US20120004717A1 - Apparatus and methods for delivering a stent into an ostium - Google Patents

Abstract

Apparatus and methods are provided for delivering a stent into an ostium. The apparatus includes a catheter including a proximal end, a distal end, and proximal and distal balloons disposed adjacent one another on the distal end. The balloons are expandable independently of one another, and a stent is provided surrounding the balloons. During use, the distal end of the catheter is introduced into a main lumen, and the proximal balloon is inflated to flare a proximal portion of the stent. The distal end is then advanced into the ostium until the flared proximal portion contacts a wall of the main lumen surrounding the ostium. The distal balloon is inflated to expand a distal portion of the stent, e.g., to dilate a lesion within the branch and/or ostium. Thereafter, the balloons are collapsed, and the apparatus is withdrawn, leaving the stent within the ostium.

Description

RELATED APPLICATION DATA
• This application is a continuation of application Ser. No. 11/136,266, filed May 23, 2005, issuing as U.S. Pat. No. 7,862,601, the entire disclosure of which is expressly incorporated by reference herein.
FIELD OF THE INVENTION
• The present invention relates generally to apparatus and methods for delivering an endoluminal prosthesis, e.g., a stent, into a body lumen and, more particularly, to apparatus and methods for delivering a stein into an ostium of a blood vessel or other body lumen.
BACKGROUND
• Tubular endoprosthesis or “stents” have been suggested for dilating or otherwise treating stenoses, occlusions, and/or other lesions within a patient's vasculature or other body lumens. For example, a self-expanding stent may be maintained on a catheter in a contracted condition, e.g., by an overlying sheath or other constraint, and delivered into a target location, e.g., a stenosis within a blood vessel or other body lumen. When the stent is positioned at the target location, the constraint may be removed, whereupon the stent may automatically expand to dilate or otherwise line the vessel at the target location. Alternatively, a balloon-expandable stent may be carried on a catheter, e.g., crimped or otherwise secured over a balloon, in a contracted condition. When the stent is positioned at the target location, the balloon may be inflated to expand the stent and dilate the vessel.
• Sometimes, a stenosis or other lesion may occur at an ostium or bifurcation, i.e., where a branch vessel extends from a main vessel. For example, such a lesion may form within a coronary artery immediately adjacent the aortic root. U.S. Pat. No. 5,749,890 to Shaknovich discloses a stent delivery assembly for placing a stent in an ostial lesion. U.S. Pat. No. 5,632,762 to Myler discloses a tapered balloon on a catheter for positioning a stent within an ostium, U.S. Pat. No. 5,607,444 to Lam discloses an expandable ostial stent including a tubular body and a deformable flaring portion. Published application US 2002/0077691 to Nachtigall discloses a delivery system that includes a sheath for holding a stent in a compressed state during delivery and a retainer that holds a deployable stop in an undeployed position while the delivery system is advanced to a desired location.
• Accordingly, apparatus and methods for delivering a stent within an ostium would be useful.
SUMMARY OF THE INVENTION
• The present invention is directed to apparatus and methods for delivering stents or other endoluminal prostheses, and, more particularly, to apparatus and methods for delivering a stent into an ostium or bifurcation of a blood vessel or other body lumen, e.g., for dilating or otherwise lining and/or treating an occlusion or other lesion at the ostium.
• In accordance with one embodiment, apparatus is provided for delivering a prosthesis into an ostium of a body lumen. The apparatus may include an elongate tubular member including a proximal end, and a distal end sized for introduction into a body lumen. A first expandable member may be provided on the distal end of the elongate member, and a second expandable member may be provided on the distal end of the elongate member adjacent the first expandable member, the second expandable member being expandable independently of the first expandable member. The apparatus may include a prosthesis including a first portion surrounding or otherwise adjacent the first expandable member and a second portion surrounding or otherwise adjacent the second expandable member. The second expandable member may be expandable for expanding the second portion to an enlarged condition white the first expandable member and the first portion remain in a contracted condition. The first expandable member may be expanded for expanding the first portion to an enlarged condition that is smaller than the second portion in its enlarged condition.
• Optionally, the apparatus may include a constraint, e.g., overlying sheath for covering at least the first portion, for maintaining the first portion in the contracted condition while the second expandable member is expanded. The constrain may be movable for covering and uncovering the first portion. Optionally, the constraint may also be movable for covering and uncovering the second portion, e.g., independently of the first position.
• In one embodiment, the second expandable member may include a transverse surface when expanded that is disposed adjacent the first expandable member, e.g., for deforming the second portion of the prosthesis transversely as the second expandable member is expanded.
• In accordance with another embodiment, an apparatus is provided for delivering a prosthesis into an ostium of a body lumen that includes an elongate member including a proximal end, a distal end sized for introduction into a body lumen, a first expandable member on the distal end of the elongate member including a length for receiving a first portion of a tubular prosthesis thereon, and a second expandable member on the distal end of the elongate member adjacent the first expandable member for receiving a second portion of the tubular prosthesis thereon. A portion of the second expandable member may be attached to the first expandable member, while the second expandable member may be expandable independently of the first expandable member for expanding the second portion to an enlarged condition while the first portion remains in a contracted condition.
• In addition, the apparatus may include a stent or other prosthesis including a first portion surrounding the first expandable member and a second portion surrounding the second expandable member. In one embodiment, in an enlarged condition, the second expandable member may define a transverse surface adjacent the first expandable member for expanding the second portion of the prosthesis to a flared condition to facilitate placement of the prosthesis within an ostium.
• In accordance with another embodiment, a method is provided for implanting a prosthesis within an ostium or bifurcation extending from a main lumen into a branch lumen, e.g., using an elongate member including first and second expandable members on a distal end of the elongate member. Initially, the distal end of the elongate member may be advanced into the main lumen with first and second portions of the prosthesis adjacent the first and second expandable members, respectively. The second expandable member may be expanded to cause the second portion of the prosthesis to expand transversely, and the distal end may be advanced into the ostium until the expanded second portion contacts a wall of the main lumen surrounding the ostium and the first portion of the prosthesis is disposed within the branch lumen. The first expandable member may be expanded to expand the first portion of the prosthesis to contact a wall of the branch lumen.
• Thereafter, the first and second expandable members may be collapsed, and the elongate member may be withdrawn from the branch and main lumens, leaving the prosthesis with the first portion expanded within the branch lumen and the second portion contacting the wall of the main lumen surrounding the ostium.
• In one embodiment, the first portion may be constrained while the second expandable member is expanded, and the constraint may be removed before expanding the first expandable member. In addition, the second portion may be at least partially deformed as the distal end of the elongate member is advanced into the ostium such that the second portion conforms at least partially to a shape of the of the main lumen surrounding the ostium.
• In another embodiment, the prosthesis may be provided on the elongate member with the first and/or second portions relaxed in a contracted condition for delivery. As the first and/or second expandable members are expanded, the first and/or second portions may be plastically deformed outwardly, e.g., to dilate or otherwise line the lesion. In still another embodiment, the first and/or second portions of the prosthesis may be biased to expand from a contracted condition for delivery on the elongate member towards an enlarged condition. For example, a constraint may be provided that maintains the first and/or second portions of the prosthesis in the contracted condition. When the constraint is removed, the first and/or second portions may automatically expand towards the enlarged condition. Thereafter, the first and/or second expandable members may be expanded to expand the first and/or second portions further, e.g., to plastically deform or otherwise engage the prosthesis with the ostium, e.g., to dilate an occlusion or other lesion at or adjacent the ostium.
• Other aspects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The drawings illustrate exemplary embodiments of the invention, in which:
• FIG. 1 is a perspective view of an exemplary embodiment of a balloon apparatus for delivering a stent into an ostium.
• FIG. 2 is a cross-sectional side view of a distal end of the apparatus ofFIG. 1,
• FIG. 3 is a partial cross-sectional side view of another embodiment of a balloon apparatus for delivering a stent into an ostium.
• FIGS. 4A-4C are side views of a distal end of yet another embodiment of a balloon apparatus for delivering a stent into an ostium.
• FIGS. 5A-5F are cross-sectional views of a patient's body, showing a method for implanting a stent within an ostium where a branch vessel extends from a main vessel.
• FIGS. 6A-6C are side views of a distal end of still another embodiment of a balloon apparatus including a movable sheath for covering and uncovering a stent carried on the apparatus.
• FIGS. 7 and 8 are cross-sectional side of a distal end of alternative embodiments of a ballot apparatus for delivering a stent into an ostium.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Turning to the drawings,FIGS. 1 and 2 show an exemplary embodiment of aballoon apparatus10 for delivering a stent orother prosthesis40, e.g., into an ostium or other bifurcation between a main lumen and a branch lumen (not shown). Generally, theapparatus10 includes a catheter or other elongatetubular member12 having aproximal end14, adistal end16, and one or more lumens18 extending between the proximal and distal ends14,16, thereby defining alongitudinal axis20 between the proximal and distal ends14,16. One or more balloons or other expandable members22 are provided on thedistal end16, e.g., a firstdistal balloon22aand a secondproximal balloon22bas shown. Optionally, one or more additional expandable members (not shown) may be provided on thedistal end16 adjacent the first and/orsecond balloons22a,22b.
• Thecatheter12 may be formed from one or more tubular bodies, e.g., having variable flexibility along its length. For example, thedistal end16 may be substantially flexible to facilitate insertion through tortuous anatomy, e.g., terminating in a rounded or other substantiallyatraumatic tip17. Thedistal end16 may be sized and/or shaped for introduction into a body lumen, e.g., having a diameter between about one and seven millimeters (1-7 mm), or less than 1.5 mm. Theproximal end14 may be substantially flexible or semi-rigid, e.g., having sufficient column strength to facilitate advancing thedistal end16 through a patient's vasculature by pushing on theproximal end14. Thecatheter12 may be formed from plastic, metal, or composite materials, e.g., a plastic material having a wire, braid, or coil core, which may preventing kinking or buckling of thecatheter12 during advancement.
• As shown inFIG. 1, thecatheter12 may include ahandle30 on theproximal end14, e.g., to facilitate manipulating theapparatus10. Thehandle30 may include one or more side ports32 communicating with respective lumens18 within thecatheter12. Thehandle30 may be molded, machined, or otherwise formed from plastic, metal, or composite material, e.g., providing an outer casing, which may be contoured or otherwise shaped to ease manipulation. Theproximal end14 of thecatheter12 may be attached to thehandle30, e.g., by bonding, cooperating connectors, interference fit, and the like. Optionally, if the apparatus includes any actuatable components (not shown, see, e.g.,FIGS. 6A-6C) on thedistal end16, thehandle30 may include one or more actuators (not shown), such as one or more slides, dials, buttons, and the like, for actuating or otherwise manipulating the components on thedistal end16 from theproximal end14, as explained further below.
• As best seen inFIG. 2, thecatheter12 includes at least three lumens18 extending between the proximal and distal ends14,16. For example, thecatheter12 may include aninstrument lumen18athat extends from aport32ain thehandle30 to anopening34ain thedistal tip17. The instrument lumen18amay have sufficient size to allow a guidewire or other rail or instrument (not shown) to be inserted therethrough, e.g., to facilitate advancing thecatheter12 over the rail, as explained further below. Optionally, thehandle30 may include one or more seals (not shown) adjacent theport32a, e.g., a hemostatic seal that prevents fluid, e.g., blood, from flowing proximally out of theport32a, yet allows one or more instruments to be inserted therethrough and into theinstrument lumen18a.
• In addition, thecatheter12 may includeinflation lumens18b,18cthat extend fromrespective side ports32b,32cin thehandle30 through thecatheter12 toopenings34b,34con thedistal end16. Eachopening34b,34ccommunicates within an interior23a,23bof arespective balloon22a,22b. Theside ports32b,32con thehandle30 may include connectors, e.g., a luer lock connector (not shown), one or more seals (also not shown), and the like. A source of inflation media and/or vacuum, e.g., a syringe filled with saline (not shown), may be connected to theside ports32h,32c, e.g., via tubing (also not shown), for expanding and/or collapsing the balloons22. As shown inFIG. 2, the lumens18 are disposed adjacent one another. Alternatively, the lumens18 may be disposed in concentric or other arrangements within the body of thecatheter12. In addition, if theapparatus10 includes additional balloons (not shown) on thedistal end16, thecatheter12 may include one or more additional inflation lumens (also not shown), and thehandle30 may include one or more additional ports (also not shown), similar to those shown and described with reference toFIG. 2.
• Alternatively, other configurations of lumens may be provided for delivering fluid to and/or aspirating fluid from one or both balloons22. For example, a single lumen may be provided (not shown) that communicates with the interiors23 of both balloons22. This embodiment may allow the balloons22 to be expanded and/or collapsed substantially simultaneously using a single syringe or other source of fluid/vacuum. In another alternative, thecatheter12 may includeseparate inflation lumens18b,18c, but thehandle30 may include a single side port (not shown) to which a syringe or other source of fluid/vacuum may be connected. In this alternative, thehandle30 may include a switch, stopcock, valve, or other device for selectively connecting one or bothinflation lumens18b,18cto the side port. For example, a three-way valve may be directed to first or second positions to allow the side port to be connected to either of theinflation lumens18b,18c, e.g., for inflating/collapsing anindividual balloon22a,22b. In a third position, the side port may be connected to bothlumens18b,18cfor inflating/collapsing both balloons22 simultaneously. This configuration may be particularly useful for quickly collapsing both balloons22 after implanting thestent40 before removing theapparatus10. In addition, the configuration may facilitate expanding theentire stent40, e.g., after expanding and anchoring thefirst portion42 and/or after flaring thesecond portion44.
• Turning toFIG. 3, in an alternative embodiment theapparatus10′ may include acatheter12′ including a plurality of tubular members disposed adjacent one another. The tubular members of thecatheter12′ may be individual tubular bodies bonded or otherwise attached to one another along their lengths, a single body extruded or otherwise molded to include the tubular members as an integral unit, and the like. Otherwise, the materials and methods of thecatheter12′ may be similar to the other embodiments described herein. Each tubular member may include a single or multiple lumens18′ therein. Optionally, different sections of thecatheter12′ between theproximal end14′ and thedistal end16′ may have different cross-sections. For example, the different sections along the length of thecatheter12′ may be formed separately and attached to one another, e.g., by bonding, interference fit, melting or otherwise fusing the sections together, using an internal or external collar or sleeve (not shown), and the like. For example, as shown inFIG. 3, thedistal end14′ includes three lumens18,′ while theproximal end16′ may include only twolumens18b′-18c.′
• As shown inFIG. 3, thecatheter12′ may include aninstrument lumen18a′ that extends along thedistal end16′ of thecatheter12′ between aproximal opening32a′ and adistal opening34a′ in distal tip17.′ Theproximal opening32a′ may be located a predetermined distance from thedistal tip17,′ e.g., between about eighty to three hundred millimeters (80-300 mm), to provide a “rapid-exchange” apparatus that may facilitate quickly exchanging guidewires within the instrument lumen18a.′ Optionally, theproximal opening32a′ may include a ramped or tapered surface, e.g., to facilitate inserting and/or removing guidewires and the like into and out of the instrument lumen18a.′
• Returning toFIGS. 1 and 2 (although the materials and methods may be applicable to other embodiments described herein), the balloons22 may be bonded or otherwise secured to thedistal end16 of thecatheter12. For example, ends24,26 of the balloons22 may be attached to thedistal end16 by bonding with an adhesive, by sonic welding, using an annular collar or sleeve, and the like. Thedistal balloon22amay include aproximal end24aattached to thedistal end16 of thecatheter12 proximal to opening34cand adistal end26aattached adjacent thedistal tip17. Thedistal balloon22amay be expandable from a contracted condition (not shown), which may facilitate advancement within a patient's vasculature, to an enlarged condition, as shown inFIGS. 1 and 2.
• In the enlarged condition, thedistal balloon22amay include anintermediate portion28ahaving a substantially uniform cross-section, as best seen inFIG. 2. Alternatively, theintermediate portion28amay have other shapes if desired based upon anatomy encountered within a patient, e.g., a tapered shape that increases or decreases between the proximal and distal ends24a,26a. Theintermediate portion28amay have a length sufficient to receive at least a portion of astent40 thereon (as shown inFIG. 1), e.g., between about seven and thirty millimeters (7-30 mm). Thedistal balloon22amay be tapered, blunt, or otherwise transition from theintermediate portion28ato the proximal and distal ends24a,26a.
• Theproximal balloon22bmay include aproximal end24battached to thedistal end16 of thecatheter12 proximal to opening34band adistal end26battached to thedistal balloon22a, e.g., on or adjacent theintermediate portion28a. Thedistal end26bmay be bonded with an adhesive, sonic welded, or otherwise attached to thedistal balloon22ato provide a substantially fluid-tight seam or bond. Thus, the balloons22 may be expandable independent of one another, yet be inseparable from one another, e.g., to prevent any gaps or spaces from developing between the balloons22. In one embodiment, theproximal balloon22bmay have a length that is substantially shorter than thedistal balloon22a, e.g., between about five to fifty millimeters (5-15 mm). In addition or alternatively, at least a transversedistal surface28bof theproximal balloon22bmay have a length that is less than the length of theintermediate portion28aof thedistal balloon22a.
• In an alternative embodiment as shown inFIG. 3, theproximal balloon22b′ may extend at least partially over the distal balloon22a.′ For example, thedistal end26b′ of theproximal balloon22b′ may extend over the intermediate portion28.a′ of thedistal balloon22a′ and be attached over or adjacent to thedistal end26a′ of thedistal balloon22a,′ e.g., by bonding, sonic welding, and the like, as described elsewhere herein. This alternative may provide a seam that is substantially smaller, less bulky, more reliable, and/or easier to manufacture than the seam shown inFIG. 2.
• Turning toFIG. 7, in a further alternative, anapparatus210 is shown having acatheter212, including adistal end216, and a pair ofballoons222a,222bcarried on thedistal end216, similar to the other embodiments described herein. Similar components have been identified with similar reference numbers (although increased by 100 or 200). Unlike previous embodiments, adistal end226bof the proximal balloon222bmay be attached to thedistal end216 of thecatheter212 adjacent or directly to aproximal end224aof thedistal balloon222a. For example, as shown, thedistal end226bof the proximal balloon222bmay be bonded or otherwise attached over theproximal end224aof thedistal balloon222a. The proximal anddistal ends224a,226aof thedistal balloon222aand theproximal end224bof the proximal balloon222bmay be attached directly to thedistal end216 of thecatheter212, similar to the previous embodiments. Alternatively, theproximal end224aof thedistal balloon222amay be attached over thedistal end226bof the proximal balloon222b, which may be attached to thedistal end216 of the catheter212 (not shown). This embodiment may introduce a small gap between theintermediate region228aand thetransverse surface228bof the balloons222 when they are expanded, as shown inFIG. 7.
• Alternatively, as shown inFIG. 8, thedistal end326bof theproximal balloon322bmay be everted partially into the interior323bof theproximal balloon322b, e.g., to minimize any gap between the balloons322. For example, the proximal anddistal ends324a,326aof thedistal balloon322amay be attached to thedistal end316 of the catheter. Thedistal end326bof theproximal balloon322bmay be attached to theproximal end324aof thedistal balloon322asuch that the transverse surface328hof theproximal balloon322bis disposed immediately adjacent theintermediate region328aof thedistal balloon322a.
• Returning toFIG. 2, theproximal balloon22bmay be expandable from a contracted condition (not shown), which may facilitate advancement through a patient's vasculature to an enlarged condition. As shown, theproximal balloon22bmay be expandable independent of thedistal balloon22a. In the enlarged condition, theproximal balloon22bmay include a transversedistal surface28bthat extends transversely relative to the longitudinal axis18 and/orintermediate portion28awhen theproximal balloon22bis expanded. As shown inFIG. 2, thetransverse surface28bmay define a substantially obtuse angle with theintermediate portion28aof thedistal balloon22a, e.g., between about ninety and one hundred fifty degrees (90-150°).
• Alternatively, as shown inFIGS. 4B and 4C, thetransverse surface28b″ may define a substantially acute angle with theintermediate portion28a,″ e.g., between about sixty and ninety degrees (60-90°). In this alternative,transverse surface28b″ may define a concave shape or space into which thedistal balloon22a″ may at least partially nest as it expands, i.e., such that thedistal balloon22a″ expands against thetransverse surface28b,″ as shown inFIG. 4C.
• Returning toFIGS. 1 and 2, the balloons22 may be formed from substantially inelastic material, e.g., PET, nylon, or PEBAX, such that the balloons22 expand to a predetermined size in their enlarged conditions once sufficient fluid is introduced into the interiors23 of the balloons22. For example, thedistal balloon22amay be expandable to an enlarged condition in which theintermediate portion28ahas a diameter between about two to seven millimeters (2-7 mm), while theproximal balloon22bmay be expandable to a diameter between about four to twenty millimeters (4-20 mm). Thedistal balloon22amay be expandable to an enlarged condition that is smaller than theproximal balloon22b, e.g., such that thetransverse surface28bof theproximal balloon22bextends radially outwardly from theintermediate portion28aof thedistal balloon22awhen both balloons22 are expanded.
• Alternatively, one or both of the balloons22 may be formed from substantially elastic material, e.g., silicone, polyurethane, or polyethylene, such that the balloons22 may be expanded to a variety of sizes depending upon the volume and/or pressure of fluid within the interiors23. For example, in the embodiment shown inFIGS. 4A-4C, thedistal balloon22a″ may be substantially elastic, while theproximal balloon22b″ is substantially inelastic. As shown, astent40 may be disposed over the balloons22,″ e.g., such that afirst portion42 of thestein40 overlies thedistal balloon22a″ and asecond portion44 of thestent40 overlies theproximal balloon22b.″
• As shown, theproximal balloon22b″ may be expandable from a contracted condition (shown inFIG. 4A) to a predetermined size and shape in an enlarged condition (shown inFIGS. 4B and 4C). As theproximal balloon22b″ is expanded, thetransverse surface28b″ bears against thesecond portion44 of thestent40, causing thesecond portion44 to flare outwardly or otherwise deform, as shown inFIG. 4B. If theproximal balloon22b″ substantially inelastic, the resulting flare of thesecond portion44 may adopt a predetermined shape, e.g., a substantially straight or curved conical shape. The predetermined shape may be configured to correspond at least partially to a shape of an ostium within a patient's vasculature, as explained further below. Optionally, theproximal balloon22b″ may be at least somewhat compliant, e.g., such that, once fully inflated, theproximal balloon22b″ may be pressed against tissue surrounding the ostium with sufficient force to cause theproximal balloon22b″ to conform at least partially to the shape of the ostium. This action may cause thesecond portion44 of thestent40 to deform further, e.g., to conform to the shape of the ostium, which may enhance seating or securing thestent40 at a target location, as explained further below.
• Turning toFIG. 4C, thedistal balloon22a″ may be substantially elastic or otherwise more compliant than theproximal balloon22b.″ After expanding theproximal balloon22b″ to deform thesecond portion44 of the stent40 (as inFIG. 4B), thedistal balloon22a″ may be expanded, e.g., to cause thefirst portion42 of thestein40 to expand radially outwardly. As the internal pressure within thedistal balloon22a″ is increased (i.e., as additional fluid is delivered into thedistal balloon22a″), thedistal balloon22a″ may be expanded through a range of sizes, causing thefirst portion42 of thestent40 to expand radially outwardly.
• Because of its greater compliance and/or elasticity, thedistal balloon22a″ may be expanded until a desired size is attained, e.g., sufficient to dilate a branch body lumen communicating with the ostium or other target location, as explained further below. Fluoroscopy or other external imaging may be used as thedistal balloon22a″ is expanded, e.g., to monitor expansion of thefirst portion42 of thestent40, which may indicate the degree of dilation occurring within the target location. In addition, thedistal balloon22a″ may conform at least partially to the surrounding anatomy, e.g., distributing pressure more evenly along theintermediate portion28a″ such that thefirst portion42 of the stent conforms to the substantially uniform shape of theintermediate portion28a″ of thedistal balloon22a.″ Alternatively, thedistal balloon22a″ may be expandable to a predetermined size. This alternative may involve selecting anapparatus10″ having adistal balloon22a″ with an expanded size corresponding to the desired dilated size of the target location.
• With additional reference toFIGS. 4A-4C, theapparatus10″ (or any of the other embodiments described herein) may carry astent40, which may be formed from a variety of materials that may be plastically deformed to allow expansion of thestent40. For example, thestent40 may be formed from metal, such as stainless steel, tantalum, MP35N, Niobium, Nitinol, and L605, plastic, or composite materials. In particular, the materials of thestent40 may be plastically deformed under the pressures experienced when the balloons22″ are expanded, e.g., such that the first and/orsecond portions42,44 of thestent40 are deformed beyond their elastic limit. Thus, when the balloons22″ are subsequently collapsed, thestent40 may maintain its expanded configuration (e.g., that shown inFIG. 4C) with minimal recoil, e.g., thestent40 material may resist collapsing back towards its reduced configuration (e.g., that shown inFIG. 4A) if the tissue surrounding the body lumen attempts to constrict or otherwise return to its occluded shape.
• Alternatively, at least a portion of thestent40 may be self-expanding. For example, one or both of the first andsecond portions42,44 may be biased to expand at least partially outwardly yet may be constrained over the balloons22 in a contracted condition to facilitate delivery. In this alternative, thestent40 may be formed from Nitinol or other shape memory or superelastic materials.
• Optionally, the resistance of thestent40 to expansion may be varied along its length. This performance of thestent40 may be based upon mechanical properties of the material, e.g., which may involve heat treating one or more portions of thestein40 differently than other portions. In addition or alternatively, the structure of thestein40 may be varied, e.g., by providing struts, fibers, or other components in different portions having different widths, thicknesses, geometry, and the like. In one embodiment, the material of thefirst portion42 may require greater force to expand than thesecond portion44. Thus, thesecond portion44 may be more easily plastically deformed, which may allow theproximal balloon22b″ to be expanded using lower pressure than thedistal balloon22a.″
• Thestent40 may be a generally tubular structure, e.g., including openings in a tubular wall that facilitate expansion of thestent40 and/or allow tissue ingrowth. For example, the stent may be an elongate tube that has slots or other openings formed in the tube wall, e.g., by laser cutting, mechanical cutting, chemical etching, machining, and the like. Alternatively, thestent40 may be a braided or other structure, e.g., formed from one or wires or other filaments braided or otherwise wound in a desired manner. Additional possible stent structures may include helical coil wires or sheets. If desired, one or more portions of thestent40 may include a membrane, film, or coating (not shown), e.g., to create a nonporous, partially porous, or porous surface between cells of thestent40.
• For example, thesecond portion44 of thestent40 may include a substantially elastic membrane, e.g., PTFE, ePTFE, silicone, polyurethane, or polyethylene, that may be embedded into, coated onto, sandwiched around, or otherwise carried by thestent40. The membrane may be substantially elastic such that the membrane may expand when thesecond portion44 is flared or otherwise expanded. Alternatively, the membrane may be folded or otherwise compressed such that the membrane may unfold or otherwise to accommodate expansion as thestent40 is expanded. The membrane may be provided on an outer and/or inner surface of thesecond portion44. A membrane on the inner surface may facilitate recrossing thestent40 at a later time after implantation. For example, after thestent40 is implanted within a patient, it may be desirable to advance a guidewire or other instrument through the ostium into the branch vessel, e.g., to perform another procedure. This may occur during the same surgical procedure, or some time after the patient has recovered, e.g., when the branch vessel, lesion, or main vessel need subsequent treatment. The membrane may prevent the tip of a guidewire or other instrument from catching or tangling in the struts, cells, wires, or other structures of thestent40. Instead, the membrane may provide a substantially smooth, possibly lubricious surface that may guide a guidewire through thestent40 into the branch vessel.
• In addition or alternatively, a membrane on thestent40 may carry therapeutic or other compounds or materials. For example, a membrane on an outer surface of thestent40 may be pressed into contact with the plaque, damaged tissue, or other material of the lesion, allowing the compound to act to enhance healing or otherwise treat the lesion.
• Optionally, thestent40 may include one or more radiopaque or other markers (not shown), e.g., to facilitate monitoring thestent40 during advancement, positioning, and/or expansion. For example, a band of radiopaque material, e.g., gold, platinum, iridium, tungsten, or their alloys, may be provided on each end of thestent40 and/or adjacent the location where the first andsecond portions42,44 meet. In addition or alternatively, theapparatus10 may include one or more radiopaque markers (not shown), e.g., at one or more predetermined locations on thedistal end16 of thecatheter12 and/or on one or both balloons22. For example, a band of radiopaque material (not shown) may be provided on or under the ends of theintermediate portion28aof thedistal balloon22aor thetransverse surface28bof theproximal balloon22b, e.g., to facilitate positioning theapparatus10.
• In addition or alternatively, thestent40 may carry one or more therapeutic or other compounds (not shown) that may enhance or otherwise facilitate treatment of target location within a patient's body. For example, thestent40 may carry compounds that prevent restenosis at the target location.
• Turning toFIGS. 5A-5F, an exemplary method is shown for delivering astent40 into anostium90, e.g., using anapparatus10, which may be any of the embodiments described herein, and not necessarily limited to the embodiment shown and described with reference toFIGS. 1 and2. Theostium90 may be an opening in a wall of a first ormain body lumen92 that communicates with a second orbranch body lumen94. In an exemplary embodiment, themain body lumen92 may be the aortic root and thebranch body lumen94 may be a coronary artery. It will be appreciated that the apparatus and methods described herein may be applicable to a variety of bifurcations or branch body lumens that extend transversely, e.g., laterally or substantially perpendicular, from a main body lumen, e.g., within a patient's vasculature or other systems.
• An occlusion orother lesion96 may exist at and/or adjacent to theostium90, e.g., extending at least partially into thebranch94. Thelesion96 may include atherosclerotic plaque or other material that partially or completely occludes blood or other fluid flow between themain body lumen92 and thebranch94.
• Initially, as shown inFIG. 5A, aguidewire98 or other rail may be introduced from themain body lumen92 through theostium90 into thebranch94. As shown, thelesion96 at theostium90 partially occludes theostium90 and extends into thebranch94. Theguidewire98 may be placed using conventional methods. For example, a percutaneous puncture or cut-down may be created at a peripheral location (not shown), such as a femoral artery, carotid artery, or other entry site, and theguidewire98 may be advanced through the patient's vasculature from the entry site, e.g., atone or with the aid of a guide catheter or sheath (not shown). If thelesion96 completely occludes thebranch94, theguidewire98 may be directed through the occlusion or other devices (not shown) may be advanced over theguidewire98 or otherwise in conjunction with theguidewire98 to create a passage through thelesion96 for theguidewire98.
• After theguidewire98 is directed into thebranch94 beyond thelesion96, it may be desirable to at least partially dilate thelesion96. For example, a balloon catheter (not shown) may be advanced over theguidewire98 into and through thelesion96, whereupon a balloon or other element on the catheter may be expanded to at least partially dilate thelesion96. If desired, other procedures may also be performed at thelesion96, e.g., to soften, remove, or otherwise treat plaque or other material forming thelesion96, before thestent40 is implanted. After completing any such procedures, instruments advanced over theguidewire98 may be removed.
• Optionally, a guide catheter (not shown) may be advanced over theguidewire98 into themain body lumen92, e.g., until a distal end of the guide catheter is disposed adjacent or proximal to theostium90. The guide catheter may be used to advance one or more instruments (such as those just described) over theguidewire98 and into themain body lumen92 and/orbranch body lumen94. In addition, the guide catheter may facilitate advancement of theapparatus10 into themain body lumen92 and/or into thebranch94, in addition to or instead of theguidewire98.
• Turning inFIG. 5B, adistal end16 ofapparatus10 may be advanced over the guidewire98 (and/or through the guide catheter, not shown) from the entry site into themain body lumen92 with the balloons22 in their contracted conditions. When thedistal tip17 is adjacent to theostium90, as shown inFIG. 5C, theproximal balloon22bmay be expanded, e.g., by delivering saline, nitrogen, or other inflation media into the interior23b(see, e.g.,FIG. 2) of theproximal balloon22bfrom a syringe or other fluid source (not shown) coupled to the proximal end (also not shown) of theapparatus10. As theproximal balloon22bis expanded, asecond portion44 of thestent40 is expanded, e.g., into a flared configuration conforming to thetransverse surface28bof theproximal balloon22b.
• Turning toFIG. 5D, with thesecond portion44 flared or otherwise expanded, theapparatus10 may be advanced distally over theguidewire98 into theostium90, e.g., until thesecond portion44 contacts the wall of themain body lumen92 surrounding theostium90. As theapparatus10 is advanced, thedistal tip17 of thecatheter12 enters theostium90 and passes through thelesion96 into thebranch94, e.g., until thefirst portion42 of thestem40 is disposed within thelesion96, as shown. Optionally, if thestent40 includes one or more radiopaque markers, fluoroscopy or other external imaging may be used to ensure that thestent40 is positioned properly into theostium90 andbranch94.
• Turning toFIG. 5E, with thefirst portion42 disposed within thelesion96, thedistal balloon22amay be expanded, thereby dilating or otherwise lining thebranch94 within thelesion96. For example, as thefirst portion42 of thestent40 is expanded, plaque and/or other material defining thelesion96 may be directed radially outwardly to dilate thelesion96 to a diameter comparable to thebranch94 downstream of thelesion96. Again, if thestent40 and/orapparatus10 include one or more radiopaque markers or if contrast is delivered into themain body lumen92 and/or into thebranch94, theostium90 and orlesion96 may be imaged to confirm the position of thestent40 and/or to monitor the extent of dilation of thelesion96, e.g., until a desired diameter or other cross-section is attained.
• Optionally, additional distal force may be applied to theapparatus10, e.g., to force thesecond portion44 of thestent40 against theostium90. This pushing may cause thesecond portion44 to plastically deform further, e.g., to at least partially conform to the shape and/or contour of theostium90. This additional force may be applied before, during, or after inflation of thedistal balloon22a.
• In addition or alternatively, if theproximal balloon22bis elastically expandable, theproximal balloon22bmay be expanded initially (e.g., during the stage described with reference toFIGS. 5C and 5D) to a first enlarged configuration to allow thesecond portion44 of thestent40 to contact and/or otherwise seat into theostium90. Once thedistal balloon22ais inflated to expand thefirst portion42 of thestent40 and dilate thelesion96 to a desired extent (e.g., as described with reference toFIG. 5E), theproximal balloon22bmay be inflated further, e.g., to further expand thesecond portion44 of thestent40 or cause thesecond portion44 to conform further to the contour of theostium40. This additional expansion may further seat and/or secure thestent40, and/or to dilate theostium90. Alternatively, thedistal balloon22amay be at least partially expanded before expanding theproximal balloon22b.
• Turning toFIG. 5F, once thestent40 is expanded and/or, positioned in a desired manner, the balloons22 may be collapsed, e.g., by evacuating the inflation media using a syringe or other device (not shown at the proximal end (also not shown) of thecatheter12. The balloons22 may be deflated simultaneously or sequentially, e.g., first deflating thedistal balloon22a, and then deflating theproximal balloon22b(e.g., after applying further distal force, if desired). With the balloons22 collapsed, theapparatus10 is withdrawn from themain body lumen92 and out of the patient's body. If a guide catheter or other sheath (not shown) is used, the guide catheter or sheath may be advanced against or into theostium90 before theapparatus10 is removed, e.g., to facilitate withdrawing the balloons22 without dislodging thestent40. The guidewire98 (and/or the guide catheter or sheath, if used) may be removed before, after, or simultaneously with theapparatus10. Thus, thestent40 remains in place to dilate thelesion96.
• Although the methods described include advancing theapparatus10 into thebranch94 from themain body lumen92, it will be appreciated that, in some procedures, theapparatus10 may be advanced from thebranch94 into themain body lumen92. In such procedures, the configuration of the balloons22 may be reversed, i.e., the location of the proximal anddistal balloons22b,22amay be reversed. In addition, in some embodiments, theapparatus10 may include more than two balloons (not shown), which may be expanded independently of one another, e.g., to dilate, flare, or otherwise shape a stent during deployment in a desired manner. For example, a proximal balloon may be expanded first, and then individual balloons may be expanded sequentially, e.g., further distally along the distal end of the catheter, to expand the stent into a desired configuration within the ostium and/or branch.
• The apparatus and method described herein may allow a lesion to be dilated even if the plaque or other material extends from the branch at least partially into the ostium and/or into the main body lumen. For example, the flared shape of thesecond portion44 of thestent40 shown inFIG. 5F may substantially reduce the risk of plaque extending inwardly around thestent40 even after deployment. In contrast, a straight or unflared stent (not shown) may be deployed too far into the ostium, e.g., such that plaque within the lesion may remain exposed between the end of the stent and the main body lumen, which may at least partially occlude the ostium. Alternatively, a straight or unflared stent may be deployed such that it extends partially from the ostium into the main body lumen. This configuration may reduce the risk of at least partially occluding the ostium, but may make subsequently accessing the branch more difficult, e.g., if additional treatment is required at a later time.
• Turning toFIGS. 6A-6C, another embodiment of anapparatus110 is shown that includes acatheter112 including aproximal end114, adistal end116, and a plurality of lumens (not shown for clarity) extending therebetween, thereby defining alongitudinal axis120. A pair of balloons122 may be provided on thedistal end116, e.g., adistal balloon122aand aproximal balloon122boverlapping or otherwise adjacent thedistal balloon122a, similar to the other embodiments described herein. Thecatheter112 may include one or more lumens (not shown), e.g., an instrument lumen and an inflation lumen for each balloon122. Astent40 or other prosthesis may be carried on thedistal end116, e.g., surrounding or otherwise over the balloons122, also similar to the other embodiments described herein.
• Unlike the previous embodiments, theapparatus110 includessheath150 that at least partially covers thestent40. For example, with the balloons122 collapsed and thestent40 in a contracted configuration, thesheath150 may cover both a first ordistal portion42 and a second orproximal portion44 of thestent40, as shown inFIG. 6A. Thesheath150 may protect thestent40 and/or balloons122 during advancement of theapparatus110, and/or may provide a rounded or otherwise substantially atraumatic tip for theapparatus110, which may facilitate advancing thedistal end116 through a patient's vasculature.
• As shown, thesheath150 includes aproximal end152 that covers thestent40 and adistal end154 that is disposed distal to thestent40. Thedistal end154 may have a tapered, rounded, or other shape, e.g., to provide a substantially atraumatic tip for theapparatus110. A wire, cable, orother actuating element160 may be coupled to the distal154 and may extend proximally through or along thecatheter112 to theproximal end114. For example, thecatheter112 may include an additional lumen and/or a groove or track (not shown) that accommodates theactuating element160. Thecatheter112 may include ahandle130 on theproximal end114 including a slider or other control oractuator162 coupled to theactuating element160. As theactuator162 is directed distally, theactuating element160 may push thesheath150 distally, e.g., to expose all or a portion of thestent40.
• In an exemplary embodiment, theactuator162 may be directed from a proximal position (shown inFIG. 6A) to a first distal position, as shown inFIG. 6B, in which thefirst portion42 of thestent40 remains covered white thesecond portion44 of thestent40 is exposed. In this position, theproximal balloon122bmay be inflated, as shown, to flare or otherwise direct thesecond portion42 of thestent40 radially outwardly. Alternatively, if thesecond portion44 of thestent40 is self-expanding, thesecond portion44 may automatically flare outwardly when thesheath150 is directed to the first distal position. In this alternative, theproximal balloon122bmay be inflated to further flare or expand thesecond portion44.
• As shown inFIG. 6C, theactuator162 may also be directed to a second distal position in which thefirst portion42 of thestent40 is exposed from thesheath150. Once exposed, thedistal balloon122amay be inflated to expand thefirst portion42 of thestent40. Alternatively, thefirst portion42 of thestent40 may also be self-expanding such that thefirst portion42 at least partially expands when thesheath150 is directed to the second distal position. Thereafter, thedistal balloon122amay be inflated to further expand and/or shape thefirst portion42 of thestent40.
• Alternatively, thesheath150 may only cover thefirst portion42 of the stent40 (not shown). Optionally, an additional sheath, catheter, or other tubular member (not shown) may be provided that extends over thecatheter112 from theproximal end114 to thedistal end116 and over at least thesecond portion44 of thestent40. If desired, this tubular member may mate with theproximal end152 of thesheath150 to provide a smooth or other desired transition. In yet another alternative, one or more other constraints may be provided over thestent40, e.g., one or more filaments or other bindings (not shown) that may be wrapped around at least a portion of thestent40. Such constraint(s) may be removed from thehandle130, e.g., by directing an actuator proximally to pull the bindings apart or otherwise from around thestent40.
• Returning toFIG. 6A, during use, theapparatus110 may be provided initially with the balloons122 collapsed and thestent40 disposed over the balloons122 in a contracted configuration, similar to the previous embodiments. Thesheath150 may extend over thefirst portion42 and, optionally, over thesecond portion44 of thestent40, as show inFIG. 6A. In this configuration, theapparatus110 may be introduced to a patient's body and advanced into amain body lumen92, similar toFIG. 5B. If thesheath150 initially covers thesecond portion42 of thestent40, thesheath150 may be directed distally to expose thesecond portion42, as shown inFIG. 6B. Alternatively, if a separate tubular member covers thesecond portion44, the tubular member may be retracted proximally to uncover thesecond portion44.
• Once exposed, theproximal balloon122bmay be inflated to flare or otherwise expand thesecond portion42 of thestent40, as shown inFIG. 6B, and similar to the procedure shown and described with reference toFIG. 5C. Similar toFIG. 5D, theapparatus110 may be advanced to direct thesheath150, andfirst portion42 of thestent40 covered thereby, into theostium90 and through alesion96 at least partially into thebranch94. Turning toFIG. 6C, thesheath150 may then be directed distally to uncover thefirst portion42 of thestent40, whereupon thedistal balloon122amay be expanded, e.g., to dilate thelesion96, similar toFIG. 5E. Additional inflation and/or manipulation of the balloons122 and/orapparatus110 may be completed, similar to the previous embodiments, e.g., to enhance seating thestent40 and/or conforming thesecond portion44 to the contour of theostium90. Once the stent is properly deployed, the balloons122 may be collapsed, and theapparatus110 may be removed, leaving thestent40 to dilate thelesion96.
• It will be appreciated that elements or components shown with any embodiment herein are exemplary for the specific embodiment and may be used on or in combination with other embodiments disclosed herein. In addition, although balloons are described for expanding a stent, it will be appreciated that other expandable members may be provided on the apparatus described herein, e.g., instead of one or both of the proximal and distal balloons. For example, a pair (or more) mechanically expandable members may be provided on the distal end of a catheter that may be actuated from the proximal end of the catheter. A skin or other material may be provided that covers an expandable frame to cause the expandable members to expand to desired configurations, e.g., similar to the proximal and distal balloons described herein.
• While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the scope of the appended claims.

Claims (20)

1. An apparatus for delivering a prosthesis into an ostium of a body lumen, comprising:

an elongate member comprising a proximal end, a distal end sized for introduction into a body lumen, and first and second lumens extending between the proximal and distal ends, thereby defining a longitudinal axis;

a first expandable member on the distal end of the elongate member, the first expandable member comprising an interior communicating with the first lumen;

a second expandable member on the distal end of the elongate member, the second expandable member comprising an interior communicating with the second lumen; and

a prosthesis comprising a first portion surrounding the first expandable member and a second portion surrounding the second expandable member;

the second expandable member being expandable independently of the first expandable member for expanding the second portion to an enlarged condition while the first portion remains in a contracted condition, the first expandable member being expandable for expanding the first portion to an enlarged condition that is smaller than the second portion in its enlarged condition.

2. The apparatus ofclaim 1, further comprising a constraint for maintaining the first portion in the contracted condition while the second expandable member is expanded.

3. The apparatus ofclaim 2, wherein the constraint comprises a tubular member overlying the first portion, the tubular member being movable between a first position covering the first portion and a second position uncovering the first portion.

4. The apparatus ofclaim 3, wherein the tubular member is movable between a third position covering the second portion and the first position.

5. The apparatus ofclaim 1, wherein the second expandable member comprises a transverse surface when expanded that is disposed adjacent the first expandable member, the second portion being deformed transversely by the transverse surface as the second expandable member is expanded such that the second portion extends transversely relative to the longitudinal axis when the second portion expands to its enlarged condition.

6. The apparatus ofclaim 5, wherein the transverse surface has a generally concave shape when the second expandable member is expanded.

7. The apparatus ofclaim 6, wherein the first expandable member comprises a tapered portion that at least partially nests within the concave shape of the transverse surface as the first expandable member is expanded.

8. The apparatus ofclaim 6, wherein the second portion at least partially contacts the transverse surface of the second expandable member when the second expandable member is expanded such that an acute angle is defined between the first and second portions.

9. The apparatus ofclaim 1, wherein the first portion has a first length and the second portion has a second length, the second length being shorter than the first length.

10. The apparatus ofclaim 9, wherein the first expandable member has a length at least as long as the first length.

11. The apparatus ofclaim 1, wherein the second expandable member is disposed proximal to the first expandable member on the elongate member distal end.

12. The apparatus ofclaim 1, wherein the second expandable member is disposed immediately adjacent the first expandable member such that adjacent surfaces of the first and second expandable members contact one another as the first and second expandable members are expanded.

13. The apparatus ofclaim 1, wherein the second expandable member at least partially overlaps the first expandable member, thereby preventing gaps from forming between the first and second expandable members when the second expandable member is expanded to its enlarged condition.

14. The apparatus ofclaim 13, wherein a portion of the second expandable member is attached to a portion of the first expandable member.

15. The apparatus ofclaim 14, wherein a distal end of the second expandable member extends over and is attached to a distal end of the first expandable member.

16. The apparatus ofclaim 1, wherein the elongate member comprises a port on the proximal end and a valve for selectively connecting at least one of the first and second lumens to the port.

17. The apparatus ofclaim 16, wherein the valve is movable to a position wherein both of the first and second lumens are connected to the port such that the first and second expandable members may be expanded or collapsed substantially simultaneously.

18. An apparatus for delivering a prosthesis into an ostium of a body lumen, comprising:

an elongate member comprising a proximal end, a distal end sized for introduction into a body lumen, and a longitudinal axis extending therebetween;

a first expandable member on the distal end of the elongate member, the first expandable member being expandable from a proximal end of the elongate member, the first expandable member comprising a length for receiving a first portion of a tubular prosthesis thereon; and

a second expandable member on the distal end of the elongate member adjacent the first expandable member, a portion of the second expandable member being attached to the first expandable member, the second expandable member being expandable from a proximal end of the elongate member independently of the first expandable member for expanding the second portion to an enlarged condition while the first portion remains in a contracted condition, such that, in an enlarged condition, the second expandable member defines a transverse surface adjacent the first expandable member for expanding a second portion of the prosthesis to a flared condition to facilitate placement of the prosthesis within an ostium.

19. The apparatus ofclaim 18, further comprising a prosthesis comprising a first portion surrounding the first expandable member and a second portion surrounding the second expandable member.

20. A method for implanting a prosthesis within an ostium extending from a main lumen into a branch lumen using an elongate member comprising first and second expandable members on a distal end of the elongate member, the prosthesis comprising first and second portions surrounding the first and second expandable members, respectively, the method comprising:

directing the distal end of the elongate member into the main lumen;

expanding the second expandable member to cause the second portion of the prosthesis to expand transversely;

directing the distal end into the ostium until the expanded second portion contacts a wall of the main lumen surrounding the ostium and the first portion is disposed within the branch lumen;

expanding the first expandable member to expand the first portion of the prosthesis to contact a wall of the branch lien;

collapsing the first and second expandable members; and

withdrawing the elongate member from the branch and main lumens, leaving the prosthesis with the first portion expanded within the branch lumen and the second portion contacting the wall of the main lumen surrounding the ostium.

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