Multi-row deploy zone constraining devices and methods

Abstract

To provide a delivery system with a removable constraint.SOLUTION: A delivery system includes a catheter with a removable constraint. The removable constraint is a knit tubular construct. The removable constraint can be used, for example, to constrain a medical device to a delivery configuration. The removable constraint may include one or more fibers or strands arranged about the device to maintain the device in a constrained or delivery configuration.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Provisional Application No. 63 / 039,834, filed June 16, 2020, which is incorporated by reference in its entirety for all purposes.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to apparatus, systems and methods for delivery of implantable medical devices. More specifically, the present disclosure relates to apparatus, systems and methods including covers for implantable medical devices during device delivery. [Background technology]

[0003] Minimally invasive delivery techniques for implantable medical devices offer various advantages, such as reduced trauma, risk of infection, and recovery time. Examples of implantable medical devices include stents and stent grafts that are utilized to radially support, treat, and / or otherwise augment tubular passageways within the body, including arteries, veins, airways, gastrointestinal tracts, and biliary tracts. Additional examples of implantable medical devices include prosthetic valves (e.g., prosthetic heart valves). Transcatheter delivery is a technique for delivering such implantable medical devices, where the medical device to be delivered begins in a diametrically compressed state for delivery and is then expanded (e.g., self-expanding or manually expandable) at the treatment site within the patient's body.

[0004] Stents, stent grafts, prosthetic valves, filters and other implantable objects may be deployed by plastically deforming (e.g., using an inflatable balloon) or by allowing them to expand, self-expand and elastically recover to a deployed diameter from a collapsed or constrained delivery diameter.

[0005] For example, U.S. Patent No. 6,224,627, filed June 15, 1998 and entitled "Remotely Removable Covers and Supports," describes, among other things, a thin, tubular, multifilament (film or fiber) structure capable of holding high internal pressure. When desired, the filament extensions can be pulled in any direction to expand the structure. This structure can be useful in self-expanding stent or stent graft delivery systems, balloon dilatation catheters, removable guidewire lumens for catheters, drug infusion or aspiration catheters, guidewire bundle casings, removable filters, removable wire insulation, removable packaging, and other applications. Summary of the Invention

[0006] According to one example ("Example 1"), a knitted tubular structure includes a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

[0007] According to another example ("Example 2"), in addition to the device of Example 1, corresponding knits within each of the at least two knit rows are configured to release substantially simultaneously as the at least two knit rows gradually release along the longitudinal length of the body.

[0008] According to another example ("Example 3"), in addition to Examples 1 or 2, a first fiber of the plurality of fibers defines a chain knit within one of the at least two knit rows.

[0009] According to another example ("Example 4"), in addition to Example 3, the plurality of knits form a first knit row, a second knit row, and a third knit row, and the first fiber interacts with each of the first knit row, the second knit row, and the third knit row along the longitudinal length of the body.

[0010] According to another example ("Example 5"), in addition to Example 4, second fibers of the plurality of fibers alternate between the first knit row and the second knit row along the longitudinal length of the body.

[0011] According to another example ("Example 6"), further to Examples 1 or 2, the plurality of fibers includes a first fiber, a second fiber, a third fiber, and a fourth fiber, each of the first fiber, the second fiber, the third fiber, and the fourth fiber defining a corresponding chain knit.

[0012] According to another example ("Example 7"), in addition to Example 6, the at least two knit rows include a first knit row, a second knit row, a third knit row, and a fourth knit row, the first fiber and the second fiber define corresponding chain knits in the first knit row, and the third fiber and the fourth fiber define corresponding chain knits in the third knit row.

[0013] According to another example ("Example 8"), in addition to Example 7, the fiber interacts with the second fiber in the first knit row, with the third fiber in the second knit row, and with a fourth fiber in the fourth knit row.

[0014] According to another example ("Example 9"), in addition to any of the examples above, the plurality of knit rows are spaced laterally around a surface of the body.

[0015] According to another example ("Example 10"), in addition to any of the examples above, the plurality of fibers each have a diameter of less than 0.0060 inches.

[0016] According to another example ("Example 11"), a medical device includes an expandable member configured to expand radially from a first diameter to a second diameter, and a knitted tubular structure configured to radially releasably constrain the expandable member, the knitted tubular structure including a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

[0017] According to another example ("Example 12"), in addition to Example 11, the knitted tubular structure includes a first knit row, a second knit row, and a third knit row, the plurality of fibers of the knitted tubular structure include coordinating fibers and actuating fibers, the coordinating fibers form at least a portion of the knit in the first, second, and third knit rows, and the actuating fibers form at least a portion of the knit in only two of the first, second, and third knit rows.

[0018] According to another example ("Example 13"), in addition to Example 12, the knitted tubular structure includes at least two cooperating fibers.

[0019] According to another example ("Example 14"), in addition to Example 12, the knitted tubular structure includes a first knit row, a second knit row, a third knit row, and a fourth knit row, and the plurality of fibers of the knitted tubular structure include coordinating fibers, and the coordinating fibers form at least a portion of the knit in at least three of the first, second, third, and fourth knit rows.

[0020] According to another example ("Example 15"), in addition to Example 14, the cooperating fibers form a chain knit in at least one of the first, second, third and fourth knit rows.

[0021] According to another example ("Example 16"), in addition to Example 15, the plurality of fibers includes a plurality of cooperating fibers.

[0022] According to another example ("Example 17"), further to Examples 12-16, the cooperating fibers are operable to increase resistance to deployment when the knit rows are not deployed substantially simultaneously.

[0023] According to another example ("Example 18"), further to Examples 12-17, the cooperating fibers are operable to increase the maximum restraining force of the knitted tubular structure.

[0024] According to another example ("Example 19"), further to examples 11-18, at least two rows of knit of the knitted tubular structure are operable to release substantially simultaneously longitudinally along the body.

[0025] According to another example ("Example 20"), a method of deploying a medical device includes placing an expandable member within a patient, where the expandable member is constrained in a compressed configuration by a knitted tubular structure, the knitted tubular structure including a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body, the plurality of fibers including a deployment portion, holding a deployment portion of the plurality of fibers away from the expandable medical device, and applying a sufficient force to the deployment portion of the plurality of fibers to release at least a portion of the knit row.

[0026] According to another example ("Example 21"), a method of manufacturing a medical device includes radially compressing an expandable member into a compressed profile, providing a knitted tubular structure around the expandable member to constrain the expandable member in the compressed profile, where the knitted tubular structure includes a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

[0027] The foregoing examples are merely illustrative and should not be read to limit or narrow the scope of any of the inventive concepts otherwise provided by this disclosure. While multiple examples have been disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Accordingly, the drawings and detailed description should be regarded as illustrative in nature and not as restrictive in nature. [Brief description of the drawings]

[0028] The accompanying drawings are included to provide a further understanding of the disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the description, serve to explain the principles of the disclosure.

[0029] [Figure 1] FIG. 1 is a delivery system having a removable restraint and an expandable member, according to one embodiment.

[0030] [Diagram 2] FIG. 2 shows a removable restraint placed around an expandable device, according to one embodiment.

[0031] [Diagram 3] FIG. 3 is a removable restraint including three knit rows and various knits according to one embodiment.

[0032] [Figure 4] FIG. 4 is a knit pattern implemented for a removable restraint as shown in FIG. 3 according to one embodiment.

[0033] [Diagram 5] FIG. 5 is a removable restraint including four knit rows and various knits according to one embodiment.

[0034] [Figure 6] FIG. 6 is a knit pattern implemented for a removable restraint as shown in FIG. 5 according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Definitions and Terminology This disclosure is not intended to be read in a limiting sense, for example, the terms used in this application should be read broadly in relation to the meaning ascribed to such terms in the art.

[0036] With respect to the term imprecision, the terms "about" and "approximately" may be used interchangeably to refer to measurements that include the stated measurement and also include any measurement that is reasonably close to the stated measurement. A measurement that is reasonably close to the stated measurement deviates from the stated measurement by a reasonably small amount, as understood and readily ascertained by one of ordinary skill in the relevant art. Such deviations may result from measurement errors, differences in calibration of measuring and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning made to optimize performance and / or construction parameters considering differences in measurements related to other components, specific implementation scenarios, imprecise adjustment and / or manipulation of objects by humans or machines, and the like. In cases where it is determined that such reasonably small difference values ​​cannot be readily ascertained by one of ordinary skill in the relevant art, the terms "about" and "approximately" may be understood to mean plus or minus 10% of the stated value.

[0037] For reference, the term "circumference" is not meant to imply a circular cross-section, but instead should be understood broadly to refer to the exterior surface, outer dimensions or perimeter of a removable restraint.

[0038] Description of Various Embodiments Those skilled in the art will readily appreciate that the various aspects of the present disclosure may be implemented by any number of methods and devices configured to perform the intended functions. It should also be noted that the accompanying drawings referenced herein are not necessarily drawn to scale and may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawings should not be construed as limiting.

[0039] The system shown in FIG. 1 is provided as an example of various features of the system, and while combinations of these illustrated features are clearly within the scope of the present invention, the examples and the illustrations are not intended to suggest that the inventive concepts provided herein are limited to one or more of those features illustrated in the illustrations, from fewer, additional, or alternative features. FIG. 1 is a plan view of a delivery system 100 including a catheter 102 having a removable restraint 104, according to some embodiments. In some embodiments, the removable restraint 104 is a knitted tubular structure. As shown in FIG. 1, the removable restraint 104 is configured to restrain an implantable medical device 106 in a delivery configuration. The removable restraint 104 can include one or more fibers or strands 108 disposed about the device 106 to maintain the device 106 and the removable restraint 104 in a restrained or delivery configuration. The catheter 102 can include various ports, such as a first port 112, a second port 114, and a third port 116. One or more of ports 112, 114, 116 may be configured to provide access to one or more features (eg, a lumen) or to operate one or more functions (eg, restraint release), as desired.

[0040] The removable restraint 104 is disposed along the length of the device 106. The removable restraint 104 can also be disposed around the device 106 to substantially cover the device 106 for delivery. The one or more strands 108 can be disposed within a lumen (not shown) of the catheter 102 and can extend toward a proximal end of the catheter 102, which can also be disposed external to the patient during delivery of the device 106. The one or more strands 108 can include a proximal end 110 that can be tensioned by a user to release the removable restraint 104 and deploy the device 106. For example, the one or more strands can be accessible through one or more ports 112, 114, 116.

[0041] In certain instances, the one or more strands 108 release such that the interlocking portions (e.g., overlapping fibers or knits) release continuously and gradually along the length of the device 106. As described in more detail below, the removable restraint 104 is formed by interlocking one or more strands together that extend around the device 106. The one or more strands 108 can form a knit row 130 in which the one or more strands 108 interact with one another. The configuration of the knit row 130 and the one or more strands 108 that form the knit row 130 provides certain properties that facilitate restraint of the device 106 in a restrained configuration and release or deployment of the device from the removable restraint 104 to a deployed configuration. In some embodiments, the device 106 can be a stent, stent graft, balloon, prosthetic valve, filter, anastomosis device, occluder, or similar device.

[0042] 2 is a side view of a device 106 including a removable constraint 104, according to one embodiment. The device 106 is configured to transition from a delivery diameter D1 to a deployed diameter D2 (not shown) that is larger than the delivery diameter D1. In various examples, the removable constraint 104 is disposed about the device 106 at the delivery diameter D1. When the removable constraint 104 is removed from the device 106, the device is expandable (e.g., by self-expansion and / or forced expansion, such as balloon expansion) to the deployed diameter D2. The deployed diameter D2 is larger than the delivery diameter D1. In some embodiments, the deployed diameter D2 is the diameter of the device 106 when unconstrained. In other embodiments, the deployed diameter D2 is the diameter of the device 106 when the device 106 is delivered to the target site and engages the lumen wall at the target site.

[0043] The device 106 can have a desired deployed diameter D2 of, for example, about 5 mm to 15 mm, or 6 mm to 9 mm, or 6 mm to 12 mm, and a delivery diameter D1 that is smaller than the deployed diameter D2. For example, in some instances, the ratio of the delivery diameter D1 of the device 106 to the deployed diameter D2 (not shown) of the device 106 is less than about 0.3, less than about 0.29, less than about 0.28, less than about 0.27, or less than about 0.26.

[0044] As shown in FIG. 2, the removable restraint 104 includes at least two interlocking strands 108 in a warp-braided configuration. For example, the removable restraint 104 can include a first interlocking strand 108a and a second interlocking strand 108b. A portion of the first interlocking strand and / or the second interlocking strand 108a, 108b can act as a deployment portion 120 configured to release the removable restraint 104 and release the device 106 from a delivery diameter D1 to a deployment diameter D2, for example, in response to a deployment force applied to the first deployment line portion. The removable restraint 104 can also include a third interlocking strand 108c and a fourth interlocking strand 108d (e.g., as seen in FIGS. 5 and 6). The third interlocking strand and / or the fourth interlocking strand 108c, 108d can also act as a deployment portion 120, for example. It is within the scope of this disclosure to form a removable restraint that includes 2, 3, 4, 5, 6, 7, 8, 9, any even number of interlocking strands, or any odd number of interlocking strands. In one embodiment, the deployment portions 120 are joined together to form a single deployment segment 121. In some embodiments, the deployment portions 120 include the proximal ends 110 of one or more strands 108 that can be combined to define a single deployment segment 121.

[0045] In some examples, the device 106 is self-biased toward the deployed diameter and exerts a radially outward force when constrained at the delivery diameter D1. In some examples, an expansion force (e.g., a balloon) can additionally or alternatively be applied to the device 106 such that the expansion force acting on the device 106 exerts a radial force on the restraint. Also, the restraint 104 can be released prior to applying the expansion force to the device 106. When the device 106 is self-expanding, radial force generally refers to a force caused by the device 106 acting on the removable restraint 104 at any point during the deployment of the device 106.

[0046] As discussed above, the interlocking strands 108 are adapted to be detached with a deployment force applied to the deployment portion 120. A low deployment force may be preferred to allow for dismantling of the removable restraint 106 so that the device may be deployed without the need to apply large forces to the deployment portion 120 that may unintentionally displace the device 106 from the target location. In some instances, a lower profile can be achieved for a given deployment force by utilizing multiple (e.g., 2, 3, 4) knit rows with smaller strands compared to a similar deployment force (or restraining force) from a larger strand single knit row deployment. The strands can include diameters from about 0.0010 inches to about 0.0100 inches. For example, the interlocking strands 108 used to form the removable restraint 104 have a diameter of about 0.0038 inches to about 0.0054 inches. To maintain a low profile, the interlocking strands 108 can each have a diameter of less than 0.0060 inches. At an even lower profile, the interlocking strands 108 can each have a diameter of less than 0.0040 inches. Because the interlocking strands 108 are engaged as discussed herein, the profile can be minimized while maintaining sufficient restraining force (and adequate deployment force). In some instances, the ratio of this radial force of the device 106 to the deployment force applied to the deployment portion 120 is less than about 500:1. In other instances, the ratio of this radial force of the device 106 to the deployment force applied to the deployment portion 120 is less than about 475. Furthermore, the ratio of this radial force of the device 106 to the deployment force applied to the deployment portion 120 is less than about 450. Furthermore, the ratio of this radial force of the device 106 to the deployment force applied to the deployment portion 120 is less than about 425 in other instances.Further, the ratio of radial force to deployment force can be, for example, between about 10, 20, 30, 40, 50, 100, 200, 300, 400 (or any number in between) and about 500, between about 10, 20, 30, 40, 50, 100, 200, 300, 400 (or any number in between) and about 475, between about 10, 20, 30, 40, 50, 100, 200, 300, 400 (or any number in between) and about 450, or between about 10, 20, 30, 40, 50, 100, 200, 300, 400 (or any number in between) and about 425.

[0047] In some embodiments, one or more of the strands 108, including the interlocking strands 108a, 108b, 108c, 108d, may be formed from a variety of materials including, for example, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), polyester, fluoropolymers such as polyurethane, perfluoroelastomers, silicones, urethanes, aramid fibers, and combinations thereof. Other embodiments of the strands 108 may include high strength polymer fibers such as ultra high molecular weight polyethylene fibers (e.g., Spectra®, Dyneema Purity®, etc.) or aramid fibers (e.g., Technora®, etc.).

[0048] The various strands 108 may be selected to have specific properties, such as strand thickness, strand denier, strand coefficient of friction, strand material, strand treatment, strand coating, and strand stiffness. Similar to strand thickness, the use of different strand materials for the strands 108 may increase or decrease friction between the first interlocking strand and the second interlocking strand 108, helping to maintain or optimize the device 106 in the delivery configuration. Each of the various strands may be selected to include the same or different strand properties based on the application for which the removable restraint is to be used. It will be appreciated that the properties of the strands 108 may also be altered by treatment, configuration, and modification, in addition to material selection. For example, the strands may include filler or core materials and may be surface treated by etching, deposition, or corona or other plasma treatment, among other types of treatments, including coating with an appropriate coating material.

[0049] Referring to FIG. 2, which provides an exemplary embodiment of a removable restraint 104 restraining an expandable device 106, the removable restraint 104 includes knit rows 130 formed by knitting various strands 108. Any number of knit rows 130 can be implemented in association with the removable restraint. For example, the removable restraint 104 can include a first knit row 130a, a second knit row 130b, and a third knit row 130c. As seen in FIG. 2, the knit pattern is superimposed on the removable restraint 104 for reference. Each of the knit rows 130a, 130b, 130c shown in FIG. 2 acts as a release area where the removable restraint 104 is operable to release and release or deploy the expandable device 106. The knit rows 130 can be defined along at least a portion of the longitudinal length of the removable restraint 104. In some embodiments, the knit rows 130 are coextensive along the longitudinal length of the removable restraint 104. The knit rows 130 can also be circumferentially spaced from one another along the outer dimension or circumference of the removable restraint 104. The knit rows 130 can be spaced approximately equidistantly around the circumference of the removable restraint 104, or can be offset as desired.

[0050] The circumferential distance between knit rows 130 can be described in terms of an arc angle in embodiments where the removable restraint surrounds the device 106. In some embodiments, the knit rows 130 can be disposed on a first surface of the removable restraint 104 such that all knit rows 130 are disposed within about 180 degrees of the removable restraint 104. The knit rows 130 can be spaced apart from one another around the circumference of the removable restraint 104 by between about 10 degrees and about 180 degrees, between about 20 degrees and about 30 degrees, between about 30 degrees and about 45 degrees, between about 45 degrees and about 60 degrees, between about 60 degrees and about 75 degrees, between about 75 degrees and about 90 degrees, between about 90 degrees and about 105 degrees, between about 105 degrees and about 120 degrees, between about 120 degrees and about 135 degrees, between about 135 degrees and about 145 degrees, between about 145 degrees and about 160 degrees, between about 160 degrees and about 180 degrees. For example, the knit rows can be spaced about 180 degrees apart from one another, about 90 degrees apart from one another, about 60 degrees apart from one another, or any other distance as desired.

[0051] 2, according to some examples, the removable restraint 104 includes three knit rows 130a, 130b, 130c. The knit rows 130a, 130b, 130c are formed by interlocking the various strands 108a, 108b, 108c described above. It is understood that the removable restraint 104 is not limited to only three knit rows, but may be implemented with any number of knit rows, including a fourth knit, a fifth knit row, or any number of knit rows. In some embodiments, the number of knit rows corresponds to the number of strands implemented in forming the removable restraint 104.

[0052] The removable restraint 104 may include deployment portions 120 that together form a single deployment segment 121. The single deployment segment 121 is configured to deploy the device 106 by disengaging the removable restraint 104 from the device 106. This occurs by releasing the knit row 130, thereby releasing a portion of the body of the removable restraint 104. In one embodiment, the first deployment line 108a extends from and engages (e.g., forms part of) the first knit row 130a, such that the first deployment portion 120 is operable to disengage or release at least a first portion of the first knit row 130a. The single deployment segment 121 includes each portion of the strand 108 that comprises the knit row 130. Each of the knit rows 130 is operable to sequentially release when the single deployment segment 121 is engaged.

[0053] One example is shown in FIG. 3, where the removable restraint 104 has a first knit row 130a, a second knit row 130b, and a third knit row 130c. As seen in FIG. 3, the first knit row 130a and the second knit row 130b are spaced apart from one another about 90 degrees along the outer dimension of the removable restraint 104. The second knit row 130b and the third knit row 130c are also spaced apart from one another about 90 degrees along the outer dimension of the removable restraint 104. Thus, the first knit row 130a and the third knit row 130c are spaced apart from one another about 180 degrees along the outer dimension of the removable restraint 104. As shown in FIG. 3, all three of the knit rows 130 may be substantially disposed on the front surface 140 of the removable restraint 104, but no knit row is disposed on the back surface 142. The spacing of the knit rows 130 may be varied as described above.

[0054] 3, various knits may be disposed within each of the knit rows 130 along the longitudinal length of the removable restraint 104. For example, the first knit row 130a includes a first knit 132a, a second knit 132b, a third knit 132c, etc. The second knit row 130b also includes a first knit 132a, a second knit 132b, a third knit 132c, etc. The third knit row 130c also includes a first knit 133a, a second knit 133b, a third knit 133c, etc. Each of the knits 131, 132, 133 includes an interwoven portion of at least one of the strands 108.

[0055] With reference to FIG. 4, an exemplary embodiment of a knit pattern is provided. The knit pattern of FIG. 4 includes a first strand 108a, a second strand 108b, and a third strand 108c. The first strand, the second strand, and the third strand 108 include separate patterns represented by a first pattern 150, a second pattern 152, and a third pattern 154, respectively. In some embodiments, each pattern can be implemented on a knitting machine (e.g., a circular warp knitting machine, a straight bar, a flat bar, a raschel, a Milanese, a tricot, etc.). To implement a particular pattern, the knitting machine can include multiple bars. For example, the first strand 108a can correspond to a first bar 200, the second strand 108b can correspond to a second bar 202, and the third strand 108c can correspond to a third bar 204, where each bar implements one or more different patterns. In some embodiments, the different patterns can include a phase shift relative to each other.

[0056] While the removable restraint 104 is not limited to a particular manufacturing process, the following knit structures are provided in association with and implemented on a knitting machine (e.g., circular warp knitter, straight bar, flat bar, raschel, milanese, tricot). The following knit structures are four course repeats. The first bar 200 in this example includes the following repeat knit structure: 1-2 / 0-2 / 0-1 / 2-1. As the knit structure is repeated, a chain or pillar knit is formed between the first course and the last course of the knit structure. Note that since a tubular structure is being formed, knit courses 0-2, then 0-1 are such that the first strand 108a extends across 2 and 1 between 0-2 and 0-1. It is understood that two needle bars (not shown) may be implemented to form the tubular structure. The second bar 202 in this example includes the following repeat knit structure: 0-1 / 2-1 / 1-2 / 0-2. As with the first bar 200, when the four course structure is repeated, knit courses 0-2, then 0-1 are such that the second strand 108b extends between 0-2 and 0-1 across 2 and 1. In this example, the first strand 108a and the second strand 108b include similar knit structures that are out of phase with each other. The third bar 204 in this example includes a repeating knit structure of 2-0 / 1-0 / 2-0 / 1-0. The third strand 108c alternates between two positions within the knit structure. In other words, the first and second strands 108a, 108b may be described as having chain or pillar knits in a common knit row (e.g., second knit row 130b) and then alternating between two adjacent knit rows (i.e., adjacent to the common knit row) across the common knit row (e.g., first knit row and third knit row 130a, 130c across second knit row 130b). The third strand 108c alternates between two knit rows (e.g., between the first knit row and third knit row 130a, 130c, but rather than across the second knit row 130b, between each other because the knit structure is tubular).Thus, in this example, the first and second strands 108a, 108b can be considered cooperating strands when they interact with at least three of the knit rows 130, and the third strand 108c can be considered an actuating strand when it interacts with fewer than three knit rows. Note that each knit in this knit structure is an open knit. The open knit structure facilitates release of the removable restraint 104 and, therefore, deployment of the expandable device 106.

[0057] It should be noted that the embodiments disclosed above may be implemented with more than three strands, including embodiments having a number of strands that is a multiple of three (e.g., 6 strands, 9 strands, 12 strands, etc.) In those embodiments, instead of the first knit row and the third knit row 130a, 130c looping back to connect to one another, the third knit row 130c can instead extend to a fourth knit row (not shown), where the fourth knit row begins to repeat the disclosed pattern.

[0058] 5, an example is provided in which the removable restraint 104 has a first knit row 130a, a second knit row 130b, a third knit row 130c, and a fourth knit row 130d. As seen in FIG. 5, each of the knit rows 130 are equally spaced apart. Specifically, the first knit row 130a and the second knit row 130b are disposed about 90 degrees apart from each other along the outer dimension of the removable restraint 104. The second knit row 130b and the third knit row 130c are similarly spaced about 90 degrees apart from each other along the outer dimension of the removable restraint 104. Thus, the first knit row 130a and the third knit row 130c are spaced about 180 degrees apart from each other along the outer dimension of the removable restraint 104. The third knit row 103c and the fourth knit row 103d are spaced about 90 degrees apart from each other along the outer dimension of the removable restraint 104. Thus, the second knit row 130b and the fourth knit row 130d are spaced approximately 180 degrees apart from one another along the outer dimension of the removable restraint 104. As mentioned above, the spacing of the knit rows 130 can be varied such that the knit rows are not evenly spaced apart.

[0059] As seen in FIG. 5, various knits may be disposed within each of the knit rows 130 along the longitudinal length of the removable restraint 104. For example, the first knit row 130a includes a first knit 131a, a second knit 131b, a third knit 131c, etc. The second knit row 130b also includes a first knit 132a, a second knit 132b, a third knit 132c, etc. The third knit row 130c also includes a first knit 133a, a second knit 133b, a third knit 133c, etc. The fourth knit row 130d also includes a first knit 134a, a second knit 134b, a third knit 134c, etc. Each of the knits 131, 132, 133, 134 includes an interwoven portion of at least one of the strands 108.

[0060] With reference to FIG. 6, an exemplary embodiment of a knit pattern is provided. The knit pattern of FIG. 6 includes a first strand 108a, a second strand 108b, a third strand 108c, and a fourth strand 108d. In this knit pattern, the first and third strands 108, 108c have a separate knit pattern from the second and fourth strands 108b, 108d. A first knit pattern 150 is shown on a first bar 200, and a second knit pattern 152 is shown on a second bar 202. Since the first and third strands 108a, 108c include the same first pattern 200, they can be woven on the same bar at the same time. Here, the strands are laterally spaced apart from each other. The same applies to the second and fourth strands 108b, 108d. In some embodiments, each pattern can be implemented on a knitting machine (e.g., tricot, Milanese, raschel, etc.). Note that the first and second strands 108a, 108b have a similar overall pattern, but in this embodiment include a phase shift relative to each other and are therefore implemented on separate bars. The same is true for the third and fourth strands 108c, 108d in this embodiment.

[0061] While the removable restraint 104 is not limited to a particular manufacturing process, the following knit structure is provided in association with and implemented on a knitting machine. The following knit structure is a four course repeat. The first bar 200 in this example includes the following repeat knit structures: 1-2 / 3-2 / 0-1 / 2-1 and 3-0 / 1-0 / 2-3 / 0-3 for the first strand 108a and the third strand 108c, respectively. As the knit structure repeats, a chain or pillar knit is formed between the last course of the repeat pattern in the knit structure and the first course of the pattern. Note that as a tubular structure is formed, the knit can extend to form a tubular structure. This can be accomplished in some embodiments by implementing a two needle bar (not shown). The second bar 202 in this example includes the following repeating knit structures for the second strand 108b and the fourth strand 108d: 0-1 / 2-1 / 1-2 / 3-2 and 2-3 / 0-3 / 3-0 / 1-0. As can be seen, chain or pillar knits are included in both the second strand 108b and the fourth strand 108d. In this example, the first strand 108a and the second strand 108b include similar knit structures that are out of phase with each other. Because the first strand and the second strand 108a, 108b include similar knit patterns that are out of phase with each other, the first strand and the second strand 108a, 108b may be described as having chain or pillar knits in a common knit row (e.g., the second knit row 130b) and then alternating between two adjacent (i.e., adjacent to the common knit row) knit rows across the common knit row (e.g., the first knit row and the third knit row 130a, 130c across the second knit row 130b).Similarly, the third and fourth strands 108c, 108d may be described as alternating between a common knit row (e.g., the fourth knit row 130d) and then two adjacent (i.e., adjacent to the common knit row) knit rows across the common knit row (e.g., the first knit row and the third knit row 130a, 130c across the fourth knit row 130d). Thus, in this example, the first, second, third and fourth strands 108a, 108b, 108c, 108d may all be considered cooperating strands, since the strands interact with both knit rows adjacent to the knit row in which the chain or pillar knit is formed. Note that each knit in this knit structure is an open knit. The open knit construction facilitates release of the removable restraint 104 and, therefore, deployment of the expandable device 106.

[0062] 6, each of knit rows 130a, 130b, 130c, 130d includes a warp knit. Note that the removable restraint 104 includes a chain or pillar knit in two of the four knit rows (e.g., the first knit row and the third knit row 130a, 130c). Because two of the four knit rows include a chain or pillar knit, two strands that include a chain or pillar knit in the same knit row include the same pattern, only the pattern is out of phase by two courses (e.g., the first strand 108a, 108b includes a chain or pillar knit in the third knit row 103c and has the same pattern that is out of phase with each other by two courses). Note that only strands that form a chain or pillar knit in the same knit row interact with each other to form a knit in the knit row in which they form a chain or pillar knit (e.g., only the first and second strands 108a, 108b interact to form a knit in the third knit row 103c).

[0063] As mentioned above, the embodiment shown in FIG. 6 includes two strands woven on a single bar (e.g., the first and third strands 108a, 108c are woven on the first bar 200). The two strands can be implemented on one bar because they are woven using the same pattern but offset in different knit rows. The strands can be considered to be in phase with each other. Because two strands are in phase with each other and the other two strands are out of phase by two courses, a chain or pillar knit is formed in the removable restraint between every two courses (e.g., between courses II and III and between courses IV and V). This is a result of the two bars 150, 152 including a knit pattern that is out of phase by two courses. In knit rows that include a chain or pillar knit, the chain or pillar knit occurs in the knit row between every fourth course (e.g., the third knit row 103b has a chain or pillar knit between courses IV and V and between courses VIII and IX). It should also be noted that in this embodiment, each of the strands interacts with each of the remaining strands to form a knit (e.g., first strand 108a interacts with second strand 108b to form a knit, third strand 108c to form a knit, and fourth strand 108d to form a knit). As the various strands interact with each other and with the various knit rows, the restraining force of the removable restraint 104 is increased. This also reduces the occurrence of uncontrolled, spontaneous or accelerated deployment because each of the strands actuates substantially simultaneously to deploy the removable restraint 104 in a sequential pattern dictated by the knit pattern. Because each strand can include a different knit pattern or be out of phase with each other, the slack of each strand can be unequal after knits from the same course are deployed, which can also reduce the occurrence of uncontrolled, spontaneous or accelerated deployment.

[0064] The embodiments disclosed above may be implemented with more than four strands, including embodiments having a number of strands that is a multiple of two (e.g., 2 strands, 6 strands, 8 strands, 10 strands, etc.).

[0065] 2, the removable restraint 104 can include a single deployment segment 121 that includes an extension or free end of each strand that forms each knit row 130. When the single deployment segment 121 is engaged or tensioned such that the free portion of each strand 108 advances away from the removable restraint 104, the first knit (e.g., first knit 131a, 132a, 133a, 134a) of each knit row (e.g., first, second, third and fourth knit rows 130a, 130b, 130c, 130d) releases. As the single deployment segment 121 continues to be tensioned and translated away from the removable restraint 104, the second knit (e.g., 131b, 132b, 133b, 134b) of each knit row releases. This occurs until each row of knits has partially or completely released.

[0066] In some embodiments, the interwoven strands 108 are woven such that the knit rows 130 unfold substantially simultaneously to facilitate release of the knit rows. Because the strands 108 are all interwoven, if any of the knit rows advance or release at a different rate than the other knit rows, the strands forming the other knit rows may prevent proper release of the previous knit row. This occurs due to binding or restriction of the strands 108 in one knit row until the other knit row advances sufficiently to release the strands from the other knit row. Because all of the strands 108 may be interwoven, this restriction of unfolding may occur when any one of the knit rows 130 unfolds unevenly relative to one another.

[0067] For example, if a first knit 131a in a first knit row 130a is released and the first strand 108a is tensioned such that the corresponding first knit (e.g., first knit 132a in a second knit row 130b) is not released, a strand from the corresponding first knit interacting with a second knit 131b in the first knit row can impede the release of the second knit 131b. In this example, the first strand 108a can be interwoven with the remaining strands in any one knit row 130 such that the first strand 108a cannot advance further until other strands forming the other knits constraining the first strand 108a are released from the other knits by the release or release of the other knits. However, if the other knits are released, the first strand 108a can be released from the other strands at a limited location such that tension across the first strand 108a initiates deployment of the subsequent knit, which is then released. In this manner, the interweaving of the various strands 108 within each knit row 130 limits uneven deployment of the various knit rows 130.

[0068] In some embodiments, each corresponding knit in the knit row 130 must be deployed before the subsequent knit in the knit row can be sequentially deployed. Because the coordinating strands interact with at least three knit rows, the coordinating strands can provide increased stability, increased restraint, and increased resistance to accelerated deployment associated with the expandable device and deployment of the knit row 130 of the removable restraint 104. The coordinating strands can also increase the maximum restraint force of the removable restraint 104 based on the interactions described herein. In other embodiments, the strands 108 are interwoven such that a subsequent knit can be deployed when a corresponding knit in another knit row is not deployed. In yet another embodiment, the strands 108 are interwoven such that a subsequent knit in the knit row (e.g., second knit 131b) can be deployed when a corresponding knit (e.g., corresponding first knit 133a) is not deployed. However, a knit following the subsequent knit (e.g., third knit 131c) can be restrained when a corresponding knit is not deployed. The interweaving pattern of the various strands can be varied to provide different interactions between knit rows to limit release. For example, a knit row can be advanced or released 2, 3, 4, or 5 knits beyond the release of corresponding intact knits in other knit rows based on the weaving or knitting pattern. By varying how far a knit row can advance beyond other knit rows upon release, the precision of deployment can be altered when delivering and deploying the device 106.

[0069] Turning now to a discussion of methods of making and using the removable constraint, a method of deploying a device including the disclosed removable constraint is provided. As described above, the medical device can include an expandable device that can expand and contract to various diameters, including a first constrained diameter D1 and a second expanded diameter D2. The expandable device can be maintained in a constrained configuration by a removable constraint, which includes a plurality of strands interwoven to form a first release zone and a second release zone, each of which includes a knit row having a plurality of knits. In some embodiments, at least one deployment line extends from each of the release zones.

[0070] A method of deploying a medical device can include intravenously delivering the device to a treatment site. An expandable medical device is placed in a patient, where the expandable medical device is constrained by a removable restraint in a compressed configuration. The knitted array is configured to release the removable restraint from the expandable medical device via a single deployment segment. A user can hold the single deployment segment (e.g., including the free ends of the strands forming the removable restraint) away from the expandable medical device, i.e., outside of the intravenous access site. The user can then apply sufficient force to the single deployment segment to release the knitted array. Once the knitted array is released, the medical device is free from the removable restraint and can be deployed within the patient's anatomy. Thus, once the knitted array is released, the removable restraint is at least partially degraded and the expandable device can expand from a constrained diameter to a deployed diameter.

[0071] In some embodiments, the method includes applying sufficient force to the free ends of the strands simultaneously, or applying such force in relatively close temporal sequence. As discussed above, this step can be important when multiple strands are interwoven, such that the knits prevent the release or deployment of corresponding knits. When the free ends of the strands are activated, they can be translated away from the delivery site. Multiple lines can be removed via a catheter.

[0072] The present disclosure also relates to a method of manufacturing an expandable medical device. The method can include compressing an expandable member radially inward to a first compressed diameter. A plurality of strands can be interwoven to form a removable restraint. The removable restraint can be interwoven such that the strands form at least three knit rows. The method can include providing free ends of the strands such that at least a portion of each strand extends away from the removable restraint. The free ends can be operable to dismantle the removable restraint when deployed substantially simultaneously. The method can also include joining the free ends such that the free ends form a single deployed segment.

[0073] In some embodiments, the method of manufacture includes compressing the expandable member simultaneously with forming the removable restraint, such that the plurality of strands provide a compressive force on the expandable member as the strands are woven around the expandable member.

[0074] In some embodiments, the covering member can be woven over a mandrel. Once the covering member is woven, and in some embodiments partially expanded, the covering member can be removed from the mandrel and applied over the radially compressed implantable medical device.

[0075] The invention of this application has been described above both generally and with reference to specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope of the present disclosure. Therefore, the embodiments are intended to cover the modifications and variations of the present invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A knitted tubular structure comprising a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

2. 2. The knitted tubular structure of claim 1, wherein corresponding knits in each of the at least two knit rows are configured to release substantially simultaneously as the at least two knit rows release progressively along the longitudinal length of the body.

3. The knitted tubular structure of claim 1 or 2, wherein a first fiber of the plurality of fibers defines a chain knit within one of the at least two knit rows.

4. 4. The knitted tubular structure of claim 3, wherein the plurality of knits form a first knit row, a second knit row, and a third knit row, and the first fiber interacts with each of the first knit row, the second knit row, and the third knit row along a longitudinal length of the body.

5. The knitted tubular structure of claim 4 , wherein second fibers of said plurality of fibers alternate between said first knit row and said second knit row along the longitudinal length of said body.

6. 3. The knitted tubular structure of claim 1 or 2, wherein the plurality of fibers includes first fibers, second fibers, third fibers, and fourth fibers, each of the first fibers, second fibers, third fibers, and fourth fibers defining a corresponding chain knit.

7. 7. The knitted tubular structure of claim 6, wherein the at least two knit rows include a first knit row, a second knit row, a third knit row, and a fourth knit row, the first fiber and the second fiber defining corresponding chain knits in the first knit row, and the third fiber and the fourth fiber defining corresponding chain knits in the third knit row.

8. The knitted tubular structure of claim 7 , wherein the fibers interact with the second fibers in the first knit row, with the third fibers in the second knit row, and with a fourth fiber in the fourth knit row.

9. The knitted tubular structure of any preceding claim, wherein the plurality of knit rows are spaced laterally about a surface of the body.

10. The knitted tubular structure of any one of claims 1 to 9, wherein the plurality of fibers each have a diameter of less than 0.0060 inches.

11. an expandable member configured to radially expand from a first diameter to a second diameter; and a knitted tubular structure configured to radially releasably constrain the expandable member; A medical device comprising: A medical device, wherein the knitted tubular structure includes a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

12. 12. The medical device of claim 11, wherein the knitted tubular structure includes a first knit row, a second knit row, and a third knit row, the plurality of fibers of the knitted tubular structure include coordinating fibers and actuating fibers, the coordinating fibers form at least a portion of the knit in the first, second, and third knit rows, and the actuating fibers form at least a portion of the knit in only two of the first, second, and third knit rows.

13. The medical device of claim 12 , wherein the knitted tubular structure comprises at least two cooperating fibers.

14. 13. The medical device of claim 12, wherein the knitted tubular structure includes a first knit row, a second knit row, a third knit row, and a fourth knit row, and the plurality of fibers of the knitted tubular structure include coordinating fibers, the coordinating fibers forming at least a portion of a knit in at least three of the first, second, third, and fourth knit rows.

15. The medical device of claim 14 , wherein the cooperating fibers form a chain knit in at least one of the first, second, third and fourth knit rows.

16. The medical device of claim 15 , wherein the plurality of fibers comprises a plurality of cooperating fibers.

17. The medical device of any one of claims 12-16, wherein the cooperating fibers are operable to increase resistance to deployment when the knit rows are not deployed substantially simultaneously.

18. The medical device of any one of claims 12 to 17, wherein the cooperating fibers are operable to increase the maximum restraining force of the knitted tubular structure.

19. The medical device of any one of claims 11 to 18, wherein the at least two rows of knit of the knitted tubular structure are operable to release substantially simultaneously longitudinally along the body.

20. 1. A method of deploying a medical device, comprising: placing an expandable member within a patient, wherein the expandable member is constrained in a compressed configuration by a knitted tubular structure, the knitted tubular structure including a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body, the plurality of fibers including a deployment portion; maintaining a deployed portion of the plurality of fibers away from the expandable medical device; and applying a sufficient force to the deployed portion of the plurality of fibers to release at least a portion of the knit row; The method comprising:

21. radially compressing the expandable member to a compressed profile; and providing a knitted tubular structure about the expandable member to constrain the expandable member in the compressed profile; wherein the knitted tubular structure comprises a plurality of fibers forming a body having a longitudinal length, the plurality of fibers defining a plurality of knits, the plurality of knits forming at least two knit rows extending longitudinally along the body, the at least two knit rows configured to gradually release along at least a portion of the longitudinal length of the body.

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