Expandable sleeve stent and its preparation method

Abstract

An expandable stent with a sleeve comprises: a stent and a sleeve. The stent comprises a tubular body having first and second axial ends; a lattice outer wall; and at least two arms, wherein when the tubular body radially expands from a crimped position to an expanded state, the arms radially protrude from the lattice outer wall, and the free end of each arm is radially movable relative to the adjacent lattice outer wall. The sleeve: (a) extends from the first axial end of the tubular body and circumferentially covers at least a portion of the radially outer surface of the lattice outer wall between the free ends of the arms and the first axial end of the tubular body; (b) bridges the space between the portion of the lattice outer wall adjacent to the arm and the free ends of the arm; and (c) is fixed to any of the following: (1) the arm; or (2) the tubular body in the vicinity between the free ends of the arms and the second axial end of the tubular body. When the tubular body radially expands toward the expanded state and the arms subsequently radially protrude from the lattice outer wall, the portion of the sleeve bridging the lattice outer wall and the arms opens radially outward.

Description

Background Art

[0001] The present invention relates to an expandable stent with a sleeve. More specifically, the present invention relates to an expandable stent with a sleeve, comprising: (1) a tubular body comprising a lattice outer wall and arms, wherein the arms radially protrude from the lattice outer wall when the tubular body radially expands; and (2) a sleeve extending circumferentially along a portion of the lattice outer wall and the arms. More specifically, the present invention relates to an expandable stent with a sleeve in Yizhuang, comprising radially expandable arms and sleeves, wherein the sleeves bridge the free ends of the arms and the adjacent portions of the lattice outer wall, such that when the arms radially extend from the lattice outer wall, the bridging portions of the sleeves radially open. The present invention also relates to an expandable stent with a sleeve, wherein the sleeves define radially outwardly extending protrusions that accommodate radially protruding stent arms therein when the stent radially expands. Further, the present invention also relates to a method for manufacturing an expandable stent with a sleeve.

[0002] Stents are used to treat aneurysms and to secure and support replacement valves. When secured in a patient's vasculature, the radially outer surface of the stent preferably seals against the wall of the vasculature. Failure to form such a seal can result in blood flowing between the radially outer surface of the stent and the wall of the vasculature, which in turn can exert pressure on the aneurysm or cause paravalvular leakage. To improve the seal between the stent and the wall of the vasculature, various balloons, sleeves, skirts, or structures have been added to stents. These additional features protrude radially beyond the radially outer surface of the stent. For example:

[0003] US 2006 / 0271172 “Minimally Invasive Aortic Valve Replacement” describes a stent having a deformable ring on its radially outer surface.

[0004] US2006 / 0292206 “Device and method for treating vascular aneurysms” and EP2815723 “Collapsible and expandable artificial heart valve sleeve design and complementary technology applications” describe a stent having an expandable material on its radial outer surface.

[0005] US 2009 / 0112305 “Stent graft prosthesis” and US 2014 / 0058436 “Blood flow interruption device and method for treating vascular defects” describe a stent having a radially expandable sleeve surrounding the radially outer surface of the stent.

[0006] US2004 / 0044358 "Methods and devices for treating aneurysms and arteriovenous fistulas", US2004 / 0098096 "Endograft device for inhibiting intravasation and migration", US2004 / 0176836 "Kind-resistant endovascular graft", US2005 / 0228484 "Modular endovascular graft", US2006 / 0025853 "Methods and systems for endovascular aneurysm treatment", US2008 / 0058920 "Dual-lumen cuff structure", US2008 / 0234809 "Stent graft system with injection tube", US2012 / 0316656 "Balloon expandable stent", US2012 / 0165917 "Stent graft", U S2014 / 358216 “Stent graft”, US5,330,528 “Vascular surgical device”, US5,665,117 “Endovascular prosthesis with improved sealing device for aneurysmal arterial disease and method of use thereof”, US5,693,088 “Intraluminal vascular graft”, US7,445,642 “Drug eluting stent and catheter”, US7,803,178 “Inflatable porous implant and drug delivery method” and WO95 / 28899 “Stented bioprosthetic heart valve” describe a stent (or other carrier) comprising a double-walled balloon that is expanded by introducing a fluid (e.g., blood) between the balloon walls to expand radially from the radially outer surface of the stent.

[0007] EP 2 926 766 “Repositionable Heart Valve” describes a stent having an inflatable balloon on its radially outer surface.

[0008] US 2014 / 0296975 “Inflatable annular sealing device for an artificial mitral valve” describes a stent having a skirt and a shell extending from a radially outer surface of the stent.

[0009] US2002 / 0169497 “Endovascular stent system and method for providing aneurysm embolization”, US2004 / 0082989 “Stent graft with improved proximal end”, WO2016 / 073189 “Transcatheter valve prosthesis with outer skirt for sealing and preventing paravalvular leakage” and EP2749254 “Repositionable heart valve” describe a stent having a sleeve that circumferentially covers a portion of the stent.

[0010] US Pat. No. 7,044,962 “Implantable prosthesis with a displaceable skirt” describes a stent having a skirt on its radial outer surface, said skirt having a free peripheral edge which can be deployed into an expanded state.

[0011] US2015 / 0142103 “Multi-component design of a heart valve retrieval device, sealing structure, and stent assembly,” US2016 / 0338823 “Ureteral stent and method,” US2017 / 0071734 “Transcatheter stent valve and method, system, and device for addressing paravalvular leakage,” WO2017 / 081679 “Stent graft system with skirt,” and WO2017 / 101232 “Artificial heart valve stent, artificial heart valve, and method for implanting the same” describe: (1) a stent having an outer wall and arms extending radially from the outer wall; and (2) a sleeve extending over a portion of the outer wall and radiating along the stent arms to form a skirt. In each case, the skirt extends from the outer wall and along the stent arms, from the hinged connection point between the stent arms and the outer wall, to the free end of the stent arms. Neither the sleeve nor the skirt bridges the gap between the free end of the stent arm and the outer wall.

[0012] An object of the present invention is to provide a stent with a sleeve, wherein radial expansion of the stent causes the sleeve to expand radially and form a cylindrical sleeve (in axial cross-section) having at least two protuberances supported by radially extending stent arms. Summary of the Invention

[0013] According to a first aspect of the present invention, there is provided an expandable stent with a sleeve, comprising:

[0014] a tubular body, specifically: first and second axial ends; a lattice outer wall; and at least two arms that radially project from the lattice outer wall when the tubular body radially expands from a curled state to a radially expanded state, the free end of each arm being radially movable relative to an adjacent lattice outer wall;

[0015] Sleeve, the sleeve:

[0016] extending from the first axial end of the tubular body and circumferentially covering at least a portion of the radially outer surface of the lattice outer wall between the free ends of the arms and the first axial end of the tubular body;

[0017] bridging the space between the portion of the lattice outer wall adjacent to the arm and the free end of the arm; and

[0018] secured to: (1) the arm; or (2) the tubular body in a vicinity between the free end of the arm and the second axial end of the tubular body,

[0019] Thus, as the tubular body radially expands toward the expanded state, thereby causing the arms to radially extend from the lattice outer wall, the portion of the sleeve bridging the lattice outer wall and the arms flares radially outwardly.

[0020] Typically, when the tubular body is in the curled state, the sleeve: (1) has a right cylindrical shape in a region radially overlapping the lattice outer wall; and (2) defines a radially outwardly extending ridge in a region radially overlapping the arms.

[0021] Typically, when the tubular body is in the crimped condition, the ridges defined by the sleeve provide pockets between the sleeve and respective arms into which the arms can extend as the tubular body radially expands toward the expanded condition.

[0022] Preferably:

[0023] Each arm includes: (1) a first lattice member; (2) a second lattice member that is generally U-shaped; and (3) a third lattice member that bridges the first and second lattice members; and

[0024] The sleeve extends over and is secured to the first lattice member of each arm.

[0025] Typically, for each arm, the second lattice member is unsecured to the sleeve, thereby permitting the second lattice member to slide along the sleeve within a corresponding raised region defined by the sleeve as the tubular body radially expands toward the expanded state.

[0026] Typically, the sleeve is made of an electrospun polymer.

[0027] Preferably, each ridge defined by the sleeve is kidney-shaped, curving between the axial ends of the second lattice member.

[0028] Typically, the tubular body is coated with a polymer and the sleeve is bonded to the tubular body.

[0029] Optionally, the tubular body is joined to a sector member which forms part of the lattice outer wall adjacent the second arm lattice member.

[0030] Typically: the tubular body includes three arms; and the sleeve defines three protuberances.

[0031] Preferably: the first portion of the sleeve is made of a single layer of polymer material; and the second portion of the sleeve is made of a double layer of polymer material.

[0032] According to a second aspect of the present invention, there is provided an expandable stent with a sleeve, comprising:

[0033] a tubular body having first and second axial ends; a lattice outer wall; and at least two arms projecting radially from the lattice outer wall when the tubular body radially expands from a crimped state to an expanded state, the arms, the free end of each arm being radially movable relative to an adjacent lattice outer wall; and

[0034] Sleeve, the sleeve:

[0035] extending from the first axial end of the tubular body and circumferentially covering at least a portion of the radially outer surface of the lattice outer wall between the free ends of the arms and the first axial end of the tubular body;

[0036] bridging the space between the portion of the lattice outer wall adjacent to the arm and the free end of the arm;

[0037] Covering arms; and

[0038] When the tubular body is in the curled state,

[0039] In the region where the sleeve radially overlaps the lattice outer wall, it is in the shape of a right circular cylinder; and

[0040] In the area where the sleeve radially covers the arm, a radially outwardly extending ridge is defined, providing a recess between the sleeve and the respective arm so that when the arm projects radially from the lattice outer wall, the arm extends into the recess provided by the ridge.

[0041] Typically, for each arm, the free end of the arm is unsecured to the sleeve, thereby permitting the free end of the arm to slide along the sleeve within a corresponding raised region defined by the sleeve as the tubular body radially expands toward the expanded state.

[0042] Typically: the tubular body includes three arms; and the sleeve defines three protuberances.

[0043] According to a third aspect of the present invention, there is provided a method for manufacturing an expandable stent with a sleeve, comprising the following steps:

[0044] An expandable stent is provided, comprising a tubular body having first and second axial ends; a lattice outer wall; and at least two arms, wherein the arms radially project from the lattice outer wall when the tubular body radially expands from a crimped state to an expanded state, the free end of each arm being radially movable relative to an adjacent lattice outer wall.

[0045] electrospinning a polymer onto a first cylindrical mandrel to form a sleeve;

[0046] stretching the sleeve over a second cylindrical mandrel, the second cylindrical mandrel defining at least two radially outwardly extending ridges symmetrically spaced about the second cylindrical mandrel;

[0047] heating the sleeve so that the sleeve assumes the shape of the second cylindrical mandrel having a ridge; and

[0048] The sleeve is placed over the stent so that the ridges formed in the sleeve radially cover the stent arms. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:

[0050] Figure 1 is a perspective view of an expandable stent with a sleeve according to a preferred embodiment of the first and second aspects of the present invention, wherein the expandable stent with a sleeve is in an expanded state;

[0051] Figure 2 yes Figure 1 A side view of the expandable sleeved stent shown in an expanded state;

[0052] Figure 3 yes Figure 1 An exploded perspective view of the expandable sleeved stent shown in a crimped state;

[0053] Figure 4 yes Figure 1 An exploded perspective view of the expandable sleeve stent shown in a nascent state;

[0054] Figure 5 yes Figure 1 a side view of the expandable sleeved stent shown in an expanded state, wherein the expandable sleeved stent is positioned within the aortic root; and

[0055] Figure 6 is used to form Figure 1 A perspective view of a second cylindrical mandrel forming the sleeve portion of an expandable sleeved stent is shown.

[0056] Brief description of the invention

[0057] refer to Figures 1 to 5 The expandable sleeved stent 10 includes a stent 12 and a sleeve 14 .

[0058] The stent 12 is a tubular body laser cut from a single straight cylindrical tube (typically between 18 mm and 30 mm outer diameter) to integrally form the lattice outer wall 16 and arms 18. Preferably, the stent 12 is coated with a polymer. Figure 4 The stent 12 is shown in its nascent state (ie, after laser cutting, but before being crimped).

[0059] The lattice outer wall 16 allows the stent 12 to be crimped (ie, radially compressed) under the action of the surrounding external radial compressive force. Figure 3 The curled state shown; and radially expanded to the Figure 1 The expanded state is shown.

[0060] The three arms 18 are symmetrically arranged around the bracket 12. Each arm 18 includes a first lattice member 20, a second lattice member 22 having a generally U-shape, and a third lattice member 24 bridging the first and second lattice members 20 and 22.

[0061] The lattice outer wall 16 includes a sector member 23 adjacent to each second lattice member 22 (ie, adjacent to the second lattice member 22 in a direction toward the first axial end 15 of the tubular body of the stent 12 ).

[0062] The stent 12 is described in more detail in co-pending patent application PCT / ZA2017 / 050025 (published as WO / 2017 / 190161), which is incorporated herein by reference.

[0063] Each arm 18 is hingedly movable relative to the lattice outer wall 16 between:

[0064] an initial configuration (ie, when the tubular body of the stent 12 is in a crimped state), wherein the arms 18 are aligned with the adjacent lattice outer walls 16; and

[0065] A radially protruding configuration, wherein the arms 18 protrude radially from the adjacent lattice outer wall 16 , with the free ends of the arms 18 (ie, the second arm lattice members 22 ) being displaced radially outward relative to the adjacent lattice outer wall 16 .

[0066] Expansion of the stent 12 from the crimped state to the expanded state causes the arms 18 to move from the initial configuration to the radially projecting configuration.

[0067] The sleeve 14 is generally right cylindrical in shape and defines three radially outwardly extending ridges 26 .

[0068] The sleeve 14 is formed in the following manner:

[0069] Electrospinning the polymer onto a first cylindrical mandrel (not shown);

[0070] On the second cylindrical core shaft 28 (such as Figure 6 ) upper stretch sleeve 14, the second cylindrical mandrel 28 defines three radially outwardly extending kidney-shaped protrusions 30 symmetrically spaced about the second cylindrical mandrel 28;

[0071] • Heating the sleeve 14 so that the sleeve 14 takes on the shape of the second cylindrical mandrel 28 (with the kidney-shaped ridge).

[0072] The sleeve 14 is placed on the bracket 12 (when the tubular body of the bracket 12 is in Figure 4 In the newly formed state shown, the protuberances 26 formed on the sleeve 14 radially cover the arms 18 of the stent 12. More specifically, the sleeve 14:

[0073] In the area radially overlapping with the covering lattice outer wall 16, its shape is a right cylindrical shape; and

[0074] In the region radially overlying the arms 18 , there are defined: (a) radially outwardly extending kidney-shaped protuberances 26 curved between the axial ends of the second lattice members 22 ; and (b) pockets 32 between the protuberances 26 and the corresponding arms 18 .

[0075] The sleeve 14 is coupled to the first axial end 15 of the tubular body of the bracket 12 and extends from the first axial end 15 of the tubular body of the bracket 12 to circumferentially cover at least a portion of the radially outer surface of the lattice outer wall 16 between the free ends of the arms 18 (i.e., the second lattice member 22) and the first axial end 15 of the tubular body of the bracket 12. The sleeve 14 further extends along the tubular body of the bracket 12 to bridge the space between the portion of the lattice outer wall 16 adjacent to the arms 18 and the free ends of the arms 18 (i.e., the second lattice member 22). The sleeve 14 can be fixed (i.e., coupled) to the free ends of the arms 18 (i.e., the second lattice member 22). Alternatively, (if shown), the sleeve 14 can be fixed (i.e., coupled) to the first lattice member 20. Additionally, the sleeve 14 may extend beyond the arm 18 and be secured (i.e., bonded) to the tubular body of the bracket 12 approximately between the free end of the arm 18 (i.e., the second lattice member 22) and the second axial end 17 of the tubular body of the bracket 12. Preferably, the sleeve 14 is also bonded to the sector member 23.

[0076] Since the stent 12 is coated with a polymer, the sleeve 14 may bond to the polymer coating on the stent 12 .

[0077] The bracket 12 with the sleeve 14 thereon is then crimped to Figure 3 The curled state shown.

[0078] When the expandable sleeved stent 10 is radially expanded:

[0079] The tubular body of the stent 12 expands radially.

[0080] The free end of the arm 18 is displaced / protrudes radially outward from the adjacent lattice outer wall 16. Preferably, the free end of the arm 18 (i.e., the second arm lattice member 22) is not fixed to (i.e., not bonded to) the sleeve 14, so that radial extension of the arm 18 from the adjacent lattice outer wall 16 causes: (1) the free end of the arm 18 (i.e., the second arm lattice member 22) to extend into the recess 32 defined by the ridge 26 of the sleeve 14 and slide along the radially inner surface of the ridge 26 defined by the sleeve 14; and (2) the portion of the sleeve 14 bridging the lattice outer wall 16 and the arm 18 to flare radially outward.

[0081] When the stent 12 is in the expanded state, the arms 18 provide support to the protuberance 26 defined by the sleeve 14 to resist radially inward collapse of the protuberance 26 .

[0082] Although the sleeve 14 may be made from a single layer of polymer material, portions of the sleeve 14 may be reinforced with a second polymer to withstand the large pressure differential surface area across the sleeve 14 during use.

[0083] Optionally, the expandable sleeved stent 10 includes a valve in the axial direction of the stent 12 .

[0084] By extending sleeve 14 from first axial end 15 of stent 12 beyond the free ends of arms 18, expandable sleeved stent 10 increases the sleeved axial length of stent 12 with radially expanded arms 18. Furthermore, by extending arms 18 radially inwardly of sleeve 14 (i.e., within ridges 26 defined by sleeve 14), expandable sleeved stent 10 increases the axial cross-sectional area sealed by sleeve 14. Furthermore, due to the radial expansion of sleeve 14 near ridges 26 by arms 18, the portion of sleeve 14 protruding into the sinus (i.e., ridges 26) is mechanically supported by radially projecting arms 18 in this radially extended state. Furthermore, because sleeve 14 bridges the gap between the free ends of arms 18 and the adjacent lattice outer wall 16, sleeve 14 provides an effective continuous non-circular seal (i.e., with the additional ridges / protrusions formed thereby) when viewed in axial cross-section near ridges 26.

[0085] combination:

[0086] Increase the axial length of the sleeve 14 along the bracket 12;

[0087] Mechanically supporting the ridge 26 defined by the sleeve 14 in a radially projecting state;

[0088] the gap between the free end of the bridging arm 18 and the adjacent lattice outer wall 16; and

[0089] Provides a continuous non-circular seal in the axial cross section (near the ridge 26),

[0090] The expandable sleeved stent 10 is suitable for addressing leaks (including paravalvular leaks) that result from positioning and expanding the expandable sleeved stent 10: too low within the cardiovascular system; or adjacent to a large sinus or aneurysm.

Claims

1. An expandable stent with a sleeve, comprising: a tubular body having: first and second axial ends; a lattice outer wall; and at least two arms, wherein when the tubular body radially expands from a curled state to an expanded state, the arms radially protrude from the lattice outer wall, and a free end of each arm is radially displaceable relative to an adjacent lattice outer wall; Sleeve: extending from the first axial end of the tubular body and circumferentially covering at least a portion of the radially outer surface of the lattice outer wall between the free ends of the arms and the first axial end of the tubular body; bridging the space between the portion of the lattice outer wall adjacent to the arm and the free end of the arm; as well as is secured to: (1) the arm; or (2) the tubular body in the vicinity between the free end of the arm and the second axial end of the tubular body, When the tubular body is in the curled state, the sleeve: (1) has a right cylindrical shape in a region radially overlapping the lattice outer wall; and (2) defines a radially outwardly extending protuberance in a region radially overlying the arm, the protuberance providing a recess between the sleeve and the corresponding arm, into which the arm extends when the tubular body radially expands toward the expanded state; Thus, as the tubular body radially expands toward the expanded state, thereby causing the arms to radially extend from the lattice outer wall, the portion of the sleeve bridging the lattice outer wall and the arms will flare radially outwardly.

2. The expandable stent with sleeve according to claim 1, wherein: Each arm includes: (1) a first lattice member; (2) a second lattice member that is generally U-shaped; and (3) a third lattice member that bridges the first and second lattice members; and the sleeve extends and is fixed to the first lattice member of each arm.

3. The expandable stent with sleeve according to claim 2, characterized in that: For each arm, the second lattice member is unsecured to the sleeve, thereby allowing the second lattice member to slide along the sleeve within a corresponding raised region defined by the sleeve as the tubular body radially expands toward the expanded state.

4. The expandable stent with sleeve according to claim 3, wherein: The sleeve is made of electrospun polymer.

5. The expandable stent with sleeve according to claim 4, characterized in that: Each ridge defined by the sleeve is kidney-shaped and curved between the axial ends of the second lattice member.

6. The expandable stent with sleeve according to claim 5, characterized in that: The tubular body is coated with a polymer, and the sleeve is bonded to the tubular body.

7. The expandable stent with sleeve according to claim 6, characterized in that: The sleeve is coupled to a sector member that forms a portion of a lattice outer wall adjacent to the second arm lattice member in a direction toward the first axial end of the tubular body of the stent.

8. The expandable stent with sleeve according to claim 7, characterized in that: The tubular body includes three arms; and the sleeve defines three ridges.

9. An expandable stent with a sleeve, comprising: a tubular body having: first and second axial ends; a lattice outer wall; and at least two arms, wherein when the tubular body radially expands from the curled state to the expanded state, the arms radially protrude from the lattice outer wall, and the free end of each arm is radially movable relative to the adjacent lattice outer wall; and A sleeve, wherein: extending from the first axial end of the tubular body and circumferentially covering at least a portion of the radially outer surface of the lattice outer wall between the free ends of the arms and the first axial end of the tubular body; bridging the space between the portion of the lattice outer wall adjacent to the arm and the free end of the arm; Covering arms; and When the tubular body is in a curled state: In the region where the sleeve radially overlaps the lattice outer wall, it is in the shape of a right circular cylinder; and In areas where the sleeve radially covers the arms, radially outwardly extending protuberances are defined, providing recesses between the sleeve and the respective arms, such that when the arms extend radially from the lattice outer wall, the arms extend into the recesses provided by the protuberances.

10. The expandable stent with sleeve according to claim 9, characterized in that: For each arm, the free end of the arm is unsecured to the sleeve, thereby allowing the free end of the arm to slide along the sleeve within a corresponding raised region defined by the sleeve as the tubular body radially expands toward the expanded state.

11. The expandable stent with sleeve according to claim 10, characterized in that: The tubular body includes three arms; and the sleeve defines three protuberances.

12. A method for manufacturing an expandable stent with a sleeve, comprising the following steps: An expandable stent is provided comprising a tubular body having: first and second axial ends; a lattice outer wall; and at least two arms, wherein when the tubular body radially expands from a curled state to an expanded state, the arms radially project from the lattice outer wall, and a free end of each arm is radially movable relative to an adjacent lattice outer wall; electrospinning a polymer onto a first cylindrical mandrel to form a sleeve; and stretching the sleeve onto a second cylindrical mandrel, the second cylindrical mandrel defining at least two radially outwardly extending ridges symmetrically spaced about the second cylindrical mandrel; The sleeve is heated so that the sleeve assumes the shape of a second cylindrical mandrel having a ridge; and the sleeve is placed on the bracket so that the ridge formed on the sleeve radially covers the bracket arm.

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