direction around the cylindrical body.

The method includes winding the plurality of first filaments <NUM> around the mandrel <NUM> and/or the cylindrical body within the plurality of first channels <NUM> in the first direction and winding the plurality of second filaments <NUM> around the mandrel <NUM> and/or the cylindrical body within the plurality of second channels <NUM> in the second direction such that the plurality of first filaments <NUM> and the plurality of second filaments <NUM> are interwoven to define the body of the medical stent <NUM>.

The method includes at least some of the plurality of first filaments <NUM> are wound over the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein. Winding at least some of the plurality of first filaments <NUM> over the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein may form a plurality of anti-migration loops <NUM> extending radially outward from the body of the medical stent <NUM>, as seen in <FIG>. The groove <NUM> formed in the at least some of the plurality of protrusions <NUM> extends in a circumferential direction around the mandrel <NUM> and/or the cylindrical body and/or the central longitudinal axis thereof.

Winding at least some of the plurality of first filaments <NUM> over the plurality of protrusions <NUM> having the groove <NUM> formed therein will cause the first helical path of the at least some of the plurality of first filaments <NUM> to have a circumferential offset. Winding at least some of the plurality of first filaments <NUM> over the at least some of the plurality of protrusions <NUM> having the groove <NUM> formed therein within the groove <NUM> may shift those first filaments from one first channel to an adjacent first channel. Winding at least some of the plurality of first filaments <NUM> over the plurality of protrusions <NUM> having the groove <NUM> formed therein will also cause a circumferentially extending portion and/or the anti-migration loop <NUM> of the at least some of the plurality of first filaments <NUM> to extend radially outward from the body of the medical stent <NUM>, which is formed and/or defined by the plurality of first channels <NUM> and the plurality of second channels <NUM>. Each anti-migration loop <NUM> may extend radially outward from the body of the medical stent <NUM> between two adjacent second filaments of the plurality of second filaments <NUM>.

As discussed herein, in some embodiments, the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein may be raised protrusions <NUM> extending radially outward from the cylindrical body and/or relative to the central longitudinal axis of the mandrel <NUM> and/or the cylindrical body farther than a remainder of the plurality of protrusions <NUM>. Winding at least some of the plurality of first filaments <NUM> over the raised protrusions <NUM> will cause the circumferentially extending portion and/or the anti-migration loop <NUM> of the at least some of the plurality of first filaments <NUM> to extend radially outward from the body of the medical stent <NUM> even farther than winding at least some of the plurality of first filaments <NUM> over the plurality of protrusions <NUM> having the groove <NUM> formed therein.

As seen in <FIG>, each first filament of the at least some of the plurality of first filaments <NUM> wound over the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein extends under a first one of the plurality of second filaments <NUM> at and/or adjacent a first end of the groove <NUM> and under a second one of the plurality of second filaments <NUM> at and/or adjacent a second end of the groove <NUM>. The second one of the plurality of second filaments <NUM> may be adjacent to the first one of the plurality of second filaments <NUM>. Each first filament of the at least some of the plurality of first filaments <NUM> wound over the at least some of the plurality of protrusions <NUM> including the groove <NUM> formed therein extends under a first one of the plurality of second filaments <NUM> at and/or adjacent a first end <NUM> of the circumferential offset and/or the anti-migration loop <NUM> and under a second one of the plurality of second filaments <NUM> at and/or adjacent a second end <NUM> of the circumferential offset and/or the anti-migration loop <NUM>. In at least some embodiments, the first end <NUM> of the circumferential offset and/or the anti-migration loop <NUM> may be disposed within the first end of the groove <NUM> and the second end <NUM> of the circumferential offset and/or the anti-migration loop <NUM> may be disposed within the second end of the groove <NUM>.

<FIG> schematically illustrates aspects of an alternative medical stent <NUM> according the instant disclosure. The medical stent <NUM> may be formed in the same way and/or may include the same or similar features as the medical stent <NUM>. Similar features may be identified using like reference numerals. The medical stent <NUM> has a first end, a second end, and a central longitudinal axis <NUM> extending from the first end to the second end. The medical stent <NUM> may include a body <NUM> defining an outer surface <NUM>. In some embodiments, the body <NUM> may extend from the first end to the second end. Other configurations described herein with respect to the medical stent <NUM> are also contemplated.

The medical stent <NUM> includes a plurality of first filaments <NUM> each extending in a first helical path around the central longitudinal axis <NUM> in a first direction from the first end toward and/or to the second end. In some embodiments, the first direction may be clockwise. The medical stent <NUM> includes a plurality of second filaments <NUM> each extending in a second helical path around the central longitudinal axis <NUM> in a second direction from the first end toward and/or to the second end. In some embodiments, the second direction may be opposite the first direction. In some embodiments, the second direction may be counterclockwise.

In some embodiments, the first helical path of at least one of the plurality of first filaments <NUM> includes a circumferential offset disposed along the body <NUM> between the first end and the second end. For example, at least one of the plurality of first filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion.

In some embodiments, the first helical path of multiple first filaments of the plurality of first filaments <NUM> may each include a circumferential offset along the body <NUM> between the first end and the second end. In some embodiments, the first helical path of each and/or all of the plurality of first filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end and the second end. For example, each and/or all of the plurality of first filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. In some embodiments, the first helical path of the at least one of the plurality of first filaments <NUM> includes a plurality of circumferential offsets longitudinally spaced apart from each other between the first end and the second end.

In addition or alternatively, in some embodiments, the second helical path of at least one of the plurality of second filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end and the second end. For example, at least one of the plurality of second filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. In some embodiments, the second helical path of multiple second filaments of the plurality of second filaments <NUM> may each include a circumferential offset along the body <NUM> between the first end and the second end. In some embodiments, the second helical path of each and/or all of the plurality of second filaments <NUM> may include a circumferential offset disposed along the body <NUM> between the first end and the second end. For example, each and/or all of the plurality of second filaments <NUM> may include a first helically extending portion, a second helically extending portion circumferentially offset from and substantially parallel to the first helically extending portion, and a circumferentially extending portion disposed between the first helically extending portion and the second helically extending portion. In some embodiments, the second helical path of the at least one of the plurality of second filaments <NUM> includes a plurality of circumferential offsets longitudinally spaced apart from each other between the first end and the second end.

In some embodiments, the at least one of the plurality of first filaments <NUM> (and/or the at least one of the plurality of second filaments <NUM>, where so configured) includes an anti-migration loop <NUM> protruding radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> at the circumferential offset. In some embodiments, the circumferential offset forms at least a portion of the anti-migration loop <NUM>. In some embodiments, the circumferential offset forms the anti-migration loop <NUM>. In some embodiments, each of the plurality of first filaments <NUM> (and/or the plurality of second filaments <NUM>) may include a circumferential offset and/or an anti-migration loop <NUM>. In some embodiments, the at least one of the plurality of first filaments <NUM> (and/or the at least one of the plurality of second filaments <NUM>, where so configured) may include a plurality of anti-migration loops <NUM> protruding radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> at the plurality of circumferential offsets.

In some embodiments, the plurality of anti-migration loops <NUM> protruding radially outward from the outer surface <NUM> of the body <NUM> of the medical stent <NUM> may form a plurality of circumferential rows of anti-migration loops <NUM> extending around the body <NUM> of the medical stent <NUM>. In some embodiments, the anti-migration loops <NUM> within one circumferential row of anti-migration loops <NUM> may be axially and/or circumferentially aligned at a common axial location along the central longitudinal axis <NUM> of the medical stent <NUM>. The plurality of circumferential rows of anti-migration loops <NUM> may be longitudinally spaced apart from each other along the body <NUM> of the medical stent <NUM>.

In some embodiments, interweaving the plurality of first filaments <NUM> and the plurality of second filaments <NUM> defines a plurality of intersection points where the first filaments and the second filaments cross over and/or under each other. The first helical path of the at least one of the plurality of first filaments <NUM> may pass under a first one of the plurality of second filaments <NUM> at a first end of the circumferential offset and/or the anti-migration loop <NUM> and may pass under a second one of the plurality of second filaments <NUM> at a second end of the circumferential offset and/or the anti-migration loop <NUM>. In at least some embodiments, the second one of the plurality of second filaments <NUM> may be adjacent to the first one of the plurality of second filaments <NUM>. In this arrangement, the at least one of the plurality of first filaments <NUM> (e.g., the hatched filament in <FIG>) may pass under two adjacent filaments of the plurality of second filaments <NUM>. This is made possible by the circumferential offset and the formation of the anti-migration loop <NUM>, which extends radially outward from the outer surface of the body of the medical stent <NUM> between two adjacent intersections of the plurality of first filaments <NUM> and the plurality of second filaments <NUM>.

In some embodiments, the first helical path of the at least one of the plurality of first filaments <NUM> includes a plurality of circumferential offsets longitudinally spaced apart from each other between the first end and the second end. In some embodiments, the at least one of the plurality of first filaments <NUM> may include a plurality of anti-migration loops <NUM> protruding radially outward from the outer surface of the body of the medical stent <NUM> at the plurality of circumferential offsets. For example, each circumferential offset may form an anti-migration loop <NUM>, and there may be a plurality of anti-migration loops <NUM> formed from and/or within a single first filament of the plurality of first filaments <NUM>, as shown in <FIG>.

In some embodiments, the plurality of anti-migration loops <NUM> protruding radially outward from the outer surface of the body of the medical stent <NUM> may form a plurality of circumferential rows of anti-migration loops <NUM> extending around the body of the medical stent <NUM>. In some embodiments, the anti-migration loops <NUM> within one circumferential row of anti-migration loops <NUM> may be axially and/or circumferentially aligned at a common axial location along the central longitudinal axis of the medical stent <NUM>. The plurality of circumferential rows of anti-migration loops <NUM> may be longitudinally spaced apart from each other along the body of the medical stent <NUM>.

As discussed above, and shown in <FIG>, at least a portion of the anti-migration loop <NUM> is oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. In an alternative configuration, a portion of the anti-migration loop <NUM> is angled toward the second end. In some embodiments, only a radially outer portion (a radially outer half or less than a radially outer half) of the anti-migration loop <NUM> may be angled toward the second end, while a radially inner portion (a radially inner half or a remainder) of the anti-migration loop <NUM> may be oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. In another alternative configuration, a portion of the anti-migration loop <NUM> is angled toward the first end. In some embodiments, only a radially outer portion (a radially outer half or less than a radially outer half) of the anti-migration loop <NUM> may be angled toward the first end, while a radially inner portion (a radially inner half or a remainder) of the anti-migration loop <NUM> may be oriented substantially perpendicular to the central longitudinal axis of the medical stent <NUM>. Other configurations are also contemplated.

The materials that can be used for the various components of the medical stent(s), the mandrel, and the various elements thereof disclosed herein may include those commonly associated with medical devices and mandrels. For simplicity purposes, the following discussion refers to the apparatus. However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other elements, members, components, or devices disclosed herein, such as, but not limited to, the medical stent, the mandrel, the filaments, the anti-migration loops, the covering, and/or elements or components thereof.

In some embodiments, the apparatus, and/or components thereof, may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material.

Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), MARLEX® high-density polyethylene, MARLEX® low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-<NUM> (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, polyurethane silicone copolymers (for example, ElastEon® from Aortech Biomaterials or ChronoSil® from AdvanSource Biomaterials), biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments the sheath can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about <NUM> percent LCP.

Some examples of suitable metals and metal alloys include stainless steel, such as 304V, <NUM>, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® <NUM>, UNS: N06022 such as HASTELLOY® C-<NUM>®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® <NUM>, NICKELVAC® <NUM>, NICORROS® <NUM>, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; platinum; palladium; gold; combinations thereof; or any other suitable material.

In at least some embodiments, portions or all of the apparatus, and/or components thereof, may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of the apparatus in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the apparatus to achieve the same result.

In some embodiments, a degree of Magnetic Resonance Imaging (MRI) compatibility is imparted into the apparatus and/or other elements disclosed herein. For example, the apparatus, and/or components or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (e.g., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. The apparatus, or portions thereof, may also be made from a material that the MRI machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, and the like, and others.

Claim 1:
A medical stent (<NUM>, <NUM>) having a first end (<NUM>), a second end (<NUM>), and a central longitudinal axis (<NUM>, <NUM>) extending from the first end to the second end, comprising:
a plurality of first filaments (<NUM>, <NUM>) each extending in a first helical path around the central longitudinal axis in a first direction; and
a plurality of second filaments (<NUM>, <NUM>) each extending in a second helical path around the central longitudinal axis in a second direction;
wherein the plurality of first filaments (<NUM>, <NUM>) is interwoven with the plurality of second filaments (<NUM>, <NUM>);
wherein the first helical path of at least one of the plurality of first filaments (<NUM>, <NUM>) includes a circumferential offset disposed between the first end (<NUM>) and the second end (<NUM>),
wherein the at least one of the plurality of first filaments (<NUM>, <NUM>) includes an anti-migration loop (<NUM>, <NUM>) protruding radially outward from an outer surface (<NUM>, <NUM>) of the medical stent at the circumferential offset,
wherein the circumferential offset forms the anti-migration loop (<NUM>, <NUM>), at least a portion of the anti-migration loop (<NUM>, <NUM>) being oriented substantially perpendicular to the central longitudinal axis (<NUM>, <NUM>), and a portion of the anti-migration loop (<NUM>, <NUM>) being angled toward the first end or the second end of the medical stent.