Adjustable mandrel for forming a stent with anti-migration features

Abstract

The present invention relates to a mandrel for forming a stent having a tapered profile and one or more anti-migration features, comprising a first stent-forming section having a first diameter, a second stent-forming section having a second diameter less than the first diameter, and a tapered section disposed therebetween. A third stent-forming section is releasably secured to the second stent-forming section and has a third diameter greater than the second diameter. One or more removable pins can extend outwardly from corresponding orifices formed in the tapered section. An actuating element can engage with the first stent-forming section and include a tapered surface configured to engage the one or more removable pins and support the one or more removable pins extending from the corresponding orifices.

Description

[0001] This application is a divisional application of application number 201880061442.3, application date 2018.7.26, invention name “Adjustable core shaft for forming a stent with anti-migration features”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Application Serial No. 62 / 537,761, filed on July 27, 2017, which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to a mandrel for forming a stent having anti-migration features. More particularly, the present disclosure relates to an adjustable mandrel for forming a stent having anti-migration features. Background Art

[0005] Stents can be configured to be positioned in a body cavity for various medical applications. In some cases, for example, stents can be used to treat vascular stenosis, to maintain fluid openings or pathways in blood vessels, the urethra, the bile duct, the trachea, the esophagus, or the renal tract, or to position devices such as artificial valves or filters within a body cavity. In some cases, a stent can include anti-migration features to help anchor the stent in any suitable location within the body cavity in which the stent is placed. In some cases, accurately and repeatedly forming these anti-migration features can be difficult. Summary of the Invention

[0006] The present disclosure relates to several alternative designs, materials and manufacturing methods for medical device structures and components, and their uses. An exemplary device for manufacturing a medical device structure is a core shaft for forming an anti-migration stent. The core shaft includes a core shaft body having a bore extending within the core shaft body and one or more orifices radially disposed about the core shaft body. One or more removable pins can extend outwardly from the one or more orifices. The core shaft also includes an actuating element that can engage with the bore extending within the core shaft body and includes a tapered surface configured to engage the one or more removable pins, the actuating element being actuatable relative to the core shaft body such that the tapered surface supports the one or more removable pins extending from the one or more orifices.

[0007] Alternatively or additionally to any of the above embodiments, the mandrel body can include a first stent-forming section having a first diameter, a second stent-forming section having a second diameter smaller than the first diameter, and a tapered section disposed between the first and second stent-forming sections.

[0008] Alternatively or additionally to any of the above embodiments, the mandrel may further include a third stent-forming segment releasably secured to the second stent-forming segment, the third stent-forming segment having a third diameter greater than the second diameter.

[0009] Alternatively or additionally to any of the above embodiments, the one or more movable pins may include a plurality of pins, and the one or more apertures may include a plurality of apertures, such that a pin may be disposed within each of the plurality of apertures.

[0010] Alternatively or additionally to any of the above embodiments, at least some of the plurality of pins have the same length.

[0011] Alternatively or additionally to any of the above embodiments, the plurality of apertures are equally spaced around the circumference of the tapered section.

[0012] Alternatively or additionally to any of the above embodiments, the corresponding aperture extends through the tapered section and is configured such that the pin extends orthogonally to the tapered surface of the tapered section.

[0013] Alternatively or additionally to any of the above embodiments, the respective apertures extend through the tapered section and are configured such that the pins extend at different angles relative to the tapered surface of the tapered section.

[0014] Alternatively or additionally to any of the above embodiments, the end of each of the one or more removable pins includes a recessed slot configured to receive a wire of a stent formed on the mandrel.

[0015] Another example apparatus is a mandrel for forming a stent having a tapered outer profile and anti-migration features. The mandrel includes a mandrel body comprising a first stent-forming section, a second stent-forming section, and a tapered section disposed between the first and second stent-forming sections. The first stent-forming section has a first diameter and a first threaded aperture extending therein, the second stent-forming section has a second diameter smaller than the first diameter and a second threaded aperture extending therein, the tapered section comprising a tapered surface. A plurality of apertures extend through the tapered surface. The mandrel includes a plurality of movable pins, each of the plurality of movable pins being extendable outwardly from one of the plurality of apertures, the plurality of movable pins being configured to form the anti-migration features of the stent. The mandrel includes a mandrel cap releasably secured to the second stent-forming section, the mandrel cap including a third stent-forming section having a third diameter greater than the second diameter. An actuating element includes a tapered end configured to engage the plurality of movable pins and a threaded body configured to threadably engage the first threaded aperture. Rotating the actuation element causes the actuation element to advance into the first stent-forming section such that the tapered end drives the plurality of movable pins in an outward direction.

[0016] Alternatively or additionally to any of the above embodiments, the third diameter is equal to the first diameter.

[0017] Alternatively or additionally to any of the above embodiments, at least some of the plurality of pins have the same length.

[0018] Alternatively or additionally to any of the above embodiments, at least some of the plurality of pins have different lengths.

[0019] Alternatively or additionally to any of the above embodiments, the end of each of the plurality of movable pins includes a recessed slot configured to receive a wire of a stent formed on the mandrel.

[0020] Alternatively or additionally to any of the above embodiments, a plurality of apertures extend through the tapered section and are configured to extend the pins orthogonally to the tapered surface of the tapered section.

[0021] Alternatively or additionally to any of the above embodiments, a plurality of apertures extend through the tapered section and are configured to cause the pin to extend at different angles relative to the tapered surface of the tapered section.

[0022] An exemplary method can be found in a method for manufacturing a stent having an anti-migration feature. A knitted stent blank can be placed in position on a mandrel comprising a tapered outer surface and one or more anti-migration feature-forming elements. Wires of the knitted stent blank can be engaged with the one or more anti-migration feature-forming elements, and the knitted stent blank can be annealed while placed on the mandrel to form a shaped stent having an anti-migration feature. The one or more anti-migration feature-forming elements can be disengaged to remove the shaped stent from the mandrel.

[0023] Alternatively or additionally to any of the above embodiments, one or more anti-migration feature forming elements include a pin configured to be driven in a radially outward direction relative to the central longitudinal axis of the core shaft, and engaging the wire with the one or more anti-migration feature forming elements includes driving the pin in a radially outward direction relative to the central longitudinal axis of the core shaft.

[0024] Alternatively or additionally to any of the above embodiments, disengaging the one or more anti-migration feature-forming elements includes moving a pin in a radially inward direction relative to a central longitudinal axis of the mandrel.

[0025] Alternatively or additionally to any of the above embodiments, placing the knitted stent blank in position on the mandrel includes stretching the knitted stent blank over the mandrel and conforming the knitted stent blank to the tapered outer surface of the mandrel.

[0026] The above summary of some example embodiments is not intended to describe each disclosed embodiment or every implementation of various aspects of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A more complete understanding of various aspects of the present disclosure may be obtained by considering the following detailed description of various embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a perspective view of an adjustable mandrel according to an embodiment of the present disclosure;

[0029] Figure 2 yes Figure 1 Exploded perspective view of the adjustable mandrel;

[0030] Figure 3 According to an embodiment of the present disclosure, Figure 1 a cross-sectional view of the adjustable mandrel wherein the pins forming the anti-migration feature are shown in a fully extended position;

[0031] Figure 4 According to an embodiment of the present disclosure, Figure 1 a cross-sectional view of an adjustable mandrel wherein the pins forming the anti-migration feature are shown in a partially extended position;

[0032] Figure 5 According to an embodiment of the present disclosure, Figure 1 a side view of a mandrel body of a portion of an adjustable mandrel;

[0033] Figure 6 yes Figure 5 A cross-sectional view of the core shaft body;

[0034] Figure 7 According to an embodiment of the present disclosure, Figure 1 a side view of a mandrel cap that is a portion of an adjustable mandrel;

[0035] Figure 8 yes Figure 7 Cross-sectional view of the central shaft cap;

[0036] Figure 9 According to an embodiment of the present disclosure, Figure 1 a perspective view of an anti-migration feature forming pin in a portion of an adjustable mandrel;

[0037] Figure 10 According to an embodiment of the present disclosure, Figure 1 a side view of a portion of an adjustable mandrel showing a portion of a knitting support disposed about the adjustable mandrel;

[0038] Figure 11 yes Figure 10 a side view of the middle knitting stand removed from the adjustable mandrel;

[0039] Figures 12A to 12D According to multiple embodiments of the present disclosure, Figure 11Schematic diagram of anti-migration features that a knitted stent may include; and

[0040] Figure 13 According to an embodiment of the present disclosure, Figure 11 A flow chart of a method for knitting a stent;

[0041] Figure 14 is a flow chart of a method of forming a knitted stent having a non-uniform profile and one or more anti-migration features according to an embodiment of the present disclosure.

[0042] Although various modifications and alternatives may be made to various aspects of the present disclosure, details thereof have been illustrated by way of example in the drawings and will be described in detail. However, it should be understood that the present invention is not intended to limit the various aspects of the present disclosure to the specific embodiments described. On the contrary, the present invention encompasses all modifications, equivalents, and alternatives falling within the scope of the present disclosure. DETAILED DESCRIPTION

[0043] For the following defined terms, these definitions shall apply unless a different definition is given in the claims or elsewhere in this specification.

[0044] Definitions for certain terms are provided below and shall apply unless a different definition is given in the claims or elsewhere in this specification.

[0045] Whether or not explicitly stated, all numerical values herein are assumed to be modified by the term "about". The term "about" generally refers to a range of values that one skilled in the art would consider to be equivalent to the stated value (i.e., having the same function or result). In many cases, the term "about" can be expressed as including values rounded to the nearest significant figure.

[0046] The recitation of numerical ranges by endpoints includes all numbers within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0047] While some suitable sizes, ranges and / or values are disclosed with respect to various components, features and / or specifications, those skilled in the art, inspired by this disclosure, will appreciate that the desired sizes, ranges and / or values may deviate from those explicitly disclosed.

[0048] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include or otherwise refer to the singular as well as the plural, unless the context clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the context clearly dictates otherwise.

[0049] The following detailed description should be read with reference to the accompanying drawings, in which similar elements are designated by the same reference numerals in different figures. The detailed description and the accompanying drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. The illustrative embodiments described are intended to be exemplary only. Selected features of any illustrative embodiment may be incorporated into the additional embodiments unless clearly indicated to the contrary.

[0050] Figure 1 FIG2 is a perspective view of a mandrel 10 for forming a stent having anti-migration features. In some cases, the stent may additionally include a tapered outer profile region having one or more flared end regions and anti-migration features. In some cases, for example, the stent may be considered to have an hourglass profile. However, in other cases, the stent may have a substantially constant outer diameter with one or more anti-migration features extending radially outward therefrom.

[0051] As seen, the mandrel 10 includes a mandrel body 12 , a mandrel cap 14 , an actuating element 16 , and a plurality of pins 18 forming an anti-migration feature. Figure 2 1 is an exploded perspective view of the mandrel 10, wherein the pins forming the anti-migration feature are not included for clarity. In some cases, the mandrel cap 14 can be releasably secured to the mandrel body 12 via bolts 34, a bayonet connection, or other securing mechanism. In some cases, the mandrel cap 14 can be removed from the mandrel body 12 to facilitate removal of the bracket from the mandrel 10. In other embodiments, the mandrel body 12 and the mandrel cap 14 can be formed as an integral or unitary structure, particularly when the mandrel cap 14 has an outer diameter that is substantially the same as that of the mandrel body 12. In some cases, the mandrel body 12 can include a cylindrical portion having an outer diameter, and the mandrel cap 14 can have an outer diameter that is larger than that of the cylindrical portion of the mandrel body 12.

[0052] Shown in Figure 1 and 2The mandrel body 12 includes a first stent-forming section 20 and a second stent-forming section 22. The first stent-forming section 20 can be a cylindrical portion of the mandrel body 12 having a first diameter, and the second stent-forming section 22 can be a cylindrical portion of the mandrel body having a second diameter. In some cases, the first stent-forming section 20 and / or the second stent-forming section 22 can have a non-cylindrical profile. For example, the first stent-forming section 20 and / or the second stent-forming section 22 can alternatively have a polygonal cross-sectional profile, such as an octagonal cross-sectional profile. This is merely an example. The first diameter can be different from the second diameter. For example, the first diameter can be greater than the second diameter. A tapered section 24 extends between the first stent-forming section 20 and the second stent-forming section 22 and defines a tapered surface 26 extending from the cylindrical outer surface of the first stent-forming section 20 to the cylindrical outer surface of the second stent-forming section 22. The tapered section 24 includes a plurality of apertures 27 extending from the tapered surface 26 through the circumferential wall of the tapered section to an internal bore extending axially within the mandrel body 12 to accommodate the anti-migration feature-forming pin 18. It will be appreciated that the angle of the tapered surface 26 relative to the first stent-forming section 20 and / or the second stent-forming section 22 can affect the relative angle at which the anti-migration feature-forming shaft 18 extends outwardly from the tapered surface 26.

[0053] In some cases, particularly where the first and second stent-forming sections 20 and 22 have similar or identical outer diameters, the tapered surface 26 itself may not be tapered, but may instead have a constant outer diameter. In some cases, at least some of the plurality of apertures 27 may have a major dimension that is orthogonal to the tapered surface 26. In some cases, at least some of the plurality of apertures 27 may have a major dimension that extends at an acute angle relative to the tapered surface 26. It will be appreciated that in some cases, some of the plurality of apertures 27 may extend at different angles relative to the tapered surface 26. As shown, the plurality of apertures 27 may be considered to be radially aligned on an annulus extending around the tapered section 24. In some cases, it will be appreciated that some of the plurality of apertures 27 may be axially displaced relative to others of the plurality of apertures 27. In other words, some of the plurality of apertures 27 may form a first annulus about the conical section 24 , while others of the plurality of apertures 27 may form a second annulus about the conical section 24 , the second annulus being axially offset from the first annulus about the conical section 24 .

[0054] In some cases, at least some of the plurality of apertures 27 may extend linearly through the tapered section 24, such that a corresponding individual pin 18 extends through the aperture 27 orthogonal to the tapered surface 26. In some cases, at least some of the apertures 27 may have a curved or spiral shape, such that as a corresponding pin 18, which may have a complementary curved or spiral shape, extends out of the aperture 27, the pin 18 may rotate, and thus the distal end of the pin 18, such as the pin end 62, may move radially as well as axially.

[0055] The actuating element 16 may be configured to extend from one end of the spindle body 12 (e.g., the end of the spindle body opposite the spindle cap 14) into the bore of the spindle body 12 to selectively engage and actuate the pin 18 within the aperture 27. For example, the actuating element 16 ( Figure 2 The actuating element 16 (shown in FIG. 1 ) includes a tapered end portion 28, as shown in subsequent figures, which can be configured to engage the pin 18 forming the anti-migration feature, and a threaded body 30 configured to threadably engage a threaded aperture extending within the first stent-forming section 20 of the mandrel body 12. In some cases, the tapered end portion 28 can taper conically, frustoconically, convexly, or concavely. The actuating element 16 can be viewed as including a handle 32 that can be used by a person or machine to rotate the actuating element 16 and thereby advance the actuating element 16 into the bore of the mandrel body 12 by rotating it in a first direction or withdraw the actuating element 16 from the bore of the mandrel body 12 by rotating it in an opposite, second direction. Thus, the threaded body 30 can threadably engage a threaded region of the bore of the spindle body 12 to threadably advance the actuating element 16 into the bore (e.g., toward the spindle cap 14) by rotating the actuating element 16 in a first rotational direction and to withdraw the actuating element 16 from the bore (e.g., away from the spindle cap 14) by rotating the actuating element 16 in an opposite, second rotational direction. This can be, for example, Figure 3 and 4 Confirmed, Figure 3 and 4 For the Figure 1 The cross-sectional view taken along the center line 3-3 shows the bore extending completely into the mandrel body 12 ( Figure 3 ) or partially extended ( Figure 4 ) of the actuating element 16. In other cases, it is contemplated that rather than the actuating element 16 itself including a threaded region, a threaded fastener may be configured to engage a threaded bore of the spindle body 12 to actuate the actuating element 16 relative to the spindle body 12.

[0056] Figure 3The actuating element 16 is shown fully extended into the bore of the mandrel body 12, with the threaded body 30 threadably engaging a threaded region of the bore of the mandrel body 12. In particular, the bore of the mandrel body 12 includes a first threaded region 36 extending from a first end of the mandrel body 12 into the first stent-forming section 20 of the mandrel body 12, the first threaded region being configured in diameter, depth, and pitch to threadably engage the threaded body 30 of the actuating element 16. In some cases, as shown, the mandrel body 12 also includes a second threaded bore or region 38 extending from an opposite second end of the mandrel body 12 into the second stent-forming section 22 of the mandrel body 12, the second threaded bore or region being configured in diameter, depth, and pitch to threadably engage threads on a threaded fastener (e.g., a bolt or screw) 34 to secure the mandrel cap 14 in position relative to the mandrel body 12 at the second end of the mandrel body 12. In some cases, it is contemplated that, rather than utilizing a separate threaded fastener 34, the mandrel cap 14 itself may include a threaded protrusion configured to engage the second threaded bore 38. Alternatively, it is also contemplated that the second end of the mandrel body 12 may include a threaded protrusion, and the mandrel cap 14 may include a threaded bore or aperture to engage the threaded protrusion of the mandrel body 12, or may include a through-hole through which the threaded protrusion passes to threadably engage a mating threaded fastener (e.g., a nut) on an opposing side of the mandrel cap 14. In either case, the mandrel cap 14 may be secured to or removable from the mandrel body 12, particularly to facilitate removal of a formed stent from the mandrel 10. In some cases, the mandrel cap 14 may be permanently secured to the mandrel body 12, particularly where the mandrel 10 has a profile in which the outer diameter of each subsequent stent-forming segment is equal to or less than the outer diameter of the preceding stent-forming segment, and the formed stent may simply be slid off the mandrel 10 without removing the mandrel cap 14. In some cases, the mandrel body 12 may include a positioning or centering aperture 40 configured to receive a positioning or centering feature 42 extending from the mandrel cap 14, but this is not required in all cases. In some cases, rather than using fasteners 34 to secure the mandrel cap 14 to the mandrel body 12, the positioning or centering feature 42 may itself threadably engage the positioning or centering aperture 40.

[0057] like Figure 3 , the actuating element 16 is fully extended into the first threaded region 36 of the bore of the mandrel body 12. Thus, the pins 18 forming the anti-migration feature may be considered to extend radially outward through the corresponding apertures 27. In some cases, depending on the particular dimensions of the various components forming the mandrel 10, the pins 18 forming the anti-migration feature may be considered to extend radially outward as far as possible before the actuating element 16 is fully extended into the first threaded region 36 of the bore of the mandrel body 12. The base 44 of each pin 18 may be considered to engage the tapered end 28 of the actuating element 16. This may be similar to Figure 4 For comparison, Figure 4The actuating element 16 extends only partially into the first threaded region 36 of the bore of the spindle body 12. Thus, while the base 44 of each pin 18 (only two pins are shown for clarity) still engages the tapered end 28 of the actuating element 16, it can be seen that the pins 18 do not extend radially outwardly through the corresponding apertures 27. Figure 3 The center pin 18 extends that far. In some cases, such as Figure 3 and 4 As shown, the base 44 of each pin 18 can be larger than the diameter of the corresponding aperture 27 in at least one dimension. Thus, when the base 44 of the pin 18 abuts the peripheral edge of the aperture 27, the extent to which the pin 18 can extend radially outward through the aperture 27 can be limited. As a result, the pin 18 is retained within the aperture 27 and does not fall out. In some cases, the pin 18 can be completely removed by withdrawing the actuating element 16 from the bore of the mandrel body 12, causing the pin 18 to move radially into the aperture 27 and then fall into the bore of the mandrel body 12.

[0058] Figure 5 is a side view of the core shaft body 12, Figure 6 For the Figure 5 Cross-sectional view taken along centerline 6-6. As can be seen, the first stent forming section 20 has a first diameter D1 and the second stent forming section 22 has a second diameter D2 that is smaller than the first diameter D1. In other cases, the second diameter D2 may be equal to the first diameter D1, or the second diameter D2 may be larger than the first diameter D1. In some cases, although a first stent forming section 20 and a second stent forming section 22 are shown, it should be understood that the core shaft body 12 may include a third stent forming section, a fourth stent forming section, etc., depending on the desired profile of the final stent product. As will be understood, in the illustrated embodiment, the tapered section 24 has a diameter (not labeled) that tapers smoothly from D1 to D2. In some cases, it is contemplated that the tapered section 24 may alternatively have one or more step changes in diameter. In addition, it can be seen that the plurality of orifices 27 may be evenly circumferentially spaced around the periphery (e.g., circumference) of the tapered section 24. However, in other cases, at least some of the plurality of apertures 27 may be unevenly circumferentially spaced about the perimeter (eg, circumference) of the tapered section 24. In some cases, at least some of the plurality of apertures 27 may be axially offset relative to others of the plurality of apertures 27.

[0059] Figure 7 is a side view of the mandrel cap 14, Figure 8 For the Figure 7Cross-sectional view taken along centerline 8-8. In some cases, the mandrel cap 14 includes a mandrel cap body 50 and a tapered segment 52. It is contemplated that the mandrel cap 14 provides a third stent forming segment 23 having a third diameter D3. In some cases, diameter D3 may be the same as diameter D1 (the diameter of the first stent forming segment 20). In some cases, diameter D3 may be larger or smaller than diameter D1, depending on the desired properties and size of the stent to be prepared using the mandrel 10. In some cases, the diameter of the tapered segment 52 varies smoothly between diameter D3 and diameter D2 (the diameter of the second stent forming segment 22). In other cases, it is contemplated that the tapered segment 52 may alternatively have one or more stepped changes in diameter. In some cases, for example Figure 8 As shown, the spindle cap 14 may include an aperture 54 sized to receive the fastener 34 and a larger aperture 56 that receives the fastener head 35 of the fastener 34. In some cases, the fastener head 35 of the fastener 34 may be configured to receive a tool such as, but not limited to, an Allen wrench and, therefore, may include six or eight side apertures 37.

[0060] Figure 9 A perspective view of an example of a pin 18 forming an anti-migration feature. In some cases, the pin 18 may include a pin body 60 extending between a base 44 (which may have an enlarged cross-section relative to the pin body 60) and a pin end 62 opposite the base 44. As noted, the base 44 may have a larger diameter than the pin body 60, but this is not required in all cases. In some cases, the pin end 62 may be curved to form a portion of the stent wire in a curved shape. In some cases, the curved shape may be a simple curve. In some cases, the curved shape may be a compound curve, such as an undulating or wavy shape. In some cases, the pin end 62 may include a recessed slot 64 configured to accommodate a stent wire formed on the mandrel 10. In some cases, the recessed slot 64 may itself have a simple or compound curve shape, so that the stent wire extending through the recessed slot 64 forms a corresponding simple or compound curve shape. For example, in some embodiments, the recessed slot 64 may be a curved slot 64 that provides a bending area for the wire placed therein. In some cases, the recessed slot 64 may include two converging portions that converge at a point on the pin end 62 to provide the wires with a sharp bend for the anti-migration feature. In some cases, the stent formed is a knitted stent, and a knitted stent blank of constant diameter may be stretched over the mandrel 10, wherein certain wires of the knitted stent blank are disposed within the recessed curved slot 64 to form the anti-migration feature extending radially outward from the knitted tubular wall of the stent. In some cases, the stent formed is a braided stent and may be braided at appropriate locations on the mandrel 10, wherein certain wires forming the anti-migration feature are braided within the recessed curved slot 64 and extend radially outward from the braided tubular wall of the stent.

[0061] While the pin ends 62 are shown as having a curved profile and are no larger than the pin body 60 in size, it is contemplated that in some cases, the pin ends 62 may extend laterally beyond the pin body 60 and form an arcuate surface. In some cases, for example, the arcuate surfaces of each of the pin ends 62 may be aligned end-to-end and substantially form a raised ring extending around the mandrel 10. By rotating the actuating element 16 in a first rotational direction to extend the actuating element 16 into the mandrel body 12, the respective arcuate surfaces of each pin end 62 may be driven outward to form a raised ring anti-migration feature in the stent. Rotating the actuating element 16 in a second, opposite rotational direction allows the pins 18 to retract, thereby removing the stent from the mandrel 10.

[0062] Figure 10 A portion of a knitting support 70 is shown which is arranged on the core shaft 10. Figure 11 The knitting support 70 is shown removed from the core shaft 10. Figure 10 As shown, one of the wires of the knitted stent can extend radially outward from the knitted tubular wall of the stent 70, along the recessed slot 64 of the pin 18, to form one or more anti-migration features 78 of the stent 70. In some cases, a knitted stent, such as the knitted stent 70, can be formed by first knitting a constant diameter stent blank (not shown), and then stretching the constant diameter stent blank over the mandrel 10 prior to a forming process and / or annealing process. As can be seen, the knitted stent 70 has a first increased diameter portion 72 near the first end of the knitted stent 70, corresponding to the first stent-forming segment 20; a second increased diameter portion 74 near the second end of the knitted stent 70, corresponding to the third stent-forming segment 23; and a (relatively) reduced diameter portion 76 (e.g., a cylindrical body region intermediate the first increased diameter portion 72 and the second increased diameter portion 74) corresponding to the second stent-forming segment 22. The knitted stent 70 includes the anti-migration features 78 corresponding to the pin 18, which are arranged circumferentially around the knitted stent 70 in the transition region between the first increased diameter portion 72 and the reduced diameter portion 76. However, it is contemplated that the anti-migration features 78 may be disposed at various locations along the length of the knitted stent 70, if desired. After the knitted stent blank is placed on the mandrel 10, the pins 18 may be actuated radially outwardly to seat the wires in the recessed slots 64, thereby causing portions of the wire-engaging pins 18 to be pushed radially outward from the knitted tubular wall of the stent to form the anti-migration features 78.

[0063] Figure 12A7 is an end view of a knitted stent 70 showing anti-migration features 78 extending radially outward from the knitted tubular wall of the knitted stent 70. As shown, each anti-migration feature 78 is a loop of a filament or wire forming the knitted stent 70, which extends between adjacent anchor points 80, with each loop being of approximately equal shape and size. The anchor points 80 can be locations where portions of the filament or wire intersect or loop with another portion of the filament or wire. In other cases, the shape and / or size of some of the anti-migration features 78 can vary, or, for example, can be spaced unequally. Although the anti-migration features 78 are shown as curved, in some cases, the anti-migration features 78 can be sharp, or can include, for example, flat areas.

[0064] For example, Figure 12B A knitted stent 70a is shown that includes a plurality of anti-migration features 78a. Each of the anti-migration features 78a extends between adjacent anchor points 78 and are generally identical in shape and size. However, by Figure 12B and Figure 12A By comparison, we can see that Figure 12A The anti-migration characteristics shown in 78 Figure 12B , extends radially outward farther. For example, the anti-migration feature 78a can be formed by using a shorter length of the anti-migration feature-forming pin 18, or by not advancing the actuating element 16 as far into the mandrel body 12, so that the pin 18 does not advance as far radially outward from the surface of the tapered section 24 of the mandrel body 12. For example, the anti-migration feature 78a can be sharp or can have other shapes.

[0065] It should be understood that the relative sizes of the anti-migration features 78 and the anti-migration features 78a can be a function of the ultimate use of the knitted stent 70 (or 70a). Relatively larger anti-migration features 78, 78a can be used in situations where the knitted stent 70 (or 70a) will be placed in an anatomical location that may be subject to relatively strong migration forces and / or an anatomical location where the size of the patient's anatomy may vary more. Relatively smaller anti-migration features 78, 78a can be used in situations where the knitted stent 70 (or 70a) may be subject to relatively weak migration forces and / or an anatomical location where the size of the patient's anatomy is less variable. In some cases, the overall size of the knitted stent 70 (or 70a) can also play a part. In some cases, for example, a knitted stent 70 (or 70a) with a larger diameter may have relatively larger anti-migration features 78, 78a, while a knitted stent 70 (or 70a) with a smaller diameter may have relatively smaller anti-migration features 78, 78a.

[0066] Figure 12C A knitted stent 70b is shown including a number of anti-migration features 78b. Figure 12A and 12BCompared to the knitted stents 70 and 70a shown, the anti-migration features 78b are not equidistantly spaced around the perimeter of the knitted stent 78b. Each anti-migration feature 78b extends between adjacent anchor points 80, although some anchor points 80 are not attached to an anti-migration feature 78b. As shown, the shape and size of each anti-migration feature 78b are substantially identical. For example, the anti-migration features 78b can be formed by placing the pins 18 forming the anti-migration features in only some of the orifices 27. In some cases, it is contemplated that some anti-migration features 78b may be smaller or larger in size and / or may vary in shape relative to others of the anti-migration features 78b.

[0067] Figure 12D A knitted stent 70c is shown including a plurality of anti-migration features 78c and a plurality of anti-migration features 78d, each extending between adjacent anchor points 80. It should be understood that, as shown, each anti-migration feature 78c is substantially identical in shape and size, and each anti-migration feature 78d is substantially identical in shape and size, although not extending radially outward as far as anti-migration feature 78c. For example, anti-migration features 78c and 78d can be formed by using longer lengths of pins 18 to form each anti-migration feature 78c and shorter lengths of pins 18 to form each anti-migration feature 78d. It should be understood that the specific anti-migration features 78, 78a, 78b, 78c, and 78d are merely illustrative and can be mixed or matched in any desired pattern.

[0068] Figure 13 Flowchart of a method 90 for forming a knitted stent having a non-uniform profile and one or more anti-migration features. In some cases, a constant diameter knitted stent blank can be positioned on a mandrel having a tapered outer surface and one or more anti-migration feature-forming elements, generally as shown at block 92. For example, the mandrel can be mandrel 10. In some cases, positioning the constant diameter knitted stent blank on the mandrel includes stretching the constant diameter knitted stent blank on the mandrel and allowing the constant diameter knitted stent blank to conform to the varying diameter outer surface of the mandrel, thereby conforming to various constant diameter regions and / or tapered diameter regions of the mandrel.

[0069] One or more anti-migration feature forming elements (such as, but not limited to, pins 18) may be engaged, as shown in box 94, to provide the desired shape prior to annealing, as shown in box 96. In some cases, the one or more anti-migration feature forming elements are pins configured to be driven in a radially outward direction relative to the outer surface of the mandrel, and engaging the one or more anti-migration feature forming elements includes driving the pins in a radially outward direction relative to the mandrel to push the wire or filament engaging the ends of each pin in a radially outward direction relative to the knitted tubular structure of the stent. The mandrel and the stent thereon, having the anti-migration features formed thereon, may then be subjected to an annealing or shape setting process. As seen in box 98, after the annealing or shape setting process, the one or more anti-migration feature forming elements may be disengaged to remove the shaped stent from the mandrel. In some cases, disengaging the one or more anti-migration feature forming elements includes moving the pins in an inward direction relative to the mandrel.

[0070] Figure 14 1 is a flow chart of a method 100 for forming a knitted stent having a non-uniform profile and one or more anti-migration features. In some cases, a knitted stent may have a metallic component and a non-metallic, or even biodegradable, component. The metallic component and the non-metallic, or even biodegradable, component may be formed separately and then combined to form the stent. In some cases, each of the metallic component and the non-metallic, or even biodegradable, component may include an anti-migration feature, wherein the anti-migration feature of the non-metallic, or even biodegradable component supplements the anti-migration feature of the metallic component. In cases where the non-metallic component is biodegradable, the biodegradable anti-migration feature may provide additional resistance to migration after the initial implantation of the stent, but dissolves over time.

[0071] In some cases, a constant diameter metal knitted stent blank may be positioned on a mandrel having a tapered outer surface and one or more anti-migration feature-forming elements, as generally shown at block 102. For example, the mandrel may be mandrel 10. In some cases, placing the constant diameter metal knitted stent blank in position on the mandrel includes stretching the constant diameter metal knitted stent blank over the mandrel and conforming the constant diameter metal knitted stent blank to the varying diameter outer surface of the mandrel, thereby conforming to various constant diameter regions and / or tapered diameter regions of the mandrel.

[0072] One or more anti-migration feature forming elements (such as, but not limited to, pins 18) may be engaged, as shown in block 104, to provide the desired shape prior to annealing, as shown in block 106. In some cases, the one or more anti-migration feature forming elements are pins configured to be driven in a radially outward direction relative to the outer surface of the mandrel, and engaging the one or more anti-migration feature forming elements includes driving the pins in a radially outward direction relative to the mandrel to push the wire or filament engaging the ends of each pin in a radially outward direction relative to the knitted tubular structure of the stent. The mandrel and the stent thereon (having formed anti-migration features) may then be subjected to an annealing or shape setting process. As seen in block 108, after the annealing or shape setting process, the one or more anti-migration feature forming elements may be disengaged to remove the formed stent from the mandrel. In some cases, disengaging the one or more anti-migration feature forming elements includes moving the pins in an inward direction relative to the mandrel.

[0073] In some cases, once the formed metal stent is removed from the mandrel, the constant diameter biodegradable knitted stent blank may be positioned on a mandrel having a tapered outer surface and one or more anti-migration feature forming elements, generally as shown in block 110. In some cases, placing the constant diameter biodegradable knitted stent blank in position on the mandrel includes stretching the constant diameter biodegradable knitted stent blank over the mandrel and conforming the constant diameter biodegradable knitted stent blank to the varying diameter outer surface of the mandrel, thereby conforming to the various constant diameter regions and / or tapered diameter regions of the mandrel. The one or more anti-migration feature forming elements may be engaged, as shown in block 112, to provide the desired shape prior to annealing, as shown in block 114.

[0074] In some cases, the annealing process for the biodegradable knitted stent blank may involve a temperature lower than that used for the metal knitted stent blank. The mandrel and the stent thereon (having the formed anti-migration features) may then undergo an annealing or shape setting process. As seen in block 116, after the annealing or shape setting process, the one or more anti-migration feature forming elements may be disengaged to remove the formed biodegradable stent from the mandrel. In some cases, disengaging the one or more anti-migration feature forming elements includes moving a pin in an inward direction relative to the mandrel. In some cases, although not shown, the formed biodegradable stent may be disposed around or within the formed metal stent.

[0075] In some embodiments, the knitted stent 70 can be formed of any desired material, such as a biocompatible material, including a biostable material, a bioabsorbable material, a biodegradable material, or a bioerodible material. For example, the knitted stent 70 can be formed of a metallic material. Some suitable metallic materials include, but are not necessarily limited to, stainless steel, tantalum, tungsten, nickel-titanium alloys (such as those having shape memory properties, commonly known as nitinol), nickel-chromium alloys, nickel-chromium-iron alloys, cobalt-chromium-nickel alloys, or other suitable metals, or combinations or alloys thereof. In some cases, the core shaft 10 can be formed of a material that is thermally stable and does not expand at the temperature used to anneal the knitted stent 70. In some cases, for example, the core shaft 10 can be formed of a metallic material, such as stainless steel, titanium, or nickel-titanium alloys. In some cases, the core shaft 10 can be formed of a ceramic material.

[0076] In some embodiments, the knitted stent 70 may comprise one or more metals. Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloys, such as linear elastic and / or superelastic nitinol; other nickel alloys, such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625, such as 625, UNS:N06022, such as UNS:N10276, such as other alloys, etc.), nickel-copper alloys (e.g., UNS: N04400, such as 400, 400, 400, etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035, such as etc.), nickel-molybdenum alloys (e.g., UNS: N10665, such as ALLOY ), 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, etc.; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003, such as etc.); platinum-rich stainless steel; titanium; combinations thereof; etc.; or any other suitable material.

[0077] As mentioned herein, within the family of commercially available nickel-titanium, or Nitinol, alloys, there are classes referred to as "linear elastic" or "non-superelastic," which, while chemically similar to common shape memory and superelastic varieties, can exhibit unique and beneficial mechanical properties. Linear elastic and / or non-superelastic Nitinol can be distinguished from superelastic Nitinol in that linear elastic and / or non-superelastic Nitinol does not exhibit a substantial "superelastic plateau" or "flag region" in its stress / strain curve, whereas superelastic Nitinol does. In contrast, in linear elastic and / or non-superelastic Nitinol, as recoverable strain increases, stress continues to increase in a substantially linear, or somewhat linear, but not necessarily completely linear, relationship until plastic deformation begins, or at least in a more linear relationship than the superelastic plateau and / or flag region exhibited by superelastic Nitinol. Thus, for the purposes of this disclosure, linear elastic and / or non-superelastic Nitinol may also be referred to as "substantially" linear elastic and / or non-superelastic Nitinol.

[0078] In some examples, linear elastic and / or non-superelastic nitinol can also be distinguished from superelastic nitinol in that linear elastic and / or non-superelastic nitinol can withstand strains of up to about 2-5% while remaining substantially elastic (e.g., before plastic deformation), while superelastic nitinol can withstand strains of up to about 8% before plastic deformation. Both of these materials can be distinguished from other linear elastic materials, such as stainless steel (which can also be distinguished based on their composition), which can only withstand strains of about 0.2 to 0.44% before plastic deformation.

[0079] In some embodiments, the linear elastic and / or non-superelastic nickel-titanium alloy is an alloy that does not exhibit any detectable martensitic / austenitic transformations over a wide temperature range as analyzed by differential scanning calorimetry (DSC) and dynamic metallographic thermal analysis (DMTA). For example, in some embodiments, no martensitic / austenitic transformations are detected in the linear elastic and / or non-superelastic nickel-titanium alloy over a wide temperature range as analyzed by differential scanning calorimetry (DSC) and dynamic metallographic thermal analysis (DMTA). Thus, over this very wide temperature range, the mechanical bending properties of such materials are generally unaffected by temperature. In some embodiments, the mechanical bending properties of the linear elastic and / or non-superelastic nickel-titanium alloy at ambient or room temperature are substantially the same as those at body temperature, e.g., neither exhibits a superelastic plateau and / or signature region. In other words, the linear elastic and / or non-superelastic nickel-titanium alloy maintains its linear elastic and / or non-superelastic properties and / or performance over a wide temperature range.

[0080] In some embodiments, the linear elastic and / or non-superelastic nickel-titanium alloy may contain about 50 to about 60 weight percent nickel, with the remainder being essentially titanium. In some embodiments, the composition contains about 54 to about 57 weight percent nickel. An example of a suitable nickel-titanium alloy is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Some examples of nickel-titanium alloys are disclosed in U.S. Patent Nos. 5,238,004 and 6,508,803, which are incorporated herein by reference. Other suitable materials may include ULTANIUM TM (available from Neo-Metrics) and GUM METAL TM (Available from Toyota.) In some other embodiments, superelastic alloys, such as superelastic Nitinol, can be used to achieve the desired properties.

[0081] It will be understood by those skilled in the art that aspects of the present disclosure may be embodied in a variety of forms other than the specific embodiments described and contemplated herein. Therefore, departures in form and detail may be made without departing from the scope of the present invention as described in the appended claims.

Claims

1. A mandrel comprising: The core shaft body comprises: a bore extending within the mandrel body; and one or more apertures radially disposed about the mandrel body; and One or more pins extend outwardly from the one or more apertures, each pin having a pin body extending between a base and a pin end, wherein the pin end of each of the one or more pins includes a recessed slot configured to receive a wire of a stent formed on the mandrel.

2. The mandrel of claim 1, wherein the recessed slot defines a curve. The mandrel of claim 2 , wherein the curve is a compound curve.

4. The mandrel of claim 3, wherein the compound curve comprises two portions converging at a point at the pin end of each pin to provide a sharp bend in the wire.

5. A spindle according to any one of claims 1 to 4, wherein the pin end of each pin extends laterally beyond the pin body.

6. A spindle according to any one of claims 1 to 4, wherein the diameter of the base of each pin is greater than the diameter of the pin body.

7. The mandrel of any one of claims 1 to 4, wherein the one or more pins comprises a plurality of pins and the one or more apertures comprises a plurality of apertures such that a pin is disposed within each of the plurality of apertures.

8. The mandrel of any one of claims 1 to 4, wherein the one or more pins are movable, the mandrel further comprising an actuating element engageable with a bore extending within the mandrel body and comprising a surface configured to engage the one or more movable pins, the actuating element being actuatable relative to the mandrel body such that the surface supports the one or more movable pins extending from the one or more orifices to form an anti-migration scaffold.

9. The mandrel of claim 8, wherein the mandrel body comprises: a first stent-forming section having a first diameter; a second stent-forming section having a second diameter smaller than the first diameter; and A tapered section is disposed between the first stent-forming section and the second stent-forming section.

10. The mandrel of claim 9, wherein the one or more apertures extend through the tapered section and are configured to enable a pin to extend orthogonally to the tapered surface of the tapered section.

11. The mandrel of claim 9, wherein the one or more apertures extend through the tapered section and are configured to enable a pin to extend at different angles relative to the tapered surface of the tapered section.

12. A method of manufacturing a stent having a tapered profile and anti-migration features, the method comprising: placing a knitted stent blank in position on a mandrel, the mandrel comprising a tapered outer surface and a plurality of pins extending radially outwardly relative to a central longitudinal axis of the mandrel, each of the plurality of pins having a pin end with a recessed slot; engaging a wire of the knitted stent blank with a recessed slot of one of the plurality of pins to urge the wire in a radially outward direction relative to the knitted stent blank to form an anti-migration feature; annealing the knitted stent blank while positioned on the mandrel to form a shaped stent having the anti-migration characteristics; and The shaped stent is disengaged from the mandrel.

13. The method of claim 12, wherein the plurality of pins are movable between radially outward and radially inward positions relative to the central longitudinal axis of the mandrel, wherein engaging the wire with the recessed slot of one of the plurality of pins comprises driving the pin in a radially outward direction, and disengaging the shaped stent from the mandrel comprises allowing the pin to move in a radially inward direction.

14. The method of claim 13, wherein driving the pins in a radially outward direction comprises actuating an actuating element within a bore of the mandrel, the actuating element comprising a surface that engages the plurality of pins.

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