Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2/013—Distal protection devices, i.e. devices placed distally in combination with another endovascular procedure, e.g. angioplasty or stenting
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
  • A61F2/962—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve
  • A61F2/97—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve the outer sleeve being splittable
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/01—Filters implantable into blood vessels
  • A61F2002/018—Filters implantable into blood vessels made from tubes or sheets of material, e.g. by etching or laser-cutting
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/95—Instruments specially adapted for placement or removal of stents or stent-grafts
  • A61F2/962—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve
  • A61F2/966—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod
  • A61F2002/9665—Instruments specially adapted for placement or removal of stents or stent-grafts having an outer sleeve with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod with additional retaining means
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0067—Three-dimensional shapes conical

Definitions

• Implants such as stents and occlusive coils have been used in patients for a wide variety of reasons.
• One of the most common "stenting" procedures is carried out in connection with the treatment of atherosclerosis, a disease that results in a narrowing and stenosis of body lumens, such as the coronary arteries.
• a balloon is typically dilatated in an angioplasty procedure to open the vessel.
• a stent is set in apposition to the interior surface of the lumen in order to help maintain an open passageway. This result may be affected by means of scaffolding support alone or in coordinated use with one or more drugs carried by the stent to aid in preventing restenosis.
• self-expanding prosthetic devices need not be set over a balloon (as with balloon-expandable designs), their delivery systems can be designed to a relatively smaller outer diameter than balloon-expandable counterparts. As such, self-expanding stents may be better suited to reach the smallest vasculature or achieve access in more difficult cases.
• an outer sheath restraining a stent overrides an inner tubular member.
• the tubular member has a lumen adapted to receive a guidewire and a distal end adapted to abut the stent for delivery.
• a system capable of such use is also described in USPN 4,580,568 (Gianturco) in which a sheath overrides a polymeric tubular member.
• USPN 6,280,465 discloses a very similar system.
• the device described in connection with Fig. 4 includes a central guidewire member, over which a tubular sheath and pusher are disposed.
• the guidewire/pusher/sheath combination is advanced to a treatment site within a guiding catheter as an integral assembly.
• the ability to mount the stent and its retention means to any guidewire is expressed as desirable.
• Unit preassembly is also discussed as advantageous for time savings.
• USPN 6,042,589 discloses a stent delivery system for employing a sheath/pusher type arrangement with the addition of an expandable balloon element for stabilizing the proximal end of the stent as the distal end of the stent opens concurrent with sheath withdrawal.
• the inclusion of the balloon further compounds the difficulty one would face in miniaturizing such a system.
• SMA Nitinol retains a deformed shape until the alloy is heated to thermodynamically drive a phase transition that restores the undeformed shape.
• SE Nitinol can be flexed and will return immediately to shape upon release, springing back from strain of up to about 8%.
• stent expansion occurs progressively/concurrently with sheath removal.
• Nitinol stents are self-expanding SE Nitinol stents. They open to the greatest extent possible when confined in a restraining member such as a sheath. Stated otherwise, a SE stent forces/strains against its confining member.
• a stent employing SMA properties for self-expansion will remain in a collapsed state until heat-activated to drive it open.
• the '156 publication is believed to illustrate such a situation.
• the publication shows the stent set well inside its available envelope as defined by the inner wall of the sheath prior to stent delivery. That is, with stent delivery system in its pre-deployment configuration, a substantial gap exists between the outside of the stent and the inside of the sheath.
• the marker/blocker features on the guidewire core member are set a substantial distance apart from the wall of the sheath.
• the blocker arrangement and stent/sheath gap illustrated are consistent with the other teachings of the ' 156 publication directed to SMA Nitinol stents.
• stents relying on shape memory alloy (SMA) thermally-driven shape recovery/change to open can be disadvantageous for reasons ranging from unpredictable deployment (due to even small variations in A f , n i sh temperature, for reason of inadvertent heating during deployment, etc.) to a requirement that environmental controls be employed in device storage. Accordingly, there continues to be interest in developing space-efficient elastic or superelastic stent delivery systems. The present invention addresses this interest and offers other advantages as will be appreciated by one with skill in the art in view of the following disclosure.
• SMA shape memory alloy
• a delivery guide system for use in delivering an implantable device to within the body.
• the subject systems are particularly useful for delivery and deploying a stent within the vasculature.
• the delivery guide system includes a corewire that can be used as a guidewire subsequent to implant delivery..
• the corewire-turned-guidewire advantageously comprises a commercially available guidewire, a clone of such a wire or one offering comparable performance.
• the member is tapered from a larger diameter at a more proximal end to a smaller diameter at a distal end up to an optional coil tip for use in tortuous or otherwise difficult to access anatomy.
• the "taper" may be a continuous taper or taper/step-down in size over sections.
• the corewire provides additional functions or carries components in addition to the stent.
• the corewire may provide a filter device (e.g., an embolic filter) which is usable prior to (e.g., during an angioplasty procedure), during and/or after stent deployment.
• the corewire may further include radiopaque markers at selected locations along its distal length to demark, for example, the very distal tip, the filter location and/or the stent location.
• the present invention provides a delivery system that may have a distal diameter of about 2 Fr (about 0.022 to 0.026 inch) or less and is adapted to deliver elastic/superelastic self expanding stents.
• the guidewire core member of the device preferably has a 0.014 to about 0.018 inch crossing profile, hi this way, once the corewire is freed for use as a guidewire, it can be used with standard balloon catheter and microcatheter components.
• An inner sleeve or tubular member is provided over the corewire/guidewire.
• An outer sleeve or tubular sheath is provided to restrain one or more stents carried by the delivery device.
• the inner sleeve serves to fill space between the guidewire core and external sheath.
• the inner sleeve may also serve in coordinated use with a raised feature on the corewire as a combination stent stop, blocker or abutment interface.
• An advantage of the combined sleeve/core feature is that it offers a relatively smaller diameter "bump" on the guidewire.
• a larger stop/blocker feature is required in instances where the inner sleeve stops short of the blocker feature, since that feature must - alone - offer a sufficient stop or abutment surface to stabilize the elastic or superelastic self-expanding stent for delivery.
• the raised stop feature may be a band connected (glued, welded, etc.) to the guidewire, a step or shoulder integral with the guidewire or be otherwise provided.
• the raised stop feature comprises a solid body of unexpandible or at least substantially non-compressible material (e.g., it is not a balloon, gel or other compliant material) such as metal, plastic or a relatively high durometer electrometric material. It is a member designed to serve its function while occupying a minimal amount of space and/or have a minimal impact on the sizing of adjacent structure (e.g., it has no lumen leading thereto). Whether the raised feature has a scalloped shape, a perforate body or another physical form, it must offer a surface to abut and stabilize at least a portion of a proximal side of the stent.
• the raised feature will have a diameter between about 0.0015 and about 0.010 inches greater than that of an adjacent stent-side section of the corewire where the stent is received in the delivery system.
• the raised feature In a system employing about a 0.014 inch guidewire core, the raised feature is generally about 0.0015 to about 0.0025 inch "tall"; in a system using about an 0.018 inch guidewire core, the raised feature is generally about 0.002 to about 0.005 inch tall; and in a system using a guidewire core of about 0.022 inch or larger, the raised feature is generally about 0.005 to about 0.010 inch tall.
• each of the inner and outer sleeves may be removed.
• the stent abutment feature With the device utilizing the combination blocker approach, the stent abutment feature then has a profile which is low enough so that it does not interfere with subsequent use of the core member as a fully functional guidewire. In this manner, a balloon catheter or another member can be advanced over the core member after removal of the other system components.
• a ramp is advantageously provided on the proximal side of the feature to provide an improved transition.
• Optional medical procedure steps to be accomplished after stent delivery may include maintaining wire position while advancing another stent delivery system over the wire (specifically an over-the-wire delivery system different than the systems described herein), advancing a balloon catheter for a post-dilatation step, navigating to a new treatment site, etc.
• the corewire still offers certain utility.
• the wire may be advanced so that the blocker is distal to the stent delivered and next advancing a balloon catheter to effect post-dilatation at the lesion site.
• the tubular members are split or splitable. If the inner member is pre-split or includes perforations or other features to aid in splitting open the sleeve, the open or perforated, etc. length will generally terminate within about 5 to about 15 cm of a distal end for the sake of stability or component strength at the end of the device that interfaces with the stent. The same may be true of the distal section of the outer tubular member. With a pre-split inner member, (either fully or partially), the system relies on the outer member to hold the components together. In another example, the handle used in the system includes a blade or wedge member to cut or assist in opening the sleeves as they are pulled through the handle.
• the sleeves may instead be withdrawn proximally up to a point where any closed portion remains over the guidewire/corewire.
• a physician may then switch his grip from a proximal location to the sleeve portions, to distal of them - even with a wire between about 150 and about 180 cm in length.
• a longer 300 cm "exchange length" wire or “dock” type system could be used to provide an overall length that allows the sleeves to be withdrawn clear of the wire while holding a proximal portion of the device/assembly.
• the option of removing the inner and outer sleeves from the corewire of the device offers a physician a bare wire (upon optional handle removal) for use in a vessel without altering or disturbing a distal position of the wire.
• the wire starts out as an integral part of the delivery system. As such, it is specifically sized for optimal use with the other components and includes those blocker/stop features noted above. Such construction lends itself to providing a system that is torquable en masse and/or one in which the corewire can be set to be spun/rotated within the sleeves to specifically direct the tip.
• the present invention includes systems comprising any combination of the features described herein. Methodology described in association with the devices disclosed also forms part of the invention.
• Such methodology may include that associated with completing an angioplasty, bridging an aneurysm, deploying radially-expandable anchors for pacing leads or an embolic filter, or placement of a prosthesis within neurovasculature, an organ selected from the kidney and liver, within reproductive anatomy such as selected vas deferens and fallopian tubes or other applications.
• stent refers to any coronary artery stent, other vascular prosthesis, or other radially expanding or expandable prosthesis or scaffold-type implant suitable for the noted treatments or otherwise.
• exemplary structures include wire mesh or lattice patterns and coils, though others may be employed in the present invention.
• a "self-expanding" stent as used herein is a scaffold-type structure (serving any of a number of purposes) that expands from a reduced-diameter (be it circular or otherwise) configuration to an increased-diameter configuration by elastic or pseudoelastic recovery in response to removal of a restraining member. Accordingly, when held by the restraint, the stent strains or presses against the inner wall of the restraint structure. As such, neither the alloy nor the delivery system is configured so that the stent will retain its shape within the body without restraint. In other words, where an alloy such as Nitinol is used in a stent according to the present invention, its Ag n i sh temperature is at body temperature or below (i.e., less than or equal to about 37 degrees C.)
• a "wire” as used herein generally comprises a common metallic member.
• the wire may be coated or covered by a polymeric material (e.g., with a lubricious material such as TEFLON ® , i.e., PTFE or PolyTetraFlouroEthelyne) or otherwise.
• the "wire” may be a hybrid structure with metal and a polymeric material (e.g., VectraTM, SpectraTM, Nylon, etc.) or composite material (e.g., carbon fiber in a polymer matrix).
• the wire may be a filament, bundle of filaments, cable, ribbon or in some other form. It is generally not hollow.
• a "guidewire” or “corewire” as used herein generally comprises member tapered or stepping down from an enlarged proximal diameter to a reduced distal diameter. It generally terminates in an atraumatic tip that may have a diameter equal to or greater than a proximal section of the wire.
• the dimensions and relative length and location of the two or more different diameter sections, tapers between them, as well as the parameters (length, angle, etc.) may vary.
• material selection may vary.
• a 0.014 inch wire has a proximal shaft of about a 0.014 inch diameter, a reduced diameter distal section of about a 0.010 inch diameter and a coil tip having about a 0.014 inch diameter.
• hypotube refers to hypodermic needle tubing or other small diameter tubing in the size range discussed below, generally with a thin wall.
• the hypotube may specifically be hypodermic needle tubing. Alternatively, it may be wound or braided cable tubing, such as provided by Asalii Intec Co., Ltd or otherwise.
• the material defining the hypotube may be metallic, polymeric or a hybrid of metallic and polymeric or composite material.
• An "atraumatic tip” may comprise a plurality of spring coils attached to a tapered wire section. At a distal end, the coils typically terminate with a bulb or ball that is often made of solder. In such a construction, the coils and/or solder is/are often platinum alloy or another radiopaque material. The coils may also be platinum, or be of another material. In the present invention, the wire section to which the coils are attached may be tapered, but need not be tapered. In addition, alternate structures are possible. For instance, molding or dip-coating with a polymer may be employed. In one example, the atraumatic tip may comprise a molded tantalum-loaded 35 durometer PebaxTM tip. However constructed, the atraumatic tip may be straight or curved, the latter configuration possibly assisting in directing or steering the delivery guide to a desired intravascular location.
• Radiopaque markers are understood to be markers or features of the various delivery system components, corewire or implant that may be employed to facilitate visualization of the system components.
• various platinum (or other radiopaque material) bands, coatings or other markers may be variously incorporated into the system.
• the stent may be made of radiopaque material or incorporate them. Especially where the stent employed may shorten somewhat upon deployment, it may also be desired to align radiopaque features with the expected location (relative to the body of the inner member) of the stent upon deployment.
• a filter used with the subject devices may also be made of radiopaque material for the same reasons.
• connection refers to fusing, bonding, welding (by resistance, laser, chemically, ultrasonically, etc), gluing, pinning, crimping, clamping or otherwise mechanically or physically joining, attaching or holding components together (permanently or temporarily).
• Fig. 1 shows a heart in which its vessels may be the subject of one or more angioplasty and stenting procedures
• Fig. 2A shows an expanded stent cut pattern as may be used in producing a stent according tc first aspect of the invention
• Fig. 2B shows a stent cut pattern for a second stent produced according to another aspect of the present invention
• Fig. 3 A shows an expanded stent cut pattern as may be used in producing a stent according tc first aspect of the invention
• Fig. 3B shows a stent cut pattern for a second stent produced according to another aspect of the present invention
• Figs. 4A-4L illustrate stent deployment methodology to be carried out with the subject delive guide member; alternative stent deployment acts are shown in Figs. 4D'-4F.
• Figs. 5 A and 5B show distal sectional views of delivery systems according to the present invention, together with detail views as indicated;
• Fig. 6 shows a handle as may be used in the present invention
• Fig. 7 shows the handle of Fig. 6 in cross-section, together with detail views as indicated;
• Fig. 8 shows another exemplary variation of a subject delivery system having a corewire provided with an embolic filter.
• FIG. 1 shows a heart 2 in which its vessels may be the subject of one or more angioplasty and/or stenting procedures.
• significant difficulty or impossibility is confronted in reaching smaller coronary arteries 4.
• a stent and a delivery system could be provided for accessing such small vessels and other difficult anatomy, an additional 20 to 25% of coronary percutaneous procedures could be performed with such a system.
• Such potential offers opportunity for huge gains in human healthcare and a concomitant market opportunity in the realm of roughly $1 billion U.S. dollars - with the further benefit of avoiding loss of income and productivity of those treated.
• small coronary vessels it is meant vessels having an inside diameter between about 1.5 or 2 and about 3 mm in diameter. These vessels include, but are not limited to, the Posterior Descending Artery (PDA), Obtuse Marginal (OM) and small diagonals. Conditions such as diffuse stenosis and diabetes produce conditions that represent other access and delivery challenges which can be addressed with a delivery system according to the present invention.
• Other extended treatment areas addressable with the subject systems include vessel bifurcations, chronic total occlusions (CTOs), and prevention procedures (such as in stenting of vulnerable plaque).
• DES drug eluting stent
• self-expanding stents may offer one or more of the following advantages over balloon-expandable models: 1) greater accessibility to distal, tortuous and small vessel anatomy - by virtue of decreasing crossing diameter and increasing compliance relative to a system requiring a deployment balloon, 2) sequentially controlled or "gentle” device deployment, 3) use with low pressure balloon pre-dilatation (if desirable) to reduce barotraumas, 4) strut thickness reduction in some cases reducing the amount of "foreign body” material in a vessel or other body conduit, 5) opportunity to treat neurovasculature - due to smaller crossing diameters and/or gentle delivery options, 6) the ability to easily scale-up a successful treatment system to treat larger vessels or vice versa, 7) a decrease in system complexity, offering potential advantages both in terms of reliability and system cost, 8) reducing intimal hyperplasia, and 9) conforming to tapering anatomy - without imparting complimentary geometry to the stent (though this option exists as well).
• Fig. 2A The stent pattern pictured is well suited for use in small vessels. It may be collapsed to an outer diameter of about 0.018 inch (0.46 mm), or even smaller to about 0.014 inch (0.36 mm) - including the restraint/joint used to hold it down - and expand to a size (fully unrestrained) between about 1.5 mm (0.059 inch) or 2 mm (0.079 inch) or 3 mm (0.12 inch) and about 3.5 mm (0.14 inch).
• the stent In use, the stent will be sized so that it is not fully expanded when fully deployed against the wall of a vessel in order to provide a measure of radial force thereto (i.e., the stent will be "oversized" as discussed above). The force will secure the stent and offer potential benefits in reducing intimal hyperplasia and vessel collapse or even pinning dissected tissue in apposition.
• Stent 10 preferably comprises NiTi that is superelastic at or below room temperature and above (i.e., as in having an A f as low as 15 degrees C or even 0 degrees C). Also, the stent is preferably electropolished. The stent may be a DES unit. The drug can be directly applied to the stent surface(s), or introduced into pockets or an appropriate matrix set over at least an outer portion of the stent. The stent may be coated with gold and/or platinum to provide improved radiopacity for viewing under medical imaging.
• the thickness of the NiTi is about 0.0025 inch (0.64 mm).
• Such a stent is designed for use in a 3 mm vessel or other body conduit, thereby providing the desired radial force in the manner noted above. Further information regarding radial force parameters in coronary stents may be noted in the article, "Radial Force of Coronary Stents: A Comparative Analysis,” Catheterization and Cardiovascular Interventions 46: 380-391 (1999), incorporated by reference herein in its entirety. [0051] In one manner of production, the stent in Fig.
• 2A is laser or EDM cut from round NiTi tubing, with the flattened-out pattern shown wrapping around the tube as indicated by dashed lines.
• the stent is preferably cut in its fully-expanded shape.
• necked down bridge sections 12 are provided between axially/horizontally adjacent struts or arms/legs 14, wherein the struts define a lattice of closed cells 16. Terminal ends 18 of the cells are preferably rounded-off so as to be atraumatic.
• the bridge sections can be strategically separated or opened as indicated by the broken lines in Fig. 2A.
• the bridge sections are sufficiently long so that fully rounded ends 18 may be formed internally to the lattice just as shown on the outside of the stent if the connection(s) is/are severed to separate adjacent cells 16.
• junction sections 28 connect circumferentially or vertically adjacent struts (as illustrated). Where no bridge sections are provided, the junction sections can be unified between horizontally adjacent stent struts as indicated in region 30.
• each strut bridge 12 reduces material width (relative to what would otherwise be presented by a parallel side profile) to improve flexibility and thus trackability and conformability of the stent within the subject anatomy while still maintaining the option for separating/breaking the cells apart.
• stent 10 is employed in the cell end regions 18 of the design. Specifically, strut ends 20 increase in width relative to medial strut portions 22. Such a configuration distributes bending (during collapse of the stent) preferentially toward the mid region of the struts. For a given stent diameter and deflection, longer struts allow for lower stresses within the stent (and, hence, a possibility of higher compression ratios). Shorter struts allow for greater radial force (and concomitant resistance to a radially applied load) upon deployment.
• radiused or curved sections 26 provide a transition from a medial strut angle ⁇ (ranging from about 85 degrees to about 60 degrees) to an end strut angle ⁇ (ranging from about 30 to about 0 degrees) at the strut junctions 28 and/or extensions therefrom.
• gap 24 and angle ⁇ may actually be configured to completely close prior to fully collapsing angle ⁇ .
• the stent shown is not so-configured. Still, the value of doing so would be to limit the strains (and hence, stresses) at the strut ends 22 and cell end regions 18 by providing a physical stop to prevent further strain.
• angle ⁇ is set at 0 degrees.
• the gap 24 defined thereby by virtue of the noticeably thicker end sections 20 at the junction result in very little flexure along those lever arms.
• the strut medial portions are especially intended to accommodate bending.
• a hinging effect at the corner or turn 32 of junction section 28 causing rotation of the struts largely about angle ⁇ may provide for compression mode in this stent.
• stent 40 includes necked down bridge sections 42 provided between adjacent struts or arms/legs 44, wherein the struts define a lattice of closed cells 46.
• terminal ends 48 of the cells are preferably rounded-off so as to be atraumatic.
• the bridge sections 42 of stent 40 can be separated for compliance purposes. In addition, they may be otherwise modified (e.g., as described above) or even eliminated. Also, in each design, the overall dimensions of the cells and indeed the number of cells provided to define axial length and/or diameter may be varied (as indicated by the vertical and horizontal section lines in Fig. 3A).
• strut ends 50 may offer some increase in width relative to medial strut portions 52.
• the angle ⁇ is relatively larger.
• angle ⁇ in the Fig. 3 A/3B design is meant to collapse and the strut ends are meant to bend in concert with the medial strut portions so as to essentially straighten-out upon collapsing the stent, generally forming tear-drop spaces between adjacent struts.
• This approach offers a stress-reducing radius of curvature at strut junctures as well as maximum stent compression.
• the "S" curves defined by the struts are produced in a stent cut to a final or near final size (as shown in Figs. 3 A and 3B).
• the curves are preferably determined by virtue of their origination in a physical or computer model that is expanded from a desired compressed shape to the final expanded shape. So derived, the stent can be compressed or collapsed under force to provide an outer surface profile that is as solid or smooth and/or cylindrical as possible or feasible.
• Such action is enabled by distribution of the stresses associated with compression to generate stains to produce the intended compressed and expanded shapes. This effect is accomplished in a design unaffected by one or more expansion and heat setting cycles that otherwise deteriorate the quality of the superelastic NiTi stent material. Further details regarding the "S" stent design and alternative stent constructions as may be used in the present invention are disclosed in U.S. Provisional Patent Application Serial No. 60/619,437, entitled, "Small Vessel Stent Designs", filed October 14, 2004 and incorporated herein by reference in its entirety.
• very high compression ratios of the stent may be achieved from about 5X to about 1OX or above.
• Delivery systems according to the present invention are advantageously sized to correspond to existing guidewire sizes.
• the system may have about an 0.014 (0. 36mm), 0.018 (0.46mm), 0.022 (0.56mm), 0.025 (0.64mm) inch crossing profile.
• intermediate sizes may be employed as well, especially for full-custom systems.
• the system sizing may be set to correspond to French (FR) sizing. In that case, system sizes contemplated range at least from about 1 to about 2 FR, whereas the smallest known balloon-expandable stent delivery systems are in the size range of about 3 to about 4 FR.
• the overall device crossing profile matches a known guidewire size, they may be used with off-the-shelf components such as balloon and microcatheters.
• the corewire member of the device is likewise advantageously so-sized for similar reasons as elaborated upon herein and other.
• the system enables a substantially new mode of stent deployment in which delivery is achieved through an angioplasty balloon catheter or small microcatheter lumen. Further discussion and details of "through the lumen" delivery is presented in U.S. Patent Application Serial No. 10/746,455 "Balloon Catheter Lumen Based Stent Delivery Systems” filed on December 24, 2003 and its PCT counterpart US2004/008909 filed on March 23, 2004, each incorporated by reference in its entirety. [0067] In larger sizes, (i.e., up to about 0.035 inch crossing profile or more), the system is most applicable to peripheral vessel applications as elaborated upon below.
• a stent delivery system sized at between about 0.022 to about 0.025 inch in diameter.
• Such a system can be used with catheters compatible with 0.022 and/or 0.025 inch diameter guidewires.
• stents in larger, peripheral vessels, biliary ducts or other hollow body organs.
• Such applications involve a stent being emplaced in a region having a diameter from about 3.5 to about 13 mm (0.5 inch).
• a 0.035 to 0.039 inch (3 FR) diameter crossing profile system is advantageously provided in which the stent expands (unconstrained) to a size between about roughly 0.5 mm and about 1.0 mm greater than the vessel or hollow body organ to be treated.
• Sufficient stent expansion is easily achieved with the exemplary stent patterns shown in Figs. 2A/2B or 3A/3B.
• the smallest delivery systems known to applicants for stent delivery in treating such larger-diameter vessels or biliary ducts is a 6 FR system (nominal 0.084 inch outer diameter), which is suited for use in an 8 FR guiding catheter.
• the present invention affords opportunities not heretofore possible in achieving delivery systems in the size range of a commonly used guidewire, with the concomitant advantages discussed herein.
• FIGs. 4A-4L illustrate an exemplary angioplasty procedure. Still, the delivery systems and stents or implants described herein may be used otherwise - especially as specifically referenced herein.
• Fig. 4A it shows a coronary artery 60 that is partially or totally occluded by plaque at a treatment site/lesion 62.
• a guidewire 70 is passed distal to the treatment site.
• a balloon catheter 72 with a balloon tip 74 is passed over the guidewire, aligning the balloon portion with the lesion (the balloon catheter shaft proximal to the balloon is shown in cross section with guidewire 70 therein).
• balloon 74 is expanded (dilatated or dialated) in performing an angioplasty procedure, opening the vessel in the region of lesion 62.
• the balloon expansion may be regarded as "predilatation” in the sense that it will be followed by stent placement (and optionally) a "postdilataton” balloon expansion procedure.
• the balloon is at least partially deflated and passed forward, beyond the dilate segment 62' as shown in Fig. 4D.
• guidewire 70 is removed as illustrated in Fig. 4E. It is exchanged for a delivery guide member 80 carrying stent 82 as further described below. This exchange is illustrated in Figs. 4E and 4F.
• the original guidewire device inside the balloon catheter may be that of item 80, instead of the standard guidewire 70 shown in Fig. 4A.
• the steps depicted in Figs. 4E and 4F may be omitted.
• Fig. 4G illustrates the next act in either case.
• the balloon catheter is withdrawn so that its distal end 76 clears the lesion.
• delivery guide 80 is held stationary, in a stable position. After the balloon is pulled back, so is delivery device 80, positioning stent 82 where desired. Note, however, that simultaneous retraction may be undertaken, combining the acts depicted in Figs. 4G and 4H. Whatever the case, it should also be appreciated that the coordinated movement will typically be achieved by virtue of skilled manipulation by a doctor viewing one or more radiopaque features associated with the stent or delivery system under medical imaging.
• stent deployment commences.
• the manner of deployment is elaborated upon below.
• stent 82 assumes an at least partially expanded shape in apposition to the compressed plaque as shown in Fig. 41.
• the aforementioned postdilatation may be effected as shown in Fig. 4J by positioning balloon 74 within stent 82 and expanding both. This procedure may further expand the stent, pushing it into adjacent plaque - helping to secure each.
• Fig. 4L shows a detailed view of the emplaced stent and the desired resultant product in the form of a supported, open vessel.
• delivery system 80 is too large to pass through the lumen of a balloon catheter.
• the procedure follows another path. Specifically, instead of advancing the balloon catheter after dilatation as in Fig. 4D, it is instead withdrawn as shown in Fig. 4D' lumen, the balloon catheter is withdrawn.
• a standard catheter/microcatheter 84 is advanced over original guidewire 70.
• the guidewire is exchanged for the delivery system 80'. With the delivery system in place and delivery catheter 82 withdrawn proximal of the lesion, the stent is deployed as shown in Fig. 4G'.
• the delivery system may then be stripped down to its corewire 86 as elaborated upon below.
• a delivery system as described illustrated in connection with Fig. 5A below it is possible to exchange the microcatheter for a balloon catheter to effect post dilatation as shown in Fig. 4H'.
• the balloon catheter 74 overrides the stent carrying region delivery device.
• a delivery device 80' is employed as described in connection with Fig. 5B, as shown in Fig. 4F the corewire 86 is advanced to a position so that stop feature 88 provided to block proximal motion of the stent upon sheath retraction will not interfere with advancing the balloon catheter to effect post post-dilatation.
• the corewire may be used for other subsequent procedures such as navigation to another target location for stenting, etc.
• the element functions as or substantially like a typical guidewire.
• the subject invention may be practiced to perform "direct stenting.” That is, a stent may be delivered alone to maintain a body conduit, without preceding balloon angioplasty. Likewise, once one or more stents are delivered with the subject system (either by a single system, or by using multiple systems) the post-dilatation procedure(s) discussed above are merely optional. In addition, other endpoints may be desired such as implanting an anchoring stent in a hollow tubular body organ, closing off an aneurysm, delivering a plurality of stents, etc. In performing any of a variety of these or other procedures, suitable modification will be made in the subject methodology. The procedure shown is depicted merely because it illustrates a preferred mode of practicing the subject invention, despite its potential for broader applicability.
• FIGS. 5B show views of a distal end of two exemplary delivery systems according to the present invention.
• a proximal end of the delivery system may employ a handle as describe in connection with Figs. 6A and 6B, discussed further below.
• the elongate or shaft portion of the device may have a length 150 to 180 cm. Alternatively, it may be about 300 cm long to facilitate exchange of over the wire catheters without a "dock" extension.
• FIG. 5A shows a distal end or shaft 100 of the subject delivery system 80.
• the device preferably comprises a flexible atraumatic distal tip 102 of one variety or another.
• the tip is typically mounted to a tapered section of corewire 104.
• Corewire 104 may have a number of tapered sections transitioning between different diameter sections as shown.
• a more proximal section "P" is larger in diameter than a more distal section “D” of the wire.
• Such an approach offers good distal flexibility, but in a robust enough wire with good pushability (column strength) and torque transmission characteristics.
• the distal reduced diameter section of the wire upon which stent 82 is mounted will typically have a length of at least about 5 to 15 cm proximal of blocker 88.
• the length of this region is important because it defines the portion of the device with the most space between corewire 104 and outer sleeve 106. Inner sleeve 108 occupies some of this space.
• a distal end 110 of the sleeve serves an additional purpose as well - as elaborated upon below.
• the sleeve occupying space up to a point adjacent to the stent (e.g., directly adjacent the stent or about a blocker's width away), it functions to control stent deployment during delivery.
• the parts By providing a system with minimal internal gaps, when in tortuous anatomy and pulling/pushing members relative to one another to remove a tubular member to release a stent, the parts remain substantially coaxially aligned. With larger gaps, misalignment occurs in which components in tension are pulled into a minimum radius configuration and components in compression are pushed into a maximum radius configuration.
• a two-sleeve solution addresses each of these problems in a number of ways.
• Straight- gauge tubing can be employed to provide an advantageous combined profile. Such an approach may offer higher precision in construction as well as reduced cost.
• the use of two sleeves with small gaps between them has proven advantageous for flushing the system in preparation for use. Such action may be assisted by providing - in essence - multiple capillary channels to "wick-in" fluid. Flushing (and hence filling) at least the distal end of the system with saline prior to insertion in the body avoids capillary action pulling blood into the system to hamper actuation.
• Hydrophilic coatings may be employed to assist in this matter as well.
• the system in Fig. 5 A uses a distal end 112 of inner sleeve 108 in coordinated use with a raised feature 88 on the guidewire as a combination stent stop, blocker or abutment interface.
• the raised feature comprises a solid body bonded, welded, soldered or otherwise attached to the corewire or a feature ground into the wire.
• Combined blocker 114 is formed with the distal end of the sleeve in place. It abuts stent 82 when sleeve 106 is withdrawn to release the stent. Then, when inner sleeve 108 is removed form "bump" 88, a relatively small feature remains.
• bump 88 serves a critical function by occupying space to the stent does not slip inwardly and pass inner sleeve upon outer sleeve withdrawal.
• sleeve 108 is typically less than about 0.002 inch thick. More often, it is between about 0.0015 and about 0.001 inch thick. Relative to the stent, sleeve 108 may be between about 1/4 to about 3/4 the thickness of the stent.
• Feature 88 and inner sleeve distal end 112 may remain aligned by virtue of the length of sleeve 108.
• a light press interference fit, adhesive, etc may be employed to temporarily lock the members together until release is intended.
• the length of element 88 may be between about 1 and about 5 mm. Too short a section and sleeve 108 may be prone to slip past the feature; too long a section and it may deleteriously affect flex performance of the core member.
• an advantage of the combined sleeve/core feature blocker 114 is that it offers a relatively smaller diameter "bump" remainder on the corewire after sleeve removal. This fact, in turn, facilitates the methodology referenced in Fig. 4H' in which after stent delivery by releasing the stent from a distal portion of the outer sleeve, each of the inner and outer sleeves have been removed. With the device utilizing the combination blocker approach, the stent abutment feature then has a low enough profile that it does not interfere with subsequent use of the core member as a fully functional guidewire. In this manner, a balloon catheter or another member advanced over the core member after removal of the other system components. Especially where the abutment/blocker member diameter is larger than about 0.002 inch over an adjacent section (0.004 inch greater than diameter), ramp section(s) 116 on the proximal side of feature 88 may be provided to offer an improved transition.
• raised feature 88/88' may comprise a gold or platinum band connected to the corewire in order to serve a marker function.
• a distal marker band may also be provided in the system.
• Such a band (not shown) may be attached to a distal end of the sleeve 106.
• proximal or distal section(s) 120 of tip 102 may comprise highly radiopaque platinum material.
• the various radiopaque markers or features may be employed in the system to 1) locate stent position and length or that of other devices/features (e.g., an embolic filter), 2) indicate device actuation and stent delivery and/or 3) locate the distal end of the delivery guide.
• the overhang feature serving (at least in part) stent stop or blocker member may be made of radiopaque material. Especially where the stent employed may shorten somewhat upon deployment, it may also be desirable to align radiopaque features with the expected location (relative to the body of the delivery guide member) of the stent upon deployment.
• each of the inner and outer tubular members are preferably splitable.
• the inner sleeve 108 may be pre-split so long as the outer sleeve 106 is unsplit over at least a portion of its length so as to support the inner member.
• the tubular members may be coated with a hydrophilic coating for lubricity.
• Materials may be selected for use in constructing the guidewire core and tubular members as commonly in other stent delivery and in other catheter systems. Exemplary materials include Nylon, LLDPE, HDPE, PET, PEEK and PTFE.
• a handle 130 is advantageously provided as shown in Fig. 6.
• a cross-sectional view of the handle, together with highlighted details is shown in Fig. 7.
• the handle includes a body 132 defining a slot 134 through which a slide 136 can be pulled.
• the slide may includes a sleeve lumen 138 branching off of a central lumen 140 of the device through which delivery device shaft 100/100' is received.
• outer sleeve 106 separates from the inner sleeve and corewire, and is received within lumen 138.
• Sleeve 106 is then bent over and received within channel 142 and secured to the slider via thumbscrew 144. So-configured, sleeve 106 travels with slider 136 when withdrawn through slot 134.
• a thumbscrew is released and sleeve 106 may be withdrawn from the assembly by grasping optional end grip and pulling.
• a blade (not shown) may be incorporated to split the sleeve prior to its divergence from inner sleeve 106 and corewire 104.
• Slider 136 may also receive a section of hypotube 150 received within a second piece of hypotube received by handle end plug 160.
• the hypotube pair 150/152 receives sleeve 106 and wire 104 providing these members under compressive force during stent deployment with support as well as protection.
• plug 160 it too may include a sleeve lumen 162. In which case, inner sleeve
• both of the inner sleeve 108 and corewire 104 may exit the handle in a co-axial arrangement.
• sleeve 106 is stripped from corewire 104 after screw 164 is released.
• handle 130 may be removed from the sleeve and/or corewire.
• handle 130 may include strain relief tubing 170. These may comprise one or more tubes to ease the transition from an end cap 172 of the handle.
• System 180 includes a stent 82 and stop feature 88' arrangement similar to that of delivery system 100' of Fig. 5B. Naturally, the arrangement may alternatively be practiced with a stop feature arrangement as shown in Fig. 5 A.
• the system includes an optional filter component 182 on distal section
• the system may function as a combination embolic filter and stent delivery system. Stated otherwise, a stent delivery system with embolic protection capability is provided.
• filter component 182 comprises an expansion frame having a plurality of outwardly biased struts 184 extending between a mesh filter 186 at a distal end and a frame base 188 coupled to corewire 104.
• Filter component 182 may have any suitable construct, many of which are known in the art, such as those disclosed in U.S. Patent No. 6,027,520, incorporated herein by reference in its entirety.
• filter component 182 may be self-expanding (as illustrated) and retained in a constrained condition by outer sheath 106 in a manner similar to the manner by which self-expanding stent 82 is constrained prior to deployment.
• filter 182 may have an active configuration driven by shape memory alloy effect.
• the distance between the stent and filter may vary. For a distal coronary application, however, the distance is typically between about 0.5 mm and about 5.0 mm.
• deployment system 180 In the context of the angioplasty and stent deployment procedure described with respect to Figs. 4E-4J (and Figs. 4D'-4F), the use of deployment system 180 is described as follows. With as the system serving in the capacity of delivery guide 80 in Figs. 4E-4J, distal tip 102 and filter 182 are advanced distal of the lesion 62 and beyond the distal end of outer sheath 106. Either by self-expansion, passive expansion (i.e., by blood flow within the artery) or active expansion, filter 186 is expanded (not illustrated) to operatively filter any emboli that may be released in the course of the predilatation procedure while allowing the filter blood to pass distally.
• passive expansion i.e., by blood flow within the artery
• active expansion filter 186 is expanded (not illustrated) to operatively filter any emboli that may be released in the course of the predilatation procedure while allowing the filter blood to pass distally.
• the filter then, remains deployed throughout the stent deployment and/or postdilatation procedures to capture any dislodged particulates.
• Stent 82 is deployed from deployment system 180 in the same manner as described above.
• the filter is retrieved, typically by advancing sheath 106 or the guide or balloon catheter used over the proximal portion of the device to once-again compress its shape.
• the methods may all comprise the act of providing a suitable device. Such provision may be performed by the end user.
• "providing” e.g., a delivery system
• providing merely requires the end user to obtain, access, approach, position, set-up, activate, power-up or otherwise act to provide the requisite device in the subject method.
• Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as in the recited order of events.
• any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein.
• Reference to a singular item includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms "a,” “an,” “said,” and “the” include plural referents unless the specifically stated otherwise. In other words, use of the articles allow for "at least one" of the subject item in the description above as well as the claims below. It is further noted that the claims may be drafted to exclude any optional element.

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  • 2006-05-22 US US11/439,378 patent/US20070027522A1/en not_active Abandoned
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