The present disclosure relates generally to treatment of certain defects in a vasculature of a patient and more particularly, to self-expanding braided stents to a treatment site in a vasculature of a patient.
Stents are understood as tubular reinforcements that can be inserted into a blood vessel to provide an open path within the blood vessel. Stents have been widely used in intravascular angioplasty treatment of occluded cardiac arteries, wherein the stent may be inserted after an angioplasty procedure to prevent restenosis of the artery. Stents are often deployed by use of delivery devices which cause the stent to open with the objective of reinforcing the artery wall and provide a clear through-path in the artery thereby preventing restenosis.
However, the weakness and non-linear nature of the neurovasculature limits the applicability of such stents in procedures, for example, in repairing neurovascular defects. Furthermore, known delivery methods are less useful in vasoocclusive surgery, particularly when tiny vessels, such as those found in the brain, are to be treated. Accordingly, a need exists for a stent that can be used with delivery techniques in vasoocclusive treatment of neurovascular defects that provides selective reinforcement in the vicinity of the neurovascular defect. A need also exist for a stent that reduces trauma or risk of rupture to the blood vessel. It is with respect to these and other considerations that the various embodiments described below are presented.
In some aspects, the present disclosure relates to a braided stent system for delivery into a blood vessel is disclosed. They system may include a stent body having a lumen formed by a plurality of braided members with interstices formed therebetween. An expansion ring may be mechanically connected to the lumen of the stent body and be operable to maintain the expansion ring in an opened state by having its frame impart an outwardly expanding radial force to the stent body. The frame may include plurality of legs joined at a first intersection and a claw portion mechanically connected to one or more of the interstices of the stent body. The claw portion may mechanically connect the expansion ring to one or more of the interstices by extending away from the first intersection through a plurality of the interstices and terminating at a locking mechanism opposite the first intersection.
In certain embodiments, the claw portion may include at least two aligned elongate members that extend between the first intersection and the locking mechanism to form a void therebetween. One or a plurality of the interstices may pass through the void as the claw portion mechanically connects the expansion ring to the stent body. The plurality of legs of the frame may also be bowed and/or oriented in a non-linear configuration causing the frame to be resistant to compression so that the braided stent system is self-expanding. The legs may be rotatable, pivotable, and/or twistable a predetermined amount about the first intersection.
In other embodiments, a braided stent system is disclosed having a stent body having a lumen formed by a plurality of braided members with interstices formed therebetween and a first expansion ring connected to the lumen of the stent body. The first expansion ring may include a frame defined by a plurality of interconnected support assemblies that are selectively positioned to impart an outwardly expanding radial force to the stent body, each support assembly can include a plurality of legs joined at a first intersection and connected to one of the other interconnected support assemblies at a second intersection opposite the first intersection. Each support assembly can also include a claw portion mechanically connected to one or more of the interstices of the stent body.
The plurality of legs of the frame may be bowed and/or oriented in a non-linear configuration causing the frame to be resistant to compression so that the braided stent system is self-expanding. The legs may be rotatable, pivotable, and/or twistable a predetermined amount about the first intersection.
The claw portion may also mechanically connect the expansion ring to inner and outer portions of the lumen by extending away from the first intersection, being interlaced through at least two of the interstices, and being terminated at a locking mechanism opposite the intersections. The locking mechanism may include a T-shaped end or outwardly extending hooked members operable to fixedly connect to the interstices of the stent body. The solution is not so limited, however, and at least one of the claw portions may include a plurality of aligned elongate members that extend between respective first intersections and locking mechanisms to form a void through which the plurality of interstices can pass.
In an example embodiment, one or a plurality of braided pairs of the braided members can pass through the void. The locking mechanism may also fixedly connect the expansion ring to the stent body by joining ends of the aligned elongate members opposite the first intersection through welding, soldering, crimping, or an adhesive bond. The solution is not so limiting, however, and the locking mechanism may fixedly connect the expansion ring to the stent body by joining ends of the aligned elongate members opposite the first intersection through a fastener such as a metallic band and/or ring. Additionally, at least one of the first and/or second intersections can form a V-shape, a U-shape, or an elliptical curve.
In another example embodiment, the stent body can include a proximal end, a distal end, and a central portion disposed therebetween. The first expansion ring can be disposed on or adjacent the distal or proximal ends of the stent body with the second intersections of the interconnected support assemblies being joined at or adjacent the respective distal or proximal ends. One or more additional expansion rings can also be connected to the lumen along or in connection with the central portion of the stent body and/or the opposing, distal or proximal end of the stent body.
A method of deploying a braided stent body into a vessel is also disclosed, the method comprising the following steps: assembling a plurality of expansion rings to a lumen of the braided stent body, the lumen of the braided stent body being formed by a plurality of braided members with interstices formed therebetween; selectively positioning each expansion ring with the braided stent body; each expansion ring imparting an outwardly expanding radial force thereby maintaining the lumen of the braided stent body in an opened position, each expansion ring comprising: a frame defined by a plurality of interconnected support assemblies comprising a plurality of legs joined at a first intersection and connected to one of the other interconnected support assemblies at a second intersection opposite the first intersection, the legs being twistable about the first and second intersections; and a claw portion disposed opposite the first and second intersections; mechanically connecting the claw portion of each ring to an inner portion of the stent body by interlacing a first elongate member extended between the respective claw portion and the respective first intersection of the expansion ring with one or more of the interstices and terminated at a locking mechanism opposite the intersections; and translating the braided members in the vessel independently from each expansion ring.
Since at least one of the claw portions can include a second alignment member substantially aligned with the first elongate member and extended between respective first intersections and locking mechanisms, the method can also include forming a void between the first and second elongate members and respective first intersections and locking mechanisms; and passing one or a plurality of braided pairs of the braided members through the void. The method may also include fixedly connecting the expansion ring to the stent body by joining ends of the first and second elongate members opposite the first intersection through welding, soldering, crimping, an adhesive bond, and/or a fastener.
Other aspects and features of the present disclosure will become apparent to those of ordinary skill in the art, upon reviewing the following detailed description in conjunction with the accompanying figures.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.
Although example embodiments of the disclosed technology are explained in detail herein, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the disclosed technology be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways.
It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. By “comprising” or “containing” or “including” it is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named.
In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the disclosed technology. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified.
As discussed herein, vasculature of a “subject” or “patient” may be vasculature of a human or any animal. It should be appreciated that an animal may be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal may be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject may be any applicable human patient, for example.
Braided stents may be formed from a plurality of elongate members (e.g. metal wires, polymeric fibers, or strands of material) and these members can be very useful in treatment of neurovascular defects. However, when such braided members are intended to be self-expanding in a lumen of a stent body, known manners of activation of the initially expanding end struggle to adequately, reliably, and fully open so that the initially expanding end can be used as an anchor point. Moreover, braided stents have been known to exhibit high internal friction that resists the inherent radial expansion force of the self-expanding braided stent when being deployed to an opened state. More specifically, the relatively high internal friction can render it difficult to open the initially expanding end of the stent which results in deficiencies in anchoring and deployment. This is particularly true for braided stents delivered to the desired vessel location through use of a delivery sheath, microcatheter, or the like, since in a closed state (e.g. compressed or crimped) the stent body typically exhibits friction between the braided members and the delivery sheath or microcatheter.
In practice, braided stents can be delivered to a particular vessel by advancing a blunt surface against a proximal end of the braided stent causing the braided stent to axially compress and expand radially. This expansion within the delivery sheath or microcatheter can result in an increased normal force being applied to the inner surface of the delivery sheath, microcatheter, or the like thereby also increasing friction caused by the braided stent.
Known solutions to these issues have depended on factors such as material, size, cell design, internal friction, and extra manipulation by the end-user to reliably, quickly and adequately open the braided stents. In turn, success of the braided stent relied heavily on end-user accuracy in delivery which unnecessarily increases risk of injury to the patient.
Moreover, such braided, self-expanding stents can be difficult to recapture after being delivered and/or deployed. It is to be understood that a “self-expanding” stent is a stent wherein the particular stent fully deploys upon emerging through a delivery device such as a sheath, microcatheter, or the like. In this respect, when a self-expanding stent body emerges, unrestrained outside of the respective delivery device, the self-expanding braided stent should expand and be deployed in the vasculature. However, due to the referenced radial forces and friction, stent deployment and recapture following deployment is difficult.
The herein disclosed expansion ring 1 resolves these and other issues by providing a secure, mechanical attachment between ring 1 and the corresponding, braided stent body 12 that increases an outwardly extending radial expansion force of an initial proximal deployment end 6 of body 12, an opposing distal end 8 of body 12, and/or a central portion defined between each end 6 and 8. Instead, ring 1 includes one or a plurality of interconnected support assemblies 10 that collectively cause the ring to fully anchor itself with the lumen 20 of body 12 by mechanically securing a claw 17 of each assembly 10 to be interlaced with the braided, elongate members 22 of body 12. As a result, the total internal friction of body 12 is reduced and members 22 can move body 12 independent from ring 1 as discussed more particularly below. Assembling one or more multiple rings 1 with body 12 results in relatively easy delivery without the need for accurate positioning of ring 1 with body 12. In turn, deployment of the body 12 within the vasculature is more reliable with reduced risk of injury for the end-user.
In the following description, references are made to the accompanying drawings that form a part hereof and that show, by way of illustration, specific embodiments or examples. In referring to the drawings, like numerals represent like elements throughout the several figures. Turning to
As can be seen, body 12 of
Turning to
By adding claw 17 to the end of a crown of each assembly 10, each ring 1 is allowed to interlace with body 12 without a permanent or rigid attachment to body 12 such as welding, soldering or a chemical adhesive. Once the claw 17 is effectively interlaced and connected with the body 12 and the desired location, braided members 22 can also move independently from ring 1 which removes the adverse impact that a permanent or rigid attachment previously had on body 12 to fully expand when assembled with an expansion ring.
Intersection 31 may also include a rotatable and/or twistable coupling so that each assembly 10 of ring 1 is capable of flexing a predetermined amount when body 12 and ring 1 is in use. One or more elongate members 18 may extend from intersection 31 and terminate at a locking mechanism 40 opposite intersection 31 and legs 28 and 30. In the embodiment of
In order to mechanically attach to body 12, each claw 17 may have respective members passed through and/or interlaced with interstices 24 and members 22 and then joined at mechanism 40. In this regard, one or more multiple braided pairs 26 of members 22 may be arranged in or in connection with void 5 so that claw 17 may be mechanically attached to inner and outer portions of lumen 20. Mechanism 40 of
Turning to
Turning to
Each assembly 10 and its constituent features may be formed of a superelastic material, such as a nickel-titanium alloy or Nitinol, or may be formed of a non-superelastic material, such as spring steel or MP35N, an alloy of 35% nickel, 35% cobalt, 20% chromium, and 10% molybdenum, by weight. Legs 28 and 30 of each assembly 10 may also be formed from a shape memory material having a shape memory position in the opened state.
Turning to
Turning to
Alternative claw designs are also contemplated for use with assemblies 10 of ring 1. For example, in
Turning to
The specific configurations, choice of materials and the size and shape of various elements can be varied according to particular design specifications or constraints requiring a system or method constructed according to the principles of the disclosed technology. Such changes are intended to be embraced within the scope of the disclosed technology. The presently disclosed embodiments, therefore, are considered in all respects to be illustrative and not restrictive. It will therefore be apparent from the foregoing that while particular forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.
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