Occluder with stretchable waist

Abstract

To dispose an occluder for a structural heart defect.SOLUTION: An occluder 1 comprises a tubular interlaced structure having a pitch that varies along an axial length of the occluder; a proximal element 4; a distal element 6; and an intermediate element 8 extending between the proximal element and the distal element. According to one aspect, at least one transition section 9b of the pitch, from a first pitch to a second pitch, is located closer to the intermediate element of the occluder than an outer circumference of at least one of the proximal element and the distal element when the occluder is in a relaxed state. According to another aspect, the occluder is extendible from the relaxed state to an axially extended state, where a load to extension ratio, measured in N / mm, provided by the occluder is less than about 0.75 when extended at least 2 mm.SELECTED DRAWING: Figure 2b

Description

[Technical Field]

[0001] The present invention relates to the field of endovascular and / or cardiac occluders and devices such as atrial septal defect (ASD) occluders, patent foramen ovale (PFO) occluders, PDA (patent ductus arteriosus) occluders, PLD (paravalvular leak devices), TAVI (transcatheter aortic valve implantation) PLD, VSD (ventricular septal defect) occluders, LAA (left atrial appendage) occluders, AFR (atrial flow regulators), fistula devices, and / or reciprocal atrial flow diverters such as VP (vascular plug) devices. In particular, these devices are fabricated from a combined structure, preferably a braided wire structure. [Background technology]

[0002] Occluders generally provide sufficient occlusion, allowing for minimally invasive procedures for a variety of structural cardiac or vascular diseases. When implanted, interatrial shunt devices, such as AFRs, allow controlled flow across the device; see, e.g., WO 2016 / 038115 A1. Fistula devices can provide a passageway between two body cavities. Vascular plugs can provide vascular occlusion. Interventional procedures for the treatment of structural cardiac or vascular disease using endovascular and / or cardiac occluders and devices have become established routine.

[0003] An occluder for treating structural heart disease may have one disc at one end of the device, or two discs, one at each end of the waist. The discs may have an enlarged diameter relative to the waist. Typically, the discs are used as the occluding portion of the occluder.

[0004] An occluder with two discs may extend between two sides of a cardiac structure, such as the septum, a heart valve, or a valve annulus, or between two blood vessels, such as the pulmonary artery and aorta. A disc can be placed on each side of the cardiac structure, preferably as a holding unit to keep the occluder in place when implanted. The waist can extend through the cardiac structure, which can have great variability. For example, occluders with a single disc are commonly used to accommodate great variability in anatomical structure length and shape for the treatment of some diseases. For single-disc occluders, either the disc or the waist can be used as the occluding portion. However, the anatomical structure may distort the occluding waist, distorting the occluding effect of the device. This can make it difficult to securely anchor the occluder to the anatomical structure.

[0005] In the case of anatomically adapted occluders designed for specific clinical / anatomical lengths, if an occluder with two discs is used in a situation where the extensible length of the waist is actually required, the disc may be distorted by the stiffness of the waist. This may reduce the quality of the occlusion provided by the disc. Other structural heart diseases are treated with fixed diameter occluders or with only a single disc.

[0006] WO 2017 / 139702 A1 discloses a vascular occlusion device having petals with varying pitch. U.S. Patent Publication No. 8,313,505 B2 discloses a tubular occluder with a single pitch. WO 2014 / 150288 A2 discloses a vascular treatment device that controls the braid angle to control the porosity of the device. WO 2018 / 058033 A1 discloses an LAA occluder having multiple layers of braid with different pitches. WO 2011 / 161136 A1 discloses a medical implant assembled from various braided segments. WO 97 / 42878 A1 discloses an occlusion device made of a tubular braid with a single pitch. European Patent Application Publication No. 2063791 and corresponding International Publication No. WO 2008 / 036156 A1 disclose a cerebrovascular device in which the braid angle of a tubular braid is controlled to limit expansion of certain portions of the device, but not at the ends of the device. International Publication No. WO 2014 / 110589 A1 discloses an occlusion device with a variable pitch, but does not disclose the purpose or function of the variable pitch in the device. International Publication No. WO 2017 / 214431 A1 discloses a braided vaso-occlusion element and a variable braid pitch, but does not disclose the purpose or function of the variable pitch in the device. International Publication No. WO 03 / 065934 A2 discloses a braided modular stent in which varying braid angles provide different radial strengths for the stent. International Publication No. WO 2018 / 112203 A1 discloses a stent with a polymeric electrospun coating. US Patent Application Publication No. US2015 / 238333 discloses a vascular aneurysm stent device.

[0007] Certain anatomical structures are not suitable for occlusion with any of the occluders described above.

[0008] Additionally, the length of the anatomical structure occluded by the constriction may change during the life of the implanted occluder. For example, the structure may expand in structural heart disease. Also, contractions may occur, for example, during sinus rhythm or fibrillation of the heart. For example, the atrial appendages may contract or expand. The heart wall may thicken. Generally, known occluders are unable to handle the tensions that create such changing anatomical conditions for the surrounding implant tissue, potentially leading to tissue rupture, unwanted leakage at the implant site, or even embolization of the device with dire consequences for the patient.

[0009] Therefore, there is a need for an occluder with increased bending resistance for treatment of anatomical structures with greater variability, such as length and / or shape. Summary of the Invention

[0010] Accordingly, as described above, embodiments of the present invention seek to preferably mitigate, alleviate or eliminate the defects, drawbacks or problems in the art singly or in any combination by providing an occluder as defined in the appended claims.

[0011] The present invention is defined solely by the appended claims, and in particular by the scope of the appended independent claims. References to "embodiments" throughout the detailed description that are not under the appended claims merely represent possible exemplary implementations and are therefore not part of the present invention. In one aspect, the present disclosure includes an occluder with a tubular interwoven structure having a pitch that varies along the axial length of the occluder, with at least one transition in the pitch being located closer to the central axis or intermediate member of the occluder than the outer circumferential surfaces of the proximal and / or distal elements when the occluder is in a relaxed state. The occluder is made of at least one wire unitary base body and includes a continuous tubular braided structure having a pitch that varies along the axial length of the base body with at least one pitch transition. The occluder is preferably heat-set to have a shape that, in the relaxed state of the occluder, includes a proximal retention element having an outer circumferential surface and a distal inner diameter at a first transition. The shape preferably includes a distal retention element having an outer circumferential surface and a proximal inner diameter at a second transition portion in the relaxed state of the occluder. The shape preferably includes an intermediate element extending between the first and second transition portions of the proximal and distal retention elements. At least one pitch transition from a first pitch to a second pitch is preferably located closer to the intermediate element or central axis of the occluder when the occluder is in the relaxed state than to the outer circumferential surface of at least one of the proximal and distal elements. Preferably, the location of at least one of the transition portions is closer to the central axis, and the diameter of the intermediate element decreases from its relaxed diameter when the occluder is in the axially extended state.

[0012] In another aspect, the present disclosure includes an occluder stretchable from a relaxed state to an axially stretched state, said occluder being longer in the longitudinal direction of the occluder than in the relaxed state, and wherein the load-to-elongation ratio provided by the occluder, measured in N / mm, is less than about 0.75 when stretched at least 2 mm. The first and second aspects form mutually exclusive embodiments or can be combined into a single embodiment.

[0013] In a second aspect of the present disclosure, a method of manufacturing an occluder is provided. The method includes forming a unitary platform body of at least one wire to provide a continuous tubular braided interwoven structure having a pitch that varies along the axial length of the occluder platform body with at least one pitch transition. The method includes heat-setting the platform body to have a shape that, in the relaxed state of the occluder, preferably includes a proximal retention element having an outer circumferential surface and a distal inner diameter at a first transition portion. The shape preferably includes a distal retention element having, in the relaxed state of the occluder, an outer circumferential surface and a proximal inner diameter at a second transition portion. The shape preferably includes an intermediate element extending between the first and second transition portions of the proximal and distal retention elements. At least one pitch transition from the first pitch to the second pitch is preferably located closer to the intermediate element or central axis of the occluder than to the circumferential surface of at least one of the proximal and distal elements when the occluder is in a relaxed state. Alternatively, or additionally, the occluder is stretchable from the relaxed state to a state that is axially elongated longer along the length of the occluder than in the relaxed state, wherein the load-to-elongation ratio provided by the occluder, measured in N / mm, is less than about 0.75 when stretched at least 2 mm without distortion of the proximal or distal retention elements.

[0014] An embodiment of the present invention provides an occluder including at least one wire and a tubular combined structure made from the at least one wire and having a pitch that varies along the axial length of the occluder, the occluder including a proximal element having an outer circumferential surface and an inner diameter in the relaxed state of the occluder, a distal element having an outer circumferential surface and an inner diameter in the relaxed state of the occluder, and an intermediate element extending between the proximal and distal elements.

[0015] According to a first aspect, at least one transition of the pitch from the first pitch to the second pitch is located closer to the intermediate element or central longitudinal axis of the occluder than to the circumferential surface of at least one of the proximal and distal elements when the occluder is in a relaxed state.

[0016] According to a second aspect, the occluder is longitudinally extensible from a relaxed state to an axially elongated or elongated state that is longer in the longitudinal direction of the occluder than the relaxed state, and the load-to-extension ratio provided by the occluder, measured in N / mm, is less than about 0.75 when elongated at least 2 mm.

[0017] In various embodiments, the first and second aspects are mutually exclusive embodiments or may be combined into a single embodiment. Each of the first and second aspects, separately or together, may be combined with the next embodiment.

[0018] In one embodiment, when the occluder is in a relaxed state, at least one transition in pitch may be located between the outer periphery and the inner diameter of at least one of the proximal and distal elements.

[0019] In one embodiment, at least one of the proximal and distal elements includes at least a first pitch, and the intermediate element includes only a second pitch along the axial length of the intermediate element.

[0020] In one embodiment, at least one of the outer periphery of the proximal and distal elements remains substantially constant as the inner diameter decreases upon longitudinal stretching of the occluder.

[0021] In one embodiment, at least one of the proximal and distal elements includes only the first pitch.

[0022] In one embodiment, the intermediate element includes a first pitch and a second pitch along the axial length of the intermediate element.

[0023] In one embodiment, the occluder is expandable from a relaxed state to a state that is axially elongated in the longitudinal direction of the occluder greater than the relaxed state.

[0024] In one embodiment, the load to elongation ratio provided by the occluder, measured in N / mm, is preferably less than 0.5 N / mm, preferably less than 0.75 N / mm, and more preferably less than 0.25 N / mm when stretched at least 2 mm up to about 6 mm.

[0025] In embodiments, when the occluder is stretched from the relaxed state to the extended state, the cross-sectional diameter of the intermediate element decreases by less than 60%, preferably less than 40%.

[0026] In embodiments, the outer periphery of at least one of the proximal and distal elements is substantially constant when the occluder is stretched to a length greater than 50% of its relaxed state and up to about 150% of its relaxed state.

[0027] In embodiments, when the occluder is in a relaxed state, the intermediate element is at least partially straight or has a centrally waisted shape relative to the longitudinal axis of the occluder, such as a cylindrical or conical, bell-shaped, or hourglass-shaped shape.

[0028] In embodiments, the occluder is one of an interatrial shunt device, such as, for example, a PDA occluder, a PLD, a TAVI-PLD, a VSD occluder, an atrial septal defect (ASD) occluder, a patent foramen ovale (PFO) occluder, an LAA occluder, an AFR (atrial flow regulator), a fistula device, or a vascular plug (VP) device.

[0029] Embodiments of the present invention provide an occluder that can be used to occlude anatomical structures having a wide variety of shapes, thereby eliminating the need for surgical occlusion, which was previously the only available option. In particular, the extensibility of the present invention provides an occluder that can conform to a wide variety of shapes and is therefore highly flexible. For example, an occluder may provide occlusion with proximal and distal elements at each end of an intermediate element when used with the proximal and / or distal elements expanded relative to the waist between them. Occlusion may be enhanced by appropriate coatings and / or fabric patches known to those skilled in the art.

[0030] The term "comprises / comprising", when used in this specification, is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. [Brief explanation of the drawings]

[0031] These and other aspects, features, and advantages possible from embodiments of the present invention will become apparent and elucidated from the following description of embodiments of the invention, now referring to the accompanying drawings. [Figure 1a] FIG. 1a is a side view of an embodiment of a base body with an example of the basic shape of the tubular interlocking structure prior to heat setting into a loosened occluder 1. FIG. [Figure 1b] FIG. 1b is a side view of the base body of FIG. 1a with an example relative representation, in which a portion of the base body is positioned in an occluder 1 when given a desired shape by a suitable heat-setting process; [Figure 2a] FIG. 2a is a side view and a cross-sectional view, respectively, taken through the center of an embodiment of an occluder, looking across its longitudinal direction towards its proximal and distal ends when the occluder is in a relaxed state. [Figure 2b] FIG. 2b is a perspective view of the occluder of FIG. 2a in a relaxed state. [Figure 3a] FIG. 3a is a side view and cross-sectional view taken through the center of the occluder of FIG. 2a looking across the longitudinal direction toward the proximal and distal ends when the occluder is in an axially stretched or elongated state. [Figure 3b] FIG. 3b is a perspective view of the occluder of FIG. 2a in an axially stretched or elongated state. [Figure 4a] FIG. 4a is a side view and a cross-sectional view, respectively, taken through the center of an embodiment of an occluder, looking across its longitudinal direction towards its proximal and distal ends when the occluder is in a relaxed state. [Figure 4b] FIG. 4b is a perspective view of the occluder of FIG. 2a in a relaxed state. [Figure 5a] 5a is a side view and a cross-sectional view taken through the center of the occluder of FIG. 4a looking across the longitudinal direction toward the proximal and distal ends when the occluder is in an axially stretched or elongated state; and [Figure 5b] FIG. 5b is a perspective view of the occluder of FIG. 4a in the axially stretched or elongated state shown in FIG. 5a. DETAILED DESCRIPTION OF THE INVENTION

[0032] Specific embodiments of the present invention will be described with reference to the accompanying drawings. However, because the present invention can be embodied in many different forms, it should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention, as defined by the appended claims, to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting. In the drawings, like numerals refer to like elements.

[0033] This description of the invention is given with respect to occluder 1, which is illustrated in the embodiment of a PDA occluder. Other occluders of the present disclosure have similar shapes and functions, e.g., VSDs, such as mVSD (muscular ventricular septum) occluders with the improvements of the present disclosure, where a conventional mVSD is described below for comparative measurements with an occluder without the improvements. However, it should be kept in mind that the present invention is not strictly limited to the illustrated embodiments, but includes additional embodiments such as other types of occluders, such as PDA occluders, PLDs, TAVI-PLDs, VSD occluders, atrial septal defect (ASD) occluders, patent foramen ovale (PFO) occluders, LAA occluders, inter-atrial shunt devices such as AFRs (atrial flow regulators) that allow inhibited left / right cardiac blood flow across the atrial wall, fistula devices, or vascular plug (VP) devices, and occluders that form fistula channels (occluding or directing at least partial flow across the fistula).

[0034] The present invention will be described with respect to a first aspect and a second aspect and their embodiments. The first aspect and the second aspect are mutually exclusive embodiments. In some embodiments, the first aspect and the second aspect are combined into a single embodiment, which may be further defined by the detailed embodiments described herein. Structures common to the first aspect and the second aspect will be described first.

[0035] As illustrated in FIGS. 1a and 1b, the substrate of the occluder 1 includes at least one wire 2 and can be formed into a tubular interlocking structure 3 (FIG. 1a) made from at least one wire 2. The substrate can be made from a single, integral, continuously interlocking structure 3, such as a single braid with two opposing ends. The interlocking structure 3 can also be made from a single wire. The wire 2 can also be referred to as a strand. The wire can be made of metal. The wire can be made of a suitable polymeric material. The strand can be made as a single-core heavy filament or can be made of sub-elements forming a strand (multifilament), such as a braided multifilament strand similar to strand technology. The wire 2 can be made of a shape memory material, such as a shape memory metal (e.g., nitinol). In particular, the wire 2 can be made of a shape memory material with highly elastic properties.

[0036] The tubular interlocked structure 3 is typically interlocked by a weaving technique. Preferably, the tubular interlocked structure 3 is woven to provide the tubular interlocked structure 3 as a tubular braid. The tubular braid may be provided by known braiding techniques. However, portions of varying pitch and / or elasticity are provided by the improvements disclosed in this application. A preferred example of a braiding technique for a pouch-shaped substrate with a single pitch is disclosed in International Application No. US2007 / 0225760A1, which is owned by the same applicant as the present application and is incorporated herein by reference in its entirety for all purposes. Those skilled in the art will know how to modify the teachings of International Application No. 2007 / 0225760A1 to produce a substrate body according to the improvements disclosed in this disclosure.

[0037] The wires of the tubular interlocking structure 3 are assembled to have a pitch, which is the longitudinal distance required for one rotation of the wires around the tubular interlocking structure 3. As can be seen in FIGS. 1a and 1b, the pitch may vary along the axial length of the occluder 1. In the first portion 3a, the pitch may be greater than the pitch of the second portion 3b. This provides for varying the extensibility or elasticity of the tubular interlocking structure 3 along its length. The first, second (and even, e.g., third) portions of the tubular interlocking structure 3 may thus be given different extensibility (stretchability) by varying the pitch. For example, the first portion may be given a pitch such that it is not as extensible (stretchable) as the second portion 3b. The third portion (if present) may be given a different pitch than the first portion 3a or the second portion 3b. In one example, the third portion may be given the same pitch as the first portion 3a. Further portions may be defined by varying the pitch of the portions relative to other portions of the base body of the tubular interlocking structure 3.

[0038] For example, the pitch of the wire (i.e., the angle defined between the turns of the wire and the axis of the combined structure) and the picks (i.e., the number of wire overlaps per unit length) of the tubular combined structure 3 can be adjusted as desired for a particular application. For example, the wire pitch can be about 90 degrees to 130 degrees, e.g., about 100 degrees. Also, by way of example, when the occluder 1 is in a relaxed configuration, the number of picks in the second portion 3b can be about 7 to 12 picks / 5 mm, e.g., about 9 picks / 5 mm. When the occluder is stretched about 4-6 mm, the pitch of the wires can be about 50-90 degrees and / or the number of picks in the second portion 3b can be about 12-16 picks / 5 mm, for example about 14 picks / 5 mm. At the same time, the pitch and / or picks of the first portion 3a of the thermoformed occluder 1 can be constant in both the relaxed and extended shapes. Alternatively, or in addition, the wires of the first portion 3a can combine to form a petal-like shape. Thus, when the occluder is in the relaxed shape as well as the extended state, the picks of the first portion 3a can be essentially constant, while the second portion has variable picks in the relaxed shape relative to the extended state.

[0039] Figure 1a illustrates a tubular interlocked structure 3 made of a braid of multiple wires in its basic shape before heat treatment and before forming the occluder 1 into its relaxed shape. Additionally, the interlocked structure 3 of Figures 1a and 1b illustrates an embodiment in which the base body includes a first portion 3a and a second portion 3b, with the first portion 3a distal to the second portion 3b. When the portions have varying (varying) pitch, a pitch transition 9 exists between the portions.

[0040] In other embodiments, the structure 3 combined with the base body includes a third portion (not shown in FIG. 1 a or 1 b) formed proximal to the second portion 3 b. The third portion may have a pitch different from, for example, a pitch greater than, the pitch of the second portion 3 b. In other embodiments, the pitch of the third portion is smaller than that of the second portion 3 b.

[0041] Thus, other embodiments may have additional portions.

[0042] Then, after heat-setting the relaxed shape of the occluder 1, the heat-set occluder 1 has the same portion defined by the base body along its longitudinal axis. The portion of the structure 3 assembled to the base body may not correspond one-to-one to the portion of the heat-set occluder. For example, the pitch transition 9 is secured along the base body and therefore along the heat-set occluder 1. However, as described in more detail below, the transition from an occluder element, such as the end disc 6, to an adjacent occluder element, such as the middle portion 8 at transition 9b (also referred to as the "waist" of the occluder), may occur at a different transition or location 9a, 9b along the longitudinal axis of the heat-set occluder than the pitch transition 9. The location of the transitions 9a, 9b along the longitudinal axis and / or axial position of the occluder 1 may further vary. For example, the variability in the location of the transitions 9a, 9b may be determined by the state of elongation of the occluder 1. See below.

[0043] Thus, elements of occluder 1, such as discs 4 and 6, may have two or more sections with different pitches (such as 3a and 3b) along their length. For example, an inner disc portion, such as distal disc 6, of a double-folded disc may include a pitch transition 9 between portions of the base body, while transition 9b to waist 8 may be positioned more inward toward central axis 10 of occluder 1, as can be seen in Figures 2-5.

[0044] Furthermore, the position of the transitions 9a, 9b may vary, see for example Figures 2a, 2b and 3a, 3b and 4a, 4b and 5a, 5b respectively.

[0045] The length of the waist 8 can therefore vary partly thanks to the variable position of the transitions 9a, 9b and partly thanks to the different pitch of the first and second portions 3a, 3b.

[0046] Moreover, the extensibility (stretchability) or elasticity of the waist 8 may be selected to further encourage elongation of the waist prior to deformation of the edge and / or outer diameter of the disc, see below.

[0047] In some embodiments, the pitch of the first portion 3a and the third portion are the same, which provides for essentially equal force application to the second portion 3b when the occluder 1 is stretched or lengthened, as described below. In other embodiments, the first portion 3a and optionally the third portion may be formed by petal-shaped wires, as illustrated in Figures 4b and 5b. Such shapes may also be utilized in the embodiments illustrated in Figures 2b and 3b.

[0048] The combined structure 3 of Figure 1a forms the shape of the occluder in its relaxed or unelongated state, and forms a basic shape that can be heat treated in one or more steps to obtain the occluder's properties as further described below. Heat treatment of shape memory materials such as Nitinol is known as such and will not be described further herein. The relative positions of parts of an example occluder can be seen in Figure 1b.

[0049] In addition to varying pitch sections, the extensibility or elasticity of the tubular interlocked structure 3 can be further defined by the heat-setting process, which can be performed in sections with various parameters as would be known to one skilled in the art. The extensibility or elasticity can thus be defined to vary along the longitudinal axis of the heat-set occluder 1. For example, the middle element 8 can have a higher extensibility than one or two end portions, such as the disks 4 and 6.

[0050] After heat treatment, the occluder is generally self-expandable. When collapsed, for example during delivery in a catheter sheath, the occluder will resiliently return to its heat-set, relaxed shape without further restraint. The occluder can be fully or at least partially collapsed again and self-expand again. Preferably, a highly elastic material is provided, such as a wire strand, such as Nitinol.

[0051] 2a-2b illustrate the relaxed or unelongated state of the occluder. The occluder 1 may include a proximal element 4 having an outer circumferential surface 5 and an inner diameter D1a in the relaxed state of the occluder 1. Additionally or alternatively, the occluder 1 may include a distal element 6 having an outer circumferential surface 7 and an inner diameter D1b in the relaxed state of the occluder 1. An intermediate element 8 may extend between the proximal element 4 and the distal element 6.

[0052] In particular, the distal element 6 can be a distal retaining element. In particular, the proximal element 4 can be a proximal retaining element. Retaining means the ability to keep the occluder 1 in place when implanted. For example, the retaining element can be a retaining disc.

[0053] Each of the proximal element 4 and distal element 6 may form a disc of the occluder 1 .

[0054] The occluder 1 comprises a proximal element 4 and / or a distal element 5, ie, a proximal disc and / or a distal disc.

[0055] The proximal 4 / distal elements 6 can be, for example, substantially circular, oval, substantially square, kidney-shaped (eg, for TAVI PLD), and the like.

[0056] Furthermore, the proximal and / or distal elements may be cup-shaped, i.e., their periphery may be curved in the proximal and distal directions of the occluder 1 .

[0057] Additionally, the proximal / distal elements may be dome-shaped (convex outer surface at the end surface).

[0058] In some embodiments, the proximal elements 4 and / or the distal elements 6 are bent from their centers. In other embodiments, only a portion of the proximal elements 4 and / or the distal elements 6 are bent.

[0059] Furthermore, the proximal / distal elements may additionally and / or alternatively be provided with recesses to "hide" the connecting elements, such as welded or clamped ends of wires, and to prevent them from protruding beyond the end surface, thus providing improved endothelialization and / or reduced risk of thrombosis for attachment to the occluder surface when implanted.

[0060] The intermediate member 8 may form a waist of the occluder 1. The maximum outer diameter of the intermediate member 8 may be smaller than the maximum outer diameters of the proximal and distal elements 4, 6.

[0061] In some embodiments, intermediate member 8 includes a first pitch and a second pitch along the axial length of intermediate member 8. Additionally, as seen in Figures 2b and 3b, intermediate portion 8 may have a pitch that varies along its length, such as one or several portions with a larger pitch and a smaller pitch along its length. This further enhances the elastic properties of intermediate portion 8. The intermediate portion 8 in one example has substantially more elasticity in the longitudinal direction of the occluder than the proximal and distal elements 4, 6.

[0062] According to a first embodiment, when the occluder 1 is in a relaxed or non-elongated state, at least one pitch transition 9 from a first pitch to a second pitch is positioned closer to the inner diameter D1 and / or central axis 10 of the occluder 1 than the outer peripheral surface 5, 7 of at least one of the proximal and distal elements 4, 6. The pitch transition 9 occurs at an inner disk portion (oriented away from the end of the occluder and toward the longitudinal middle and / or center of the occluder) of the double-folded distal element, which in one example has the shape of a disk element. The distal element may have an outer diameter or axial surface. The pitch transition 9 is positioned closer to the inner diameter D1 and / or central axis 10 of the occluder than the outer peripheral surface 5, 7. This contributes to a higher extensibility or resilience of the intermediate member 8 than at least one of the proximal and distal elements 4, 6.

[0063] According to a second embodiment, the occluder 1 can be extended or stretched from a relaxed state to an axially stretched state, the stretched state being longer in the longitudinal direction of the occluder than the relaxed state. The occluder 1 can have a load-to-stretch ratio measured in N / mm. The load-to-stretch ratio can be measured as described below. When the occluder is stretched or extended at least 2 mm in the axial direction along the center or longitudinal direction 10 of the occluder 1, the load-to-stretch ratio provided by the occluder 1 can be less than about 0.75 N / mm. This load-to-stretch ratio for this length stretch / occluder-extension range can be provided without substantially distorting the proximal and / or distal elements 4. When the disc shape is maintained and / or its outer diameter / periphery is not altered from its relaxed, heat-set shape, the proximal and / or distal elements 4 are generally not distorted. Thus, retention is provided by the distal elements to allow the occluder 1 to remain in place when implanted over a large range. This ratio therefore defines a higher extensibility (stretchability) or elasticity of the intermediate member 8 than at least one of the proximal element 4 and the distal element 6, respectively. Thus, the occluder 1 is advantageously adaptable to anatomical variations even during (long-term) implantation while maintaining retentiveness (as the proximal element 4 and / or the distal element 6 are not distorted). When further stretched, beyond the end of its axially stretched range, the occluder may distort its shape (which is sometimes desired, for example, when folding the occluder into a delivery sheath for implantation).

[0064] In the following, embodiments will be described that combine only the first aspect, only the second aspect, or the first and second aspects in combination.

[0065] In some embodiments, the load-to-strain ratio provided by occluder 1 is less than 0.5 N / mm, preferably less than 0.75 N / mm. In some embodiments, it may even be less than 0.25 N / mm. The load-to-strain ratio is provided when occluder 1 is stretched or extended to a predetermined longitudinal length. The predetermined length may be, for example, at least 2 mm and up to about 6 mm. Occluder 1 is highly stretchable over a greater range than conventional devices before the aforementioned strains occur.

[0066] FIG. 2a shows a side view of occluder 1 (central view) and a cross-sectional view taken across intermediate portion 8, a view looking toward proximal element 4 (bottom view), and a view looking toward distal element 6 (top view). FIG. 3a includes a similar view looking at occluder 1 in an extended state. Each of proximal element 4 and distal element 6 may be formed by a bilayer of interdigitated structure 3, with the outer edge of the bilayer forming outer diameter 5 or outer periphery 7, respectively. Thus, as illustrated in the bottom view of FIG. 2a, transition portion 9a of proximal element 4 may be positioned distal to proximal element 4. Similarly, as illustrated in the top view of FIG. 2a, transition portion 9b of distal element 6 may be positioned proximal to distal element 6.

[0067] As can be seen in the figure, the transition portions 9a, 9b may have an axial position (distance to the longitudinal central axis 10) that may vary depending on the elongation state of the occluder 1, while the outer diameter 5 or outer peripheral surface 7 remains substantially constant as the occluder 1 is stretched within its large elongation / extension range.

[0068] Overall, the occluders of the present disclosure avoid transitions with reduced diameters. In certain embodiments, the occluders do not have transitions with reduced diameters. In particular, the occluders do not have transitions between end elements, such as distal element 6 or proximal element 4, and intermediate element 8. The varying pitch and / or portions of the flexible fabric improve the flex resistance of the occluder portions relative to one another. Notably, not only is stretchability better than conventional devices, but potential improvements in pivoting or tilting movement of the occluder relative to one another are provided by the arrangement between braid pitch transitions and the relative positions of transitions 9 a, 9 b between the occluder elements. While transitions with reduced diameters may be omitted in this manner, they may be present in some embodiments.

[0069] In some embodiments, at least one transition 9 of the pitch is located between the outer peripheral surfaces 5, 7 and the inner diameter D1a, D1b of at least one of the proximal and distal elements 4, 6 when the occluder 1 is in a relaxed state.

[0070] For example, at least one of the proximal element 4 and the distal element 5 can include at least a first pitch. The intermediate element 8 can include a second pitch only along the axial length of the intermediate element 8. Thus, the intermediate element 8 can, in one example, be formed only from the second portion 3b of the combined tubular structure 3. Similarly, the proximal element 4 and / or the distal element 5 can be formed only from the first portion 3a / third portion of the combined structure 3.

[0071] Thus, the transition section 9 may bridge the intermediate element 8 and the proximal element 4 / distal element 6. Thus, in some embodiments, at least one of the proximal element 4 and the distal element 6 includes only the first pitch.

[0072] Figures 3a - 3b illustrate the extended or elongated state of the occluder 1. In this state, the axial length of the occluder 1 is extended or elongated. In this state, the middle portion 8 of the occluder is extended / elongated. The occluder is extended longitudinally. However, the axial length or thickness in the longitudinal direction of the proximal element 4 and / or the distal element 6 remains substantially constant without being distorted. Further, the inner diameter D3 of the middle element 8 in the elongated state of the occluder 1 is reduced compared to the relaxed state. On the other hand, the outer peripheral surfaces of the proximal element 4 and / or the distal element 6 remain substantially constant without being distorted. When L2 > L1, D3 < D2, but D1 remains substantially unchanged. This is due to the variation in the rigidity of the middle element 8 and the proximal element 4 and / or the distal element 6, and thus their stretchabilities are different.

[0073] As illustrated in FIGS. 2a - 3b, when the inner diameters D1a, D1b are reduced when stretching or elongating the occluder 1 along its longitudinal direction or central axis 10, at least one of the outer peripheral surfaces 5, 7 of the proximal element 4 and the distal element 6 is substantially constant respectively. This is provided, for example, by providing varying pitches for the first part 3a, the second part 3b, and optionally the third part of the combined tubular structure 3.

[0074] In some embodiments, when the occluder is extended from the relaxed state to the extended state in terms of axial length, the diameter of the cross - section of the middle element 8 reduces by less than 60%, preferably less than 40%, from diameter D2 to diameter D3 without the above - mentioned distortion occurring.

[0075] Similarly, in some embodiments, when the occluder 1 is extended or elongated from the non - extended or slack length L1 to a length L2 that exceeds 50% of the relaxed state and up to approximately 150% of the maximum of the relaxed state in terms of length, the outer periphery or diameter 7 of at least one of the proximal element 4 and the distal element 6 is substantially constant.

[0076] In the embodiment illustrated in Figures 2a-2b, intermediate element 8 is at least partially straight or waisted in a shape such as a cylinder or cone. However, in other embodiments, when occluder 1 is in a relaxed state, intermediate element 8 assumes a bell-shaped or hourglass-shaped configuration relative to the longitudinal or central axis 10 of occluder 1. The shapes of proximal and / or distal elements 4 and / or 6 and the shape of intermediate portion 8 can be formed by one or several molds using the same or different temperatures during heat treatment in one or more steps and during heat treatment of the shape memory material. Those skilled in the art will select the appropriate curing temperature and setting time and heat-setting distribution to obtain the desired device as disclosed herein, depending on the actual material selected for occluder 1, the selected pitch and its distribution along the base body, the distribution of occluder elements along the longitudinal axis of the occluder, and the flexibility or stiffness of the fabric in the desired portion of occluder 1. This contributes to the elasticity of the intermediate element 8, as described above, being greater compared to at least the outer sides oriented toward the ends of the occluder 1 of the proximal element 4 and the distal element 6. The intermediate element can thus be heat-set to have a softer weave than the elements 4, 6. The intermediate element 8 can have portions with both a first pitch and a second pitch. Such an intermediate element can have a softer weave than adjacent elements upon heat setting. Thus, the intermediate element 8 can have two portions with pitches that have the same braided flexibility / elasticity / stretchability that differs from the braided flexibility / elasticity / stretchability of the adjacent elements 4, 6. The distal element 6 and / or the proximal element 4 can have portions with both a first and a second pitch. The first pitch can be the same as the third pitch. After heat setting, the occluder 1 is removed from the molding element and substantially retains its relaxed shape after being deformed.

[0077] At least one end of the occluder 1 may include an attachment element 11 for attaching the occluder 1 to a delivery device for catheter-based delivery. The attachment element 11 may be a joint, such as a laser welded joint. In the illustrated embodiment, the base body of the assembled structure 3 is pouch-shaped; that is, the wires 2 originate at the proximal end, are assembled to the distal end, and then are assembled back to the proximal end. In other embodiments, the assembled structure 3 is tubular with attachment elements, such as clamps, that bind the free ends of the wires 2 at each end. The attachment element 11 for attaching the occluder 1 may be located on the central axis 10 of the occluder 1. The attachment element 11 for attaching the occluder 1 may also be located off-center from the central axis 10, such as on the AFR. International Publication No. WO 09 / 016265 A2, which has the same applicant as the present application and is incorporated herein by reference in its entirety for all purposes, discloses a manufacturing method in which the free ends of wire 2 are bundled and fixed at both ends. Thus, in such an embodiment, one end of wire 2 is positioned at the distal end of the occluder and the other end of wire 2 is positioned at the proximal end of occluder 1 (not shown).

[0078] Figures 4a-4b and 5a-5b illustrate an embodiment with alternative shapes of the outer periphery of the proximal element 14 and the distal element 16. The intermediate element 8 has the same shape as described with respect to Figures 2a-3b. Furthermore, the proximal element 14, the distal element 16, and the transition portions 9a, 9b to the intermediate element 8 may be designed as described with respect to Figures 2a-3b. The proximal element 14 and the distal element 17 have a first diameter D1 and a second diameter D5 as illustrated. Accordingly, elements having the same configuration as described with respect to Figures 2a-3b have the same reference numerals.

[0079] The embodiment illustrated in Figures 4a-4b and 5a-5b is, for example, a PVL occluder. PVL occluders and thickened shapes are disclosed in International Publication No. WO 2013 / 041721, which is co-owned by the present application and is incorporated herein by reference in its entirety for all purposes. The discs and waists of the PVL devices of WO 2013 / 041721 may be advantageously provided with the improvements described herein. However, disc 16 or disc 14 has concavely curved portions and convexly curved outer peripheral surfaces 5, 7 on opposing axial portions of the disc. This is particularly advantageous when the concavely curved portions are apposed to or adjacent to a prosthetic valve upon implantation. The convexly curved opposing outer peripheral surfaces provide anatomical advantages in certain target regions for conveniently holding the PVL occluder in place while providing advantageous occlusion of paravalvular leaks.

[0080] In yet another embodiment, the occluder has a single proximal element, such as for an LAA occluder. The intermediate element may be formed by a combined structure and form a lobe, such as a cylinder, having a diameter no greater than that of the intermediate element. As described with respect to Figures 2a-3b, the intermediate element or lobe may be telescopic. Hooks may be attached to distal element 6 (if present) and / or intermediate element 8 to engage an anatomical structure, such as the LAA. After the hooks engage the vessel wall, the intermediate structure may be stretched and the proximal element may be positioned outside the anatomical structure. The telescopic nature of the intermediate element and / or lobe allows the occluder to be more flexible and conform to the shape of the anatomical structure, improving occluder performance.

[0081] LAA occluders are disclosed, for example, in commonly owned International Publication No. WO2019197569, which is incorporated herein by reference in its entirety for all purposes. The LAA devices disclosed in WO2019197569 can advantageously provide a waist and disc, along with the improvements described in the present disclosure.

[0082] In embodiments, the LAA occluder may further alternatively or additionally have a distal coupling element for the hook described above. Such an LAA occluder is disclosed, for example, in commonly assigned U.S. Patent No. 8,100,938, which is incorporated herein by reference in its entirety for all purposes. The LAA device disclosed in U.S. Patent No. 8,100,938 can advantageously provide a waist and disc, along with the improvements described in this disclosure.

[0083] The AFR device allows for controlled flow across the occluder during implantation. See, for example, International Publication No. WO 2016 / 038115, which is owned by the same applicant as the present application and is incorporated herein by reference in its entirety for all purposes. The AFR device disclosed in WO 2016 / 038115 can advantageously provide a waisted portion and a disk, along with the improvements described in this disclosure. The occluder 1 can have a through channel as shown and described in WO 2016 / 038115, such as through channel 106 in the drawings and description of WO 2016 / 038115. The attachment element 11 for attaching the occluder 1 can also be provided off-center from the central axis 10 as disclosed in WO 2016 / 038115, and the base body 3 can be provided with appropriate channels upon heat setting to provide an AFR according to the present disclosure. A dual-layer disc is shown, for example, in Figure 4c of International Publication No. WO 2016 / 038115 and the corresponding detailed description. These specific AFR elements are incorporated herein by reference. The first pitch portion 3a can be part of the inner layer of one or both of the folded dual-layer discs. This provides an advantageous occluder 1 in one example of an AFR device herein.

[0084] The load to elongation ratio can be determined using a tensile tester such as a tensile tester using AMETEK Sensorl, Test & Clibration, Instrument Number 10017 and Brand Lloyd Instruments. The test procedure includes: - Attaching one end of the occluder 1 to a fixed control and the other end of the occluder 1 to a tensile tester. - Using a tensile tester, stretch the neck of the occluder to 3N, with a tensile test speed of 600mm / min. 3N is chosen as the maximum applicable force to demonstrate the stretchability of the occluder with low force. - recording the amount of stretch or elongation of the occluder without distorting the shape of the proximal and / or distal elements. - Releasing the tension applied to the occluder and observing the reversibility of the stretching behavior, i.e. the device returns to its original shape without deformation after the tension is released.

[0085] The following table illustrates test embodiments A and B that fall within the ranges D1, D2, D3, L1, and L2 described above:

[0086] [Table 1]

[0087] The test method was defined above and applied to embodiments A and B, using the Occlutech® mVSD occluder (size 4), product number 71VSD04, as a control. The 71VSD04 mVSD occluder is made from a single-pitch base body. The overall shape of embodiments A and B corresponds to the shape illustrated in Figures 2b and 3b. Accordingly, embodiments A and B have proximal and distal elements formed as discs and an intermediate element in the form of an extensible waist. The disc shape is circular. The mVSD occluders exhibit a similar overall shape but with more uniform and conventional elasticity. That is, the elasticity of the intermediate element is similar to that of the proximal and / or distal elements and is made from a single-pitch braid. The intermediate element or waist is 4 mm in diameter, the proximal and distal elements (discs) are 10 mm in diameter, and the waist or intermediate element is 7 mm high.

[0088] The stretch behavior of embodiments of the present invention for mVSD devices is illustrated in the table below.

[0089] [Table 2]

[0090] The test samples have the same raw materials and sterilization methods. The braid and heat-set pitches vary for the mVSD occluders between embodiments A and B. There are numerous combinations of braid patterns and heat-sets that can be applied to achieve the above properties, all within the scope of the disclosure as set forth above with respect to the embodiments of the present invention.

[0091] As can be seen from the table above, embodiments of the present invention can be stretched or extended to greater lengths than conventional devices. In particular, this test demonstrates that occluders according to embodiments of the present invention can be stretched or extended in a recoverable manner, i.e., without distorting the original shape of the device, such as its length or disc diameter, after extension.

[0092] When the applied load is 3N, it is 100% to 150% When the applied load is 1N, the ratio is 50% to 100%.

[0093] This should be contrasted with regular occluders, exemplified by the mVSD occluder, which are characterized by being reversibly stretched or extended without distorting the original shape of the device, such as length or disc diameter after extension.

[0094] When the applied load is 3N, the ratio is 0% to 35%. When the applied load is 1N, the rate is 0% to 30%

[0095] It is also to be recognized that the features disclosed in the foregoing description, and / or the foregoing drawings, and / or the following claims, in any combination thereof, are material for realizing the invention in diverse forms thereof. When used in the following claims, the words "comprise," "include," "have," and their combinations mean "including but not limited to."

[0096] The present invention has been described above with reference to specific embodiments. However, other embodiments than those described are equally possible within the scope of the present invention. Various method steps other than those described above may be provided within the scope of the present invention. The various features and steps of the present invention may be combined in combinations other than those described. The scope of the present invention is limited only by the appended claims.

Claims

1. An occluder 1 is made of at least one unitary base body of wire and comprises a continuous tubular braided structure having a pitch, said pitch varying along the axial length of the base body with at least one pitch transition 9, said occluder comprising: a proximal retention element 4 having an outer circumferential surface and a distal inner diameter at a first transition portion 9a in a relaxed state of the occluder 1; a distal retention element 6 having an outer circumferential surface and a proximal inner diameter at a second transition portion 9b in the relaxed state of the occluder 1; an intermediate element 8 extending between the first transition portion 9 a and the second transition portion 9 b of the proximal retaining element 4 and the distal retaining element 6; where: at least one pitch transition 9 from a first pitch to a second pitch is located closer to an intermediate element or a central axis of the occluder than to the outer circumferential surface of at least one of the proximal and distal elements when the occluder is in a relaxed state; an occluder 1, characterized in that at least one of the transition portions 9a, 9b is close to the central axis 10 and the diameter of the intermediate element 8 decreases from its relaxed diameter when the occluder is in an axially extended state.

2. 2. The occluder (1) of claim 1, wherein the at least one transition (9) in the pitch is located between the outer periphery and the inner diameter of at least one of the proximal and distal retaining elements (4, 6) when the occluder (1) is in a relaxed state.

3. 3. An occluder (1) according to claim 1 or 2, characterized in that at least one of the proximal retaining element (4) and the distal retaining element (6) comprises at least the first pitch, and the intermediate element (8) comprises the second pitch only along its axial length.

4. An occluder (1) according to any one of claims 1 to 3, characterized in that at least one of the outer peripheral surfaces of the proximal retaining element (4) and the distal retaining element (6) remains substantially constant as the inner diameter decreases upon stretching the occluder.

5. 3. An occluder (1) according to claim 1 or 2, characterized in that at least one of the proximal and distal retaining elements has the same pitch, which is different from the pitch of the intermediate element (8).

6. 6. An occluder (1) as claimed in claim 1, 2 or 5, characterized in that the intermediate element (8) includes, along its axial length, a longitudinal portion having the first pitch and a longitudinal portion having the second pitch.

7. 7. An occluder 1 according to any one of claims 1 to 6, wherein the occluder is extensible from a relaxed state to an axially elongated state that is longer in the longitudinal direction of the occluder than the relaxed state, and wherein the load to elongation ratio provided by the occluder, measured in N / mm, is less than about 0.75 when elongated by at least 2 mm.

8. 8. An occluder 1 according to claim 7, characterised in that the load to elongation ratio provided by the occluder, measured in N / mm, is less than 0.5 N / mm, preferably less than 0.75 N / mm, and more preferably less than 0.25 N / mm when stretched to at least 2 mm and up to about 6 mm.

9. 9. An occluder (1) according to claim 7 or 8, characterized in that when stretched from a relaxed state to an extended state, the reduction in cross-sectional diameter of said intermediate element is less than 60%, preferably less than 40%.

10. An occluder 1 according to any one of claims 1 to 9, characterized in that the outer circumferential surface of at least one of the proximal and distal retention elements is substantially constant when the occluder is stretched to a length greater than 50% of its relaxed state and up to approximately 150% of its relaxed state.

11. An occluder 1 according to any one of claims 1 to 10, characterized in that when the occluder is in a relaxed state, the intermediate element is at least partly straight or centrally waisted relative to the longitudinal axis of the occluder.

12. 12. The occluder 1 according to any one of claims 1 to 11, characterized in that the occluder is a patent ductus arteriosus (PDA) occluder, a paravalvular leak device (PLD), a transcatheter aortic valve implantation PLD (TAVI-PLD), a ventricular septal defect (VSD) occluder, an atrial septal defect (ASD) occluder, a patent foramen ovale (PFO) occluder, a left atrial appendage (LAA) occluder, an interatrial shunt device, an atrial flow regulator (AFR) device, a fistula device, or a vascular plug (VP) device.

13. An occluder 1, a continuous tubular braided structure made of at least one unitary base body of wire and having a pitch that varies along the axial length of the base body with at least one pitch transition 9; The occluder is a proximal retention element 4 having an outer circumferential surface and a distal inner diameter at a first transition portion 9a in the relaxed state of the occluder 1; a distal retention element 6 having an outer circumferential surface and a proximal inner diameter at a second transition portion 9b in the relaxed state of the occluder 1; an intermediate element 8 extending between the first transition portion 9a and the second transition portion 9b of the proximal retaining element 4 and the distal retaining element 6; and heat-set to have a shape comprising where: - the occluder is stretchable from a relaxed state to an axially stretched state that is longer in the longitudinal direction of the occluder than the relaxed state, and the load-to-elongation ratio provided by the occluder, measured in N / mm, is less than about 0.75 when stretched at least 2 mm without distortion of the proximal or distal retention elements; an occluder 1, characterized in that at least one of the transition portions 9a, 9b is close to the central axis 10 of the occluder 1, and the diameter of the intermediate element 8 decreases from its relaxed diameter when the occluder is in an axially extended state.

14. 14. The occluder of claim 13, wherein at least one transition of the pitch from a first pitch to a second pitch is located closer to a central axis or intermediate element of the occluder than an outer circumferential surface of at least one of the proximal and distal retaining elements (4, 6) when the occluder is in a relaxed state.

15. 15. The occluder (1) of claim 14, characterized in that the at least one transition (9) in the pitch is located between the outer circumferential surface and the inner diameter of at least one of the proximal and distal retaining elements (4, 6) when the occluder (1) is in a relaxed state.

16. 16. An occluder 1 according to any one of claims 13 to 15, characterised in that the load to elongation ratio provided by the occluder, measured in N / mm, when stretched to at least 2mm up to about 6mm is less than 0.5N / mm, preferably less than 0.75N / mm, more preferably less than 0.25N / mm.

17. An occluder 1 according to any one of claims 13 to 16, characterized in that the reduction in cross-sectional diameter of said intermediate element when stretched from a relaxed state to an extended state is less than 60%, preferably less than 40%.

18. An occluder 1 according to any one of claims 13 to 17, characterized in that the outer circumferential surface of at least one of the proximal retaining element 4 and the distal retaining element 6 is substantially constant when the occluder 1 is stretched to a length greater than 50% of its relaxed state and up to approximately 150% of its relaxed state.

19. 19. The occluder 1 of any of claims 13-18, wherein the occluder is a patent ductus arteriosus (PDA) occluder, a paravalvular leak device (PLD), a transcatheter aortic valve implantation PLD (TAVI-PLD), a ventricular septal defect (VSD) occluder, an atrial septal defect (ASD) occluder, a patent foramen ovale (PFO) occluder, a left atrial appendage (LAA) occluder, an interatrial shunt device, an atrial flow regulator (AFR) device, a fistula device, or a vascular plug (VP) device.

20. An occluder (1) according to any of the preceding claims, characterized in that the distal retaining element (6) and / or the proximal retaining element (4) are disc-shaped.

21. 21. An occluder (1) according to claim 20, characterized in that the discs are double folded during heat setting, and the transitions (9) are respectively located on the inner layers of the discs.

22. An occluder (1) according to any of claims 13-19, characterized in that the distal retaining element (6) and / or the intermediate element (8) comprise hooks.

23. A method of manufacturing an occluder according to any one of claims 1 to 22, said method comprising: forming an integral base body of at least one wire providing a continuous tubular braided interlocking structure having a pitch that varies along the axial length of the occluder base body with at least one pitch transition (9); a proximal retention element 4 having an outer circumferential surface and a distal inner diameter at a first transition portion 9a in a relaxed state of the occluder 1; a distal retention element 6 having an outer circumferential surface and a proximal inner diameter at a second transition portion 9b in a relaxed state of the occluder 1; heat setting the base body to have a shape including an intermediate element 8 extending between the first transition portion 9a and the second transition portion 9b of the proximal retention element 4 and the distal retention element 6; where: at least one pitch transition 9 from a first pitch to a second pitch is located closer to an intermediate element or central axis of the occluder than to an outer circumferential surface of at least one of the proximal and distal retention elements when the occluder is in a relaxed state; or The method is characterized in that the occluder is stretchable from a relaxed state to an axially stretched state that is longer in the longitudinal direction of the occluder than the relaxed state, and the load-to-elongation ratio provided by the occluder, measured in N / mm, is less than about 0.75 when stretched at least 2 mm without distortion of the proximal or distal retention elements.

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