Patent Application
20200046527
The present disclosure relates generally to the field of intravascular devices. More particularly, it concerns a self-expanding woven stent, and the methods of making the same, and the apparatus and methods for delivery of the same into a living creature.
Stents are necessary for both the arterial system and the venous system and are utilized in a wide variety of applications. In general, a stent may generally be characterized as being a balloon-expendable stent or a self-expanding stent, depending upon how deployment is affected. Self-expanding stents and balloon-expanding stents differ in many respects and have very different mechanical and dynamic properties. Various technical papers have discussed these differences in detail, and are generally known to those of skill in the art.
Balloon expanding stents are manufactured in the crimped state and are expanded to the vessel's diameter by inflating a balloon, thus plastically deforming the stent. In contrast, self-expanding stents are manufactured at the vessel diameter (or slightly above) and are crimped and constrained to the smaller diameter until the intended delivery site is reached, where the constraint is removed and the stent deployed. Accordingly, balloon expanding stents resist the balloon expansion process, whereas self-expanding stents assist vessel expansion. In other words, while self-expanding stents typically become part of the anatomy and act in harmony with native vessels, balloon-expanding stents change the geometry and properties of the anatomy. From the applicant's perspective, self-expanding stents assist, while balloon-expanding stents dictate.
While balloon-expandable stents generally reach their maximum diameter at the time of deployment (depending on the pressure of inflation), self-expanding stents typically continue to expand post deployment, reaching their maximum diameter several days to weeks later post deployment. With balloon-expandable stents, the vessel should be overdilated (e.g., +10-20%) to overcome the artery's “elastic recoil” (e.g., the tendency for the artery after dilation to return back to its original diameter). The overdilation is necessary to achieve a good apposition of the balloon-expandable stent. Without subsequent balloon dilatation, a balloon-expanding stent may become smaller in diameter over time (chronic recoil). Furthermore, the lesion should be pre-dilated before placement of the balloon-expanding stent because these stents inherently lack any expansile force. In addition, the placement of these stents frequently requires post-placement dilation to achieve optimal apposition of the stent to the vessel wall. Sometimes all of these steps (e.g., pre, during, and post deployment) consist of multiple balloon inflations. These multiple overdilations of the vessel is evidently much more injurious than the damage a self-expanding stent can cause during placement. A properly over-sized self-expanding stent, however, continues to apply a force acting to expand the vessel. Further, a self-expanding stent typically undergoes a negative chronic recoil (that is, a luminal gain), which means that a self-expanding stent continues to open over time, often remodeling the vessel profile. In general, self-expanding stents generally reside near and scaffold the outside of the vessel wall, while balloon-expanding stents remain near the lumen. The negative recoil of self-expanding stents may become an important advantage over drug eluting balloon expanding stents, in which the lumen may actually increase shortly after the deployment by inhibiting the neointima formation (new inner layer of the vessel), but this cell inhibition may result in a patchy covering layer over the stent leaving the balloon-expanding stent exposed to the flow of blood and resulting in in-stent restenosis in the long run.
Radial strength describes the external pressure that a stent is able to withstand without incurring clinically significant damage to the vessel lumen. Balloon-expanding stents can collapse if a critical external pressure is exceeded, potentially having serious clinical implications (stent crush resulting in obstruction of the lumen). On the other hand, self-expanding stents generally have no strength limitation and elastically recover even after complete flattening or radial crushing. Thus, self-expanding stents are ideally suited to superficial locations, such as the carotid and femoral arteries.
Stiffness is defined as how much the diameter of a stent is reduced by the application of external pressure. Axial stiffness is directly reflected in bending compliance. A balloon-expanding stent is typically stiffer than a self-expanding stent of identical design because of the lower elastic modulus of nitinol. Self-expanding stents are much more compliant than balloon-expanding stents of identical design, which is applicable for both delivery and deployment. Self-expanding stents typically adapt their shape to that of the vessel rather than force the vessel to the shape of the stent. Forcing a vessel into an unnatural shape, even if straight and aesthetically pleasing, can lead to high contact forces at the ends of the stent. Flexible links that are plastically deformed during bending accumulate damage and can fracture quickly as a result of fatigue.
Acute recoil refers to the reduction in diameter immediately observed upon deflation of a balloon. A balloon-expanding stent recoils after balloon deflation, whereas self-expanding stents assist balloon inflation (if needed post deployment) and thus there is no recoil of a self-expanding stent. As applied to a vessel, however, both devices generally recoil due to the spring back forces of the vessel and constrictive forces of a significant stenosis.
The delivery profile of a balloon-expanding stent is typically dictated by the profile of the balloon upon which it is mounted. In contrast, self-expanding stent profiles are typically dictated by the strut dimensions (e.g., the width) required to achieve the desired mechanical performance. Current minimum profiles of the two types are very similar, but self-expanding stents have the greater potential to reduce in size. This is expected to play an important role in neurovascular stenting, where both delivery profile and flexibility are essential.
While bending, crushing, and stretching fatigue considerations is often ignored for stents, these factors can be very important in certain indications. One extreme case is the femoral-popliteal artery, but such issues can also be important in coronary vessels because of the systolic expansion of the heart (thereby stretching the stent). For example, older generations of coronary stents were very rigid in the axial direction and not subject to axial fatigue; newer more flexible generations, however, can experience axial deformations and may be prone to fatigue damage. Nitinol performs far better than any other known metal in displacement-controlled environments such as these, which ultimately may mean that this more fatigue-resistant metal offers further advantages under various circumstances.
Newer stent platforms (both balloon and self-expanding) have been designed to increase flexibility, radial strength, torsion, and lengthening or shortening of the vessel, with decreased rates of stent fracture and restenosis. For example, newer-generation self-expanding nitinol stents have a superelastic metallic alloy of nickel and titanium and thinner struts, thereby resulting in better deliverability and less in-stent restenosis.
Percutaneous transluminal coronary angioplasty with stenting has now become one of the cornerstones of treatment for coronary artery disease (CAD). Self-expanding stents and balloon-expandable stents are routinely used in peripheral arterial disease, although balloon-expandable stents have become the stent of choice for coronary arteries. The use of third-generation drug-eluting stents (DES) is currently the preferred method of treatment for all patients with coronary artery disease.
In general, most conventional techniques for treating bifurcation lesions use a balloon expandable stent. This is no surprise, as there is an existing bias in the coronary stent market that favors third generation DES balloon expanding stents over currently available self-expanding versions. For example, one reason that self-expanding stents are not favored is that the majority of these self-expanding stents are nitinol slotted tube designs that are plagued by undesirable features such as having a weak expansile force, are crash-prone, easily break, and are not flexible enough, etc. As another example, balloon-expanding stents have traditionally provided more optimal placement within the vessel, and traditional balloon-expanding stents have provided less recoil than self-expanding stents when placed in particular locations.
However, the deployment of the balloon expanding stents are overly injurious and requires a series of overdilation of the vessel. Further, while the DES coating used with these balloon expanding systems aims to control the reactive abundant neointima formation by inhibiting the growth of the endothelial cells (which works for a short time), the patchy and partial endothelization may result in frequent in-stent stenosis and thrombosis in the long run. For example, the stent wires may not be completely covered, and the bare wires may be a source of thrombus formation (e.g., in-stent restenosis). Another negative aspect of using DES is that while the Everolimus drug inhibits growth factor-stimulated cell proliferation leading to inhibition of cell metabolism, growth, and proliferation by arresting the cell cycle at the late G1 stage, it can sensitize patients and also the use of such drug-treated stent is contraindicated in patients with any immune compromise. The amount of drug, which is released from the stent's polymer coating is said to has clinically insignificant systemic dose but still it has some potential to cause some deleterious effect in some individuals. Further, while the balloon expandable stents in general have greater outward forces after placement than a typical self-expanding stent, their ability to withstand external forces are very limited and they suffer with crush-prone designs. For example, the slotted tube nitinol balloon expanding stents are inherently brittle and breakable and are not resistant to fatigue. Further, how these balloon expandable stents are designed (such as to be flexible) further increase the possibility of fatigue (by thin connecting struts as bridges).
Stents are necessary for both the arterial system and the venous system. Relative to the arterial system, the venous system is characterized by low pressure, low velocity, large volume, and low resistance. The heart, pressure gradients, the peripheral venous pump, and competent valves interact together to overcome the hydrostatic pressure induced by gravity. The larger veins serve as the primary capacitance vessels where most of the blood volume is found and where regional blood volume is regulated. Venous stenosis is intimal hyperplasia and fibrosis causing progressive vessel narrowing and outflow obstruction. Venous stenosis most commonly affects the axillary, brachial, cephalic, or brachiocephalic veins of the upper extremities, or the superior vena cava, but can also affect the central veins in the abdomen and the pulmonary artery and veins. Common causes are placement of central venous catheters, pacemaker leads, hemodialysis catheters, prior radiation, trauma, or extrinsic compression. The use of venous stents is a medical necessity in patients with disabling or life-threatening occlusive or stenotic disease of the central veins that extend from the iliofemoral veins to the subclavian veins.
There are numerus prior art stenting applications for venous stenting. The most extensive clinical experience within venous stenting has been off-label use of the Wallstent (available from Boston Scientific). The Wallstent is available in large diameters and has an Elgiloy (similar to stainless steel) braided construction that provides flexibility. Unfortunately, because of the flexibility of the Wallstent, when constricted, its length varies resulting in decreased deployment accuracy. Accurate deployment is also limited by foreshortening of up to 40%. If there is compression near the end of the stent, as is often the case near the ilio-caval junction, the Wallstent may form a narrowed cone shape, which decreases flow, or the stent can migrate as it is squeezed away by a compressive lesion. Another pitfall of the Wallstent is in the setting of bilateral iliac stenting. In order to decrease problems with jailing of the contralateral side or narrowing of bilateral stents in the inferior vena cava, multiple techniques have been developed including the double barrel, fenestration, and Z stent techniques. Unfortunately, none of these techniques are ideal and may result in the need for reintervention.
The prior art also includes dedicated venous stents, many of which comprise self-expanding nitinol stents. For example, the Cook Zilver Vena venous stent has an open cell design and is available in 14-16 mm diameters and 60-140 mm lengths. The stent has a 7-French platform that is compatible with 0.035″ wires. The open cell design affords flexibility and the stent has minimal foreshortening. The Veniti Vici Venous stent, distributed by Boston Scientific, has a closed cell design with uniform end-to-end shape and strength. It is available in 12-16 mm diameters and 60-120 mm lengths. It has a 9-French platform compatible with 0.035″ wires. The closed cell design and sinusoidal strut rings give strength while the alternating curved bridges afford flexibility. It is a strong stent, with a sufficient surface area, performing well in May-Thurner syndrome patients, with good stent integrity. The Optimed sinus-Venous stent has a hybrid design trying to balance the need for both radial force and flexibility. The stent comes in 10-18 mm diameters and 60-150 lengths with a 10-French platform. With the sinus-Venous device, one has to be very accurate with the initial deployment because there is no change of repositioning. It is a flexible stent and with the correct deployment technique it also has a high crush resistance. The sinus-XL Flex stent is easier to deploy, though it is less flexible, and it has a tendency to kink at the flex points. The Optimed sinus-XL stent has a closed design affording high radial force. The stent comes in 16-36 mm diameters and 30-100 mm lengths with a 10-French platform. The sinus-XL in intended for large linear vessels including the aorta and the inferior vena cava. An Optimed sinus-XL 6 F also has been developed with diameters of 14 and 16 mm. Another stent, the Optimend sinus-XL Flex comes in large diameters (14-24 mm) but has an open cell design to afford it more flexibility. It comes in 40-160 mm lengths and also has a 10-French platform. The Optimed sinus-Obliquus has a hybrid design with a closed cell design oblique-shaped central end, an open cell design mid-segment, and an anchor ring at the peripheral end. The closed cell oblique segment allows for increased radial force and crush resistance at the iliocaval stress point while minimizing overlap of the contralateral common iliac vein. The open cell design of the mid-segment provides flexibility and conformity to the stent. The peripheral end anchor helps with stent fixation. The sinus-Obliquus stent, with its 10-Fr platform, comes in 14- and 16-mm diameters and 80-150 mm lengths. Medtronic has more recently initiated a dedicated venous stent investigational device exemption study, named the ABRE IDE study. The Abre venous self-expanding stent has an open cell design with 3 points of connection between cells to afford it flexibility and conformity. This stent system has a triaxial shaft design to aide with delivery. This device is delivered through a 9-Fr system and will be available in diameters up to 20 mm.
Despite the recent advance in the venous stenting field, still no ideal venous stent exists. The majority of the recently developed venous stents designs lacks several important features of a desirable venous stent. For example, most of the conventional venous stents are nitinol slotted tube designs that inherently lack adequate radial forces, equipped with connective struts to facilitate flexibility but these elements simultaneously make the structure vulnerable to outer forces, bringing in factors of long-term fatigue, etc. There is a real need to develop stents that feature the most requirements for an ideal venous stent.
Several self-expanding devices are described in U.S. Pat. No. 7,018,401 (“the '401 Patent”) and Pat. No. 8,739,382 (“the '382 Patent”), each incorporated herein by reference. Each of the '401 and '382 Patents provides a summary of some of the prior art relevant to the present disclosure, the prior art which is incorporated herein by reference.
The '401 Patent is directed to a self-expandable, woven intravascular device for use as stents, filters, and occluders for insertion and implantation into a variety of anatomical structures. The devices may be formed from shape memory metals such as nitinol, may be formed from a single wire, and may be formed by either hand or machine weaving. The devices may be created by bending shape memory wires around tabs projecting from a template and weaving the ends of the wires to create the body of the device such that the wires cross each other to form a plurality of angles, at least one of the angles being obtuse. In general, the proximal end of the straight stent is created by back-weaving the wire strands and then welding them at the appropriate points. As one example,
The '382 Patent is directed to a woven, self-expanding stent device that has one or more strands and is configured for insertion into an anatomical structure. The device includes a coupling structure (that is not a strand of the device) that secures two different strand end portions that are substantially aligned with each other. As one example,
Abbot offers a stenting system known as Supera. The instructions for use of the Supera Stent is publicly available and known to those of skill in the art and is incorporated herein by reference. The Supera Peripheral Stent System consists of a closed end, braided self-expanding stent made of nitinol (nickel-titanium alloy) wire material that is pre-mounted on a 6Fr delivery system. The stent typically does not include radiopaque markers, but to increase the radiopacity of the stent, the wire strands can be nitinol microtubings with a platinum core.
The Supera stent is a platform stent. In other words, the Supera structure allows the design of any size and/or length stent that is needed for the different vascular and non-vascular regions of the body, including the coronary artery. In general, any structure can be made from the appropriate number and size of wires to create a mesh that fits best given a particular anatomy's needs. For example, for coronary application, a Supera stent can be produced with a smaller number of wires than traditionally used: instead of twelve wires (six pairs), the stent may use six, eight, or ten wires to form the mesh. The mesh tightness can be adjusted according to the specific need, from open cell design to very tight mesh where the wire strands obtuse angles approaching 180 degrees. If a stent is made with a mesh size that is looser than the original design (that is the obtuse angles in the mesh are reduced), that will be the stent nominal diameter that is imprinted to the wires by the heat treatment. Such a stent may still feature a significant radial force what it is deployed with in nominal diameter.
The Supera stent sizes are labeled based on the outer stent diameter. A stent should initially be chosen such that its labeled diameter matches the reference vessel diameter (RVD) proximal and distal to the lesion. Final stent selection should be confirmed after lesion pre-dilation: if possible, the stent diameter should match the prepared lesion diameter 1:1. Due to the mechanical behavior of the woven Supera stent, the stent should not be oversized by more than 1 mm relative to the RVD. This ensures optimum deployment of the Supera stent, maximizing radial strength, and assisting in accurate stent length deployment. Choosing a labeled diameter to match the reference vessel diameter, then appropriately preparing the vessel to match that stent's diameter will result in a stent that is properly sized to the vessel. The vessel should be prepared utilizing standard angioplasty technique using a balloon size greater than or equal to the stent diameter. The post-dilated vessel should be at least the size of the stent diameter.
The Supera stent attempts to mimic the natural structure and movement of the relevant anatomy. The interwoven nitinol design creates a stent that supports rather than resists the vessel. By pre-dilating and matching the stent and vessel 1:1, the Supera stent supports the vessel with minimal chronic outward force. The Supera stent has increased strength and flexibility, with more than four times the compression resistance of typical standard slotted tube design nitinol stents. In severely calcified lesions, the Supera stent has visible compression resistance, maintaining a round, open lumen for normal, healthy blood flow in challenging anatomy.
The over-the-wire stent delivery system for Supera is compatible with a 0.014″ and a 0.018″ guide wire and comes in lengths of 80 cm and 120 cm (6Fr). The delivery system includes a reciprocating mechanism (e.g., stent driver) that incrementally moves the stent distally out of the outer sheath. This motion allows for the distal end of the stent to first come in contact with the targeted vessel, setting the distal reference point, and continues to feed the stent out of the sheath as the target wall is exposed by the proximal movement of the catheter. This stent deployment is achieved by the reciprocation of the thumb slide located on the handle. On the final stroke, the deployment lock is toggled, and the last deployment stroke is made.
A Supera based stent has a strong expansile (outward) force that can be easily adjusted by carefully selecting the size and the number of the wires for the mesh. The stent structure allows to create stents between a relative open cell arrangement and a very tight mesh size. The stent is biomimetic, that is, it can easily follow and accommodate to even the most tortuous anatomy while its inner diameter is never compromised. The Supera stent has perfect conformability. The Supera stent can withstand repeated pulsatile outer compressing forces, as well as axial movements (shortening/elongation) which is a factor in the coronary arteries on the surface of the ever-pulsating heart. The Supera stent is known to be able to endure very strong complex forces in the most challenging anatomy, namely in the femoropopliteal region. It can withstand compressive forces (popliteal artery), torque, shortening and elongation (femoral artery) even when these forces are present in combination. The stent may allow to eliminate the need for pre- and also post placement dilation, therefore its placement is much-much less injurious that that of the balloon expandable stent.
The Supera stent offers numerous benefits over other self-expanding stents and in particular balloon-expanding stents. In particular, Supera based coronary stents can overcome many of the inherent problems of balloon-expandable stents, such as high-pressure balloon inflations, overexpansion of a narrow segment distal to the stent, increasing the risk of an edge dissection, and underexpansion of a proximal segment resulting in poor stent apposition. Further, Supera based coronary stents eliminate the need for multiple very injurious balloon dilations and makes unnecessary the use of a DES coating that (while it has been proven to be advantageous to restrain neointima formation and increase lumen gain in the early phase of post-stenting) may result in patchy coverage of wire struts by neointima that can negatively influence in-stent restenosis in the long run. Self-expanding stents in general, and the woven nitinol stent in particular, embed deeply in the vessel wall reaching the muscular layer. As a result, the neointimal coverage can be complete. That is important to avoid in-stent restenosis later. Even a larger layer of the neointima will be adequately compensated by the fact that the stent making lumen gain after deployment for days or weeks. Still further, because balloon expandable stents cannot be used in vessels with a diameter larger than 4.5 mm, these lesions cannot be treated with them. The Supera based coronary stent's versatility in diameter and length allows treatment over a wide range of lesion sizes and configurations.
Conventional stents—whether balloon assisted or self-expanding—possess certain shortcomings that inhibit their ease and range of use. In particular, the dominant use of a balloon expandable stent in the coronary field is problematic, particularly in view that some self-expanding stents have several advantageous features over the balloon expanding counterpart. Self-expanding stents in general, and in particular a Supera based woven nitinol stent, provides several characteristics that make these stents more advantageous for the coronary application than the balloon expandable stents.
Despite the apparent benefits of a Supera based stenting system, it fails to address several problems and several characteristics of the different anatomical applications. The Supera stent is designed to be a robust stent, with excellent conformability, flexibility and crush resistance, which are the main requirements for a femoropopliteal stent. The femoropopliteal anatomy is the most challenging anatomy from a mechanical point of view. Because of the ambulation the femoropopliteal artery is exposed to extremely harsh and combined forces. These forces, which are repetitive in nature, are elongation/shortening, compression, torsion, and flexion, acting alone and/or in combination. The structure of the stent should be able to follow these movements and accommodate to them. These phenomena, which are aptly described as Supera's biomimetic characteristics, serve these purposes extremely well.
The woven stent design, however, is a platform stent, meaning that the basic structure of the stent allows for creating numerous different versions of the stent that are much more suitable to meet the special requirements of completely different anatomical locations. For example, for a coronary artery the robustness of the femoropopliteal Supera stent is not needed. Nevertheless, there are repetitive pulsating forces (on average 72/min) on the stents in that location that are very significant in the long run and necessitates a fatigue-free stent that does not break. Further, its radial force may be less with still excellent flexibility and conformability and these requirements can meet by structural modifications of the basic stent structure.
The use of an adequately modified woven stent for venous lesions may be another primary example. The arterial and venous anatomy are completely different structurally and hemodynamically, therefore the stents used in the arterial side are not able to meet the requirements of the venous locations. For example, the veins have much thinner walls with practically no muscle layer in it. A robust stent with high radial force would be completely inadequate in these locations; these stents would make the venous segments tube-like, rigid with undesired hemodynamic alterations. In addition, the venous wall would be exposed to extremely high forces that would be detrimental. In short, the woven stent design allows for numerous structural modifications that help find the stent with optimal characteristics for each of the different anatomical regions.
The statements in this section are intended to provide background information related to the invention disclosed and claimed herein. Such information may or may not constitute prior art. It will be appreciated from the foregoing, however, that there remains a need for an improved method, device, and system for treating ostial lesions and branching anatomies, particularly with self-expanding stents. A need exists for an improved method, device, and system for treating complex lesions including branching and bifurcated anatomies in the arterial system as well as the venous system. A need exists for a self-expanding stent and stent system that addresses problems such as high-level injuries of the balloon expandable stents, branching/bifurcated lesions, ostial lesions, and lesions with complex anatomy. A need exists for an improved self-expanding stent that provides for increased structural modifications and the ability to be used in a wide variety of applications. Such disadvantages and others inherent in the prior art are addressed by various aspects and embodiments of the subject invention.
This disclosure provides a self-expandable, woven intravascular device for use as a stent (both straight and tapered) in a variety of anatomical structures, including vessels in the arterial and/or venous system. The stent provides enhanced structural modifications to conventional woven stents by varying the wire(s) utilized in the woven stent. The stent may be formed from shape memory metals such as nitinol. The stent may utilize multiple, parallel wires instead of a single wire, an increased number of wire pairs and/or pins to vary the mesh size, and/or a bundle of wires (e.g., a plurality of individual wires coupled together) instead of a single wire. The individual wires may each be twisted to provide an overall twist to the wire bundle. The bundle of wires may comprise different sized wires and/or wires of different materials.
Disclosed is a self-expanding woven stent, comprising a plurality of shape memory wires woven together to form a body having a first end and a second end, wherein the plurality of shape memory wires comprises a first wire and a second wire, wherein the first wire is arranged substantially parallel to the second wire. Each of the wires may be substantially adjacent to each other, and may each comprise a wire bundle composed of a plurality of individual, smaller wires. Each of the plurality of shape memory wires may bend at a plurality of points creating a mesh of substantially perpendicular crossing wires that form a plurality of cells and a plurality of angles. The mesh formed by the crossing wires may be an open celled mesh or a closed cell mesh, thereby created by different weave densities of the crossing wires. In one embodiment, each of the plurality of angles are approximately 90 degrees, while in other embodiments the angles may comprise acute angles or obtuse angles.
The stent may have a flanged portion and a body that is tubular, substantially straight, and/or substantially tapered. The stent may be an arterial stent or a venous stent. The stent may be configured for deployment in at least one of the following arteries: coronary, iliac, femoropopliteal, infrapopliteal, carotid, vertebral, subclavian, and intracranial. The stent may be configured for deployment in at least one of the following veins: inferior vena cava, a superior vena cava, axillary, brachial, iliac, and femoral.
Disclosed is a self-expanding woven stent, comprising a body with a first end and a second end, wherein the body comprises at least one shape memory wire woven together, wherein the at least one shape memory wire crosses at a plurality of positions to form a plurality of cells and a plurality of angles, wherein the plurality of angles are approximately 90 degrees.
Disclosed is a self-expanding woven stent, comprising a body with a first end and a second end, wherein the body comprises at least one shape memory wire woven together, wherein the at least one shape memory wire comprises a wired bundle, wherein the at least one shape memory wire crosses at a plurality of positions to form a plurality of cells and a plurality of angles.
The wire bundle may comprise a plurality of individual wire strands, and they may be twisted together to form a generally helical wire. Each of the wire strands may be approximately the same diameter, or they may have different diameters. Each of the wire strands may have the same material or composition, or may be formed of different wire compositions. For example, the at least one wire bundle may have one or more microtubings with a platinum core. The wire bundle may have compressed wires, non-symmetrical wires, substantially compacted wires, and/or substantially round wires. The at least one wire bundle may comprise any number of individual wires, including at least three, at least seven, and at least 19 individual wires (or individual wire bundles).
The at least one wire bundle may comprise a plurality of individual wire segments, wherein at least one of the plurality of individual wire segments comprises an inner wire bundle. The at least one wire bundle may comprise a plurality of inner wire bundles, wherein each of the inner wire bundles comprises a plurality of individual wires. The at least one wire bundle may comprise a first plurality of wires with a first diameter and a second plurality of wires with a second diameter. The at least one wire bundle may comprise an inner set of wire bundles and an outer set of wire bundles. In one embodiment, the inner set of wire bundles may comprise a first set of wires with a first diameter and a second set of wires with a second diameter. In one embodiment, the outer set of wire bundles may comprise a first set of wires with a first diameter and a second set of wires with a second diameter.
Each of the individual wires of the stent may itself comprise a wire bundle formed of individual wire segments. Further, the stent may comprise a plurality of wires, and some or all of these may be wire bundles. For example, the at least one shape memory wire may comprise a plurality of shape memory wires, wherein each of the plurality of shape memory wires comprises a wire bundle to form a plurality of wire bundles for the stent. Each of these plurality of wire bundles may be substantially parallel and/or adjacent to each other. In one embodiment, each of the plurality of wire bundles comprises an inner set of wire bundles and an outer set of wire bundles. In another embodiment, the plurality of wire bundles comprises a first plurality of wire bundles with a first diameter and a second plurality of wire bundles with a second diameter.
Disclosed is a method for forming a self-expanding stent, the method comprising forming a stent by bending at least one shape memory wire at a first plurality of bends to form a mesh, wherein each of the plurality of bends is approximately 90 degrees and heat treating the at least one shape memory wire.
Disclosed is a method for forming a self-expanding stent, the method comprising forming a stent by weaving a plurality of shape memory wires together to form a body with a first end and a second end, wherein the plurality of shape memory wires is substantially parallel to each other. In one embodiment, the plurality of shape memory wires may be substantially adjacent to each other. The plurality of shape memory wires may comprise at least three wires. In other embodiments, the plurality of shape memory wires may comprise a plurality of wire bundles. Each of the plurality of shape memory wires may cross each other to form a plurality of cells and a plurality of angles. The angles may be approximately 90 degrees, may be acute angles, or be obtuse angles. In one embodiment, the method may further comprise bending the plurality of shape memory wires around a plurality of protrusions on a template.
In one embodiment, the disclosed stent is formed around a template with a plurality of protrusions. There may be a first plurality of pins at a first position and a second plurality of pins at a second position. The positions may be relative to each other, a radial position, and/or a longitudinal position. In one embodiment, the first plurality of pins is located at a first circumferential position on a template and the second plurality of pins is located at a second circumferential position on the template. In another embodiment, the second plurality of pins is located proximally on the template to the first plurality of pins. In one embodiment, the amount of the second plurality of pins is approximately half of the amount of the first plurality of pins, whereas in other embodiments the number of the second plurality of pins is greater than the first plurality of pins. In one embodiment, the second plurality of pins is substantially in-line with the first plurality of pins, while in another embodiment at least some of the second plurality of pins is located at an off position relative to the first plurality of pins. In one embodiment, the plurality of protrusions comprises a first plurality of pins located at a first circumferential position, a second plurality of pins located at a second circumferential position, and a third plurality of pins located at a third circumferential position.
Disclosed is a method for forming a self-expanding stent, the method comprising forming a stent by weaving at least one wire bundle together to form a body with a first end and a second end, wherein the at least one wire bundle crosses at a plurality of positions to form a plurality of cells and a plurality of angles. In one embodiment, the at least one wire bundle comprises a plurality of wire bundles. In one embodiment, the plurality of wire bundles is substantially parallel to each other and/or adjacent to each other. In one embodiment, the method further comprises twisting the at least one wire bundle during the weaving step. In another embodiment, the method comprises twisting a plurality of wire segments of the wire bundle together to form the at least one wire bundle.
The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.
Various features and advantageous details are explained more fully with reference to the nonlimiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known starting materials, processing techniques, components, and equipment are omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure. The following detailed description does not limit the invention.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
In one embodiment, disclosed is a self-expanding woven stent that provides enhanced structural modifications to conventional woven stents, such as a Supera based stent. In one embodiment, the disclosed stent varies the configuration of the wire(s) utilized in the woven stent to vary the characteristics of the stent. In one embodiment, the disclosed stent utilizes multiple, parallel wires instead of a single wire. In one embodiment, the disclosed stent utilizes an increased number of wire pairs and/or pins to vary the mesh size. In one embodiment, the disclosed stent utilizes a bundle of wires (e.g., a plurality of individual wires coupled together) instead of a single wire. In one embodiment, the individual wires may each be twisted to provide an overall twist to the wire bundle. In one embodiment, the bundle of wires may comprise different sized wires and/or wires of different materials. In one embodiment, some of the utilized wires may be micro-tubes filled with a radiopaque material, such as platinum. In one embodiment, the disclosed stent may be formed at least partially of biodegradable materials and may comprise a bioresorbable material.
The individual wires used in the stent may be metallic or non-metallic wire, which may include one or more twisted or woven filaments. The wire can take many different shapes, sizes, materials, and can have differential compositions and characteristics. For example, the wire may be round, flat, rectangular, oval, triangular, serrated, and other configurations, and may be symmetrical or non-symmetrical (e.g., compacted). In other words, a wire is not necessarily round or symmetrical. Similarly, the wire may be tubular or solid, as well as cored or woven. The material, shape, and diameter of the wire is variable based upon various desired characteristics of the stent and the intended stent application.
The disclosed stent provides numerous benefits. For example, the proposed wide scale of modifications for the disclosed stent make it possible to find the best mechanical characteristics for a dedicated anatomical location. The disclosed stent allows for a wide range of stent optimization that provides the best possible acceptance, integration, and/or incorporation of the stent as a foreign body by the living structure. While the general characteristics of the woven design such as flexibility, conformability, and/or crush resistance will remain, they may be fine-tuned (optimized) with properly selected radial force, adequate mesh tightness (closed cell vs. open cell designs), and fatigue-freeness, among other capabilities.
In one embodiment, the disclosed stent varies the type of utilized wire(s) of the stent, as the wire caliber has a significant impact on the strength of the stent and other properties (such as radial/expansile force, crush resistance, and hoop strength). For example, if the size of the nitinol wire is increased, different characteristics of the stent may proportionally increase. As another example, if more wires are utilized in the stent structure, the overall coverage of the stent increases as well as the increase of the angles of the crossing wires resulting in a tighter wire mesh (also resulting in an overall increase in strength). For some applications, the stent coverage is very important, as it dictates whether an open cell or closed cell stent design is used, as well as whether the stent is suitable for a particular application (e.g., in a carotid artery application or in the venous system). In other applications, certain modifications may result in a desired decrease in strength of the stent to achieve the best match/design between the stent and the given anatomical structure.
In one embodiment, the disclosed self-expanding stent allows it for being used as a platform stent. In other words, the disclosed stent can be used to produce stents that are suitable for use essentially anywhere in the body. The disclosed stent can be used in the vascular system (e.g., arterial and venous stents) or the non-vascular system (e.g., biliary tree, colon, etc.). The disclosed stent also provides for a wide range of sizes, including for large diameter stents (aorta, vena cava) or very small caliber stents such as coronary and intracranial stents. In short, the various anatomical territories with a given body requires different stents that best suit the particular structure and function. The basic structure of the disclosed stent offers several ways to meet the requirements of the various anatomical structures. As another example, the disclosed stent may be used alone or be part of a modular stent assembly in which a plurality of stent portions may be coupled together after placement within an anatomical body. Furthermore, the disclosed stent can be configured with different mesh tightness, radial force, diameter, and length as well as taper, each of which may fit a wide variety of anatomical structures all over the body. In one embodiment, the variability in the mesh tightness, the number, and the size of the wires used to create the mesh offers limitless variations that serves the goal to produce the ideal stent for various applications.
In one embodiment, the disclosed stent is a self-expanding stent as opposed to balloon expandable stents typically used in the prior art. Balloon expandable stents require a series of balloon dilation to achieve the desired lumen gain and stent-strut apposition in the vessel. Typically, these balloon inflations are performed before, during, and post deployment of the stent. Not infrequently, each phase uses several balloon inflations. In general, each balloon inflation overextends the vessel wall by at least 10-20 percent to offset the vessel's elastic recoil. The repeat balloon inflations are overtly injurious and as a result the vessels inner layer (endothel) reacts with abundant production of neointima. This thick neointima does not only cover the stent struts but its bulkiness restricts the lumen causing luminal loss (in-stent restenosis). For these reasons, the balloon expanding coronary stents have recently been using with drug eluting systems (DES) to counterbalance the neointima proliferation. Although the antimitotic drugs can efficiently block the neointimal formation and thereby the in-stent restenosis, it may create a patchy intimal layer coverage in the long run, which in turn may lead to a chronic in-stent restenosis with luminal loss. The DES systems are already in their third generation but minimizing the injuriousness on the vessel wall by using self-expanding stents with optimized mechanical characteristic would be the ideal solution.
Self-expanding stents in general, and in particular a Supera-based woven nitinol stent, provides several characteristics that make them more advantageous for coronary applications than prior art balloon expandable stents. For example, the disclosed self-expanding stent has robust redial forces that are even throughout the stent length, has excellent conformability even in the most tortuous vasculature without compromising its lumen, is crush-resistant, and can withstand tens of millions of pulsating forces without a break. In addition, the disclosed stent design allows for creating stents with physical characteristics which are ideal for the given type of vasculature. As another example, deployment of the disclosed self-expanding stent is much less injurious than balloon expandable stents, and there is no need to use balloon inflations to get an appropriate apposition to the vessel wall. As another example, the self-expanding stent has much better conformability and is able to adapt to the given anatomical situation as compared to balloon stents (which generally straighten the stented segments because the balloon itself is not flexible). In particular, the mechanism of post dilation of the balloon expanding and the self-expanding stent is different; whereas the balloon expanding stent requires significant over-dilation of the vessel to achieve the appropriate apposition, the disclosed self-expanding stent inherently withstands any over-dilation, that is, the inflation of the balloon only facilitate the stent to take on its maximum diameter. In one embodiment, if the disclosed stent size is determined precisely according to the diameter of the vessel, any possibility of over-dilation of the self-expanding stent is eliminated. The disclosed self-expanding stent can overcome many of the inherent problems of balloon-expandable stents, such as high-pressure balloon inflations, overexpansion of a narrow segment distal to the stent, increased risk of an edge dissection, and underexpansion of a proximal segment resulting in poor stent apposition. Limitations of self-expanding stents in general include difficulty with precise placement (foreshortening), especially in ostial lesions, and inability to oversize the stent beyond its “set” diameter. These prior art stents, being bulkier, may also be difficult to deliver.
Body 201 may have a substantially tubular shape, uniform shape, or a substantially tapered shape, among other configurations. In one embodiment, body 201 may be formed of a plurality of wires 211 that are woven together to form a mesh or grid body for stent 200. A plurality of wires may be used to form the mesh, such as two, four, six, eight, ten, or twelve or more wires. As is known in the art, the size, diameter, and number of wires 211 may be changed to produce the desired configuration and characteristics of stent 200. In one embodiment, the mesh tightness can be adjusted according to the specific need, from open cell design to closed cell design, straight or tapered design, and with or without metallic materials. In one embodiment, the mesh density is variable and/or different between different portions of the stent. For example, a first portion of the stent may be woven with a tighter mesh than a second portion of the stent, that is, the obtuse angles between the wire strands are increased. Alternatively, a particular stent portion can be woven with a looser mesh size, that is the obtuse angles between the wire strands are decreased. These variations in the weave may result in optimal construction of the stent depending on the application and relevant anatomical structure. Thus, the mesh tightness, the radial force, the stiffness and the flexibility of the stent can be set in a very wide range, thereby providing a mesh (and resulting stent structure) offers the ideal stent for the particular anatomy.
In one embodiment, body 201 comprises leading or distal end 203 and trailing or proximal end 205. Wires 211 may be shape memory (e.g., nitinol or other similar shape memory wire) and be bent approximately at their mid-portion, thereby forming wire pairs. End 203 may have a plurality of closed structures 221. These closed structures may be small closed loops 6 or bends 8 (see
As described in the '401 Patent and the '382 Patent, the disclosed stent may be formed by either hand or machine weaving a plurality of individual wires, filaments, and/or strands together. For example, as is known in the art, the stent may be created by bending shape memory wires around tabs projecting from a cylindrical template, and weaving the ends of the wires to create the body of the device such that the wires cross each other to form a plurality of angles. In general, the proximal end of the straight stent is created by back-weaving the wire strands and then welding them at the appropriate points as seen in
In one embodiment, the self-expanding nature of the disclosed stent allows the stent to expand against the plaque in the artery and exert an outward radial force that resists compression. The greater the density (e.g., the more it is a closed cell stent), the greater radial force the stent exerts on the artery. However, excessive radial force can cause stent impaction and plaque protrusion; the dense mesh in turn will prevent plaque protrusion from occurring. In some embodiments, a portion of the stent is partially or substantially tapered (instead of substantially straight). For example, tapered designs can be useful when deploying stents across the carotid bifurcation, as the common carotid artery (CCA) is typically larger than the internal carotid artery (ICA). The tapered design means that the maximum diameter at the proximal end is larger than that of the distal end, better matching the calibers of the CCA and the ICA, respectively. In one embodiment, tapered stents can have a gradual, conical taper or a more abrupt, shouldered taper. Other examples may be aorto-iliac and ilio-femoral transition in the arterial side and ilio-caval transition in the venous side.
The disclosed stent may be considered as a bare-metal stent. It may partially or substantially be constructed of nitinol, and may or may not comprise a metal, metal alloy, and/or biodegradable material. For example, combining nitinol with any number of core materials may provide a nitinol composite with significantly increased properties (such as radiopacity, conductivity, or resiliency) while still maintaining its elasticity. Various materials may be paired with nitinol for portions of the disclosed stent, including but not limited to stainless steel, nickel, titanium, gold, platinum, tantalum, palladium, and alloys thereof.
In one embodiment, based on the arterial version of the nitinol woven stent (e.g., SUPERA), the stent should be modified according to the special requirement of the intended anatomical body (e.g., arterial, venous, etc.). For example, there are several ways to achieve the ideal radial force/hoop strength for the venous stents. In some instances, however, excellent expansile force is a must (e.g., under the inguinal ligament or the treatment of the May-Turner syndrome). Careful selection and combination of the diameter of the nitinol wire strands, the number of wire strands used for the structure, and angle between the crossing wires offer plenty of possibilities to find the ideal strength. Simultaneously, the stent's other characteristics can also be modified according to the needs of the special application. For example, the woven structure allows for creating a closed cell design or an open cell design and any version in between.
In still other embodiments, the stent may utilize more than two parallel wires. For example,
As discussed above, the weave structure of the stents may be varied. For example, the distance between adjacent parallel wires may be increased or decreased. As another example, the angles between the crossing wires may be increased or decreased. For instance, the angles illustrated in
In one embodiment, using multiple parallel wires for the disclosed stent as mentioned above allows for using smaller caliber (e.g., weaker) wires. This is beneficial for multiple reasons. For example, the weaker wires may result in a decreased expansile force of the stent. This feature can be used when a robust radial force or crush resistance is not needed (e.g., in some locations in the venous system a weaker expansile force is desired). In one embodiment, the decrease in the radial force can be partially compensated by the multiple crossings of the multiple wires. In another embodiment, the coverage of the stent and/or the mesh angle can also be adjusted according to the requirements of the given anatomy. For example, a close cell mesh (e.g.,
In one embodiment, the disclosed stent may utilize an increased number of wire pairs and/or pins to vary the mesh size. In one embodiment, additional pins may be arranged circumferentially or vertically on a cylindrical template for formation of the stent. In one embodiment, the additional pins are positioned on the same level of the template around a circle. Consequently, the total number of wires that form the mesh can be increased. For example, instead of using 6 wire pairs (12 wires), one can use 8 pairs (16 wires), 10 pairs (20 wires), or even 24 pairs (48 wires), as well as any other reasonable number of pairs/wires to form the mesh. Another possibility is that the additional pins are positioned below the original pins to form a second circle. This variation will result is a slightly decreased radial force at the end of the stent where the mesh is formed on only the first (outer) circle of pins. Thus, the mesh tightness will be much looser here. The number of wires in this latter arrangement may vary in a wide range. All these modifications serve the same goal to create the most optimal physical characteristics of the stent for the given anatomical structure.
In one embodiment, the disclosed stent may utilize a bundle of wires (e.g., a plurality of individual wires coupled together) instead of a single wire. The bundle of wires may comprise different sized wires and/or wires of different materials. In one embodiment, rather than using a single filament or wire strand, a wire rope and/or wire bundle may be formed of a plurality of individual wire strands that are coupled together.
A bundle of wires instead of a single wire provides numerous benefits. For example, if one of the plurality of wires fails, the other wires can easily take up the load. Thus, any flaws in an individual wire is not as critical as compared to looking at the bundle of wires as a whole. A bundle of wires also prevents fatigue of the single individual wire, similar to the principle of rope wires (which use braided strands of individual rope filaments). This embodiment is valid for woven stent designs and not for prior art slotted tube stents. This type of stent is particularly useful for stents used in femoropopliteal arteries as well as generally venous stents, which require a longer life expectancy of the stents and increased repetitive forces leading to fatigue. In the case of venous applications, the stent's life-expectancy and fatigue-freeness is a critical issue because venous diseases require stent placements at a much younger age in comparison with arterial applications (arteriosclerosis). Therefore, the venous stents should serve without failure for 40-50 years compared to the 5-20 years for the arterial stents. The prior art arterial stents and even the recently developed specific dedicated venous stents have not proven themselves in that regard. The potential for failure in encoded into the structure of these stent: the slotted tube designs are inherently inferior because their flexibility is achieved by creating connecting elements (bridges) that in turn make the stents extremely vulnerable and prone to fracture in the long run.
There are numerous design variations of a wire bundle that can be used in a woven stent, depending on the intended stent configurations, application of the stent, and anatomical location in which the stent is to be deployed. For example, some of the wires may be different shapes and/or sizes, while some of the wires may be different materials. Following the principle of the wire rope, virtually endless variations of a wire bundle can be created that can be used as individual wire strands for a woven stent.
As is known in the art, the diameter of the wire used for a woven structure determines the size of the delivery system. The delivery system of a stent consists of an inner and an outer catheter. In one embodiment, the outer diameter (OD) of the delivery system can be described by using the following equation: OD total=OD inner catheter+4× wire diameter (assuming two crossing wires are on both sides of the inner catheter)+wall thickness of the outer catheter. Thus, reduction of the wire diameter greatly decreases the needed diameter of the delivery system. However, in general, conventional wires cannot be decreased significantly without materially impairing the strength of the wire strand and the overall stent. In one embodiment, utilizing wire bundles instead of individual wire strands allows the overall wire thickness to decrease, which among other benefits, reduces the overall diameter of the delivery system needed.
Another embodiment on reducing the diameter of the wire bundle is to make the wire bundle/rope in a compacted fashion.
In one embodiment, the wire bundle may be a twisted and/or helical wire bundle.
In one embodiment, the wire bundle may comprise an inner set of wire bundles and an outer set of wire bundles in various complex shapes and/or configurations.
In one embodiment, the disclosed stent may be a bioresorbable stent. In general, a bioresorbable stent has the capability to degrade within six to twenty-four months within the body. They can be used as a temporary scaffold and no material is left behind after they degrade (in contrast to metal stents). In general, bioresorbable vascular scaffold (BVS) technology has been used in the coronary arterial system. Scaffolds have been either polymer-based or metallic-based. The most common polymer-based scaffold is made from poly-L lactic acid, the material used in absorbable sutures and biologic implants. Bioresorbable scaffolds provide vessel support and potential antiproliferative drug delivery. Theoretically, their ability to absorb over time improves vessel conformability and potentially may restore the vessel to its physiologic state. Bioresorbable scaffolds offer less concern of jailing side branches, and there would be a decrease risk of late stent fracture and late stent thrombosis. Also, the scaffold would have less magnetic resonance and computed tomography imaging artifact.
The Absorb BVS (offered by Abbott Vascular) is one type of bioresorbable stent/scaffold, but studies have shown various adverse effects include thrombosis. Technical concerns of Absorb BVS deployment included difficult delivery of the system due to thickness and maneuverability in small tortuous arterial vessels, difficult visualization despite presence of platinum radiopaque markers, need for adequate predilation to allow for full scaffold expansion, recoil after expansion, and inability to over-dilate due to scaffold damage.
In one embodiment, the disclosed wire bundles (e.g., coupled/stranded wire filaments instead of a single wire) can be used to make various stents (such as the Absorb BVS stent) more resistant to overdilation based on the wire bundle principles disclosed herein. Using the wire bundles, the tensile strength of the overall wire bundle is significantly increased as compared to a similar sized individual wire. The wire/filament bundle is stronger than the individual strut and if it is made in a compacted fashion (see, e.g.,
In one embodiment, the angles in the wire mesh of the disclosed stent can be varied on a wide scale from a very compact mesh tightness (such as where the axially oriented angles approaching 180 degrees) to a very open cell design (which may have axially oriented angles less than 90 degrees). For example, the angles illustrated in
In one embodiment, the disclosed stent may utilize crossing wires that form an angle of approximately 90 degrees. In contrast, the conventional Supera stent has a woven structure that has obtuse angles. See, e.g., the '401 Patent. For example,
In one embodiment, the angles of the stent mesh provide various groups based on the angle sizes. For example, a first stent group (the “acute angle group”) may have axially oriented angles that are less than 90 degrees. In one embodiment, the angles may be at least 60 degrees, and may be greater than 60 degrees and less than 90 degrees. In some embodiments, the angle may be less than 60 degrees. A second stent group (the “obtuse angle group”) may have axially oriented angles that are greater than 90 degrees. In one embodiment, the angles may be at least 90 degrees and less than 180 degrees. A third stent group may have axially oriented angles that are approximately 90 degrees.
These embodiments can be reproduced by using substantially cored/solid wires and/or bundled wires. In one embodiment, all of the wires are bundled, while in other embodiments one or more of the wires may be bundled. Other variations exist, and the same stent structure may comprise differently structured wire bundles (both in shape, material, size, configuration, etc.). In one embodiment, each of the embodiments illustrated in
In one embodiment, the deployment of the disclosed stent follows the principle of the Supera woven stent. For example, it uses a reciprocal mechanism that deploys the stent incrementally. These stents may be stackable, meaning their mesh tightness can be increased during deployment, which is a particularly advantageous feature where the radial force of the stent should be increased locally (such as places where heavily calcified lesions are present). Because the stent deployment is performed by releasing a small increment at a time, the phenomenon of foreshortening is completely eliminated. The repositionability that the delivery system offers makes it easy to correct any malposition of the stent and allows for complete withdrawal of the partially deployed stent back to the delivery catheter. Further, after correcting the position of the delivery system the stent deployment can be repeated.
The disclosed stent may be inserted and deployed in a variety of manners. Similar to the deployment of a Supera based stent, the disclosed stent may be used with a guidewire and delivery catheter. In one example, the size of the delivery catheter may be a 5F, 6F or 7F catheter. Other sizes are possible: for example, for venous stents the delivery system may be 8F-10F. In one embodiment, the disclosed stent may be delivered similar to that described in U.S. Pat. Nos. 8,876,881 and 9,023,095, each incorporated herein by reference.
In one embodiment, the disclosed stent provides deployment capabilities without foreshortening. For example, during deployment, the distal part of the woven nitinol stent anchors firmly itself within the given vascular structure. As the deployment continues more and more length of the stent is getting contact to the vessel wall. In one embodiment, the stent is stackable, that is, the subsequent portions of the stent are deployed continuously behind the already deployed ones. Thus, at the very end of the deployment there is no jump when the very end of the stent exits from the delivery catheter.
All of the methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the apparatus and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. In addition, modifications may be made to the disclosed apparatus and components may be eliminated or substituted for the components described herein where the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the invention.
Many other variations in the system are within the scope of the invention. For example, the disclosed stent may or may not be deployed by itself. The stent may be substantially straight, conical, and/or tapered, and may have a flanged portion on one end of the stent. In some embodiment, the disclosed stent may be an integral part of one or more stenting systems (whether flanged or straight), and thus may be considered a modular flange system. The disclosed stent may be used in any anatomical structure and is not limited to branching vessels. The disclosed stent may be used in arterial systems and/or venous systems. The disclosed stent may be formed of individual wire strands and/or wire bundles. The wires utilized in the stent may be twisted. The disclosed stent may be formed of a single continuous wire (or wire bundle) or a plurality of wires (or wire bundles). While nitinol may be one shape memory wire used, a variety of other shape memory materials may similarly be utilized. It is emphasized that the foregoing embodiments are only examples of the very many different structural and material configurations that are possible within the scope of the present invention.
Although the invention(s) is/are described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention(s), as presently set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention(s). Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.
Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The terms “coupled” or “operably coupled” are defined as connected, although not necessarily directly, and not necessarily mechanically. The terms “a” and “an” are defined as one or more unless stated otherwise. The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more elements possesses those one or more elements but is not limited to possessing only those one or more elements. Similarly, a method or process that “comprises,” “has,” “includes” or “contains” one or more operations possesses those one or more operations but is not limited to possessing only those one or more operations.
This application claims priority to U.S. provisional patent application no. 62/716,035, filed on Aug. 8, 2018, the entire contents of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62716035 | Aug 2018 | US |
