Medical devices to enhance fatigue resistance

Abstract

Example medical devices and methods of making example medical devices are disclosed. An example medical device includes a frame configured to be secured to cardiac tissue, wherein the frame includes a fatigue-resistant nickel-titanium alloy that is heat-set within a temperature range of 450-550 degrees Celsius.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 63 / 106162, filed on October 27, 2020, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to medical devices and methods for making medical devices. More particularly, the present disclosure relates to cardiovascular implants, including heart valve repair devices, and methods for making and using such devices. Background Art

[0004] A variety of medical devices have been developed to treat various cardiovascular diseases, such as heart valve repair devices, heart valve repair devices (e.g., annuloplasty rings), self-expanding stents, occlusive devices, cardiovascular filters (e.g., IVC filters), etc. Because medical devices placed in the heart must provide their therapeutic functions without interfering with or compromising other inherent functions, it may be desirable to have specific performance characteristics in the medical device. Many different structures and components for medical devices such as heart valves are known, each with certain advantages and disadvantages. However, there remains a need to provide alternative structures and components. Summary of the Invention

[0005] The present disclosure provides design, material, manufacturing method, and use alternatives for medical devices. An exemplary medical device includes a frame configured to be secured to cardiac tissue, wherein the frame comprises a fatigue-resistant nickel-titanium alloy that is heat-set within a temperature range of 450-550 degrees Celsius.

[0006] Alternatively or additionally to any of the embodiments above, wherein the frame is further processed by bending the frame through at least one pre-strain cycle.

[0007] Alternatively or additionally to any of the above embodiments, wherein the frame is further processed by heat setting the device at a temperature of 150-350 degrees Celsius for a period of at least 24 to 105 hours.

[0008] Alternatively or additionally to any of the above embodiments, wherein the frame is bent for 10-100 pre-strain cycles.

[0009] Alternatively or additionally to any of the above embodiments, wherein the frame bending occurs at a temperature of 50-75 degrees Celsius for 10-100 pre-strain cycles.

[0010] Alternatively or additionally to any of the above embodiments, the frame is further processed by heat setting the device at a temperature of 150-350 degrees Celsius for a period of at least 24 to 105 hours, and wherein the frame is further processed by bending the frame for at least one pre-strain cycle.

[0011] Alternatively or additionally to any of the above embodiments, the frame is further processed by bending the frame for 10-100 pre-strain cycles.

[0012] Alternatively or additionally to any of the above embodiments, the device is treated at a temperature between 150-350 degrees Celsius for a period of at least 24 to 105 hours such that the nickel titanium alloy has an R-phase when the frame is between 35-39 degrees Celsius.

[0013] Alternatively or additionally to any of the embodiments above, the medical device comprises an annuloplasty ring.

[0014] Another heart valve repair device includes a frame configured to be secured to heart tissue, wherein the frame includes a fatigue-resistant nickel-titanium alloy that is heat-set in a temperature range of 450-550 degrees Celsius, and wherein the frame is further processed by bending the frame at a temperature between 50-70 degrees Celsius for at least 10-100 pre-strain cycles.

[0015] Alternatively or additionally to any of the above embodiments, wherein the frame is further processed by heat setting the device at a temperature of 150-350 degrees Celsius for a period of at least 24 to 105 hours.

[0016] Alternatively or additionally to any of the above embodiments, the device is treated at a temperature between 150-350 degrees Celsius for a period of at least 24 to 105 hours such that the nickel-titanium alloy has an R-phase parent phase when the frame is between 35-39 degrees Celsius.

[0017] Alternatively or additionally to any of the above embodiments, wherein the frame bending occurs at a temperature of 50-75 degrees Celsius for 10 to 100 pre-strain cycles.

[0018] Alternatively or additionally to any of the above embodiments, wherein pre-straining by bending the frame at a temperature between 50-70 degrees Celsius for at least 10-100 cycles further comprises bending the frame at a strain amplitude between 6-12%.

[0019] Alternatively or additionally to any of the embodiments above, wherein the heart valve repair device comprises an annuloplasty ring.

[0020] An example method of forming a heart valve repair device may include forming a nickel titanium alloy into a fatigue resistant frame; and heat setting the nickel titanium frame at a temperature in the range of 450-550 degrees Celsius.

[0021] Alternatively or additionally to any of the above embodiments, further comprising bending the frame 10 to 100 pre-strain cycles.

[0022] Alternatively or additionally to any of the embodiments above, wherein bending the frame 10 to 100 pre-strain cycles further comprises bending the frame at a strain amplitude between 6-12%.

[0023] Alternatively or additionally to any of the above embodiments, further comprising heat setting the frame at a temperature of 150-350 degrees Celsius for a period of at least 24 to 105 hours.

[0024] Alternatively or additionally to any of the above embodiments, wherein heat setting the frame at a temperature of 150-350 degrees Celsius for a period of at least 24 to 105 hours includes the nickel titanium alloy having an R-phase when the frame is between 35-39 degrees Celsius.

[0025] The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following figures and detailed description more particularly exemplify these embodiments.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A more complete understanding of the present disclosure may be obtained from consideration of the following detailed description taken in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a perspective view of an exemplary heart valve repair implant including a frame, a collar, and an anchor;

[0029] Figure 2 yes Figure 1 A perspective view of a frame of an exemplary heart valve repair implant is shown;

[0030] Figure 3 yes Figure 2 Detailed view of a portion of the frame shown in .

[0031] While the present disclosure is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that it is not intended to limit the present disclosure to the particular embodiments described. On the contrary, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. Specific embodiments

[0032] For the following defined terms, these definitions shall apply, unless a different definition is given in the claims or elsewhere in this specification.

[0033] It is assumed herein that all numerical values ​​are modified by the term "about", whether or not explicitly stated. The term "about" generally refers to a range of numbers that one skilled in the art would consider equivalent to the stated value (e.g., having the same function or result). In many cases, the term "about" may include numbers that are rounded to the nearest significant figure.

[0034] The recitation of numerical ranges by endpoints includes all numbers within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0035] As used in this specification and the appended claims, the singular forms "a," "an," and "an" include plural references unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

[0036] Note that references in the specification to "an embodiment," "some embodiments," and "other embodiments" indicate that the described embodiments may include one or more particular features, structures, and / or characteristics. However, such a description does not necessarily mean that all embodiments include the particular features, structures, and / or characteristics. Furthermore, when particular features, structures, and / or characteristics are described in conjunction with one embodiment, it should be understood that, unless expressly stated otherwise, these features, structures, and / or characteristics may also be used in conjunction with other embodiments, whether or not expressly described.

[0037] The following detailed description should be read with reference to the drawings, in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily drawn to scale, depict illustrative embodiments and are not intended to limit the scope of the present disclosure.

[0038] The following description should be read with reference to the accompanying drawings, in which like reference numerals represent like elements throughout the several views. The accompanying drawings, which are not necessarily drawn to scale, depict illustrative embodiments of the claimed disclosure.

[0039] Furthermore, although discussed with specific reference to heart valve repair implants (eg, annuloplasty rings) in certain embodiments described herein, the present disclosure is applicable to a variety of medical devices adapted to be advanced through an opening or lumen into a patient's anatomy. For example, the present disclosure may be applied to heart valve replacement devices and components thereof, self-expanding stents, occlusive devices, cardiovascular filters (e.g., IVC filters, embolic protection filters), guidewires, pressure wires, implantable sensors (e.g., pulmonary artery sensors), cardiac occluders (e.g., atrial septal occluders, ventricular septal occluders, patent foramen ovale occluders, left atrial appendage occluders, paravalvular occluders, etc.), cardiac shunt devices, atrial flow regulators, neuromodulatory devices, fixed guidewire devices, various catheters (e.g., balloon, stent delivery, diagnostic, ablation, steerable, guided, ultrasound imaging, OCT, direct visualization, ureteral, biliary, retrieval balloon, direct injection needle catheters, etc.), drive shafts for rotational devices (e.g., atherectomy catheters and IVUS catheters), endoscopic devices, laparoscopic devices, embolic protection devices, spinal or cranial navigation devices, biopsy forceps, retrieval devices, and other such devices. In addition, the embodiments disclosed herein may be particularly applicable to any medical device having a nitinol component that is subject to cyclic loading. Furthermore, while some embodiments may be adapted or configured for use within a patient's vasculature, other embodiments may be adapted and / or configured for use in other anatomical structures. It will be appreciated that a wide variety of materials, sizes, and configurations may be used to construct suitable embodiments, depending on the desired properties. The following examples of some embodiments are included by way of example only and are not intended to be limiting.

[0040] The devices disclosed herein may include heart valve repair devices (e.g., an annuloplasty ring), and the medical device may include a frame. The annuloplasty ring, and particularly the frame (and its components), may include one or more materials that exhibit shape memory behavior, superelastic behavior, or both. These materials may be metal alloys, such as nitinol.

[0041] In general, certain Nitinol alloys can exhibit shape memory or superelastic (or pseudoelastic) properties, or both. Although Nitinol is essentially a binary alloy containing nickel and titanium, some superelastic and / or shape memory Nitinol alloys can contain additional elements such as cobalt, iron, chromium, niobium, palladium, copper, or vanadium. In addition, some other alloys exhibit shape memory or superelastic behavior, or, like some Ni:Ti alloys, both shape memory and superelasticity. Some examples of these alloys are: AgCd, AuCd, AuCu, CuAlNi, CuAuZn, CuSn, CuZn, CuZnSi, CuZnSn, CuZnAl, CuZnGa, CuZnXe, CuAlNi, InTl, NiAl, FePt, FePd, FeMn, Fe3Be, Fe3Pt, FeNiTiCo, and MnCu.

[0042] Superelasticity and shape memory are two different manifestations of reversible phase transformations. Superelasticity can be defined as the nonlinear, recoverable deformation behavior of nickel-titanium shape memory alloys at temperatures above the austenite finish temperature (Af). The nonlinear deformation results from the stress-induced formation of martensite during loading and the spontaneous reversion of this crystal structure to austenite during unloading. Shape memory alloys can be defined as metals that, after significant plastic deformation in the martensite phase, undergo thermoelastic changes in their crystal structure when heated above the austenite finish temperature, resulting in recovery of the deformation. Without being bound by the theory presented herein, these concepts are described in more detail below.

[0043] With respect to the linear elasticity of a material, it can be understood that when stress is applied to a linear elastic material at a relatively constant rate, the material's stress-strain curve may initially be linear until the material reaches its proportional limit. If further stress is applied to the material after this point, the material may undergo plastic deformation, such that when the stress is removed, the material may not return to its original shape and size. Thus, for a linear elastic material, the stress-strain curve appears as a substantially straight line within the proportional region (the portion of the curve before the proportional limit). Thus, when the material is stressed within this proportional region, the strain may increase proportionally, and when the stress is removed, the strain may decrease substantially along the same straight line, essentially returning to the origin of the stress-strain diagram.

[0044] In some cases, linear elastic nitinol can also be distinguished from superelastic nitinol, as linear elastic nitinol can accept strains up to approximately 2-5% while remaining essentially elastic (e.g., before plastic deformation), whereas superelastic nitinol can accept strains up to 8% before plastic deformation. Both materials can be distinguished from other linear elastic materials, such as stainless steel, which can only accept strains of approximately 0.09% to 1.1% before plastic deformation.

[0045] In some embodiments, the linear elastic nickel-titanium alloys do not exhibit any martensite / austenite phase transformation detectable by differential scanning calorimetry (DSC) and dynamic metallographic thermal analysis (DMTA) analysis over a wide temperature range. For example, in some embodiments, in the linear elastic nickel-titanium alloys, there may be no martensite / austenite phase transformation detectable by DSC and DMTA analysis over a wide temperature range of about -60 degrees Celsius (°C) to about 120°C. Thus, over this very wide temperature range, the mechanical properties of such materials are generally unaffected by temperature. In some embodiments, the mechanical properties of the linear elastic nickel-titanium alloys at ambient or room temperature are substantially the same as their mechanical properties at body temperature, for example, because they do not exhibit a superelastic plateau and / or signature region. In other words, over a wide temperature range, the linear elastic nickel-titanium alloys maintain their linear elastic properties and / or performance.

[0046] In some embodiments, the linear elastic nickel titanium alloy can be in the range of about 50% to about 60% nickel by weight, with the remainder being substantially titanium. In some embodiments, the composition is in the range of about 54% to about 57% nickel by weight.

[0047] However, it will be appreciated that in some embodiments, superelastic alloys (e.g., superelastic nickel-titanium alloys) may be used to achieve desired properties and performance characteristics. Specifically, in the case of superelastic metal alloys (SEMAs), the stress-strain curve may be nonlinear. This nonlinearity may be a product of phase transformations that occur within the alloy when it is stressed (in contrast to linear elastic materials, which typically do not have significant phase transformations within the elastic region). Some SEMAs may have two solid phases associated with superelasticity: an austenite phase and a martensite phase. The austenite phase may be the more ordered phase in these alloys, with limited deformation strain without phase transformation or plastic deformation. The martensite phase may be a lower-order phase that is more easily deformed through twinning. The changes between these phases are changes in the metal's crystal structure. Phase changes in these materials are typically caused by temperature changes or external mechanical forces. In some cases, in order to improve the in vivo performance and / or durability of the medical device, it may be necessary to construct the medical device based on a specific combination of heat treatment and / or pre-strain treatments. For example, in some examples described herein, specific heat treatment and pre-straining techniques may be utilized to construct one or more components of a heart valve repair device (eg, an annuloplasty ring). These mechanisms are discussed in greater detail below.

[0048] Figure 1An exemplary cardiac repair implant (e.g., annuloplasty ring) 10 is shown. Implant 100 can be designed to repair a leaking mitral valve. In particular, implant 100 can be implanted directly into the mitral valve annulus, whereby manipulation of implant 100 can draw the leaflets of the mitral valve together to reestablish proper mitral valve function.

[0049] Implant 100 can include a frame 12. Frame 12 can extend around and partially along a longitudinal axis 50. Axis 50 can be defined by frame 12. Frame 12 can be generally symmetrical with respect to axis 50. However, frame 12 need not be symmetrical with respect to axis 50. Frame 12 can be a generally circular shape around axis 50. However, this is not intended to be limiting. Instead, frame 12 can be circular, quasi-circular, elliptical, segmented, other shapes, or combinations thereof. Frame 12 can vary in shape, size, configuration, and the like.

[0050] Implant 100 may include one or more struts 14. Struts 14 may be elongated members of frame 12. In some examples, struts 14 and / or other components of frame 12 may be formed from a nickel-titanium alloy (e.g., Nitinol). In other examples, struts 14 and / or other portions of frame 12 may be formed from other metals, metal alloys, plastics, polymers, composite materials, other suitable materials, or combinations thereof. Additionally, Figure 1 The frame 12 is shown to include sixteen struts 14. However, in other examples, there may be fewer or more than sixteen struts 14. For example, in some embodiments, there may be at least two, four, six, eight, ten, twelve, fourteen, eighteen, twenty, twenty-two, twenty-four, twenty-six, twenty-eight, thirty, or more struts 14.

[0051] In some examples, the pillar 14 can be made of a single piece of material. However, in other embodiments, the pillar 14 can be a separate component that is detachably connected together by other components of the implant 100. For example, the pillar 14 can be held together by various components described herein, such as the collar 18, the anchor 16, other components, or a combination thereof. In some embodiments, the pillar 14 can be attached by a hinge, a pin, or other suitable means.

[0052] like Figure 1 As shown, the elongated mid-portion of the strut 14 can have a generally rectangular cross-section, but can vary in circumferential width and radial thickness to allow for different beam properties and forces applied when the collar is manipulated. Unless otherwise specified, "perimeter" as used herein generally refers to a circumference or boundary, and can also refer to a circle or other circular or non-circular path lying within a plane substantially perpendicular to the axis. In some embodiments, other configurations and / or cross-sectional shapes of the strut 14 can be implemented.

[0053] Figure 2 Shown Figure 1 The frame 12 of the implant 100 shown in FIG. 1 (eg, for simplicity, Figure 1 The collar 18 and anchor 16 are shown having been removed from the implant 100. Figure 2 Only the bare frame 12 is left). Figure 2 The struts 14 are shown to extend about an axis 50 to form various shapes of the frame 12. The struts 14 can be arranged so that the wall pattern of the frame 12 can be generally sinusoidal or zigzag. In some embodiments, the wall pattern can have other suitable shapes, sinusoidal or otherwise. The apex of the sinusoidal frame 12 can be pointed or rounded.

[0054] Figure 2 As shown, in some examples, pairs of adjacent struts 14 can meet at vertices. For example, at least a first pair of adjacent struts 14 can meet at upper vertices or crowns 15. At least a second pair of adjacent struts 14 can meet at lower vertices or crowns 17. The upper crowns 15 and lower crowns 17 are sequentially spaced along the circumference of the frame 12, with one of the upper crowns 15 followed by one of the lower crowns 17, then another of the upper crowns 15, and so on. In the embodiment shown, there are eight upper crowns 15 and eight lower crowns 17.

[0055] Return Reference Figure 1 Each upper crown 15 can be configured to have a collar 18 mounted on and / or around the upper crown 15. Thus, as described herein, the upper crown 15 can include various features, dimensions, etc. for coupling with the collar 18, as further described. Figure 1 18. In some embodiments, one or more of the upper crown portions 15 may not include a collar 18. In some embodiments, less than all of the upper crown portions 15 may be configured to receive a collar 18. In some embodiments, all of the upper crown portions 15 may be configured to receive a collar 18.

[0056] Figure 1 It is further shown that one or more of the lower crowns 17 can be coupled to an anchor 16. Each anchor 16 can be movably coupled to a lower crown 17. The anchors 16 can engage tissue of the heart, such as the mitral annulus, to secure the implant 100 to the annular tissue. Movement of the anchors 16 relative to the lower crowns 17 can cause the anchors 16 to penetrate the annular tissue. The lower crowns 17 can include various engagement features, such as flanges and / or openings, to allow for such movement of the anchors 16.

[0057] The struts 14 can be reconfigured about the upper crown 15 and the lower crown 17. Pairs of adjacent struts 14 that meet at the upper and lower crowns 15, 17 can be angularly moved relative to each other. This movement can be described as rotation or pivoting of the adjacent struts 14 about the respective upper or lower crowns 15, 17. For example, two adjacent struts 14 forming the upper crown 15 can be moved so that the struts 14 effectively rotate relative to each other about the upper crown 15. For example, two adjacent struts 14 forming the lower crown 17 can be moved so that the struts 14 effectively rotate relative to each other about the lower crown 17. This "rotation" of the struts 14 can include clamping the struts 14 together, such as by the collars 18 described herein. Thus, the adjacent struts 14 may not include actual rotatable hinges, pins, or other rotating features. Movement of the struts 14 closer together to reduce the angle between them is described as "closing" the struts 14. Movement of the struts 14 further apart to increase the angle between them is described as "opening" the struts 14.

[0058] In the absence of external force applied to the pillars 14, the pillars 14 can be biased to an amplified cross-sectional configuration. External circumferential compressive force is applied to the pillars 14, for example, by means of collars 18, so that the pillars 14 can be moved angularly, for example closed. In the case of a circular implant 100, the movement of the pillars 14 in such a closed manner may also cause the implant 100 to reduce its circumference (for example, diameter). In its unconstrained state, the framework 12 can be in an amplified configuration. The circumferential force applied to the compression can cause the circumference of the framework 12 to decrease. The removal or reduction of the circumferential force can allow the framework 12 to open. The circumferential force can be increased or decreased by further moving the collars 18 downward or upward in the axial direction, respectively. The collars 18 can be locked in place after axially translating the upper crown 15 downward to fix the implant 100 at a specific width.

[0059] As mentioned above, the implant 10 includes one or more restraining devices, such as collars 18. Figure 1 As shown, the implant 10 can include eight collars 18. In some embodiments, there can be fewer or more than eight collars 18. The number of collars 18 can correspond to the number of upper crowns 15. In some embodiments, there can be fewer collars 18 than upper crowns 15. Thus, in some embodiments, some upper crowns 15 of the frame 12 may not include collars 18.

[0060] The collar 18 can be coupled to the corresponding upper crown 15. The collar 18 can be assembled on the upper crown 15. The collar 18 forms an inner opening at least partially therethrough, and when the collar 18 is assembled on the upper crown 15. In some embodiments, the collar 18 can be circular, rectangular, square, triangular, segmented, polygonal, other suitable shapes, or combinations thereof. Figure 1As shown, the collar 18 can at least partially surround the corresponding upper crown portion 15. As shown, the collar 18 completely surrounds the corresponding upper crown portion 15. In some embodiments, the collar 18 may not completely surround the upper crown portion 15. The collar 18 is engaged with the upper crown portion 15.

[0061] Collar 18 can engage upper crown 15 and be advanced downwardly over upper crown 15 to angularly move a corresponding pair of adjacent struts 14 toward each other. Collar 18 can apply a compressive circumferential force to struts 14, causing struts 14 to reduce the angle between them. The circumferential force can be applied inwardly to struts 14 and toward upper crown 15. Thus, a vertical force applied to collar 18 can be converted into a circumferential force on struts 14. "Circumferential" means that the force is directed along the periphery or boundary of frame 12, as viewed from the top or bottom of frame 12, rather than constraining frame 12 to a circular shape. Movement of collar 18 over struts 14 moves (e.g., rotates) struts 14, reducing the angle between adjacent struts 14. A first circumferential force can be applied to one of struts 14 via collar 18, and a second circumferential force, directional opposite to the first circumferential force, can be applied to the adjacent strut 14 via the same collar 18. The further the collar 18 moves down the post 14, the more the post 14 moves and the more the angle decreases, causing the width (e.g., diameter) of the frame 12 to decrease. Thus, due to the movement of the collar 18, the posts 14 move relative to each other around the upper crown 15. The collar 18 can be locked in place, for example, by a locking tab 19.

[0062] like Figure 1As shown, the implant 10 may include one or more anchors 16. The anchors 16 may be made of a suitable biocompatible metal alloy, such as stainless steel, cobalt chromium, platinum iridium, nickel titanium, other suitable materials, or combinations thereof. Each anchor 16 may be sharpened at its distal point or leading turn to facilitate penetration into cardiac tissue. The total axial length of each anchor 16 may be from about 10 mm to about 15 mm (mm). In some embodiments, the total axial length of the anchor 16 may be shorter or longer than 10 to 15 mm (mm). By "total" axial length, we mean the axial length of the anchor 16 from the end of the distal penetrating tip to the relatively proximal end of the head. The axial length (i.e., in the axial direction) of the helical portion of the anchor 16 may be from about 6 mm to about 12 mm (mm). In some embodiments, the axial length of the helical portion of the anchor 16 may be shorter or longer than 6 to 12 mm (mm). The anchor 16 may be capable of extending axially beyond the corresponding lower crown 17 by about 4 mm to about 7 mm (mm). For example, the helical portion of the anchor 16 can extend from about 4 millimeters to about 7 millimeters (mm) into the heart tissue. As previously described, the frame 12 is shown as having eight upper crowns 14, eight lower crowns 16, and anchors 16, but this number of vertices is shown for illustrative purposes only and can vary, such as four upper and lower vertices, sixteen upper or lower vertices, etc. In some embodiments, regardless of the number of vertices, each upper crown 15 is fitted with a collar 18, and each lower crown 17 has a corresponding anchor 16 threadedly received through an opening of the anchor 16.

[0063] As described above, manipulation of the one or more collars 18 can tighten the implant 10, causing the implant 10 to decrease in size, thereby pulling the leaflets of the mitral valve closer together. However, it will be further appreciated that once the implant 10 is positioned along the mitral valve, the size and shape of the implant 10 may undergo significant dynamic changes as the heart transitions during a single cardiac cycle. Furthermore, the implant 10 will undergo dynamic changes during its lifetime, and therefore, the implant 10 needs to be designed to withstand the extended stresses associated with cyclic loading.

[0064] For example, Figure 3 A portion of the above-mentioned frame 12 is shown. In particular, Figure 3 The bent portion 20 of the support column 14 of the frame 12 is shown. Figure 3As shown, the bent portion 20 of pillar 14 can be generally defined as the part of the framework 12 that the bottom of collar 18 can rest along pillar 14.It is understandable that when implant 10 is tightened (by the rotation of one or more collars 18), bent portion 20 can be repeatedly bent, thereby withstand cyclic stress during the life of implant 10.It is understandable that it may be beneficial to construct implant 10 (or its part, for example bent portion 20) by the material that is designed to withstand significant cyclic load.As discussed in more detail below, one or more parts of implant 10 (for example, framework 12 or any part thereof, for example bent portion 20) can be made of specific processing method and parameter, include but not limited to heat treatment and / or pre-strain treatment.

[0065] The present disclosure may be further clarified by reference to the following examples, which are provided to illustrate some embodiments and are not intended to limit the present disclosure in any way.

[0066] Example 1 – Example of a nominal manufacturing process for a Nitinol implant

[0067] An example nominal process for manufacturing a medical device including the heart valve repair device 10 disclosed herein (e.g., an annuloplasty ring) may include:

[0068] Step 1 - Example A Nitinol sample (e.g., frame 12) can be heat set at an initial temperature of 450-550 degrees Celsius for 5-20 minutes. The heat setting process can be designed to bend the Nitinol sample through multiple heating / cooling cycles to achieve a specific geometry within the sample. Additional heat exposure steps can be added to adjust the austenite finish temperature or other mechanical properties of the Nitinol sample. In some cases, the final austenite finish temperature is typically between 15 degrees Celsius and 32 degrees Celsius.

[0069] After the initial heat setting step (eg, step 1 above), a thermomechanical fatigue test can be performed, which can include cyclically loading the Nitinol sample under specific load parameters. The following paragraphs provide a general description of an example thermomechanical fatigue test performed on a Nitinol sample.

[0070] The fatigue analysis may initially include performing a finite element analysis (FEA) on the first Nitinol sample, which estimates the strain value of the sample displacement in a conventional cantilever test. The test may initially begin with a relatively small displacement of the sample, subjecting the sample to a predetermined number of displacement cycles (e.g., 10,000 cycles at a given amplitude). If the sample withstands the initial cyclic load, the cantilever test may be repeated on the same sample with successively higher amplitudes until the sample fractures. After the first sample fractures, the same fatigue test may be performed on additional Nitinol samples using the same cyclic load parameters and displacement sequence as the initial sample. Each sample may be cycled to failure, and the corresponding displacement at fracture of each sample may be determined. Then, using the fracture displacement data for the entire set of samples, a "mean displacement at fracture" value may be calculated. Finally, a finite element analysis may be performed, which may determine the strain value corresponding to the average fracture displacement value determined from the entire set of Nitinol samples tested. This strain value may be described as "% alternating strain."

[0071] Thermomechanical fatigue testing (as described above in this example) following the initial heat setting step (as described above in this example) showed an average fatigue strength for the Nitinol samples at 0.498% alternating strain.

[0072] Example 2 – Example of a pre-strained nominal process for manufacturing a Nitinol implant

[0073] An example nominal process with another pre-straining step for manufacturing a medical device including the heart valve repair device 10 disclosed herein (e.g., annuloplasty ring) may include:

[0074] Step 1 - Example A Nitinol sample (eg, annuloplasty frame 12) can be heat set at an initial temperature of 450°F-550°F for 5-20 minutes.

[0075] Step 2 - Pre-strain the Nitinol sample, either mechanically or otherwise, to stretch the Nitinol sample beyond its designed in vivo conditions. This pre-straining step may induce retained martensite and / or plastic deformation within the sample. In some examples, the sample may be pre-strained for 1 to 100 cycles. In certain examples, the sample may be pre-strained at a strain amplitude of 4 to 16%.

[0076] After completing the above-described processing steps, fatigue testing (as described in relation to Example 1) can be performed. Fatigue testing results for the nominal process (described above in relation to Example 1) with an additional pre-straining step (as described above in this embodiment) can show an average fatigue strength of the Nitinol samples at an alternating strain of 0.822%. This represents a 65% increase over the nominal process (e.g., 0.822% versus 0.498% alternating strain).

[0077] Example 3 - R-Phase Process Nominal Process Example for Manufacturing Nitinol Implants

[0078] An example nominal process with R-phase processing steps for manufacturing a medical device including the heart valve repair device 10 disclosed herein (e.g., annuloplasty ring) may include:

[0079] Step 1 - Example A Nitinol sample (eg, annuloplasty frame 12) can be heat set at an initial temperature of 450°F-550°F for 5-20 minutes.

[0080] Step 2 - Heat setting the Nitinol implant to form the R-phase. The R-phase treatment may involve heat setting the sample at 150 degrees Celsius to 350 degrees Celsius for 6 to 720 hours after achieving final shape setting.

[0081] After completing the above-described processing steps, fatigue testing (described above with respect to Example 1) can be performed. Fatigue test results for the nominal process (described above with respect to Example 1) with R-phase treatment (described above in this embodiment) can show an average fatigue strength of the samples at an alternating strain of 0.761%. This represents a 53% increase over the nominal process (e.g., 0.761% versus 0.498% alternating strain).

[0082] Example 4 - Example of a nominal process for pre-straining and R-phase treatment of Nitinol implant fabrication

[0083] An example nominal process with R-phase processing steps for manufacturing a medical device including the heart valve repair device 10 disclosed herein (e.g., annuloplasty ring) may include:

[0084] Step 1 - Example A Nitinol sample (eg, annuloplasty frame 12) can be heat set at an initial temperature of 450°F-550°F for 5-20 minutes.

[0085] Step 2 - Heat setting the Nitinol implant to form the R-phase. The R-phase treatment may involve heat setting the implant at 150°C to 350°C for 6-720 hours after achieving final shape set.

[0086] Step 3 - Pre-strain the Nitinol sample for 1 to 100 cycles. In some examples, the pre-straining of the sample may be performed at a strain amplitude of 4 to 16%.

[0087] Treating Nitinol implants with R-phase treatment and pre-strain treatment can change the dislocation density and microstructure of the implant and increase the fatigue resistance of the device.

[0088] After completing the above-described processing steps, fatigue testing (as described above with respect to Example 1) can be performed. The fatigue test results of the nominal process with R-phase treatment and pre-strain treatment may show that the average fatigue strength of the samples is 1.48% alternating strain. This represents a percentage increase of 197% over the nominal process (e.g., 1.48% vs. 0.498% alternating strain).

[0089] The materials that can be used for the various components of the medical device 10 may include materials commonly associated with medical devices. For simplicity, the following discussion refers to the implant 10 and other components of the implant 10. However, this is not intended to limit the devices and methods described herein, as the discussion can be applied to other medical devices disclosed herein.

[0090] The medical device 10 and / or other components of the medical device 10 can be made of metals, metal alloys, polymers (some examples of which are disclosed below), metal polymer composites, ceramics, combinations thereof, or other suitable materials. Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, such as available from DuPont), and polyoxymethylene (POM). ), polyether block esters, polyurethanes (e.g., polyurethane 85A), polypropylene (PP), polyvinyl chloride (PVC), polyether esters (e.g., available from DSM Engineering Plastics ), ether or ester based copolymers (e.g., butene / poly(alkylene ether) phthalate and / or other polyester elastomers such as those available from DuPont ), polyamides (e.g., from Bayer or from Elf Atochem ), elastic polyamides, block polyamide / ether, polyether block amide (PEBA, for example under the trade name obtained), ethylene vinyl acetate copolymer (EVA), silicone, polyethylene (PE), high-density polyethylene, low-density polyethylene, linear low-density polyethylene (e.g. ), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polyterephthalamide (e.g. ), polysulfone, nylon, nylon-12 (e.g., available from EMS American Grilon ), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefins, polystyrene, epoxy resins, polyvinylidene chloride (PVdC), poly(styrene-b-isobutane-e-styrene) (e.g., SIBS and / or SIBS50A), polycarbonate, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers, polymer / metal composites thereof, etc. In some embodiments, the sheath can be blended with a liquid crystal polymer (LCP). For example, the blend can contain up to about 6% LCP.

[0091] Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel titanium alloys, such as linear elastic and / or superelastic nitinol; other nickel alloys, such as nickel chromium molybdenum alloys (e.g., UNS: N06625, such as UNS:N06022, such as UNS:N10276, such as HASTELLOYTM other alloys, etc.), nickel-copper alloys (e.g., UNS: NO4400, such as etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035, such as etc.), nickel-molybdenum alloys (such as UNS: N10665, such as ), other nickel-chromium alloys, other nickel-molybdenum alloys, other cobalt-nickel alloys, other nickel-iron alloys, other copper-nickel alloys, other nickel-tungsten or tungsten alloys, etc., cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (such as UNS: R30003, such as etc.); platinum-rich stainless steel; titanium; combinations thereof; etc.; or any other suitable material.

[0092] In at least some embodiments, part or all of the medical device 10 may also be doped, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials that are capable of producing a relatively bright image on a fluorescent screen or other imaging technology during a medical procedure. This relatively bright image helps the user of the medical device 10 determine its location. Some examples of radiopaque materials may include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloys, polymer materials loaded with radiopaque fillers, and the like. In addition, other radiopaque marker bands and / or coils may also be incorporated into the design of the implant 10 to achieve the same result.

[0093] In some embodiments, a degree of magnetic resonance imaging (MRI) compatibility is imparted to the implant 10. For example, the medical device 10 or portions thereof can be made of a material that does not substantially distort the image and produce substantial artifacts (e.g., gaps in the image). For example, certain ferromagnetic materials may not be suitable because they may produce artifacts in MRI images. The implant 10 or portions thereof can also be made of a material that can be imaged by an MRI machine. Some materials that exhibit these properties include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003, such as etc.), nickel-cobalt-chromium-molybdenum-aluminum alloys (e.g. UNS: R30035, etc.), Nitinol, etc.

[0094] It should be understood that the present disclosure is in many respects illustrative only. Changes may be made in detail, particularly in shape, size, and arrangement of steps, without exceeding the scope of the present disclosure. This may include, within appropriate limits, the use of any feature of one example embodiment in other embodiments. Of course, the scope of the present disclosure is defined in the language used by the appended claims.

Claims

1. A medical device comprising: A frame configured to be secured to cardiac tissue, wherein the frame comprises a fatigue-resistant nickel-titanium alloy that is heat-set at a temperature in the range of 450-550 degrees Celsius, wherein the frame is further processed by heat-setting the device at a temperature of 150-350 degrees Celsius for a period of 24 hours to 105 hours.

2. The medical device according to claim 1, wherein The frame is further processed by bending the frame through at least one pre-strain cycle.

3. The medical device of claim 2, wherein the frame is bent for 10-100 pre-strain cycles.

4. The medical device according to claim 3, wherein The frame is bent for 10 to 100 pre-strain cycles at a temperature of 50-75 degrees Celsius.

5. The medical device according to any one of claims 1 to 4, wherein: The device is processed at a temperature of 150-350 degrees Celsius for a period of 24 hours to 105 hours such that the nickel-titanium alloy has an R-phase parent phase when the frame is at a temperature of 35-39 degrees Celsius.

6. The medical device of any one of claims 1-4, wherein the medical device comprises an annuloplasty ring.

7. A heart valve repair device comprising: A frame configured to be secured to cardiac tissue, wherein the frame comprises a fatigue-resistant nickel-titanium alloy that is heat-set at a temperature in the range of 450-550 degrees Celsius, wherein the frame is further processed by heat-setting the device at a temperature of 150 to 350 degrees Celsius for a period of 24 to 105 hours, and wherein the frame is further processed by bending the frame at a temperature of 50–70 degrees Celsius for 10-100 pre-strain cycles.

8. The heart valve repair device according to claim 7, wherein: The device is processed at a temperature of 150-350 degrees Celsius for a period of 24 to 105 hours such that the nickel-titanium alloy has an R-phase when the frame is at a temperature of 35-39 degrees Celsius.

9. The heart valve repair device according to any one of claims 7-8, wherein: Bending the frame for 10-100 pre-strain cycles at a temperature of 50-70 degrees Celsius further includes bending the frame at a strain amplitude between 6-12%.

10. The heart valve repair device according to any one of claims 7-8, wherein the heart valve repair device comprises an annuloplasty ring.

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