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 deform 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. Some stents are designed to elastically recover by being manufactured at their functional diameter of a material that has elastic recovery properties, and then radially compressed to be mounted on a delivery catheter.

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. The devices may be held in this compressed state for a prolonged period of time (e.g., after manufacture and prior to use). Different mechanisms or devices may be used to hold the stent and stent-graft devices in a delivery state and be removed to allow expansion of the stent and stent-graft devices at the target location. <CIT> is directed to a procedure for inserting an implant comprising a tubular body with the aid of a flexible sleeve. The tube is implanted in a compressed state, held by a filament in a series of loops which are released after withdrawing the sleeve by pulling on the filament end situated outside the patient's body. The implanted tube is made, for example, from polyethylene terephthalate, polyester of PTFE, with a wall thickness of <NUM> and <NUM>. It can be between <NUM> and <NUM> long by <NUM> to <NUM> in diameter. <CIT> is directed to an implantation device of a duodenum stent characterized in that the device comprises a core tube which is used for bearing the duodenum stent; the wall of the core tube is provided with a first binding wire channel and a first stent binding wire window; and the first binding wire channel is internally provided with a first binding wire which is used for fixedly binding the duodenum stent. The implantation device of the duodenum stent can conveniently and reliably realize withdrawing after implantation of the duodenum stent. The main chamber of the core tube is provided with radial liquid discharging holes so that distilled water is injected through a handle liquid injection hole in retreating the implantation device and flows to a clearance between a stent sleeve and the implantation device. In injection of the distilled water, the implantation device of the duodenum stent is withdrawn and simultaneously rotated in a left-and-right direction for preventing packaging of the implantation device by the sleeve of the stent and furthermore preventing withdrawing of the implantation device from the stent sleeve.

A first aspect of the invention relates to an apparatus as defined in independent claim.

In a second aspect there is provided a delivery system according to the invention, the delivery system including an implantable medical device; and a constraining mechanism as described above.

According to preferred embodiments each of the plurality of knots are in contact with adjacent ones of the plurality of knots when the constraining mechanism is in the constrained configuration.

According to preferred embodiments, the single fiber is configured to sequentially untie the plurality of knots in response to applied tension and release the constraining mechanism to allow expansion of the implantable medical device to a deployed configuration.

According to preferred embodiments, the implantable medical device includes a stent having a plurality of apices, and the single fiber is configured to release in sequence and avoid catching on the apices during release.

According to preferred embodiments, the plurality of knots are configured to maintain position relative to the implantable medical device in the constrained configuration prior to being released in sequence.

According to preferred embodiments, the plurality of knots are configured to lessen ramping of the implantable medical device prior to being released in sequence.

According to preferred embodiments, the plurality of knots are longitudinally aligned a longitudinal axis of the constraining mechanism.

According to preferred embodiments, the plurality of knots alternate sides of a longitudinal axis of the constraining mechanism.

According to preferred embodiments, the single fiber forms multiple loops are angled relative to the longitudinal axis of the constraining mechanism.

According to preferred embodiments, the multiple loops are substantially perpendicular to a longitudinal axis of the constraining mechanism formed by the plurality of knots.

According to preferred embodiments, the multiple loops are packed at a density with each loop being in physical contact with adjacent ones of the multiple loops.

For example, the multiple loops may be packed at a density configured to substantially gaplessly cover the implantable medical device and the density is between approximately <NUM> (<NUM> inches) and <NUM> (<NUM> inches).

According to preferred embodiments, the implantable medical device comprises a drug eluting coating, and the multiple loops of the constraining mechanism are configured to lessen release of the drug eluting coating prior to the constraining mechanism releasing to allow expansion of the implantable medical device to a deployed configuration.

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 as long as they fall under the scope of the claims. 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, methods, and systems that include a constraining mechanism configured to hold, compress, or constrain an implantable medical device (e.g., a stent or stent-graft) in a delivery configuration prior to and during delivery to a target location. The constraining mechanism includes a single fiber. The single fiber, as compared to certain sheaths, sleeves or multiple fiber constraining mechanisms, may constrain an implantable medical device at a smaller profile.

The single fiber, wraps the device circumferentially with each circumferential wrap of the single fiber being secured with a loop. The loop may include a loop knitting pattern along the length of the device with a plurality of knots. In addition, the single fiber constraining mechanism may facilitate deployment of the implantable medical device by avoiding catching on the implantable medical device and avoiding undesired pre-deployment of the device as discussed in further detail below. In particular, compared multiple fiber constraining mechanisms, the single fiber constraining mechanism can lessen the opportunity for catching and pre-deployment on the device.

<FIG> is a top plan view of a catheter <NUM> with a constraining mechanism <NUM>, according to some embodiments. As shown in <FIG>, the constraining mechanism <NUM> is configured to constrain an implantable medical device <NUM> to a delivery configuration. The constraining mechanism <NUM> includes a single fiber <NUM> arranged about the implantable medical device <NUM> having a plurality of knots to maintain the constraining mechanism <NUM> in a constrained configuration. The single fiber <NUM> of the constraining mechanism <NUM>, as shown in further detail with reference to <FIG>, includes a series of knots.

The constraining mechanism <NUM> is arranged along a length of the implantable medical device <NUM>. The constraining mechanism <NUM> is also circumferentially arranged about the implantable medical device <NUM> and may substantially cover the implantable medical device <NUM> for delivery. In addition, and as shown in <FIG>, the single fiber <NUM> includes a series of knots and is also circumferentially arranged about the implantable medical device <NUM> over the length of the implantable medical device <NUM> with the single fiber <NUM> being not knotted or otherwise wrapped proximal to the implantable medical device <NUM>. The single fiber <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 implantable medical device <NUM>. The single fiber <NUM> includes a proximal end <NUM> that a user may apply tension to in order to release the constraining mechanism <NUM> and deploy the implantable medical device <NUM>.

In certain instances, the single fiber <NUM> releases similar to a rip cord such that the knots sequentially release along the length of the implantable medical device <NUM>. As is explained in greater detail below, the constraining mechanism <NUM> is formed by knitting together the single fiber <NUM> directly on the implantable medical device <NUM>. As contrasted to prior multiple fiber constraining mechanisms which are knotted together and then subsequently arranged about a constrained device, the constraining mechanism <NUM> is formed directly on the implantable medical device <NUM> according to various examples. The implantable medical device <NUM> may be a stent, stent-graft, a balloon, or a similar device.

<FIG> is an illustration of an example constraining mechanism <NUM>, according to some embodiments. The constraining mechanism <NUM> may be included a portion of a delivery system (e.g., a catheter and implantable medical device as shown in <FIG>). <FIG> shows the constraining mechanism <NUM> in a constrained configuration in which an implantable medical device (not shown) is held to a diameter less than a deployed, expanded or working diameter. The constraining mechanism <NUM> is configured to constrain an implantable medical device to a delivery configuration. In addition, the constraining mechanism <NUM> includes a single fiber <NUM> arranged having a plurality of knots <NUM> to maintain the constraining mechanism <NUM> in a constrained configuration. The plurality of knots <NUM> are configured and arranged such that at least two of the plurality of knots <NUM> are in contact in the constrained configuration as shown in <FIG>.

As highlighted in <FIG>, adjacent knots 208a-b of the plurality of knots <NUM> are in physical contact. The knots 208a-b being in contact increases the density of the constraining mechanism <NUM> as compared to prior multi-fiber constrain devices. In certain instances, each of the plurality of knots <NUM> are in contact with adjacent knots as shown in <FIG>. In addition, and in certain instances, the plurality of knots <NUM> are longitudinally aligned along longitudinal axis <NUM> of the constraining mechanism <NUM>. The alignment of the plurality of knots <NUM> can facilitate densely packing of the plurality of knots <NUM>. In certain instances, the alignment of the plurality of knots <NUM> and at least two adjacent knots 208a-b of the plurality of knots <NUM> being in physical contact relates to an amount of force applied by the constraining mechanism <NUM>. In certain instances, the fiber <NUM> may be wrapped around the implantable medical device at tension in a range between <NUM> and over <NUM>.

In addition, and as discussed in further detail with reference to <FIG>, the alignment of the plurality of knots <NUM> and at least two adjacent knots 208a-b of the plurality of knots <NUM> being in physical contact facilitates deployment of an implantable medical device by avoiding catching on the implantable medical device and avoiding undesired pre-deployment of the device as discussed in further detail below.

In certain instances, the single fiber <NUM> forms multiple loops <NUM> arranged circumferentially about the implantable medical device. In addition, and as shown in <FIG>, the multiple loops <NUM> are packed at a density such that at least two loops 210a-b of the multiple loops <NUM> are in physical contact. The loops <NUM> are unknotted portions of the single fiber <NUM> between knots of the plurality of knots <NUM>. The multiple loops <NUM> may be arranged circumferentially about an implantable medical device and in certain instances, the multiple loops <NUM> are substantially perpendicular to the longitudinal axis <NUM> of the constraining mechanism <NUM>.

As compared to prior multi-fiber constraining devices, the single fiber <NUM> is configured to prevent non-sequential tensioning and un-tensioning (e.g., releasing) that can complicate deployment. The plurality of knots <NUM> of the single fiber <NUM> forming the constraining mechanism <NUM> are an interlocking structure that unravels as a coherent interwoven rip cord by unknotting the plurality of knots <NUM> on the single fiber <NUM>. As tension is applied to the proximal end <NUM> of the single fiber <NUM>, the plurality of knots <NUM> release in sequence. This process will continue along the entire length of the device until each of the plurality of knots <NUM> disengage as one long, continuous, un-knotted single fiber <NUM>.

<FIG> is an illustration of an example constraining mechanism <NUM> and implantable medical device <NUM>, according to some embodiments. The constraining mechanism <NUM> is formed of a single fiber <NUM> that includes a plurality of knots <NUM> arranged along a longitudinal axis <NUM> of the constraining mechanism <NUM>. In addition, the single fiber <NUM> forms multiple loops <NUM> arranged perpendicular to the longitudinal axis <NUM> of the constraining mechanism. The multiple loops <NUM> are also arranged circumferentially about the implantable medical device <NUM>. The single fiber <NUM> includes a proximal end <NUM> that a user may apply tension to in order to release the constraining mechanism <NUM> and deploy the implantable medical device <NUM>.

According to the invention, at least two adjacent knots 208a-b of the plurality of knots <NUM> are in physical contact and at least two loops 210a-b of the multiple loops <NUM> are in physical contact. The single fiber <NUM> may be configured to sequentially untie the plurality of knots <NUM> in response to applied tension and release the constraining mechanism <NUM> to allow expansion of the implantable medical device <NUM> to a deployed configuration.

In <FIG>, the implantable medical device <NUM> is shown in a partially deployed configuration with the constraining mechanism <NUM> having been partially released. The implantable medical device <NUM> may be a stent that includes multiple apices <NUM> with a single apex highlighted in <FIG> for ease of illustration. As noted above, the single fiber <NUM> facilitates deployment by avoiding catching on the implantable medical device <NUM>. Releasing the plurality of knots <NUM> in sequence avoid being caught on the apices <NUM> during release. The plurality of knots <NUM> may be released along the longitudinal axis <NUM> to avoid snagging on the apices <NUM>. The single fiber <NUM> avoids shifting axially relative to the implantable medical device <NUM>. In addition, releasing the plurality of knots <NUM> in sequence maintains a consistent deployment force during deployment of the expandable medical <NUM>, which may avoid misdeployment or shifting of the constraining mechanism <NUM>.

In certain instances, the plurality of knots <NUM> are configured to maintain position relative to the implantable medical device <NUM> in the constrained configuration prior to being released in sequence. The single fiber <NUM> may be configured to lessen ramping of the implantable medical device <NUM> prior to the plurality of knots <NUM> being released in sequence. As shown in <FIG>, the expandable medical <NUM> begins to expand to a larger diameter after release of the constraining mechanism <NUM>. The expandable medical <NUM> may be have an angle <NUM> between the portions held by the constraining mechanism <NUM> and portions that have been expanded or are beginning to expand. Due to the angle <NUM> and the expandable device <NUM> expending a force to deploy to the deployed diameter, prior devices may shift due to ramping of the implantable medical device <NUM>. The axial shifting of the constraining mechanism <NUM> could result in pre-deployment or the constraint to get caught on apices of the implantable medical device <NUM>. The single fiber <NUM>, however, is able to lessen ramping of the implantable medical device <NUM> by maintaining a location of each of the plurality of knots <NUM>, relative to the implantable medical device <NUM>, as the plurality of knots <NUM> are released in sequence. The single fiber <NUM>, in this manner, lessens undesired or pre-deployment of the implantable medical device <NUM>.

The multiple loops <NUM> of the constraining mechanism <NUM> may be packed at a density such that each loop <NUM> is in physical contact with adjacent ones <NUM>0a-c of the multiple loops <NUM> as noted above. In certain instances, the multiple loops <NUM> are packed at a density configured to substantially gaplessly cover the implantable medical device <NUM>. In certain instances, the density is between approximately <NUM> (<NUM> inches) and <NUM> (<NUM> inches). Further, the implantable medical device <NUM> may include a drug eluting coating and the multiple loops <NUM> of the constraining mechanism <NUM> are configured to lessen release of the drug eluting coating prior to the constraining mechanism <NUM> releasing to allow expansion of the implantable medical device <NUM> to a deployed configuration.

<FIG> is an illustration of another example constraining mechanism <NUM> and implantable medical device <NUM>, according to some embodiments. As discussed in further detail above with reference to <FIG>, the constraining mechanism <NUM> is formed of a single fiber <NUM> that includes a plurality of knots <NUM>. In addition, the single fiber <NUM> forms multiple loops <NUM> arranged about a circumference of the constraining mechanism <NUM> between the plurality of knots <NUM>.

As shown in <FIG>, the plurality of knots <NUM> are arranged on alternating sides of a longitudinal axis <NUM> of the constraining mechanism <NUM>. In addition, the multiple loops <NUM> are also arranged circumferentially about the implantable medical device <NUM>. The single fiber <NUM> forms the multiple loops <NUM> in an angled configuration circumferentially about the implantable medical device <NUM>. The multiple loops <NUM> may be angled relative to the longitudinal axis <NUM> of the constraining mechanism <NUM>. According to the invention, at least two adjacent knots 408a-b of the plurality of knots <NUM> are in physical contact. Further, at least two loops 410a-b of the multiple loops <NUM> are in physical contact. The single fiber <NUM> may be configured to sequentially untie the plurality of knots <NUM> in response to applied tension and release the constraining mechanism <NUM> to allow expansion of the implantable medical device <NUM> to a deployed configuration.

In <FIG>, the implantable medical device <NUM> is shown in a partially deployed configuration with the constraining mechanism <NUM> being partially released. In certain instances, the plurality of knots <NUM> are configured to maintain position relative to the implantable medical device <NUM> in the constrained configuration prior to being released in sequence. As shown in <FIG>, the implantable medical device <NUM> begins to expand to a larger diameter after release of the constraining mechanism <NUM>. The implantable medical device <NUM> may be have an angle <NUM> between the portions held by the constraining mechanism <NUM> and portions that have been expanded or are beginning to expand. Due to the angle <NUM> and the expandable device <NUM> exerts a force to deploy to the deployed diameter, prior devices may shift due to ramping of the implantable medical device <NUM>. The single fiber <NUM>, however, lessens ramping of the implantable medical device <NUM> by maintaining a location of each of the plurality of knots <NUM>, relative to the implantable medical device <NUM>, as the plurality of knots <NUM> are released in sequence. The single fiber <NUM>, in this manner, lessens undesired or pre-deployment of the implantable medical device <NUM>.

The device shown in <FIG> is provided as an example of the various features of the constraining mechanism <NUM> and, although the combination of those illustrated features is clearly within the scope of invention, that example and its illustration is not meant to suggest the inventive concepts provided herein are limited from fewer features, additional features, or alternative features to one or more of those features shown in <FIG>. For example, in various embodiments, the constraining mechanism <NUM> shown in <FIG> may include the density of loops described with reference to <FIG>. It should also be understood that the reverse is true as well. One or more of the components depicted in <FIG> can be employed in addition to, or as an alternative to components depicted in <FIG>. For example, the alternating knots <NUM> of the constraining mechanism <NUM> shown in <FIG> may be employed in connection with the constraining mechanism <NUM> of <FIG>.

Claim 1:
An apparatus comprising:
a constraining mechanism (<NUM>) configured to constrain an implantable
medical device (<NUM>, <NUM>) to a delivery configuration, the constraining mechanism (<NUM>) including:
a single fiber (<NUM>) arranged about the implantable medical device (<NUM>, <NUM>) having a plurality of knots (<NUM>) configured to be released in sequence and the single fiber (<NUM>) forming multiple loops (<NUM>) arranged circumferentially about the implantable medical device (<NUM>, <NUM>) in a constrained configuration, the multiple loops (<NUM>) being packed at a density such that at least two loops (210a-b) of the multiple loops (<NUM>) are in physical contact in the constrained configuration, wherein at least two of the plurality of knots (<NUM>) are in contact in the constrained configuration, and
the single fiber (<NUM>) having a substantially unknotted structure in a non-constrained configuration.