Patent Description:
Stents and stent-grafts may be utilized to radially support a variety of tubular passages in the body, including arteries, veins, airways, gastrointestinal tracts, and biliary tracts. The preferred method of placing these devices has been to use specialized delivery systems to precisely place and deploy a device at the site to be treated. These delivery systems allow the practitioner to minimize the trauma and technical difficulties associated with device placements. Attributes of delivery systems include: low profile; ability to pass through introducer sheaths; ability to negotiate tortuous vasculature smoothly and atraumatically; protection of constrained devices; and ability to accurately position and deploy the device.

Stents or stent-grafts may be deployed and plastically deformed by using an inflatable balloon (e.g., balloon expandable stents) or to self-expand and elastically recover (e.g., self-expandable stents) from a collapsed or constrained delivery diameter to an expanded and deployed diameter.

These stent and stent-graft devices may be held, compressed, or constrained in the delivery configuration prior to and during delivery to a target location.

<CIT> describes a thin tubular multiple filament (film or fiber) structure that can hold high internal pressures. When desired, an extension of the filaments can be pulled in any direction to unfurl the structure. This device is useful for self expanding stent or stent graft delivery systems, balloon dilatation catheters, removable guide wire lumens for catheters, drug infusion or suction catheters, guide wire bundling casings, removable filters, removable wire insulation, removable packaging and other applications.

The invention relates to a delivery system as described according to the appended claims.

As the terms are used herein with respect to ranges of measurements "about" and "approximately" may be used, interchangeably, to refer to a measurement that includes the stated measurement and that also includes any measurements that are reasonably close to the stated measurement, but that may differ by a reasonably small amount such as will be understood, and readily ascertained, by individuals having ordinary skill in the relevant arts to be attributable to measurement error, differences in measurement and/or manufacturing equipment calibration, human error in reading and/or setting measurements, adjustments made to optimize performance and/or structural parameters in view of differences in measurements associated with other components, particular implementation scenarios, imprecise adjustment and/or manipulation of objects by a person or machine, and/or the like.

While multiple examples are 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 are to be regarded as illustrative in nature rather than restrictive in nature.

Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and apparatus configured to perform the intended functions. It should also be noted that the accompanying drawing figures referred to herein are not necessarily drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting.

Various aspects of the present disclosure are directed toward apparatuses, systems, and methods that include forming or manufacturing a constraining mechanism. The constraining mechanisms are configured to hold, compress, or constrain an implantable medical device (e.g., a stent, stent-graft, balloon, or other expandable medical device) in a delivery configuration prior to and during delivery to a target location. In certain instances, the constraining mechanism includes one or more fibers.

The constraining mechanisms, in accordance with the various aspects of the present disclosure, may be formed or manufactured directly on the implantable medical device. The fiber or fibers are knit, sewn, or interlocked to form the constraining mechanisms. Thus, the fiber or fibers are knit, sewn, or interlocked together about or around the implantable medical device. As noted above, the implantable medical devices are reduced, collapsed, or constrained to a reduced (delivery) diameter by the constraining mechanism for delivery into a target location into a patient where it is deployed or expanded to a deployed diameter (larger than the reduced diameter).

<FIG> is a top plan view of a delivery system <NUM> including a catheter <NUM> with a removable constraint <NUM>, according to some embodiments. As shown in <FIG>, the removable constraint <NUM> is configured to constrain an implantable medical device <NUM> to a delivery configuration. The removable constraint102 may include one or more fibers <NUM> arranged about the device <NUM> to maintain the removable constraint <NUM> in a constrained configuration.

The removable constraint <NUM> is arranged along a length of the device <NUM>. The removable constraint <NUM> is also circumferentially arranged about the device <NUM> and may substantially cover the device <NUM> for delivery. The one or more fibers <NUM> may be arranged within a lumen (not shown) of the catheter <NUM> and extend toward a proximal end of the catheter <NUM> that is arranged external to a patient during delivery of the device <NUM>. The one or more fibers <NUM> include a proximal end <NUM> that a user may apply tension to in order to release the removable constraint <NUM> and deploy the device <NUM>.

In certain instances, the one or more fibers <NUM> release similar to a rip cord such that interlocking portions (e.g., overlapping fibers or knots) sequentially release along the length of the device <NUM>. As is explained in greater detail below, the removable constraint <NUM> is formed by interlocking together the one or more fibers <NUM> directly on the device <NUM>. The device <NUM> may be a stent, stent-graft, a balloon, or a similar device.

<FIG> is a side view of the device <NUM> including the removable constraint <NUM>, in accordance with an embodiment. As shown, the device <NUM> includes a delivery diameter D1 and a deployed diameter D2 (not shown) that is larger than the delivery diameter D1. The removable constraint <NUM> is arranged about the device <NUM> at the delivery diameter D1. As shown, the removable constraint <NUM> includes at least two interlocking strands in the form of a warp knit. For example, the removable constraint <NUM> may include a first interlocking strand <NUM> and a second interlocking strand <NUM>. The first and/or the second interlocking strand(s) <NUM>, <NUM> may operate, for example, as a deployment line <NUM> configured to release the removable constraint <NUM> and release the device <NUM> from the delivery diameter D1 to the deployed diameter D2 in response to a knit force applied to the deployment line <NUM>.

The device <NUM> may have a desired deployed diameter D2 from about <NUM>-<NUM>, or <NUM>-<NUM>, or <NUM>-<NUM>, for example, and a delivery diameter D1 that is less than the deployed diameter D2. For example, in some instances, a ratio of the delivery diameter D1 of the device <NUM> to the deployed diameter D2 (not shown) of the device <NUM> is less than about <NUM>, less than about <NUM>, less than about <NUM>, less than about <NUM>, or less than about <NUM>.

In some instances, the first interlocking strand <NUM> has at least one strand property that is different than the second interlocking strand <NUM>, which may affect the amount of knit force required to release the removable constraint <NUM>. Examples of differing strand properties can include strand thickness, strand denier, strand coefficient of friction, strand material, and/or strand stiffness.

The first interlocking strand <NUM>, for example, may have a first diameter or thickness and the second interlocking strand <NUM> may have a second diameter or thickness that is greater than the first diameter. In various examples, use of a larger diameter or thickness for the second interlocking strand <NUM> helps increase friction between the first and second interlocking strands <NUM>, <NUM>, in turn helping maintain the device <NUM> in the delivery configuration. In some instances where the differing strand property is strand diameter or thickness, the first and second interlocking strands <NUM>, <NUM> may have a cross-sectional diameter or thickness that varies by about <NUM> (<NUM> inches). In other examples, the cross sectional diameter may vary by about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or any number therebetween. In addition, the difference in diameter between the first and second interlocking strands <NUM>, <NUM> may be between about <NUM> (<NUM> inches) and about <NUM> (<NUM> inches). For reference, the term "diameter" is not meant to require a circular cross-section, and is instead to be understood broadly to reference a maximum transverse cross-sectional dimension of a strand or effective diameter.

For reference, the term "diameter" is not meant to require a circular cross-section, and is instead to be understood broadly to reference a maximum transverse cross-sectional dimension of a strand.

In various examples, the first interlocking strand <NUM> may include a first material while the second interlocking strand <NUM> may include a second material that is different than the first material (e.g., either as an alternative to differing diameters between strands or as an additional feature). The first interlocking strand <NUM> may include a material having a different (e.g., higher or lower) tensile strength as compared to a tensile strength of a material of the second interlocking strand <NUM> in certain instances. Additionally or alternatively, the first interlocking strand <NUM> may include a material having a different (e.g., higher or lower) surface roughness as compared to a surface roughness of a material of the second interlocking strand <NUM>. Further, the first interlocking strand <NUM> may include a material having a different (e.g., higher or lower) tackiness or adherence to other materials as compared to a tackiness or adherence of a material of the second interlocking strand <NUM>. In various examples, the first and second strands <NUM>, <NUM> exhibit different coefficients of static and/or kinetic friction, with the second strand <NUM> exhibiting a relatively higher coefficient of static and/or kinetic friction than the first strand <NUM>, for example. From the foregoing, it should be appreciated that the strands <NUM>, <NUM> may include multiple different properties. For example, the first interlocking strand <NUM> may have a different (e.g., higher or lower) tensile strength and a different (e.g., higher or lower) surface roughness as compared to the second interlocking strand <NUM>.

Potential materials for strands <NUM>, <NUM> discussed herein include, for example, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), polyester, polyurethane, fluoropolymers, such as perfluoroelastomers and the like, polytetrafluoroethylene, silicones, urethanes, ultra-high molecular weight polyethylene, aramid fibers, and combinations thereof. Other embodiments for strands <NUM>, <NUM> can 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.). Generally, any of the foregoing properties may be assessed using ASTM or other recognized measurement techniques and standards, as would be appreciated by a person of ordinary skill in the field.

In certain instances, the first and second interlocking strands <NUM>, <NUM> may include the same material but may differ in other aspects. For example, one of the strands may include fillers or core materials, may be surface treated by etching, vapor deposition, or coronal or other plasma treatment, among other treatment types, including being coated with suitable coating materials. Similar to the differing diameter, use of differing strand materials for the strands <NUM>, <NUM> may increase friction between the first and second interlocking strands <NUM>, <NUM> to help maintain the device <NUM> in the delivery configuration.

The device <NUM> has a radial force at the delivery diameter D1. The radial force generally refers to the force caused by the device <NUM> acting on the removable constraint <NUM> at any point during deployment of the device <NUM>. As discussed above, the interlocking strands <NUM>, <NUM> are adapted to be removed with a deployment force applied to the deployment line <NUM>. In some instances, the ratio of this radial force of the device <NUM> to the knit force applied to the deployment line <NUM> is less than about <NUM>. In other instances, the ratio of this radial force of the device <NUM> to the knit force applied to the deployment line <NUM> is less than about <NUM>. In addition, the ratio of this radial force of the device <NUM> to the knit force applied to the deployment line <NUM> may be less than about <NUM>. In addition, the ratio of this radial force of the device <NUM> to the knit force applied to the deployment line <NUM> is less than about <NUM> in other instances. Further, the ratio of the radial force to the knit force may be between about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (or any number in between) and about <NUM>, between about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (or any number in between) and about <NUM>, between about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (or any number in between) and about <NUM>, or between about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (or any number in between) and about <NUM>, for example.

<FIG> is a schematic view of interlocking strands of the removable constraint <NUM> (<FIG>), in accordance with an embodiment. The interlocking strands (e.g., the first and second interlocking strands <NUM>, <NUM>, as shown) are generally interwoven with one another to form at least one knot row <NUM>. As shown, the knot row <NUM> is formed of interlocking loops formed from the first and second interlocking strands <NUM>, <NUM>. For example, first interlocking loops <NUM> are formed by the first interlocking strand <NUM> and are interwoven with second interlocking loops <NUM> formed by the second interlocking strand <NUM>. This interlocking, looped configuration allows for release of the removable constraint <NUM> (<FIG>) by applying the deployment force (releases knit force) to the deployment line <NUM>.

In general, the knot row <NUM> can be positioned at any location about the circumference of the removable constraint <NUM>. In certain instances, the interlocking strands may form more than one knot row. <FIG> is an end view of the removable constraint <NUM> showing example knot rows <NUM>, in accordance with an embodiment. As shown, the first and second interlocking strands <NUM>, <NUM> may form a first knot row <NUM> and a second knot row <NUM> positioned at different locations about the circumference of the removable constraint <NUM>. For example, the knot rows can be spaced approximately <NUM> degrees apart from one another, approximately <NUM> degrees apart from one another, approximately <NUM> degrees apart from one another, or any other distance as desired.

<FIG> is an end view of the removable constraint <NUM> showing example knot rows <NUM>, in accordance with an embodiment. As shown, in some instances, the removable constraint <NUM> may include more than two interlocking strands. For example, the removable constraint <NUM> may include a first interlocking strand <NUM>, a second interlocking strand <NUM>, a third interlocking strand <NUM>, and a fourth interlocking strand <NUM>, for example. In these instances, the removable constraint <NUM> can also include a first knot row <NUM>, a second knot row <NUM>, a third knot row <NUM>, and a fourth knot row <NUM> corresponding with the first through fourth interlocking strands <NUM>-<NUM>, respectively. Applying a force to one of the first through fourth interlocking strands <NUM>-<NUM> may initiate unravel of the corresponding knot row, thus allowing for selective deployment of various portions of the removable constraint <NUM>.

In some instances, at least one of the interlocking strands may have a different strand property than the remaining interlocking strands. For example, the first, second, and third strands <NUM>, <NUM>, <NUM> may have the same strand property, while the fourth strand <NUM> has a different strand property. In other examples, two of the interlocking strands may have one strand property while the remaining strands have a second strand property that is different from the first strand property, and so on. In some examples, each of the interlocking strands may have a different strand property to facilitate selective deployment of various portions of the removable constraint <NUM> as desired. In certain instances, one of the interlocking strands <NUM>, <NUM>, <NUM>, <NUM> has a different property than an adjacent one of the interlocking strands <NUM>, <NUM>, <NUM>, <NUM>.

As discussed above, the knot rows can be positioned at any location about the circumference of the removable constraint <NUM>. Though shown in <FIG> as spaced approximately <NUM> degrees apart from one another, the knot rows can be spaced any amount as desired. For example, the knot rows can be spaced <NUM> degrees apart from one another, <NUM> degrees apart from one another, or less as desired to achieve the desired deployment length ratio.

In some instances, having interlocking strands with differing properties can lessen ramping of the device <NUM> prior to being released. For example, the interlocking strands may lessen ramping (deployment angle) of the device <NUM> prior to the knots of the knot row <NUM> being released in sequence. Ramping of the device <NUM> may lead to advanced or pre-deployment of the device <NUM> prior to an intended deployment.

<FIG> are images of a delivery system in a delivery configuration and a semi-deployed configuration, respectively, in accordance with an embodiment. As shown in <FIG>, the removable constraint <NUM> is attached to the device <NUM> at its delivery diameter D1. During deployment, a knit force is applied to the deployment line <NUM> to release the removable constraint <NUM> by unraveling the knot row <NUM>, as shown in FIG. The device <NUM> is released to the deployed diameter D2 as the removable constraint <NUM> is released.

The interlocking strands <NUM>, <NUM> with differing properties can lessen ramping of the device <NUM> prior to being released. For example, the interlocking strands <NUM>, <NUM> may lessen ramping (or deployment angle) of the device <NUM> prior to the knots of the knot row <NUM> being released in sequence. The device <NUM> begins to expand to a larger diameter after release of the constraining mechanism <NUM>. The device <NUM> may be have an angle A between the portions held by the constraining mechanism <NUM> and portions that have been expanded or are beginning to expand. Due to the angle A and the device <NUM> expending a force to deploy to the deployed diameter D2, prior constrains may shift due to ramping or expansion of a portion of the device <NUM>. The differing strand properties, however, can lessen ramping of the device <NUM> by maintaining a location of each of the knots, relative to the device <NUM>, as the knots are released in sequence, lessening undesired deployment (e.g., accelerated deployment or pre-deployment) of the device <NUM> as described in detail above.

Claim 1:
A delivery system (<NUM>) comprising:
an implantable medical device (<NUM>); and
a removable constraint (<NUM>) arranged about and configured to releasably constrain the implantable medical device (<NUM>), the removable constraint (<NUM>) including at least two interlocking strands including a first interlocking strand (<NUM>) having a different strand property than a second interlocking strand (<NUM>), wherein the first interlocking strand (<NUM>) comprises a deployment line (<NUM>) configured to release the removeable constraint (<NUM>) in response to a force applied to the deployment line (<NUM>), characterized in that the different strand property comprises strand thickness.