Shape-memory polymer foam seals the space around the valve

Abstract

To provide shape memory polymer (SMP) foams to seal space around heart valves.SOLUTION: An embodiment includes individual SMP foams that radially expand and fill gaps around a heart valve that may be improperly fixed, in an unusual cross section, or has poor apposition against a calcified lesion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] PRIORITY: This application claims priority to U.S. Provisional Patent Application No. 62 / 471,131, entitled "Shape Memory Polymer Foams to Seal Space Around Valves," filed March 14, 2017, the contents of which are incorporated herein by reference. TECHNICAL FIELD: The present invention relates to the field of medical devices, particularly valves. [Background technology]

[0002] Surgery to replace a heart valve (e.g., aortic or mitral valve) is performed for a variety of reasons, including mitral, aortic, pulmonary, or tricuspid valve stenosis or regurgitation. In this procedure, the damaged valve is removed and replaced with a prosthetic valve. Valve replacement is usually an open-heart procedure; however, patients also have the option of minimally invasive surgery or the placement of a catheter in place of the valve. Prosthetic valves can be mechanical (made from artificial materials) or made from animal tissue. Summary of the Invention

[0003] Paravalvular or paraprosthetic leak (PVL) is a complication associated with the implantation of a prosthetic heart valve, either by conventional (surgical) or transcatheter (TAVI) approach. Paravalvular or paraprosthetic leak refers to the leakage of blood through a channel between the implanted valve structure and the heart tissue as a result of an improper seal. Most PVLs are crescent, oval, or circular, and their path can be parallel, perpendicular, or serpentine. The incidence of PVL, including small, non-significant ejections, is estimated to be as high as 20%. PVL is also more common in the mitral valve (up to 20%) than in the aortic valve.

[0004] Features and advantages of embodiments of the present invention will become apparent from the appended claims, the following detailed description of one or more exemplary embodiments, and the corresponding drawings. Where considered appropriate, reference labels in the figures have been repeated to indicate corresponding or analogous elements. [Brief explanation of the drawings]

[0005] [Figure 1] In one embodiment, the stent comprises a shape memory polymer (SMP) foam substantially covering the fenestrations.

[0006] [Figure 2] A shows a radially compressed SMP foam in one embodiment. B shows a radially expanded SMP foam.

[0007] [Figure 3] A shows a radially compressed SMP foam in one embodiment, and B shows the radially compressed foam and stent after compression of the stent for delivery to a patient.

[0008] [Figure 4] In one embodiment, a radiopaque monolithic SMP foam ring is included, which also demonstrates the machinability (i.e., ability to form the foam into various shapes and sizes) for that embodiment.

[0009] [Figure 5] A shows a low density foam matrix in one embodiment, and B shows a high density foam doped with radio-opacity.

[0010] [Figure 6] A shows expanded SMP foam. B shows SMP foam when pressed / compressed. C shows SMP foam when pressed / compressed.

[0011] [Figure 7]1 shows various shapes and sizes that demonstrate the machinability of embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] Reference is now made to the drawings, in which like structures may be provided with like reference symbols at the end. The drawings included herein are schematic and more clearly illustrate the structure of various embodiments. Thus, the actual appearance of a manufactured structure, for example in a photograph, may appear different while still incorporating the claimed structure of the illustrated embodiment. Furthermore, the drawings may only show structures useful for understanding the illustrated embodiment. Additional structures known in the art may not be included to maintain clarity of the drawings. Terms such as "embodiments," "various embodiments," and the like refer to the described embodiments, although not all embodiments necessarily include a particular feature, structure, or characteristic.

[0013] Some embodiments may have some or all features described with respect to other embodiments. Terms such as "first," "second," and "third" describe a common object and also indicate different instantiations of the similar object being referenced. Such adjectives do not imply that the described objects are described in a given sequence, or temporally, spatially, ordered, or otherwise. The term "connected" may indicate that elements are in direct physical or electrical contact with each other, and "coupled" may indicate that elements cooperate or interact with each other, but may or may not be in direct physical or electrical contact.

[0014] Many of the embodiments addressed herein relate to perivalvular leaks, but the embodiments relate more generally to leaks involving implanted valves, whether they be cardiac valves, peripheral venous valves, or other valves.

[0015] Applicant has attempted to use conventional materials, such as PET (Dacron) "skirts," to fill the paravalvular space and promote tissue integration. However, Applicant has further discovered that this technique does not adequately volumetrically fill the perivalvular space or promote tissue integration. In the embodiments described herein, a shape memory polymer (SMP) foam is used to fill the perivalvular space and promote tissue integration.

[0016] For example, one embodiment involves the use of SMP foams incorporated around the annulus of a heart valve to reduce perivalvular flow and promote device integration into the surrounding tissue. More specifically, the SMP foams expand to fill the voids around the valve, which may be improperly secured, have an abnormal cross-section, or poorly apposed to calcified lesions. For example, radial expansion of the foams provides volumetric filling around the device. This applies to surgically implanted valves, and the shape-memory capabilities of the foams are particularly useful for intravascular valve delivery.

[0017] While many of the embodiments herein involve radial compression of the SMP foam (and subsequent radial expansion of the SMP foam), other embodiments may use axial compression / expansion and / or circumferential compression / expansion.

[0018] Once implanted, the foam seals perivalvular leakage and promotes tissue integration to achieve sustained occlusion. The porous morphology of the foam promotes acute thrombosis and sealing of the device. Over time, the thrombus is replaced by integrated tissue, resulting in a sustainable seal and integration of the device into the surrounding tissue.

[0019] One embodiment includes a monolithic foam annulus bonded to the valve. See, for example, the foam annulus in Figure 4. Bonding can include weaving valve support struts through the foam (see, for example, Figure 1), bonding the valve support struts to the foam, and / or coating the valve support struts with a polymer (e.g., polyurethane) film and bonding the foam to the polymer film. Attaching the foam to the valve support structure ensures that the foam does not fall off or migrate downstream and block the blood vessel.

[0020] As shown in Figure 2B, one embodiment includes a closed cell "scale" glued to the device.

[0021] In one embodiment, nitinol wires are threaded through a polymer foam (see Figures 1 and 3A). The wire structures are threaded through the foam and then bonded together to form a support structure.

[0022] In one embodiment, the bottom of the SMP "scale" is not bonded to the nitinol frame (see FIGS. 1, 3A, and 3B). Foam "scale" embodiments adjust the anisotropic strain (see, e.g., FIG. 3B) to accommodate the valve support structure within the delivery catheter during radial compression. For example, the support structure's windows contract along the circumferential axis (see, e.g., the "horizontal" arrow in FIG. 3A, which shows the movement of the nitinol windows), but expand axially (see, e.g., the "vertical" arrow in FIG. 3A, which shows the movement of the nitinol windows). In other words, the bottom of the scale is free and does not experience significant tension that could cause the foam to burst.

[0023] In one embodiment, the SMP "scale" includes windows (see the top voids in the SMP foam in Figure 1) for welding adjacent support struts together.

[0024] Other scales include Figures 5A, 5B, 6A, 6B, 6C, and 7. The foam shape factors shown in Figures 5A-7 represent different degrees of area filling within each "window" of the support structure. Varying the foam shape factor can change the degree of radial compression and folding of the scale after compression. When a flat foam scale is radially compressed, it folds similarly to a catheter balloon, minimizing the crimped cross-sectional area for proper placement during delivery.

[0025] While many of the above embodiments relate to sealing valves, particularly heart valves, other embodiments may be, but are not limited to, sealing abdominal aortic aneurysms (AAA) stent grafts, and the like.

[0026] One embodiment includes foams obtained by reacting one or more polyols (e.g., HPED and / or TEA) with one or more diisocyanates (e.g., hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), and / or isophorone diisocyanate) to form polyurethane SMPs. Embodiments include HDI, TMHDI, isophorone diisocyanate, triethanolamine, diethanolamine, butanediol, butynediol, N, Examples include polyurethane SMP foams synthesized by several combinations of N,N',N' tetrakis(hydroxypropylene)ethylenediamine.

[0027] Other embodiments include X-ray visible SMP foams. For example, one embodiment includes foams obtained by reacting one or more polyols (e.g., 5-amino-2,4,6-triiodoisophthalic acid; 3-methyl-1,5-pentanediol; 2-butyl-2-ethyl-1,3-propanediol; hexanetriol; butanetriol) with one or more diisocyanates (e.g., HDI) to form polyurethane SMPs.

[0028] Embodiments provide various means to ensure protection of the foam during transport of the device.

[0029] In one embodiment, the valve is delivered through a large diameter catheter / sheath, which allows for a large delivery "ramrod" (which can accommodate significant friction from the inflation device) from which the valve is deployed. Because the foam is bonded to the support structure (e.g., it may be bonded to the struts or locally bonded across the entire area of ​​the fenestration), it does not shear during delivery.

[0030] In some transcatheter embodiments, the expansion of the foam is delayed. For example, the device can be stored well below body temperature and programmed for rapid expansion time once body temperature is reached (which may be above the wet Tg of the foam). The foam can be stored in its moisture-plasticized state.

[0031] Surgical implantation (as opposed to transcatheter implantation) may operate at or above body temperature for the foam.

[0032] In some embodiments (eg, transcatheter or surgical implantation), the foam is expanded with warm saline at the end of preparation.

[0033] If foam is used instead of a traditional Dacron skirt, one embodiment would be to place the foam in a lubricious sheath (e.g., made from PTFE) that the surgeon removes when ready to deploy the device, which would minimize shear forces on the foam given that, for example, PTFE is more slippery / less resistant than many PU catheters.

[0034] Embodiments include low and / or high density foams. In embodiments, density is used to balance the mechanical strength of the foam (e.g., higher density reduces foam crimping ability) with minimizing the crimp diameter. One embodiment includes foams with pore sizes between 50 and 1500 microns.

[0035] In some embodiments, the foam never expands into the main vessel. For example, the foam is sufficiently adhered to the support structure to expand radially abluminally. The foam's attachment to the valve must not damage the ventricle. For example, in one embodiment, a mechanical restraint is used to prevent the foam from expanding radially inward into the main vessel. For example, a valve may prevent the foam from expanding inward. As another example, a polymer membrane disposed between the foam and the inner channel of the device may prevent the foam from expanding inward.

[0036] Embodiments may include scales that are not all identical. For example, one embodiment may include multiple rows of scales, some of which may be half-scale and others of which may be full-scale. The rows may be interchanged within the scale and / or between the scale magnitudes of two different patterns.

[0037] In one embodiment, a Dacron skirt and SMP foam are used together, for example, the Dacron skirt acts like a "sheath" that folds over the crimped foam to facilitate delivery.

[0038] Embodiments may be used in different pressure environments (e.g., venous versus arterial pressure), and may use different pore sizes / formation factors.

[0039] Embodiments may also address perivalvular leakage in venous valve replacement devices, such as the vena cava.

[0040] FIG. 1 illustrates a system 100 having a stent including first, second, third, and fourth struts 101, 102, 103, 104. The stent further includes first, second, third, fourth, and fifth fenestrations 111, 112, 113, 114, 115. A valve 121 is contained within the stent (best seen in FIG. 2B). An outer conduit contains an open-cell polyurethane thermoset SMP foam 131 configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus. In FIG. 1, the first and third fenestrations 111, 113 share the first strut 101 and are both directly adjacent to the first strut. The second and third fenestrations 112, 113 share the second strut 102 and are both directly adjacent to the second strut. The fourth and third fenestrations 113, 113 share the third strut 103 and are both directly adjacent to the third strut. The fifth and third windows 115, 113 share, and are both immediately adjacent to, the fourth strut 104. Although struts 101, 103 may be contained in a single monolithic length of wire, and they constitute other "struts," the term "strut" is used herein.

[0041] In Figure 1, SMP foam 131 substantially covers at least 80% of the first face of the third window. This "face" is perhaps 95% (or more) obscured in the embodiment of Figure 1, and the face is primarily formed by the struts 101, 102, 103, 104.

[0042] In one embodiment, the first, second, third, and fourth struts each include a shape memory metal such as Nitinol. However, other embodiments are not limited thereto and may include stainless steel or other metals. The non-shape memory metal may be deployed by a balloon or other inflatable device. Other embodiments include surgically implanted valves.

[0043] In Figure 1, the first and second struts 101, 102 rigidly connect the SMP foam, while the third and fourth struts 103, 104 do not rigidly connect the SMP foam. The applicability of this arrangement extends as follows: foam 131 may contact strut 103, but is not "fixed" to strut 103; when strut 103 deflects due to stent elongation, foam 131 does not necessarily move with the strut. However, foam 131 is fixed to strut 101 and moves as strut 101 moves. In other words, the movement of foam 131 is dependent on strut 101, not strut 103.

[0044] In a first orientation (e.g., when the system is in packaging for shipment to a medical facility), the outer diameter of the stent is a first maximum stent outer diameter. As shown in Figure 3B, the length of the fenestrations 313 (similar to the fenestrations 113 in Figure 1) is a first fenestrations length 341 measured parallel to the stent's major axis 341. The fenestrations are also perpendicular to the stent's major axis, and the fenestrations have a first fenestrations width 342' measured parallel to the stent's minor axis 343. The SMP foam 331 is in a compressed, secondary state.

[0045] In the second direction, the outer diameter of the stent is a second maximum outer stent diameter 342 that is longer than the first maximum outer stent diameter 342'. This occurs because the stent is compressed (possibly collapsing) and the trajectory of the stent is reduced (as the stent is prepared for implantation). In this case, the stent is elongated along axis 341 and necked (narrowed) along axis 343. As a result, the fenestration length of fenestration 313 is a second fenestration length 340 that is shorter than first fenestration length 340'. Also, the width of fenestration 313 is a second fenestration width 342 that is wider than first fenestration width 342'. The SMP foam is in its expanded primary state in the second direction.

[0046] In contrast to the change in length of window 313, the body length of SMP foam 331 remains the same (at least in some embodiments) in the compressed and expanded states. For example, length 344' is substantially the same (+ / - 3%) as length 344. In some embodiments, the width of the foam may be the same in the compressed and expanded states (though the width appears to change in FIGS. 3A and 3B, in some embodiments, the foam width remains the same). Consistency in the length and width of the foam is considered before folding or creasing of the system occurs. In some embodiments, foam 331 is compressed only radially (into the page in FIG. 3A), with little or no compression / expansion in the axial (along axis 341) or circumferential (generally along axis 343) directions.

[0047] Applicant has noted that the existence of these "crimping dynamics" and the potential for greater deformation (i.e., axially) of a metal stent than an SMP foam are significant issues. Applicant has further noted that metals, such as Nitinol, have a relatively low strain capacity (e.g., 4%), while SMP foams have a relatively high strain capacity. That is, if a metal stent deforms significantly axially (along axis 341), the deformation may be greater than the axial deformation of the SMP foam. For example, an SMP foam may have little or no axial deformation. Thus, a radially compressed SMP foam may not deform to the extent of metal window length difference 340" (340' - 340 = 340"). In various embodiments, the axial extension of the foam may be 0, 5, 10, 15, or 20% of axial difference 340".

[0048] In response to these crimping dynamics, one embodiment secures foam 331 to some struts of the stent but not to others. For example, in FIG. 1 , SMP foam 131 securely connects struts 101, 102 at locations 151, 151′ and 152, 152′. At locations 151, 151′ and 152, 152′, struts 101, 102 repeatedly penetrate SMP foam 131 to secure foam 131 to the stent. In other words, strut 101 penetrates SMP foam 131 at at least one location (e.g., location 151) such that a first strut traverses from a first surface of the SMP foam (the front surface in FIG. 1 ) to a second surface of the SMP foam (the rear surface not visible in FIG. 1 ) such that the first and second surfaces face each other. Note that the bottom half of SMT foam 131 is not fixedly attached to posts 103, 104. In response to first and second posts 101, 102 being fixedly connected to SMT foam 131 and third and fourth posts 103, 104 not being fixedly connected to the SMT foam, the SMT foam is configured to move in response to the first and second posts and move independently of the third and fourth posts when the device transitions from the first orientation to the second orientation. For example, in Figures 3A and 3B, foam 331 will move up and down (or up and down along axis 341) when posts 301, 302 move up and down along axis 341. However, excessive downward deflection by posts 303, 304 will not break or damage the cells of SMT foam 331 because the foam is largely independent of the movement of posts 303, 304.

[0049] Regarding the connection of foam 131 to the various struts, the SMP foam can also be connected to the stent in other ways. For example, in one embodiment, an adhesive (e.g., UV epoxy welds using Dymax 203A-CTH-F to connect the nitinol struts to the polyurethane of the SMP foam) connects SMP foam 131 to the first and second struts 101, 102. The adhesive may be applied along lengths 161, 162, but is not present along lengths 161', 162', nor on struts 103, 104. The adhesive is not visible in FIG. 1 because it is between foam 131 and the struts. Masking may be used in areas 161', 162', 103, 104 to ensure that no adhesive is applied thereto. The masking (e.g., oxide or nitride) may be removed later in the process in some embodiments.

[0050] In one embodiment, the adhesive includes an unfoamed polyurethane coating that directly contacts and is fixedly attached to the first strut 101. The SMP foam 131 directly contacts and is fixedly bonded to the polyurethane coating. As a result, the polyurethane coating fixedly bonds the SMP foam 131 to the first strut 101. Thus, when the polyurethane foam bonds to other polyurethanes, the bond between the adhesive and the foam becomes stronger. For example, the unfoamed polyurethane coating can be neat polyurethane.

[0051] In one embodiment, the polyurethane coating is a cured thermoset. However, in other embodiments, the polyurethane coating is a thermoplastic. According to one embodiment, the chemical composition of the polyurethane coating is identical to that of the SMP foam. Therefore, the adhesion between the foam and the adhesive is "like to like" and therefore reliable. For example, both the SMP foam and the adhesive coating may be obtained from the reaction between one or more polyols (e.g., HPED and / or TEA) and one or more diisocyanates (e.g., hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), and / or isophorone diisocyanate).

[0052] In one embodiment, the polyurethane coating is an SMP. The chemical composition of the SMP coating can be the same as the chemical composition of the SMP foam. In one embodiment, the SMP coating is foamed to provide a first foam (inner foam) that connects a second foam (outer foam 131) to the stent struts.

[0053] Further, regarding the construction of foam 131, in one embodiment, the SMP foam is covalently bonded with iodine to form a foam that is visible under X-ray imaging (i.e., radiopacity). Also, regarding radiopacity, in one embodiment, the SMP foam is poly(urethane-urea-amide). In one embodiment, the iodine includes triiodobenzene monomer.

[0054] As noted above, in the compressed state, foam 131 is radially compressed along radius 155, which is perpendicular to both stent major axis 141 and stent minor axis 143. This is better seen in Figures 2A (compressed) and 2B (radially expanded).

[0055] In various embodiments, one or more foam segments are used in various ways.

[0056] For example, in Figure 1, SMP foam 131 substantially covers a majority of the surface of window 113, but does not cover a majority of the surface of any of the first, second, fourth, and fifth windows 111, 112, 114, and 115. In the embodiment of Figure 1, window 113 is directly adjacent to each of the first, second, fourth, and fifth windows 111, 112, 114, and 115. There are no other stent windows between window 114 and any of windows 111, 112, 114, and 115.

[0057] For example, Figure 2A discloses SMP foam 131. Additionally, Figure 2A includes an additional open-cell polyurethane thermoset SMP foam 132, configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus. Foam 132 substantially covers a first side of fourth window 215, the fourth window having opposing first and second sides. At least a portion of fourth strut 104 securely connects additional SMP foam 132 (but not foam 131). In a first orientation, the additional SMP foam is in a compressed secondary state, and in a second orientation, the additional SMP foam is in an expanded primary state.

[0058] In one embodiment, foam 131 may be expanded slightly such that foam 131 extends to boundary 131'. As a result, the expanded SMP foam 131 and the further SMP foam 132 overlap each other (see area 133 for the overlapping area) and an axis (see dot 155' indicating the axis into the page) intersects both the SMP foam 131 and the further SMP foam 132. Axis 155' is perpendicular to the stent major axis 141 and the stent minor axis 143.

[0059] As can be seen in Figure 2A, SMP foam 131 has a first surface area. Additional foam 132 has a second surface area. The first surface area is at least 20% greater than the second surface area. However, in other embodiments, one foam segment may have a surface area that is 30, 40, 50, 60, 70, 80, 90% or more greater than the other foam segment.

[0060] In the embodiment of FIG. 2B , foam 131 coexists with foam 135. An additional open-cell polyurethane thermoset SMP foam 135 is configured to expand from a compressed, secondary state to an expanded, primary state in response to a thermal stimulus. The additional SMP foam 135 substantially covers a first side of a sixth window 216 included in the stent, the sixth window having opposing first and second sides. The other SMP foam 135 does not substantially cover the third window 113. SMP foam 131 does not substantially cover the sixth window 216. An additional strut 201 is included in the sixth window 216 and securely connects the additional SMP foam 135 (similar to how strut 101 connects foam 131). In a first orientation, the additional SMP foam 135 is in a compressed, secondary state, and in a second orientation, the additional SMP foam is in an expanded, primary state.

[0061] 1 , a first plane 157 parallel to the stent minor axis 143 intersects the SMP foam 131, the first and second struts 101, 102, and the first, second, and third fenestrations 111, 112, 113. A second plane 158 parallel to the stent minor axis intersects the SMP foam 131, the third and fourth struts 103, 104, and the third, fourth, and fifth fenestrations 113, 114, 115. The first plane 157 does not intersect with either the third or fourth struts 103, 104. The first plane 157 does not intersect with either the fourth or fifth fenestrations 114, 115. The second plane 158 does not intersect with either the first or second struts 101, 102. The second plane 158 does not intersect with either the first fenestrations 111 or fenestrations 112.

[0062] In the embodiment of Figure 1, a first strut 101 connects to a second strut 102 at a first junction 108. An axis 109 (see dot into the page) intersects the first junction but does not contact the SMP foam 131. The axis 109 is perpendicular to the major axis 141 of the stent and the minor axis 143 of the stent. As described above, strut 101 may be "attached" through foam 131, after which struts 101, 102 are connected (e.g., welded) to one another. Thus, a window or void with sidewalls 107, 107' may be formed such that the connection (e.g., welding) can occur without interference from the existing foam 131.

[0063] With respect to the "outer conduit" above, embodiments may use a conduit (e.g., a tube, sheath, skirt, catheter) to deploy the foam / stent system. In one embodiment, the outer conduit may include polytetrafluoroethylene (PTFE), extruded PTFE (ePTFE), or other relatively low friction material that limits shear forces in the SMP foam.

[0064] Some embodiments may include other conduits in addition to or instead of the "outer conduit" described above. For example, one embodiment may include an inner conduit (such as a polyurethane membrane) between the valve and the SMP foam. For example, a Dacron skirt (or any of various polymer skirts / conduits in various embodiments, such as a polyurethane skirt) may be between the valve and the stent and function to ensure that the SMP foam does not expand within the main vessel (e.g., the aorta). In other embodiments, an inner conduit may be between the stent and the SMP foam. An adhesive may connect the foam to the inner conduit. The inner conduit may be connected to the struts. In this manner, the foam is connected to the struts via the adhesive and the inner conduit. In one embodiment, an unfoamed SMP adhesive bonds the SMP foam (which has the same chemical composition as the adhesive) to a non-shape memory inner conduit (e.g., a polyurethane inner conduit) connected to the stent.

[0065] As shown in FIG. 4, one embodiment includes an SMP foam comprising a monolithic SMP foam ring. The SMP foam ring may be external to the stent and surround the stent. The ring may include folds or pleats that facilitate controlled and repeatable collapse of the ring when the stent is collapsed to minimize its implanted profile. The upper half of the ring may be secured to the struts, while the lower half of the ring may be unsecured, preventing excessive stretching of the lower half when the stent is axially stretched. While the embodiment of FIG. 4 may be small and suitable for peripheral vessels (e.g., venous valves), other embodiments may be larger to surround heart valves, etc.

[0066] The following examples relate to further embodiments.

[0067] Example 1: A device comprising: (a) a stent including (i) first, second, third, and fourth struts and (a)(ii) first, second, third, fourth, and fifth fenestrations; a valve contained within the stent; a cellular polyurethane thermoset shape memory polymer (SMP) foam, the SMP foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus; and an outer conduit, wherein: (b)(i) (b)(ii) the first and third windows share the first support pillar and are both directly adjacent to the first support pillar, (b)(iii) the fourth and third windows share the third support pillar and are both directly adjacent to the third support pillar, and (b)(iv) the fifth and third windows share the fourth support pillar and are both directly adjacent to the fourth support pillar; the third window has first and second opposing faces, and the SMP foam has (c)(i) the first and second struts securely connect the SMP foam, but (c)(ii) the third and fourth struts do not securely connect the SMP foam; in a first orientation, (d)(i) the stent has a first stent maximum outer diameter, (d)(ii) the third fenestration has a first fenestration length measured parallel to a longitudinal axis of the stent, and (d)(iii) the third fenestration has a first fenestration length measured perpendicular to a longitudinal axis of the stent, and the stent and (d)(iv) the SMP foam is in the compressed secondary state; in a second direction, (e)(i) the stent has a second maximum stent outer diameter that is longer than the first maximum stent outer diameter, (e)(ii) the third fenestrations have second fenestrations lengths that are shorter than the first fenestrations lengths, (e)(iii) the third fenestrations have second fenestrations widths that are wider than the first fenestrations widths, and (e)(iv) the SMP foam is in the expanded primary state;and wherein, in response to the first and second struts rigidly connecting the SMP foam and the third and fourth struts not rigidly connecting the SMP foam, the SMP foam is configured to move reliant on the first and second struts but independent of the third and fourth struts when the device transitions from the first orientation to the second orientation;

[0068] In other embodiments, the SMP foam substantially covers at least 50, 60, 70, 90% of the first surface of the third window.

[0069] In another aspect of Example 1, a device is provided comprising: (a) a stent including (i) first, second, third, and fourth struts and (a)(ii) first, second, third, fourth, and fifth fenestrations; a valve contained within the stent; a cellular polyurethane thermoset shape memory polymer (SMP) foam, the SMP foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus; and an outer conduit, wherein: (b)(i) the (b)(ii) the first and third windows share the first support pillar and are both directly adjacent to the first support pillar, (b)(ii) the second and third windows share the second support pillar and are both directly adjacent to the second support pillar, (b)(iii) the fourth and third windows share the third support pillar and are both directly adjacent to the third support pillar, and (b)(iv) the fifth and third windows share the fourth support pillar and are both directly adjacent to the fourth support pillar; the third windows have opposing first and second faces, and the SMP foam is positioned on substantially at least one of the first faces of the third windows. the first, second, third, and fourth struts each comprise a shape memory metal; (c)(i) the first and second struts fixedly connect the SMP foam, but (c)(ii) the third and fourth struts do not fixedly connect the SMP foam; in a first direction, (d)(i) the stent has a first maximum stent outer diameter, (d)(ii) the third fenestration has a first fenestration length measured parallel to a longitudinal axis of the stent, and (d)(iii) the third fenestration has a first fenestration length measured perpendicular to the longitudinal axis of the stent; (d)(iv) the SMP foam is in the compressed secondary state; in a second direction, (e)(i) the stent outer diameter has a second maximum stent outer diameter that is greater than the first maximum stent outer diameter, (e)(ii) the third fenestrations have second fenestrations lengths that are less than the first fenestrations lengths, (e)(iii) the third fenestrations have second fenestrations widths that are greater than the first fenestrations widths, and (e)(iv) the SMP foam is in the expanded primary state;and wherein, in response to the first and second struts rigidly connecting the SMP foam and the third and fourth struts not rigidly connecting the SMP foam, the SMP foam is configured to move reliant on the first and second struts but independent of the third and fourth struts when the device transitions from the first orientation to the second orientation;

[0070] In another aspect of Example 1, a device includes: (a) a stent including first, second, third, and fourth struts, and (a)(ii) first, second, third, fourth, and fifth fenestrations; a valve contained within the stent; an open-cell polyurethane thermoset shape memory polymer (SMP) foam, the SMP foam having been expanded from a compressed secondary state to an expanded primary state; and an outer conduit containing the stent; wherein: (b)(i) the first and third fenestrations share the first strut and are both immediately adjacent to the first strut; (b)(ii) the second and third fenestrations share the second strut and are both immediately adjacent to the second strut; (b)(iii) the fourth and third fenestrations share the third strut and are both immediately adjacent to the third strut; and (b)(iv) the fifth and third fenestrations share the fourth strut and are both immediately adjacent to the fourth strut; the third fenestrations have first and second opposing faces. the SMP foam substantially covers at least 80% of a first surface of the third fenestrations; (c)(i) the first and second struts rigidly connect the SMP foam, but (c)(ii) the third and fourth struts do not rigidly connect the SMP foam; in a first orientation, (d)(i) the stent has a first maximum stent outer diameter, (d)(ii) the third fenestrations have a first fenestrations length measured parallel to a major axis of the stent, and (d)(iii) the third fenestrations have a first fenestrations width measured perpendicular to the major axis of the stent and parallel to a minor axis of the stent; in a second orientation, (e)(i) the stent has a second maximum stent outer diameter that is longer than the first maximum stent outer diameter, (e)(ii) the third fenestrations have a second fenestrations length that is shorter than the first fenestrations length, and (e)(iii) the third fenestrations have a second fenestrations width that is wider than the first fenestrations width.

[0071] Thus, in some embodiments, the product may be shipped with the SMP foam already transitioned from a compressed state to a non-compressed state (eg, already plasticized).

[0072] Although some embodiments discussed herein address windows and posts, the embodiments are not limited to any one form of support structure. Metal or polymer support frameworks are viable options that can benefit from SMP foam to reduce or prevent PVL. Furthermore, the bottom half of the SMP foam can be bonded to the support structure, while the top half of the SMP foam is not. This allows the support structure (as one example) to be extended without damaging the radially compressed SMP foam.

[0073] Although the examples have dealt with the transition of SMP foams to the primary state in response to thermal stimuli, SMP foams can also be stimulated based on body heat, warm saline solution, electromagnetic stimuli via fields delivered externally or internally, light from fiber optic cables, interaction with electrical current delivered through wires in close proximity to the foam, etc.

[0074] In some embodiments, the SMP foam may be replaced with a hydrogel.

[0075] Example 2: The device of example 1, wherein in the compressed state, the first foam is radially compressed along a radius that is perpendicular to both the major axis of the stent and the minor axis of the stent.

[0076] Example 3: The device of Example 2, wherein the compressed length of the SMP foam is the length of a first foam, the length of the first foam being measured parallel to the longitudinal axis of the stent; and the expanded length of the SMP foam is the length of a second foam, the length of the first foam being substantially equal to the length of the second foam.

[0077] Example 4: The device of Example 2, wherein the first strut penetrates the SMP foam at at least one location transversely from a first surface of the SMP foam to a second surface of the SMP foam, and the first and second surfaces oppose each other.

[0078] Example 5: The device of Example 2, wherein the first strut connects to the second strut at a first junction; an axis intersects the first junction but does not contact the SMP foam; the axis is perpendicular to the major axis of the stent; and the axis is perpendicular to the minor axis of the stent.

[0079] Example 6: The apparatus of Example 2, including an adhesive connecting the SMP foam to the first and second struts.

[0080] Example 7: The apparatus of Example 6, wherein the adhesive comprises an unfoamed polyurethane coating fixedly adhered to and in direct contact with the first strut; and the SMP foam is fixedly adhered to and in direct contact with the polyurethane coating; and wherein the polyurethane coating fixedly adheres the SMP foam to the first strut.

[0081] Example 8: The device of Example 7, wherein the polyurethane coating is a cured thermoset.

[0082] Example 9: The device of Example 7, wherein the polyurethane coating is thermoplastic.

[0083] Example 10: The device described in Example 7, wherein the chemical composition of the polyurethane coating is equal to the chemical composition of the SMP foam.

[0084] Example 11: The device described in Example 10, where the polyurethane coating is an SMP.

[0085] Example 12: The device of Example 6, including an inner conduit between the valve and the SMP foam.

[0086] For example, the inner conduit can include a thermoplastic polyurethane membrane deposited on the stent struts. The SMP foam can then be adhered to the membrane with an adhesive. As noted above, the adhesive can include polyurethane. That is, one embodiment includes a polyurethane adhesive that adheres the polyurethane SMP foam to the polyurethane membrane (where the membrane is adhered to the stent).

[0087] Example 13: The apparatus of Example 2, wherein the outer conduit is made of polytetrafluoroethylene (PTFE).

[0088] Example 14: A device as described in Example 2, wherein the SMP foam is covalently bonded to iodine.

[0089] Example 15: The device of Example 14, wherein the SMP foam is poly(urethane-urea-amide).

[0090] Example 16: The apparatus of example 14, wherein the iodine is contained in triiodobenzene monomer.

[0091] Example 17: The device of Example 2, wherein the SMP foam is obtained by reaction of one or more polyols with one or more diisocyanates.

[0092] Example 18: The device of Example 2, wherein the SMP foam substantially covers a majority of a first surface of the third window but does not cover a majority of a surface of any of the first, second, fourth, and fifth windows; the third window is directly adjacent to each of the first, second, fourth, and fifth windows; and no other stent windows exist between the third window and any of the first, second, fourth, and fifth windows.

[0093] Example 19: an additional open-cell polyurethane thermoset SMP foam configured to expand in response to a thermal stimulus from a compressed secondary state to an expanded primary state; wherein the additional SMP foam covers a first side of the fourth window, the first side and second side being substantially opposed to one another; and the third strut fixedly connects the additional SMP foam; 3. The apparatus of Example 2, wherein in the first direction, the further SMP foam is in the compressed secondary state; and in the second direction, the further SMP foam is in the expanded primary state.

[0094] Example 20: The device of Example 19, wherein the SMP foam and the further SMP foam overlap one another such that axes of the SMP foam and the further SMP foam together intersect; the axes are perpendicular to the major axis of the stent; and the axes are perpendicular to the minor axis of the stent.

[0095] The device of Example 2, wherein an additional open-cell polyurethane thermoset SMP foam is configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus; wherein the additional SMP foam substantially covers a first surface of a sixth window included in the stent, the sixth window having opposing first and second surfaces; the additional SMP foam does not substantially cover the third window; the SMP foam does not substantially cover the sixth window; additional struts included in the sixth window securely connect the additional SMP foam; in the first orientation, the additional SMP foam is in the compressed secondary state; and in the second orientation, the additional SMP foam is in the expanded primary state.

[0096] Example 22: The device of Example 21, wherein the surface area of ​​the SMP foam is a first surface area; the surface area of ​​the additional foam is a second surface area; and the first surface area is at least 20% greater than the second surface area.

[0097] While Example 22 addresses the example of varying scale or size of SMP foam segments, other examples include SMP foam segments with different densities, compression, porosity, etc. For example, a higher density foam may be directly adjacent to the valve annulus while being axially sandwiched by a lower density foam, allowing the higher density foam to withstand lift forces not present in areas removed from the valve annulus.

[0098] Example 23: The device of Example 2, wherein the SMP foam comprises a monolithic SMP foam ring; the SMP foam ring is external to and surrounds the stent.

[0099] Example 24: The device of Example 2, wherein a first plane parallel to the minor axis of the stent intersects the SMP foam, the first and second struts, and the first, second, and third fenestrations; a second plane parallel to the minor axis of the stent intersects the SMP foam, the third and fourth struts, and the third, fourth, and fifth fenestrations; the first plane does not intersect either the third or fourth struts; the first plane does not intersect either the fourth or fifth fenestrations; the second plane does not intersect either the first or second struts; and the second plane does not intersect either the first or second fenestrations.

[0100] Example 25: The device of example 2, wherein the first, second, third, and fourth struts each comprise at least one of nitinol, cobalt chromium, and stainless steel.

[0101] Example 26: A device comprising: a metal scaffold comprising first, second, third, and fourth struts; a valve contained within the scaffold; an open-cell polyurethane thermoset shape memory polymer (SMP) foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus, wherein (a)(i) the first and second struts fixedly connect the SMP foam, and (a)(ii) the third and fourth struts do not fixedly connect the SMP foam; in a first orientation, (b)(i) the stent has a first maximum outer stent diameter, (b)(ii) the stent has a first stent length measured parallel to a longitudinal axis of the stent, and (b)(iii) the SMP foam is in the compressed secondary state; and in a second orientation, (c)(i) the stent has a second maximum outer stent diameter that is longer than the first maximum outer stent diameter. (c)(ii) the stent has a second stent length that is shorter than the first stent length; and (c)(iii) the SMP foam is in the expanded primary state; and in response to the first and second struts rigidly connecting the SMP foam and the third and fourth struts not rigidly connecting the SMP foam, the SMP foam is configured to move dependently on the first and second struts but independent of the third and fourth struts when the device transitions from the first orientation to the second orientation; a first plane perpendicular to the longitudinal axis of the stent intersects the SMP foam and the first and second struts; a second plane perpendicular to the longitudinal axis of the stent intersects the SMP foam and the third and fourth struts; the first plane does not intersect either the third or fourth struts; and the second plane does not intersect either the first or second struts.

[0102] Example 1a: A device comprising: a structural support scaffold comprising first, second, third, and fourth struts; a valve contained within the scaffold; an open-cell polyurethane thermoset shape memory polymer (SMP) foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus, wherein: (a)(i) the first and second struts rigidly connect the SMP foam, and (a)(ii) the third and fourth struts do not rigidly connect the SMP foam; in a first orientation, (b)(i) the stent has a first maximum outer stent diameter, (b)(ii) the stent has a first stent length measured parallel to a longitudinal axis of the stent, and (b)(iii) the SMP foam is in the compressed secondary state; and in a second orientation, (c)(i) the stent has a second maximum outer stent diameter that is longer than the first maximum outer stent diameter. (c)(ii) the stent has a second stent length that is shorter than the first stent length; and (c)(iii) the SMP foam is in the expanded primary state; responsive to the first and second struts rigidly connecting the SMP foam and the third and fourth struts not rigidly connecting the SMP foam, the SMP foam is configured to move dependently on the first and second struts but independent of the third and fourth struts when the device transitions from the first orientation to the second orientation; a first plane perpendicular to the longitudinal axis of the stent intersects the SMP foam and the first and second struts; a second plane perpendicular to the longitudinal axis of the stent intersects the SMP foam and the third and fourth struts; the first plane does not intersect either the third or fourth struts; and the second plane does not intersect either the first or second struts.

[0103] Therefore, not all scaffolds are metal: some may be formed from polymers, etc.

[0104] Example 2a: The apparatus of Example 1a, wherein an adhesive is in direct contact with the first and second struts and the SMP foam, directly adhering the SMP foam to each of the first and second struts; but neither the third nor fourth struts are in direct contact with adhesive, which is in direct contact with the SMP foam.

[0105] Example 3a: The device of Example 1a, including a membrane in contact with the first and second struts, wherein a location within the upper half of the SMP foam is directly adhered to the membrane via an adhesive that is in direct contact with the membrane and the SMP foam; and a lower half of the SMP foam is not directly adhered to the membrane via any adhesive and is configured to slide on the membrane when the device is moved from a first orientation to a second orientation.

[0106] Example 4a: The device of any one of Examples 1a-3a, wherein in the compressed state, the first foam is radially compressed along a radius that is perpendicular to both the major axis of the stent and the minor axis of the stent.

[0107] Example 5a: The SMP foam is a first foam in a compressed state, the length of the first foam being measured parallel to the longitudinal axis of the stent; the length of the SMP foam in an expanded state is the length of a second foam; and the length of the first foam is substantially equal to the length of the second foam. The device described in Example 4a.

[0108] Example 6a: The device of Example 4a, wherein the first strut penetrates the SMP foam at at least one location transversely from a first surface of the SMP foam to a second surface of the SMP foam, and the first and second surfaces oppose each other.

[0109] Example 7a: The device of Example 4a, wherein the first strut connects to the second strut at a first junction; an axis intersects the first junction but does not contact the SMP foam; the axis is perpendicular to the major axis of the stent; and the axis is perpendicular to the minor axis of the stent.

[0110] Example 8a: The device of Example 1a, including an adhesive connecting the SMP foam to the first and second struts.

[0111] Example 9a: The apparatus of any of Examples 2a-8a, wherein the adhesive includes an unfoamed polyurethane coating fixedly bonded to and in direct contact with the first strut; and the SMP foam is fixedly bonded to and in direct contact with the polyurethane coating; and wherein the polyurethane coating fixedly bonds the SMP foam to the first strut.

[0112] Example 10a: The device of Example 9a, wherein the polyurethane coating is a cured thermoset.

[0113] Example 11a: A device as described in Example 9a, where the polyurethane coating is thermoplastic.

[0114] Example 12a: The device of Example 9a, wherein the chemical composition of the polyurethane coating is equal to the chemical composition of the SMP foam.

[0115] Example 13a: The device of Example 12a, wherein the polyurethane coating is an SMP.

[0116] Example 14a: The device of Example 4a, including an inner conduit between the valve and the SMP foam.

[0117] For example, the inner conduit can include a thermoplastic polyurethane membrane deposited on the stent struts. The SMP foam can then be adhered to the membrane with an adhesive. As noted above, the adhesive can include polyurethane. That is, one embodiment includes a polyurethane adhesive that adheres the polyurethane SMP foam to the polyurethane membrane (where the membrane is adhered to the stent).

[0118] Example 15a: The apparatus of Example 4a, wherein the outer conduit comprises polytetrafluoroethylene (PTFE).

[0119] Example 16a: A device as described in Example 4a, wherein the SMP foam is covalently bonded to iodine.

[0120] Example 17a: The device of Example 16a, wherein the SMP foam is poly(urethane-urea-amide).

[0121] Example 18a: The apparatus of Example 16a, wherein the iodine is contained in triiodobenzene monomer.

[0122] Example 19a: The device of Example 4a, wherein the SMP foam is obtained by reaction of one or more polyols with one or more diisocyanates.

[0123] Example 20a: The device of Example 4a, wherein the SMP foam substantially covers a majority of a first surface of the third window but does not cover a majority of a surface of any of the first, second, fourth, and fifth windows; the third window is directly adjacent to each of the first, second, fourth, and fifth windows; and no other stent windows exist between the third window and any of the first, second, fourth, and fifth windows.

[0124] Example 21a: The device of Example 21a, further comprising an open-cell polyurethane thermoset SMP foam configured to expand in response to a thermal stimulus from a compressed secondary state to an expanded primary state; wherein the further SMP foam covers a first side of the fourth window, the first side and second side being substantially opposed to one another; the third strut fixedly connects the further SMP foam; in the first direction, the further SMP foam is in the compressed secondary state; and in the second direction, the further SMP foam is in the expanded primary state.

[0125] Example 22a: The device of Example 21a, wherein the SMP foam and the further SMP foam overlap one another such that axes of the SMP foam and the further SMP foam together intersect; the axes are perpendicular to the major axis of the stent; and the axes are perpendicular to the minor axis of the stent.

[0126] Example 23a is the device of Example 4a, wherein an additional open-cell polyurethane thermoset SMP foam is configured to expand in response to a thermal stimulus from a compressed secondary state to an expanded primary state; wherein the additional SMP foam substantially covers a first surface of a sixth window included in the stent, the sixth window having opposing first and second surfaces; the additional SMP foam does not substantially cover the third window; the SMP foam does not substantially cover the sixth window; additional struts included in the sixth window securely connect the additional SMP foam; in the first orientation, the additional SMP foam is in the compressed secondary state; and in the second orientation, the additional SMP foam is in the expanded primary state.

[0127] Example 24a: The apparatus of Example 23a, wherein the surface area of ​​the SMP foam is a first surface area; the surface area of ​​the additional foam is a second surface area; and the first surface area is at least 20% greater than the second surface area.

[0128] Example 25a: The device of Example 4a, wherein the SMP foam comprises a monolithic SMP foam ring; the SMP foam ring is external to and surrounds the stent.

[0129] Example 26a: The device of Example 4a, wherein the first, second, third, and fourth struts each comprise at least one of nitinol, cobalt chromium, and stainless steel.

[0130] The foregoing description of embodiments of the present invention has been presented for purposes of illustration and description. The precise forms disclosed are not exhaustive, and the present invention is not limited thereto. The present specification and claims include terms used for descriptive purposes only, such as left, right, top, bottom, on top of, below, upper, bottom, first, second, etc., but should not be construed as limiting. For example, terms indicating a relative vertical position refer to a situation in which a side of a substrate is the "top" surface of that substrate, and the substrate may actually be oriented in any direction, such that the "top" side of the substrate may be lower than the "bottom" side of a standard frame of reference and still be within the meaning of the term "top." The term "above" in this specification (and in the claims) does not imply that a first layer "above" a second layer is directly on or in direct contact with the second layer, unless otherwise specified; a third layer or other structure may exist between the first and second layers. The device or product embodiments described herein may be manufactured, used, or shipped in numerous configurations and orientations. Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings. Those skilled in the art will recognize various equivalent combinations and substitutions for the various components shown in the figures. Accordingly, it is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

Claims

1. a valve support structure comprising at least one of a metal or a polymer; a valve contained within the valve support structure; and Polyurethane shape memory polymer (SMP) foam; 1. An apparatus comprising: (a)(i) a first half of the SMP foam is fixedly bonded to a first portion of the valve support structure; and (a)(ii) no portion of a second half of the SMP foam is fixedly bonded to a second portion of the valve support structure; In a first direction, (b)(i) the valve support structure has a first maximum outer diameter, and (b)(ii) the valve support structure has a first length measured parallel to a longitudinal axis of the valve support structure; In a second orientation, (c)(i) the valve support structure has a second maximum outer diameter that is greater than the first maximum outer diameter, and (c)(ii) the valve support structure has a second length that is less than the first length; a first half of the SMP foam is fixedly coupled to the first portion of the valve support structure and no portion of the second half of the SMP foam is fixedly coupled to the second portion of the valve support structure, such that when the device moves from the first orientation to the second orientation, the SMP foam moves dependently on the first portion of the valve support structure but independent of the second portion of the valve support structure; a first plane perpendicular to a longitudinal axis of the valve support structure intersects the SMP foam and the first portion of the valve support structure; a second plane perpendicular to the longitudinal axis of the valve support structure intersects the SMP foam and the second portion of the valve support structure; the first plane does not intersect the second portion of the valve support structure; and the second plane does not intersect the first portion of the valve support structure. Device.

2. The device of claim 1 comprising a membrane.

3. The device of claim 2 , wherein a membrane is between the valve and the SMP foam.

4. The device of claim 2 , wherein a membrane is between the valve support structure and the SMP foam.

5. The device of any one of claims 2 to 4, wherein the membrane comprises a polymer.

6. The device of any one of claims 2 to 4, wherein the membrane comprises a skirt.

7. The apparatus of claim 6 wherein a skirt is folded onto the SMP foam.

8. 8. The device of any one of claims 2 to 7, wherein the SMP foam is fixedly adhered to the membrane with an adhesive.

9. 9. The device of any one of claims 2 to 8, wherein a membrane fixedly bonds the first half of the SMP foam to the first portion of the valve support structure.

10. The apparatus of any one of claims 1 to 9, wherein the SMP foam comprises a monolithic SMP foam ring.

11. 11. The device of claim 10, wherein the monolithic SMP foam ring includes folds, pleats, or a combination thereof.

12. 12. The device of claim 10 or 11, wherein a monolithic SMP foam ring surrounds the valve.

13. 13. The apparatus of any one of claims 1 to 12, comprising a further polyurethane SMP foam overlying the SMP foam.

14. 13. The device of claim 1, comprising a plurality of the SMP foam bodies, the plurality of SMP foam bodies including the SMP foam body, and the plurality of SMP foam bodies surrounding a valve.

15. An apparatus according to any preceding claim, comprising the valve support structure, a valve, and a conduit comprising the SMP foam.

16. 16. The device of any one of claims 1 to 15, wherein a second half of the SMP foam contacts a second portion of the valve support structure.

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