Radiopaque stent and catheter marking for enhanced fevar / bevar placement

Abstract

A secondary stent device for endovascular implantation includes a stent and radiopaque (RO) markings. The stent includes a region of interest suitable for anchoring the stent to a branch or fenestration of a primary stent device. The stent is expandable from a compressed state suitable for advancing the secondary stent device through a target anatomy to an expanded state suitable for implantation of the secondary stent device within the target anatomy. The RO markings are on the region of interest so that the region of interest is identified under visualization. When the region of interest is aligned at a location adjacent to the branch or fenestration of the primary stent device, the stent is expanded to anchor to the branch or fenestration.

Description

Radiopaque Stent and Catheter Marking for Enhanced fEVAR / bEVAR PlacementInventors: Thierry H. BENJAMIN, Roger LABRECQUE, and Kenneth FAULKNERPriority Claim

[0001] The present disclosure claims priority to U.S. Provisional Patent Application Serial No. 63 / 583,443 filed September 18, 2023; the disclosure of which is incorporated herewith by reference.Field

[0002] The present disclosure relates to an endovascular stent delivery device having radiopaque markings for enhanced visualization to align a given feature of the stent during placement.Background

[0003] An abdominal aortic aneurysm (AAA) refers to a dilation or bulging in the abdominal aorta wall that weakens the affected area. An aortic dissection refers to a tear in the inner layer of the aorta. Over time, areas affected by AAA can enlarge and burst. Endovascular aneurysm repair (EVAR) is a procedure for repairing aortic aneurysms and dissections in the abdominal aorta that includes implanting a stent or a stent-graft (otherwise referred to as an endograft) within the aorta and / or associated branch arteries. In some scenarios a weakened area may be adjacent to a critical artery, such that, if not otherwise addressed, the placement in the aorta of stents typically used in the EVAR procedure, might block access to such a critical artery. In these scenarios, secondary stenting may be placed to preserve blood flow to these vessels.

[0004] X-ray and fluoroscopy are commonly used to visualize endovascular implants and their associated delivery systems, during both the initial clinical intervention, e.g., for accurate delivery system tracking and device positioning as well as patient follow-up visits (e.g., to assess the performance of the implant and potentially re-intervene). Stent area distinction is particularly critical when existing stents have already been implanted and there is a need to implant a secondary stent. For example, a certain area(s) of the secondary stent may be particularly suited for locking or otherwise attaching the secondary stent to a primary stent in the aorta, while otherareas may be particularly suited for placement within a branching vessel as would be understood by those skilled in the art.Summary

[0005] The present disclosure relates to a secondary stent device for endovascular implantation that includes a stent and radiopaque (RO) markings. The stent includes a region of interest suitable for anchoring the stent to a branch or fenestration of a primary stent device. The stent is expandable from a compressed state suitable for advancing the secondary stent device through a target anatomy to an expanded state suitable for implantation of the secondary stent device within the target anatomy. The RO markings are on the region of interest so that the region of interest is identified under visualization. When the region of interest is aligned at a location adjacent to the branch or fenestration of the primary stent device, the stent is expanded to anchor to the branch or fenestration.

[0006] In an embodiment, the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

[0007] In an embodiment, the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

[0008] In an embodiment, the secondary stent device further comprising a stent cover including material interior to, exterior to, or interwoven with the stent.

[0009] In an embodiment, the stent cover comprises a biocompatible, non-thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

[0010] In an embodiment, the membrane is formed from polytetrafluoroethylene (PTFE).

[0011] In an embodiment, the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater than a second stiffness of thesecond portion, a second flexibility of the second portion being greater than a first flexibility of the first portion and wherein the region of interest of the stent comprising RO markings comprises all or part of the first portion of the stent having the first stiffness.

[0012] In an embodiment, the stent has a portion that automatically flares for placement at the location within or adjacent to a feature of the primary stent device and wherein the region of interest of the stent comprising RO markings comprises all or part of the portion of the stent that automatically flares.

[0013] In an embodiment, the primary stent device comprises a fenestrated stent device and the feature comprises the fenestration and wherein the region of interest of the stent comprising RO markings can be expanded within the fenestration so that the stent is anchored to the fenestration.

[0014] In an embodiment, the primary stent device comprises a branched stent device and the feature comprises the branch and wherein the region of interest of the stent comprising RO markings can be expanded within the branch so that the stent is anchored to the branch.

[0015] In addition, the present disclosure relates to a for endovascular implantation of a secondary stent device. The method includes advancing the secondary stent device through a target anatomy in a compressed state, the secondary stent device including a stent comprising a region of interest suitable for anchoring the stent to a branch or fenestration of a primary stent device, the secondary stent device further including radiopaque (RO) markings on the region of interest so that the region of interest is identified under visualization; aligning the region of interest at a location adjacent to the branch or fenestration of the primary stent device; and expanding the stent to anchor the stent to the branch or fenestration.

[0016] In an embodiment, the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

[0017] In an embodiment, the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

[0018] In an embodiment, the secondary stent device further includes a stent cover including material interior to, exterior to, or interwoven with the stent.

[0019] In an embodiment, the stent cover comprises a biocompatible, non-thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

[0020] In an embodiment, the membrane is formed from polytetrafluoroethylene (PTFE).

[0021] In an embodiment, the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater than a second stiffness of the second portion, a second flexibility of the second portion being greater than a first flexibility of the first portion and wherein the region of interest of the stent comprising RO markings comprises all or part of the first portion of the stent having the first stiffness.

[0022] In an embodiment, the stent has a portion that automatically flares for placement at the location within or adjacent to a feature of the primary stent device and wherein the region of interest of the stent comprising RO markings comprises all or part of the portion of the stent that automatically flares.

[0023] In an embodiment, the primary stent device comprises a fenestrated stent device and the feature comprises the fenestration and wherein the region of interest of the stent comprising RO markings can be expanded within the fenestration so that the stent is anchored to the fenestration.

[0024] In an embodiment, the primary stent device comprises a branched stent device and the feature comprises the branch and wherein the region of interest of the stent comprising RO markings can be expanded within the branch so that the stent is anchored to the branch.

[0025] Furthermore, the present disclosure relates to a stent device for endovascular implantation. The stent device includes a stent comprising a region of interest, the stentconfigured to be expandable from a compressed state suitable for advancing a secondary stent device through a target anatomy to an expanded state suitable for implantation of the secondary stent device within the target anatomy; and radiopaque (RO) markings on an aspect of the stent device so that the region of interest is identified under visualization and, when the region of interest is aligned at a location adjacent to a feature of a further stent, the stent is expanded.

[0026] In an embodiment, the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

[0027] In an embodiment, the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

[0028] In an embodiment, the stent device further comprising a stent cover including material interior to, exterior to, or interwoven with the stent.

[0029] In an embodiment, the stent cover comprises a biocompatible, non-thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

[0030] In an embodiment, the membrane is formed from polytetrafluoroethylene (PTFE).

[0031] In an embodiment, the stent device further comprising a stent cover including material interior to, exterior to, or interwoven with the stent, wherein the RO markings comprise a metal coating selectively applied to a region of the stent cover.

[0032] In an embodiment, the region of the stent cover is adjacent to the region of interest of the stent.

[0033] In an embodiment, the stent device further comprising a delivery catheter carrying the stent in the compressed state as the secondary stent device is advanced through the target anatomy.

[0034] In an embodiment, the RO markings are applied to a region of the catheter adjacent to the region of interest of the stent when the stent is in the compressed state.

[0035] In an embodiment, the RO markings comprise a metal coating selectively applied to the region of the catheter.

[0036] In an embodiment, the RO markings comprise a polymeric band placed on the region of the catheter, the polymeric band including a polymer combined with a radiopaque material.

[0037] In an embodiment, the stent device further comprising a balloon for expanding the stent into the expanded state, wherein the polymeric band is placed on a shaft of the delivery catheter beneath the balloon and the stent is crimped to the shaft over the balloon.

[0038] In an embodiment, the shaft of the delivery catheter is formed with a slot and the polymeric band is placed on the shaft within the slot.

[0039] In an embodiment, the polymer is selected for adhesion to the delivery catheter and the radiopaque material comprises tungsten.

[0040] In an embodiment, the polymeric band is placed on the catheter via fusion, heat, sonication, swaging, solvent, adhesive, pressure, mechanical interlock, radiofrequency welding, chemical bonding, friction, or heat shrink.

[0041] In an embodiment, the stent device further comprising a balloon for expanding the stent into the expanded state.

[0042] In an embodiment, the RO markings are applied to a region of the balloon adjacent to the region of interest of the stent when the stent is in the compressed state.

[0043] In an embodiment, the RO markings comprise a metal coating selectively applied to the region of the balloon.

[0044] In an embodiment, the RO markings comprise a polymeric band placed on the region of the balloon, the polymeric band including a polymer combined with a radiopaque material.

[0045] In an embodiment, the RO markings are applied to a region of the balloon comprising a step, a transition, or a variation in diameter of the balloon.

[0046] In an embodiment, the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater than a second stiffness of the second portion, a second flexibility of the second portion being greater than a first flexibility of the first portion, and wherein the first portion is suitable for anchoring the stent to a branch or fenestration of the further stent.

[0047] In an embodiment, the aspect of the stent device comprising RO markings is adjacent to the first portion of the stent having the first stiffness.

[0048] In an embodiment, the aspect of the stent device comprising RO markings is adjacent to the second portion of the stent having the second flexibility.

[0049] In an embodiment, the stent further includes a third portion transitioning between the first portion and the second portion, wherein the aspect of the stent device comprising RO markings is adjacent to the third portion of the stent.

[0050] In an embodiment, the stent has a portion that automatically flares for placement at the location within or adjacent to the secondary stent device and wherein the aspect of the stent device comprising RO markings is adjacent to the portion of the stent that automatically flares.

[0051] In addition, the present disclosure relates to a stent device for endovascular implantation. The stent device includes a stent comprising a region of interest, wherein the stent is expandablefrom a compressed state suitable for advancing the stent device through a target anatomy to an expanded state suitable for implantation of the stent device within the target anatomy; and radiopaque (RO) markings on the region of interest so that the region of interest is identified under visualization and, when the region of interest is aligned at a location adjacent to a feature of a further stent device, the stent is expanded.

[0052] In an embodiment, the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

[0053] In an embodiment, the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

[0054] In an embodiment, the stent device further comprising a stent cover including material interior to, exterior to, or interwoven with the stent.

[0055] In an embodiment, the stent cover comprises a biocompatible, non-thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

[0056] In an embodiment, the membrane is formed from polytetrafluoroethylene (PTFE).

[0057] In an embodiment, the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater than a second stiffness of the second portion, a second flexibility of the second portion being greater than a first flexibility of the first portion, wherein the first portion is suitable for anchoring the stent to a branch or fenestration of the further stent.

[0058] In an embodiment, the region of interest of the stent comprising RO markings comprises all or part of the first portion of the stent having the first stiffness.

[0059] In an embodiment, the region of interest of the stent comprising RO markings comprises all or part of the second portion of the stent having the second flexibility.

[0060] In an embodiment, the stent further includes a third portion transitioning between the first portion and the second portion and wherein the region of interest of the stent comprising RO markings comprises all or part of the third portion of the stent.

[0061] In an embodiment, the stent has a portion that automatically flares for placement at the location within or adjacent to the further stent device and wherein the region of interest of the stent comprising RO markings comprises all or part of the portion of the stent that automatically flares.

[0062] In an embodiment, the further stent device comprises a fenestrated stent device. The region of interest of the stent can be expanded within a fenestration so that the stent is anchored to the fenestration.

[0063] In an embodiment, the further stent device comprises a branched stent device. The region of interest of the stent can be expanded within a branch so that the stent is anchored to the branch.Brief Description of Drawings

[0064] Fig. la shows a guidewire on which a delivery catheter can be placed according to one example.

[0065] Fig. lb shows a stent (unmarked) mounted to a delivery catheter placed on the guidewire of Fig. la according to one example.

[0066] Fig. 1c shows a marked stent mounted to a delivery catheter placed on the guidewire of Fig. la according to various exemplary embodiments.

[0067] Fig. 2a shows the marked stent of Fig. 1 c during an alignment process and prior to deployment in a fenestration of a primary stent.

[0068] Fig. 2b shows the marked stent of Fig. 2a in an expanded state with the proximal region with enhanced RO qualities expanded within the fenestration so that the marked stent anchors to the fenestration.

[0069] Fig. 3a shows a variable flexibility stent (unmarked) mounted to a delivery catheter placed on a guidewire according to one example.

[0070] Fig. 3b shows a marked variable flexibility stent mounted to the delivery catheter placed on the guidewire of Fig. 3a according to one embodiment.

[0071] Fig. 3c shows a marked variable flexibility stent mounted to the delivery catheter placed on the guidewire of Fig. 3a according to another embodiment.

[0072] Fig. 3d shows a marked variable flexibility stent mounted to the delivery catheter placed on the guidewire of Fig. 3a according to still another embodiment.

[0073] Fig. 4a shows a marked auto-flare stent mounted over a balloon and a delivery catheter (not shown) according to one example.

[0074] Fig. 4b shows the marked auto-flare stent of Fig. 4a expanding.

[0075] Fig. 4c shows the marked auto-flare stent of Fig. 4a further expanding.

[0076] Fig. 4d shows the marked auto-flare stent of Fig. 4a fully expanded and anchored to the fenestration.

[0077] Fig. 4e shows a view of the fully expanded marked auto-flare stent of Fig. 4d anchored to the fenestration with the balloon withdrawn from a perspective within the aorta.

[0078] Fig. 5 shows a view of a bare metal marked stent comprising a first region electroplated with a gold coating and a second region not including the gold coating.

[0079] Fig. 6 shows a cross-sectional view of a covered stent including an inner layer of a stent cover, a gold-coated stent, and an outer layer of the stent cover.

[0080] Fig. 7a shows a stent mounted to a marked delivery catheter placed on a guidewire during an alignment process and prior to deployment in a fenestration of a primary stent.

[0081] Fig. 7b shows the stent of Fig. 7a in an expanded state with the proximal region expanded within the fenestration so that the stent anchors to the fenestration.Detailed Description

[0082] The present disclosure may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present disclosure relates to systems and methods for identifying one or more particular regions or features of a stent for endovascular and vascular interventions.

[0083] The exemplary embodiments describe a stent delivery system having selectively enhanced radiopaque (RO) qualities enabling a user to distinguish between different features of the stent to more accurately determine a position of a particular feature of the stent when the stent is inserted to a target site within the patient’s body. In particular, the stent delivery system with RO qualities according to these exemplary embodiments may comprise a bridging stent (e.g., a secondary stent), that is configured to be deployed in a particular relation to a primary stent that was previously implanted in the patient.

[0084] For example, the primary stent may have branches or fenestrations to which it may be desired to anchor the bridging stent. A bridging stent according to various exemplary embodiments described herein has a region, e.g., a proximal region, configured to be attached to a primary stent and this region of the bridging stent according to these embodiments isconfigured to be identified when within the patient’s body under visualization based on the selectively enhanced RO qualities of selected portions of the stent delivery system and / or selectively enhanced RO qualities of selected portions of the bridging stent itself.

[0085] As would be understood by those skilled in the art, X-ray and fluoroscopy are commonly used to visualize endovascular implants and their associated delivery systems during initial clinical intervention for accurate delivery system tracking and device positioning as well as during patient follow-up visits to visualize the implant, assess its performance, and re-intervene if necessary. Some current stent delivery systems include radiopaque (RO) markers (e.g., on a distal portion of the catheter (e.g., at the portions of the catheter containing the ends of the stent) to facilitate identification of the stent position under visualization. These RO markers are configured to allow precise tracking and placement of the device as it is positioned relative to a target site within the patient’s body (e.g., a lesion) to facilitate accurate placement of the stent.

[0086] However, these prior methods have generally permitted only the ends of the stent to be identified without facilitating visual identification of other regions of the stent. Further, these methods limit the visualization of the stent to the pre-deployment and deployment stages, e.g., before the catheter has been withdrawn, and do not provide high selective stent radiopacity postdeployment. Secondary (post-deployment) aspects of the procedure include but are not limited to accurate post dilation, flaring, and overlapping additional stent(s), as well as ensuring proper placement has been maintained in patient follow-up at later times.

[0087] Other current stent delivery systems include RO markings on the stents themselves, e.g., bare metal stents coated with noble metals on the ends of the stent. However, these RO markings have generally not identified selected regions of a stent between the ends of the stent. Such markers generally use swaged marker bands on a catheter to identify the ends of a stent or to use gold or press fit markers on the actual stent itself. However, swaged marker bands generally increase the profile of the device and may damage the catheter, the stent, or a balloon if, for example, the stent is improperly crimped thereover.

[0088] Stent area distinction is particularly critical when existing stent-grafts have already been implanted and there is a need for secondary stenting (during, e.g., FEVAR, BEVAR, etc.), where a bridging (secondary) stent is to be attached to or placed adjacent to a primary stent that was previously implanted in the aorta. According to the current state of the art, a delivery system for a bridging stent can include a delivery catheter for delivering the stent to the target location in the patient’s body in a compressed state, e.g., prior to expansion at the target location. The bridging stent is generally configured to be placed so that a portion of the stent can be expanded within the branch or fenestration of the primary stent. In some scenarios, a balloon may be used for expanding the stent. As would be understood by those skilled in the art, the stent may be a bare metal stent that is covered or uncovered.

[0089] In some aspects of these exemplary embodiments, RO markings may be applied to a proximal portion of the bridging stent, e.g., a region configured for deployment within a branch or fenestration of a primary stent. These RO markings may be applied as a coating, a polymeric band, or in other ways that will be described in greater detail below.

[0090] Fig. la shows a guidewire 100 on which a delivery catheter can be placed according to an exemplary embodiment. Fig. lb shows a stent 101 (unmarked) mounted to a delivery catheter placed on the guidewire 100 of Fig. la according to one example. In this example, the stent 101 is mounted to the outside of the delivery catheter. The stent 101 extends from a proximal end 102 to a distal end 103. It should be understood that the body of the delivery catheter in this example does not have RO qualities and thus is not shown in Fig. lb. RO markings are added to the delivery catheter to indicate the boundaries of the body of the delivery catheter. The delivery catheter includes a proximal marking 104 at a portion of the delivery catheter which, when the stent 101 is received on / in the delivery catheter in a desired location, is proximal of a location of the proximal end 102 of the stent 101 and a distal marking 105 which, when the stent 101 is in the desired location, is distal of the distal end 103 of the stent 101.

[0091] Fig. 1c shows a marked stent 106 mounted to a delivery catheter placed on the guidewire 100 of Fig. la according to various exemplary embodiments. The marked stent 106 includes the stent 101 of Fig. lb having a proximal region 107 comprising RO markings 110 for enhancedvisualization. In this example, the proximal region 107 extends from the proximal end 102 of the stent 101 to a location 108 along the stent 101. A distal region 109 that is not marked with enhanced RO qualities extends from the location 108 to the distal end 103 of the stent 101.

[0092] Fig. 2a shows the marked stent 106 of Fig. 1c during an alignment process and prior to deployment in a fenestration 121 of a primary stent 120. In this example, the primary stent 120 is a fenestrated endograft. The marked stent 106 is guided under visualization in a collapsed state to a desired position in which the proximal region 107 with RO markings 110 is positioned within the fenestration 121.

[0093] Fig. 2b shows the marked stent 106 of Fig. 2a in an expanded state with the proximal region 107 with enhanced RO qualities expanded within the fenestration 121 so that the marked stent 106 anchors to the fenestration 121.

[0094] In some aspects of these exemplary embodiments, RO markings may be applied to different regions of the bridging stent. In one example, the bridging stent may have a variable flexibility, e.g., a strong or stiff portion of the stent configured to lock to the primary stent (e.g., into a fenestration or branch) and a flexible portion configured to better conform to contours of a target vessel. Some variable flexibility stents may further include a transition region between the strong / stiff portion and the flexible portion. Some variable flexibility stents may be balloonexpandable while others may be self-expanding or may be expanded by other means. Such variable flexibility stents require the ability to identify the portion of the stent configured for locking into the fenestration or branch of the primary stent (e.g., the strong portion) as contrasted to a portion or portions of the stent that is (are) flexible to facilitate insertion into and residence within the target vessel.

[0095] Fig. 3a shows a variable flexibility stent 201 (unmarked) mounted to a delivery catheter placed on a guidewire 200 according to one example. The stent 201 extends from a proximal end 202 to a distal end 203. Similar to Figs. Ib-c, the body of the delivery catheter does not have RO qualities and is thus not shown in Fig. 3a or the following Figs. 3b-d described below. The delivery catheter has a proximal marking 204 which, when the stent 201 is at a desired locationwithin / on the delivery catheter, is proximal of the proximal end 202 of the stent 201 and a distal marking 205 which, when the stent 201 is in the desired location, is distal to the distal end 203 of the stent 201.

[0096] The stent 201 may include a stiff proximal region 206 and a flexible distal region 208, as shown in this example. The stiff region 206 in this embodiment is a proximal-most region of the stent 201. The flexible region 208 of this embodiment is a distal-most region of the stent 201. The stiff region 206 has a distal-most ring element 207 adjacent to the flexible region 208. It is noted that, in other embodiments, the stent may include a transition region, e.g., in a location along the stent 201 similar to the location of the ring element 207.

[0097] Fig. 3b shows a marked variable flexibility stent 209 mounted to the delivery catheter placed on the guidewire 200 of Fig. 3a according to one embodiment. The marked stent 209 includes the stent 201 of Fig. 3a with the stiff region 206 comprising RO markings 210 for enhanced visualization. The flexible region 208 of this embodiment is unmarked.

[0098] Fig. 3c shows a marked variable flexibility stent 211 mounted to the delivery catheter placed on the guidewire 200 of Fig. 3a according to another embodiment. The marked stent 211 includes the stent 201 of Fig. 3a with the ring element 207 of the stiff region 206 comprising RO markings 212 for enhanced visualization. The remained of the stiff region 206 other than the ring element 207 and the flexible region 208 of this embodiment are unmarked.

[0099] Fig. 3d shows a marked variable flexibility stent 213 mounted to the delivery catheter placed on the guidewire 200 of Fig. 3a according to still another embodiment. The marked stent 213 includes the stent 201 of Fig. 3a with the flexible region 208 comprising RO markings 214 for enhanced visualization. The stiff region 206 in this embodiment is unmarked.

[0100] In another example, the bridging stent has a region that automatically flares to a greater degree than other regions of the stent. The auto-flare region may be used to, e.g., lock into a fenestration of a primary stent. Similar to the variable flexibility stents, this embodiment includes markers to facilitate the identification of the auto-flare portion of the stent to facilitateaccurate locking of this stent into the fenestration of a primary stent. When the auto-flare region is marked, a user (e.g., operating physician) can then visually identify the auto-flare region so this region may be located as desired within, e.g., a fenestration or branch of a primary stent, and deployed (expanded) at the proper location.

[0101] Fig. 4a shows a marked auto-flare stent 300 mounted over a balloon 310 and a delivery catheter (not shown) in a compressed state according to one example. The stent 300 extends from a proximal end 301 to a distal end 302. The stent 300 comprises a first region 303, a second region 304 and a third region 305. The first region 303 and second region 304 of this embodiment are configured so that, as the balloon 310 expands, expanding the stent 300, the first and second regions 303, 304 flare, as will be further described below.

[0102] In this example, the first region 303 and the second region 304 each comprise a single ring while the third region 305 comprises three rings. In this embodiment, the first region 303 is a proximal-most region of the stent 300 and the second region 304 is between the first region 303 and the third region 305. The third region 305 in this embodiment is a distal-most region of the stent 300. The first and second regions 303 of the stent 300 are configured to be positioned within and / or adjacent to a fenestration 311 of a primary stent when the stent 300 is expanded.

[0103] As will be described in further detail below with regard to Figs. 4b-e, as the stent 300 is expanded, the first and second regions 303, 304 flare to curve toward one another and form crowns that lock onto the fenestration 311. According to the present embodiments, the first and second regions 303, 304 are marked with enhanced RO properties to facilitate the placement of the stent 300. It should be understood that the stent 300 is designed so that, as the stent 300 is expanded, the first and second regions 303, 304 are automatically aligned wi thin / adjacent to the fenestration 311. Thus, in the compressed state shown in Fig. 4a, the fenestration 311 is not required to be lined up perfectly between the first and second regions 303, 304. In this example, the fenestration 311 is adjacent to the second region 304.

[0104] Fig. 4b shows the stent 300 of Fig. 4a expanding. The first region 303 and second region 304 have not yet flared. Fig. 4c shows the stent 300 of Fig. 4a further expanding. The firstregion 303 is flaring to form crowns 306 and the second region 304 is flaring to form crowns 307. The crowns 307 of the second region 304 are wrapping around the fenestration 311 and, as the stent 300 further expands, will pull the first region 303 toward the fenestration 311. Fig. 4d shows the stent 300 of Fig. 4a fully expanded and anchored to the fenestration 311. The crowns 306, 307 of the first and second regions 303, 304 have wrapped around the fenestration 311 to anchor the stent 300 within the fenestration. Fig. 4e shows a view of the fully expanded marked auto-flare stent of Fig. 4d anchored to the fenestration 311 with the balloon withdrawn from a perspective within the aorta.

[0105] According to these exemplary embodiments, the second region 304 and / or third region 305 of the stent 300 can be marked with enhanced RO markings so that these regions can be visually identified during deployment.

[0106] In still another example, the stent may be self-expanding. The self-expanding stent can be formed of shape memory materials, e.g., Nitinol. The self-expanding stent can be designed similarly to the previously described embodiments, e g., including a uniform structure, variable flexibility, flared design, etc.

[0107] As would be understood by those skilled in the art, to visualize a component via X- ray / fluoroscopy, the electron density of the component has to be greater than the surrounding tissue, be it soft tissue (skin, muscle, organ), or hard tissue (bone). Most metals show high electron density, and therefore are naturally radiopaque.

[0108] In some aspects of these exemplary embodiments, portions of the stent can be coated with a noble metal with a high electron density to provide the enhanced RO properties. The coating, which may be applied via electroplating, vapor deposition, or any other known method to one or more selected regions of the stent, may comprise, for example, gold, platinum, or another noble metal with a high electron density. In other aspects of these exemplary embodiments, if a covered stent is used, the stent cover may be coated with a similar material to achieve the enhanced RO properties. In other aspects of these exemplary embodiments, other components of the stent delivery system, e.g., the delivery catheter, or the balloon may includebe a similar coating on selected portions to achieve the same enhanced RO properties positioned to identify target portions of the stent.

[0109] In some aspects, the coating is applied to the bare metal stent. In one example, a bare metal stent is composed of stainless steel and electroplated with a 24kt Gold (99.9%) layer in one or more selected regions. The metal coating may be selectively applied circumferentially or partially circumferentially to any section of the stent to aid in alignment of the stent under visualization in the same manner described above. The gold or platinum coating layer may be selectively atomically bonded circumferentially onto the stent strut inner and outer surface. As would be understood by those skilled in the art, the thickness of the coating may be selected to provide a desired degree of visualization.

[0110] Fig. 5 shows a view of a bare metal marked stent 400 comprising a first region 401 electroplated with a gold coating and a second region 402 not including the gold coating. The stent 400 may correspond to any of the previously discussed marked stents, e.g., marked stents 106, 209, 211, 213, 300.

[0111] In some aspects, the bare metal marked stent can be uncovered. In other aspects, the bare metal marked stent can be covered. According to one aspect of these exemplary embodiments, the stent can be covered on both sides.

[0112] In these embodiments, the coated stent is subsequently covered on both sides by a biocompatible, non-thrombogenic membrane. In one example, the stent cover is formed of polytetrafluoroethylene (PTFE). The stent cover may also be formed of a non-thrombogenic material other than PTFE. The PTFE covered stent design allows the selectively applied gold or platinum plated coating layer to be encapsulated between stent struts and PTFE-covered inner and outer layers. This design minimizes direct contact of the gold or platinum plated layer to the vessel intima. In terms of gold or platinum coating flaking due to material delamination, the PTFE cover will also prevent coating particulates from flowing into the vessel lumen, either acutely or over time.

[0113] Fig. 6 shows a cross-sectional view of a covered marked stent 500 including an inner layer 501 of a stent cover, a gold-coated stent 502, and an outer layer 503 of the stent cover. The stent 502 is encapsulated between the inner layer 501 and the outer layer 503 of the stent cover.

[0114] In another aspect of these exemplary embodiments, the stent cover may be marked in any of the manners described so that regions of interest on the stent can be identified. For example, the stent cover may be marked at locations adjacent to any stent regions that are desired to be visually identified.

[0115] In other aspects of these exemplary embodiments, other components of the stent delivery device, e.g., the delivery catheter or the balloon, may be marked so that corresponding regions of interest of the stent may be identified based on the known spatial relationship between the stent and the stent delivery device. The catheter or balloon may be marked, for example, at locations that are adjacent to these selected stent regions when the stent is in the collapsed state prior to expansion within the target vessel. In certain circumstances, there may be a perceived benefit to having an RO alignment feature associated with the catheter / balloon and not with the stent itself. This may be due to the perception that long term RO identifying a stent region on the implant may obscure visibility for future procedures, may lead to unwarranted complaints and / or may have the potential to lead to artifacts on MR imaging, etc. Any combination of the aforementioned RO marking techniques may be used for marking the catheter and / or balloon.

[0116] Fig. 7a shows an unmarked stent 606 mounted to a marked delivery catheter 600 placed on a guidewire 610 during an alignment process and prior to deployment in a fenestration 121 of a primary stent 120. The stent 606 extends from a proximal end 607 to a distal end 608. The marked delivery catheter 600 has a first region 603 having a first end 604 and a second end 605, the first region 603 being adjacent to a proximal region 609 of the stent 606 (the proximal region 609 of the stent is mounted over the first region 603 of the catheter 600) and comprising RO markings for enhanced visualization. The catheter 600 further includes a proximal RO marking 601 proximal to the proximal end 607 of the stent 606 and a distal RO marking 602 distal to the distal end 608 of the stent 606. The remainder of the catheter 600 other than the first region 603, the proximal RO marking 601 and the distal RO marking 602 is not marked with enhanced ROqualities. In this example, the primary stent 120 is a fenestrated endograft. The stent 606 is guided under visualization in a collapsed state so that the proximal region 609 mounted over the first region 603 of the catheter 600 with RO markings is positioned within the fenestration 121.

[0117] Fig. 7b shows the stent 606 of Fig. 7a in an expanded state with the proximal region 609 expanded within the fenestration 121 so that the stent 606 anchors to the fenestration 121. The catheter 600 includes the first region 603 with RO markings can then be withdrawn, leaving the stent 606 in place.

[0118] In another aspect of these exemplary embodiments, a polymeric marker band having RO qualities can be applied to one or more components of the stent delivery device. The polymeric marker band can be formed by combining a given polymer with a radiopaque material such as tungsten at an appropriate loading as would be understood by those skilled in the art. The RO markings of first region 603 of the catheter 600 shown in Figs. 7a-b can comprise the polymeric band according to the present embodiments.

[0119] In some aspects, the polymeric band can be applied to the delivery catheter. The polymer can be selected to optimize adhesion to the catheter shaft. As balloon catheters are generally built, the catheter shaft can be drawn down or molded to reduce profile for balloon attachment. In one embodiment, the polymeric marker band is placed on the drawn down / molded catheter shaft in a location underneath the balloon and stent. This polymeric marker band may be fused to the shaft to minimize or eliminate an increase in profile and the stent may be crimped over it. The polymeric marker band will be positioned at a specific location selected to identify a selected region of the stent, e.g., a stiff portion of the stent, a flexible portion of the stent or a transition region of the stent. When the stent is loaded onto the balloon and crimped, it will be positioned in such a way that will accurately identify the intended region and provide a feature that allows for accurate deployment of the stent (e.g., in a fenestration of a primary stent).

[0120] In alternative embodiments, the polymeric band can be chemically bonded, printed, press fit, glued, or attached by any other means under the balloon of a stent delivery catheter in a manner that crimping of the stent will not damage the catheter shaft, balloon, or stent. Differentprocesses may be used to apply the marker band (heat, sonication, swaging, solvent, adhesive, pressure, mechanical interlock, RF welding, chemical bonding, friction, heat shrink) as would be understood by those skilled in the art. This RO marker is positioned in a way that will provide information to the user facilitating accurate placement of a stent in a fenestration or branch of a primary stent, in a desired portion of a target vessel, or in any other desired location.

[0121] In another embodiment, the polymeric band can be placed on any component of the stent delivery device to identify a feature on the balloon. For example, it may be desirable to identify a step, a transition, or a variation in diameter of the balloon.

[0122] The exemplary embodiments described above can be applied in a variety of stenting procedures, for example, in the aorta and its branches. The aorta is the largest blood vessel in the human body, carrying blood away from the heart, extending briefly towards the head, curving downward toward the abdomen, and extending through the abdomen before branching into the iliac arteries that provide blood to the pelvic region. The aorta has branches / vessels extending therefrom and it is critical that blood flow be maintained through the aorta and its branches.

[0123] An abdominal aortic aneurysm (AAA) refers to a dilation or bulging in the abdominal aorta wall that weakens the affected area. An aortic dissection refers to a tear in the inner layer of the aorta. Over time, areas showing these conditions can enlarge and / or burst. Endovascular aneurysm repair (EVAR) is a procedure for repairing aortic aneurysms and dissections in the abdominal aorta that includes implanting a stent-graft (otherwise referred to as an endograft) in the aorta. Thoracic EVAR (TEVAR) is a procedure for repairing aortic aneurysms in the thorax (thoracic aortic aneurysms (TAA)). In some scenarios the weakened area may be adjacent to a critical artery, such that a typical endograft used for EVAR / TEVAR procedures would, if placed over this weakened area, block access to the artery. Related procedures have been developed to provide access to these arteries, including branched EVAR (BEVAR), fenestrated EVAR (FEVAR), chimney (or snorkel) EVAR (CHEVAR), kissing stents, covered endovascular repair of aortic bifurcation (CERAB) and other procedures.

[0124] As described above, a stent delivery system generally comprises a guidewire, a delivery catheter, and a stent that can transition from a compressed state to an expanded state. As would be understood by those skilled in the art, a guidewire for the catheter may be introduced to the patient anatomy via, for example, the iliac or femoral artery and advanced to the aorta. A catheter carrying the stent in the compressed state is advanced over the guidewire to the target site where the aneurysm / dissection is located. The catheter may be guided to the target site using a vision system such as, for example, X-ray or fluoroscopy. Once it has been positioned at the target site as desired, the stent may be expanded in any of a variety of known ways.

[0125] For example, if the stent is compressed within the catheter, the stent may be expanded by slowly withdrawing the catheter relative to the stent so that the stent may expand (e.g., under a natural bias or through the action of shape memory materials such as Nitinol as the constraint of the catheter is withdrawn proximally to expose the stent, under the influence of body temperatures, etc.). In another example, the stent may be compressed over a deflated balloon attached to the outside of the catheter shaft. When the stent has been positioned as desired at the target site, the balloon is inflated to expand the stent. After the stent has been expanded as desired to hold the artery walls in a desired spatial configuration, the balloon is deflated and the guidewire and catheter are withdrawn proximally from the stent leaving the stent in position to seal and / or reinforce the target area of the artery (e.g., an area including and surrounding the aneurysm) so that blood may flow through the endograft while isolating the aneurysm from the pressure of the blood.

[0126] An endograft generally comprises a tube (e.g., graft) supported by a mesh (e.g., stent). The graft can be formed from a synthetic material, e.g., polytetrafluoroethylene (PTFE), that is biocompatible and non-thrombogenic (i.e., will not cause clotting) while the stent is formed as a metallic skeleton that forms a scaffold to hold the walls of the target blood vessel open to a desired extent. As would be understood by those skilled in the art, the stent may be formed from bare metal or may be coated with any desired material. The graft part and the stent part may be coterminous, or the stent may extend proximally and / or distally beyond the proximal and distal ends of the graft. The endograft may also include stent portions for anchoring the endograft at a desired location within the target blood vessel.

[0127] An exemplary EVAR procedure may comprise implanting an endograft as described above in a lower section of the abdominal aorta (e.g., above the aortic bifurcation). Aneurysms in this area may be located in or adjacent to the iliac arteries below the aortic bifurcation. When this occurs a bifurcated endograft may be used, which includes two nubs / branches to support extensions into both iliac arteries.

[0128] Some aneurysms may be located in an upper section of the abdominal aorta, e.g., in or adjacent to the renal arteries. In fenestrated EVAR (FEVAR), the primary stent-graft includes fenestrations (holes) in the walls of the graft which positioned so that the stent may be implanted with the fenestrations aligned with openings from the aorta to target branch arteries so that blood may flow unimpeded into these branch arteries and / or so that secondary stents may be placed in the fenestrations to extend into and preserve blood flow into these branch vessels.

[0129] A primary stent-graft may be customized to the anatomy of the patient (e.g., based on earlier scans of the patient) with fenestrations configured so that they may be aligned with the branches. After a primary stent-graft has been positioned as desired, one or more secondary covered stents may then be advanced through the fenestrations in the primary stent-graft into the target branch arteries and anchored to the fenestrations, e.g., expanded at a desired position within the fenestration so that a strong connection (e.g., a lock) can be made anchoring the secondary stent to the primary stent as desired. FEVAR can be used to deploy secondary stents in, e.g., the renal arteries, the superior mesenteric artery (SMA), the celiac artery or other vessels.

[0130] In branched EVAR (BEVAR), the primary stent-graft includes branch portals in the walls of the graft through which secondary stents can be placed into branching vessels. The BEVAR procedure may be performed similarly to the FEVAR procedure. One or more secondary covered stents can be advanced through the branch portals in the primary stent-graft and anchored to the branches, e.g., expanded at a proper position within the branch so that a strong connection (e.g., a lock) is made between each secondary stent and the primary stent. BEVAR can be used to deploy secondary stents in, e.g., the renal arteries, the superior mesenteric artery (SMA), the celiac artery or other vessels as would be understood by those skilled in the art.

[0131] In other procedures (e.g., chimney / snorkel EVAR (CHEVAR), sandwich EVAR), secondary covered stents may be implanted on the outside of the primary endograft. In some procedures, the delivery catheter for a secondary stent is guided outside the primary stent and the secondary stent is expanded so that the secondary stent is implanted in the aorta / branch with at least a portion of the secondary stent in abutting contact with the primary stent. In other procedures, kissing stents may be deployed in a parallel fashion at a vessel junction that is not in contact with a primary stent / endograft. In other procedures, covered stents may be deployed in a parallel fashion within the end of a larger primary stent or endograft while performing a Covered Endovascular Repair of Aortic Bifurcation (CERAB).

[0132] As described above, many different types of endografts and, in some cases, multiple endografts may be used to treat aortic aneurysms. The placement of these endografts is critical for preserving blood flow through the aorta and to arteries extending off the aorta.

[0133] The exemplary embodiments described above including selectively enhanced RO markings can be applied in secondary stenting applications for arteries / branches including: the iliac arteries; the femoral arteries; the renal arteries; the superior mesenteric arteries; the celiac trunk; the hypogastric (internal iliac) off of the common iliac; the right subclavian or right common carotid arteries off of the innominate (brachiocephalic artery); and arteries in the thoracic portion of the aorta including the Innominate (brachiocephalic), Left common Carotid and Left Subclavian arteries. It should be understood that the exemplary embodiments are not limited to these arteries / branches, and many other smaller branches can be stented according to these exemplary embodiments.

[0134] In other embodiments, the secondary stent is not placed in a fenestration / branch yet still requires accuracy during placement, e.g., in Chimney / Snorkel procedures (ChEVAR), ostial placement, Kissing stents or in Covered Endovascular Repair of Aortic Bifurcation (CERAB). These stents may not have variable flexibility or auto-flaring, yet a given region of the stent may require identification for accurate placement.

[0135] It will be appreciated by those skilled in the art that changes may be made to the embodiments described above without departing from the inventive concept thereof. It should further be appreciated that structural features and methods associated with one of the embodiments can be incorporated into other embodiments. It is understood, therefore, that this invention is not limited to the particular embodiment disclosed, but rather modifications are also covered within the scope of the present invention as defined by the appended claims.

Claims

What is claimed is:

1. A secondary stent device for endovascular implantation, comprising: a stent comprising a region of interest suitable for anchoring the stent to a branch or fenestration of a primary stent device, wherein the stent is expandable from a compressed state suitable for advancing the secondary stent device through a target anatomy to an expanded state suitable for implantation of the secondary stent device within the target anatomy; and radiopaque (RO) markings on the region of interest so that the region of interest is identified under visualization and, when the region of interest is aligned at a location adjacent to the branch or fenestration of the primary stent device, the stent is expanded to anchor to the branch or fenestration.

2. The secondary stent device of claim 1, wherein the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

3. The secondary stent device of claim 2, wherein the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

4. The secondary stent device of claim 2, further comprising: a stent cover including material interior to, exterior to, or interwoven with the stent.

5. The secondary stent device of claim 4, wherein the stent cover comprises a biocompatible, non-thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

6. The secondary stent device of claim 5, wherein the membrane is formed from polytetrafluoroethylene (PTFE).

7. The secondary stent device of claim 1, wherein the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater thana second stiffness of the second portion, a second flexibility of the second portion being greater than a first flexibility of the first portion and wherein the region of interest of the stent comprising RO markings comprises all or part of the first portion of the stent having the first stiffness.

8. The secondary stent device of claim 1, wherein the stent has a portion that automatically flares for placement at the location within or adjacent to a feature of the primary stent device and wherein the region of interest of the stent comprising RO markings comprises all or part of the portion of the stent that automatically flares.

9. The secondary stent device of claim 8, wherein the primary stent device comprises a fenestrated stent device and the feature comprises the fenestration and wherein the region of interest of the stent comprising RO markings can be expanded within the fenestration so that the stent is anchored to the fenestration.

10. The secondary stent device of claim 8, wherein the primary stent device comprises a branched stent device and the feature comprises the branch and wherein the region of interest of the stent comprising RO markings can be expanded within the branch so that the stent is anchored to the branch.

11. A method for endovascular implantation of a secondary stent device, comprising: advancing the secondary stent device through a target anatomy in a compressed state, the secondary stent device including a stent comprising a region of interest suitable for anchoring the stent to a branch or fenestration of a primary stent device, the secondary stent device further including radiopaque (RO) markings on the region of interest so that the region of interest is identified under visualization; aligning the region of interest at a location adjacent to the branch or fenestration of the primary stent device; and expanding the stent to anchor the stent to the branch or fenestration.

12. The method of claim 11, wherein the RO markings comprise a metal coating selectively applied to at least one selected ring of the stent.

13. The method of claim 12, wherein the metal coating comprises gold or platinum selectively applied by electroplating to the at least one selected ring with a specified coating layer thickness.

14. The method of claim 12, wherein the secondary stent device further includes a stent cover including material interior to, exterior to, or interwoven with the stent.

15. The method of claim 14, wherein the stent cover comprises a biocompatible, non- thrombogenic membrane including an inner layer and an outer layer encapsulating the stent and the metal coating.

16. The method of claim 15, wherein the membrane is formed from polytetrafluoroethylene (PTFE).

17. The method of claim 11, wherein the stent has variable flexibility and includes a first portion and a second portion, a first stiffness of the first portion being greater than a second stiffness of the second portion, a second flexibility of the second portion being greater than a first flexibility of the first portion and wherein the region of interest of the stent comprising RO markings comprises all or part of the first portion of the stent having the first stiffness.

18. The method of claim 11, wherein the stent has a portion that automatically flares for placement at the location within or adjacent to a feature of the primary stent device and wherein the region of interest of the stent comprising RO markings comprises all or part of the portion of the stent that automatically flares.

19. The method of claim 18, wherein the primary stent device comprises a fenestrated stent device and the feature comprises the fenestration and wherein the region of interest of the stentcomprising RO markings can be expanded within the fenestration so that the stent is anchored to the fenestration.

20. The method of claim 18, wherein the primary stent device comprises a branched stent device and the feature comprises the branch and wherein the region of interest of the stent comprising RO markings can be expanded within the branch so that the stent is anchored to the branch.

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