Implantable medical endoprosthesis delivery system

TECHNICAL FIELD

0001This disclosure generally relates to implantable medical endoprosthesis delivery systems and related components, as well as related methods.

BACKGROUND

0002Systems arc known for delivering medical devices, such as stents, into a body lumen. Often, such systems include a proximal portion that remains outside the body during use and a distal portion that is disposed within the body during use. The proximal portion typically includes a handle that is held by an operator of the system (e.g., a physician) during use, and the distal portion can include an outer member surrounding an inner member with a stent positioned therebetween. Generally, the operator of the system positions the distal portion within the 9lumen at a desired location (e.g., so that the stent is adjacent an occlusion). The operator can then retract the outer member to allow the stent to engage the occlusion/lumen wall. Thereafter, the operator removes the distal portion of the system from the lumen.

0003<patcit id="pcit0001" dnum="US20060058865A1"><text>US 2006/0058865 A1</text></patcit>, <patcit id="pcit0002" dnum="WO9947075A"><text>WO 99/47075</text></patcit>, <patcit id="pcit0003" dnum="WO02056798A"><text>WO 02/056798 A</text></patcit> and <patcit id="pcit0004" dnum="WO9748343A"><text>WO 97/48343</text></patcit> disclose each an implantable medical endoprosthesis delivery system in accordance with the preamble of claim 1.

SUMMARY

0004The invention is directed to an implantable medical endoprosthesis delivery system according to claim 1. Embodiments of the invention are provided in the dependent claims.

0005Embodiments can include one or more of the following advantages.

0006In some embodiments, the endoprosthesis delivery systems may enable the prosthesis to be partially deployed and or partially expanded and then retracted into the catheter to be repositioned and or removed.

0007In certain embodiments, the outer diameter of the system may be reduced, for example, to a microcatheter size to enable delivery and deployment of endoluminal devices to lumens having a small diameter.

0008In some embodiments, the delivery system may have enhanced flexibility for traveling through tortuous pathways in a subject's body.

0009Other features and advantages arc apparent from the description, drawings and claims.

DESCRIPTION OF DRAWINGS

0010<ul id="ul0001" list-style="none"><li><figref idref="f0001">FIG. 1</figref> is a partial cross-sectional view of an embodiment of an implantable medical endoprosthesis delivery system.</li><li><figref idref="f0001 f0002">FIGS. 2A-C</figref> are diagrams of an embodiment of a method.</li><li><figref idref="f0003 f0004">FIGS. 3A-C</figref> arc diagrams of an embodiment of a method.</li><li><figref idref="f0004 f0005">FIGS. 4A-C</figref> arc diagrams of an embodiment of a method.</li><li><figref idref="f0006 f0007">FIGS. 5A-C</figref> are diagrams of an embodiment of a method.</li><li><figref idref="f0007">FIG. 6</figref> is a partial cross-sectional view of an implantable medical endoprosthesis delivery system that is not part of the invention.</li><li><figref idref="f0008">FIG. 7</figref> is a partial cross-sectional view of an implantable medical endoprosthesis delivery system that is not part of the invention.</li><li><figref idref="f0008">FIG. 8</figref> is a partial cross-sectional view of an implantable medical endoprosthesis delivery system that is not part of the invention.</li><li><figref idref="f0009">FIG. 9A</figref> is an example of a guidewire that is not part of the invention.</li><li><figref idref="f0009">FIG. 9B</figref> is an example of an implantable medical endoprosthesis delivery system including the guidewire of <figref idref="f0009">FIG. 9A</figref>.</li><li><figref idref="f0010">FIG. 10A</figref> is a cross-sectional view of an example of a bumper on a delivery wire.</li><li><figref idref="f0010">FIG. 10B</figref> is a perspective view of the example of <figref idref="f0011">FIG. 11A</figref>.</li><li><figref idref="f0011">FIG. 11</figref> is a partial cross-sectional view of an implantable medical endoprosthesis delivery system that is not part of the invention.</li><li><figref idref="f0011">FIG. 12</figref> is a partial cross-sectional view of an embodiment of an implantable medical endoprosthesis delivery system.</li></ul>

0011Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

0012<figref idref="f0001">FIG. 1</figref> shows an implantable medical endoprosthesis delivery system 10 including a delivery wire 14 (e.g., a guide wire) within a catheter 16, and a stent 12 disposed between the delivery wire 14 and the catheter 16. Stent 12 is typically a self-expanding stent, and is typically contained in the catheter 16, which constrains stent 12 from expanding into its fully-expanded state. A first seating member 18 and a second seating member 20 are disposed on the delivery wire 14 between the delivery wire 14 and the stent 12. The first and second seating members 18 and 20 each have a diameter such that seating surfaces 22 on each of the first and second members 18 and 20 contacts the stent 12 while the stent 12 is disposed within the catheter 16. The seating members 18 and 20 are configured, in conjunction with the configurations of the stent 12 and the catheter 16, such that, when the stent is disposed on the seating members 18 and 20 and is disposed within the catheter 16, the stent 12 will preferentially remain disposed on the seating members 18 and 20 when catheter 16 and seating members 18 and 20 are moved with respect to each other. In certain embodiments, this may be the result of a friction fit created by the contact between the stent 12 and the seating members 18 and 20. For example, the seating surfaces 22 may have a coefficient of friction higher than that of the inner surface of the catheter 16. In certain embodiments, the seating members 18 and 20 and/or the seating surfaces 22 may be formed of a material which is at least partially deformable, for example, a soft, tacky, resilient, or elastomeric material, for example, a material having a durometer of from about 55A to about 100A (e.g., from about 60A to about 90A, from about 65A to about 85A, or from about 70A to about 80A) and/or from about 15D to about 55D (e.g., from about 20D to about 50D, from about 25D to about 45D, or from about 30D to about 40D). The durometer, or hardness, is measured in accordance with ASTM 2240. In some embodiments, the stent is at least slightly pressed into the at least partially deformable seating member and/or seating surface. Exemplary materials include rubber, synthetic rubber, latex, polyurethane/silicone combinations such as, for example, Elast-Eon™ polymers by AorTech, and other polymers such as, for example, [poly(styrene-b-. isobutylene-b-styrene)] ("SIBS"), or poly-(ether block amide), (e.g., PEBAX®).

0013In certain embodiments, the seating surface may have one or more grooves into which the stent can be at least partially deployed. The stent 12, as a result of the seating members and/or seating surfaces, remains substantially stationary with respect to the delivery wire 14 when the catheter 16 moves proximally or distally with respect to the delivery wire 14. Likewise, while when the delivery wire 14 moves proximally or distally, the stent 12 remains substantially stationary with respect to the delivery wire 14. Exemplary materials for forming the seating members 18 and 20 and/or the seating surfaces 22 include rubber, synthetic rubber, latex, polyurethane/silicone combinations such as, for example, Elast-Eon™ polymers, and other polymers such as, for example, [poly(styrene-b-. isobutylene-b-styrene)] ("SIBS"), or poly-(ether block amide), (e.g., PEBAX^®). The seating surfaces 22 may be formed of the same or a different material than the seating members 18, 20, and may make up an additional layer or component of the seating members 18, 20 or may simply be the outer surface of each seating member rather than an additional component.

0014As illustrated in <figref idref="f0001">FIG. 1</figref>, the implantable medical endoprosthesis delivery system 10 may further include a proximal bumper 26 disposed on the delivery wire 14 proximal to the stent 12. The proximal bumper 26 is configured to substantially prevent proximal movement of the stent 12 when the catheter 16 is moved proximally. The proximal bumper 26 may also serve to help in pushing the stent 12 through the catheter 16 where such is desired. A bullet-shaped tip 28 is connected to the delivery wire 14 distal of the stent 12. The tip 28 is configured to substantially prevent distal movement of the stent 12 when the catheter 16 is moved distally and to assist in the delivery of the catheter 16, preloaded with the stent 12, through body lumens to the position at which the stent 12 is to be deployed. Optionally, the delivery wire 14 can extend through the tip 28 such that a distal portion 29 of the delivery wire 14 extends beyond the tip 28 distally, for example, through a lumen (not illustrated) in the tip 28.

0015<figref idref="f0001 f0002">FIGS. 2</figref> and <figref idref="f0003 f0004">3</figref> illustrate a method utilizing implantable medical endoprosthesis delivery system 10. In general, implantable medical endoprosthesis delivery system 10 is used as follows. System 10 is positioned within a body lumen 30 (e.g., an artery) at a desired location, for example, adjacent an occlusion 35. Initially, as seen in <figref idref="f0001">FIGS. 2A</figref> and <figref idref="f0003">3A</figref>, the stent 12 is contained in an unexpanded state within the catheter 16 at a distal end 17 of the catheter 16. The catheter 16 serves to restrain the stent 12 from self-expanding at this point. The catheter 16 is withdrawn (moved proximally) as indicated by arrows <b><i>X</i></b> in <figref idref="f0002">FIGS. 2B and 2C</figref>, to expose or uncover a distal portion 12<b><i>a</i></b> of the stent 12. When the distal portion 12<b><i>a</i></b> of the stent 12 is uncovered (and thereby unrestrained from self-expansion), the distal portion self-expands towards a deployed diameter <b><i>d</i></b>, which is the diameter of the stent 12 when expanded in the body lumen 30. Typically, the deployed diameter <b><i>d</i></b> is less than the diameter to which the stent 12 would expand absent the body lumen 30. In this fashion, the stent 12 can continue to exert radial force, which can help to force open the occlusion and/or to maintain the position of the stent 12 within the body lumen 30.

0016At this point, the physician may desire to reposition the stent and/or system within lumen 30, e.g., to select a more suitable location for the stent or to correct for errors in positioning resulting from the partial deployment of the stent. Optionally, the physician may desire to entirely re-sheath and/or remove the stent (e.g., to replace it with a stent of, for example, a larger or smaller expanded diameter). Re-sheathing of the stent is possible, due at least in part to the presence of the second seating member 20. The catheter 16 can, as illustrated in <figref idref="f0002">FIG. 2C</figref>, be advanced (moved distally as indicated by arrows <b><i>Y</i></b>) to re-cover at least some of the expanded distal portion 12<b><i>a</i></b> of the stent 12 and depose the at least some of the expanded distal portion 12<b><i>a</i></b> of the stent 12 within the catheter 16.

0017Alternatively, as illustrated in <figref idref="f0004">FIG. 3C</figref>, the catheter 16 can be further withdrawn as indicated by arrows <b><i>Z</i></b> to expose or uncover the remaining proximal portion 12<b><i>b</i></b> of stent 12. Stent 12 can expand to the extent that the body lumen 30 permits once so exposed.

0018<figref idref="f0004 f0005">FIGS. 4</figref> and <figref idref="f0006 f0007">5</figref> illustrate a similar method, utilizing implantable medical endoprosthesis delivery system 10 to block the opening of an aneurysm 335 and/or strengthen a vessel at the site of ancurysm 335. System 10 is positioned within a body lumen 330 (e.g., an artery) at a desired location, for example, adjacent aneurysm 335. Initially, as seen in <figref idref="f0004">FIGS. 4A</figref> and <figref idref="f0006">5A</figref>, the stent 12 is contained in an unexpanded state within the catheter 16 at a distal end 17 of the catheter 16. The catheter 16 is withdrawn (moved proximally) as indicated by arrows X in <figref idref="f0005">FIGS. 4B</figref> and <figref idref="f0006">5B</figref>, to expose or uncover a distal portion 12a of the stent 12. When the distal portion 12<b><i>a</i></b> of the stent 12 is uncovered (and thereby unrestrained from self-expansion), the distal portion self-expands towards a deployed diameter <b><i>d</i></b>, which is the diameter of the stent 12 when expanded in the body lumen 330. At this point, the physician may desire to reposition the stent and/or system within lumen 330 or to entirely re-sheath and remove the stent and replace it with a stent of, for example, a larger or smaller expanded diameter. The catheter 16 can, as illustrated in <figref idref="f0005">FIG. 4C</figref>, be advanced (moved distally as indicated by arrows <b><i>Y</i></b>) to re-cover at least some of the expanded distal portion 12<b><i>a</i></b> of the stent 12 and depose the at least some of the expanded distal portion 12<b><i>a</i></b> of the stent 12 within the catheter 16.

0019Should the physician determine that the stent 12 is properly positioned within lumen 330, as illustrated in <figref idref="f0007">FIG. 5C</figref>,the catheter 16 can be further withdrawn as indicated by arrows <b><i>Z</i></b> to expose or uncover the remaining proximal portion 12b of stent 12. Stent 12 can then expand to the extent that the body lumen 330 permits once so exposed, thereby at least partially occluding the opening 336 to the aneurysm 335.

0020In the example illustrated in <figref idref="f0007">FIG. 6</figref>, an implantable medical endoprosthesis delivery system 100 has a delivery wire 114 within catheter 116, and a stent 112 disposed between the delivery wire 114 and the catheter 116. A coating 118 is disposed on the delivery wire 114 (e.g., a guide wire) between the delivery wire 114 and the stent 112, with a coating surface 122 contacting the stent 112. In general, the coating surface 122 is formed of a material that presses against or into the stent to force the stent to travel longitudinally, relative to the catheter, with the delivery wire. The coating may in certain embodiments be formed of a liquid or fluid material placed on or applied to the exterior of the wire and allowed to harden on the exterior of the wire, for example, sprayed on, brushed on, shrink-wrapped, and/or hot-dipped. Generally, the thickness of the coating is selected based on the catheter inner diameter, stent thickness, and delivery wire diameter. In some embodiments, the coating has a thickness of no less than about 0.05 mm (e.g., no less than about 0.10 mm, no less than about 0.15 mm, or no less than about 0.20 mm) and/or no more than about 0.25 mm (e.g., no more than about 0.20 mm, no more than about 0.15 mm, or no more than about 0.10 mm).

0021The coating may in certain embodiments be a sleeve or a cylindrical plug of material having a central bore for receiving the delivery wire. The sleeve or plug grips the delivery wire with sufficient force to ensure that it travels with the delivery wire. The coating may be a polymer coating, for example a thermoplastic coating (e.g., ElastEon™) or may be a rubber, synthetic rubber, SIBS, or poly-(ether block amide) (e.g., PEBAX^®). The coating thickness is generally selected such that the coating will contact the endoprosthesis while the prosthesis is disposed within the delivery catheter and may be, for example, no less than about 3 µm thick (e.g., no less than about 50 µm thick, no less than about 100 µm thick, no less than about 150 µm thick, no less than about 200 µm thick, no less than about 250 µm thick, no less than about 300 µm thick, no less than about 350 µm thick, no less than about 400 µm thick, no less than about 450 µm thick, no less than about 500 µm thick, no less than about 550 µm thick, no less than about 600 µm thick, or no less than about 650 µm thick) and/or no more than about 700 µm thick (e.g., no more than about 650 µm thick, no more than about 600 µm thick, no more than about 550 µm thick, no more than about 500 µm thick, no more than about 450 µm thick, no more than about 400 µm thick, no more than about 350 µm thick, no more than about 300 µm thick, no more than about 250 µm thick, no more than about 200 µm thick, no more than about 150 µm thick, no more than about 100 µm thick, or no more than about 50 µm thick). This provides for delivery wire/coating combinations having a diameter of no less than about 0.1 mm (e.g., no less than about 0.2 mm, no less than about 0.4 mm, no less than about 0.6 mm, no less than about 0.8 mm, or no less than about 1 mm) and/or no more than about 1.2 mm (e.g., no more than about I mm, no more than about 0.8 mm, no more than about 0.6 mm, no more than about 0.4 mm, or no more than about 0.2 mm). The coating 118 and the coating surface 122 may be formed of the same or of different materials. The coating 118 and the coating surface 122 may be contiguous, whereby the coating surface is formed of the outward-facing surface of the coating. The coating and coating surface arc configured to retain the stent 112 in a substantially motionless position relative to the delivery wire 114 when the catheter 116 is moved proximally or distally and/or when the delivery wire 114 is moved proximally or distally.

0022<figref idref="f0008">FIGS. 7 and 8</figref> illustrate other examples of implantable medical endoprosthesis delivery systems. An implantable medical endoprosthesis delivery system 150, illustrated in <figref idref="f0006 f0007">FIG. 5</figref>, has a delivery wire 154 within catheter 156, and a stent 152 disposed between the delivery wire 154 and the catheter 156. Windings 158 are disposed on the delivery wire 154 between the delivery wire 154 and the stent 152. The windings may be formed of a single strand of winding material, or optionally may be formed of multiple strands of winding material, for example, two, three or more strands of winding material. The windings 158 may be formed from a winding material including a resilient material, e.g., a polymer, for example, ElastEon™, poly-(ether block amide), (e.g., PEBAX^®) or SIBS. The windings may be formed from an elastomeric material, e.g., a material having a durometer of at from about 65A to about 55D. The windings may extend substantially along the full length of the endoprosthesis, or may extend along a portion of the endoprosthesis. Multiple sections of windings may be included, e.g., two, three or more sections each supporting a portion of the endoprosthesis. The windings 158 are sized to provide a windings diameter sufficient to apply a radial force to the stent 152 so that the stent 152 forms a friction fit with the catheter 156 to retain the stent 152 in a substantially motionless position relative to the delivery wire 154 when the catheter 156 is moved proximally or distally and/or when the delivery wire 154 is moved proximally or distally. In certain examples, the windings may form a mechanical grip with the struts of the stent, whereby the struts arc at least partially disposed within the spaces between the windings.

0023In general, the windings may in certain examples have an average width (e.g., diameter, when the windings arc cylindrical) of no less than about 3 µm (e.g., no less than about 50 µm, no less than about 100 µm, no less than about 150 µm, no less than about 200 µm, no less than about 250 µm, no less than about 300 µm, no less than about 350 µm, no less than about 400 µm, no less than about 450 µm, no less than about 500 µm, no less than about 550 µm, no less than about 600 µm, or no less than about 650 µm) and/or no more than about 700 µm (e.g., no more than about 650 µm, no more than about 600 µm, no more than about 550 µm, no more than about 500 µm, no more than about 450 µm, no more than about 400 µm, no more than about 350 µm, no more than about 300 µm, no more than about 250 µm, no more than about 200 µm, no more than about 150 µm, no more than about 100 µm, or no more than about 50 µm). The windings may in certain embodiments have an average pitch (the length, measured longitudinally, of one full turn of the windings around the delivery wire) of no more than about 10 mm (e.g., no more than about 1 mm, no more than about 0.1 mm. or no more than about 0.05 mm) and/or no less than about 0.025 mm (e.g., no less than about 0.05 mm, no less than about 0.1 mm, or no less than about 1 mm). In certain embodiments, the windings may be placed on the delivery wire such that they are spaced apart from each other, which may impart greater flexibility to the delivery system. For example as illustrated in <figref idref="f0008">FIG. 8</figref>, the ratio of an average pitch <b><i>p</i></b> of the windings to an average width <i>w</i> of the windings may be at least about 2 (e.g., at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5), and may be at most about 5 (e.g., at most about 4.5, at most about 4, at most about 3.5, at most about 3, at most about 2.5), and may be between about 2 and about 5 (e.g., between about 2.5 and about 4.5, between about 3 and about 4).

0024The windings in certain examples extend for an overall length of no more than about 35 mm (e.g., no more than about 30 mm, no more than about 25 mm, or no more than about 20 mm) and/or no less than about 15 mm (e.g., no less than about 20 mm, no less than about 25 mm, or no less than about 30 mm). In some examples, multiple sections of windings can be employed. Where multiple sections of winding are included, each section may have the same or different winding pitch, winding width, and/or ratio of the average pitch to the average width of the windings.

0025<figref idref="f0009">FIG. 9A</figref> shows a delivery wire 200 (e.g., a guidewire) which includes a wire 202 having a first portion 204, a second portion 206, and a third portion 208 disposed between the first and second portions 204 and 206, respectively. Windings 210 are disposed on the first portion 204 and the second portion 206 but the third portion 208 has no windings disposed thereupon. The windings 210 are typically formed of a material that is different from the material that forms the wire 202. Generally, windings 210 may be any suitable material for achieving the desired stiffness/flexibility of the delivery wire, and may include, for example, metals, metal oxides, polymers, or plastics. The windings 210 are generally sized to provide stent-contacting surfaces 214 that contact both ends of stent 212 so that the stent 212 is retained in a substantially motionless position relative to the delivery wire 200 when the catheter 216 is moved proximally or distally and/or when the delivery wire 200 is moved proximally or distally. In certain embodiments, the windings may have a diameter of no less than about 0.02 mm (e.g., no less than about 0.025 mm, no less than about 0.03 mm, no less than about 0.05 mm, or no less than about 1 mm) and/or no more than about 1.5 mm (e.g., no more than about 1 mm, no more than about 0.05 mm, no more than about 0.03 mm, no more than about 0.025 mm, or no more than about 0.02 mm). This provides for delivery wires having an overall diameter, inclusive of the windings, of no less than about 0.1 mm (e.g., no less than about 0.2 mm, no less than about 0.3 mm, no less than about 0.4 mm, no less than about 0.5 mm, no less than about 0.6 mm, no less than about 0.7 mm, no less than about 0.8 mm, or no less than about 0.9 mm) and/or no more than about 1.0 mm (e.g., no more than about 0.9 mm, no more than about 0.8 mm, no more than about 0.7 mm, no more than about 0.6 mm, no more than about 0.5 mm, no more than about 0.4 mm, no more than about 0.3 mm, no more than about 0.2 mm, or no more than about 0.1 mm). The third portion 208 is generally configured to be at least as long as or slightly longer than the implantable endoprosthesis that is to be disposed around the third portion 208. For example, in some embodiments, the third portion has a length of at least about 0.5 cm (e.g., at least about 1 cm, at least about 2 cm, at least about 3 cm, at least about 4 cm, at least about 5 cm, at least about 6 cm, at least about 8 cm, or at least about 10 cm) and or no more than about 15 cm (e.g., no more than about 10 cm, no more than about 8 cm, no more than about 6 cm, no more than about 5 cm, no more than about 4 cm, no more than about 3 cm, no more than about 2 cm, or no more than about 1 cm).

0026An implantable medical endoprosthesis delivery system 220 including the delivery wire 200 is illustrated in <figref idref="f0009">FIG. 9B</figref>. A stent 212 is disposed between the first portion 204 of the delivery wire 200 and a catheter 216. The windings 210 each have a stent-contacting surface 214 disposed on the end of the windings 210 that face the third section 208 of the delivery wire 200. The third portion 208 is sized to permit rotation or torque of the delivery wire 200 while applying substantially no torque to the stent 212.

0027In some examples, the delivery wire may further include a proximal bumper, a distal tip or bumper, or both, on the first and or second portions and typically at the edge of the proximal and distal portions nearest the intermediate portion. Such bumper or bumpers may contact the stent in lieu of a stent-contacting surface of the windings, and would serve the same purpose, namely to hold the stent substantially motionless (in a proximal or distal direction) relative to the delivery wire. In some embodiments, the third portion of the delivery wire may have windings disposed thereupon, provided that the diameter of the third portion, inclusive of the optional windings, remains small enough to permit the delivery wire to be torqued without imparting torque to the stent. Such a configuration may be desirable where additional stiffness is desired in the delivery wire, for example, where the endoprosthesis is particularly long (e.g. at least 25 mm long, at least 30 mm long, at least 35 mm long, at least 40 mm long, or at least 45 mm long).

0028<figref idref="f0010">FIGS. 10A and 10B</figref> illustrate a delivery wire 400 (e.g., a guidewire) including a wire 402 having a member 404 (e.g., a seating member or a bumper) disposed thereon, in which the wire 402 can be rotated without causing the member 404 to rotate. The member 404 has a lumen 406 through which the wire 402 passes. The lumen 406 has a diameter d' that is large enough to allow the wire 402 to rotate within the lumen .406 without applying substantial amounts of (e.g., without applying any) torque to the member 404 (e.g., d' is larger than a diameter d" of the wire 402). A pair of sub-bumpers 410 are attached (e.g., adhered) to the wire 402 at positions proximal and distal the member 404. The sub-bumpers 410 each have a diameter d'" that is larger than the diameter d' of the lumen 406 in member 404, such that the sub-bumpers can prevent the member 404 from moving proximally or distally along the wire 402 beyond either of the sub-bumpers 410. In this fashion, the member 404 is retained laterally at a single position on wire 402, but is not subject to torque when wire 402 is rotated (e.g., to steer wire 402 through a body lumen). The sub-bumpers 410 are attached to the wire 402 such that the sub-bumpers 410 move laterally and rotationally with the wire 402. The diameter d'" of the sub-bumpers 410 is smaller than an outer diameter of the member 404.

0029<figref idref="f0011">FIG. 11</figref> illustrates an implantable medical endoprosthesis delivery system 420 that includes bumpers stent seating members that are not subject to torque when the delivery wire is rotated. The system 420 includes a pair of bumpers 424, each having a lumen 426 through which a wire 422 passes, the lumen 426 having a diameter larger than the diameter of the wire 422. The bumpers are held in place laterally by two pairs of sub-bumpers 430, each attached to the wire 422 such that they move laterally and rotationally along with the wire 422. The sub-bumpers 430 have a diameter larger than the diameter of the lumen 426 of the bumpers 424. The bumpers 424 are spaced apart from one another such that a stent 450 can be located between the bumpers 424. The stent 450 and the delivery wire 422 are contained in a catheter 428, which constrains the stent 450 from expanding into its fully-expanded state.

0030A seating member 438 is disposed between the wire 422 and the stent 450. The seating member 438 has a lumen 440 through which the wire 422 passes, the lumen 440 having a diameter larger than the diameter of the wire 422. The seating member 438 is held in place laterally by two pairs of sub-bumpers 442, each attached to the wire 422 such that they move laterally and rotationally along with the wire 422. The sub-bumpers 442 have a diameter larger than the diameter of the lumen 440 of the seating member 438.

0031The seating member 438 has a diameter of sufficient size such that an outer (seating) surface 444 on the seating member 442 contacts the stent 450 while the stent 450 is disposed within the catheter 428. The bumpers 424 each have a diameter such that the bumper can contact a proximal edge 452 or a distal edge 454 of the stent 450. Each of the sub-bumpers 430 and 442 arc sized to be larger than the lumen of the member (bumper 424 or seating member 438) that they abut while being small enough to avoid subjecting either the stent 450 or the catheter 428 to torque upon rotation of the wire 422.

0032In certain examples, an implantable medical endoprosthesis may be delivered using a delivery catheter rather than a delivery wire. One such embodiment is illustrated in <figref idref="f0011">FIG. 12</figref>, in which an implantable medical endoprosthesis delivery system 50 includes a delivery catheter 54 within outer catheter 56, and a stent 52 disposed between the delivery catheter 54 and the outer catheter 56. A first seating member 58 and second seating member 60 arc disposed on the delivery catheter 54 between the delivery catheter 54 and the stent 52. The first and second seating members 58 and 60 each have a diameter such that seating surfaces 62 on each of the first and second members 58 and 60 contacts the stent 52. The first and second seating members 58 and 60 are configured such that, when the outer catheter 56 moves proximally or distally with respect to the delivery catheter 54, the stent 52 remains substantially stationary with respect to the delivery catheter 54, while when the delivery catheter 54 moves proximally or distally, the stent 52 remains substantially stationary with respect to the delivery catheter 54. The first and second seating members 58 and 60 may be made of any of the materials disclosed above, and may include seating surfaces in accordance with those described above. A proximal bumper 66 is disposed on the delivery catheter 54 proximal to the stent 52 and is configured to substantially prevent proximal movement of the stent 52 when the outer catheter 56 is moved proximally. The proximal bumper 66 may also serve to help in pushing the stent 52 through the outer catheter 56 where such is desired. A bullet-shaped tip 68 is connected to a distal end 55 of the delivery catheter 54 distal of the stent 52 and is configured to substantially prevent distal movement of the stent 52 when the outer catheter 56 is moved distally. The bullet-shaped tip 68 includes a tip lumen 69 extending longitudinally therethrough to form, in conjunction with a lumen 53 in delivery catheter 54, a lumen, e.g., through which a guidewire (not here illustrated) can extend.

0033While certain embodiments have been described, others are possible.

0034For example, in certain embodiments, a seating member may extend distally beyond the distal end of the delivery device and itself form a tip, e.g., a bullet shaped tip.

0035As another example, the delivery wire can in certain embodiments comprise a metal, an alloy (e.g., a stainless steel or Nitinol), or a polymer (e.g., a plastic).

0036As another example, in certain embodiments, the delivery member can be formed of a tube, e.g., a tube having a spiral tube, attached (e.g., by adhesive or by weld) to the outside of the tube. As another example, the delivery member can be a slotted hypotube, a rigid or semirigid tube having slots cut into it (e.g., by mechanical cutting or laser ablation). Such a delivery device can include an inner lumen while maintaining more flexibility than an unslotted tube.

0037As another example, in certain embodiments, the catheter or sheath in which the endoprosthesis is contained may be a microcatheter, e.g., the catheter may have a diameter of not more than about 5 french (e.g., not more than about 4 french, not more than about 3.5 french, not more than about 3 french, not more than about 2.5 french, not more than about 2.3 french, not more than about 2 french).

0038As another example, in certain embodiments, an adhesive may be interposed between the delivery wire or catheter and the seating members, coatings, and/or windings to ensure that the seating device travels with the delivery device.

0039As another example, in certain embodiments, a seating member can be a balloon that could be at least partially inflated to achieve a friction fit between itself and the endoprosthesis. Such a balloon could optionally remain uninflated unless retraction of a partially-deployed endoprosthesis was desired, at which point it could be at least partially inflated to achieve a friction fit.

0040As another example, in certain embodiments, the endoprostheses, delivery wires, catheters and/or guidewires may include one or more radiopaque materials, for example, one or more bands of radiopaque materials.

0041As another example, in certain embodiments, any of the seating components (seating members, seating surfaces, coatings, wrappings, windings) the seating members can comprise a resilient and/or deformable material such that the endoprosthesis can press into it, forming a releasable mechanical grip with the seating member. For example, the seating component may have a durometer of no more than 55D (e.g., no more than 65A). Exemplary resilient materials include, for example, ElastEon™, SIBS, or poly-(ether block amide), (e.g., PEBAX^®).

0042As another example, the seating surface may have a tacky consistency to which the endoprosthesis adheres, provided that substantially no material transfers from the seating surface to the stent. Exemplary tacky seating surfaces include ElastEon™, SIBS, or poly-(ether block amide), (e.g., PEBAX^®).

0043As yet another example, while certain embodiments have been shown and/or described without a distal tip or a proximal bumper, embodiments generally can have a distal tip (e.g., a bullet-shaped distal tip) and/or a proximal bumper.