Thin-walled scaffolds

Abstract

To provide bioresorbable scaffolds for treating an anatomical lumen of the body.SOLUTION: A thin-walled scaffold includes a radiopaque marker 20 connected to a link. In a first example, the marker is retained on a strut 430a and a strut 430b by a head at one or both ends by swaging. In a second example of a thin-walled scaffold, the link is modified to avoid interference during crimping. In a third example, a distal end of the thin-walled scaffold is modified to improve deliverability of the thin-walled scaffold. These features are combined in a fourth example.SELECTED DRAWING: Figure 4D

Description

Technical Field

[0001]

[0001] The present invention relates to a bioabsorbable scaffold, and more particularly, to a bioabsorbable scaffold for treating an anatomical lumen of the body.

Background Art

[0002]

[0002] A radially expandable endoprosthesis is an artificial device adapted to be implanted into an anatomical lumen. The "anatomical lumen" refers to the lumen of a tubular organ such as a blood vessel, urinary tract, bile duct, i.e., a tube. A stent is an example of an endoprosthesis that is generally cylindrical, keeps a portion of an anatomical lumen open, and in some cases expands. Stents are often used in the treatment of atherosclerotic stenosis in blood vessels. "Stenosis" refers to the narrowing or constriction of the diameter of a body passage or opening. In such treatment, a stent reinforces the wall of a blood vessel and prevents restenosis after angioplasty in the vascular system. "Restenosis" refers to the recurrence of stenosis in a blood vessel or heart valve after treatment (by balloon angioplasty, stent placement, or valvuloplasty) and an apparent success.

[0003]

[0003] Treatment of an affected part or lesion using a stent involves both the introduction and deployment of the stent. "Introduction" refers to introducing and delivering a stent through an anatomical lumen to a desired treatment site such as a lesion. "Deployment" corresponds to the expansion of the stent within the lumen of the treatment area. The introduction and deployment of a stent are achieved by positioning the stent around one end of a catheter, inserting the end of the catheter into the anatomical lumen through the skin, advancing the catheter within the anatomical lumen to a desired treatment position, expanding the stent at the treatment position, and removing the catheter from the lumen.

[0004]

[0004] Scaffolds and stents are conventionally classified into two general categories, namely, balloon-expandable and self-expandable. The latter type expands (at least partially) within a blood vessel to a deployed or expanded state when radial constraint is removed, while the former utilizes an externally applied force to configure itself from a crimped or stored state to a deployed or expanded state.

[0005]

[0005] Self-expandable stents are designed to expand significantly when radial constraint is removed and often do not require a balloon for stent deployment. Self-expandable stents are stored within a sheath (with or without an auxiliary balloon) or do not undergo, or are relatively resistant to, plastic or inelastic deformation when expanded within a lumen. In contrast, balloon-expandable stents or scaffolds undergo significant plastic or inelastic deformation both when being crimped and when later being deployed by a balloon.

[0006]

[0006] In the case of balloon-expandable stents, the stent is attached around the balloon portion of a balloon catheter. The stent is compressed or crimped onto the balloon. Crimping can be achieved by using an iris-type or other form of crimper, such as the crimper disclosed and illustrated in U.S. Patent Application Publication No. 2012 / 0042501. A significant amount of plastic or inelastic deformation occurs both when the balloon-expandable stent or scaffold is being crimped and when later being deployed by a balloon. At the treatment site within the lumen, the stent is expanded by inflating the balloon.

[0007]

[0007] The stent must be able to meet several basic functional requirements. The stent (or scaffold) must be able to sustain a radial compressive force when supporting the vessel wall. Thus, the stent must have an appropriate radial strength. After deployment, the stent must maintain its size and shape appropriately over its service life despite the various forces that can act on the stent. In particular, the stent must appropriately maintain the vessel at a defined diameter over the desired treatment period. The treatment period may correspond to the period required for the vessel wall to remodel, after which the stent is no longer needed.

[0008] Examples of bioabsorbable polymer scaffolds include those described in Limon U.S. Patent No. 8,002,817, Lord U.S. Patent No. 8,303,644, and Yang U.S. Patent No. 8,388,673. FIG. 1 shows the distal region of a bioabsorbable polymer scaffold designed to be introduced through an anatomical lumen using a catheter and plastically expanded using a balloon. The scaffold has a cylindrical shape with a central axis 2 and includes a pattern of interconnected structural elements called bar arms or struts 4. Axis 2 extends through the center of the cylindrical shape formed by struts 4. The stresses involved during compression and deployment are widely distributed throughout struts 4 but concentrated at the bending elements, tops, or strut junctions. Struts 4 include a series of ring struts 6 connected to each other at tops 8. Ring struts 6 and tops 8 form a sinusoidal ring 5. Ring 5 is arranged longitudinally about axis 2. Struts 4 also include link struts 9 that connect rings 5 to each other. Rings 5 and link struts 9 collectively form a tubular scaffold 10 having axis 2, which represents the lumen axis or longitudinal axis of scaffold 10. Ring 5d is located at the distal end of the scaffold. Tops 8 form a smaller angle when scaffold 10 is crimped onto the balloon and a larger angle when plastically expanded by the balloon. After deployment, the scaffold receives static and cyclic compressive loads from the surrounding tissue. Ring 5 is configured to maintain the scaffold in a radially expanded state after deployment.

[0009]

[0009] The scaffold can be made from a biodegradable, bioabsorbable, bioreabsorbable, or bioerodible polymer. The terms biodegradable, bioabsorbable, bioreabsorbable, biodissolvable or bioerodible refer to the property of a material or stent that degrades, is absorbed, is reabsorbed, or erodes and disappears from the implantation site. The scaffold may also be constructed of bioerodible metals and alloys. In contrast to durable metal stents, the scaffold is intended to remain in the body for only a limited period of time. In many therapeutic applications, the presence of a stent in the body may be necessary for a limited period of time until its intended function, such as maintaining vascular patency and / or drug delivery, is achieved. Furthermore, biodegradable scaffolds have been shown to enable improved healing of the anatomical lumen compared to metal stents, which may lead to a reduced incidence of late thrombosis. In these cases, it is desirable to treat the blood vessels with a polymeric scaffold, particularly a bioabsorbable or bioreabsorbable polymeric scaffold, rather than a metal stent, so that the presence of the prosthesis in the blood vessel is temporary.

[0010]

[0010] In some of the following methods, polymer materials considered for use as polymer scaffolds, such as poly(L-lactide) (“PLLA”), poly(D,L-lactide-co-glycolide) (“PLGA”), poly(D-lactide-co-glycolide) with less than 10% D-lactide or poly(L-lactide-co-D-lactide) (“PLLA-co-PDLA”), poly(L-lactide-co-caprolactone), poly(caprolactone), PLLD / PDLA stereocomplex, and blends of the above polymers, may be described by comparison with the metal materials used for stent formation. Polymer materials typically have a lower strength-to-volume ratio compared to metals, meaning that more material is required to provide equivalent mechanical properties. Thus, in order for the stent to have the strength necessary to support the lumen wall at the desired radius, the struts must be made thicker and wider. Also, scaffolds made from such polymers tend to be brittle or have limited fracture toughness. The anisotropic and rate-dependent inelastic properties inherent in the material (i.e., the strength / rigidity of the material varies depending on the rate at which the material is deformed, in addition to temperature, degree of hydration, and thermal history) only exacerbate this complexity when acting with polymers, especially biodegradable polymers such as PLLA and PLGA.

[0011]

[0011] A further problem with using a bioabsorbable polymer (and generally a polymer consisting of carbon, hydrogen, oxygen and nitrogen) in a scaffold structure is that the material is radiolucent and not radiopaque. Bioabsorbable polymers tend to have X-ray absorption similar to body tissue. A known way to address this problem is to attach radiopaque markers to the structural elements of the scaffold, such as struts, bar arms, links, etc. For example, FIG. 1 shows a link element 9d that connects a distal end ring 5d to an adjacent ring 5. The link element 9d has a pair of holes. Each hole holds a radiopaque marker 11. There is a problem with the combined use of the marker 11 with the scaffold 10. A reliable way is needed to attach the marker 11 to the link element 9d so that the marker 11 does not separate from the scaffold during a processing step such as crimping the scaffold onto a balloon or when the scaffold is balloon-expanded from the crimped state. These two events, i.e., crimping and balloon expansion, are particularly problematic for marker attachment to the scaffold because both events induce significant plastic deformation in the scaffold body. If this deformation causes significant out-of-plane or irregular deformation of the struts that support or are near the marker, the marker may fall off (e.g., if the strut holding the marker is twisted or bent during crimping, the marker may fall out of its hole). Scaffolds with radiopaque markers and methods for attaching the markers to the scaffold body are discussed in U.S. Patent Application Publication No. 2007 / 0156230.

[0012]

[0012] There is a need to improve the certainty of fixing radiopaque markers to a scaffold for a thin-walled scaffold. In connection with this need, there is a need to improve the performance characteristics of thin-walled scaffolds made of bioabsorbable materials that must be passed around a scaffold, particularly an anatomical structure with a serpentine shape.

SUMMARY OF THE INVENTION

[0013] Disclosed is a bioabsorbable scaffold having a radiopaque marker and a scaffold structure that holds such a radiopaque material and enables improved catheter compliance when threading the catheter through an anatomical structure with a reduced crimp profile and / or with a scaffold to which a balloon is attached.

[0014] The scaffolds disclosed herein are suitable for meeting one or a combination of the following objectives. (i) Thinning the crimp profile of a thin-walled scaffold that supports a radiopaque marker. (ii) Securing the marker to the thin-walled scaffold. (iii) Reducing strain energy accumulation in the marker retention structure when the thin-walled scaffold is deformed during crimping, during balloon inflation at the target vessel site, or during introduction of the scaffold to the target site. (iv) Reducing the flare ring of the end ring at the distal end of the scaffold for a thin-walled scaffold or a scaffold that includes PLLA and has a wall thickness greater than 125 microns (μm).

[0015] In order to make the wall thin, it has been recognized through testing that it is necessary to modify certain critical areas of the scaffold that were not previously problematic when larger wall thicknesses were used. Examples of scaffolds having a wall thickness greater than 158 microns (μm) are described in U.S. Patent Application Publication No. 2010 / 0004735. When a significant reduction in wall thickness is made, it has been found that the arrangement, shape, and dimensions of the ring and link elements need improvement, particularly at the distal end of the scaffold, as compared to existing bioabsorbable scaffolds (e.g., from a wall thickness of 160 microns (μm) to 100 microns (μm)).

[0016]

[0016] A thin-walled scaffold is required because there is a clinical need to maintain a low profile of the struts exposed in the bloodstream. Blood compatibility, also called hemocompatibility or thromboresistance, is a desirable property for scaffolds and stents. The adverse events of scaffold thrombosis are very low-frequency events but are associated with high morbidity and mortality. To reduce the risk of thrombosis, dual antiplatelet therapy is administered with all coronary artery scaffold and stent implants. This is to reduce thrombosis due to the procedure, vascular injury, and the implant itself. Scaffolds and stents are foreign bodies, and they all have a certain degree of thrombogenicity. The thrombogenicity of a scaffold refers to its tendency to form thrombi, which is due to several factors including strut thickness, strut width, strut shape, total scaffold surface area, scaffold pattern, scaffold length, scaffold diameter, surface roughness, and surface chemistry. Some of these factors are interrelated. A low strut profile also leads to a reduction in neointimal hyperplasia. This is because the neointima will grow to the extent necessary to cover the struts. Thus, the coating is a necessary step for the completion of healing. It is thought that thinner struts result in faster endothelialization and healing.

[0017]

[0017] According to various aspects of the present invention, there are a thin-walled scaffold (the "scaffold"), a medical device, a method for fabricating such a scaffold, a method for fabricating a marker and attaching the marker to a strut, link, or bar arm of the scaffold, a method for crimping, or a method for assembling a medical device comprising such a scaffold, which have one or more of the following (1) to (15), or any combination thereof.

[0018] (1) The scaffold is crimped to a theoretically minimum crimp diameter (D-min).

[0019] (2) The scaffold wall thickness is less than 125 microns (μm), less than 100 microns (μm), about 100 microns (μm) or about 93 microns (μm).

[0020] (3) The wavelength of the ring connected to the marker link is greater than the wavelength of another ring not connected to the marker link, and / or the wavelength of the ring connected to the marker link has wavelengths of different lengths.

[0021] (4) The distance from the W top to the adjacent U top is greater than the distance from the Y top to the adjacent U top.

[0022] (5) The scaffold is made of a tube containing poly(L-lactide).

[0023] (6) A scaffold crimped to a balloon, the scaffold constituting a crimped state illustrated and described in connection with FIG. 4D, FIG. 6A or FIG. 7A.

[0024] (7) A method of crimping any of the scaffolds described in connection with FIGS. 3, 4, 5, 6, or 7.

[0025] (8) A method for attaching a radiopaque marker to a scaffold.

[0026] (9) A marker link illustrated and described in connection with FIG. 2C.

[0027] (10) The ring has n peaks, where n is greater than 5, or greater than 6 and less than or equal to 12.

[0028] (11) The ring has two wavelengths of a first size and n - 3 wavelengths of a second size, and the first size is greater than the second size.

[0029] (12) The ring connected to the marker link at the top of W has a first width, and the ring adjacent to the one connected to the marker link has a second width greater than the first width.

[0030] (13) The ring connected to the marker link at the top of W has a flat portion wider than the flat portion of the Y top connected to the marker link and joined to the first ring.

[0031] (14) The first distance between the marker link and the adjacent ring is greater than the second distance between the rings joined by the marker link.

[0032] (15) The first distance between the rings joined by the non-linear link marker link is greater than the second distance between the rings not joined by the non-linear marker link.

[0033] (16) D-min is about 1 mm or less than 1 mm.

[0034] (17) The aspect ratio (AR) of the marker link of the thin-film scaffold is about 4 - 5, or about 4.5, and AR is defined as the maximum width of the marker link divided by the wall thickness in the marker link.

[0035] (18) The first wavelength or half-wavelength of the first ring is greater than the second wavelength or half-wavelength of the joined second ring.

[0036] (19) The first wavelength or half-wavelength between two peaks of the ring is different from the second wavelength between the other two peaks of the same ring.

[0037] (20) The ring is sinusoidal or zigzag.

[0038] For a marker link having a maximum width that is approximately 200% greater than the maximum width of a non-marker link, the half-wavelength measured from the W peak formed between the marker link and the first ring is approximately 15% greater than the half-wavelength measured from the Y peak formed between the marker link and the second ring coupled to the first ring.

[0039] For a marker link having a maximum width that is approximately 200% greater than the maximum width of a non-marker link, the wavelength measured from the W peak formed between the marker link and the first ring is approximately 5% - 10% greater than the wavelength measured from the Y peak formed between the marker link and the second ring coupled to the first ring.

[0040] For a marker link having a maximum width that is approximately 200% greater than the maximum width of a non-marker link, the wavelength measured from the W peak / hill formed between the marker link and the ring is approximately 5% - 10% greater than the wavelength measured between other hills of the ring.

[0041] A top width B1 that is greater than the top width B2, for example, a top width B1 that is approximately 350% - 400% greater than the top width B2.

[0042] The inter-ring spacing A12 between the first ring and the second ring is greater than the inter-ring spacing A23 between the second ring and the third ring. For example, A12 is approximately 40% greater than A23.

[0043] The link is a straight link or a non-linear link. For example, link 20 and link 636.

[0044] A length c1 that is approximately 36% greater than the length c2 of the marker link.

[0045] A length c1 that is approximately 36% greater than the length c2 of the non-linear link.

[0046] (29) A medical device, a thin-walled scaffold having a network of a plurality of rings interconnected by links, each ring having a plurality of peaks, the peaks being one of a U top, a Y top, and a W top, each ring extending circumferentially in a wavy manner along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A), the thin-walled scaffold; a marker link extending between a first ring and a second ring of the plurality of rings, the marker link including a structure having a hole, the hole containing a radiopaque material, the marker link; and the marker link forms the W top of the first ring and the Y top of the second ring, and the half wavelength of the first ring measured from the W top of the first ring to the adjacent U top in the first ring is greater than the half wavelength of the second ring measured from the Y top of the second ring to the adjacent U top in the second ring.

[0047] (30) The medical device according to (29), combined with one or more of the following items (a) to (g), or any combination thereof. (a) The length of the marker link is greater than the length of the link connecting the second ring to a third ring coupled to the second ring. (b) The marker link includes a first link portion extending from the structure to the W top of the first ring and a second link portion extending from the Y top of the second ring to the structure, and the width of the first link portion is shorter than the length of the second link portion. (c) The length of the first link portion is smaller than the length of the second link portion. (d) The structure includes a first hole and a second hole each containing a radiopaque material, and the first hole and the second hole are arranged parallel to the axis A-A. (e) The first ring includes a first peak, a second peak, and a third peak, the first peak corresponding to the W top of the first ring, the second peak being adjacent to the first peak, the third peak being adjacent to the second peak, and the second wavelength extending from the second peak to the third peak is smaller than the first wavelength extending from the first peak to the second peak. (f) The flat portion of the W top of the first ring is larger than the flat portion of the W top of the third ring of the third ring coupled to the second ring and / or the flat portion of the fourth W top of the first ring. (g) The wavelength of the first ring forming the W top of the first ring is longer than the wavelength of the second ring forming the Y top of the second ring.

[0048] (31) A medical device, a thin-walled scaffold having a proximal end portion and a distal end portion formed by a network of a plurality of rings interconnected by links, each ring having a plurality of peaks, the peaks being one of a U top, a Y top and a W top, each ring extending circumferentially in a wavy shape along a vertical axis (B - B) perpendicular to the longitudinal axis (A - A), the thin-walled scaffold, and a marker link extending between a first ring and a second ring of the plurality of rings, the marker link including a structure having a hole, the hole containing a radiopaque material, the medical device comprising the marker link, the marker link forming the W top of the first ring and the first ring, forming the Y top of the second ring and the second ring, the W top of the first ring corresponding to the first peak, the first wavelength of the first ring measured from the first peak to the second peak of the first ring adjacent to the first peak being larger than the second wavelength of the first ring measured from the second peak to the third peak of the first ring adjacent to the first ring.

[0049] (32) The medical device according to (31), combined with one or more of the following items (a) to (c), or any combination thereof. (a) The first ring has n peaks and n - 1 wavelengths, n being at least 6 and at most 12, the first wavelength and the second wavelength being measured vertically from the first peak respectively, and the first peak being larger than the remaining n - 3 wavelengths measured between the n - 1 peaks. (b) All of the remaining n - 3 wavelengths have the same length. (c) The length of the marker link is approximately equal to the length of the link connecting the second ring to the third ring.

[0050] (33) A medical device comprising: a balloon catheter having a balloon with a distal balloon end and a proximal balloon end; a thin-walled scaffold crimped to the balloon and formed by a network of a plurality of rings interconnected by links, the thin-walled scaffold having a proximal end portion and a distal end portion, each ring having a plurality of peaks, the peaks being one of a U-top, a Y-top, and a W-top, each ring extending circumferentially in a wave shape along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A); a marker link extending between a first ring and a second ring of the plurality of rings, the marker link including a structure having a hole, the hole containing a radiopaque material, wherein the marker link forms the W-top of the first ring and the Y-top of the second ring, the W-top of the first ring corresponding to a first peak, a first wavelength of the first ring measured from the first peak to a second peak adjacent to the first peak being greater than a second wavelength of the first ring measured from the second peak to a third peak adjacent to the second peak, and the thin-walled scaffold having an outer diameter of about D-min, where D-min = (1 / π) × [(n × strut_width) + (m × link_width)] + 2 × t.

[0051] (34) The medical device according to (33), combined with one or more of the following items (a) to (d), or any combination thereof. (a) The maximum width of the structure measured along the axis B-B is greater than the maximum width of the link extending between the second ring and a third ring coupled to the second ring. (b) The marker link includes a first link portion extending from the structure to the W-top and a second link portion extending from the Y-top to the structure, the width of the first link portion being greater than the width of the second link portion. (c) The length of the first length portion is less than the length of the second link portion. (d) The structure includes a first hole and a second hole containing a radiopaque material, the first hole and the second hole being arranged parallel to the axis A-A.

[0052] (35) A method for manufacturing a medical device, comprising the steps of using a tube containing poly(L-lactide), and forming a thin-walled scaffold pattern from the tube, wherein the thin-walled scaffold is formed by a network of a plurality of rings interconnected by links, has a proximal end portion and a distal end portion, each ring has a plurality of peaks, the peaks are one of a U-top, a Y-top and a W-top, each ring extends circumferentially in a wavy manner along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A), the thin-walled scaffold includes at least one marker link extending between a first ring and a second ring coupled to the first ring of the plurality of rings, the marker link includes a structure having a hole, the step of forming the thin-walled scaffold pattern, the step of disposing a radiopaque material in the marker hole, the hole having a first size before material disposition and a second size larger than the first size after material disposition, the structure having a width measured along the axis B-B, the step of disposing the radiopaque material, and the step of crimping the thin-walled scaffold to a balloon catheter, wherein the thin-walled scaffold is crimped to approximately the theoretically minimum crimp diameter (D-min), and any peak adjacent to the top or bottom of the structure does not overlap with the structure.

[0053] (36) The medical device according to (35), combined with one or more of the following items (a) to (c), or any combination thereof. (a) The marker link forms a W-top of the first ring and the first ring, forms a Y-top of the second ring and the second ring, the W-top of the first ring corresponds to the first peak, and the first wavelength of the first ring measured from the first peak to the second peak adjacent to the first peak is larger than the second wavelength of the first ring measured from the second peak to the third peak adjacent to the second peak. (b) The marker link forms the first ring and the W top of the first ring, forms the second ring and the Y top of the second ring. The first U top and the second U top are respectively adjacent above and below the W top of the first ring. The first strut extends from the W top of the first ring to the first U top, and the second strut extends from the W top of the first ring to the second U top. The distance between the first U top and the second U top, or the distance from the second strut to the first strut, is greater than or equal to the maximum width of the marker structure measured along the axis B-B. (c) The width of the marker structure is greater than the maximum width of the link connecting the second ring to an adjacent third ring.

[0054] (37) A medical device, a thin-walled scaffold having a proximal end portion and a distal end portion, formed by a network of a plurality of rings interconnected by links of the thin-walled scaffold. Each ring has a plurality of tops including a U top and at least one of a Y top and a W top. Each ring extends circumferentially in a wavy shape along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A). The proximal end portion includes the outermost proximal ring coupled to the first proximal ring by a first proximal link. The first proximal ring is coupled to the second proximal ring by a second proximal link. The distal end portion includes the outermost distal ring coupled to the first distal ring by a first distal link. The first distal ring is coupled to the second distal ring by a second distal link. The first proximal link includes a proximal marker link having a proximal hole containing a radiopaque material. The first distal link lacks a link holding a radiopaque material.

[0055] (38) The medical device according to (37), combined with one or more of the following items (a) to (i), or any combination thereof. (a) The outermost proximal ring is coupled to the first proximal ring only by the first proximal link. Two of the first proximal links extend parallel to the axis A-A and have a constant cross-sectional second moment of inertia. (b) The outermost distal ring is coupled to the first distal ring only by the first distal links, and each of the first distal links is a non-linear link strut. (c) The proximal marker link has a first end and a second end, the first end forming the outermost proximal ring and one of the W top and Y top, and the other of the first proximal ring and the W top and Y top. (d) The first distal ring and the second distal ring are coupled by a distal marker link. (e) The distal marker link includes a structure surrounding two holes, and the first distal ring and the second distal ring are further coupled by one or more marker links. (f) The distal marker link has a first end and a second end, the first end forming the first distal ring and one of the W top and Y top, and the second distal ring and the other of the W top and Y top, and the W top is wider than the Y top. (g) The proximal marker link further comprises a periphery generally surrounding a hole and defining a hole wall and a strut periphery, the distance between the wall and the periphery being D, a radiopaque marker disposed in the hole and including a head having a flange disposed on the periphery, the flange having a radial length of 1 / 2D to less than D, and the thin-walled scaffold thickness (t) being related to the length (L) of the marker measured between the anti-luminal side and the luminal side of the marker by 1.1 ≦ (L / t) ≦ 1.8. (h) The distal marker link forms one of the W top and Y top of the first distal ring and the second distal ring, and the half wavelength of the ring having the W top, measured from the top adjacent to the first, is greater than the half wavelength of the ring having the Y top. (i) The length of the first proximal link is shorter than the length of the first distal link, and / or the length of the second distal link is smaller than the length of the first distal link.

[0056] (39) A medical device comprising a balloon catheter having a balloon with a distal balloon end and a proximal balloon end, and a thin-walled scaffold crimped to the balloon and formed by a network of a plurality of rings interconnected by links of the thin-walled scaffold, the thin-walled scaffold having a proximal end portion and a distal end portion, each ring having a plurality of tops including a U-top and at least one of a Y-top and a W-top, each ring extending circumferentially in a wavy manner along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A), the proximal end portion being crimped to the proximal balloon end and including the outermost proximal ring coupled to a first proximal ring by a first proximal link, the first proximal ring being coupled to a second proximal ring by a second proximal link, the distal end portion being crimped to the distal balloon end and including the outermost distal ring coupled to a first distal ring by a first distal link, the first distal ring being coupled to a second distal ring by a second distal link, the first proximal link including a proximal marker link having a proximal hole comprising a radiopaque material, the first distal link lacking a link for holding a radiopaque material, the first distal link comprising a non-linear link, the thin-walled scaffold having an outer diameter of about D-min, where D-min = (1 / π)×[(n×strut_width)+(m×link_width)]+2*t, the medical device.

[0057] (40) The medical device according to (39), combined with one or more of the following items (a) to (i), or any combination thereof. (a) The outermost proximal ring is coupled to the first proximal ring only by the first proximal link, and each of the first proximal links extends parallel to the axis A-A and has a constant cross-sectional second moment of inertia. (b) The non-linear link is a U-shaped link. (c) The proximal marker link has a first end and a second end. The first end forms the outermost proximal ring and one of the W-top and the Y-top, and the first proximal ring and the other of the W-top and the Y-top. The marker link includes a structure surrounding the hole. (d) The first link portion of the proximal marker link extends from the W-top to the structure, and the second link portion of the proximal marker link extends from the Y-top to the structure. The length of the first link portion is greater than the length of the second link portion. (e) The length of the first link portion is approximately equal to the sum of twice the ring width and the length of the strut extending between the U-top and the U-top, Y-top, or W-top of the ring. (f) The non-linear link has a first end and a second end. The first end forms the outermost proximal ring and one of the W-top and the Y-top, and the first proximal ring and the other of the W-top and the Y-top. The non-linear link includes a U-shaped structure between the W-top and the Y-top. (g) The first link portion of the proximal U-shaped link extends from the W-top to the U-shaped structure, and the second link portion of the proximal marker link extends from the Y-top to the structure. The length of the first link portion is greater than the length of the second link portion. (h) The length of the first link portion is approximately equal to the sum of twice the ring width and the length of the strut extending between the U-top and the U-top, Y-top, or W-top of the ring. (i) The distal marker link has a first end and a second end. The first end forms the first distal ring and one of the W-top and the Y-top, and the second distal ring and the other of the W-top and the Y-top.

[0058] (41) A medical device, a thin-walled scaffold having a proximal end portion and a distal end portion formed by a network of a plurality of rings interconnected by links of the thin-walled scaffold, each ring having a plurality of tops including a U-top and at least one of a Y-top and a W-top, each ring extending circumferentially in a wavy shape along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A), comprising a thin-walled scaffold, the proximal end portion including the outermost proximal ring coupled to the first proximal ring by a first proximal link, the first proximal ring being coupled to the second proximal ring by a second proximal link, the distal end portion including the outermost distal ring coupled to the first distal ring by a first distal link, the first distal ring being coupled to the second distal ring by a second distal link, the first proximal link including a proximal marker link having a pair of proximal holes containing a radiopaque material, the proximal holes being arranged along the axis A-A, the first distal link including a distal marker link having a pair of distal holes containing a radiopaque material, the distal holes being arranged along the axis B-B.

[0059] (42) The medical device according to (41), combined with one or more of the following items (a) to (i), or any combination thereof. (a) The outermost proximal ring is coupled to the first proximal ring only by the first proximal link, and two of the first proximal links extend parallel to the axis A-A and have a constant cross-sectional second moment of inertia. (b) The outermost distal ring is coupled to the first distal ring only by the first distal marker link and a non-linear link strut. (c) The proximal marker link has a first end and a second end, the first end forming one of the W-top and the Y-top with the outermost proximal ring and the other of the W-top and the Y-top with the first proximal ring. (d) The width of the W top formed by the first end is greater than the width of the Y top formed by the second end, so the wavelength of the ring forming the W top is longer than the wavelength of the ring forming the Y top. (e) The distal marker link has a first end and a second end. The first end forms one of the outermost distal rings and the W top and the Y top, and the first distal ring forms the other of the W top and the Y top. (f) The distal marker link includes a first link portion extending from the hole to the W top and a second link portion extending from the hole to the Y top, and the length of the first link portion is longer than the length of the second link portion. (g) The proximal marker link further includes a periphery that generally surrounds the hole and defines the hole wall and the strut periphery, where the distance between the wall and the periphery is D, and a radiopaque marker disposed in the hole and including a head having a flange disposed on the periphery. The flange has a radial length of 1 / 2D to less than D, and the thin-walled scaffold thickness (t) is related to the length (L) of the marker measured between the anti-luminal side and the luminal side of the marker by 1.1 ≦ (L / t) ≦ 1.8. (h) The radiopaque material is contained within the hole, and the radiopaque material has a frustum shape. (i) The hole includes a first opening and a second opening respectively located on the first side and the second side of the marker link. The first opening is larger than the second opening, and the frustum is substantially in the same plane as the first opening and the second opening.

[0060] (43) A medical device comprising: a balloon catheter having a balloon with a distal balloon end and a proximal balloon end; a thin-walled scaffold crimped to the balloon and formed by a network of a plurality of rings interconnected by links of the thin-walled scaffold, the thin-walled scaffold having a proximal end portion and a distal end portion, each ring having a plurality of tops including a U-top and at least one of a Y-top and a W-top, each ring extending circumferentially in a wavy pattern along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A); wherein the proximal end portion is crimped to the proximal balloon end and includes an outermost proximal ring coupled to a first proximal ring by a first proximal link, the first proximal ring being coupled to a second proximal ring by a second proximal link, the distal end portion being crimped to the distal balloon end and including an outermost distal ring coupled to a first distal ring by a first distal link, the first distal ring being coupled to a second distal ring by a second distal link; (1) the first proximal link includes a proximal marker link having a structure that extends parallel to axis A-A and includes a radiopaque material; (2) the first distal link includes a distal marker link having a structure that extends parallel to axis B-B and includes a radiopaque material; the thin-walled scaffold having an outer diameter of about D-min, where D-min = (1 / π)×[(n×strut_width)+(m×link_width)]+2*t. A medical device.

[0061] (44) The medical device according to (43), combined with one or more of the following items (a) to (i), or any combination thereof. (a) The outermost proximal ring is coupled to the first proximal ring only by the first proximal link, and each of the first proximal links extends parallel to axis A-A and has a constant cross-sectional second moment of inertia. (b) The first distal link includes a non-linear link. (c) The proximal marker link has a first end and a second end. The first end forms one of the outermost proximal ring and the W top and the Y top, and the first proximal ring and the other of the W top and the Y top. The marker link includes a structure surrounding the hole. (d) The first link portion of the proximal marker link extends from the W top to the structure, and the second link portion of the proximal marker link extends from the Y top to the structure. The length of the first link portion is greater than the length of the second link portion. (e) The length of the first link portion is approximately equal to the sum of twice the ring width and the length of the strut extending between the U top and the Y top, U top or W top of the ring. (f) The first distal link includes a non-linear link having a first end and a second end. The first end forms one of the outermost proximal ring and the W top and the Y top, and the first proximal ring and the other of the W top and the Y top. The non-linear link includes a U-shaped structure between the W top and the Y top. (g) The first link portion of the non-linear link extends from the W top to the U-shaped structure, and the second link portion of the non-linear link extends from the Y top to the U-shaped structure. The length of the first link portion is greater than the length of the second link portion. (h) The length of the first link portion is approximately equal to the sum of twice the ring width and the length of the strut extending between the U top and the Y top, U top or W top of the ring. (i) The hole of the distal marker link is between the U top adjacent to the W top of the outermost distal ring and the U top adjacent to the Y top of the first distal ring, and does not overlap or underlap with these.

[0062] [Incorporation by reference]

[0018] All documents and patent applications described in this specification are incorporated herein by reference as if each individual document or patent application was specifically and individually indicated to be incorporated by reference. To the extent there are conflicting usages of terms between the incorporated document or patent and this specification, those terms have the meaning that is consistent with the usage in which they are used in this specification.

Brief Description of the Drawings

[0063]

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Best Mode for Carrying Out the Invention

[0064]

[0056] In this specification, similar reference numerals described in the drawings and the specification designate corresponding elements or similar elements in different drawings.

[0065]

[0057] The following terms and definitions apply to the present disclosure.

[0066]

[0058] The terms "about", "approximately", "generally", or "substantially" mean that the recited value, range, or each endpoint of the recited range is 30%, 20%, 15%, 10%, 5%, 4%, 3%, 2%, 1.5%, 1%, 1 - 2%, 1 - 3%, 1 - 5%, or 0.5 - 5% less than or more than, less than, or more than the recited value, or is within 1 sigma, 2 sigma, 3 sigma of the recited average or expected value (Gaussian distribution). For example, d1 is about d2 means that d1 differs from d2 by 30%, 20%, 15%, 10%, 5%, 4%, 3%, 2%, 1.5%, 1%, 0% or 1 - 2%, 1 - 3%, 1 - 5%, or 0.5 - 5%. When d1 is the average value, d2 is about d1 means that d2 is within 1 sigma, 2 sigma, or 3 sigma of the variance or standard deviation from d1.

[0067]

[0059] It should be understood that any numerical value, range, or range endpoint (including, for example, "about nothing", "almost nothing", "almost all", etc.) preceded by the words "about", "approximately", "generally", or "substantially" in this disclosure also describes or discloses the same numerical value, range, or range endpoint without the words "about", "approximately", "generally", or "substantially" preceding it.

[0068]

[0060] The "glass transition temperature", TG, is the temperature at which the amorphous domain of a polymer changes from a brittle glassy state to a deformable or ductile state of a solid at atmospheric pressure. In this application, the method for finding the TG of a polymer, or TG - low (the lower limit of the TG range), is defined in the same way as in the specification of US Patent Application No. 14 / 857635 (Docket No.: 62571.1216).

[0069] As used herein, the term "stent" generally refers to a permanent, durable, or non-degradable structure made of a non-degradable metal or alloy structure. On the other hand, the term "scaffold" includes a bioabsorbable or biodegradable polymer, metal, alloy, or combinations thereof, and refers to a temporary structure that can radially support a blood vessel for a limited period, such as 3 months, 6 months, or 12 months after implantation. However, in the art, it should be understood that the term "stent" is often used to refer to either type of structure.

[0070]

[0062] The "expansion diameter" or "dilation diameter" refers to the inner or outer diameter that the scaffold obtains when its support balloon inflates the scaffold from its crimped form for implanting the scaffold into a blood vessel. The expansion diameter may refer to the post-expansion balloon diameter that exceeds the nominal balloon diameter. For example, the post-expansion diameter of a 6.5 mm balloon (i.e., a balloon having a nominal diameter of 6.5 mm when inflated to a nominal balloon pressure such as 6 times atmospheric pressure) is about 7.4 mm, and the post-expansion diameter of a 6.0 mm balloon is about 6.5 mm. The ratio of the nominal to post-expansion of the balloon can be in the range of 1.05 to 1.15 (i.e., the post-expansion diameter may be 5% to 15% larger than the nominal inflated balloon diameter). The scaffold diameter decreases to some extent due to a rebound effect mainly related to any or all of the method by which the scaffold is manufactured and processed, the material of the scaffold, and the design of the scaffold, after obtaining the expansion diameter by balloon pressure.

[0071]

[0063] Unless otherwise specified or indicated by the context of the description, the term "diameter" shall mean the inner or outer diameter.

[0072]

[0064] The term "scaffold strut" also applies to links and bar arms.

[0073]

[0065] The "post-deployment diameter" (PDD) of a scaffold refers to the inner diameter of the scaffold after it has been increased to its deployed diameter and the balloon has been removed from the patient's vasculature. PDD takes into account the recoil effect. For example, acute PDD refers to the scaffold diameter considering acute recoil in the scaffold.

[0074]

[0066] The "pre-crimp diameter" means the outer diameter (OD) of the scaffold before it is crimped onto a tube (e.g., cut from a tube that has been subjected to dip coating, injection molding, extrusion, radial expansion, die stretching, and / or annealing) or balloon, which is the material from which the scaffold is made. Similarly, the "crimp diameter" means the OD of the scaffold when it is crimped onto the balloon. The "pre-crimp diameter" can be about 2 to 2.5 times, 2 to 2.3 times, 2.3 times, 2 times, 2.5 times, 3.0 times the size of the crimp diameter, the deployed diameter, the nominal balloon diameter, or about 0.9 times, 1.0 times, 1.1 times, 1.3 times, and about 1 to 1.5 times the size of the post-deployment diameter. Crimping, as used in this disclosure, means a reduction in the diameter of the scaffold characterized by significant plastic deformation, i.e., a diameter reduction of more than 10% or more than 50% can be attributed to plastic deformation, such as at the apex in the case of a stent or scaffold having a wavy ring pattern, as shown, for example, in FIG. 1. When the scaffold is deployed or expanded by a balloon, the inflated balloon plastically deforms the scaffold from its crimp diameter. A method for crimping a scaffold made in accordance with this disclosure is described in the specification of U.S. Patent Application No. 2013 / 0255853 (Docket No. 62571.628).

[0075] A material “comprising” or “comprises” poly(L-lactide) or PLLA includes, but is not limited to, a PLLA polymer, a blend or mixture comprising PLLA and another polymer, and a copolymer of PLLA and another polymer. Thus, a strut comprising PLLA means that the strut can be made of a material that includes any one of a PLLA polymer, a blend or mixture comprising PLLA and another polymer, and a copolymer of PLLA and another polymer.

[0076]

[0068] A bioabsorbable scaffold made of a biodegradable polyester polymer is radiopaque. To enable fluoroscopy, a radiopaque marker is placed on the scaffold. For example, the scaffold described in U.S. Patent No. 8,388,673 ('673 patent) has two platinum markers 206 fixed to each end of the scaffold 200, as shown in FIG. 2 of the '673 patent.

[0077]

[0069] When referring to a direction perpendicular to axis A-A (e.g., as shown in FIG. 3) or parallel to axis A-A and / , it means perpendicular to the axial direction of the scaffold or tube, or parallel to the axial direction and / thereof. Similarly, when referring to a direction perpendicular to axis B-B (e.g., as shown in FIG. 3) or parallel to axis B-B and / , it means perpendicular to the circumferential direction of the scaffold or tube, or parallel to the circumferential direction and / thereof. Thus, the sinusoidal ring of the scaffold extends (periodically) parallel to the circumferential direction and / or parallel to axis B-B and perpendicular to axis A-A, while the other link, in one embodiment, extends parallel to the axial direction of the scaffold or tube or axis A-A and perpendicular to axis B-B.

[0078]

[0070] It should be understood that whenever the same element number is used in multiple drawings, unless otherwise stated, the description originally used for the element in the first drawing applies to the embodiments described in subsequent drawings.

[0079]

[0071] The thickness dimension (e.g., the thickness of a wall, strut, ring or link) refers to the dimension measured perpendicular to both axis A-A and axis B-B. The width dimension is measured within the plane of axis A-A and axis B-B. More specifically, the width is the cross-sectional width from one side to the other side of a continuous structure. Thus, the U-shaped link 636 has a constant link width over its length, just as the link 334 has a constant link width. Further, it should be understood that the so-called plane of axis A-A and axis B-B describes the surface of a tubular structure having a central lumen axis parallel to axis A-A and is not technically a plane. Thus, axis B-B may alternatively be considered as the angular component in the case where the scaffold position is described using a cylindrical coordinate system (i.e., axis A-A is the Z-axis and the positions of the lumen side / anti-lumen side of the top, link, ring, etc. are found by angular and radial coordinate constants).

[0080]

[0072] "Thin-walled", "thin-walled scaffold", "thin-wall" refer to struts, rings, links, or bar arms made of a polymer containing poly(L-lactide) and having a wall thickness of less than 125 microns (μm). This specification discusses the challenges faced when dealing with thin-walled scaffolds, including holding markers having the same volume of radiopaque material.

[0081]

[0073] FIG. 2 is a top view of a portion of a polymer scaffold, for example, a polymer scaffold having a pattern of rings interconnected by links. A marker link 20 ("link 20") extends between rings 312a, 312b of FIG. 2. Link 20 forms left and right structures or strut portions 21b, 21a, respectively, for holding a radiopaque marker. The marker can be held in a hole 22 formed by structures 21a, 21b. Surface 22a corresponds to the anti-luminal side surface of the scaffold.

[0082]

[0074] FIG. 2A is a copy of FIG. 2 showing additional dimensional features, particularly characteristic dimensional features D0, D1, and D2. The diameter of hole 22 is D0. The distance between adjacent holes 22 is D1 or more. The width of the edge of either or both of holes 22, that is, the distance from the inner wall surface surrounding either or both of holes 22 to the edge of link 20 is D2 or more.

[0083]

[0075] FIG. 2B shows the dimensional features described in relation to FIG. 2A for a marker link 720 in which structures 21a, 21b are oriented so as to be offset along axis B - B rather than axis A - A. Marker 720 connects ring 312a and ring 312b. The scaffold embodying this marker is shown in FIG. 7.

[0084]

[0076] Figure 2C shows a rivet - type marker 127’ / 137’ fixed to hole 22. The dimensions indicated are parameters that can be used to inspect the marker link (after the radiopaque material is connected) to evaluate the ability of the marker link to resist the forces that tend to cause the rivet 127’ / 137’ to fall out of hole 22. These dropout forces can be caused by the deformation of the pressurized balloon surface or the nearby scaffold structure that tends to deform hole 22 when the scaffold is crimped or balloon - expanded. According to one aspect, the rivet heads and / or the tip portions of the pair of rivets 127’ / 137’ can be inspected to determine whether the minimum distances δ1, δ2, and δ3 (Figure 2C) are satisfied. The distances δ1, δ2, and δ3 reflect either or both of the minimum sizes of the head and / or tip of the rivet pushed into the hole, and this size indicates both that the rivet should be held within hole 22 (if the diameter of the head or tip is too small, it cannot resist the dropout force) and that excessive rivet material should not cause problems such as balloon puncture or blood vessel irritation when the scaffold is implanted into the blood vessel. According to an embodiment, the minimum distance from the end of the head / tip of the marker to the edge of the strut (or link) portion 21a / 21b, i.e., δ2, can be about 10%, 25%, and up to 50% of D2. Above 50% means that the head or tip is too small to hold the rivet in place. For a head / tip larger than D2, the head may extend beyond the edge of the strut / link or extend, which may lead to problems such as forming a relatively sharp edge that can damage the balloon or irritate adjacent tissue. The minimum distance between the marker heads / tips, i.e., δ1, is 0% or up to 25% of the distance D1. If the peripheries or heads of the markers overlap each other, this may exceed the maximum height required for the strut (about 160 microns (μm)). The minimum length of the head / tip extending to the right or left of hole 22, i.e., δ3, is greater than 50% of D2.

[0085]

[0077] Methods for inserting a radiopaque marker into a hole generally utilize a cylindrical hole to hold the marker. Most of the holding force is due to friction between the wall and the marker material. The marker material is securely held in the scaffold hole by this method when the scaffold has a wall thickness of 150 microns (μm) or more. However, when the wall thickness is reduced to 100 microns (μm) or less, it becomes much more difficult to hold the marker material within the hole. A coating material for carrying drugs may also help hold the marker in place, but coatings such as everolimus / PDLLA are on the order of 3 microns (μm) and tend to be very thin, thus limiting the out-of-plane shear strength that resists marker dropout from the hole.

[0086]

[0078] There are several desirable properties or capabilities that result from reducing the wall thickness of the scaffold struts. Advantages of using a reduced wall thickness include being of a lower profile, thus having better introducibility, reduced acute thrombogenicity, and the potential for improved healing. In some embodiments, it is desirable to use the same size marker on a scaffold with thinner struts so that there is no difference, i.e., reduction, in radiopacity between the two types of scaffolds. However, reducing the strut thickness while keeping the marker hole 22 the same size can result in the marker protruding above and / or below the strut surface due to the reduced hole volume. It is desirable to keep the marker's anti-luminal side 25a and luminal side 25b coplanar with the corresponding anti-luminal and luminal sides of the strut, in which case the hole 22 diameter (d) can be increased to partially compensate for the reduced hole volume resulting from the thinner struts.

[0087] [

[0079] ] Paragraphs

[0073] to

[0083] of US Patent Application No. 14 / 738,710, which is common to the present application and the inventors, describe factors that affect the ability of a scaffold to hold a marker in a hole, and the special challenges faced when the wall thickness is less than 160 microns (μm) or less than 125 microns (μm). According to some embodiments, when the wall thickness is less than 125 microns (μm), that is, when the scaffold is thin-walled, it has been found that the marker cannot be reliably held in the hole solely by friction. In a preferred embodiment where the wall thickness is less than 100 microns (μm), the marker material is held in the hole using a rivet-shaped marker that was briefly described above in connection with Figure 2C and will be described in more detail in connection with Figures 8 to 16.

[0088] [

[0080] ] Hereinafter, embodiments of a scaffold pattern suitable for fulfilling one or a combination of the following objectives will be described. (i) Thinning the crimp profile of a thin-walled scaffold that supports a radiopaque marker. (ii) Fixing a radiopaque marker within a thin-walled scaffold. (iii) Reducing strain energy accumulation in the marker retention structure when the thin-walled scaffold is deformed during crimping, balloon dilation at the target vessel site, or introduction of the scaffold into the target site. (iv) Avoiding the protrusion or flare ring at the distal end of the scaffold for a thin-walled scaffold or a scaffold that includes PLLA and has a wall thickness greater than 125 microns (μm).

[0089]

[0081] The above objectives are interrelated, and it will be understood that a single change can address multiple objectives. For example, by making the marker link more flexible, both objective (iii) and objective (iv) can be satisfied. The scaffolds according to these embodiments may be made from a thin-walled tube or sheet of a material comprising poly(L-lactide) (PLLA), and such thin-walled tubes or sheets are laser cut from the tubular body to produce the patterns shown in FIGS. 3-7. The method of making the tube may include one or more of extrusion, injection molding, solid-phase processing, and biaxial stretching as described in the specification of U.S. Patent Application No. 14 / 810,344 (62571.1212).

[0090]

[0082] The scaffolds according to the embodiments, such as scaffolds 300, 400, 500, 600 or 700, are preferably crimped to a balloon catheter as shown in FIG. 3D. The scaffold may be attached to the balloon to ensure a desired crimp diameter, such as D-min (defined below), using any of the crimping methods described in the specification of U.S. Patent Application No. 2013 / 0255853, specifically, paragraphs

[0068] -

[0073] ,

[0077] -

[0099] ,

[0111] -

[0126] ,

[0131] -

[0146] of U.S. Patent Application No. 2013 / 0255853 and the crimping methods and apparatuses for crimping described in FIGS. 1A, 1B, 4A, 4B, 5A, 5B, 8A and 8B.

[0091]

[0083] Figure 3 shows a partial plan view of the end portion of a scaffold according to an embodiment, i.e., scaffold 300. The left or distal end portion 302 (i.e., the left side in FIG. 3) includes sinusoidal rings 312a, 312b, and 312c, with ring 312a being the outermost ring. Ring 312a and ring 312b are coupled by two links 334 and marker link 20. Ring 312c and ring 312d are coupled by three links 334 that extend parallel to axis A-A. The links 334 extend parallel to axis A-A and have a constant cross-sectional second moment over their length, which means that the links 334 have a constant width and thickness, and the position of the centroid or geometric center (or longitudinal axis) of the link is parallel to axis A-A anywhere. The right or proximal end portion 304 (i.e., the right side in FIG. 3) includes sinusoidal rings 312d, 312e, and 312f, with ring 312f being the outermost ring. Ring 312d and ring 312e are coupled by three links 334. Ring 312e and ring 312f are coupled by two links 334 and marker link 20. Thus, the scaffold 300 has a marker link 20 that extends between the outermost link and the adjacent inner ring and couples the outermost link to the adjacent inner ring. The scaffold 300 may have 15, 18, or 20 rings 312 interconnected by links 334.

[0092]

[0084] The ring 312, such as ring 312b, is sinusoidal, which means that the curvature of the ring along axis B-B is best explained by a sine wave where the wavelength of the sine wave is equal to the distance between adjacent peaks 311a of the ring. The ring has a constant width in both the tops 307, 309, 310 and the struts 330 that connect adjacent tops.

[0093]

[0085] Each of the inner rings 312b to 312e has three types of tops: a U-top, a Y-top, and a W-top. The outermost ring has only the Y-top type or the W-top type and the U-top type. The ridge or peak 311a (or the valley or trough 311b) may correspond to a U-top, a Y-top, or a W-top. The outermost ring 312a has only the U-top type and the W-top type. The outermost ring 312f has only the U-top type and the Y-top type. The marker link 20 joins the rings by forming a W-top with a first ring (e.g., ring 312e) and a Y-top with a second ring (e.g., ring 312f).

[0094]

[0086] The link 334 is connected to the ring 312f at the Y-top 310. The "Y-top" refers to a top where the angle extending between the strut 330 of the ring 312 and the link 334 is an obtuse angle (greater than 90 degrees). The link 334 is connected to the ring 312a at the W-top 309. The "W-top" refers to a top where the angle extending between the strut 330 and the link 334 is an acute angle (less than 90 degrees). The U-top 307 is a top to which no link is connected. The marker link 20 connects to the ring at the W-top 314 and the Y-top 316.

[0095]

[0087] In the scaffold 300, each ring 312 has six ridges or peaks 311a and six valleys or troughs 311b. A valley 311b always follows a ridge 311a. The ring 312b has twelve tops, three of which are W-tops 309, three of which are Y-tops 310, and six of which are U-tops 307.

[0096]

[0088] Figures 3A and 3B show partial enlarged views of the scaffold 300. Figure 3A shows section IIIA of Figure 3, and Figure 3B shows section IIIB of Figure 3. The following description is made with reference to Figures 3A to 3B, and in the case of the link 20, it is also applicable to the portions 302 and 304 of the scaffold 300 on the understanding that it is connected to the outermost ring 312f at the Y-top 316 and to the adjacent ring 312e at the W-top 314.

[0097]

[0089] Referring to FIG. 3A, the successive wavelengths of the outermost ring 312a have lengths L1 and L2, that is, the distance (along axis B-B) from the top 314 to the U top 307 is L1, and the distance from the U top 307 to the Y top 309 is L2. The same distances also apply to ring 312b, that is, the distance from the top 316 to the W top 309 and the distance from the W top 309 to the Y top 310 are L1 and L2 respectively. In the scaffold 300, for rings 312a and 312b, L1 = L2 = constant. That is, the distance or wavelength from one peak to another peak is the same. Also, in the scaffold 300, L1 + L2 is also constant everywhere. That is, for all rings, the distance between the W top and the Y top is the same as the distance between adjacent peaks of rings 312a to 312f. The distance X in FIG. 3A refers to the half period or half length of the sine wave, that is, 1 / 2 of L1. The distance X is equal to the distance from the top 314 to the U top 307 of the adjacent top 312a. X is the same for ring 312b. In other embodiments, L1 is not equal to L2, and X is different between the outermost ring 312a and the adjacent ring 312b.

[0098]

[0090] In alternative embodiments including the scaffold 400, scaffold 500 or scaffold 700 described below, the rings can be zigzag-shaped instead of sinusoidal-ring-shaped. An example of a zigzag-shaped ring is described in FIGS. 5A and 6A of U.S. Patent Application Publication No. 2014 / 0039604. The zigzag-shaped ring can be described as a non-curved strut element concentrated on the top formed to have an inner top radius and an outer top radius. The same description applies, that is, the ring can be described from the viewpoints of wavelength, strut and top, except that the shape is zigzag-shaped instead of sinusoidal. The term "wavy" refers to both the zigzag-ring type and the sinusoidal-ring type.

[0099] Referring to FIG. 3B, the distance along axis A-A from the peak or crest of ring 312a to the peak or crest of the adjacent ring 312b, i.e., the length of marker 20 (plus width t1) is A12. The distance along axis A-A from the peak or crest of ring 312b to the peak or crest of the adjacent ring 312c, i.e., the length of marker 334 between these rings (plus width t2) is A23. In the scaffold 300, A12 = A23. The width of link 20 on the left side of marker structure 21a is tm1, and the width of marker link 20 on the right side of structure 21b is tm2. The width of link 334 is tl1. The tops 307, 310, 309, 314 of ring 312a and strut 330 have a constant width t1. The tops 307, 310, 309, 314 of ring 312b and strut 330 have a constant width t2. The tops 307, 310, 309, 314 of ring 312c and strut 330 have a constant width t3. In the scaffold 300, t1 is less than t2, and t2 = t3. Dimensions B1 and B2 are the surfaces of the tops of rings 312a and 312c that extend parallel to axis B-B, or the flat top surface portions without curvature. In the scaffold 300, B1 = B2.

[0100] Referring to FIG. 3C, a scaffold 300 having a crimped marker 20 is shown. The crimp diameter implemented on the scaffold 300 is the theoretically minimum crimp diameter at which the struts that converge on the same top contact each other when the scaffold is fully crimped, i.e., when the scaffold is removed from the crimping device or placed in the restraint sheath immediately after crimping. The formula for the theoretically minimum crimp diameter (D-min) under these conditions is shown below. D-min=(1 / π)×[(n×strut_width)+(m×link_width)]+2*t wherein, "n" is the number of struts in the ring (12 struts in the scaffold 300), "strut_width" is the width of the strut (170 microns (μm) in the scaffold 300), "m" is the number of links connecting adjacent rings (3 in the scaffold 300), "link_width" is the width of the link (127 microns (μm) in the scaffold 300), "t" is the wall thickness (93 microns (μm) in the scaffold 300).

[0101]

[0093] Therefore, in the scaffold 300, D-min = (1 / π) × [(12 × 170) + (3 × 127)] + 2 × (93) = 957 microns (μm).

[0102]

[0094] In the coupled ring pairs 312a, 312b at the distal end 302 and the coupled ring pairs 312e, 312f at the distal end, the marker link 20 is wider (along the axis B-B) than the link 334 to accommodate the marker. As a result, the adjacent struts 330 will often overlap with the link 20 to achieve the same D-min throughout. This state is shown in Figure 3C. Such a state of the crimped scaffold raises concerns about the local strength of the rings and links holding the marker. As shown in Figure 3C, there is an overlap (the strut presses on the anti-luminal side of the marker) or underlap (the strut presses on the luminal surface of the marker) by the struts 330a, 330b and / or the associated U-tops associated with these struts. It is preferred to eliminate this overlap / underlap when the scaffold is crimped.

[0103]

[0095] The scaffold struts, particularly the struts and links of a thin-walled scaffold, are not designed to twist or support large twists. Twisting occurs when the struts contact and overlap each other. When the aspect ratio of the width to thickness of the scaffold struts is higher, the struts tend to twist more when contacting an adjacent structure, such as structure 21a of marker link 20 (a thin-walled scaffold has a higher aspect ratio and strut width for the same vascular tissue coverage compared to a thicker-walled scaffold). As can be understood from the deformed state of FIG. 3C compared to FIG. 3, twist is introduced into the ring structure and, in some cases, also into the marker link struts. This type of abnormal deformation may lead to crack propagation or a decrease in the fatigue life of the ring and / or link 20 during balloon dilation within a blood vessel.

[0104]

[0096] FIG. 3D shows a medical device comprising a balloon catheter and a scaffold 300 crimped to the balloon 15. The distal end 302 of the scaffold 300 is closest to the distal end 17b of the balloon 15, and the proximal end 304 is closest to the balloon proximal end 17a. The tip or most distal end 12 of the balloon catheter is shown. A guide wire or mandrel 8 extends from the tip 12 and exits from the lumen of the catheter shaft 2. The scaffold crimped to the balloon (according to D-min or other minimum crimp diameter) can be the scaffold 300 or scaffold 400 discussed below. Scaffold 500, scaffold 600, and scaffold 700 may be used instead of scaffold 300.

[0105]

[0097] As described above, when compared with scaffolds having a relatively thick wall thickness such as the scaffold described in US Patent Application Publication No. 2010 / 0004735 or the ABSORB GT1 bioabsorbable scaffold, thin-walled scaffolds having a similar scaffold pattern have been found to exhibit a significantly higher incidence of strut overlap or underlap (hereinafter referred to as MBOL), as shown in FIG. 3C. The MBOL incidence is likely to be high when the width of the link containing the marker is widened to accommodate the same total volume of marker material as used in scaffolds with thicker struts. MBOL can also be high when more aggressive crimping is used, for example, in the case of a D-min crimp profile.

[0106]

[0098] Furthermore, when the same volume of marker beads is attached to both thin-walled and thick-walled scaffolds and the markers are flush with the outer lumen side and the lumen side of the link, a flatter and wider shape must be used for the marker bead region, and this forced shape deforms structures 21a and 21b, increasing the tendency of strut overlap in the marker bead region. This is because the marker structure becomes more likely to have a higher aspect ratio to accommodate the marker and / or there may be residual strain from the marker implantation process, making the marker structure 21 more susceptible to out-of-plane torsion. These findings are summarized in Table 1.

Table 1

[0107]

[0099] In paragraphs

[0073] to

[0083] of U.S. Patent Application No. 14 / 738,710, which is common to this application and the inventor, factors affecting the ability of the scaffold to hold the marker and special problems faced when the wall thickness is less than 160 microns (μm) or less than 125 microns (μm) are described. In addition, in the '710 application, when the marker remains coplanar with the anti-luminal side of the strut as needed (thus having a higher aspect ratio and a higher tendency to twist and overlap during crimping), it also explains how much the width of the marker holding structure must be widened with the same volume of radiopaque material as the reduced wall thickness. When the marker structure is wider and flatter, the aspect ratio (AR) of the link width to wall thickness increases, which increases the likelihood of twisting when the link contacts an adjacent strut or top.

[0108]

[0100] In one example, the aspect ratio (AR) of the marker link of a thin-walled scaffold having a wall thickness of 93 microns (μm) is approximately 4.5 (AR = ts / t = 419 microns (μm) / 93 microns (μm) = 4.5) when the same volume of marker material is held by both the 93-micron marker structure and the 158-micron marker structure, as compared to the AR of a scaffold having a larger wall thickness of 158 microns (μm) as described in, for example, U.S. Patent Application No. 2010 / 0004735. For all scaffolds with a thickness of 158 microns (μm), the AR is approximately 2 (AR = ts / t = 322 / 158). Thus, when the wall thickness is reduced from 158 microns (μm) to 93 microns (μm) with the same volume of marker material, the AR increases by 2.5 times. Considering this significant increase in aspect ratio, it can be understood that the tendency for the marker link to twist when the marker link contacts an adjacent strut or top during crimping and / or the tendency for the strut to overlap / underlap with the marker link.

[0109]

[0101] During crimping, it is known that the angle of the bar arm of the scaffold decreases, and the adjacent bar arm strut naturally moves towards the link at the w-top. In this crimping event, the "outer radius" at the w-top and its center point (usually located outside the link) play an important role in guiding the way the scaffold strut crimps. In fact, the center point of this outer radius tends to act as a pivot point that guides the initial behavior of the strut and limits the extent of the strut movement towards the marker link mechanism. In this second aspect, the MBOL that occurs between the strut and the marker link mechanism is closely related to the position of this outer radius and the pivot point. In the case of the w-top with the marker link 20 and the thin-walled scaffold design, the center point of the w-top was initially positioned within the marker structure 21 region. Therefore, during crimping, the closing behavior of the strut is not kinematically restricted, and as a result, overlap / underlap with the marker link frequently occurs. In order to reduce the MBOL occurrence rate, the center point of the W-top with the marker structure 21 can be moved to a region outside the marker structure 21. Therefore, when the strut of the w-top moves towards the marker structure 21 during crimping, the strut should avoid entering an overlap or underlap state that is pushed, slides, and induces twisting of the w-top and / or the link.

[0110]

[0102] Figure 4 shows a partial plan view of the end portion of another embodiment of the scaffold, namely scaffold 400. The left or distal end portion 402 (i.e., the left side of FIG. 4) includes sinusoidal rings 412a, 312b, and 312c, with ring 412a being the outermost ring. Ring 412b and ring 312c are coupled by two links 334 and marker link 20. Ring 312c and ring 312d are coupled by three links 334 extending parallel to axis A-A. The right or proximal end portion 404 (i.e., the right side of FIG. 4) includes sinusoidal rings 312d, 412b, and 312f, with ring 312f being the outermost ring. Ring 312d and ring 412b are coupled by three links 334. Ring 412b and ring 312f are coupled by two links 334 and marker link 20. Thus, scaffold 400 has a marker link 20 that extends between the outermost link and the adjacent ring and couples the outermost ring to the adjacent ring. Scaffold 400 may have 15, 18, or 20 rings 312 interconnected by links 334.

[0111]

[0103] Scaffold 400 has the same features as described above for scaffold 300, except as follows. Rings 412a and 412b are sinusoidal and are coupled to the adjacent rings by W tops 414 and Y tops 416 (similar to the case of rings 312a and 312e), but the ring structures of rings 412a and 412b near marker 20 are modified to avoid strut overlap when the scaffold is crimped to the minimum theoretical crimp diameter (D-min) as described above.

[0112] Referring to FIGS. 4A and 4C, enlarged views of the scaffold 400 in section IVA and section IVB of FIG. 4 are shown respectively. To avoid the overlap described above, the spacing between the strut portions at the w-top of the markers between the ring 412a and the ring 412b has been increased. This change is shown at the w-top 414 in the drawing. The extended top (along axis B-B) provides more spacing between the strut 430 and the marker structures 21a, 21b to avoid overlap (the resulting crimp shape with this change is shown in FIG. 4D). The w-top 414 changes the scaffold structure near the marker 20 in at least one of the following (1), (2), and (3) ways, as opposed to the top 309 not associated with the marker link 20. (1) The flat, i.e., non-curved, surface portion B1 of the top increases in the direction of B-B above the flat surface portion B2 of the other w-tops 309, which is an increase of about 350% to about 400% relative to the maximum width (ts) of the marker link that is about 200% larger than the non-marker link width (tL), for example. (2) The distance from the w-top 414 (peak) to the adjacent u-top 407 (valley) increases compared to the distance from the y-top 316 (peak) of the ring 312b to the adjacent u-top 307 (valley), and / or the distance from any of the w-top 309 (peak) or y-top 310 (peak) of the ring 312 to the adjacent u-top 307 (valley). This is shown in the figure by comparing the distance X412 and the distance X312, which measure the length from the peak center to the valley center of the ring 412 and the ring 312 respectively. The distance X412 is about 15% larger than X312 of the marker link maximum width (ts) that is about 200% larger than the non-marker link width (tL). (3) The distance from mountain 414 to the adjacent mountain 407 is greater than the distance from mountain 407 to mountain 409, that is, L1 is longer than L2 in FIG. 4A. For example, L1 is about 10% longer than L2, and / or L1 is about 5% longer than the distance between any adjacent mountain of rings 312a, 312b, 312d, 312f and any adjacent mountain with a maximum marker link width (ts) that is about 200% greater than the non-marker link width (tL).

[0113]

[0105] The characteristics of ring 412a equally apply to ring 412b within the vicinity of marker link 20. FIG. 4B shows a view of the portion 302 where ring 412a is indicated by a dotted line from the scaffold 300 onto ring 312a. The added spacing between marker link 20 and strut 430 is represented by the "increase in spacing" in the drawing. In this drawing, the difference in the half-periods of the sinusoidal ring portions (X412, X312) extending respectively between the y-top and the w-top of the marker link can also be confirmed. Also, the characteristics of ring 412a are symmetric with respect to the w-top 414. Therefore, at least one of the modifications (1), (2), and (3) described above applies to both sides of the w-top 414.

[0114]

[0106] According to another aspect of the scaffold 400 related to the "increase in spacing" shown for the scaffold 400 to avoid MBOL or overlap, in some embodiments where the scaffold marker links are made to avoid overlap and the rings are connected, it is also beneficial to take into account the deformation of the structures 21a, 21b when marker elements, rivets, or beads are installed in the holes.

[0115] [

[0107] ]FIG. 4D shows a portion of the crimped scaffold 400 in a crimped state where the scaffold is crimped to D-min. As shown in the figure, the additional spacing between the strut portions 430a, 430b of the w-top 414 in the marker link 20 results in no overlap or underlap when the scaffold is crimped to the theoretically minimum crimp diameter, D-min. Specifically, in FIG. 4D, by modifying the ring 412 having the W-top 414 connection to the marker link 20, the struts and / or U-tops adjacent to the top and bottom of the marker structure are shown to be separated by a distance greater than the maximum width (ts) of the marker structure when the scaffold is crimped to D-min. No overlap occurs when the scaffold having the ring 412 is crimped to D-min. The marker link is anywhere between the top and the strut when the scaffold is crimped to approximately D-min.

[0116] [

[0108] ]When following a simulated calcified tortuous anatomical model of a thin-walled scaffold similar to scaffold 300, it has been found that distortion of the distal ring was observed due to the strut being lifted and caught on an obstacle along its path. In addition, the marker structure 21 and the holes 22 were deformed / stretched, and as a result, there was a possibility that the marker material would fall off. To address concerns about separation of the marker material from this thin-walled scaffold, the bending flexibility of the marker link can be increased by extending the marker link and / or narrowing the width of the link portion connecting the structure 21 to the adjacent Y-top or w-top. As a result of this modification, the hinge region adjacent to the marker structure 21 becomes more flexible, thereby localizing the deformation to a point away from the structure 21 and protecting the marker holes 22 from significant deformation. This modification also makes the distal end and / or proximal end of the scaffold more flexible and adaptable to ballooning, thereby reducing the likelihood that the strut will be lifted and caught on an obstacle during introduction to the target site.

[0117]

[0109] Figure 5 shows another embodiment of the scaffold, namely an enlarged view of the scaffold 500. The view of Figure 5 is the same as section IVC of Figure 4, and the scaffold 500 has all the features of the scaffold 400 except that the marker links connecting the ring 412a and the ring 312b and the marker links connecting the ring 412b and the ring 312f are changed. The marker link 520 is different from the marker link 20 in that an additional link 520b is added, that is, the existing link on the right side of the marker structure 21b (see the marker link 20) is extended. This added or extended marker link portion results in an increase in the distance A12 compared to the case where the marker 20 is used. Also, the distance A12 is longer than the distance A23 separating rings that are not connected by the marker link, for example, the ring 312b and the ring 312c in Figure 5. The same modified marker link 520 that replaces the marker link 20 is made for the marker link extending between the ring 412b and the ring 312f. The marker link 520 may replace the marker link 20 of the scaffold 300 (both at the proximal end and the distal end). In such a case, the same features discussed for the scaffold 400 with the link 520 also apply to the scaffold 300 with the link 520.

[0118]

[0110] It has been found that when the link 20 is replaced with the marker link 520, the radiopaque material held by the marker structure 21 is less likely to fall off or separate from the scaffold when the scaffold is crimped, balloon-expanded, or follows a tortuous blood vessel. The reason for the improved retention can be understood by considering the strain energy distribution on the link when the scaffold is deformed or when the y-top 316 of the ring 312b moves relative to the w-top of the ring 412a.

[0119]

[0111] When the top 316 of the ring 312b moves radially outward or inward with respect to the top 414 of the ring 412a, or when the top moves in the opposite direction along the axis B-B, the marker link 20 deforms. A significant portion of the strain energy of the link 20 resulting from this deformation is retained in the marker structures 21a, 21b because the left and right link portions of the structure 21 are relatively short and thick (thus, there is little deformation in this portion of the marker link, and thus little strain energy is retained here). The load must be reacted somewhere along the marker link when the ring movement is forced (i.e., the ring movement is caused by a forced displacement or overwhelming force, for example, by the jaws of a crimper closing on a scaffold, so the rings will move relative to each other by a defined amount regardless of the link stiffness), so most of the strain energy is retained in the marker structure 21, which is more deformable than the short and thick link portions near the top. This deformation can change the shape of the hole in which the marker material is located, resulting in a loss of the holding force. By extending the link portion of the marker 20 or by adding a link 520b that is significantly longer than the link 520a representing the length of the left and right link portions of the structure 21 of the link 20, the strain energy retained in the structure 21 rather decreases, and the strain energy retained by the link 520b becomes more. As a result, the marker hole 22 retains its shape during these load events, reducing the tendency for the marker material to fall out during crimping or bending of the scaffold. In other words, most of the link deformation occurs in the elongated portion 520b, so that the hole 22 can retain its shape. In addition, the link 520b increases the flexibility of the link, thereby making it easier for the ring 312b or the ring 312f to move more easily relative to the ring 412a and the ring 412b, respectively. This aspect is advantageous for avoiding the problem that the distal end ring flares out or protrudes from the balloon when the catheter is fed around a dense vasculature (objective (iv) above). Also note that the marker 720 discussed in connection with FIG. 7 similarly addresses objectives (iv) and (iii).

[0120]

[0112] According to one example, the link 520b forming the y-top 316 has a thickness (tm2) that is approximately 60% less than the thickness (tm1) of the link portion 520a forming the w-top 414. Additionally, the length A12 is approximately 27% longer than the length A23 so as to accommodate the link 520 having the additional link portion 520b.

[0121]

[0113] When the calcified meandering anatomy model simulated on the thin-walled scaffold crimped to the introduction system was traced, distortion of the distal ring due to the strut catching on an obstacle along its path was observed. To understand the possible causes of the strut catching, the thin-walled scaffold was crimped to the introduction system of the same configuration and placed in the same bent state as that present in the anatomy model observed under the microscope. It was observed that the balloon was compressed at the inner curvature of the bend and was under tension at the outer curvature of the bend. Under tension, the balloon stretched to conform to the curve. When the w-top associated with the marker link was accidentally positioned at the outer curvature of the bend, the w-top did not conform to the curved balloon material below at the distal end 15a but flared outwardly (see FIG. 6B). The w-top portion of the scaffold remains straight because it is rigid due to the marker material and structure 21.

[0122]

[0114] Figure 6 shows a partial plan view of the end portion of another embodiment of a scaffold, namely scaffold 600. The left or distal end portion 602 (i.e., the left side of FIG. 6) includes sinusoidal rings 312a, 412b, and 312c, with ring 312a being the outermost ring. The right or proximal end portion 604 (i.e., the right side of FIG. 6) includes sinusoidal rings 312d, 412b, and 312f, with ring 312f being the outermost ring. As can be understood from FIG. 6, the distal end portion 602 is different from the proximal end portion 604. This modification to scaffold 300 or scaffold 400 is made to address the occurrence of a non-compliant distal outermost end ring when the scaffold mounted on the balloon catheter is sent through a sharp bend angle in the vasculature.

[0123]

[0115] The proximal end portion 604 of scaffold 600 is the same as the proximal end portion 304 or proximal end portion 404 respectively associated with scaffold 300 and scaffold 400. The distal end portion 602 is modified from the distal end portion 302 or distal end portion 402 as follows.

[0124]

[0116] The (distal) marker link 20 or marker link 520 is located between the inner distal end ring 412a and the inner distal end ring 312c, in contrast to the (proximal) marker link 20 or 520 located between the outermost distal ring 312f and the inner ring 412b. This modification to the distal end 602 is desirable for at least one of the following reasons (a) and reason (b). (a) Improvement in adaptability to the distal balloon: Marker link 20 has a higher bending stiffness than link 634, or for that matter, link 334, and as a result, it may cause separation of the outermost ring distal to the balloon distal end. If it is not desirable to change the marker link structure, or if it cannot be achieved (for example, because the structure is required to provide a sufficient surface area to hold a radiopaque material of a desired volume), significantly reducing the bending stiffness of the link connecting the outermost ring 312a to the inner ring 412a can be achieved by moving the marker link 20 between the inner rings. In this way, the bending stiffness between the two outermost rings 312a can be dramatically reduced (objective (iv)). (b) Reduction of strain in the marker holding structure: When the scaffold is sent through a sharp bend angle, the outermost ring undergoes the greatest strain as the scaffold bends. In scaffold embodiments where it is not desirable to lower the bending stiffness of the outermost ring relative to the adjacent inner ring (for example, to avoid a reduction in the radial stiffness of the outermost ring, which may occur when the connecting link is extended to make both more flexible, or when it is important to avoid an increase in the spacing between the rings for drug coating or vascular support), by moving the marker link 20 to a position between the inner rings, the bending strain applied to the link 20, which may cause the marker material to fall off, is avoided or reduced. That is, since the bending strain of the scaffold (which occurs when the catheter makes a sharp turn) is greater between the outermost ring and the adjacent inner ring than between the inner rings, by placing the link 20 between the inner rings (without the need to change the marker link structure), the bending strain applied to the marker structure 21 is reduced. Objectives (ii) and (iii) are met.

[0125]

[0117] Also, the scaffold 600 is different from the scaffolds 300 and 400 also in the link type used to connect the outermost ring to the inner ring, i.e., the link 634 that connects the ring 312a to the ring 412a. The outermost distal ring 312a is coupled to the ring 412a by three non-linear link struts 634 that are significantly more bend-flexible than the link strut 334 that connects the inner rings. This also contributes to reason (a) for using the scaffold 600 pattern at the distal end.

[0126]

[0118] The non-linear link struts can take various shapes, but are subject to some constraints such as providing sufficient spacing for crimping, such as a D-min crimp profile. The type shown in FIG. 6 has a U-shaped intermediate portion 636 connected to the respective y-top and w-top by a short straight link portion and a long straight link portion, respectively. The link portion 632a that connects the portion 636 to the w-top is longer than the link portion 632b that connects to the y-top in order to provide sufficient clearance to the ring strut during crimping (as will be described later). Because this clearance is provided, the w-top 309 formed by the link portion 632a can be crimped to D-min without the U-shaped portion 636 interfering with the strut 330 or the strut 330 overlapping the U-shaped portion 636.

[0127]

[0119] Referring to FIG. 6A, the crimp side profile of the scaffold 600 is shown. The long straight link portion 632a and the short straight link portion 632b of the link 634 are shown together with the U-shaped intermediate portion 636. The length A12 (measured with respect to the axis A-A) is approximately longer than the length A23 by the length of the U-shaped portion 636, or the sum of the lengths of the portion 632a and the portion 632b is approximately equal to A23 minus the strut width of the ring. In one example, the length A12 is about 40% longer than the length A23.

[0128]

[0120] In other embodiments, the U-shaped portion 636 can be replaced with a link having a smaller moment of inertia by the region between portions 632a and 632b, an S-shaped notch portion that replaces the U-shaped portion, or a narrowed portion. Examples of these link types are described in FIGS. 14B, 14C, 14D, 14E, and 14F, and the accompanying paragraphs

[0223] -

[0229] of U.S. Patent Application Publication No. 2014 / 0039604. The term "non-linear" link strut means any of these links.

[0129]

[0121] FIG. 6B is an image showing a deformed distal end of a medical device including a balloon catheter having a shaft 2 and a scaffold 10 crimped to the balloon 15. As can be seen from this figure, when the catheter is induced to have a sharp bend (when tracing on a guidewire), the distal end of the balloon and the shaft adapt to the turning angle, but the distal end 7 of the scaffold does not. More specifically, the outermost ring 5 flares or protrudes outward from the distal end. This protruding structure 5 can catch on the wall of the vascular system. The most immediate concern associated with this orientation of the scaffold relative to the distal end of the balloon is the damage that can be caused by the ring 5 catching on the vascular system and damaging the scaffold (due to excessive bending strain). The possible damage has been described above. First, the marker link structure can be deformed, resulting in the loss of the marker material. Second, the strain can result in the breakage of the ring 5, or the occurrence of breakage or crack propagation within the ring 5.

[0130]

[0122] One solution to this problem is to increase the bending stiffness of the end ring so that due to blood vessel occlusion, a space is created at the flared or protruding scaffold end. For example, the end ring could be made thicker or the number of connecting links between the outermost ring and the inner ring could be increased. However, preferably, instead, the stiffness of the ring is decreased so that the scaffold end adapts to the balloon distal end. Also, for the reasons described above, it is also preferable to limit the load on the marker link. The scaffold 600 (or the following scaffold 700) meets this requirement.

[0131]

[0123] FIG. 6C is an image of the scaffold distal end 602 attached to the distal end 15a of the balloon 15 when the catheter makes a similar sharp turn in the vascular system. As shown, by reducing the bending stiffness of ring 312a relative to the inner ring (ring 312b), the end ring 312a adapts to the shape of the balloon distal end 15a. The end ring 312a does not flare out or protrude as in the case of the scaffold 5. The link 632 acts as a hinge that accommodates the compression and tension that the bend would exert on the distal end ring when the crimped scaffold is placed at the bend.

[0132]

[0124] Also, the distal end scaffold adaptability to the balloon distal part can also be achieved by changing the marker link structure so that the bending flexibility is higher. In fact, according to this consideration, the w top formed by the marker link can significantly reduce the stiffness at the w top associated with the marker link 314. In that case, the thin-wall scaffold design can connect the marker link to the outermost ring without the above-mentioned flare ring problem.

[0133]

[0125] Figure 7 shows a partial plan view of the distal portion of another embodiment of the scaffold, namely scaffold 700. The left or distal end portion 702 (i.e., the left side of FIG. 7) includes sinusoidal rings 312a, 312b, and 312c, with ring 312a being the outermost ring. The right or proximal end portion 704 (i.e., the right side of FIG. 7) includes sinusoidal rings 312d, 412b, and 312f, with ring 312f being the outermost ring. As can be understood from FIG. 7, the distal end portion 702 is different from the proximal end portion 704. This modification to scaffold 300 or scaffold 400 is also made to address the occurrence of the non-compliant distal outermost end ring when the scaffold attached to the balloon catheter is sent through a sharp bend angle in the vasculature.

[0134]

[0126] The proximal end portion 704 of the scaffold 700 is the same as the proximal end portion 304 or 404 respectively associated with scaffolds 300 and 400. Further, the distal end portion 702 shares some of the characteristics of the scaffold 600 at the distal end portion 602, except as follows.

[0135]

[0127] In contrast to marker links 20 or 520 located between the inner links in the case of scaffold 600, marker link 720 (FIG. 2B) is located between the outermost ring 312a and the inner ring 312b. The marker links of scaffold 700 are also different from the marker links of the previous embodiments. Marker link 720 has a marker structure 21 oriented vertically, rather than horizontally as in the case of marker link 20 or link 520. That is, marker structure 21a is offset from marker structure 21b along axis B - B, rather than axis A - A. There is a long straight link portion 732a connecting the structure 21 at one end to form the w top 314, and a short link 732b at the opposite end forming the y top 316.

[0136]

[0128] The outermost ring 312a of the distal end portion 702 of the scaffold is connected to the inner ring 312b by one marker link 720 and two non-linear links 634 used for the scaffold 600. The combined inner ring is not connected by either the marker link 720 or the link 634. Link 334 is used. The marker link 720, in contrast to the marker link 20, has higher bending flexibility due to the length of portion 732a and is advantageously arranged between the outermost ring and the adjacent inner ring so that the end of the scaffold can be more easily positioned under fluoroscopy. In addition, when marker 720 is used, there are one or more of the following advantage functions. First, the marker is more flexible so that the outermost ring can more easily conform to the balloon when the catheter is sent through a sharp bend angle in the vascular system. In this sense, marker 720 has some of the same advantages as marker 520 (objective (ii) and objective (iii)). Also, there is no need to modify the ring structure to enable crimping of the ring with a w-top formed by the marker link. Since structure 21 does not interfere with ring structure 21, ring 312a can be crimped to D-min (objective (i)).

[0137]

[0129] Figures 6A and 7A show the crimped state of the scaffold 700 near the marker 720 and the link 634, and the lengths A12 and A23 between the rings. As can be seen from these figures, the portions 732a of the marker and the link and the portion 632a have lengths that allow the outer ring 312a to be crimped to D-min without interference from either the U-shaped portion 636 or the marker structure 21. As can be seen from these figures, the structure 21 having the hole 22 and the U-shaped structure 636 is between the U-top adjacent to the W-top of the left ring and the U-top adjacent to the Y-top of the right ring.

[0138] Referring to FIG. 7B, an enlarged view of section VII of FIG. 7 is shown. As shown, the respective lengths of portion 732a and portion 732b are c1 and c2. The lengths of portion 632a and portion 632b are also c1 and c2. The length A12 and length A23 of the scaffold 700 are also shown (the length A12, length A23, length c1, and length c2 also apply to the lengths of portion 632a and portion 632b of the scaffold 600 and the ring spacing). The sum of length c1 and length c2 is equal to A12 minus the length of the U-shaped portion 636 and the width of the top. In some embodiments, A12 is approximately 40% larger than A23, and c1 is approximately 36% longer than c2. The length c1 is approximately equal to the distance between the valley of the adjacent top and the w-top formed by portion 732a or portion 632a minus the width of the top 314 or strut 330 when the scaffold is in the crimped state (see FIGS. 6A - 7A). The marker structure is located to the right of the U-top adjacent to the W-top formed by the marker link.

[0139] FIG. 7C is an image of the distal end 702 of the scaffold attached to the distal end 15a of the balloon 15 when the catheter makes a similar sharp turn in the vasculature. As shown, by reducing the bending stiffness of ring 312a with respect to the inner ring (ring 312b), the end ring 312a conforms to the shape of the balloon distal end 15a. The end ring 312a does not flare out or protrude in a flared manner as in the case of the scaffold 5.

[0140] Table 2 shows the dimensions associated with an example of a fabricated scaffold corresponding to the illustrated embodiment of the scaffold (when the entry is "-", it means the same value as the column to the left. Thus, the value of tm2 for the scaffold 400 is 217, and the length B1 of the scaffolds 500 and 700 is 374 and 78, respectively).

Table 2

[0141]

[0133] Referring to Table 2, as can be understood from the above examples, with respect to the scaffold 300, as compared with the scaffolds 400, 500, 600, and 700, as previously described, depending on the introduction of the scaffold through the crimped and / or serpentine artery, the wavelength, 1 / 2 wavelength, marker link thickness, length, and orientation, the type and length of the non-marker link, the ring spacing, and the top width in the marker link are respectively changed. These relationships apply to the thin-walled scaffold whether in the crimped state or prior to the crimped form. Thus, when referring to the crimped scaffold, the above relationships also hold. It should also be understood that the features of the scaffolds 400 and / or 500 different from the scaffold 300 can be incorporated into the scaffolds 600 and 700. Alternatively, the features of the scaffolds 400 and / or 500 may not be included in the patterns of the scaffolds 600 and 700.

[0142]

[0134] The following considerations mainly relate to fulfilling objective (ii): fixing a radiopaque material to the scaffold holes provided by the marker structures 21a, 21b. As previously mentioned, it has been discovered that in a thin-walled scaffold, the marker material cannot be reliably held in the marker holes by frictional engagement with the walls of the cylindrical holes. To satisfy objective (ii), in a preferred embodiment, the radiopaque material is fixed to any of the scaffolds 300, 400, 500, 600, or 700 by installing a rivet-like marker material body in the marker structures 20, 520, or 720 without interfering with any of the other objectives (i), (iii), or (iv). The attachment and fixation of the marker do not include, in some embodiments, the addition of any polymer, adhesive, or reformation of the cylindrical hole (other than the deformation occurring during the installation process). In a preferred embodiment, a drug-polymer coating is applied after the marker is placed in the hole.

[0143]

[0135] Instead of the spherical marker 25 for the cylindrical hole, a rivet-shaped marker is used. Figures 8A and 8B show a side view and a top view of the rivet-shaped marker 27. The head 28 can include the anti-luminal side 27a or the luminal side 27b of the rivet 27. In the drawing, the head 28 includes the anti-luminal side 27a. It would be preferable to make the head 28 the luminal side portion of the rivet 27 for assembly. This is because then the scaffold can be placed on the mandrel and the tip portion of the rivet deformed by a tool (such as a pin) applied externally to the anti-luminal side of the scaffold. The rivet 27 has a head diameter d1, and the diameter d2 of the shank 27c is approximately equal to the diameter of the hole 22. The height of the head 28 is h2, which is the amount by which the head 28 will extend beyond the anti-luminal side 22a of the strut portion 21a. Although not desirable, extensions not exceeding about 25 microns (μm), that is, heads 28 extending from about 5 to 10 microns (μm) to about 25 microns (μm) from the anti-luminal side 22a, or extensions of the head by an amount of about 25% or less of the strut thickness, are also acceptable. A similar extension beyond the luminal side 22b is acceptable for the deformation of the tip of the rivet.

[0144]

[0136] Referring to Figure 9, the rivet within the hole 22 is shown. The rivet 27 is fixed to the hole 22 by the deformed tip portion 27b'. The overall height h1 is preferably about 40% or about 10% - 40% or less of the strut thickness (t), and the height of the tip portion is approximately the same as the height h2 of the head or within 5 - 20 microns (μm) compared to the height h2 of the head.

[0145]

[0137] The rivet 27 can be attached to the hole 22 of the strut portion 21a by first inserting the rivet 27 into the hole 22 from the inner cavity side of the scaffold so that the head 28 is placed on the lumen side surface 22b of the strut portion 21a. The scaffold is then slid over an interference fit mandrel. With the mandrel surface pressed against the head 28, a tool (such as a pin) is used to deform the tip portion 27b to produce the deformed tip portion 27b' of FIG. 9. In some embodiments, the rivet 27 can first be inserted into the hole 22 from the anti-lumen side so that the head 28 is placed on the anti-lumen side surface 22a of the strut portion 21a. With the head 28 held in place by a tool or flat surface applied to the anti-lumen side surface, the tip portion 27b is deformed by a tool, pin, or mandrel inserted into the lumen or passing through the scaffold pattern from an adjacent position on the anti-lumen side surface. In some embodiments, the rivet 27 can be a solid body (FIGS. 8A-8B) or a hollow body. For example, the shank is a hollow tube and the opening extends through the head 28 of the rivet.

[0146]

[0138] In some embodiments, the rivet is a hollow or solid cylindrical tube and has no pre-made head 28. In these embodiments, the tube (solid or hollow) can first be fitted into the hole and then a tightening tool can be used to form the head and tip portions of the rivet. According to a preferred embodiment, there is a method for fabricating a radiopaque marker as the rivet and attaching the rivet to the scaffold, and a scaffold with such a marker attached. First, a method for fabricating a rivet-shaped marker from beads will be described.

[0147]

[0139] As described above, the head and tip portions of the marker contribute to holding the marker in place when an external force is applied to the rivet, when the link structure is deformed during crimping or balloon expansion, or when the scaffold makes a sharp turn in the vasculature. However, in some embodiments, the tip portion of the rivet 27' in FIG. 9, for example the tip portion 27b', does not exist. Instead, the shank portion of the rivet is deformed so as to have a trapezoidal shape or a frustum shape, or the end is enlarged (for example, the rivet 137' shown in FIG. 15A). This type of marker has been found to increase its resistance so as not to be pushed out of the holes in the struts or links when the scaffold receives an external force that deforms the links or struts that hold the marker.

[0148]

[0140] It is desirable to select an appropriate size of the beads for forming the rivet. According to some embodiments, the bead size to be used, i.e., the bead volume, depends on the thickness (t), hole diameter (D2), distance between holes (D1), and peripheral thickness (D2) of the struts of the scaffold structure to which the rivet is attached (for example, the link strut having the hole 22 in FIG. 2A or FIG. 2B). The raw material may be spherical or cylindrical. The raw material made of a radiopaque material can be obtained from a commercial source.

[0149]

[0141] According to the present disclosure, the raw material beads are used to make rivet markers for attachment to the scaffold holes 22. In a preferred embodiment, the rivet marker is attached or engaged to the scaffold holes of thin struts or links preferably having a thickness (t) of less than about 100 microns (μm). The rivet making process and the steps of attachment to the scaffold can be summarized as a six-step process.

[0150]

[0142] Step 1: Select marker beads from the raw materials that have a diameter or volume within the desired range, i.e., a diameter or volume suitable for attachment to the scaffold according to each dimension of D0, D1, D2, and t (Figure 2B). The selection of marker beads having the desired diameter or volume, or the removal of beads that are too small from the lot, can be performed using a wire mesh sieve. A set of beads is sieved on the wire mesh sieve. Beads that do not have the smallest diameter or volume fall through the openings of the wire mesh sieve. Alternative methods known in the art may be used to remove unwanted beads or select beads of the appropriate size.

[0151]

[0143] Step 2: Place the beads selected in Step 1 on the die plate.

[0152]

[0144] Step 3: Cold form the rivet from the beads by pressing the beads into the die plate. At a temperature close to the ambient temperature, (e.g., using a plate, mandrel head, pin, or tapered ram head) push the beads through the die to reshape the beads into a rivet defined by the shape of the die and the volume of the beads relative to the volume of the die that receives the beads.

[0153]

[0145] Step 4: Remove the formed rivet from the die plate. The formed rivet has a total length of about 190 - 195 microns (μm) and a diameter of about 300 - 305 microns (μm) and is removed using a tool with a vacuum tube. The air pressure is adjusted to grip the rivet or release the rivet from the tip. The rivet is removed from the die by placing the opening of the vacuum tube above the head of the rivet, reducing the air pressure inside the tube to attach (by the pressure difference) or suck the head to the tip of the tube, and lifting the rivet from the die.

[0154]

[0146] Step 5: With the rivet attached to the tip of the tube, move the rivet to be positioned above the hole in the scaffold, place the rivet in the hole using the same tool, and then raise the air pressure within the tool to ambient air pressure. The rivet disengages from the tool.

[0155]

[0147] Step 6: Deform the rivet and / or the hole to engage or enhance the resistance to the marker dropping out of the hole, e.g., FIGS. 14A - 14C.

[0156]

[0148] According to Steps 1 - 6, it will be understood that the problems of handling non - spherical beads are overcome. For example, in Steps 1 - 6 above, there is no need to re - orient the rivet after it is formed from spherical beads, and the problem of orienting the spherical beads to align them and place them in the hole is overcome.

[0157]

[0149] Referring to FIGS. 16A, 16B, and 16C, steps associated with moving the formed rivet 127’ (or 137’) from the die 200 (or 205) to the scaffold strut hole 22 using a vacuum tool 350 are shown. As will be appreciated, the formed radiopaque marker 127’ is extremely small, i.e., its maximum dimension is less than 1 millimeter, and thus the handling and orientation of the marker 127’ for placement in the hole 22 is complex (as opposed to placing a sphere in a hole) because the shank needs to be properly oriented with respect to the hole. For this reason, the installation or forging process is combined with removing the rivet 127’ from the hole 200 using the tool 250, maintaining the orientation while the rivet 127’ remains attached to the tool, FIGS. 16B - 16C, and then placing the rivet 127’ in the hole 22a, FIG. 16C, for placement into the scaffold hole.

[0158] Referring to FIGS. 10 and 11A, a first embodiment in accordance with the present disclosure of die 200 and marker 127 formed using die 200 is shown. The die is a flat plate having an upper surface 201 and a through hole extending from the upper end 201 to the lower end. The hole has an upper end diameter dp2 and a lower end diameter dp1 that is less than dp2. The hole 202 is preferably circular throughout, but in other embodiments, the hole may be rectangular or hexagonal throughout the thickness tp, in which case dp1 and dp2 are the lengths or dimensions across the hole (rather than diameters). The plate 200 also has a height tp. The taper angle is related to dp2 and dp1 by the equation tanФ = (1 / 2(dp2 - dp1) / tp), and in a preferred embodiment, φ is 1 to 5 degrees, 5 to 10 degrees, 3 to 5 or 2 to 4 degrees. The shape of die 200 produces a frustoconical shank as shown in FIG. 18A. The beads are placed at the upper end of the opening 202 such that the raw material beads (not shown) are partially located within the hole 202. Then, a flat plate, mandrel or pin ("ram head") is pushed into the top of the beads such that the beads are pushed into the hole 202. The beads are pushed into the hole until the ram head is at a distance of approximately HH from the surface 201. The rivet 127 formed from the foregoing forming process has a taper angle Ф over the entire shank height SH, or a substantial portion thereof, and the shank shape is frustoconical. The overall height of the rivet is HR, the head thickness is HH, and the head diameter is HD. In some embodiments, the angle Ф may be small enough such that the shank is treated as a cylinder or such that Ф is approximately zero.

[0159]

[0151] Referring to FIGS. 12 and 13A, a second embodiment of die 205 and marker 137 formed using die 205 according to the present disclosure is shown respectively. The die is a flat plate having an upper surface 206 and a hole extending from an upper end 301 to a lower end. The hole has a constant diameter dcb1 throughout. A countersink is formed in the upper end 206. The countersink diameter is dcb2. The hole 207 is preferably circular throughout, but in other embodiments the hole 207 may be rectangular or hexagonal, in which case dcb1 is the length or size across the hole (not the diameter). The shape of die 205, as shown in FIG. 13A, produces a rivet with a stepped cylindrical shape or a cylindrical shank with a head. Beads (not shown) are placed at the upper end of the opening 207 such that the raw beads are partially located within the hole 207. Then, a ram head is pushed into the top of the beads so that the beads are pushed into the hole 207. The beads are pushed into the hole until the ram head is at a distance HH from the surface 206. The rivet 137 formed from the above-described forming process takes the shape shown in FIG. 13A. The overall height of the rivet is SH + HH, the head thickness is HH, the shank height is SH, and the head diameter is HD.

[0160]

[0152] Tables 3 and 4 below provide examples of rivet dimensions for rivets to be fixed within link holes 22 as shown in FIG. 2A. In this example, the thickness of the link is 100 microns (μm), and the values of D0, D1, and D2 in microns (μm) are 241, 64, and 64 respectively.

[0161]

[0153] The values of the dimensions tp, dp2, and dp1 of die 200 are 178, 229, and 183. The dimensions of the formed rivets obtained using die 200 are shown in Table 3. As can be understood from the results, the shank length (or height) is greater than 150% of the link thickness, and the rivet head diameter (HD) is significantly larger than the diameter of hole 22. The lower part of the shank is utilized to form the tip portion of the rivet. The average values and standard deviations of HD, SD, and SL are based on the measured rivets of each "n" sample.

Table 3

[0162]

[0154] The values of the dimension dcb2 and the dimension dcb1 of the die 205 are 305 and 203. Table 4 shows the dimensions of the formed rivets obtained using the die 300. The average values and standard deviations of HD, SD, HH, and SL are based on the measured rivets of each “n” sample.

Table 4

[0163]

[0155] In Tables 3 and 4, the “O.D. rivet head diameter after installation” refers to the outer diameter of the rivet marker head after the rivet marker is pushed into the scaffold hole.

[0164]

[0156] Next, an example of a process for attaching either rivet 127 or 137 to the scaffold hole 22 will be considered. According to some embodiments, the rivet shank is placed in the hole 22 from the anti-lumen side or the outside of the scaffold, so that the head is located on the anti-lumen side surface 22a. The rivet may alternatively be placed from the lumen side of the hole. The rivet is firmly pushed into the hole such that the largest portion of the shank extends from the lumen side or the anti-lumen side, respectively.

[0165]

[0157] After the rivet 127 is disposed in the hole 22, the side opposite the head is subjected to an installation process. Referring to FIG. 11B, a cross section of the deformed rivet 127' in the hole 22 is shown. The rivet 127' has a head 127a' that extends by an amount h2 from the surface 22a. The length h2 may be about 25 microns (μm), 25 to 50 microns (μm), or 5 to 50 microns (μm). The same dimensions also apply to the tip portion 127b' that extends from the surface on the opposite side of the link (e.g., the lumen side). The diameter of the head 127a' may be larger than that of the tip portion, or the diameter of the tip portion 127b' may be larger than that of the head 127a'. The tip portion is formed from the extended shank length that protrudes from the link surface by installation. The tip portion 127b' is formed by installation. For example, the rivet 127 is disposed from the surface 22a (anti-lumen side) such that a substantial portion of the shank length, e.g., 50% of the strut thickness, extends from the lumen side. A cylindrical mandrel (not shown) is disposed through the lumen of the scaffold. This mandrel has an outer diameter slightly smaller than the inner diameter of the scaffold and provides an installation surface for forming the tip portion 127b'. The mandrel is rolled back and forth over the shank portion that extends from the lumen side. By this operation, the shank material is flattened around the hole, and the tip portion 127b' is generated. The resulting rivet 127' is fixed in place by, at least in part, the resistance of the tip portion 127b' that attempts to push the rivet towards the anti-lumen side of the hole and the resistance of the head portion 127a' that attempts to push the rivet towards the lumen side of the hole 22. As shown in the figure, due to the deformation of the shank, a tip portion 127b' having a flange disposed on the surface 22b is generated. The flange may be circular like the head and may have a flange radial length that is larger or smaller than the radial length of the flange of the head 127a'.

[0166] Referring to FIGS. 15A and 15B, a stepped mandrel is used with a ram head to produce a rivet 137 from a rivet 137'. The rivet has a shank 137' that is reformed from a generally cylindrical shape, such as when using the die 205 of FIG. 12, to the shape shown in FIGS. 15A-15C. This shank shape can be characterized by a taper angle θ of about 5-15 degrees, 5-9 degrees, or about 3-8 degrees. The shank according to some embodiments of the rivet in hole 22 is frustoconical in shape, and the opposite or distal shank end, i.e., end 137b', is larger or has a larger diameter than the proximal or the shank portion closest to the head 137a'. The deformed shank 22' may have a shank diameter S2 closest to one of the luminal or abluminal openings of hole 22' that is larger than the shank diameter S1 closest to the other of the luminal or abluminal openings, i.e., S2 > S1. According to some embodiments, as shown in FIG. 15A, the cylindrical hole 22 is also deformed into a hole 22' having an opening at surface 22b that is larger than the hole opening at surface 22a. According to some embodiments, the hole 22 and the rivet 137 are deformed when the rivet 137 is attached to the scaffold.

[0167]

[0159] The structure shown in FIG. 15A can be produced by a second process of attaching a rivet marker to the scaffold hole 22. In contrast to the first process, the tool does not roll over the entire surface where the shank tip portion protrudes from the hole opening. Instead, the shank tip portion is directly pressed against a non-compliant surface that can be the surface of a metal mandrel. The rivet is deformed by the compressive force between the surface of the mandrel and the head of the ram 234 that presses the rivet against the mandrel surface. The first process of generating the deformed rivet 127' is, in contrast, formed by a combination of rolling on a hard surface and inserting into the shank and restraint against the head 127a, whereby the rivet head is held against the surface 22a while the tip portion 127b is seated. Under the second process, the line of action of the force is completely along the axis of the rivet or perpendicular to the rivet head. As a result, little or no flange or periphery is formed from the tip portion of the shank, the shank portion is flattened or widened, and the hole is deformed.

[0168]

[0160] Next, the second step will be described in more detail with reference to FIGS. 14A to 14C. The scaffold 400 is placed on the stepped mandrel 230. This mandrel has a first outer diameter and a second outer diameter smaller than the first outer diameter. The scaffold portion holding the marker 137 is placed on the smaller diameter portion of the mandrel 230. The larger diameter portion of the mandrel 230 holds the adjacent portion of the scaffold. The smaller diameter portion of the mandrel 230 has a surface 230a, and the larger diameter portion has a surface 230b. As shown in FIGS. 14B and 14C, the ram 234 pushes the scaffold portion 230a holding the marker 137 into the mandrel surface 230a with a force F (FIG. 14B), whereby the scaffold end deflects by a distance "d" toward the surface 230a (FIG. 14A). After the scaffold reaches the surface 230a, the ram 234 continues to push in the scaffold portion holding the marker (by directly pushing the head 137a), creating the deformed marker 137' and hole 22' as shown in FIG. 15A. The selected surface 230a may be smooth or may have no grooves, pitting, depressions or other surface irregularities (other than the cylindrical surface) that would impede the flow of material during installation. In a preferred embodiment, the mandrel surface is smoother compared to the surface of the head 234 pressed into the rivet marker 137. That is, the coefficient of friction (Mu) between the head 234 and the surface 137a' is greater than the Mu between the surface 230a of the mandrel 230 and the surface 137b'.

[0169]

[0161] The shapes of the deformed shank 137’ and hole 22’ shown in FIG. 15B produced a greater extrusion force than previously thought (where “extrusion force” means the force required to remove the marker from the hole). In fact, unexpectedly, it was discovered that the deformed rivet 137’ and hole 22’ have a greater resistance to dropout than a marker fitted to a link having a thickness 50% greater, regardless of the presence or absence of the head 137a’. For example, a test of the minimum dropout force required to push the rivet 137’ out of the side 22a of the hole 22’ of a strut having a thickness of 100 microns (μm) was about 50% greater than the dropout force required to push out a marker attached to a hole (158 microns (μm) vs. 100 microns (μm)) in a strut having a greater thickness, according to U.S. Patent Application Publication No. 2007 / 0156230 (FIGS. 8A, 8B, or when the ball deforms more cylindrically during storage such that surface-to-surface contact is increased to a maximum). This is as shown in Table 4.

Table 5

[0170]

[0162] The scaffold A has more surface area for contact with the marker and thus has a greater frictional force that resists detachment. Nevertheless, the scaffold B has a greater extrusion force. What this result shows is that the deformation that occurs during the riveting process resulting in the deformed rivet marker and hole in Figure 15A has a significant impact on the extrusion force (note: the weight gram extrusion force reported in Table 4 was applied to the lumen side 22b of the scaffold B). Considering a wall thickness 50% greater, the scaffold A should have had a greater detachment force (the same bead material, bead volume, and poly(L-lactide) scaffold material for both scaffold A and scaffold B). The greater detachment force can be explained by the deformed shank and hole shape that essentially creates a lower portion 137b’ that is significantly larger than the opening 22a of the strut 22. Thus, the detachment force must be large enough to deform the opening 22a’ and / or the shank portion 137b’ in order to detach the marker from the 22a side of the hole 22’ (not only to essentially overcome the frictional force between the material and the hole wall).

[0171]

[0163] The shape 137’ in FIG. 15B can be formed by an installation process that deforms the rivet while the rivet is positioned inside the hole 22. The rivet can have the shape and / or characteristics of rivet 27, rivet 127, or rivet 137 before installation. During installation near the tip portion 137b’, the rivet material flows laterally (shear flow), causing the rivet material to expand and the strut hole to approach (enlarge) the opening 22b’. As a result, a trapezoidal or frustum-shaped form of the rivet shank and the hole is formed. In the installation process of FIGS. 14A - 14C, equal and opposite forces are applied that are substantially collinear with the axis of symmetry of the rivet (rather than rolling motion on one side). Instead of a rivet, a cylinder or sphere is placed in the hole 22, and there is a coefficient of friction (COF) between the installation surface 230a and the tip portion 137b that is approximately the same as the COF between the installation surface 234 and the head 137a. Otherwise, if it were the same installation process as in FIGS. 14A - 14C, the result would be a more symmetrically deformed marker, such as the shape shown in the specification of U.S. Patent Application No. 2007 / 0156230, for example, a cylindrical or barrel-shaped marker crushed according to the COF. This result can be understood by reading Kajtoch, J Strain in the Upsetting Process, Metallurgy and Foundry Engineering, Vol. 33, 2007, No. 1 (which discusses the influence of the coefficient of friction between the ram and the ingot on the resulting shape for aspect ratios greater than 2). The shape of the radiopaque material pushed into the hole, such as the rivet 137 vs. the sphere (scaffold A), etc. is also a factor. The presence of a head on one side causes the shank to form an asymmetric shape around the strut central plane axis. The combination of the rivet shape and the coefficient of friction difference is considered to have produced a favorable result.

[0172]

[0164] In a preferred embodiment, the smooth mandrel 230 surface 230a presses against the surface 137b as compared to the rougher surface of the head 234 pressing against the surface 137a. In a preferred embodiment, the coefficient of friction on the anti-lumen side was greater than 0.17, i.e., Mu>0.17, while the coefficient of friction on the lumen side was less than 0.17, i.e., Mu<0.17. As described above, the influence of the difference in the coefficient of friction can be explained by the shear flow near the ends in contact with the respective implant heads or the restraint on the subsequent material flow. When the coefficient of friction is low enough, the surface area does not remain relatively constant but expands laterally. Thus, since Mu is small on the lumen side, there is more lateral flow than on the anti-lumen side. The result, when combined with the use of the rivet shape, is thought to be the frustoconical shape of the disclosure as shown in FIGS. 15A-15B, which can be considered, for example, a shank with a fixed angle θ.

[0173]

[0165] There may be a heating step for the scaffold after marker placement. In some embodiments, this heating step may correspond to a recovery process of the pre-crimp scaffold polymer that removes the aging effect of the polymer.

[0174]

[0166] Heat recovery before the crimping step (including heat treatment of the bioabsorbable scaffold that is above TG but below the melting temperature (Tm) of the polymer scaffold) can reverse or remove the physical aging of the polymer scaffold and can reduce the number of crimp-induced damages and / or marker drop-offs (e.g., at the peaks of the scaffold).

[0175]

[0167] According to some embodiments, immediately before crimping the scaffold to the balloon and after placement of the marker, the scaffold is heat treated, mechanically strained, or solvent treated to induce recovery or elimination of polymer aging. Recovery erases or reverses changes in physical properties caused by physical aging by returning the polymer to a less aged or even unaged state. Physical aging brings the polymer closer to a thermodynamic equilibrium state, and recovery moves the material away from the thermodynamic equilibrium state. Thus, recovery can change the properties of the polymer in a direction opposite to that caused by physical aging. For example, recovery can cause a decrease in the density of the polymer (an increase in specific volume), an increase in the elongation at break of the polymer, a decrease in the modulus of the polymer, an increase in the enthalpy, or any combination thereof.

[0176]

[0168] According to some embodiments, recovery is desirable for reversing or eliminating physical aging of a previously processed polymer. However, recovery is not intended to remove, reverse, or erase the memory of previous processing steps. Thus, recovery neither trains nor imparts memory to the scaffold or tube. Memory can refer to transient polymer chain structures and transient polymer properties provided by previous processing steps. This includes processing steps for radially reinforcing a tube for forming a scaffold by inducing biaxial stretching of polymer chains in the tubes described herein.

[0177]

[0169] Regarding the integrity or resistance to detachment of the marker scaffold during crimping, the heating step has been found to help reduce cases where crimping causes marker detachment. According to some embodiments, any of the foregoing embodiments of the marker retained within the scaffold hole 22 can include a heating step after the marker is placed in the hole and immediately before crimping, e.g., within 24 hours after crimping. The scaffold has been found to be able to better retain the marker within the hole 22 after heating. Mechanical strain, such as limited radial expansion, or heat recovery (raising the scaffold temperature above the glass transition temperature (TG) of the load-bearing portion of the scaffold polymer for a short period of time), can have a beneficial effect on the structural integrity of the scaffold after crimping and / or after balloon expansion from the crimped state.

[0178]

[0170] In particular, these strain-inducing steps tend to have a beneficial effect on the dimensions of the hole 22 surrounding the marker when the hole is deformed as described above in connection with FIGS. 15A-15B.

[0179]

[0171] According to some embodiments, the scaffold after marker placement is heated to a temperature about 20 or 30 degrees above the glass transition temperature of the polymer for 10-20 minutes. More preferably, the load-bearing structure of the scaffold (e.g., a portion made from a polymer tube or material sheet) is a polymer comprising poly(L-lactide), and its temperature is raised to about 80-85 °C over 10-20 minutes after marker placement.

[0180]

[0172] According to some embodiments, it has been found that when the temperature of the scaffold is increased after placement of the marker, the portion of the hole 22 is reshaped to improve the fit of the marker into the hole. Referring to FIG. 15C, after the rivet marker 137 is placed in the hole 22 according to the second step, the hole shape is deformed to create a lip or edge 140 at the end 137b”, thereby creating a greater resistance to dislodgment than a scaffold marker structure that is not processed in the recovery step. The surface 140a of the lip 140 more strongly prevents dislodgment of the marker when force is directed towards the end 22b’.

[0181]

[0173] In accordance with the foregoing objective of achieving the desired crimp profile for a thin-walled scaffold, there is a method for crimping such a scaffold to a balloon that meets the following requirements: Structural integrity: Avoiding damage to the structural integrity of the scaffold when the scaffold is crimped to the balloon or when expanded by the balloon. Safe introduction to the implantation site: Avoiding dislodgment or separation of the scaffold from the balloon during transfer to the implantation site. Uniformity of expansion: Avoiding non-uniform expansion of the scaffold ring that can lead to structural impairments and a reduction in fatigue life.

[0182]

[0174] As previously reported in U.S. Patent Application Publication No. 2014 / 0096357, scaffolds are not as elastic as highly ductile metal stents. Thus, the need to meet all of the above requirements is particularly relevant for thin-walled scaffolds that are more likely to break during crimping or balloon expansion.

[0183]

[0175] Figures 17A - 17B show steps associated with a crimping process for crimping a balloon catheter (Figure 3D) to a thin - walled scaffold 300, 400, 500, 600, or 700 according to the present disclosure. It has been found that this crimping process can meet all of the above requirements for a scaffold crimped to D - min. In this example, a crimping process for crimping a 3.5 mm scaffold to a 3.0 mm semi - compliant PEBAX balloon is described. Figure 17B shows a graph of scaffold diameter versus time when balloon pressure in the form of a graph of the crimp portion of the flow of Figure 17A, i.e., balloon pressure of about 20 - 70 psi (or 1 atmosphere up to full inflation or over - inflation balloon pressure) is applied over substantially the entire crimping process. For example, the balloon pressure is maintained at 70 psi in steps A - G, and then decreased (or shrunk) to 50 psi (or 1 atmosphere) over period G - H. The balloon pressure is removed at point H. In steps H - J, no balloon pressure is used for the purpose of achieving a low cross - profile or crimping to D - min and avoiding balloon damage.

[0184]

[0176] Figure 17A shows three possible ways of crimping, as required. First, two balloons, balloon A and balloon B, are used. Balloon B is used in the (one or more) steps before crimping, and balloon A (used with the introduction system) is used for the final crimp. Second, only one balloon (balloon A) is used throughout the crimping process including an alignment confirmation inspection. In this case, the scaffold inner diameter is larger than the fully inflated or over - inflated balloon A. Thus, misalignment can occur on the balloon before crimping. Third, only one balloon (balloon A) is used throughout the crimping process without a final alignment confirmation inspection. In this case, the balloon for the introduction system has a fully inflated or over - inflated state that is approximately equal to the inner diameter of the scaffold inner diameter.

[0185]

[0177] Stage I: Place the scaffold supported on the fully inflated balloon of the balloon catheter within the crimper head. Inflate the balloon, and when the scaffold is supported in this state, substantially all of the creases are removed. In a preferred embodiment, the balloon of the catheter (i.e., the balloon used in the final product, the stent delivery system) is used for Stages I - II. In other embodiments, it may be preferred to use a second, larger balloon for Stages I and II (as detailed below). Heat the crimper blades to raise the temperature of the scaffold to the crimp temperature. In a preferred embodiment, the crimp temperature is between the lower limit of the glass transition temperature (TG) of the polymer and TG + 15 degrees.

[0186]

[0178] After the scaffold reaches the crimp temperature, close the crimper iris to reduce the scaffold inner diameter (ID) to a diameter slightly smaller than the outer diameter (OD) of the fully inflated or overinflated balloon (e.g., from 3.45 mm to about 3.05 mm for a PEBAX 3.0 mm semi - compliant balloon inflated to a diameter of about 3.2 mm). In this example, balloon B should be used for the diameter reduction to a 3.0 mm balloon size, or balloon A size (e.g., 3.0 mm balloon).

[0187]

[0179] Stage II: Hold the crimper jaw at a diameter of 3.05 mm and maintain this diameter over a second dwell period at the crimp temperature. After Stage II, the scaffold has approximately 90% of its pre - crimp diameter.

[0188]

[0180] In the aforementioned Steps I to II, the scaffold diameter is reduced to the size of the fully inflated balloon of the stent introduction system (i.e., balloon A). At the time of the first alignment inspection (before crimping), the inner diameter of the scaffold was larger than the fully inflated diameter of the balloon (for example, the scaffold diameter was about 109% to 116% of the fully inflated diameter of a balloon having a diameter of 3.0 mm to 3.2 mm), so there is a possibility that the scaffold may shift longitudinally (with respect to the balloon) while the scaffold is being crimped to the balloon size. Considering this possibility, the scaffold is removed from the crimper, and the alignment of the scaffold on the balloon with respect to the proximal and distal balloon markers is inspected.

[0189]

[0181] "Final Alignment Confirmation" Step: When it is necessary to adjust the scaffold on the balloon, the technician makes manual adjustments to move the scaffold to a predetermined position. However, it has been found that it is difficult to make these fine adjustments while the scaffold is placed on the fully inflated balloon and has an inner diameter slightly smaller than the outer diameter of the balloon. To address this need, the balloon pressure is slightly lowered or the balloon is temporarily deflated to make realignment easier. When the scaffold is properly realigned between the balloon markers, the scaffold and the fully inflated balloon are returned to the crimper. Since the inner diameter of the scaffold and the balloon size are approximately equal, the final crimping of the scaffold to the balloon of the catheter can be started. It is preferable to make the scaffold diameter slightly smaller than the fully inflated diameter of the balloon before the start of Stage III so that the scaffold does not move further longitudinally with respect to the balloon. As described above, when two balloons are used, balloon B is replaced with balloon A, alignment is performed with respect to balloon A, and the scaffold is crimped to the final diameter of balloon B.

[0190]

[0182] Stage III: Return the scaffold and balloon to the crimper. The jaw closes to approximately the same diameter as in Stage II, or slightly larger (taking into account the recoil that occurs during alignment inspection). Hold the crimper jaw at this diameter for a third dwell period, which may be the time required for the scaffold to return to the crimp temperature.

[0191]

[0183] Next, reduce the iris diameter to approximately equal to, or slightly smaller than, the OD of the balloon when the balloon is unpressurized and has randomly distributed folds. That is, crimp the scaffold to approximately the OD of the balloon when the balloon has been pressurized and then shrunk such that almost all of the preformed folds are replaced with random folds. For example, for a 3.5 mm scaffold, the iris diameter is reduced to approximately 1.78 mm. After this diameter reduction, the scaffold OD is approximately 60% of its diameter in Stage III and approximately 50% of its starting or pre-crimp OD.

[0192]

[0184] Stage IV: After reducing the scaffold OD to approximately 50% of its starting diameter, hold the crimper jaw at this diameter for a third dwell period. In a preferred embodiment, the balloon pressure decreases slightly during this dwell. For example, for a 3.0 mm semi-compliant PEBAX balloon, the pressure decreases from 70 psi to 50 psi during the Stage IV dwell. This decrease is preferred to achieve a lower cross-sectional profile and / or to protect the balloon material from overstretching.

[0193]

[0185] After the Stage IV dwell period, deflate the balloon, or return it to atmospheric pressure, and reduce the crimper iris to the final crimp OD, e.g., 1.01 mm or approximately 30% of its pre-crimp OD. This balloon deflation can be done by opening the valve that supplies pressurized gas to the balloon while the iris diameter is being reduced to the final crimp diameter or immediately prior thereto.

[0194]

[0186] Next, the jaws of the crimper are held at the crimp temperature (i.e., the scaffold temperature is between 15 degrees below TG and approximately TG) or without holding the crimp temperature for a rest period of about 170 seconds or held at the final crimp diameter over 100 - 200 seconds. This final rest period is intended to reduce the amount of scaffold rebound when removing the crimped scaffold from the crimper. Immediately after the 170 - second rest, the scaffold is removed and a retention sheath is placed over the scaffold to further reduce rebound. A leak test may be performed after the final stage of crimping.

[0195]

[0187] (As shown in the above example), it may be necessary to provide an auxiliary pressure source for the balloon to maintain a relatively constant pressure throughout the diameter reduction and rest period. In fact, in one embodiment, it was found that a pressure drop occurred in the balloon during diameter reduction. To address this pressure drop, a secondary pressure source was used to maintain the same pressure during diameter reduction as during the rest period.

[0196]

[0188] The foregoing example of a preferred crimping process that selectively pressurizes the balloon throughout the crimp step is expected to provide three advantages while minimizing possible over - stretching of the balloon. The first advantage is increased scaffold - balloon retention. By maintaining a relatively large pressure in the balloon throughout most of the crimp step, more balloon material will be pushed into the scaffold than if the crimp were performed without balloon pressurization or only after the diameter of the scaffold has been substantially reduced, because more balloon material should be placed between the struts of the scaffold. Additionally, by substantially removing the creases before diameter reduction, the balloon material is expected to become more compliant. Thus, more balloon material can extend between the struts rather than being pushed between the scaffold and the catheter shaft when the scaffold is being crimped.

[0197]

[0189] The second advantage of balloon pressurization is the more uniform expansion of the crimped scaffold as the balloon expands. If the balloon is initially inflated and there is maximum space available within the attached scaffold for the balloon to deploy before crimping occurs, the balloon material will be more uniformly disposed around the catheter shaft after crimping. In a preferred embodiment, the balloon is inflated completely and held in this inflated state for at least 10 seconds prior to crimping so that all pre - formed folds are reliably removed. If the balloon is inflated after the scaffold has been partially crimped (thus leaving little space available for the balloon to fully deploy), and the balloon is only partially expanded and the fold lines or balloon memory are not removed by the balloon pressure, then due to the presence of folds or partial folds, displacement or misalignment of the balloon material can occur during crimping, thereby resulting in a more non - uniform distribution of the balloon material around the catheter shaft after crimping.

[0198]

[0190] The third advantage is the avoidance of out - of - plane torsion or overlap of the scaffold struts, which can result in loss of strength, cracking or breakage of the struts. As described above, by supporting the scaffold within the crimper with an inflated balloon, it is believed that the tendency of the struts to deviate from alignment is suppressed or minimized.

[0199]

[0191] The aforementioned advantages can be achieved without the risk of excessive balloon material stretching in the crimping process where balloon pressure is selectively controlled. Referring to Figure 3B, the pressure range provided is 20 - 70 psi. The upper limit of this pressure range can form a fully inflated balloon and be maintained over the first three stages in the case of the balloon used in the example. Subsequently, in stage IV, the balloon pressure is reduced to 50 psi and 20 psi. Some tests have shown that by maintaining a constant and consistent fully inflated balloon pressure until the start of stage IV, or until the crimped scaffold reaches approximately 1 / 2 of the original scaffold diameter and then the pressure slightly decreases, a good balance of stent retention, uniform expansion, low cross - profile, uniform crimping, and avoidance of damage to the balloon material is provided.

[0200]

[0192] As described above, there are three possible methods for crimping. Two balloons, balloon A and balloon B, are used. Balloon B is used in the pre - crimp step (a), and balloon A (used with the introduction system) is used for the final crimp. Second, only one balloon (balloon A) is used throughout the crimping process including the alignment confirmation inspection. In this case, the scaffold inner diameter is larger than the fully inflated or over - inflated balloon A. Thus, misalignment can occur on the balloon before crimping. Third, only one balloon (balloon A) is used throughout the crimping process without a final alignment confirmation inspection. In this case, the balloon for the introduction system has a fully inflated or over - inflated state that is approximately equal to the inner diameter of the scaffold inner diameter. These different embodiments will be further described below.

[0201]

[0193] In some embodiments, the process is as described above by way of the example of FIGS. 17A - 17B, with the following exceptions. Two balloons are used. That is, in addition to the catheter balloon (balloon A), a sacrificial balloon or secondary balloon (balloon B) is used, rather than only balloon A as in the above example of the preferred embodiment. Balloon B has a nominal inflated balloon diameter larger than that of balloon A, or is a balloon that can be overinflated to a diameter larger than that of balloon A. Balloon B is used in stage I and stage II. Balloon B is selected to have a fully inflated diameter that is the same as or slightly larger than the original inner diameter of the scaffold. One advantage of this alternative embodiment is that (in contrast to the above example where there is a gap in stage I and balloon A provides little or no radial support to the scaffold) the scaffold is supported by the balloon through the crimping process. After stage II, the scaffold is removed from the crimper and balloon B is replaced with balloon A. Thereafter, the crimping process continues as described above.

[0202]

[0194] The above description of the illustrated embodiments of the present invention is not intended to be exhaustive, including what is described in the abstract, nor is it intended to limit the present invention to the forms disclosed. Specific embodiments of the present invention and examples thereof are described herein for purposes of illustration, but as will be understood by those skilled in the art, various modifications are possible within the scope of the present invention.

[0203]

[0195] These modifications can be made in light of the above detailed description of the present invention. The terms used in the claims should not be construed as limiting the present invention to only the specific embodiments disclosed herein.

Claims

1. The scaffold comprises a network of multiple rings interconnected by multiple links, each ring having multiple vertices including a U-shaped vertex and at least one of a Y-shaped or W-shaped vertex, and each ring extends circumferentially in a wavy manner along a vertical axis (B-B) perpendicular to the longitudinal axis (A-A). The proximal end includes the outermost proximal ring connected to the first proximal ring by a plurality of first proximal links, and the first proximal ring is connected to the second proximal ring by a plurality of second proximal links. The distal end includes the outermost distal ring connected to the first distal ring by a plurality of first distal links, and the first distal ring is connected to the second distal ring by a plurality of second distal links. The plurality of first proximal links or the plurality of first distal links include marker links having holes containing radiopaque markers, The marker link generally surrounds the hole and includes a periphery that defines the hole wall and the strut periphery, and the distance between the hole wall and the strut periphery is D. The radiopaque marker includes a head having a flange positioned on the periphery, The flange has a radial length of D / 2 to less than D, A medical device in which the thickness (t) of the scaffold and the length (L) between the anti-luminal side and the luminal side of the radiopaque marker are in a relationship of 1.1 ≤ (L / t) ≤ 1.

8.

2. The medical device according to claim 1, wherein the scaffold is configured to deliver a drug.

3. The medical device according to claim 2, further comprising a drug polymer coating disposed on the scaffold.

4. The medical device according to claim 1, wherein 1.1 ≤ (L / t) ≤ 1.

4.

5. The medical device according to claim 1 or 4, wherein L / t is approximately 1.

1.

6. The medical device according to claim 1 or 4, wherein L / t is approximately 1.

3.

7. The medical device according to claim 1, wherein the radiopaque marker has an overall height that is about 40% or less greater than the thickness t of the scaffold.

8. The medical device according to claim 1 or 7, wherein the radiopaque marker has an overall height that is about 10% to about 40% greater than the thickness t of the scaffold.

9. The medical device according to claim 1, wherein the thickness t of the scaffold is less than 125 microns.

10. The medical device according to claim 1 or 9, wherein the thickness t of the scaffold is less than 100 microns.

11. The medical device according to claim 1, wherein the scaffold is bioabsorbable.

12. The medical device according to claim 1 or 11, wherein the scaffold comprises poly(L-lactide) (PLLA).

13. The medical device according to claim 1, wherein the radiopaque marker further includes a deformed tip portion for fixing the radiopaque marker in the hole.

14. The medical device according to claim 1, wherein the hole has a first opening and a second opening, the first opening being larger than the second opening.

15. The medical device according to claim 1, wherein the marker link has an aspect ratio (AR) of about 4 to about 5, and the AR is obtained by dividing the maximum width of the marker link by the thickness of the marker link.

16. The medical device according to claim 1, further comprising a balloon catheter, wherein the scaffold is crimped to the balloon catheter.

17. The medical device according to claim 1, wherein the hole is a first hole, the marker link further has a second hole containing an additional radiopaque marker, and the first hole and the second hole are longitudinally aligned along the longitudinal axis.

18. The medical device according to claim 1, wherein the hole is a first hole, and the marker link further has a second hole containing an additional radiopaque marker, and the first hole and the second hole are circumferentially aligned along the vertical axis.

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