Systems, devices, and methods for a replacement valve with a monolithic stent structure

Abstract

Embodiments of this specification relate to a replacement valve comprising a double-walled folded stent structure having an inner wall that provides a lumen, and a valve structure attached to the stent structure. The inner wall is spaced from an outer wall configured to seal and / or secure the anatomical structure of the surrounding native valve, but is continuous with the inner wall via a transition wall. The transition wall can result from folding, inverting, or everting of a single tubular structure into a double-walled single-piece tubular stent structure. The stent structure is configured to be reversibly folded into a collapsed configuration exhibiting a reduced diameter or cross-sectional profile for loading into a catheter and delivery to a target anatomical site and an expanded configuration.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 350,207, filed on June 8, 2022, which is hereby incorporated by reference in its entirety under 35 U.S.C. § 119(e).

Background Art

[0002] This patent application generally relates to the treatment of valvular heart disease, and more specifically, to methods and devices for minimally invasive tricuspid valve replacement.

[0003] Valvular heart disease has a prevalence of 2 - 3% worldwide and an increasing prevalence in the elderly population, imposing a significant burden on patients and the healthcare system. Valvular heart disease typically results from cardiovascular causes such as myocardial infarction and heart failure, but can also result from a variety of etiologies including autoimmune, infectious, and degenerative causes. The etiology of valvular heart disease also varies depending on the valve affected. For example, tricuspid regurgitation can be caused by congenital diseases, infective endocarditis or rheumatic fever, iatrogenic events such as damage from a pacemaker wire or endomyocardial biopsy, Marfan syndrome, and other problems.

Summary of the Invention

[0004] Further growth of transcatheter tricuspid valve therapy has challenges due to the anatomical structure and physiology of the tricuspid valve, compared to more established transcatheter aortic and mitral valve therapies. For example, the anatomical structure of the tricuspid valve and its surrounding area is not stiffer than that of the aortic and mitral valves and their surrounding areas, making it difficult to fix a replacement valve to the tricuspid valve.

[0005] To address these issues, the embodiments described herein are directed to a prosthetic heart valve comprising a single-piece, folded, double-wall stent having a valve structure (e.g., a leaflet valve) attached to the lumen of the stent cover and the stent. The double-wall stent structure separates or reduces the influence of the geometry of the holding structure on the geometry of the valve support. This includes external forces acting through the valve annulus during the cardiac cycle, as well as the effects of a non-circular valve annulus shape. The double-wall stent structure also enables the valve support to have a different size and shape than the outer valve annulus support without the need for the valve support to expand or deform relative to the native anatomical structure, or without the need to at least partially separate the effects of expansion of the outer valve annulus support from the native anatomical structure. The single-piece design can also enable greater structural integrity by reducing the concentration of forces between joined, welded, or mechanically connected support components and / or the complexity associated with their on-site attachment.

[0006] In an embodiment, a replacement heart valve is disclosed. The replacement heart valve comprises a single-piece stent structure. The stent structure comprises a folded configuration and an expanded configuration. The stent structure also comprises an outer wall having an enlarged diameter region and a reduced diameter region. Further, the stent structure comprises an inner wall defining a lumen and a transition wall between the outer wall and the inner wall. The replacement heart valve also comprises a valve structure disposed within the lumen of the inner wall. The single-piece stent structure further comprises a plurality of longitudinally extending struts and a plurality of laterally extending struts integrally formed, each longitudinally extending strut being continuously disposed along a portion of the inner wall, the transition wall, and the outer wall. The outer wall may have a generally flare shape or a frustoconical shape, and the posterior diameter is located at one end opposite the transition wall. The inner wall may have a generally cylindrical shape. In an embodiment comprising a replacement tricuspid valve, the longitudinally extending struts may be provided in a multiple of 3, for example a total of 3, 6, 9, or 12 longitudinally extending struts. In some variations, the longitudinally extending struts extend along the entire length of the inner wall, as well as the length of the transition wall and the entire length of the outer wall. However, in other variations, the longitudinally extending struts only partially extend along the length of the outer wall. The length of the longitudinally extending strut segments in the outer wall may be shorter than, the same as, or longer than the length of the longitudinally extending strut segments in the inner wall. The inner wall and the transition wall may comprise a non-shortened configuration in the longitudinal direction, while the outer wall may be partially shortened and non-shortened in the longitudinal direction, the non-shortened portion being continuous with the transition wall and the shortened portion being located at the free end of the outer wall. Radially extending anchor struts may also be provided. The anchor struts may be curved radially outward and may be located in the shortened portion of the outer wall.

[0007] In one embodiment, a prosthetic heart valve is provided that includes a monolithic stent structure having a folded configuration and an expanded configuration, an outer wall having an enlarged diameter region and a reduced diameter region, an inner wall defining a lumen, a transition wall between the outer wall and the inner wall, and a valve structure disposed within the lumen of the inner wall. The monolithic stent structure further includes a plurality of longitudinally extending struts and a plurality of laterally extending struts integrally formed therewith. Each longitudinally extending strut is continuously disposed along a portion of the inner wall, the transition wall, and the outer wall. The ratio of the axial length of the portion of the outer wall having none of the plurality of longitudinally extending struts to the axial length of the portion of the outer wall having at least a portion of the plurality of longitudinally extending struts is in the range of 1:1 to 1:1.5. The valve may be a tricuspid prosthetic valve. The transition wall may be downstream of the enlarged diameter region. The outer wall may include a first region extending from the transition wall and a second region extending from the open end of the outer wall. The first region includes a plurality of longitudinally extending struts, and the second region does not include a plurality of longitudinally extending struts. The first region may include at least one of the plurality of laterally extending struts, the second region may include at least one of the plurality of laterally extending struts, and at least one of the plurality of laterally extending struts in the first region exhibits a strut configuration different from at least one of the plurality of laterally extending struts in the second region. At least one of the plurality of laterally extending struts in the first region includes a generally straight leg with a deformation near the end of each leg, and at least one of the plurality of laterally extending struts in the second region includes a leg exhibiting a generally S-shaped or combined concave / convex shape. At least a portion of the first region of the outer wall may be configured to be disposed in the ventricle of the heart, and at least a portion of the second region of the outer wall may be configured to be disposed in the atrium of the heart. The second region of the outer wall may be configured to be more flexible than the first region of the outer wall. The outer wall may include a plurality of returns extending therefrom. The outer wall may include a first region extending from the transition wall and a second region extending from the open end of the outer wall. The first region includes a plurality of longitudinally extending struts, and the second region does not include a plurality of longitudinally extending struts. The plurality of returns extend from the second region of the outer wall. The plurality of returns may be oriented toward the outer opening of the outer wall relative to the transition wall. The plurality of longitudinally extending struts and the plurality of laterally extending struts may comprise nitinol.The replacement heart valve may further include skirt material disposed on at least a portion of the outer wall, at least a portion of the inner wall, and at least a portion of the transition wall. The skirt material can comprise a first material and a second material different from the first material. The first material may comprise a woven material, and the second material may comprise a knit material. The woven material may be such that at least a portion of the inner wall and at least a portion of the outer wall extend from an outer opening of the outer wall, and a portion of the woven material extends and is disposed between the inner wall and the outer wall. The knit material is disposed on at least a portion of the transition wall and a portion of the outer wall extending from the transition wall. A portion of the woven material extending between the inner wall and the outer wall may extend across the outer opening. A portion of the woven material extending between the inner wall and the outer wall extends across an intermediate position spaced from the outer opening. The outer wall can comprise a plurality of returns extending therefrom, and the skirt material can comprise a plurality of openings formed therein, each of the plurality of openings being configured to receive one of the plurality of returns. The skirt material can comprise one or more lead openings configured to allow one or more conductors to pass therethrough. The ratio of the axial length of a portion of the outer wall having none of the plurality of longitudinal struts to the axial length of a portion of the outer wall having at least some of the plurality of longitudinal struts can be in the range of 1:1.0 to 1:1.4. The inflow angle between the inlet of the outer wall and the inlet of the inner wall can be in the range of 5 degrees to 35 degrees, or in the range of 25 degrees to 35 degrees. The ratio of the diameter of the inner wall to the diameter of the outer wall at the end point of at least one of the plurality of longitudinal struts may be in the range of 1:1 to 1:2. The ratio between the diameter of the inner wall and the diameter of the outer wall at the end point of at least one of the plurality of longitudinal struts can be in the range of 1.4 to 1.6, the replacement heart valve according to claim 24. The transition wall can have an average radius of curvature in the range of about 1 mm to 5 mm, or about 1.5 mm to 3 mm. The ratio of the axial dimension of the combined outer wall and transition wall to the axial dimension of the combined inner wall and transition wall can be in the range of about 1:1 to 1:1.5, or in the range of 1.1 to 1.3. The ratio of the axial dimension of the outer wall to the axial dimension of the inner wall can be in the range of about 1:05 to 1:1.4, or about 1.1 to 1.3.The ratio of the diameter of the outer wall having at least one end of a plurality of vertical struts to the maximum diameter of the outer wall may be in the range of 1:1 to 1:1.5, or 1:1.2 to 1:1.4.

Brief Description of the Drawings

[0008]

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Figure 7B

DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments herein relate to a replacement valve comprising a double-walled folded stent structure having an inner wall that provides a lumen and a valve structure attached to the stent structure. The inner wall is spaced from an outer wall configured to seal and / or secure the surrounding native valve's anatomical structure, but is continuous with the inner wall via a transition wall. The transition wall can result from the folding, inflection, or eversion of a single tubular structure's double wall into a unitary tubular stent structure. The stent structure is configured to be reversibly folded into a collapsed configuration that exhibits a reduced diameter or cross-sectional shape for loading within a catheter and delivery to a target anatomical site and an expanded configuration.

[0010] In a further embodiment, the outer wall of the stent structure may be shaped to have an enlarged diameter region and a reduced diameter region downstream of the enlarged diameter region. The enlarged diameter region and the reduced diameter region can facilitate the fixation of the stent structure across a desired anatomical site. The reduced diameter region is configured to expand against the native valve tip and / or anatomical opening, while the enlarged diameter region provides mechanical interference or resistance to displacement. The mechanical interference and / or frictional interference can secure the stent structure to the anatomical structure and form a seal that prevents fluid flow between the stent structure and the anatomical structure. In an embodiment, the outer wall does not comprise an additional enlarged diameter region downstream of the reduced diameter region because the additional enlarged diameter region can interfere with the chordae of the tricuspid valve or other anatomical structures.

[0011] Although some of the exemplary embodiments described herein are directed to transcatheter replacement of the tricuspid valve, the components and structures herein are not limited to any particular valve or delivery method and can be adapted for implantation in tricuspid, pulmonary, aortic valve locations, and non-cardiac locations (e.g., the aorta, venous or cerebrospinal fluid systems, or natural or artificial conduits, ducts or shunts). As used herein, spatial references to a first end or lower end of a component may also be characterized by the anatomical space the component occupies and / or the relative direction of fluid flow. For example, the first end or lower end of a stent structure of a replacement tricuspid valve may also be referred to as the ventricular end or downstream end of the valve, and the opposite end (e.g., the second end or upper end) may be referred to as the atrial end or upstream end of the valve.

[0012] An exemplary embodiment of a stent structure 100 is shown in Figures 1A-1E, with the stent structure 100 in its expanded configuration. For illustrative purposes, the latter portions of the stent structure 100 shown in Figures 1A, 1C, and 1D have been omitted to simplify the depiction of the stent structure. The stent structure 100 comprises an inner lumen 102 formed by an inner wall 104. An outer wall 106 is radially spaced from the inner wall 104 via a transition wall 108 to form an annular cavity 110. The stent structure 100 has a first closed end 112 located at the transition wall 108 and a second open end 114 of the outer wall 106, with the annular cavity 110 being open and accessible. The stent structure 100 can exhibit a unitary structure (e.g., formed from a single piece) that provides the stent structure 100 with structural integrity that better redistributes forces acting on the stent structure 100, with fewer force concentrations typically found in stent structures comprising multiple components.

[0013] The inner lumen 102 comprises a first opening 116 surrounded by a transition wall 108 and a second opening 118 at the second opening end 114 of the stent structure 100. The longitudinal axis 120 of the inner lumen 102 typically coincides with the central axis of the stent structure 100, although in some variations, the inner lumen 102 may be disposed eccentrically with respect to the outer wall 106 of the stent structure 100. The inner lumen 102 typically has a circular cross-sectional shape with a generally cylindrical shape between the first opening 116 and the second opening 118, as shown in FIGS. 1A - 1C. In other examples, the inner lumen 102 may comprise a frustoconical, elliptical or polygonal shape. In some variations, the stent structure 100 may comprise inner lumens in which the sizes and / or shapes of the first opening 116 and the second opening 118 may differ. Referring to FIG. 1F, the length 150 of the inner lumen 102 can be measured from the first opening 116 to the second opening 118 and can be in the range of 10 mm to 50 mm, 15 mm to 40 mm, 20 mm to 25 mm, 15 mm to 20 mm, 17.5 mm to 22.5 mm, 20 mm to 25 mm, 22.5 mm to 27.5 mm, 25 mm to 30 mm, 27.5 mm to 32.5 mm, 30 mm to 35 mm, 32.5 mm to 27.5 mm, or about 35 mm to 40 mm, or 22 mm to 27 mm, and the diameter 152 or the maximum cross-sectional dimension of the inner lumen 102 can be in the range of 15 mm to 40 mm, 15 mm to 25 mm, 20 mm to 30 mm, 25 mm to 35 mm, or 27 mm to 32 mm. In embodiments where the inner lumen 102 has a non-cylindrical shape, the difference in diameter or cross-sectional dimension between the first opening 116 and the second opening 118 can be in the range of 1 mm to 10 mm, 1 mm to 5 mm, or 1 mm to 3 mm.

[0014] Maximum length L IIt can be selected based on the size of the anatomical structure and is selected to be large enough to allow the valve structure (described in more detail in relation to FIG. 6) to function within the lumen 102. However, in some variations, in order to more easily insert the stent structure 100 into the desired anatomical structure, when the stent structure 100 is in a folded configuration, it may generally be desirable to minimize the maximum length 150 to limit the length of the stent structure 100. Also, since the portion of the stent structure 100 disposed in the ventricle may interfere with the ventricle, it may be desirable to minimize the maximum length 150 to reduce the length of the stent structure 100 disposed in the ventricle.

[0015] The positions of the first opening 116 and the second opening 118 of the lumen 102 relative to the entire stent structure 100 can also vary. In some variations, the first opening 116 of the lumen 102 may be recessed relative to the first end 112, as shown in FIGS. 1A and 1E. In other examples, the first opening 116 may be substantially flush with the first end 112 of the transition wall 108 of the stent structure 100. The position of the first opening 116 may also be characterized as recessed, flush, or protruding relative to the longitudinal position of the inner wall 104 or the inner joint 122 between the lumen 102 and the transition wall 108, or relative to the outer joint 124 between the transition wall 108 and the outer wall 106. Similarly, the second opening 118 of the lumen 102 may be characterized as recessed, flush, or protruding relative to the longitudinal position of the outer opening 126 of the outer wall 106. For example, the second opening 118 of the lumen 102 has an offset or protruding position relative to the outer opening 126 of the outer wall 106. In some variations, the lumen 102 may have a smaller or shorter outer wall 106 to correspond to the anatomical structure of a smaller-sized native valve. In a preferred variation, it may protrude relative to the outer opening 126 of the outer wall 106. However, the size of the lumen 102 may remain relatively the same between different size variations in order to provide a consistent valve shape and / or hemodynamic characteristics.

[0016] The transition wall 108 of the stent structure 100 has a generally annular and rounded shape (e.g., concave or convex shape) surrounding the inner lumen 102 in the expanded configuration, but in other variations, it may have different shapes and / or surface angles. For example, in cross-section, the transition wall 108 can have a rounded (e.g., semi-circular) shape between the inner junction 122 and the outer junction 124, but in other variations, it can have a generally straight shape (e.g., showing an angle substantially orthogonal to the longitudinal axis 120 of the inner lumen 102). Referring to FIG. 1E, the transition wall 108 of the stent structure 100 may exhibit an average radius of curvature R T . The average radius of curvature R T can range from 0.5 mm to 1.5 mm, 1 mm to 2 mm, 1.5 mm to 2.5 mm, 1.5 mm to 2 mm, 1.5 mm to 3 mm, 2 mm to 3 mm, 2.5 mm to 3.5 mm, 1 mm to 5 mm, or 3 mm to 4 mm.

[0017] Referring to FIG. 1F, the maximum diameter 160 of the outer wall 106 in the maximum expansion configuration without the return 146, which is also the diameter of the inlet or the outer opening of the outer wall 106, may be in the range of 40 mm to 80 mm, 45 mm to 70 mm, 50 mm to 70 mm, 55 mm to 65 mm, or 58 mm to 62 mm. Including the distal tip of the return 146, the maximum diameter 162 in the maximum expansion configuration of the outer wall 106 may be in the range of 40 mm to 80 mm, 50 mm to 75 mm, 55 mm to 65 mm, 60 mm to 65 mm, or 60 mm to 70 mm. The minimum diameter 164 of the outer wall 106 in the maximum expansion configuration, which may also be the diameter at the junction of the outer wall 106 and the transition wall 108, may be in the range of 25 mm to 60 mm, 30 mm to 50 mm, 30 mm to 45 mm, or 35 mm to 40 mm. Referring back to FIG. 1E, the diameter 166 of the outer wall 106 at the junction between the first region 128 and the second region 130 may be the inflection point of the concave-convex shape of the outer wall 106 and may be in the range of 25 mm to 60 mm, 30 mm to 55 mm, 35 mm to 50 mm, 40 mm to 50 mm, 45 to 50 mm, 40 mm to 45 mm, or 42 to 47 mm. The axial length 168 of the outer wall 106 may be in the range of 25 mm to 30 mm, 27 mm to 32 mm, 24 mm to 35 mm, or 26 mm to 34 mm. The axial length 174 of the transition wall 108 may be in the range of 2 mm to 3 mm, 2.0 mm to 2.5 mm, 1 mm to 5 mm, 2 mm to 4 mm, or 2 mm to 8 mm. However, in other variations, the outer wall 106 can have a wall configuration with a substantially straight cross-section, i.e., a cylindrical or frustoconical shape.

[0018] Referring to FIG. 1G, the axial dimension of the first region 128 of the outer wall 106 and the axial dimension of the second region 130 of the outer wall 106 can vary according to the desired relative implantation level of the valve 100 with respect to the valve ring. The axial dimension of the first region 128 of the outer wall 106 when measured parallel to the longitudinal axis of the valve 100 can be in the range of 6 mm to 20 mm, 8 mm to 18 mm, 10 mm to 15 mm, or 12 mm to 15 mm. The axial dimension of the second region 130 of the outer wall 106 when measured parallel to the longitudinal axis of the valve 100 can be in the range of 16 mm to 20 mm, 15 mm to 20 mm, 12 mm to 24 mm, or 10 mm to 28 mm. The ratio of the axial length of the second portion, or a part of the outer wall having no plurality of longitudinal struts, and the axial length of the first portion, or a part of the outer wall having at least some of the plurality of longitudinal struts, is in the range of 1:1 to 1:1.5, 1:1.2 to 1:1.4, or 1:1.3 to 1:1.4. The ratio of the axial dimension of the combined inner wall 104 and the transition wall 108 to the axial dimension of the combined outer wall 106 and the transition wall 108 can be in the range of about 1:1 to 1:1.5, 1:05 to 1:1.4, 1:1.1 to 1:1.2, or 1:1.15 to 1.20, or 1:1.2 to 1:1.3. The relative difference in the axial dimensions between the outer wall 106 and the inner wall can be, for example, in the range of -5 mm to +15 mm, -2 mm to +12 mm, 0 mm to +8 mm, +1 mm to +5 mm, or +2 mm to +4 mm. The ratio of the wall length of the inner wall 104 to the outer wall 106 (excluding the transition wall 108) can be, for example, in the range of 1:0.8 to 1:2, 1:1 to 1:1.8, 1:1 to 1:1.5, 1:1.1 to 1:1.4, 1:1.1 to 1:1.3, 1:1.2 to 1:1.4. The ratio of the diameter 166 of the outer wall 106 to the maximum diameter 160 of the outer wall 106 at the joint of the first and second portions of the outer wall 106 can be in the range of 1:1 within 1:1.5, 1:1.2 to 1:1.4, 1:1.3 to 1:1.4, or 1:1.2 to 1:1.3.

[0019] Referring to FIG. 1H, the inlet or inflow angle formed by the opening 126 of the outer wall 106 and the inlet opening 118 of the inner wall 104, or the longitudinal axis 120 of the stent 100, may be in the range of 15 degrees to 20 degrees, 16 degrees to 20 degrees, 14 degrees to 22 degrees, 16 degrees to 19 degrees, 5 degrees to 35 degrees, 10 degrees to 25 degrees, 12 degrees to 25 degrees, 20 degrees to 30 degrees, 25 degrees to 35 degrees, or 25 degrees to 30 degrees. In the embodiment shown in FIG. 1E where the cross-sectional configuration of the outer wall 106 is non-linear, the inflow angle of the outer wall 106 may be defined by the second region 130 of the outer wall 106, for example, from the longitudinal midpoint or inflection point of the outer wall 106 to the lip or opening of the outer wall 106. In some variations, it may be beneficial for the second region 130 of the outer wall 106 to have a concave configuration with respect to the inner wall 104 such that the immediate region of the outer wall 106 around the opening 126 is oriented relatively closer to the longitudinal axis 120 than in a lateral orientation with respect to the longitudinal axis 120. Referring to FIG. 1I, the axial length difference 172 between the opening 126 of the outer wall 106 and the inlet opening 118 of the inner wall 104 may be 4 mm to 6 mm, 4 mm to 5 mm, 4 mm to 8 mm, or 3 mm to 6 mm. Returning to FIG. 1F and referring, the ratio of the diameter 152 of the inner wall 104 to the diameter 166 of the outer wall 106 at the junction of the first portion 128 and the second portion 130 of the outer wall 106 (or the end of the longitudinal strut 154) can be in the range of 1:1 to 1:2, 1:1.4 to 1:1.6, 1:1.5 to 1:1.6, 1:1.3 to 1:1.7, or 1:1.2 to 1:1.8. The ratio of the diameter 152 of the inner wall 104 to the maximum diameter 160 of the outer wall can be, for example, in the range of 1:1.5 to 1:3, 1:1.7 to 1.2.7, 1:1.8 to 1:2.5, 1:1.9 to 1:2.2, or 1.9 to 1:2.1.

[0020] As described above, in some embodiments, the outer wall 106 of the stent structure 100 has a non-cylindrical shape when in the expanded configuration. This can include a flared or frustoconical shape. The outer wall 106 may comprise a first region 128 that is continuous with the transition wall 108 and a second region 130 that forms the outer opening 126. The first region 128 may exhibit a concave curvature, and the second region 130 may exhibit a convex curvature relative to the exterior of the stent structure 100 adjacent the outer wall 106 (e.g., a location not within the lumen 102 or the annular cavity 110). The first region 128 may comprise a reduced-diameter region of the stent structure 100, thereby enabling at least a portion of the first region 128 to expand against the native valve leaflets and / or anatomical opening. The reduced-diameter region of the stent structure 100 is at or extends from a portion of the outer wall 106 at or near the outer junction 124 that can prevent or at least inhibit the stent structure 100 from interfering with the anatomical structure downstream of the outer junction 124. The second region 130 may comprise an enlarged-diameter region of the stent structure 100, thereby enabling at least a portion of the second region 130 to provide mechanical interference or resistance to displacement. The enlarged-diameter region of the stent structure 100 may be at or extend from a portion of the outer wall 106 at or near the outer opening 126. In one example, the second region 130 can be used to form an atrial seal that secures the stent structure 100 within the atrium above the tricuspid valve and prevents or at least inhibits retrograde blood flow from the ventricle to the atrium. In one example, the boundary between the first region 128 and the second region 130 may be at or near the nominal or expected position of the valve annulus of a valve such as the tricuspid valve annulus.

[0021] In an embodiment, as shown in FIG. 1E, the first region 128 may exhibit a first mean radius of curvature R1, and the second region 130 may exhibit a second mean radius of curvature R2. The mean radii of curvature R1 and R2 can be independently selected to be 20 mm to 30 mm, 25 mm to 35 mm, 30 mm to 40 mm, 35 mm to 45 mm, 40 mm to 50 mm, 45 mm to 55 mm, 50 mm to 60 mm, 55 mm to 65 mm, or 60 mm to 70 mm. In an embodiment, at least one of the first region 128 or the second region 130 may be substantially linear.

[0022] The mean radius of curvature of the stent structure 100 may be used to define the geometric shape of the stent in the expanded configuration, but also affects the geometric shape of the stent in the delivery configuration or the folded configuration (shown in FIG. 7A) of the stent. A region or segment of the stent may be configured with a smaller mean radius of curvature to facilitate folding of the stent at that region or segment when the stent is folded for the folded configuration. A region of a segment of the stent may be configured with a larger mean radius of curvature to facilitate correction of that region or segment for the folded configuration. For example, in the stent structure 100, a relatively small radius of curvature R T facilitates folding or crimping of the stent structure around the transition wall 108, while the larger radii of curvature R1 and R2 facilitate flattening of the first region 128 and the second region 130, respectively, during delivery or loading of the device into the delivery system.

[0023] The non-cylindrical configuration of the outer wall 106 can enable the outer wall 106 to exhibit a greater shortening than the inner wall 104 when the outer wall 106 transitions from a relatively linear orientation in the folded configuration to the concave-convex orientation in the expanded configuration. In some variations, the longitudinal shift during the expansion of a portion of the reduced-diameter region of the outer wall 106 or the first region 128 adjacent thereto (e.g., within 10 mm, within 5 mm, or within 3 mm) may be less than 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm. In some variations, the longitudinal shift during the expansion of a portion of the enlarged-diameter region of the outer wall 106 or the second region 130 adjacent thereto (e.g., within 10 mm, within 5 mm, or within 3 mm) may be greater than 5 mm, 10 mm, 15 mm, or 20 mm.

[0024] It should be noted that the general funnel-shaped shape (e.g., non-hourglass shape) of the outer wall 106 formed by the first region 128 and the second region 130 can facilitate the attachment of the stent to an anatomical structure that does not exist in a plane, such as a tricuspid valve. For example, an outer wall showing an hourglass shape can be used to fix a stent to an anatomical structure in a plane, such as a mitral valve. However, fixing a stent showing an hourglass shape to a non-planar anatomical structure may cause the stent to tilt, which may in turn cause the stent to interfere with adjacent anatomical structures. On the other hand, the funnel-shaped shape of the outer wall 106 is considered not to exhibit such problems.

[0025] The stent structure disclosed herein further comprises a plurality of integrally formed stent strut segments, as shown in FIGS. 1A-1D. Some struts can be characterized as longitudinal strut segments 132 or transverse strut segments 134. The longitudinal strut segments 132 generally lie within a radial plane 135 (shown schematically as a dashed box in FIG. 1E) in which the longitudinal axis 120 also exists, and two longitudinal strut segments 132 lie in different adjacent radially oriented planes. The transverse strut segments 134 are formed integrally with the longitudinal strut segments 132. The transverse strut segments 134 generally lie in a tangential plane with respect to the radial plane 135 (e.g., the transverse strut segments 134 generally extend within the curved surface of a cylinder or a funnel). As shown in FIG. 1E, in embodiments having an even number of equally spaced longitudinal struts, each radial plane 135 comprises the longitudinal axis 120 of the stent structure 100 and two longitudinal strut segments 132 located on both sides of the stent structure 100.

[0026] The continuous longitudinal strut segments 132 form the longitudinal struts 154. Each longitudinal strut extends along at least a portion of at least one wall (e.g., at least one of the inner wall 104, the outer wall 106, or the transition wall 108). In an embodiment, each longitudinal strut extends along the entirety of the inner wall 104 (e.g., from the first opening 116 to the inner junction 122), the entirety of the transition wall 108 (e.g., from the inner junction 122 to the outer junction 124), and a portion or the entirety of the outer wall 106. In such an embodiment, the longitudinal struts provide structural integrity and better redistribute stress by portions of the inner wall 104, the transition wall 108, and the outer wall 106 that include the longitudinal struts. In some variations, the first region 128 of the outer wall 106 may also include a portion and a termination 156 of the longitudinal strut 154 within the outer wall 106, and the second region 130 of the outer wall 106 may be devoid of any longitudinal struts. On the other hand, a portion of the outer wall 106 that does not include longitudinal struts can exhibit greater flexibility than a portion of the outer wall 106 that includes longitudinal struts. Regardless of the presence or absence of longitudinal struts, a portion of the outer wall may also be characterized as including a longitudinally non-shrinking portion that is continuous with the transition wall and a shrinking portion that is located at the free end of the outer wall. The greater flexibility of a portion of the outer wall 106 that does not include longitudinal struts can facilitate greater expansion of such a portion of the outer wall 106 when switching the stent structure 100 from a folded configuration to an expanded configuration. In a particular embodiment, the length of the longitudinal strut segments of the outer wall may be shorter than, the same as, or longer than the length of the longitudinal strut segments of the inner wall. In other variations, the length of the longitudinal strut segments of the outer wall can be characterized as a percentage of the total longitudinal length of the outer wall, such as 25% - 100%, 30% - 75%, 40% - 60%, etc.

[0027] In certain examples, the first region 128 of the outer wall 106 comprises longitudinal struts, and the second region 130 of the outer wall 106 does not comprise longitudinal struts. The location of the outer wall 106 where the longitudinal struts terminate may be the expected location of the valve annulus (e.g., the tricuspid valve annulus) when the stent structure 100 is placed within the valve. In such examples, the diameter of the second region 130 may be larger than the diameter of the first region 128 when the stent is expanded at the implantation site. The greater flexibility of the portion of the outer wall 106 that does not comprise longitudinal struts may allow that portion of the outer wall 106 that does not comprise longitudinal struts to better conform to adjacent anatomical structures than the portion of the outer wall 106 that comprises longitudinal struts. In embodiments, at least one longitudinal strut may be provided along the entire folded length of the stent structure 100 (e.g., along the length of the inner wall 104, through the transition wall 108, and along the length of the outer wall 106). Further, the shortening of the first region 128 and the second region 130 depends at least in part on the presence of the longitudinal struts 132. For example, the longitudinal struts cause little or no shortening of the first region 128 when switching from the expanded configuration to the folded configuration. The limited shortening of the first region 128 prevents or at least minimizes an increase in the length of the stent structure 100 (measured parallel to the longitudinal axis 120) when switching the stent structure 100 from the expanded configuration to the folded configuration, thereby facilitating insertion of the stent structure 100 into the anatomical structure without interfering with the anatomical structure. The absence of longitudinal strut segments 132 in the second region 130 causes the second region 130 to shorten when switching the stent structure 100 from the expanded configuration to the folded configuration. Note that since the second region 130 can be used to interact with the anatomical structure to fix the stent structure 100, the shortening of the second region 130 is less likely to adversely affect the anatomical structure (e.g., of the tricuspid valve) than the first region 128.

[0028] In an exemplary stent structure 100, the longitudinal strut segments 132 along the lumen 102 of the stent structure 100 have a linear configuration, so the longitudinal strut segments 132 are substantially parallel in both their expanded and contracted configurations. Due to this arrangement, the lumen 102 can exhibit no shortening or limited shortening when changing from the contracted configuration to the expanded configuration. Thereby, the axial elongation of the valve structure attached to the lumen 102 can be reduced or eliminated. This may also enable the lumen 102 to be predictably positioned and deployed while reducing the risk of inadvertent positional shifts.

[0029] The stent structure 100 may comprise any suitable number of longitudinal struts. In one example, the number of longitudinal struts is a multiple of the number of valve leaflets forming the valve. In such an example, the multiple longitudinal struts enable each valve leaflet to be equally supported, thereby preventing or at least suppressing uneven wear between valve leaflets that could cause the valve structure to malfunction. For example, a valve comprising the stent structure 100 may comprise three valve leaflets if the valve is a tricuspid valve. In such a case, the number of longitudinal struts is a multiple of three (e.g., the stent structure 100 comprises 3, 6, 9, 12, 15, 18, or 21 longitudinal struts).

[0030] At least some of the longitudinal strut segments 132 of the inner wall 104 can define one or more perforations 144 that extend therethrough. The perforations 144 are configured to facilitate attachment (e.g., sewing, suturing, stitching, riveting, clipping, stapling) of the valve tip of a valve structure (e.g., the valve tip 668 of the valve structure 664 shown in FIG. 6) to the longitudinal struts. In one example, the longitudinal strut segments 132 that define the perforations 144 may be disposed closer to the first opening 116 of the lumen 102 than the second opening 118. This is because it has generally been found beneficial to dispose the valve tip closer to the first opening 116 than the second opening 118. In one example, the perforations are formed for each second longitudinal stent when the valve has two valve tips, and for each third longitudinal stent when the valve has three valve tips, to prevent or at least mitigate uneven wear between the valve tips. In one example, each longitudinal strut segment 132 that defines the perforations 144 comprises a plurality of perforations 144. In one example, a portion of the longitudinal stent segment 132 that defines the perforations 144 can exhibit a greater width than the remaining portion of the longitudinal stent segment 132, thereby enabling the longitudinal stent segment 132 to accommodate larger perforations 144.

[0031] The transverse struts may form a partial or complete circumferential or outer perimeter around the wall of the stent structure 100. To facilitate expansion and contraction of the entire stent structure 100, one or more transverse strut segments 134, or all transverse strut segments 134, may comprise a pair of inclined legs. Each transverse end of each inclined leg is formed continuously or integrally with a longitudinal strut segment 132, and each inclined leg is joined to each other at the center to form a flexure region. The flexure configuration formed by the two inclined legs can comprise a simple bend, although in other examples, each leg may extend centrally to form a hairpin flexure region.

[0032] The stent structure 100 may comprise any suitable number of transverse stents. In an embodiment, the number of transverse stents may depend on the desired flexibility of the wall comprising the transverse stents and the length of the wall. For example, the first region 128 may comprise fewer transverse stents than adjacent portions of the inner wall 104 because the first region 128 may expand more than the inner wall 104 when expanding from the folded configuration. In an embodiment, the number of transverse stents may depend on the stent configuration of the transverse stents. For example, the stent configuration of the transverse stents in the second region 130 allows for a higher flexibility than the stent configuration of the transverse stents in the first region 128. Thus, the second region 130 may comprise more transverse stents (e.g., 3) than the first region 128 (e.g., 1).

[0033] The transverse strut segments may form different stent configurations (e.g., different stent structures). In FIG. 2A, a part of a stent configuration 200a showing an exemplary configuration of transverse strut segments according to an embodiment is shown. In the illustrated embodiment, the stent configuration 200a comprises a first longitudinal strut segment 232a and a second longitudinal strut segment 232a'. The stent configuration 200a also comprises a first transverse strut segment 234a and a second transverse strut segment 234a'. The first transverse strut segment 234a comprises a first leg 236a extending from the first longitudinal strut segment 232a and a second leg 238a extending from the second longitudinal strut segment 232a'. The first leg 236a and the second leg 238a are joined to each other at the center in a bending region 240a. The second transverse strut segment 234a' comprises a first leg 236a' extending from the first longitudinal strut segment 232a and a second leg 238a' extending from the second longitudinal strut segment 232a'. The first leg 236a' and the second leg 238a' are joined to each other at the center in a bending region 240a'. The longitudinal strut segments 232a, 232a' and the transverse strut segments 234a, 234a' together form a closed outer periphery of the cell 242a.

[0034] In some variations, the legs 236a, 238a, 236a', 238a' can have a substantially straight or straight configuration, and the variations mainly occur at the intersections and bending regions 240a, 240a' between the legs 236a, 238a, 236a', 238a' and the longitudinal strut segments 232a, 232'. In some variations, the legs 236a, 238a, 236a', 238a' may be composed of a substantially straight or straight configuration. In some variations, the legs 236a, 238a, 236a', 238a' can have a substantially curved configuration.

[0035] The first lateral strut segment 234a and the second lateral strut segment 234a' can have an acute leg angle θ measured between the straight or substantially straight portions of the legs 236a, 238a, 236a', 238a' and the longitudinal strut segments adjacent thereto. For example, the acute leg angle θ may be measured between the straight or substantially straight portion of the first leg 236a of the first lateral strut segment 234a and the first longitudinal strut segment 232a. The acute leg angle θ can vary, for example, depending on whether the strut configuration 200a forms part of the inner wall or the outer wall, since the outer wall exhibits more shortening than the inner wall. Generally, the acute leg angle θ is smaller when the stent configuration 200a forms part of the inner wall than when the stent configuration 200a forms part of the outer wall. For example, when the stent configuration 200a forms part of the inner wall, the acute leg angle θ may be 50° or less, 45° or less, 40° or less, 35° or less, 30° or less, 25° or less, 20° or less, 15° or less, or in the range of 10° - 20°, 15° - 25°, 20° - 30°, 25° - 35°, 30° - 40°, 35° - 45°, or 40° - 50°. When the stent configuration 200a forms part of the outer wall, the acute leg angle θ may be 30° or more, 35° or more, 40° or more, 45° or more, 50° or more, 55° or more, 60° or more, 65° or more, 70° or more, or in the range of 30° - 40°, 35° - 45°, 40° - 50°, 45° - 55°, 50° - 60°, 55° - 65°, or 60° - 70°.

[0036] The first and second lateral strut segments 234a may be separated from each other by a maximum distance d measured parallel to the longitudinal axis of the lumen (not shown in FIG. 2A). The maximum distance d can be selected to be 3 mm to 5 mm, 4 mm to 6 mm, 5 mm to 7 mm, 6 mm to 8 mm, 7 mm to 9 mm, 8 mm to 10 mm, 9 mm to 11 mm, or 10 mm to 12 mm. In embodiments, the maximum distance d may vary depending on whether the strut configuration 200a forms part of the inner wall or the outer wall, as it can affect the flexibility of the wall. Generally, the maximum distance d may be smaller when the strut configuration 200a forms part of the inner wall than when the strut configuration 200a forms part of the outer wall, as the inner wall may exhibit a smaller shortening than the outer wall.

[0037] In the schematic strut configuration 200a shown in FIG. 2A, the longitudinal strut segments 232a, 232a' may be parallel or non-parallel depending on whether the wall comprising the longitudinal strut segments 232a, 232a' is cylindrical or non-cylindrical (e.g., frustoconical). In a variant, when the longitudinal strut segments 232a, 232a' are non-parallel, the longitudinal struts 232a, 232a' can have a small radial angle orientation of 1° to 5°, 2° to 10°, or 5° to 30° from the longitudinal axis.

[0038] In some variants, when greater rigidity is desired, the lateral strut segments 234a, 234a' may be substantially non-uniform along their length. This can be achieved by increasing the relative width of the lateral strut segments 234a, 234a' near the intersection with the longitudinal strut segments adjacent to the legs 236a, 238a, 236a', 238a' and decreasing the relative width of the lateral strut segments 234a, 234a' in or near the bending regions 240a, 240a'.

[0039] In some variations, the bending regions 240a, 240a' can have a simple angle or a curved configuration. In other variations, the bending regions 240a, 240a' can have an arcuate structure having a greater curvature on the same side as the acute angle of the lateral strut segment and a smaller curvature on the obtuse angle side of the lateral strut segment.

[0040] In some embodiments, the orientation of the lateral strut segments 234a, 234a' may vary. In one example, as shown in FIG. 2A, the lateral strut segments 234a, 234a' may be oriented such that the lateral strut segments 234a, 234a' are substantially parallel. In such an example, the flexion regions 240a, 240a' may be oriented in the same direction (e.g., point), and the cell 242a may exhibit a chevron shape. The flexion regions 240a, 240a' may be oriented in the upstream or downstream direction. By orienting the lateral strut segments 134a, 234a' parallel to each other, it is possible to prevent the lateral strut segments 234a, 234a' from contacting each other when the stent configuration 200a is in the folded configuration, because such contact may limit the degree to which the stent configuration 200a can be contracted. In one example, the lateral strut segments 234a, 234a' may be oriented such that the lateral strut segments 234a, 234a' are not parallel. In such an example, the flexion regions 240a, 240a' may be oriented in different directions (e.g., point), and the cell 242a may exhibit an hourglass or diamond shape. In one example, the lateral strut segments 234a, 234a' may be oriented such that the flexion regions 240a, 240a' are directed away from the respective wall terminations closest to the lateral strut segments 234a, 234a'. For example, the flexion regions 240a, 240a' may be directed away from the first or second opening of the lumen (e.g., the first or second opening 116, 118) when the strut configuration 200a forms part of the inner wall, or away from the outer junction or outer opening when the stent configuration 200a forms part of the outer wall. By directing the flexion regions 240a, 240a' away from their respective wall terminations, it is possible to prevent the flexion regions 240a, 240a' from protruding from the remainder of the stent structure when the flexion regions 240a, 240a' are in the folded configuration. It should be noted that in some embodiments, as shown in FIG. 1D, the lateral stent segments may be sufficiently offset from the wall terminations such that the lateral stent segments are less likely to protrude from the remainder of the stent.

[0041] FIG. 2B shows another exemplary embodiment of the stent configuration 200b. Unless otherwise disclosed herein, the stent configuration 200b is the same as or substantially similar to the stent configuration 200a. For example, the stent configuration 200b includes a first lateral strut segment 234b and a second lateral strut segment 234b'. The first lateral strut segment 234b includes a first leg 236b and a second leg 238b joined to each other at the center in the bending region 240b. The second lateral strut segment 234b' includes a first leg 236b' and a second leg 238b' joined to each other at the center in the bending region 240b'. The lateral strut segments 234a, 234b' together form a closed outer periphery of the stent opening or cell 242b. The stent configuration 200b may or may not include a longitudinal strut segment (as shown in the figure).

[0042] The legs 236b, 238b', 236b', 238b' of the lateral strut segments 234b, 234b' can have a curved or curvilinear configuration in their expanded configuration. For example, each leg 236, 238 may exhibit a substantially S-shaped configuration. The substantially S-shaped configuration of the legs 236b, 238b', 236b', 238b' can allow for a greater expansion amount of the strut configuration 200b from the folded configuration to the expanded configuration, and / or can distribute more stress and strain along the entire length of the strut configuration 200b.

[0043] A further example of a strut configuration is disclosed in U.S. Patent No. 11,197,755, issued on December 14, 2021, the disclosure of which is hereby incorporated by reference in its entirety.

[0044] Referring back to FIGS. 1A - 1E, whether the lateral strut segment 134 exhibits the strut configuration 200a of FIG. 2A, the strut configuration 200b of FIG. 2B, or any other strut configuration may depend on where the lateral strut segment 134 is disposed on the strut structure 100. For example, the lateral strut segment 134 of the inner wall 104 can generally exhibit the strut configuration 200a of FIG. 2A because the amount of radial expansion indicated by the inner wall 104 is relatively small. In other words, the lateral strut segment 134 of the inner wall 104 can exhibit a substantially linear configuration where deformation occurs mainly at the intersection and its bending region between the lateral strut segment 134 and the adjacent longitudinal strut segment 132. The bending region of the lateral strut segment 134 may be oriented away from the nearest end of the inner wall 104. Thus, the lateral strut segment 134 can form cells that exhibit a chevron, hourglass, or other suitable shape. The lateral strut segment 134 of the first region 128 can also generally exhibit the strut configuration 200a of FIG. 2A because the amount of radial expansion indicated by the first region 128 is relatively small compared to the second region 130. The lateral strut segment 134 of the second region 130 can generally exhibit the strut configuration 200b of FIG. 2B that allows the lateral strut segments 134 to remain interconnected even if the second region 130 does not include longitudinal struts. The lateral strut segment 134 of the second region 130 also allows the second region 130 to exhibit greater flexibility than the inner wall 104 of the outer wall 106 and the first region 128. The greater flexibility of the second region 130 facilitates switching of the stent structure 100 from its folded configuration to its expanded configuration. The greater flexibility of the second region 130 also facilitates the second region 130 conforming to the surrounding anatomical structure.

[0045] In an embodiment, the leg length of the lateral strut segment 134 of the inner wall 104 is typically shorter than the leg length of the lateral strut segment 134 of the outer wall 106 because the amount of radial expansion indicated by the inner wall 104 is relatively small compared to the outer wall 106.

[0046] The spacing between adjacent longitudinal or transverse struts may be equal throughout the stent structure 100 or may vary along the folded stent structure. In the case of longitudinal struts, the number of struts can vary according to the desired flexibility or radial expansion force desired for the stent structure 100, or based on the desired strut segment width to achieve the desired radial expansion force or flexibility. In the case of transverse struts, relatively large spacings can be provided in regions where greater radial expansion and / or reduced expansion force is desired, and small spacings are desirable in regions where radial expansion is reduced and / or the expansion force is greater.

[0047] The stent structure 100 may include one or more returns 146 that deviate radially outward with respect to adjacent struts. The returns 146 are configured to penetrate or otherwise push into adjacent anatomical structures. Penetrating or otherwise pushing the returns 146 into the anatomical structure can help fix the stent structure 100 to the anatomical structure. For example, as described above, the enlarged diameter region of the outer wall 106 provides mechanical interference or resistance to displacement. However, the enlarged diameter region of the outer wall 106 may only provide mechanical interference to the resistant displacement of the stent structure 100 in the downstream direction. Thus, the enlarged diameter region of the outer wall 106 can prevent displacement of the stent structure 100 when the upstream pressure of the stent structure 100 increases (e.g., when the atrial chamber receives blood from the superior vena cava). However, the enlarged diameter region of the outer wall 106 may not prevent or inhibit its displacement when the downstream pressure increases (e.g., when the ventricular chamber pumps blood through the pulmonary valve). Pushing the returns 146 into the anatomical structure can provide mechanical interference or resistance to the displacement of the stent structure 100 caused by an increase in downstream pressure of the stent structure 100.

[0048] The returns 146 can be disposed anywhere along and / or around the outer wall 106 of the stent structure 100. In embodiments, at least some of the returns 146 may be disposed in the second region 130 of the outer wall 106 because the second region 130 may contact the anatomical structure due to its relatively flexibility. In such embodiments, since such portions of the transverse stent segments 134 may exhibit greater rigidity and strength than other portions of the transverse stent segments 134, the returns 146 can extend outwardly from portions of the transverse stent segments 134 that cross each other. Alternatively or additionally, the returns 146 may extend from portions of the transverse stent segments 134 that do not cross other transverse stent segments 134, such as in the bending regions of the transverse stent segments 134. It should be noted that the shortening of the second region 130 increases the number of returns 146 that can be formed thereon. In embodiments, at least some of the returns 146 extend outwardly from the first region 128. The returns 146 can have a length 158 in the range of, for example, 1 mm to 10 mm, 2 mm to 8 mm, 3 mm to 6 mm, or 3 mm to 5 mm.

[0049] In embodiments, the returns 146 may be oriented towards the outer opening 126 rather than the outer junction 124. Such an orientation of the returns 146 can facilitate pushing the returns 146 into the anatomical structure when the pressure downstream of the stent structure 100 increases. In embodiments, the returns 146 can extend outwardly from the outer wall 106 by 2 to 10 mm, 3 to 9 mm, or 4 to 6 mm. In embodiments, the number of returns 146 formed on the stent structure 100 may be 1 to 10, 5 to 15, 10 to 20, 15 to 25, 20 to 30, 25 to 35, 30 to 40, 35 to 45, 40 to 50, 45 to 55, or 50 to 60. In general, it should be noted that by increasing the number of returns 146, the returns 146 can more securely fix the stent structure 100 to the anatomical structure. The returns can have a substantially linear or arcuate shape.

[0050] When in the expanded configuration, the stent structure 100 may have one or more of the following characteristics. 1) A net longitudinal stent length in the range of 15 - 55 mm, 20 - 50 mm, or 30 - 40 mm (i.e., the maximum distance the stent extends along the longitudinal axis 120); 2) A maximum stent diameter or transverse dimension in the range of 40 - 80 mm, 50 - 70 mm, or 55 - 65 mm; 3) A maximum stent diameter or transverse dimension measured at the outer junction 124 within the range of 15 - 60, 20 - 50 mm, or 25 - 40 mm, optionally, a maximum stent diameter or transverse dimension that is 10 - 40 mm, 15 - 35 mm, or 20 - 30 mm smaller than the maximum stent diameter or transverse dimension; 4) A lumen length in the range of 10 - 50 mm, 15 - 40 mm, or 20 - 30 mm; 5) A lumen diameter or maximum cross-sectional dimension in the range of 10 - 40 mm, 15 - 35 mm, or 26 - 31 mm; 6) A transition wall radial width measured between the inner junction 122 and the outer junction 124 in the range of 2 - 10 mm, 3 - 9 mm, 4 - 8 mm, or 5 - 7 mm; 7) An outer wall longitudinal length in the range of 10 - 40 mm, 20 - 35 mm, or 25 - 30 mm, measured parallel to the longitudinal axis 120 and from the outer junction 124 to the outer opening 126; 8) A ratio of the outer wall longitudinal length to the maximum stent diameter (i.e., outer wall longitudinal length / maximum stent diameter) in the range of 0.35 or 1.0, 0.45 - 0.80, or 0.50 - 0.60; 9) Some longitudinal struts selected from the group consisting of one or more of, for example, 3, 6, 9, 12, 15, 18, or 21 longitudinal struts that are divisible by 3; 10) A ratio between the radial distance between the return tip and the longitudinal axis of the stent structure and the radial distance between an adjacent longitudinal strut or outer wall segment (excluding the return) and the longitudinal axis of the stent structure, the ratio being in the range of 1.1 - 1.5, 1.05 - 1.30, 1.05 - 1.20, or 1.05 - 1.15; and / or 11) An offset between the second inner opening 118 and the outer opening 126, being positive (i.e., protruding from the outer opening), neutral (i.e., flush with the outer opening), negative (i.e., recessed from the outer opening), and / or in the range of -4 to -12 mm, -5 to -10 mm, -6 to -9 mm, +1 to +8 mm, +2 to +6 mm, +3 to +5 mm, -3 to +3 mm, +0 to +3 mm, -12 to +5 mm, -6 to +6 mm, or -7 mm to +4 mm.

[0051] The stent structure 100 need not be limited to require a selection of each of the characteristics listed above, and a single characteristic or a subset of characteristics is also contemplated.

[0052] In the embodiments shown in FIGS. 1A - 1E, the stent structure 100 comprises a plurality of longitudinal struts and a plurality of transverse struts, each comprising a continuous set of consecutive longitudinal or transverse strut segments. In a particular example of the stent structure 100, nine equally spaced longitudinal struts are provided and seven sets of complete transverse struts are provided along the folded stent structure 100. Three sets of closely spaced transverse struts are provided along the inner wall 104, having relatively straight or minimally curved legs, with their bending regions oriented away from the closest end of the inner wall 104. The transition wall 108 does not comprise transverse struts having a relatively uniform radius of curvature. The outer wall 106 comprises four sets of transverse struts.

[0053] The replacement valve may further comprise one or more skirt materials for one or more regions of the stent structure. The skirt material may comprise a solid, dense weave or loose knit fabric sheet of self, same, or different or artificial materials, which may be the same as or different from the valve tip material of the valve. The skirt material may comprise a polytetrafluoroethylene (PTFE), polyester or polyethylene terephthalate (PET) material. In a variant comprising an open pore material, the average pore size may be in the size range of about 0.035 mm to 0.16 mm, or 0.05 mm to 0.10 mm, or 0.07 mm to 0.09 mm. The open pore material may provide greater elasticity or flexibility in regions of the stent structure that are subject to greater configurational changes. In other regions of the stent, a solid sheet material lacking pores, which does not require elasticity or flexibility, may be provided. The skirt material can comprise a single-layer or multi-layer structure and can comprise one or more coatings for regulating thrombosis, in-growth, and / or lubricity.

[0054] As described above, the stent structure disclosed herein may include one or more returns. In an embodiment, the skirt material does not initially define one or more holes corresponding to the one or more returns of the stent structure. In such an embodiment, the return can pierce the skirt material to form a slit in the skirt material through which the return can extend. The slit in the skirt material formed by the return can have sharp or other jagged features that form stress concentration regions that weaken the skirt material. In an embodiment, the skirt material initially defines one or more holes corresponding to the one or more returns of the stent structure. The holes allow the return to extend through the skirt material without tearing the skirt material. Unlike a slit, the holes may not substantially include sharp or jagged features that can form stress concentration regions, thereby significantly reducing the likelihood that the skirt material will fail during use. In an embodiment, the skirt material does not initially define one or more holes corresponding to the one or more returns of the stent structure. In such an embodiment, as described above, the return can form a slit in the skirt material. After forming the slit, the portion of the skirt material defining the slit can be heated (e.g., melted) to reduce the number of stress concentration regions formed by the slit.

[0055] FIG. 3 is a schematic cross-sectional view of a replacement valve 350 comprising a stent structure 300 and a skirt material 352, according to an embodiment. Unless otherwise disclosed herein, the replacement valve 350 is the same as or substantially similar to any of the replacement valves disclosed herein. The skirt material 352 comprises two different materials, a woven material 354 and a knit material 356, attached to the stent structure 300. The woven material 354 comprises a solid or dense woven material. The woven material 354 is disposed on at least a portion (e.g., all or most) of the inner wall 304 defining the lumen 302 and at least a portion of the second end 330 of the outer wall 306. The woven material 354 may also extend across the outer opening 326. The woven material 354 may be substantially more impermeable than the knit material 356, or at least more impermeable to blood. In other words, the woven material 354 forms a barrier to blood flow. The woven material 354 extending across the outer opening 326 can direct blood from an upstream location through the first opening 316 of the lumen 302 into the lumen 302. For example, the woven material 354 extending across the outer opening 326 can be inclined with respect to the longitudinal axis 320 to form a funnel that directs blood into the lumen 302. The woven material 354 disposed in the lumen 302 prevents or at least inhibits blood from flowing out of the lumen 302, except through the second opening 318 of the lumen 302. The woven material 354 disposed across the outer opening 326 and disposed on the second region 330 of the outer wall 306 substantially prevents backflow of blood from a downstream location of the replacement valve 350 to an upstream location of the replacement valve 350 because the second region 330 generally abuts an anatomical structure of an individual. Thus, the woven material 354 can direct the flow of blood through the replacement valve 350 and prevent backflow of blood through the replacement valve 350.

[0056] The knit material 356 may be disposed in the remaining portion of the stent structure 300 that is not covered by the woven material 354. For example, the knit material 356 may be disposed in at least a portion of the transition wall 308 and the first region 328 of the outer wall 306. Optionally, the knit material 356 may also be disposed adjacent to portions of the inner wall 304 and the second region 330 that are not covered by the woven material 354, such as a portion of the inner wall 304 downstream of a valve structure (not shown). The knit material 356 exhibits greater blood permeability than the woven material 354. The increased blood permeability of the knit material 356 results in cell migration and tissue ingrowth into the replacement valve 350. The increased blood permeability of the knit material 356 also enables blood to flow within the annular cavity 310, thereby suppressing or at least reducing the pressure differential between the annular cavity 310, which may fold the stent structure 300, and the location downstream of the replacement valve 350. It should be noted that the knit material 356 can exhibit a porosity small enough to resist the passage of thrombi that may form within the annular cavity 310.

[0057] The knitted material 356 can exhibit greater flexibility than the woven material 354. Thus, including the knitted material 356 in the skirt material 352 makes it easier to expand the stent structure 300 from the folded configuration than if the skirt material 352 comprised only the woven material 354. However, the woven material 354 is disposed in the portion of the stent structure 300 that expands the most when the stent structure 300 expands from its contracted configuration (e.g., the second region 330). In an embodiment, the portion of the woven material 354 disposed on the second region 330 may define one or more slits 358 (schematically shown in FIG. 3 using small gaps). The slits 358 may extend at least partially across the cells formed in the stent structure 300. The slits 358 extending across different cells may be continuous (i.e., a single slit 358 extends across multiple cells) or discontinuous (i.e., each slit 358 extends only across a single cell). The slits 358 enable the stent structure 300 to contract and expand freely. For example, the cells of the stent structure 300 can elongate in the vertical direction when the stent structure 300 is in the folded configuration. The slits 358 prevent the relatively rigid woven material 354 from restricting such elongation of the cells because the slits 358 separate the woven material 354. The slits 358 may be configured to overlap or otherwise substantially close when the stent structure 300 is expanded, thereby preventing blood from flowing through the slits 358.

[0058] FIG. 4 is a schematic cross-sectional view of a replacement valve 450 comprising a stent structure 400 and a skirt material 452, according to an embodiment. Unless otherwise disclosed herein, the replacement valve 450 is the same as or substantially similar to any of the replacement valves disclosed herein. For example, the skirt material 452 can comprise a woven material 454 and a knitted material 456.

[0059] The woven material 454 may be disposed on at least a portion of the inner wall 404 that defines the inner lumen 402 and at least a portion of the second region 430 of the outer wall 406. The woven material 454 does not extend across the outer opening 426. Instead, the woven material 454 extends between a portion of the inner wall 404 and a portion of the second region 430 at an intermediate position spaced from the second opening 418 and the outer opening 426. The woven material 454 extending across the intermediate position allows blood to flow from a position upstream of the replacement valve 450 to a portion of the annular cavity 410, thereby minimizing the pressure differential between the upstream position and the annular cavity 410, which could otherwise tear the woven material 454. Note that the woven material 454 extending across the intermediate position can abut a portion of the second region 430 having the woven material 454 disposed thereon on the opposite side to prevent backflow of blood. In an embodiment, a portion of the woven material 454 extending across the intermediate position can be inclined with respect to the longitudinal axis 420 to form a funnel that directs blood into the inner lumen 402. In such an embodiment, a portion of the woven material 454 disposed in the inner lumen 402 adjacent to a portion of the woven material 454 extending across the intermediate position can define one or more holes 460, thereby allowing blood to flow from the annular cavity 410 into the inner lumen 402. The knit material 456 may be disposed on portions of the stent structure 400 not covered by the woven material 454.

[0060] Figure 5 is an isometric view of a replacement valve 550 according to an embodiment. Unless otherwise disclosed herein, the replacement valve 550 is the same as or substantially similar to any of the replacement valves 550 disclosed herein. For example, the replacement valve 550 can include a stent structure (not shown, unclear) and a skirt material 552.

[0061] The skirt material 552 can define one or more lead openings 562 configured to allow a conductive wire (e.g., a wire) to extend through the replacement valve 550. For example, depending on the position of the replacement valve 550, the replacement valve 550 may be disposed in a passage through which a conductive wire from a pacemaker or other conductive wire extends into the heart. The lead openings 562 formed in the skirt material 552 allow these conductive wires to pass through the replacement valve 550, thereby preventing the replacement valve 550 from obstructing the passage of such conductive wires.

[0062] The lead openings 562 can comprise any suitable opening. In embodiments, the lead openings 562 can comprise a hinged door, a trap door, a permeable and / or pierceable membrane, or a duckbill port, because these structures can prevent or at least impede blood backflow through the lead openings 562. In embodiments, the lead openings 562 may be formed in a portion of the skirt material 552 and extend across an outer opening (as shown), be disposed on an inner wall of the stent structure, be disposed on a transition wall of the stent structure, be disposed on an outer wall of the stent structure (e.g., a first or second region), or extend across an intermediate position spaced from the outer opening, with at least one of these being done.

[0063] As described above, the replacement valves disclosed herein may comprise a valve structure. FIG. 6 is an isometric view of a replacement valve 650 comprising a valve structure 664 according to an embodiment. Unless otherwise disclosed herein, the replacement valve 650 is the same as or substantially similar to any of the replacement valves disclosed herein. For example, the replacement valve 650 comprises a stent structure (not shown, unclear) and a skirt material 652.

[0064] The replacement valve 650 may be configured such that blood flow can enter through the second opening 618, flow through the lumen 602, and exit through a first opening (not shown, unclear). Thus, the replacement valve 650 can include a valve structure 664 attached to the lumen 602. The valve structure 664 can be any of a variety of valve structures including a flap valve, a ball-in-cage valve, or a cusp valve. When a cusp valve is provided, the valve structure 664 includes a plurality of cusps 668. The cusps 668 can be made of autologous, allogeneic, or xenogeneic or artificial materials, such as natural materials or anatomical structures like porcine, bovine, or equine pericardial tissue or valves, or biomaterials derived from the patient's own cells, and can be fixed with any of a variety of chemicals such as glutaraldehyde to reduce the antigenicity of the valve and / or to modify the physiological and / or mechanical properties of the valve material. The cusp valve can be a two-cusp or three-cusp valve structure. As described above, the cusp valve 668 can be attached or sutured to the longitudinal and / or transverse struts of the lumen 602 using perforations.

[0065] Manufacturing In some variations, the stent structure may be manufactured using a superelastic nitinol tube that is laser cut with various slits and slots to achieve an initial tubular stent shape. Next, in a series of periodic deformation, heating, and cooling steps, the tubular stent is gradually expanded at least to the initial size of the lumen of the stent structure. Then, a portion of the stent structure corresponding to the transition wall and the outer wall is further gradually expanded to the desired diameter, and then a stepwise eversion to form the outer wall is performed using a mandrel to achieve the shape of the outer wall. In another step, one or more bending regions of the transverse struts around the intermediate region are displaced radially outward to form the returns.

[0066] In an alternative embodiment, after initially cutting the tube, the tube may be subjected to a series of periodic deformation, heating, and cooling steps to expand the tube stepwise to at least the initial size of the outer lumen of the stent structure, after which a portion of the stent structure corresponding to the transition wall and the inner wall is inverted into the outer wall to form the closed end and the inner wall. The outer wall can be further expanded or stepwise adjusted to a desired shape, for example, by further expanding the open end region and the closed end region of the outer wall, or by reducing the cross-sectional size or diameter of the intermediate region. One or more buckling regions on the lateral struts around the intermediate region may also be displaced radially outward to form a retention loop or structure.

[0067] Valve Loading and Delivery In embodiments, one or more sutures (e.g., tension members) can be attached to a replacement valve (e.g., relative to the stent structure of the replacement valve) to control the expansion and contraction of different regions on the stent structure until final deployment at the treatment site. In other embodiments, the suture or wrap may be provided across one or more regions of the stent structure.

[0068] In some examples, the suture may be tensioned or clamped to fold the outer wall and the inner wall of the stent structure for loading onto a delivery catheter. The suture may be manipulated to first fold the inner wall before the outer wall, or both may be folded simultaneously. Similarly, one end of the inner wall or the outer wall may be folded first, or both ends of the inner wall or the outer wall may be folded simultaneously. This can be done at room temperature, or in a cold sterile water or ice water bath during use or manufacturing. After folding, the sheath may extend distally beyond the distal catheter portion where the replacement valve is present. The valve can also be rinsed with sterile saline prior to loading to remove preservatives remaining on the valve.

[0069] In some variations, the transition wall of the stent structure is folded at the inner junction, such that in the folded configuration, the transition wall is positioned directly above the delivery catheter or tool like an inner wall. In other examples, the outer wall is pulled distally during folding and loading, and the transition wall is expanded at the outer junction such that when the transition wall is contracted into the folded configuration, it is positioned radially outward from the inner wall.

[0070] The retention suture of the delivery system can be proximally controlled by the user using a pull ring, a sliding lever, and / or a rotating knob, which are further configured to lock in place except during movement via a biasing spring or a mechanical mating lock configuration, as is known in the art. The proximal end of the delivery system may also be robotically controlled using any of a variety of robotic catheter guidance systems known in the art. The suture can slide along one or more lumens of the delivery catheter in addition to any provided flush lumen, guidewire lumen, or steering wire lumen with a rapid exchange guidewire configuration. The suture can exit at different positions around the distal region of the delivery catheter and can exit around the distal region of the catheter through multiple openings. The multiple openings may be spaced apart around the circumference of the catheter body and / or longitudinally spaced apart depending on the region of the stent structure controlled by the suture.

[0071] In one exemplary method of delivering a replacement valve, the patient is positioned on the treatment table and draped and sterilized in the usual manner. Anesthesia or sedation is achieved. Percutaneous or surgical access to the femoral vein is obtained and an introducer guidewire is inserted. The guidewire is manipulated to reach the right atrium. Alternatively, image guidance may be used to detect whether a patent foramen ovale or other access is available, and the guidewire may pass through an existing anatomical opening. An electrocautery catheter can also be used to create an opening in the atrial septum. Once in the right atrium, the guidewire passes through the tricuspid valve.

[0072] Referring to FIG. 7A, a delivery system 770 having a delivery catheter 772 and a valve 750 is positioned across the tricuspid valve opening 776. For clarity, only the stent structure of the valve 750 is shown in FIG. 7A. The delivery system 770 may also be further manipulated to adjust the entry angle through the tricuspid valve opening 776 to be substantially orthogonal to the native valve opening and / or to be positioned at the center of the tricuspid valve opening 776. Once the desired catheter position is achieved, the delivery catheter 772 is retracted proximally to expose the folded valve 750.

[0073] In an embodiment, a set of sutures (not shown) is removed, thereby enabling the folded valve 750 to expand. All of the set of sutures may be removed simultaneously, or in a set order, or may be partially released. In some variations, if the valve 750 is mispositioned, the sutures can be re-tensioned to refold the valve 750 and facilitate repositioning and / or reorientation of the valve 750. After the valve 750 is correctly positioned and expanded, the sutures can be cut, otherwise released, or separated from the valve, and the sutures may be withdrawn into the catheter and optionally out of the proximal end of the catheter. The delivery catheter and guidewire can then be withdrawn from the patient, and hemostasis is achieved at the femoral vein site.

[0074] Expanding the valve 750 can comprise at least partially expanding the transition wall 708 and outer wall 706 of the valve 750 outwardly. The expansion of the transition wall 708 and outer wall 706 helps, for example, to further center and orient the valve 750 before complete release. The expansion of the outer wall 706 can also expose the returns extending from the outer wall 706 to contact the anatomical structure of the tricuspid valve 776. Expanding the valve 750 can also comprise expanding the inner wall 704, which also enables the outer wall 706 to achieve its non-contiguous expansion relative to the tricuspid valve opening 776. FIG. 7B shows the valve 750 fully expanded and correctly positioned within the tricuspid valve opening 776.

[0075] Embodiments of this specification are particularly shown and described with reference to those embodiments, but those skilled in the art will understand that various changes in form and detail can be made without departing from the scope of the embodiments. For all of the above embodiments, the steps of the method need not be executed continuously.

Claims

1. A replacement heart valve, which is a single-piece stent structure, having a folded configuration and an expanded configuration, an outer wall including an enlarged diameter region and a reduced diameter region, an inner wall defining a lumen, a transition wall between the outer wall and the inner wall, and a valve structure disposed in the lumen of the inner wall, including a single-piece stent structure, wherein the single-piece stent structure further includes a plurality of longitudinally extending struts and a plurality of laterally extending struts integrally formed, and each longitudinally extending strut is continuously disposed along a part of the inner wall, the transition wall, and the outer wall, wherein a ratio of an axial length of a part of the outer wall having none of the plurality of longitudinally extending struts to an axial length of a part of the outer wall having at least a part of the plurality of longitudinally extending struts is in a range of 1:1 to 1:1.

5. A replacement heart valve.

2. The replacement heart valve according to claim 1, wherein the replacement heart valve is a tricuspid replacement valve.

3. The replacement heart valve according to claim 1, wherein the transition wall is downstream of the enlarged diameter region.

4. The outer wall includes a first region extending from the transition wall and a second region extending from an open end of the outer wall, the first region including the plurality of longitudinally extending struts, and the second region not including the plurality of longitudinally extending struts. The replacement heart valve according to claim 1.

5. The first region includes at least one of the plurality of laterally extending struts, the second region includes at least one of the plurality of laterally extending struts, and at least one of the plurality of laterally extending struts in the first region exhibits a strut configuration different from that of at least one of the plurality of laterally extending struts in the second region. The replacement heart valve according to claim 4.

6. At least one of the plurality of laterally extending struts in the first region includes a substantially straight leg with deformation near the end of each leg, and at least one of the plurality of laterally extending struts in the second region includes a leg exhibiting a substantially S shape. The replacement heart valve according to claim 5.

7. At least a part of the first region of the outer wall is configured to be disposed in a ventricle of the heart, and at least a part of the second region of the outer wall is configured to be disposed in an atrium of the heart. The replacement heart valve according to claim 4.

8. The second region of the outer wall is configured to be more flexible than the first region of the outer wall. The replacement heart valve according to claim 4.

9. The outer wall includes a plurality of returns extending therefrom, the prosthetic heart valve according to claim 1.

10. The outer wall includes a first region extending from the transition wall and a second region extending from the open end of the outer wall, the first region including the plurality of longitudinal struts, the second region not including the plurality of longitudinal struts, The plurality of returns extend from the second region of the outer wall, the prosthetic heart valve according to claim 9.

11. The plurality of returns are oriented toward the outer opening of the outer wall relative to the transition wall, the prosthetic heart valve according to claim 9.

12. The plurality of longitudinal struts and the plurality of transverse struts include nitinol, the prosthetic heart valve according to claim 1.

13. The prosthetic heart valve according to claim 1 further includes skirt material disposed on at least a portion of the outer wall, at least a portion of the inner wall, and at least a portion of the transition wall.

14. The skirt material includes a first material and a second material different from the first material, the prosthetic heart valve according to claim 13.

15. The first material includes a woven material, and the second material includes a knit material, the prosthetic heart valve according to claim 14.

16. The woven material is disposed on at least a portion of the inner wall and at least a portion of the outer wall extending from the outer opening of the outer wall, a portion of the woven material extending between the inner wall and the outer wall, the knit material being disposed on at least a portion of the transition wall and a portion of the outer wall extending from the transition wall, the prosthetic heart valve according to claim 15.

17. The portion of the woven material extending between the inner wall and the outer wall extends across the outer opening, the prosthetic heart valve according to claim 16.

18. The portion of the woven material extending between the inner wall and the outer wall extends across an intermediate position spaced from the outer opening, the prosthetic heart valve according to claim 16.

19. The outer wall includes a plurality of returns extending therefrom, The skirt material includes a plurality of openings formed therein, each of the plurality of openings configured to receive one of the plurality of returns, the prosthetic heart valve according to claim 13.

20. The skirt material defines one or more lead openings configured to allow one or more electrical conductors to pass therethrough, the prosthetic heart valve according to claim 13.

21. The ratio of the axial length of the part of the outer wall that does not have any of the plurality of vertical struts to the axial length of the part of the outer wall that has at least a part of the plurality of vertical struts is within the range of 1:1.0 to 1:1.

4. The replacement heart valve according to any one of claims 1 to 20.

22. The inflow angle between the inlet of the outer wall and the inlet of the inner wall is within the range of 5 degrees to 35 degrees. The replacement heart valve according to any one of claims 1 to 21.

23. The inflow angle is within the range of 25 degrees to 35 degrees. The replacement heart valve according to claim 22.

24. The ratio of the diameter of the inner wall to the diameter of the outer wall at the end point of at least one of the plurality of vertical struts is within the range of 1:1 to 1:

2. The replacement heart valve according to any one of claims 1 to 23.

25. The ratio between the diameter of the inner wall and the diameter of the outer wall at the end point of at least one of the plurality of vertical struts is within the range of 1.4 to 1.

6. The replacement heart valve according to claim 24.

26. The transition wall has an average radius of curvature in the range of about 1 mm to 5 mm. The replacement heart valve according to any one of claims 1 to 25.

27. The average radius of curvature of the transition wall is within the range of about 1.5 mm to 3 mm. The replacement heart valve according to claim 26.

28. The ratio of the axial dimension of the combined inner wall and transition wall to the axial dimension of the combined outer wall and transition wall is within the range of about 1:1 to 1:1.

5. The replacement heart valve according to any one of claims 1 to 27.

29. The ratio of the axial dimension of the combined inner wall and transition wall to the axial dimension of the combined outer wall and transition wall is within the range of about 1.1 to 1.

3. The replacement heart valve according to claim 28.

30. The ratio of the axial dimension of the inner wall to the axial dimension of the outer wall is within the range of about 1:05 to 1:1.

4. The replacement heart valve according to any one of claims 1 to 29.

31. The ratio of the axial dimension of the inner wall to the axial dimension of the outer wall is within the range of about 1.1 to 1.

3. The replacement heart valve according to claim 30.

32. The ratio of the diameter of the outer wall including at least one end of the plurality of vertical struts to the maximum diameter of the outer wall is within the range of 1:1 to 1:1.

5. The replacement heart valve according to any one of claims 1 to 31.

33. The ratio of the diameter of the outer wall including at least one end of the plurality of vertical struts to the maximum diameter of the outer wall is in the range of 1:1.2 to 1:1.4, the prosthetic heart valve according to claim 32.

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