Patent Description:
The present disclosure pertains to medical devices, methods for manufacturing medical devices. More particularly, the present disclosure pertains to stents including a valve, such as an anti-reflux valve, and methods for manufacturing.

The lower esophageal sphincter is a muscle located between the esophagus and the stomach. The sphincter normally functions as a one-way valve, allowing material (e.g., food) that travels downward through the esophagus to enter the stomach while preventing the backflow (reflux) of hydrochloric acid and other gastric contents into the esophagus. However, in some cases the lower esophageal sphincter does not close adequately, and therefore, permits stomach acid to reflux into the esophagus, causing heartburn. A weak or inoperable lower esophageal sphincter is a major cause of gastroesophageal reflux disease (GERD).

Therefore, a variety of intracorporeal medical devices have been developed to treat gastroesophageal disease caused by a malfunctioning lower esophageal sphincter. For example, elongated stents incorporating flexible valves have been developed to allow material (e.g., food) to travel through the esophagus and enter the stomach while also preventing stomach acid to reflux into the esophagus. However, there is an ongoing need to provide alternative configurations of and/or methods of forming stents including a two-way valve to treat gastroesophageal disease, as well as other medical conditions.

<CIT> relates to a medical stent having a valve and a method of manufacture. The stent includes a self-expanding tubular body having a proximal end portion and a distal end portion. The tubular body is formed by braiding or knitting a plurality of flexible wires. The valve is basket-shaped and formed integral to the stent to prevent undesirable backflow across the valve. The valve is formed by converting braided wires of the stent, by providing elastomeric material onto a mold or fixture to form an elastomeric valve. The valve is normally closed but configured to allow easy opening in response to a predetermined condition.

<CIT> relates to a one-way valve suitable for implant in the human vascular system. The valve is formed by a tube of braided filaments and has an upstream end supported in an open configuration by a radial support. The valve has a downstream end formed by a plurality of flexible leaflets resiliently biased into a closed configuration sealing the valve. The leaflets separate under pressure to allow fluid flow downstream but close in response to back pressure to prevent retrograde flow. The leaflets are biased by internal elastic forces within the filaments or by means of a resilient flexible membrane.

<CIT> relates to a stent including strut members which may be wires or filaments interwoven to form the stent structure. The stent includes an outer layer and an inner layer. A valve member is positioned within the lumen of the stent and defined as a portion of the inner layer. The inner layer separates from the inner surface of the stent member at a first detachment point and a second detachment point radially inward to form the valve. A chamber is defined as the space between the valve wall and the stent member between the detachment points.

This disclosure provides design, material, manufacturing method for medical devices. An example medical device includes an expandable stent. The stent includes a tubular scaffold formed of one or more interwoven filament. The tubular scaffold includes an inner surface and a flexible valve extending radially inward from the inner surface of the scaffold. Further, the valve is configured to shift between a closed configuration and an open configuration and the one or more filaments of the scaffold bias the valve to the closed configuration while in a nominally deployed state.

Alternatively or additionally to any of the embodiments above, wherein the valve shifts from the closed configuration to the open configuration due to a peristaltic force applied to the tubular scaffold.

Alternatively or additionally to any of the embodiments above, wherein the valve includes a valve opening extending therethrough, and wherein the valve opening is ovular-shaped in the open configuration.

According to the invention, the tubular scaffold includes a first tapered region and a second tapered region, and wherein the valve is positioned between the first tapered region and the second tapered region.

Alternatively or additionally to any of the embodiments above, wherein the first tapered region is configured to funnel material toward the valve.

Alternatively or additionally to any of the embodiments above, wherein the one or more filaments of the scaffold are configured to radially expand to shift the valve from the closed configuration to the open configuration when subjected to a radial expansion force of <NUM> N/cm<NUM> or greater.

Alternatively or additionally to any of the embodiments above, further comprising a coating disposed along the one or more filaments, and wherein the valve is formed from a portion of the coating.

Alternatively or additionally to any of the embodiments above, the valve is a two-way valve configured to permit material to pass through the valve in a first direction and a second direction, and wherein the first direction is opposite the second direction.

An example method of manufacturing a stent includes forming a tubular scaffold, wherein the tubular scaffold includes a first end, a second end and a narrowed region positioned between the first end and the second end. The tubular scaffold is positioned on a coating mandrel such that the coating mandrel radially expands the narrowed region such that the tubular scaffold is spaced away from the coating mandrel at the narrowed region. A coating is applied to the tubular scaffold while the tubular scaffold is positioned on the coating mandrel. Applying the coating to the tubular scaffold includes forming a valve within the narrowed region of the tubular scaffold. Thereafter, the tubular scaffold is removed from the coating mandrel and the tubular scaffold radially collapses at the narrowed region to bias the valve in a closed configuration after being removed from the coating mandrel.

Alternatively or additionally to any of the embodiments above, wherein forming the tubular scaffold comprises braiding at least two or more stent filaments together.

Alternatively or additionally to any of the embodiments above, wherein forming the tubular scaffold further comprises positioning the tubular scaffold on a shaping mandrel, and wherein the shaping mandrel is configured to radially pinch the one or more filaments to create the narrowed region.

Alternatively or additionally to any of the embodiments above, wherein forming the tubular scaffold further comprises heat treating the tubular scaffold while the tubular scaffold is positioned on the shaping mandrel.

Alternatively or additionally to any of the embodiments above, wherein applying the coating to the tubular scaffold further includes spraying the coating on the tubular scaffold.

Alternatively or additionally to any of the embodiments above, wherein the valve has an ovular-shaped opening in an open configuration.

Another example expandable stent includes a braided tubular scaffold formed of a plurality of interwoven filaments. The tubular scaffold includes a first end, a second end and a lumen extending therethrough. The tubular scaffold further includes a narrowed region positioned between the first end and the second end. A flexible valve is positioned within the lumen at the narrowed region. The plurality of interwoven filaments apply a radially compressive force on the valve to bias the valve to a closed configuration while the stent is in a nominally deployed state.

Alternatively or additionally to any of the embodiments above, wherein the radially compressive force is less than or equal to <NUM> N/cm<NUM>.

Alternatively or additionally to any of the embodiments above, wherein the narrowed region includes a first diameter while in the nominally deployed state, and wherein the narrowed region is configured to radially expand to open the valve when subjected to a radially expanding force of <NUM> N/cm<NUM> or greater.

Alternatively or additionally to any of the embodiments above, wherein the valve shifts from the closed configuration to an open configuration due to a peristaltic force applied to the plurality of interwoven filaments.

Alternatively or additionally to any of the embodiments above, further comprising a coating disposed along the plurality of filaments, and wherein the valve is formed from a portion of the coating.

The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure.

Gastroesophageal reflux disease (GERD) is a medical condition whereby stomach acids enter the lower portion of the esophagus because the lower esophageal sphincter (positioned at the entrance of the stomach) fails to close properly. In some instances, the lower esophageal sphincter's inability to close is due to disease or general atrophy. When left open, the sphincter may permit reflux of stomach acids into the esophagus, causing severe heartburn and potentially contributing to the onset of other diseases.

One method of treating GERD is to place an anti-reflux stent into the entrance of the stomach. An anti-reflux stent may include an expandable two-way valve which allows food and liquid to enter the stomach but limits liquids (stomach acids) from passing back through the valve under normal digestive conditions (e.g., the valve may permit liquids to pass back through the valve during periods then the stomach contracts to permit vomiting). In general, there is an ongoing need for an anti-reflux stent to provide a smooth lumen opening into the stomach while limiting stomach acids from passing back through the valve and into the esophagus.

<FIG> shows an example stent <NUM>. Stent <NUM> may include a tubular scaffold <NUM> having a first end, which may extend to the first end of the stent <NUM>, a second end, which may extend to the second end of the stent <NUM>, and a lumen extending therethrough. The tubular scaffold <NUM> may be configured to provide the support structure for stent <NUM>. The tubular scaffold <NUM> may be formed of one or more stent filaments <NUM>, or a plurality of stent filaments <NUM>. Filaments <NUM> may extend longitudinally along stent <NUM>. In some instances, filaments <NUM> may extend longitudinally along stent <NUM> in a helical fashion. While <FIG> shows filaments <NUM> extending along the entire length of stent <NUM> between first and second ends of stent <NUM>, in other examples, the filaments <NUM> may extend only along a portion of the length of stent <NUM>.

Additionally, <FIG> shows example stent <NUM> including one or more enlarged portions (e.g., flanges) <NUM> proximate the first end <NUM> and second end <NUM> of the stent <NUM>. In some instances, enlarged portions <NUM> may be defined as an increase in the outer diameter, the inner diameter or both the inner and outer diameter of stent <NUM> relative to a medial region of the stent <NUM>. The enlarged portions <NUM> may be beneficial to anchor the stent within the esophagus and/or the opening to the stomach. Additionally, as will be described in greater detail below, <FIG> illustrates stent <NUM> including a first tapered portion <NUM>, a second tapered portion <NUM> and a narrowed region <NUM> positioned between the first tapered portion <NUM> and the second tapered portion <NUM>. First tapered portion <NUM> may taper toward the narrowed region (i.e., neck) <NUM> from a larger diameter to a smaller diameter, while second tapered portion <NUM> may taper toward the narrowed region (i.e., neck) <NUM> from a larger diameter to a smaller diameter.

In some instances, stent <NUM> may be a self-expanding stent. Self-expanding stent examples may include stents having one or more interwoven filaments <NUM> to form a tubular scaffold <NUM>, having openings defined between adjacent filaments <NUM>. For example, stent filaments <NUM> may be wires braided, knitted or otherwise interwoven to form the tubular scaffold <NUM>. Openings or interstices through the wall of the tubular scaffold <NUM> may be defined between adjacent stent filaments <NUM>. Alternatively, tubular scaffold <NUM> of stent <NUM> may be a monolithic structure formed from a cylindrical tubular member, such as a single, cylindrical tubular laser-cut Nitinol tubular member, in which the remaining portions of the tubular member form the stent filaments <NUM> with openings defined therebetween.

Stent <NUM>, or components thereof, (including tubular scaffold <NUM> and/or stent filaments <NUM>) disclosed herein may be constructed from a variety of materials. For example, stent <NUM> (e.g., self-expanding or balloon expandable), or components thereof, may be constructed from a metal (e.g., Nitinol). In other instances, stent <NUM> or components thereof may be constructed from a polymeric material (e.g., PET). In yet other instances, stent <NUM>, or components thereof, may be constructed from a combination of metallic and polymeric materials. Additionally, stent <NUM>, or components thereof, may include a bioabsorbable and/or biodegradable material.

Additionally, stent <NUM> may include one or more coating layers disposed on tubular scaffold <NUM>, such as positioned on and/or adjacent to the inner surface and/or outer surface thereof. The coating layer may be positioned on a portion of filaments <NUM> forming tubular scaffold <NUM> and extend across openings or cells between adjacent filaments <NUM>. For example, <FIG> shows stent <NUM> including a coating layer <NUM> disposed along the inner surface of tubular scaffold <NUM>. In some instances, coating layer <NUM> may be an elastomeric or non-elastomeric material. For example, coating layer <NUM> may be a polymeric material, such as silicone, polyurethane, or the like. Further, the coating layer <NUM> may span the spaces (e.g., openings, cells, interstices) in the wall of tubular scaffold <NUM> defined between adjacent filaments <NUM>. For example, the coating layer <NUM> may extend along and cover the inner surface and/or outer surface of tubular scaffold <NUM> such that the coating layer <NUM> spans one or more of spaces (e.g., openings, cells, interstices) between filaments <NUM> in the wall of tubular scaffold <NUM>.

As described above, stent <NUM> may have a first end <NUM> and a second end <NUM>. When positioned in a body lumen (e.g., esophagus) first end <NUM> may be defined as the proximal end of stent <NUM> and oriented as the end of stent <NUM> closest to a patient's mouth and second end <NUM> may be defined as the distal end of stent <NUM> and oriented as the end of stent <NUM> closest to a patient's stomach. In some examples, a first end region of stent <NUM> extending proximal of a proximal most flange <NUM> may be longer than a second end region of stent <NUM> extending distal of a distal most flange <NUM>. The additional length of first end region may extend into and cover the lower esophagus in the event a small amount of stomach acid were to leak through the valve <NUM> (shown in <FIG>).

As shown in <FIG>, coating layer <NUM> may extend along the length of tubular scaffold <NUM> from first end <NUM> to second end <NUM>. In other words, in some instances coating layer <NUM> may be defined as a continuous layer that extends from first end <NUM> to second end <NUM> of stent <NUM> and fully extends across and fills cells or interstices defined between filaments <NUM> of tubular scaffold <NUM>. However, in other instances coating layer <NUM> may extend less than the entire length of stent <NUM>, if desired, leaving a portion of cells or interstices defined between filaments <NUM> of tubular scaffold <NUM> unfilled or open.

Additionally, <FIG> shows a valve <NUM> positioned within the lumen of stent <NUM>. As will be discussed in greater detail below, valve <NUM> may be formed as a portion of coating layer <NUM>. In other words, valve <NUM> may be a unitary or monolithic structure formed in conjunction with forming coating layer <NUM> on tubular scaffold <NUM>. For example, <FIG> illustrates that valve <NUM> may be an inwardly extending portion of coating layer <NUM> extending radially inward of tubular scaffold <NUM> at narrowed or necked region <NUM>. In other words, valve <NUM> may be defined as a unitary or monolithic portion of coating layer <NUM> that extends radially inward from an inner surface of tubular scaffold <NUM> toward the central longitudinal axis <NUM> of stent <NUM>.

Further, in some examples, valve <NUM> may be defined as a monolithic portion of coating layer <NUM> that extends circumferentially within the lumen of stent member <NUM>. In other words, it can be appreciated that valve <NUM> may be defined as an annular member that extends continuously around the lumen of stent <NUM> positioned radially inward of tubular scaffold <NUM> in the narrowed or necked region <NUM>. Further, valve <NUM> may be defined as an uninterrupted extension of coating layer <NUM> projecting toward central longitudinal axis <NUM>, forming an annular rim of polymeric material radially inward of tubular scaffold <NUM> in the narrowed or necked region <NUM>.

As described above, <FIG> illustrates that stent <NUM> may include a first tapered (e.g., conical) region <NUM> and a second tapered (e.g., conical) region <NUM> with the narrowed or necked region <NUM> positioned therebetween. Both first conical region <NUM> and second conical region <NUM> may generally be shaped to taper radially inwardly in opposite directions toward the longitudinal axis <NUM> providing the stent <NUM> with an hourglass shape. For example, first conical region <NUM> may taper radially inward from a first transition point <NUM> along stent <NUM> to valve <NUM> while second conical region <NUM> may taper radially outward from valve <NUM> to a second transition point <NUM> along stent <NUM>. For example, the first conical region <NUM> (including the stent filaments <NUM> and coating layer <NUM>) may bear some resemblance to a cone-shaped funnel tapering from a wide portion nearest a patient's mouth to valve <NUM>. Further, second conical region <NUM> (including the stent filaments <NUM> and coating layer <NUM>) may bear some resemblance to a cone-shaped funnel tapering from valve <NUM> to a wide portion closer to a patient's stomach. Further, as illustrated in <FIG>, in a closed configuration, valve <NUM> may taper inwardly toward central longitudinal axis <NUM> and close (e.g., contact, seal, etc.) onto itself such that it stops flow of material (e.g., stomach acid) from flowing through the lumen of stent <NUM>. As discussed above, it may be desirable for valve <NUM> to prevent stomach acids from flowing from a patient's stomach toward the patient's mouth. <FIG> shows valve <NUM> in a closed configuration. The stent <NUM> may be configured to bias valve <NUM> to the closed configuration in a nominally deployed state.

As described above, in some instances it may be desirable for valve <NUM> to expand radially outward to permit nutritional material (e.g., food, water, etc.) to pass through the lumen of stent <NUM>. For example, in some examples it is desirable for valve <NUM> to radially expand to permit a bolus of food or liquid to pass from a patient's mouth, through the valve <NUM>, to the stomach. As will be described in greater detail below, at least some stent and valve examples disclosed herein may include stent filaments of tubular scaffold <NUM> which impart a radially compressive force inward on valve <NUM> to maintain the valve <NUM> in a closed configured while in a "nominally-deployed" state (e.g., a state in which no outside forces are acting on the stent <NUM> to move the valve <NUM> to an open configuration).

Further, the compressive force exerted by filaments <NUM> of tubular scaffold <NUM> on valve <NUM> must be low enough such that normal, peristaltic contractions associated with normal digestive processing (e.g., normal eating and digesting of food) will open valve <NUM>, thereby permitting the bolus of nutritional material to pass through valve <NUM> and into the stomach (while also permit vomiting contractions to expel food back through valve <NUM>). However, this compressive force must also be large enough to ensure the valve <NUM> reverts to the closed configuration when in the nominally deployed state such that stomach acids will not leak through the valve <NUM> from the stomach, causing symptoms of acid reflux.

Therefore, in at least some examples a threshold radially inward compressive force may be imparted by the filaments <NUM> onto the valve <NUM> in the nominally deployed state to hold the valve <NUM> in the closed configuration. In other words, stent <NUM> (including the radial compression of filaments <NUM>) must be designed such that valve <NUM> remains closed in a nominally deployed state, yet opens when peristatic forces greater than the threshold inward compressive force are imparted onto the valve <NUM> (e.g., when peristaltic forces push a bolus of food or liquid through the valve aperture <NUM>, thereby causing radially outward expansion forces of greater than the threshold inward compressive force to be imparted to the scaffold <NUM>) to overcome the radially inwardly compressive forces biasing the valve <NUM> to the closed configuration. In some instances, the threshold inward compressive force may be less than <NUM> N/cm<NUM>, less than <NUM> N/cm<NUM>, less than <NUM> N/cm<NUM>, less than <NUM> N/cm<NUM>, less than <NUM> N/cm<NUM>, or less than <NUM> N/cm<NUM>. Furthermore, forces less than the threshold inward compressive force (such as those imparted onto the valve <NUM> via acid reflux) will not cause valve <NUM> to open, thereby preventing stomach acids from flowing from the stomach into the esophagus. In some instances, the threshold inward compressive force may be at least <NUM> N/cm<NUM>, at least <NUM> N/cm<NUM>, at least <NUM> N/cm<NUM>, at least <NUM> N/cm<NUM>, at least <NUM> N/cm<NUM>, at least <NUM> N/cm<NUM>, or at least <NUM> N/cm<NUM>. In some instances, the threshold inward compressive force may be in the range of between <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, in the range of between <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, in the range of between <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, in the range of between <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, in the range of between <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, in the range of <NUM> N/cm<NUM> to <NUM> N/cm<NUM>, for example.

<FIG> and <FIG> illustrate valve <NUM> expanding radially outward to allow a bolus of nutritional material (e.g., food) <NUM> to pass through the lumen of stent <NUM> and through valve <NUM>. As shown by the arrow in <FIG>, and, in general, bolus of nutritional material <NUM> may flow through stent <NUM> from a first end <NUM> (e.g., the end closest to a patient's mouth) to a second end <NUM> (e.g., the end closest to a patient's stomach). <FIG> illustrates that valve <NUM> may permit the material <NUM> to pass through the lumen of the stent <NUM> by expanding radially outward as the material <NUM> passes through valve <NUM>. While not shown in <FIG>, it is contemplated that in some examples valve <NUM> may conform to the shape of material <NUM> as it passes through valve <NUM>.

<FIG> illustrates an enlarged and detailed view of example stent <NUM> including tubular scaffold <NUM> and valve <NUM>. As described above, stent <NUM> may include a coating layer <NUM> covering tubular scaffold <NUM> and forming valve <NUM>. For example, <FIG> illustrates that coating layer <NUM> may include a thickness depicted as "X" extending along a substantial portion and covering filaments <NUM>, such as covering an inner surface and/or outer surface of filaments <NUM>. For illustrative purposes, coating layer <NUM> is shown extending along inner surface of tubular scaffold <NUM>, however, it is noted that additionally or alternatively coating layer <NUM> may extend along outer surface of tubular scaffold in some embodiments. In some examples, the coating layer <NUM> may be formed from a silicone material or a polyurethane material, for instance.

Further, as shown in <FIG> (and illustrated further in <FIG>), the coating layer <NUM> may extend radially inward from the inner surface of tubular scaffold <NUM> to form the valve <NUM> at narrowed or necked region <NUM> of stent <NUM>. As will be further illustrated in <FIG>, valve <NUM> may have an annular shape and include a circumferential, curvilinear surface extending around the longitudinal axis <NUM> of stent <NUM> whereby the coating layer <NUM> extends away from the inner surface of the wall of the tubular scaffold <NUM> (e.g., radially inward toward the longitudinal axis <NUM>) to form valve <NUM>. As illustrated in <FIG>, valve <NUM> may include a thickness depicted as "Y" in <FIG>.

<FIG> illustrates that in some instances the thickness "Y" of valve <NUM> may be substantially equal to the thickness "X" of coating layer <NUM>. In other words, coating layer <NUM> may maintain a substantially uniform thickness "X" along the length of scaffold <NUM> which extends uniformly to form the thickness "Y" of valve <NUM>. However, in other embodiments the wall thickness "X" of coating layer <NUM> and/or the thickness "Y" defining valve <NUM> may be different. For example, some portions of coating layer <NUM> and/or the thickness defining valve <NUM> may be thinner or thicker than other portions along stent <NUM>.

Similar to that shown in <FIG>, <FIG> illustrates the first tapered region <NUM> and the second tapered region <NUM>, both of which may bear some resemblance to a cone-shaped funnel and together form an hourglass shape. For example, stent <NUM> (including tubular scaffold <NUM> and coating layer <NUM>) may taper radially inward from a first transition point <NUM> toward valve <NUM>. Valve <NUM> includes a valve aperture <NUM>. Valve aperture <NUM> may be defined as the "opening" of valve <NUM> (e.g., the opening of valve <NUM> through which nutritional material may flow). As illustrated in <FIG>, valve aperture <NUM> may be aligned with the central longitudinal axis <NUM>.

<FIG> further illustrates stent <NUM> (including scaffold <NUM> and coating layer <NUM>) tapering radially inward from a second transition point <NUM> toward valve <NUM>. Further, both the first tapered region <NUM> and the second tapered region <NUM> may include a wide portion having an inner diameter (depicted in <FIG> as dimension "W") tapering to a narrower portion having an inner diameter (depicted in <FIG> as dimension "Z") less than the inner diameter of the wide portion. As shown in <FIG>, the wide portion of each of the first tapered region <NUM> and the second tapered region <NUM> may be positioned adjacent to first transition point <NUM> and second transition point <NUM>, respectively. Further, the narrower portion may be positioned closer to valve <NUM>.

<FIG> shows a cross-sectional view of stent <NUM> through narrowed region <NUM> and valve <NUM> taken along line <NUM>-<NUM> of <FIG>. In particular, line <NUM>-<NUM> of <FIG> intersects valve aperture <NUM> of valve <NUM> described above. As shown in <FIG>, valve aperture <NUM> may intersect the longitudinal axis <NUM> of stent <NUM>. As described above, <FIG> depicts valve <NUM> in a closed configuration whereby filaments <NUM> (defining scaffold <NUM> described above) are imparting a radial inward compressive force onto valve <NUM>, thereby maintaining valve aperture <NUM> in a closed configuration. <FIG> illustrates that narrowed region <NUM> of stent <NUM> may include an outer diameter which is depicted as "Dc" in <FIG> in the closed configuration. The closed configuration of valve <NUM> may be defined as a configuration which the valve aperture <NUM> is closed and prevents material from flowing through the valve aperture <NUM>. As described above, <FIG> shows the shape of valve <NUM> as substantially circular and extending circumferentially around the longitudinal axis <NUM> of the stent <NUM>.

<FIG> shows an enlarged view of stent <NUM> described above with valve <NUM> in an open configuration. For example, <FIG> shows valve aperture <NUM> opened to a width depicted as dimension "V" in <FIG>. As discussed above, it can be appreciated that valve aperture <NUM> may open via a force being imparted radially outward (e.g., a force generated via nutritional material being driven through the valve <NUM> via peristalsis) which is large enough to overcome the radially inward compressive force (described above) imparted by filaments <NUM> of tubular scaffold <NUM> described above.

<FIG> shows a cross-sectional view of the stent <NUM> through narrowed region <NUM> and valve <NUM> taken along line <NUM>-<NUM> of <FIG>. <FIG> further illustrates the valve <NUM> in an open configuration. In other words, <FIG> shows narrowed region <NUM> of stent <NUM> being expanded to an outer diameter depicted as "Do" in <FIG>. Diameter Do may be greater than diameter Dc described above with respect to <FIG>. It can be appreciated that as narrowed region <NUM> of stent <NUM> expands due to peristaltic forces acting thereupon, the outer diameter of narrowed region of stent <NUM> may increase from diameter Dc depicted in <FIG> to diameter Do depicted in <FIG>. Accordingly, as the outer diameter of narrowed region of stent <NUM> increases from diameter Dc depicted in <FIG> to diameter Do depicted in <FIG>, valve <NUM> (including valve aperture <NUM>) may shift from a closed configuration to an open configuration. Likewise, tubular scaffold <NUM> radially expands in narrowed region <NUM> between the closed configuration to the opened configuration.

Additionally, line <NUM>-<NUM> of <FIG> transects the valve aperture <NUM> described above. <FIG> illustrates the valve <NUM> extending radially inward from stent filaments <NUM> (defining scaffold <NUM> described above). As shown in <FIG>, valve aperture <NUM> may be an opening centered about the central longitudinal axis <NUM> of the lumen of stent <NUM>. However, while the figures described herein depict example valves and related elements centered about the central longitudinal axis <NUM>, it is contemplated that any of the examples described herein may be designed such that the structural elements defining any portion of stent <NUM> and/or valve <NUM> may be off-center. In other words, valve <NUM> may be asymmetrical about the central longitudinal axis <NUM> in one or more examples described herein.

Additionally, <FIG> shows that valve aperture <NUM> may be substantially ovular (e.g., elliptically) shaped in the open configuration. The ovular shape of the valve aperture <NUM> may reduce the force required to maintain valve <NUM> in closed configuration while also permitting valve <NUM> to open via peristaltic forces acting upon valve <NUM> as described above. While the example shown in <FIG> illustrates an ovular-shaped valve aperture <NUM>, other examples are contemplated in which the shape of valve aperture <NUM> may be circular, triangular, star-shaped, square, rectangular, etc. Additionally, in some examples the valve aperture <NUM> may include one or more structures including flaps, leaflets, channels, slits, cuts, grooves, etc. Further, valve aperture <NUM> designs which combine the various geometric shapes, orientations and structures are contemplated.

<FIG> illustrates an example device and method for forming (e.g., heat setting) the stent structure including stent scaffold <NUM> formed from filaments <NUM> as shown and described above. For example, <FIG> illustrates an example stent shaping mandrel <NUM> which is mounted on (e.g., engaged with) an external stent fixture device <NUM>. As illustrated in <FIG>, stent shaping mandrel <NUM> may include a first mandrel segment <NUM> and a second mandrel segment <NUM>. External stent fixture <NUM> may hold first mandrel segment <NUM> in a fixed position relative to second mandrel segment <NUM> with a gap between first mandrel segment <NUM> and second mandrel segment <NUM> such that first mandrel segment <NUM> is spaced away from second mandrel segment <NUM> and not directly contacting one another. Additionally, shaping mandrel <NUM> may further include a compressive member <NUM>. Compressive member <NUM> may be positioned in the gap between the first mandrel segment <NUM> and the second mandrel segment <NUM>. Compressive member <NUM> may include a narrowed aperture (e.g., opening, pinch point, etc.) <NUM>. In some instances, compressive member <NUM> may comprise a plurality of circumferentially arranged dies circumferentially arranged about a central longitudinal axis extending through first and second mandrel segments <NUM>, <NUM>. The plurality of dies may be radially movable toward and away from central longitudinal axis to adjust the size of the narrowed aperture <NUM>.

As will be illustrated and described below, stent shaping mandrel <NUM> may be utilized to change the shape (e.g., form) of a straight, cylindrical tubular, braided stent scaffold into a more complex-shaped stent scaffold such as stent scaffold <NUM> shown in <FIG> (which includes enlarged portions <NUM>, tapered portions <NUM>/<NUM> and narrowed region <NUM>). In order to form the complex scaffold <NUM> shape illustrated in <FIG>, it may be desirable to utilize a stent fixture device <NUM> to manipulate the various components of the shaping mandrel <NUM> shown in <FIG>. For example, the fixture device <NUM> may include a frame <NUM> attached between first mandrel segment <NUM> and second mandrel segment <NUM> and maintain first and second mandrel segments <NUM>, <NUM> a fixed distance apart. In some instances, frame <NUM> may include an adjustment mechanism (e.g., an adjustment screw) which may allow a user to adjust the distance between the first mandrel segment <NUM> and the second mandrel segment <NUM> to a desired fixed distance. Additionally, adjusting the distance between the first mandrel segment <NUM> and the second mandrel segment <NUM> may also alter their distance from the compressive member <NUM>. The distance between the first mandrel segment <NUM> and the second mandrel segment <NUM> may control the shape of the first tapered region <NUM> and the second tapered region <NUM> described above with respect to <FIG>.

<FIG> illustrates a cross-sectional view of the shaping mandrel <NUM> shown in <FIG>. <FIG> shows shaping mandrel <NUM> removed from the fixture device <NUM> described above. As described above, <FIG> shows shaping mandrel <NUM> including first mandrel segment <NUM>, second mandrel segment <NUM> and compressive member <NUM> (positioned between first mandrel segment <NUM> and second mandrel segment <NUM>). As described above, <FIG> shows that the compressive member <NUM> may include a narrowed aperture <NUM> (e.g., opening, pinch point, etc.). It can be appreciated that the narrowed aperture <NUM> of compressive member <NUM> may be utilized to form the narrowed region <NUM> of the tubular scaffold <NUM> shown in <FIG>. The narrowed region <NUM> of tubular scaffold <NUM> of <FIG> may be referred to as a "necked" region. Additionally, <FIG> illustrates that shaping mandrel <NUM> may include a first raised annular rim <NUM> and a second raised annular rim <NUM>. First annular rim <NUM> may be provided with first mandrel segment <NUM> and second annular rim <NUM> may be provided with second mandrel segment <NUM>. As will be shown and described below with respect to <FIG>, first and second raised annular rims <NUM> may be utilized to form the enlarged portions <NUM> or flanges of the tubular scaffold <NUM> shown in <FIG>. Furthermore, fixture device may include a first saddle <NUM> and a second saddle <NUM> configured to be placed around the first mandrel segment <NUM> and the second mandrel segment <NUM>, respectively, to clamp a braided tubular scaffold to the shaping mandrel <NUM>. For instance, a first end region of the braided tubular scaffold can be clamped between the first saddle <NUM> and the first mandrel segment <NUM> and a second end region of the braided tubular scaffold can be clamped between the second saddle <NUM> and the second mandrel segment <NUM>.

An example method to form tubular scaffold <NUM> may include positioning a straight, cylindrical tubular braided scaffold around shaping mandrel <NUM> (shown in <FIG>) followed by the application of a heat treatment to anneal the stent filaments <NUM> (shown in <FIG>) in a preferred shape (e.g., the shape dictated by the shaping mandrel <NUM>). For example, <FIG> illustrates an example cylindrical tubular braided scaffold <NUM> which has been positioned (e.g., disposed) around first mandrel segment <NUM> and second mandrel segment <NUM>, having first and second end regions clamped to the first and second mandrel segments <NUM>, <NUM> with first and second saddles <NUM> and <NUM>, respectively. Braided tubular scaffold <NUM> may be formed from one or more interwoven filaments <NUM> formed into a cylindrical structure. <FIG> further illustrates braided scaffold <NUM> disposed along first mandrel segment <NUM> and second mandrel segment <NUM>, with raised annular rims <NUM> positioned in the lumen of the braided scaffold <NUM> such that filaments <NUM> of braided scaffold <NUM> conform to the curvature/shape of the raised annular rims <NUM>. It can be appreciated that first saddle or clamp <NUM> and second saddle or clamp <NUM> may be designed to grasp and hold the braided scaffold <NUM> along the outer surface of both first mandrel segment <NUM> and second mandrel segment <NUM>, respectively. Additionally, first saddle or clamp <NUM> may be positioned proximate the first raised annular rim <NUM> to instill a first ridge portion <NUM> in the braided scaffold <NUM> and second saddle or clamp <NUM> may be positioned proximate the second raised annular rim <NUM> to instill a second ridge portion <NUM> in the braided scaffold <NUM>. Both first ridge portion <NUM> and second ridge portion <NUM> may extend radially away from other portions of braided scaffold <NUM>. Additionally, both first ridge portion <NUM> and second ridge portion <NUM> may extend circumferentially around the outer surface of braided segment <NUM>.

It can be appreciated from <FIG> that the shape of each of first ridge portion <NUM> and second ridge portion <NUM> may define a particular shape of the tubular scaffold <NUM> after a heat treatment is applied to the braided cylindrical scaffold <NUM>. For example, after heat treating the braided scaffold <NUM> shown in <FIG>, the first ridge portion <NUM> and second ridge portion <NUM> may correspond to the enlarged portions or flanges <NUM> of the tubular scaffold <NUM> shown in <FIG> and <FIG>. Similarly, it can be appreciated that the outer diameter of first end portion <NUM> and second end portion <NUM> of the tubular scaffold <NUM> shown in <FIG> and <FIG> may correspond to the outer diameter of first mandrel segment <NUM> and second mandrel segment <NUM> shown in <FIG>.

<FIG> further illustrates that shaping mandrel <NUM> may form a narrowed (e.g., necked) region in braided scaffold <NUM> by passing stent filaments <NUM> through the narrowed aperture <NUM> of the compressive member <NUM>. For example, <FIG> illustrates filaments <NUM> tapering radially inward from first mandrel segment <NUM> to the narrowed aperture <NUM> and tapering radially inward from second mandrel segment <NUM> to the narrowed aperture <NUM>, with filaments of braided scaffold <NUM> extending through narrowed aperture <NUM>. In some instances, one or more dies of compressive member <NUM> may be actuated radially inward to radially constrain filaments <NUM> of braided scaffold <NUM> at narrowed aperture <NUM> to a reduced diameter, with tapered portions <NUM> and <NUM> on either side of compressive member <NUM>. The compressive member <NUM> may restrain the diameter of the braided scaffold <NUM> at the necked region to a diameter of Dc or less of the finished stent <NUM>, as described above. Additionally, it can be appreciated that first tapered portion <NUM> of braided scaffold <NUM> and second tapered portion <NUM> of the braided scaffold <NUM> may correspond to first tapered region <NUM> and second tapered region <NUM> of the tubular scaffold <NUM> of stent <NUM> shown in <FIG>.

With the filaments <NUM> of the tubular braid scaffold <NUM> held in a desired configuration with the shaping mandrel <NUM>, the tubular braid scaffold <NUM> can be subjected to a heat treatment process to anneal the stent filaments <NUM> in a preferred formed shape. Thereafter, the braided scaffold <NUM> may be removed from the shaping mandrel <NUM>, while retaining its formed shape to be used as the tubular scaffold <NUM> of the stent <NUM>.

It can further be appreciated that the configuration that braided scaffold <NUM> embodies after being removed from the shaping mandrel <NUM> may be considered its "nominally deployed" configuration. In other words, the heat treatment process applied to the braided scaffold <NUM> during the forming process described above may impart a shape-memory configuration in which the scaffold <NUM> will revert to when unconstrained by an external force. This shaped memory configuration may be referred to as the stent's "nominally deployed" configuration. For example, if scaffold <NUM> is radially expanded to a diameter greater than its "nominally deployed" diameter, it will return to its "nominally deployed" diameter once the force which is maintaining the scaffold in the radially expanded configuration is removed. The nominally deployed configuration is important because it may define the threshold radial force imparted by the stent filaments <NUM> to maintain valve <NUM> in a closed configuration. As discussed above, this threshold force is the force for which the peristaltic contractions must overcome in order to open the valve <NUM>. Correspondingly, it provides the force imparted onto the valve <NUM> to bias the valve in the closed configuration to ensure stomach acids cannot leak back through the valve from the stomach (while a patient is lying down at rest, for example).

<FIG> shows method further process for constructing coating layer <NUM> and valve <NUM> within braided scaffold <NUM> (after braided scaffold <NUM> has been removed from shaping mandrel <NUM> as described above). As shown in <FIG>, after being removed from the shaping mandrel <NUM>, braided scaffold <NUM> may be positioned on a coating mandrel <NUM>. The coating mandrel <NUM> may be constructed of multiple components to facilitate inserting the coating mandrel <NUM> into the lumen of the tubular scaffold <NUM> and through the narrowed region. For example, a first member of the mandrel <NUM> may be inserted into the lumen of the tubular scaffold <NUM> from a first end of the tubular scaffold <NUM> and a second member of the mandrel <NUM> may be inserted into the lumen of the tubular scaffold <NUM> from a second end of the tubular scaffold <NUM>. For instance, coating mandrel <NUM> may include a female member <NUM> coupled to a male member <NUM>. The male member <NUM> may include a screw member <NUM> that may be threaded into a female threaded recess <NUM> located in female member <NUM>, for example. It can be appreciated that this male-female connection may allow coating mandrel <NUM> to be easily separated and removed after coating material <NUM> is applied to braided scaffold <NUM>.

In some instances, the outer diameter of coating mandrel <NUM> may be larger than the inner diameter of braided scaffold <NUM> being positioned thereon. It can be appreciated that designing coating mandrel <NUM> to have a larger outer diameter versus inner diameter of scaffold <NUM> may result in the scaffold <NUM> being positioned snug against the outer surface of coating mandrel <NUM> (<FIG> shows scaffold <NUM> being positioning snug on the outer surface of coating mandrel <NUM>). Further, the larger outer diameter of coating mandrel <NUM> (as compared to the inner diameter of scaffold <NUM>) may "radially expand" the scaffold <NUM> as compared to its "nominally deployed" configuration (e.g., nominally deployed diameter) as discussed above. Namely, the coating mandrel <NUM>, extending through the narrowed region <NUM>, radially expands the tubular scaffold <NUM> at the narrowed region to a diameter greater than its diameter Dc in the nominally deployed configuration in which the valve <NUM> is in the closed configuration. As will be discussed further with respect to <FIG>, it can be appreciated that after coating mandrel <NUM> is removed from the scaffold <NUM> (after applying the coating layer to the scaffold <NUM>), scaffold <NUM> may radially compress to its "nominally deployed" configuration (determined via the heat treatment process described above with respect to <FIG>) to bias the valve <NUM> to the closed configuration.

Further, it can be appreciated that coating mandrel <NUM> may be a variety of shapes and/or configurations. For example, coating mandrel <NUM> may have a profile which substantially matches the profile of the tubular scaffold <NUM> being positioned thereon. <FIG> shows coating mandrel <NUM> including a profile which substantially matches the profile of the scaffold <NUM>.

<FIG> shows spraying element <NUM> applying a spray coating <NUM> to scaffold <NUM> with coating mandrel <NUM> extending within lumen of scaffold <NUM>. The layer of material applied to scaffold <NUM> may correspond to coating layer <NUM> described in the examples above. Further, as shown in <FIG>, spraying element <NUM> may translate the full length of scaffold <NUM> while rotating tubular scaffold <NUM> and coating mandrel <NUM> together, depositing material corresponding to coating layer <NUM> accordingly.

It can further be appreciated that the shape of coating mandrel <NUM> may define the shape of valve <NUM>. For example, it can be appreciated that spray <NUM> may pass through the cells of scaffold22, forming a layer of material on the inner surface of scaffold22 at locations where scaffold <NUM> is spaced away from coating mandrel <NUM>. For instance, the detailed view of <FIG> shows coating mandrel <NUM> including a recessed portion <NUM> spacing the surface of coating mandrel <NUM> away from tubular scaffold <NUM> at narrowed region <NUM>. Recessed portion <NUM> may also be referred to as a "reservoir. " Further, recessed portion <NUM> may extend circumferentially around the entire circumference of coating mandrel <NUM>. Recessed portion <NUM> may facilitate the formation of a portion of coating layer <NUM> that extends radially inward from the inner surface of tubular scaffold <NUM>. Accordingly, the shape/contour of coating layer <NUM> forming the valve <NUM> may be determined by the profile of recessed portion <NUM>. For example, the cross-sectional shape of recessed portion <NUM> may be substantially ovular. It can be appreciated that the ovular shape created by recessed portion <NUM> may correspond to the ovular valve aperture <NUM> described above. Thus, valve <NUM> may be formed in the open configuration during the coating process.

<FIG> shows that in some instances, the outer surface of coating mandrel <NUM> will be positioned and/or aligned substantially "flush" with the inner surface of scaffold <NUM>. Depositing coating layer <NUM> along portions of coating mandrel <NUM> which are substantially flush with the interior surface of scaffold <NUM> may cause coating layer <NUM> to adhere to and/or form an integral interface with the inner surface of tubular scaffold <NUM> with the coating layer <NUM> filling open cells or interstices of tubular scaffold <NUM>. As discussed above, applying spray <NUM> along portions of coating mandrel <NUM> which are not substantially flush with the interior surface of scaffold <NUM> (e.g., recessed portion <NUM>) may result in spray <NUM> passing through the cell openings of scaffold22 and being deposited along the surfaces coating mandrel <NUM>. It can be appreciated that the recessed portions <NUM> of coating mandrel <NUM> may allow space for spray <NUM> to extend radially inward beyond the inner surface of scaffold22 such that the coating layer <NUM> is molded according to the shape of the recessed portion <NUM>. It can be further appreciated from <FIG> that coating layer <NUM> applied along surface of recessed portion <NUM> may, therefore, form the radially inward extending portions of valve <NUM> (including ovular aperture <NUM>) described above.

<FIG> shows scaffold <NUM> after coating mandrel <NUM> (e.g., coating mandrel <NUM> described with respect to <FIG>) has been removed. As discussed above, components of mandrel <NUM> (i.e., first and second members <NUM>, <NUM>) may be separated to remove coating mandrel <NUM> from lumen of tubular scaffold <NUM> to provide stent <NUM> including scaffold <NUM> and coating layer <NUM>. For instance, male member <NUM> may be unscrewed from the female member <NUM> and separated therefrom.

As described above, after stent <NUM> is removed from coating mandrel <NUM>, tubular scaffold <NUM> may radially compress and return to its "nominally deployed" configuration. In other words, filaments <NUM> may radially compress narrowed region <NUM> inward to return the scaffold <NUM> to its nominally deployed configuration described above and collapse the valve <NUM> to its closed configuration. Valve <NUM> may be formed from a deflectable and/or compressible material which would deform as coating mandrel <NUM> is removed from scaffold <NUM>. For example, after valve <NUM> has been constructed according to the method described with respect to <FIG>, its flexibility may permit the valve aperture <NUM> (described above but not shown in <FIG>) to close in response to scaffold <NUM> radially compressing and returning to its nominally deployed configuration.

<FIG> illustrates an example stent delivery system <NUM>. Stent delivery system may be utilized to advance and position the stent <NUM> described above. Accordingly, stent delivery system may include a handle member <NUM> coupled to an outer tubular member <NUM> and/or an inner member <NUM>. The inner member <NUM> may extend through the lumen of outer tubular member <NUM> and is depicted as a dotted line extending through a lumen of outer tubular member <NUM>). The inner member <NUM> may be coupled to a tip member <NUM>.

<FIG> illustrates stent <NUM> positioned over (e.g., surrounding) the inner member <NUM> (it is noted that the outer tubular member <NUM> may surround a portion of stent <NUM> and is shown in a partially retracted configuration for simplicity). As will be described in greater detail below, the inner member <NUM> may extend through the lumen of stent <NUM> (including the valve aperture <NUM> described above). It can further be appreciated that the handle member <NUM> may be utilized to retract the outer tubular member <NUM> relative to stent <NUM>, inner member <NUM> and tip member <NUM> to deploy the stent <NUM>.

As shown in <FIG>, the tip member <NUM> may include one or more tapered portions <NUM> designed to allow the tip to be easily retracted back through the lumen of stent <NUM> after stent <NUM> has been deployed at a target site. This feature is important because valve <NUM> of stent <NUM> may be radially compressed on inner member <NUM> when loaded on the inner member <NUM> with the inner member <NUM> extending through valve <NUM>. Therefore, tapered portions <NUM> are designed to minimize chance that tip member <NUM> may engage and interfere with the positioning of stent <NUM> as tip member <NUM> is retracted through the lumen of stent <NUM>, and through valve <NUM>.

<FIG> is a cross-sectional view taken along line <NUM>-<NUM> of <FIG>. As described above, <FIG> shows stent <NUM> including filaments <NUM> encircling valve <NUM>. Valve <NUM> may extend radially inward from the inner surface of the filaments <NUM> and includes an ovular valve aperture <NUM> through which the inner member <NUM> extends. As described above, valve <NUM> of stent <NUM> may be radially compressed on the inner member <NUM> in its "nominally deployed" configuration. In this configuration, the valve <NUM> (via the filaments <NUM>) may exert a radially compressive force onto the surface of the inner member <NUM>.

As discussed above with respect to <FIG>, <FIG> and <FIG>, valve <NUM> may expand radially outward to allow a bolus of nutritional material (e.g., food) <NUM> to pass through the lumen of stent <NUM> and through valve <NUM>. Further, as discussed with respect to <FIG>, in some instances it may be desirable for the valve <NUM> to expand radially outward to permit nutritional material (e.g., food, water, etc.) to pass through the lumen of stent <NUM>. For example, the stent filaments of tubular scaffold <NUM> which impart a radially compressive force inward on valve <NUM> may maintain the valve <NUM> in a closed configured while in a "nominally-deployed" state (e.g., a state in which no outside forces are acting on the stent <NUM> to move the valve <NUM> to an open configuration). However, the compressive force exerted by filaments <NUM> of tubular scaffold <NUM> on valve <NUM> must be low enough such that normal, peristaltic contractions associated with normal digestive processing (e.g., normal eating and digesting of food) will open valve <NUM>, thereby permitting the bolus of nutritional material to pass through valve <NUM> and into the stomach (while also permit vomiting contractions to expel food back through valve <NUM>.

To that end, when designing stent <NUM> (shown in <FIG>), it may be beneficial to understand the radially outward forces generated by a bolus of nutritional material passing through portions of stent <NUM>. For example, it may be beneficial to understand the minimum radially outward forces generated by a bolus of nutritional material passing through the narrowed region <NUM> of the stent <NUM>. It can be appreciated from the above discussion that the minimum radially outward forces generated by the bolus of material passing through the narrowed region <NUM> of the stent <NUM> may correspond to the maximum compressive forces exerted by filaments <NUM> of the tubular scaffold <NUM> on the valve <NUM>. For example, in some instances that stent <NUM> may be designed such that the maximum compressive forces exerted by filaments <NUM> of tubular scaffold <NUM> on valve <NUM> must be low enough to permit the minimum radially outward force generated by bolus of material to pass through the stent <NUM>. For instance, the stent <NUM> may be designed such that the maximum radially compressive force exerted by the filaments <NUM> of tubular scaffold <NUM> on valve <NUM> to close the valve <NUM> in a nominally-deployed state are less than the minimum radially outward force generated by a bolus of material passing through the stent <NUM>, in order to ensure the valve <NUM> opens sufficiently to allow the bolus of material to pass through the stent <NUM>.

<FIG> illustrates an example bolus force test fixture <NUM>. The test fixture <NUM> may be utilized to determine the radially outward forces generated by a representative bolus of material passing through the stent <NUM>. As shown in <FIG>, the test fixture <NUM> may include a first stent engagement member 94a and a second stent engagement member 94b, each of which are secured to a base <NUM>. The first stent engagement member 94a and the second stent engagement member 94b may be aligned with one another along a longitudinal axis <NUM>. As illustrated in <FIG>, each of the first stent engagement member 94a and the second stent engagement member 94b may be secured to the base <NUM> via a first engagement mount or strap 97a (utilized to secure the first stent engagement member 94a to the base <NUM>) and a second engagement mount or strap 97b (utilized to secure the second stent engagement member 94b to the base <NUM>).

Each of the first and the second stent engagement members 94a, 94b may be shaped such that they are designed to engage the first end <NUM> and the second end <NUM> of the stent <NUM> (not shown in <FIG>, but shown in <FIG>). For example, each of the first and the second stent engagement members 94a, 94b may include a first protrusion 95a (extending radially outward from the outer surface of the stent engagement member 94a) and a second protrusion 95b (extending radially outward from the outer surface of the stent engagement member 94a). It can be appreciated that the shape of each of the first engagement member 94a and the second engagement member 94b may be designed to mate with the first end <NUM> and the second end <NUM> of the stent <NUM> (not shown in <FIG>, but shown in <FIG>). For example, the first protrusion 95a and the second protrusion 95b may each be designed to mate with the enlarged portions <NUM> of the stent <NUM>.

Additionally, <FIG> illustrates that each of the first stent engagement member 94a and the second stent engagement member 94b may include a first lumen 92a and a second lumen 92b, respectively. It can be appreciated that each of the first lumen 92a and the second lumen 92b may be designed (e.g., sized) such that a bolus member <NUM> may pass therethrough. The bolus member <NUM> may resemble a spherically shaped ball designed to mimic (e.g., resemble, etc.) a bolus of nutritional material which may pass through the stent <NUM> (shown in <FIG>). While <FIG> illustrates that bolus member <NUM> spherically-shaped, other shapes are contemplated to mimic various types of nutritional material passing through the stent <NUM>.

Further, <FIG> illustrates that the bolus member <NUM> may be attached to a pull member <NUM> which may be designed to pass through the first lumen 92a and the second lumen 92b of the first stent engagement member 94a and the second stent engagement member 94b, respectively. In other words, it can be appreciated that the pull member <NUM> may be utilized to pull the bolus member <NUM> along the axis <NUM> through each of the first stent engagement member 94a and the second stent engagement member 94b, and thus through the valve <NUM> of a stent <NUM> mounted to the fixture <NUM>.

<FIG> and <FIG> illustrate the example bolus member <NUM> being pulled through the stent <NUM> described above. In particular, <FIG> illustrates the first end <NUM> of the stent <NUM> mounted to the first engagement member 94a and the second end <NUM> of the stent <NUM> mounted to the second engagement member 94b. Further, as described above, <FIG> illustrates each of the first engagement strap 97a and a second engagement strap 97b securing the first engagement member 94a and the second engagement member 94b to the base <NUM>.

Additionally, <FIG> illustrates the bolus member <NUM> aligned with the first lumen 94a along the axis <NUM>. Further, the pull member <NUM> is attached to the bolus member <NUM> while also extending through the first lumen 92a of the first engagement member 94a, the stent <NUM> (including the narrowed region <NUM>) and through the second lumen 92b of the second engagement member 94b.

<FIG> illustrates the bolus member <NUM> being pulled through the stent <NUM>. In particular, <FIG> illustrates bolus member <NUM> being pulled through the narrowed region <NUM> of stent <NUM>. It can be appreciated that to measure the radially outward forces generated by the bolus member <NUM> as the bolus member <NUM> is pulled through the stent <NUM>, one or more components of the testing fixture <NUM> may be attached (e.g., gripped, clamped, supported, etc.) to a force measurement machine (e.g., a tensile testing machine, Instron® machine, etc. It is noted that, for simplicity, the force testing machine is not shown in <FIG> or <FIG>). For example, in some instances, the base <NUM> may be secured to one portion of the force testing machine while the pull member <NUM> may be attached to another portion of the force testing machine.

Further, the force testing machine may be designed to "pull" the pull member <NUM> (which is attached to the bolus member <NUM>) through the stent <NUM>, as indicated by the arrow <NUM> in <FIG>. As the pull member <NUM> pulls the bolus member <NUM> through the stent <NUM> (e.g., through the narrowed region <NUM> of stent <NUM> as shown in <FIG>), the force testing machine may continuously record the radially outward forces generated by the bolus member <NUM> as it advances through the stent <NUM>, as a function of the axial force measured. It can be appreciated that the speed with which the bolus member <NUM> is pulled through the stent <NUM> may be varied to better understand how the stent reacts (e.g., the force variations placed upon the stent <NUM>) as the bolus member <NUM> passes through the stent <NUM> at varying speeds.

Claim 1:
An expandable stent (<NUM>), comprising:
a tubular scaffold (<NUM>) formed of one or more interwoven filaments (<NUM>), the tubular scaffold (<NUM>) including an inner surface; and
a flexible valve (<NUM>) extending radially inward from the inner surface of the scaffold (<NUM>);
wherein the valve (<NUM>) is configured to shift between a closed configuration and an open configuration;
wherein the one or more filaments (<NUM>) of the scaffold (<NUM>) bias the valve (<NUM>) to the closed configuration while in a nominally deployed state,
wherein the tubular scaffold (<NUM>) includes a first tapered region (<NUM>) and a second tapered region (<NUM>), and wherein the valve (<NUM>) is positioned between the first tapered region (<NUM>) and the second tapered region (<NUM>).