EP4680163A1

EP4680163A1 - Self-locking stent

Info

Publication number: EP4680163A1
Application number: EP24712007.4A
Authority: EP
Inventors: Rene Leonardus Jacobus Marie UBACHS; Rudolf Maria Jozef Voncken
Original assignee: Koninklijke Philips NV
Current assignee: Koninklijke Philips NV
Priority date: 2023-03-17
Filing date: 2024-03-13
Publication date: 2026-01-21
Also published as: WO2024194102A1

Abstract

A stent (100) is described and includes an outer portion comprising a collapsible closed cell mesh (102) adapted to be deployed in a lumen. The stent (100) also includes and a lock beam (604) configured to lock the collapsible closed cell mesh (102). The locking beam is adapted to tangentially increase a stiffness of the collapsible closed cell mesh (102) radially, lock beams (104) for collapsible mesh (602) stents are also described.

Description

SELF-LOCKING STENT

BACKGROUND

[0001] A stent is a tube inserted into a blocked or otherwise compromised artery or vein to keep the passageway open. When blood vessels are obstructed either by stenosis or by externally applied load, patency can be restored and maintained by the placement of a stent. The amount of patency restored is determined by the size of the stent and the amount of radial outward force that is needed to deploy the stent and the amount of chronic outward force the stent can supply after deployment.

[0002] Typically, a stent will be chosen that is oversized with respect to the target vessel. In that way the forces applied by the stenotic vessel wall can be balanced by the forces resulting from radially compressing the stent while maintaining the desired patency. As such, the stent functions as a loaded spring.

[0003] There is a trade-off between radial stiffness and deployability of many stents. Specifically, while a radially stiff stent is beneficial to provide sufficient for patency of the vessel under load, this desired radial stiffness often results in difficulty in loading the stent into a delivery device (e.g., a catheter) with a sufficiently small diameter for deployment intravascularly to a desired position (e.g., a region of a lesion).

[0004] The stent must have sufficient radial stiffness to avoid an unacceptable reduction of its diameter. Yet, placement of a stent can lead to damage of the vessel wall and/or disruption of the fluid (e.g., blood) flow because of a sudden change of vessel diameter when a large, high stiffness stent diameter is used.

[0005] What are needed are a stent that provides suitable radial stiffness when deployed, and yet can be compressed sufficiently for deployment to damaged or diseased veins and arteries.

SUMMARY

[0006] According to one aspect of the present disclosure, a stent comprises: an outer portion comprising a collapsible closed cell mesh adapted to be deployed in a lumen; and a lock beam configured to lock the collapsible closed cell mesh, the lock beam being adapted to tangentially increase a stiffness of the collapsible closed cell mesh radially, wherein the lock beam is adapted to collapse to an unlocked position when the collapsible closed cell mesh is collapsed. [0007] According to another aspect of the present disclosure, a stent comprises: an outer portion comprising a collapsible mesh adapted to be deployed in a lumen; and a lock beam configured to lock the collapsible mesh tangentially, the lock beam being adapted to increase a stiffness of the collapsible mesh radially, wherein the lock beam comprises a plurality of collapsible sections.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The example embodiments are best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever applicable and practical, like reference numerals refer to like elements.

[0009] Fig. 1A is a perspective view of a stent comprising a plurality of lock beams in accordance with a representative embodiment.

[0010] Fig. IB is a perspective view of a portion of the stent of Fig. 1 A showing the lock beams positioned to provide a nominal diameter of the stent in accordance with a representative embodiment.

[0011] Fig 1C is a perspective view of a stent comprising a plurality of lock beams in a collapsed state in accordance with a representative embodiment.

[0012] Fig. ID is perspective view of a portion of the stent of Fig. 1C showing the compressible mesh and lock beams in the collapsed state in accordance with a representative embodiment. [0013] Fig. IE is another perspective view of a portion of the stent of Fig. 1C showing the compressible mesh and lock beams in the collapsed state in accordance with a representative embodiment.

[0014] Fig. IF is another perspective view of the stent of Fig. 1 A showing the compressible mesh and lock beams in a collapsed state in accordance with a representative embodiment. [0015] Fig. 2A shows a tangential (top) and radial (bottom) views of a section of a stent including lock beams before compression for deployment in accordance with a representative embodiment.

[0016] Fig. 2B shows a tangential (top) and radial (bottom) views of a section of a collapsible closed cell mesh of a stent including lock beams in a partially collapsed state for deployment in accordance with a representative embodiment. [0017] Fig. 2C shows a tangential (top) and radial (bottom) views of a section of a section of a collapsible closed cell mesh of a stent including lock beams in a collapsed state for deployment in accordance with a representative embodiment.

[0018] Fig. 2D shows a tangential (top) and radial (bottom) views of a section of a section of a collapsible closed cell mesh of a stent including lock beams in a locked state after deployment in accordance with a representative embodiment.

[0019] Fig. 3 A is a side view of a stent comprising a plurality of lock beams in a locked state accordance with a representative embodiment.

[0020] Fig. 3B is a perspective view of the stent of Fig. 3 A showing the stent comprising a plurality of lock beams in a locked state in accordance with a representative embodiment.

[0021] Fig. 4A is a perspective view of a portion of the stent of Fig. 1 A showing the lock beams positioned to provide a nominal diameter of the stent in accordance with a representative embodiment.

[0022] Fig 4B is a perspective view of a stent comprising a plurality of lock beams in a collapsed state in accordance with a representative embodiment.

[0023] Fig. 4C is a side view of the stent of Fig. 4A.

[0024] Fig. 5 is a flow-chart of a method for deploying a stent in accordance with a representative embodiment.

[0025] Fig. 6A is a perspective view of a compressible mesh stent comprising lock beams in a deployed position adapted to increase radial stiffness of the stent in accordance with a representative embodiment.

[0026] Fig. 6B is a side view of the compressible mesh stent of Fig. 6A comprising lock beams in a deployed position adapted to increase radial stiffness of the stent in accordance with a representative embodiment.

[0027] Fig. 6C is a perspective view of the compressible mesh stent of Fig. 6A comprising lock beams in a collapsed state for deployment in accordance with a representative embodiment.

DETAILED DESCRIPTION

[0028] In the following detailed description, for the purposes of explanation and not limitation, representative embodiments disclosing specific details are set forth in order to provide a thorough understanding of the various embodiments according to the present teachings. However, other embodiments consistent with the present disclosure that depart from specific details disclosed herein remain within the scope of the appended claims. Descriptions of known systems, devices, materials, methods of operation and methods of manufacture may be omitted so as to avoid obscuring the description of the representative embodiments. Nonetheless, systems, devices, materials and methods that are within the purview of one of ordinary skill in the art are within the scope of the present teachings and may be used in accordance with the representative embodiments. It is to be understood that the terminology used herein is for purposes of describing particular embodiments only and is not intended to be limiting. Definitions and explanations for terms herein are in addition to the technical and scientific meanings of the terms as commonly understood and accepted in the technical field of the present teachings.

[0029] It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the inventive concept. [0030] As used in the specification and appended claims, the singular forms of terms ‘a’, ‘an’ and ‘the’ are intended to include both singular and plural forms, unless the context clearly dictates otherwise. Additionally, the terms "comprises", and/or "comprising," and/or similar terms when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0031] As used in the specification and appended claims, and in addition to their ordinary meanings, the term “approximately” mean to with acceptable limits or degree. For example, “memory wires are heated to approximately the same temperature” means one of ordinary skill in the art would consider the temperatures of memory wires are the same within reasonable measure.

[0032] As used in the specification and appended claims, in addition to their ordinary meanings, the term ‘substantially’ means within acceptable limits or degree. For example, the “plurality of first memory wires is substantially the same” means one of ordinary skill in the art would consider the first memory wires to be the same.

[0033] Unless otherwise noted, when an element or component is said to be “connected to”, or “coupled to another element or component,” it will be understood that the element or component can be directly connected or coupled to the other element or component, or intervening elements or components may be present. That is, these and similar terms encompass cases where one or more intermediate elements or components may be employed to connect two elements or components. However, when an element or component is said to be “directly connected” to another element or component, this encompasses only cases where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0034] The present teachings relate generally to providing a stent that affords improved radial stiffness after deployment by the inclusion of lock beams to buttress the strength of the stent in the radial direction resulting in a minimum diameter stent once deployed. This minimum diameter results in the desired maintaining of patency once deployed. Notably, in certain embodiments, the stent is disposed at a nominal diameter that provides a greater diameter of the stent once deployed. Accordingly, the stent maintains some desired elasticity. Prior to deployment, the stent including the lock beam is compressed for disposition in a delivery device for deployment, such as a catheter. After deployment, the stent expands to it desired diameter/size and reaches equilibrium providing a structure that can expand with an expansion of the vein or artery, for example, yet will not compress to a diameter/size less than the minimum diameter. Accordingly, in accordance with various representative embodiments, the radial stiffness of a stent is improved using a lock beams. Lock beams allow a flexible stent to be compressed for deployment become much more rigid after deployment. Notably, however, and as described more fully below, the manner of implementing the locking of the stent does not involve overlapping structures in the final configuration, unlike certain known locking mechanisms. As a result, the stents of the present teachings provide less obstruction to blood flow. Moreover, the stents of the present teachings are adapted to be radially compressed further compared to overlapping lock structures, which facilitates loading into the delivery device and delivering it intravascularly to the region under treatment.

[0035] Fig. 1 A is a perspective view of a stent 100 comprising a plurality of lock beams 104 in a closed cell mesh 102 comprising struts 103 in accordance with a representative embodiment. [0036] The lock beams 104 are disposed around a circumference of the closed cell mesh 102 tangentially (0 direction in the cylindrical coordinate system of Fig. 1 A) provided added stiffness to the collapsible closed cell mesh 102 in the radial direction (r direction in the cylindrical coordinate system of Fig. 1A). Notably, and as more clearly shown in Fig. IB, the stent 100 is at a nominal diameter having some elasticity to expand (+r direction) and compress (-r direction), but is not disposed at the minimum radius. As such, at the nominal diameter, the sections of the lock beams 104 are separated from struts 103 by a gap, whereas in the locked position, there is no gap between the sections of the lock beams 104 and the struts 103 of the closed cell mesh 102.

[0037] The closed cell mesh 102 is illustratively collapsible, which is useful when compressing the stent 100 for disposition in a delivery device (not shown) and providing some elasticity once deployed. The material selected for the closed cell mesh 102 may be one commonly adapted for use in stents, including Ni-Ti alloys, such as Nitinol or some other biocompatible material. Other metallic materials contemplated for use as the closed cell mesh include, but are not limited to cobalt-cromium alloys (e.g., Elgiloy), stainless steel, and titanium, iron or magnesium based alloys. Moreover, polymeric materials such as polyethylene terepthalate (PET), poly-L-lactic acid (PLLA) and poly-l-glycolic acid (PLGA) may also be used. The stents may also be coated for example with a drug eluting layer. In certain embodiments, so-called super-elastic materials such as shape memory alloy (e.g., Nitinol) may be used for the closed cell mesh enabling deployment in the artery or vein where the super or pseudo elastic properties of these materials are beneficial so the closed cell mesh expands to its final dimension. Alternatively, the closed cell mesh 102 may be expanded once deployed in-situ using a balloon or other known device. [0038] The lock beams 104 comprise sections of circles disposed tangentially around the circumference of the closed cell mesh 102. As noted above and described more fully below, when the stent 100 is compressed, the sections of the lock beams contact the nearest strut 103 of the closed cell mesh 102 forming a circle that defines the minimum radius, and the maximum compression, of the closed cell mesh 102, and thus the stent 100. Generally, the lock beamsl04 comprise same material as the stent, and may be constructed during a laser cutting process at the same time as the other struts are created. The lock beams 104 may also be fabricated using known additive manufacturing techniques. In the latter case the lock beams 104 may be created simultaneously with the creation of the cell structure of the stent and can consist of the same or different material then the closed cell mesh 102. Moreover, lock beams of various representative embodiments may also be added to an existing stent, such as using known additive manufacturing techniques. The material of the lock beams may be any biocompatible material similar to those used for stents.

[0039] The spacing (along the z-direction) of the lock beams 104 is selected to provide a desired degree of stiffness when the stent 100 is compressed to the minimum radius. As will be appreciated, smaller spacing of the lock beams 104 increases the stiffness in the radial direction at each point along the length (z-direction) of the stent 100. Similarly, greater spacing of the lock beams 104 will provide less stiffness in regions between lock beams 104 allowing greater collapse of the closed cell mesh 102 in the regions between the lock beams. As such, the selection of the spacing between the lock beams also impacts the stiffness of the stent in the radial direction along the length of the stent.

[0040] It may be desirable for example for the ends of the stent 100 to have a higher compliance (lower stiffness) while the central part of the stented vessel achieves the desired patency. This allows that the lumen of the stented vessel to have a gradual diameter change, which is beneficial for the blood flow (It avoids or reduces turbulent blood flow which may induce thrombus formation such as described in Stein, P.D. and Sabbah, H.N. (1974) “Measured Turbulence and Its Effect on Thrombus Formation’, Circulation Research, 35(4), pp. 608-614. Available at: https://doi.Org/10.1161/01.RES.35.4.608.)).

[0041] The axial spacing between circumferential lock beams 104 is illustratively between 1 and 3 times the diameter of the stent. Shorter distances between the lock beams 104 will not significantly increase the radial stiffness, while at separation distances greater than 1.5 times the diameter the stiffness increase will be diminished. Notably, the distance between lock beams 104 is affected by the size of the cells in the closed cell mesh 102. Additionally, the positioning of the lock beams also affects the flexural stiffness of the stent along the axial direction. In an extreme example in which every closed cell of the stent 100 is enhanced with a lock beam, the stent becomes almost fully rigid not only in radial direction, but also along its axial direction. [0042] Fig. IB is a perspective view of a portion of the stent 100 of Fig. 1 A showing the lock beams 104 positioned to provide a nominal diameter (r-direction of the cylindrical coordinate system of Fig. IB) of the stent in accordance with a representative embodiment. Various aspects and details of the portion of the stent described in connection with Fig. IB are common to those of the stent 100 described above in connection with Fig. 1 A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0043] The lock beams 104 are disposed around a circumference of the closed cell mesh 102 tangentially (0 direction in the cylindrical coordinate system of Fig. 1 A) provided added stiffness to the collapsible closed cell mesh 102 in the radial direction (r direction in the cylindrical coordinate system of Fig. 1 A). The lock beams 104 each comprise a number of sections 106 separated by gaps 108. In this state with the gaps 108 exist between the sections 106 of the lock beams 104 and the nearest strut 103, the stent 100 has a nominal diameter. As such, the stent 100 has some elasticity allowing for a reduction in the diameter of the stent, and of course, the increase of the diameter of the stent should the need arise. Illustratively, once deployed, the stent 100 has the nominal diameter providing a degree of resilience. As such, the stent 100 is at a nominal diameter having some elasticity to expand (+r direction) and compress (-r direction), but is not disposed at the minimum radius. As discussed more fully below, when compressed, the gaps 108 between the sections 106 of the lock beams reduces and at the minimum diameter the gaps 108 disappear causing the lock beams 104 to have a substantially circular shape. In this position, which may be referred to as a locked position, the lock beams 104 are adapted to tangentially increase a stiffness of the collapsible closed cell mesh 102 radially (r-direction). However, and as described more fully below, the lock beams are adapted to collapse inwardly (towards to central axis (z-direction in the coordinate system of Fig. IB) to an unlocked position when the collapsible closed cell mesh 102 is collapsed, for example for deployment. Again, the above noted gaps between the lock beams 104 are chosen to enable greater for more axial flexibility of the stent 100.

[0044] Fig 1C is a perspective view of a stent 100 comprising a plurality of lock beams in a collapsed state in accordance with a representative embodiment. Various aspects and details of the stent 100 described in connection with Fig. 1C are common to those of the stent 100 described above in connection with Figs. 1 A-1B. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0045] In the collapsed state, the closed cell mesh 102 of the stent 100 is compressed to a reduced diameter (r-direction in the cylindrical coordinate system of Fig. 1C) for insertion in a delivery device (not shown). Moreover, the lock beams 104 are also collapsed, having been bent toward the inner portion of the stent, as will be described more fully below. Notably, the sections 106 are not discernable in Fig. 1C having been bent inwardly. As described more fully below, this inward bending of the lock beams 104 usefully allows the diameter (r-direction) of the stent 100 to reach its reduced radius collapsed state. By contrast, and as noted below, if the lock beams 104 were bent outwardly, while a reduced overall diameter would be achieved compared to the stent at a nominal diameter, this would not provide the degree of compactness in the stent 100 for disposition in a delivery device.

[0046] Fig. ID is perspective view of a portion of the stent of Fig. 1C showing the compressible mesh and lock beams in the collapsed state in accordance with a representative embodiment. Various aspects and details of the stent 100 described in connection with Fig. ID are common to those of the stent 100 described above in connection with Figs. 1 A-1C. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0047] Again, as shown more clearly in Fig. ID, the closed cell mesh 102 and the lock beams 104 are collapsed, with the lock beams 104 having been bent toward the inner portion of the stent 100. Notably, the sections 106 are more discernable in Fig. ID having been bent inwardly. As will be appreciated, this inward bending of the lock beams 104 usefully allows the diameter of the stent 100 to reach its reduced radius collapsed state. By contrast, and as noted below, if the lock beams 104 were bent outwardly, while a reduced overall diameter (r-direction in the cylindrical coordinate system of Fig. ID) would be achieved compared to the stent at a nominal diameter, this would not provide the degree of compactness in the stent 100 for disposition in a delivery device.

[0048] Fig. IE is another perspective view of a portion of the stent 100 of Fig. 1C showing the compressible mesh and lock beams in the collapsed state in accordance with a representative embodiment. Various aspects and details of the stent 100 described in connection with Fig. IE are common to those of the stent 100 described above in connection with Figs. 1 A-1D. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0049] The closed cell mesh 102 and the lock beams 104 are collapsed, with the lock beams 104 having been bent toward the inner portion of the stent 100. Notably, the sections 106 are more discernable in Fig. IE having been bent inwardly. As will be appreciated, this inward bending of the lock beams 104 usefully allows the diameter of the stent 100 to reach its reduced radius collapsed state.

[0050] Fig. IF is another perspective view of the stent of Fig. 1C showing the compressible mesh and lock beams in a collapsed state in accordance with a representative embodiment. Various aspects and details of the stent 100 described in connection with Fig. IF are common to those of the stent 100 described above in connection with Figs. 1 A-1E. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0051] As shown, the closed cell mesh 102 and the lock beams 104 are collapsed, with the lock beams 104 having been bent toward the inner portion of the stent 100. Notably, the sections 106 in an inner portion 110 of the collapsed stent 100 can be seen having been bent inwardly. As will be appreciated, this inward bending of the lock beams 104 usefully allows the diameter (r- direction in the cylindrical coordinate system of Fig. IF) of the stent 100 to reach its reduced radius collapsed state.

[0052] As described more fully below, the inward bending of the lock beams 104 (and sections 106 thereof) can be done using a tool prior to or during the initial stages of collapsing the collapsible closed cell mesh 102 for deployment into the delivery device. The tool may be an iris that can reduce in diameter to crimp the stent. On the inner surface of the iris, protrusions are placed in locations aligned with the lock beams 104. These protrusions should be tall enough, such that the ends of the lock beams 104 are pushed radially inward more than the height of the stent struts. In this way, when the stent 100 is crimped a certain amount, the lock beams 104 will slide behind the other struts of the stent 100. As soon as this occurs the protrusions are no longer necessary.

[0053] Alternatively, the crimping of the stent might be carried out using the shape memory effect of a shape memory material, for example Nitinol. The stents nominal shape is first set. Next the temperature is lowered such that the material is martensitic. In this stage the lock beams 104 may be bent inward by any means (i.e. with a special tool or manually), such that they maintain this deformed shape. The stent is then crimped to at least a diameter where the lock beams 104 are behind the other struts of the stent. After this, the temperature may be increased such that the stent attempts to regain its nominal shape. Upon deployment and thus expanded, expansion from crimped diameter, the lock beams 104 will elastically deform back to their original locked position. After deployment via the delivery device, the expansion of the collapsible closed cell mesh 102 causes the sections 106 of the lock beams 104 to return to their location at the nominal diameter with gaps 108 therebetween. Alternatively, after expansion of the collapsible closed cell mesh 102, a tool, such a s a balloon, may be used to bend the lock beams 104 back to return to their location at the nominal diameter with gaps 108 therebetween. [0054] Fig. 2A shows a tangential (top) and radial (bottom) views of a section of collapsible closed cell mesh 202 comprising struts 203 of a stent including lock beams 104 before compression for deployment in accordance with a representative embodiment. Various aspects and details of the section of the stent described in connection with Fig. 2A are common to those of the stent 100 described above in connection with Figs. 1 A-1F. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0055] Notably, the lock beams 204 are disposed across the section of collapsible closed cell mesh 202 with gaps 206 between the lock beams, indicative of the stent’s having a nominal diameter.

[0056] Fig. 2B shows a tangential (top) and radial (bottom) views of a section of a collapsible closed cell mesh 202 comprising struts 203 and including lock beams 204 in a partially collapsed state prior to deployment in a delivery device in accordance with a representative embodiment. Various aspects and details of the section of the stent described in connection with Fig. 2B are common to those of the stent 100 described above in connection with Figs. 1 A-2A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0057] As depicted in Fig. 2B, the section of closed cell mesh 202 comprising struts 203 is crimped to collapse and the lock beams 204 are bent inwardly thereby reducing the areal footprint of the section of the closed cell mesh 202, and reducing the resultant diameter of a stent comprising a plurality of sections of the closed cell mesh 202 for insertion in a delivery device for deployment. Notably, the section of closed cell mesh 202 depicted in Fig. 2B is shown in an intermediate step where the diameter of the stent is less than the nominal diameter, but not small enough to insert into the delivery device. [0058] Fig. 2C shows a tangential (top) and radial (bottom) views of a section of a stent including lock beams in a collapsed state for deployment in accordance with a representative embodiment. Various aspects and details of the section of the stent described in connection with Fig. 2C are common to those of the stent 100 described above in connection with Figs. 1A-2B. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0059] As depicted in Fig. 2C, the section of closed cell mesh 202 comprising struts 203 is crimped to collapse and the lock beams 204 are bent inwardly thereby further reducing the areal footprint of the section of the closed cell mesh 202, and reducing the resultant diameter of a stent comprising a plurality of sections of the closed cell mesh for insertion in a delivery device for deployment. Notably, the section of closed cell mesh 202 comprising struts 203 depicted in Fig. 2C is shown in the final step for deployment where the diameter of the stent is small enough to insert into the delivery device.

[0060] Fig. 2D shows a tangential (top) and radial (bottom) views of a section of a stent including lock beams in a locked state after deployment in accordance with a representative embodiment. Various aspects and details of the section of the stent described in connection with Fig. 2D are common to those of the stent 100 described above in connection with Figs. 1 A-2C. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0061] As shown in Fig. 2D the lock beams 204 are disposed across the section of collapsible closed cell mesh 202 with no gaps 206 between the lock beams 204 and the nearest strut 203, indicative of the stent’s being in a locked state. When the sections of collapsible closed cell mesh 202 that make up the stent are in this locked state, the stent has a minimum diameter such as discussed above.

[0062] Fig. 3 A is a perspective view of a stent 300 comprising a plurality of lock beams 304 in a closed cell mesh 302 comprising struts 303 in accordance with a representative embodiment. Various aspects and details of the section of the stent 300 described in connection with Fig. 3A are common to those of the various representative embodiments described above in connection with Figs. 1 A-2D. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0063] The lock beams 304 are disposed around a circumference of the closed cell mesh 302 tangentially (9 direction in the cylindrical coordinate system of Fig. 1 A) provided added stiffness to the collapsible closed cell mesh in the radial direction (r direction in the cylindrical coordinate system of Fig. 1 A). Notably, and as more clearly shown in Fig. IB, the stent 300 is at a minimum diameter having some elasticity only to expand (+r direction) but not compress (-r direction). As such, at the minimum diameter, there is no gap between the sections of the lock beams 304 and their nearest strut 303 of the closed cell mesh 302.

[0064] As shown, the lock beams 304 comprise sections of circles disposed tangentially around the circumference of the closed cell mesh 302. As alluded to above, when the stent 300 is compressed, the sections of the lock beams 304 contact the nearest strut of the closed cell mesh 302 substantially forming a circle that defines the minimum radius, and the maximum compression, of the closed cell mesh 302, and thus the stent 300.

[0065] The spacing (along the z-direction) of the lock beams 304 is selected to provide a desired degree of stiffness when the stent 300 is compressed to the minimum radius. As will be appreciated, smaller spacing of the lock beams 304 increases the stiffness in the radial direction at each point along the length (z-direction) of the stent 300. Similarly, greater spacing of the lock beams 304 will provide less stiffness in regions between lock beams 304 allowing greater collapse of the closed cell mesh 302 in the regions between the lock beams. As such, and as described above, the selection of the spacing between the lock beams also impacts the stiffness of the stent in the radial direction along the length of the stent.

[0066] Fig. 3B is a perspective view of a portion of the stent 300 of Fig. 3A showing the lock beams 304 positioned to provide a minimum diameter (r-direction of the cylindrical coordinate system of Fig. IB) of the stent 300 in accordance with a representative embodiment. Various aspects and details of the portion of the stent described in connection with Fig. 3B are common to those of the various embodiments described above in connection with Figs. 1 A-3A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0067] The lock beams 304 are disposed around a circumference of the closed cell mesh 302 tangentially (9 direction in the cylindrical coordinate system of Fig. 1 A) provided added stiffness to the collapsible closed cell mesh 302 in the radial direction (r direction in the cylindrical coordinate system of Fig. 3A). Illustratively, once deployed, the stent 300 has the minimum diameter. As alluded to above, in this compressed state, the gaps between the sections 306 of the lock beams and the nearest strut 303 of the closed cell mesh 302 are eliminated, and the stent 300 has a minimum diameter with the lock beams 104 having a substantially circular shape. In this position, which may be referred to as a locked position, the lock beams 304 is adapted to tangentially increase a stiffness of the collapsible closed cell mesh 302 radially (r-direction). (However, as noted above, the stent 300 has some elasticity allowing for an increase of the diameter of the stent should the need arise, and the appearance of the gaps between the sections of the lock beams 304 and the nearest strut 303 of the closed cell mesh 302). Finally, and as described above, the lock beams 304 are adapted to collapse inwardly to an unlocked position when the collapsible closed cell mesh is collapsed, for example for deployment.

[0068] Fig. 4A is a perspective view of a stent 400 comprising a plurality of lock beams 404 in a closed cell mesh 402 comprising struts 403 in accordance with a representative embodiment. [0069] The lock beams 404 are disposed around a circumference of the closed cell mesh 402 tangentially (0 direction in the cylindrical coordinate system of Fig. 4A) provided added stiffness to the collapsible closed cell mesh 402 in the radial direction (r direction in the cylindrical coordinate system of Fig. 4A). Notably, the stent 400 is at a nominal diameter having some elasticity to expand (+r direction) and compress (-r direction), but is not disposed at the minimum radius. As such, at the nominal diameter, the sections 406 of the lock beams 404 are separated from struts 103 by a gap 408, whereas in the locked position, there is no gap between the sections of the lock beams 404 and the struts 403 of the closed cell mesh 402.

[0070] The closed cell mesh 402 is illustratively collapsible, which is useful when compressing the stent 400 for disposition in a delivery device (not shown) and providing some elasticity once deployed. The material selected for the closed cell mesh 402 may be one of the many materials noted above in connection with various representative embodiments. Moreover, and again as noted above, in certain embodiments, shape memory materials may be used for the closed cell mesh enabling deployment in the artery or vein by application of heat so the closed cell mesh expands to its final dimension. Alternatively, the closed cell mesh 402 may be expanded once deployed in-situ using a balloon or other known device.

[0071] The lock beams 404 comprise sections of circles disposed tangentially around the circumference of the closed cell mesh 402. As noted above and described more fully below, when the stent 400 is compressed, the sections of the lock beams contact the nearest strut 403 of the closed cell mesh 402 forming a circle that defines the minimum radius, and the maximum compression, of the closed cell mesh 402, and thus the stent 400. Notably, and as described more fully above, a variety of materials may be used for the lock beams 404.

[0072] The spacing (along the z-direction) of the lock beams 404 is selected to provide a desired degree of stiffness when the stent 400 is compressed to the minimum radius. In the presently described representative embodiment, there are three (3) lock beams 404 along the length of the stent 400. As alluded to above, this greater spacing of the lock beams 404 compared to the lock beams 104 of Fig. 1 A, for example, will provide less stiffness in regions between lock beams 404 allowing greater collapse of the closed cell mesh 402 in the regions between the lock beams. As such, the selection of the spacing between the lock beams also impacts the stiffness of the stent in the radial direction along the length of the stent.

[0073] Among other illustrative benefits, providing a comparatively a larger spacing between lock beam rings as shown reduces the flexural stiffness of the stent 100 along the axial direction (z-direction). This is beneficial when the stent 400 is deployed, for example in curved vessels, or when the vessel the stent 400 is deployed and in undergoes flexure. Just by way of illustration the comparatively increased spacing between the lock beams 104 is beneficial in vessels in the legs during walking or in coronary vessels during the beating of the heart.

[0074] Fig 4B is a perspective view of a stent 400 comprising a plurality of lock beams 404 in a collapsed state in accordance with a representative embodiment. Various aspects and details of the stent 400 described in connection with various representative embodiments in connection with Figs. 1 A-4A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0075] In the collapsed state, the closed cell mesh 402 of the stent 400 is compressed to a reduced diameter (r-direction in the cylindrical coordinate system of Fig. 4B) for insertion in a delivery device (not shown). Moreover, the lock beams 404 are also collapsed, having been bent toward the inner portion of the stent, as will be described more fully below. Notably, the sections are not discernable in Fig. 4C having been bent inwardly. As described more fully below, this inward bending of the lock beams 404 usefully allows the diameter (r-direction) of the stent 400 to reach its reduced radius collapsed state. By contrast, and as noted below, if the lock beams 404 were bent outwardly, while a reduced overall diameter would be achieved compared to the stent at a nominal diameter, this would not provide the degree of compactness in the stent 400 for disposition in a delivery device. [0076] Fig. 4C is a side view of the stent 400 of Fig. 4A showing the lock beams 404 positioned to provide a minimum diameter (r-direction of the cylindrical coordinate system of Fig. 4C) of the stent in accordance with a representative embodiment. Various aspects and details of the portion of the stent described in connection with Fig. 4C are common to those described above in connection with the representative embodiments of Figs. 1 A-4B. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0077] The lock beams 404 are disposed around a circumference of the closed cell mesh 402 tangentially (0 direction in the cylindrical coordinate system of Fig. 4C) provide added stiffness to the collapsible closed cell mesh 402 in the radial direction (r direction in the cylindrical coordinate system of Fig. 4C). The lock beams 404 each comprise a number of sections (not shown in Fig. 4C) with no gaps between the sections of the lock beams and nearest struts 403. As such, in this compressed state, the gaps between the sections of the lock beams reduces and at the minimum diameter the gaps disappear causing the lock beams 104 to have a substantially circular shape. In this position, which may be referred to as a locked position, the lock beams 404 are adapted to tangentially increase a stiffness of the collapsible closed cell mesh 102 radially (r-direction). However, the stent 400 has some elasticity allowing for an increase of the diameter of the stent 400 should the need arise. Illustratively, once deployed, the stent 100 has the nominal diameter providing a degree of resilience. As such, the stent 400 is able to increase its diameter (+r direction) and but not compress (-r direction) further.

[0078] Fig. 5 is a flow-chart of a method 500 for deploying a stent in accordance with a representative embodiment. Various aspects and details of the method 500 are common to those described in connection with representative embodiments of Figs. 1A-4C and 6A-6C. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0079] At 501, the method 500 begins with the collapsible closed cell mesh or collapsible mesh positioned so the stent has a nominal diameter. A section 502 of the stent in this state is shown beneath 501 for clarity.

[0080] At 503, the method 500 comprises with stent including the lock beams being cooled and collapsed. As such, in this representative embodiment, the stent and lock beams comprise a shape memory metal as alluded to above. A section 504 of the stent in this state is shown beneath 503 for clarity.

[0081] At 505, the method 500 comprises crimping the stent including the lock beams to a diameter selected for deployment into a delivery device (e.g., a catheter). A section 506 of the stent in this state is shown beneath 505 for clarity.

[0082] At 507 the temperature is increased so the stent recovers it shape and the locks are in original position.

[0083] At 509 the stent is deployed.

[0084] At 511 the stent is deployed and at a nominal diameter. A section 510 of the stent in this state is shown beneath 511 for clarity.

[0085] Fig. 6A is a perspective view of a compressible mesh stent 600 comprising lock beams in a deployed position adapted to increase radial stiffness of the stent in accordance with a representative embodiment. Various aspects and details of the stent 600 are common to those described in connection with representative embodiments of Figs. 1A-5. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0086] As shown in Fig. 6A, the stent 600 comprises a collapsible mesh 602 and lock beams 604. Each lock beam 604 has a plurality of sections 606 that are adapted to be compressed (see Fig. 6C) so that an angle between each section 606 is comparatively small (e.g., 5°) and expanded so an angle between each section 606 is comparatively large (e.g., 180°). Notably, the stent 600 in Fig. 6A shows the collapsible mesh 602 is a deployed state. In this state, the lock beams 604 are disposed along a circumference of the collapsible mesh 602 tangentially (0 direction in the cylindrical coordinate system of Fig. 6 A) and provide added stiffness to the collapsible mesh 602 in the radial direction (r direction in the cylindrical coordinate system of Fig. 6A).

[0087] Fig. 6B is a side view of the compressible mesh stent 600 of Fig. 6A comprising lock beams 604 in a deployed position adapted to increase radial stiffness of the stent in accordance with a representative embodiment. Various aspects and details of the stent 600 are common to those described in connection with representative embodiments of Figs. 1A-6A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0088] As shown in Fig. 6B, the sections 606 of each of the lock beams 604 are expanded and approach straight lines along their length. In this state, the stent 600 is deployed, such as in a vein or artery.

[0089] Fig. 6C is a perspective view of the compressible mesh stent of Fig. 6A comprising lock beams in a collapsed state for deployment in accordance with a representative embodiment. Various aspects and details of the stent 600 are common to those described in connection with representative embodiments of Figs. 1A-6A. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0090] As shown in Fig. 6C, the stent 600 is compressed to a collapsed state. In this state, the diameter (r-direction in the cylindrical coordinate system of Fig. 6C) of collapsible mesh 602 is reduced such as for deployment via a delivery device. Moreover, the sections (not discernable in Fig. 6C) of the lock beams 604 are folding relative to one another with a comparatively small angle between each section. Once delivered by the delivery device, the collapsible mesh 602 and the sections 606 of the locking beams are expanded to realize the shape of Figs. 6A and 6B. This expansion can be done using memory metal for the collapsible mesh 602 and the lock beams 604, or using a balloon to expand the stent 600.

[0091] Although apparatuses, systems and methods including first and second memory wires are described with reference to several exemplary embodiments, it is understood that the words that have been used are words of description and illustration, rather than words of limitation. Changes may be made within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of additive manufacturing of a medical stent based on a computational modeled outcome prediction in its aspects.

[0092] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of the disclosure described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

[0093] One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term “teachings” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

[0094] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in the present disclosure. As such, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents and shall not be restricted or limited by the foregoing detailed description.

Claims

CLAIMS:

1. A stent (100) comprising: an outer portion comprising a collapsible closed cell mesh (102) adapted to be deployed in a lumen; and a lock beam (604) configured to lock the collapsible closed cell mesh (102), the lock beam (604) being adapted to tangentially increase a stiffness of the collapsible closed cell mesh (102) radially, wherein the lock beam (604) is adapted to collapse to an unlocked position when the collapsible closed cell mesh (102) is collapsed.

2. The stent (100) of claim 1, wherein when the lock beam (604) is locked to a locked position, the stent (100) is at a greatest diameter.

3. The stent (100) of claim 2, wherein in the locked position, the collapsible closed cell mesh (102) is expanded to the greatest diameter and a gap (408) exists between the lock beam (604) and a strut of the collapsible closed cell mesh (102).

4. The stent (100) of claim 3, wherein when a force is applied to the stent (100), the stent (100) partially collapses and the gap (408) between the lock beam (604) and the strut ceases to exist.

5. The stent (100) of claim 4, wherein when the gap (408) between the lock beam (604) and the strut ceases to exist, the stent (100) is at a minimum diameter.

6. The stent (100) of claim 1, wherein the lock beam (604) comprises opposing semicircular elements adapted to collapse in the unlocked position.

7. The stent (100) of claim 5, wherein the lock beam (604) comprises a plurality of the lock beams (104) and disposed along a length of the stent (100).

8. The stent (100) of claim 7, wherein the plurality of lock beams (104) are spaced along the length of the stent (100) and when in the locked position prevent the stent (100) from collapsing to a diameter less than the minimum diameter.

9. The stent (100) of claim 7, wherein the plurality of lock beams (104) are spaced along the length of the stent (100) and a region in the gap (408) between two of the plurality of lock beams (104) is adapted to collapse to a diameter less than the minimum diameter of the locked section (502) of the stent (100).

10. A stent (100) comprising: an outer portion comprising a collapsible mesh (602) adapted to be deployed in a lumen; and a lock beam (604) configured to lock the collapsible mesh (602) tangentially, the lock beam (604) being adapted to increase a stiffness of the collapsible mesh (602) radially, wherein the lock beam (604) comprises a plurality of collapsible sections (106).

11. The stent (100) of claim 10, wherein when the stent (100) is in an open state, the collapsible sections (106) of the lock beam (604) are expanded to form a substantially circular structure.

12. The stent (100) of claim 11, wherein in the open state the collapsible sections (106) have an angle of approximately 180° therebetween.

13. The stent (100) of claim 12, wherein in the open state, the collapsible sections (106) are in a locked position and the stent (100) has a minimum diameter.

14. The stent (100) of claim 10, wherein when the collapsible mesh (602) is in a collapsed state, the collapsible sections (106) are folded to a minimum size.

15. The stent (100) of claim 13, wherein the lock beam (604) comprises a plurality of the sections (106) disposed along a circumference of the stent (100).

16. The stent (100) of claim 15, wherein the plurality of lock beams (104) are spaced along the length of the stent (100) and when in the locked position prevent the stent (100) from collapsing to a diameter less than the minimum diameter.

17. The stent (100) of claim 15, wherein the plurality of sections (106) of the lock beam (604) are spaced along the length of the stent (100) and in a gap (408) between two of the plurality of sections (106) collapse to a diameter less than the minimum diameter.

18. A method (500) of delivering an apparatus, the method (500) comprising: disposing a stent (100) in a lumen, the stent (100) comprising: an outer portion comprising a collapsible mesh (602) adapted to be deployed in a lumen; and a lock beam (604) configured to lock the collapsible mesh (602) radially, wherein the lock beam (604) is adapted to collapse to an unlocked position when the collapsible mesh (602) is collapsed.

19. The method (500) of claim 18, wherein after the lumen is deployed in a body, the method (500) comprises removing the lumen and expanding the lock beam (604) so the stent (100) has a nominal diameter.

20. The method (500) of claim 19, wherein expanding the lock beam (604) comprising expanding struts (103) of the collapsible mesh (602).