US20140058502A1 - Integrated heart valve delivery system - Google Patents

Abstract

Embodiments of the present disclosure provide a delivery apparatus for delivering a prosthetic heart valve to a native valve site via the human vasculature without the need for a separate introducer sheath. The delivery apparatus is particularly well-suited for advancing a prosthetic valve through the aorta (i.e., in a retrograde approach) for replacing a stenotic aortic valve.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. patent application Ser. No. 11/852,977, filed Sep. 10, 2007, now U.S. Pat. No. 8,568,472, which claims the benefit of U.S. Patent Application No. 60/843,470, filed Sep. 8, 2006, the entire disclosures of which are incorporated herein by reference.
FIELD
• The present application concerns embodiments of a system for delivering a prosthetic valve to a heart via the patient's vasculature.
BACKGROUND
• Endovascular delivery catheters are used to implant prosthetic devices, such as a prosthetic valve, at locations inside the body that are not readily accessible by surgery or where access without surgery is desirable. The usefulness of delivery catheters is largely limited by the ability of the catheter to successfully navigate through small vessels and around tight bends in the vasculature, such as around the aortic arch.
• Known delivery apparatuses include a balloon catheter having an inflatable balloon that mounts a prosthetic valve in a crimped state and a retractable cover that extends over the valve to protect the interior walls of the vasculature as the valve is advanced to the implantation site. Various techniques have been employed to adjust the curvature of a section of the delivery apparatus to help “steer” the valve through bends in the vasculature. The balloon catheter may also include a tapered tip portion mounted distal to the balloon to facilitate tracking through the vasculature. The tip portion, however, increases the length of the relatively stiff, non-steerable section of the apparatus. Unfortunately, due to the relatively long stiff section, successful delivery of a prosthetic valve through tortuous vasculature, such as required for retrograde delivery of a prosthetic aortic heart valve, has proven to be difficult.
• A known technique for adjusting the curvature of a delivery apparatus employs a pull wire having a distal end fixedly secured to the steerable section and a proximal end operatively connected to a rotatable adjustment knob located outside the body. Rotation of the adjustment applies a pulling force on the pull wire, which in turn causes the steerable section to bend. The rotation of the adjustment knob produces less than 1:1 movement of the pull wire; that is, rotation of the knob does not produce equal movement of the steerable section. To facilitate steering, it would be desirable to provide an adjustment mechanism that can produce substantially 1:1 movement of the steerable section.
• It is also known to use an introducer sheath for safely introducing a delivery apparatus into the patient's vasculature (e.g., the femoral artery). An introducer sheath has an elongated sleeve that is inserted into the vasculature and a seal housing that contains one or more sealing valves that allow a delivery apparatus to be placed in fluid communication with the vasculature with minimal blood loss. A conventional introducer sheath typically requires a tubular loader to be inserted through the seals in the sheath housing to provide an unobstructed path through the seal housing for a valve mounted on a balloon catheter. A conventional loader extends from the proximal end of the introducer sheath, and therefore decreases the available working length of the delivery apparatus that can be inserted through the sheath and into the body.
• Accordingly, there remains a need in the art for improved endovascular systems for implanting valves and other prosthetic devices.
SUMMARY
• Certain embodiments of the present disclosure provide a heart valve delivery apparatus for delivery of a prosthetic heart valve to a native valve site via the human vasculature. The delivery apparatus is particularly suited for advancing a prosthetic valve through the aorta (i.e., in a retrograde approach) for replacing a stenotic native aortic valve.
• The delivery apparatus in particular embodiments includes a balloon catheter having an inflatable balloon which mounts a crimped valve for delivery through the patient's vasculature. The delivery apparatus can include a guide, or flex, catheter having a shaft that extends over the shaft of the balloon catheter. The guide catheter shaft has a steerable section, the curvature of which can be adjusted by the operator to facilitate navigation of the delivery apparatus around bends in the vasculature. The delivery apparatus also can include a nose catheter having a shaft that extends through the balloon catheter shaft and a nose piece located distally of the valve. The nose piece desirably has a tapered outer surface and is made of a flexible material to provide atraumatic tracking through the arteries and a stenotic native valve. The nose piece desirably has an internal bore that is dimensioned to receive at least a distal end portion of the deflated balloon during delivery of the valve.
• By inserting a portion of the balloon into the nose piece, the length of the non-steerable section of the delivery apparatus can be reduced (e.g., by about 1.5 to 2.0 cm in some examples), which greatly enhances the ability of the delivery apparatus to track through the aortic arch with little or no contact between the end of the delivery apparatus and the inner walls of the aorta. Once the delivery apparatus has been advanced to the implantation site, the nose catheter can be moved distally relative to the balloon catheter to withdraw the balloon from the nose piece so as not to interfere with inflating the balloon.
• The guide catheter shaft can be provided with a cover at its distal end to cover a portion of the balloon and/or the valve that is not already covered by the nose piece. In particular embodiments, the cover extends over the remaining portion of the balloon and the valve that is not covered by the nose piece. In this manner, the entire outer surface of the valve and the balloon are shielded by the nose piece and the cover. Consequently, an introducer sheath need not be used to introduce the delivery apparatus into the patient's vasculature. Unlike an introducer sheath, the cover need only be in contact with the femoral and iliac arteries for only a short period of time, and thus minimizes the possibility of trauma to these vessels. Further, by eliminating the introducer sheath, the maximum diameter of the system can be reduced, and therefore it is less occlusive to the femoral artery.
• In one variation of the delivery apparatus, the nose piece has an internal bore dimensioned to receive the entire valve and substantially the entire balloon during delivery of the valve. Thus, in this embodiment, the cover attached to the end of the guide catheter need not be provided. In another variation, the cover of the guide catheter extends completely over the valve and the balloon, and the nose catheter is not provided. The cover can be an expandable mesh basket that can collapse around the valve and the balloon to provide a smooth tracking profile. The mesh basket can be expanded by the operator, such as by pulling one or more pull wires, which dilates a distal opening in the mesh basket permitting the balloon and the valve to be advanced from the basket for deployment.
• As noted above, the guide catheter desirably has a steerable section that can be deflected or bent by the operator to assist in tracking the delivery apparatus around bends in the vasculature. In certain embodiments, the guide catheter can be provided with a manually operated adjustment mechanism that produces substantially 1:1 movement of the steerable section. To such ends, the adjustment mechanism can include a pivotable lever that is operatively coupled to the steerable section via a pull wire extending through a lumen in the guide catheter shaft. Pivoting the lever operates a pulley, which retracts the pull wire, producing substantially 1:1 movement of the steerable section. Pivoting the lever in the opposite direction releases tension in the pull wire, and the resiliency of the steerable section causes the steerable section to return to its normal, non-deflected shape.
• In cases where an introducer sheath is used to assist in inserting the delivery apparatus into the patient's vasculature, the introducer sheath can be provided with an integrated loader tube that extends into the seal housing of the sheath. The loader tube is connected to an end piece coupled to the distal end of the seal housing. The end piece is moveable along the length of the seal housing between a first, extended position where the loader tube is spaced from the sealing valves in the seal housing and a second, retracted position where the loader tube extends through the sealing valves to provide an unobstructed pathway for a valve mounted on a balloon catheter. Because the loader tube does not extend behind the end piece, the loader tube does not decrease the available working length of the delivery apparatus that can be inserted through the sheath and into the vasculature.
• In one representative embodiment, an apparatus for delivering a prosthetic valve through the vasculature of a patient comprises a balloon catheter, a guide catheter, and a nose catheter configured to move longitudinally relative to each other. The balloon catheter comprises an elongated shaft and a balloon connected to a distal end portion of the shaft, the balloon being adapted to carry the valve in a crimped state and being inflatable to deploy the valve at an implantation site in the patient's body. The guide catheter comprises an elongated shaft extending over the balloon catheter shaft, the shaft of the guide catheter comprising a steerable section. The guide catheter further comprises an adjustment mechanism operatively coupled to the steerable section. The adjustment mechanism is configured to adjust the curvature of the steerable section and the portion of the balloon catheter shaft extending through the steerable section. The nose catheter comprises an elongated shaft extending through the balloon catheter shaft and a nose piece connected to a distal end of the nose catheter shaft. The nose piece has an internal bore adapted to receive at least a distal end portion of the balloon in a deflated state during delivery of the valve.
• In another representative embodiment, a method of implanting a prosthetic valve at an implantation site in a patient's body comprises placing the valve on an inflatable balloon of a balloon catheter of a delivery apparatus and inserting at least a distal end portion of the balloon in a nose piece of a nose catheter of the delivery apparatus. The balloon catheter and the nose catheter are then inserted into the body and advanced through the patient's vasculature. At or near the implantation site, the nose catheter is moved distally relative to the balloon catheter to uncover the portion of the balloon inside the nose piece, and thereafter the valve can be deployed at the implantation site by inflating the balloon.
• In another representative embodiment, a method of implanting a prosthetic valve at an implantation site in a patient's body comprises placing the valve in a crimped state on the distal end portion of an elongated delivery apparatus and advancing the delivery apparatus through the patient's vasculature. Subsequent to the act of advancing the delivery apparatus, the crimped valve is moved onto an inflatable balloon on the distal end portion of the delivery apparatus and then deployed at the implantation site by inflating the balloon.
• In yet another representative embodiment, an apparatus for delivering a prosthetic valve through the vasculature of a patient comprises a balloon catheter and a nose catheter. The balloon catheter comprises an elongated shaft, a balloon connected to a distal end portion of the shaft, and a tapered wedge connected to the distal end portion adjacent the balloon. The nose catheter comprises an elongated shaft extending through the shaft of the balloon catheter, the balloon, and the wedge. The nose catheter further includes a nose piece connected to a distal end of the nose catheter shaft. The valve can be mounted in a crimped state between the nose piece and the wedge. The nose piece can be retracted proximally to push the valve over the wedge and onto the balloon, with the wedge partially expanding the valve before it is placed on the balloon.
• In another representative embodiment, a guide catheter for an endovascular delivery apparatus comprises an elongated shaft having a steerable section, a handle comprising a pivotable lever, and a pull wire. The pull wire has a proximal end portion coupled to the lever and a distal end portion fixedly secured to the steerable section such that pivoting movement of the lever applies a pulling force on the pull wire to cause the steerable section to bend.
• In another representative embodiment, an endovascular delivery apparatus comprises a balloon catheter comprising an elongated shaft and a balloon connected to a distal end portion of the shaft. A guide catheter comprises an elongated shaft comprising an inner polymeric tubular liner having a lumen sized to permit insertion of the balloon and the balloon catheter shaft therethrough. The shaft further comprises a braided metal layer surrounding the tubular liner, and an outer polymeric layer surrounding the braided metal layer.
• In another representative embodiment, a method for making a catheter comprises forming an inner tubular layer from a polymeric material, the inner tubular layer having a lumen dimensioned to allow a balloon of a balloon catheter to pass therethrough, forming a tubular pull wire conduit from a polymeric material, placing the conduit and the inner tubular layer side-by-side in a parallel relationship relative to each other, forming a braided metal layer around the conduit and the inner tubular layer, and forming an outer polymeric layer around the braided metal layer.
• In another representative embodiment, an introducer sheath comprises an elongated tubular sleeve having a lumen and adapted to be inserted into a patient's vasculature, a seal housing comprising an inner bore in communication with the lumen of the sleeve and one or more sealing valves housed in the bore, and an end piece coupled to the sealing housing opposite the sleeve. The end piece comprises a loader tube extending into the bore and is moveable along a length of the seal housing to move the loader tube from a first position spaced from the one or more sealing valves to a second position wherein the loader tube extends through the sealing valves.
• The foregoing and other features and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is side view of an endovascular delivery apparatus for implanting a prosthetic valve, according to one embodiment.
• FIG. 2A is side view of the balloon catheter of the delivery apparatus ofFIG. 1, shown partially in section.
• FIG. 2B is an enlarged, cross-sectional view of the balloon catheter shown inFIG. 2A, taken along the length of the catheter.
• FIG. 3A is a cross-sectional view of the guide catheter of the delivery apparatus ofFIG. 1, taken along a plane extending along the length of the guide catheter.
• FIG. 3B is a cross-sectional view of the guide catheter, taken along a plane that is perpendicular to the plane defining the cross-section view shown inFIG. 3A.
• FIG. 4A is a cross-sectional view of the nose catheter of the delivery apparatus shown inFIG. 1, taken along the length of the nose catheter.
• FIG. 4B is an enlarged, cross-sectional view of the nose catheter.
• FIGS. 5A and 5B are cross-sectional and perspective views, respectively, of a slide nut used in the handle portion of the guide catheter.
• FIGS. 6A and 6B are perspective and side views, respectively, of an inner sleeve used in the handle portion of the guide catheter.
• FIG. 7A is a cross-sectional view of a guide catheter, according to one embodiment, taken along the length thereof.
• FIG. 7B is a transverse cross-sectional view of the guide catheter shown inFIG. 7A.
• FIG. 7C is an enlarged, longitudinal cross-sectional view of the distal end portion of the guide catheter shown inFIG. 7A.
• FIGS. 8A-8C are cross-sectional views of the distal end portion of the delivery apparatus ofFIG. 1, illustrating the operation of the same for implanting a prosthetic valve.
• FIG. 9 is side view of an endovascular delivery apparatus for implanting a prosthetic valve, according to another embodiment.
• FIG. 10A is a side view of the introducer sheath of the deliver apparatus shown inFIG. 9.
• FIG. 10B is a side view of the introducer sheath ofFIG. 10A shown partially in section.
• FIG. 10C is an end view of the introducer sheath ofFIG. 10A.
• FIG. 11 is a perspective view of an alternative embodiment of a guide catheter.
• FIG. 12 is a top plan view of the guide catheter ofFIG. 11.
• FIG. 13 is a side elevation view of the guide catheter ofFIG. 11.
• FIG. 14 is a perspective, exploded view of the guide catheter ofFIG. 11.
• FIG. 15 is a partial, cross-sectional view of the guide catheter ofFIG. 11.
• FIGS. 16A and 16B are perspective views of a pulley used in the guide catheter ofFIG. 11.
• FIG. 17 is a perspective view of a lever portion used in the guide catheter ofFIG. 11.
• FIGS. 18A and 18B are partial, cross-sectional views of the guide catheter ofFIG. 11 illustrating the operation of an adjustable lever for adjusting the curvature of the guide catheter.
• FIG. 19A is a perspective view of the distal end portion of alternative embodiment of a nose catheter.
• FIGS. 19B and 19C are cross-sectional views illustrating the operation of the nose catheter shown inFIG. 19A.
• FIG. 20A is a side elevation view of the distal end portion of a delivery apparatus, according to another embodiment.
• FIG. 20B is a transverse cross-sectional view of the guide catheter of the delivery apparatus ofFIG. 20A.
• FIGS. 21A-21C are cross-sectional views of an alternative embodiment of a delivery apparatus, illustrating the operation of the same for implanting a prosthetic valve.
• FIGS. 22A and 22B are cross-sectional views of the distal end portion of another embodiment of a delivery apparatus.
• FIG. 23A shows a cross-sectional view of another embodiment of an introducer sheath and an exemplary delivery apparatus that can be introduced into a patient's vasculature via the sheath.
• FIG. 23B is a cross-sectional view of the introducer sheath ofFIG. 23A after insertion of the delivery apparatus into the sheath.
• FIGS. 24A-24B are cross-sectional views of another embodiment of a delivery apparatus.
• FIGS. 25A-25E schematically illustrate another embodiment of a delivery apparatus.
• FIGS. 26A-26E schematically illustrate another embodiment of an introducer sheath.
DETAILED DESCRIPTION
• FIG. 1 shows adelivery apparatus10 adapted to deliver a prosthetic heart valve12 (e.g., a prosthetic aortic valve) to a heart, according to one embodiment. Theapparatus10 generally includes a steerable guide catheter14 (also referred to as a flex catheter), aballoon catheter16 extending through theguide catheter14, and anose catheter18 extending through theballoon catheter16. Theguide catheter14, theballoon catheter16, and thenose catheter18 in the illustrated embodiment are adapted to slide longitudinally relative to each other to facilitate delivery and positioning of thevalve12 at an implantation site in a patient's body, as described in detail below.
• Theguide catheter14 includes ahandle portion20 and an elongated guide tube, or shaft,22 extending from thehandle portion20. Theballoon catheter16 includes aproximal portion24 adjacent thehandle portion20 and anelongated shaft26 that extends from theproximal portion24 and through thehandle portion20 and theguide tube22. Aninflatable balloon28 is mounted at the distal end of the balloon catheter. Thevalve12 is shown mounted on theballoon28 in a crimped state having a reduced diameter for delivery to the heart via the patient's vasculature.
• Thenose catheter18 includes anelongated shaft30 that extends through theproximal portion24, theshaft26, and theballoon28 of the balloon catheter. Thenose catheter18 further includes anose piece32 mounted at the distal end of theshaft30 and adapted to receive a distal end portion of the balloon when theapparatus10 is used to advance the valve through the patient's vasculature to the implantation site.
• As can be seen inFIGS. 2A and 2B, theballoon catheter16 in the illustrated configuration further includes an inner shaft34 (FIG. 2B) that extends from theproximal portion24 and coaxially through theouter shaft26 and theballoon28. Theballoon28 can be supported on a distal end portion of theinner shaft34 that extends outwardly from theouter shaft26 with aproximal end portion36 of the balloon secured to the distal end of the outer shaft26 (e.g., with a suitable adhesive). The outer diameter of theinner shaft34 is sized such that an annular space is defined between the inner and outer shafts along the entire length of the outer shaft. Theproximal portion24 of the balloon catheter can be formed with afluid passageway38 that is fluidly connectable to a fluid source (e.g., a water source) for inflating the balloon. Thefluid passageway38 is in fluid communication with the annular space between theinner shaft34 and theouter shaft26 such that fluid from the fluid source can flow through thefluid passageway38, through the space between the shafts, and into theballoon28 to inflate the same and deploy thevalve12.
• Theproximal portion24 also defines aninner lumen40 that is in communication with alumen42 of theinner shaft34. Thelumens40,42 in the illustrated embodiment are sized to receive theshaft30 of the nose catheter. Theballoon catheter16 also can include acoupler44 connected to theproximal portion24 and atube46 extending from the coupler. Thetube46 defines an internal passage which fluidly communicates with thelumen40. Theballoon catheter16 also can include aslide support48 connected to the proximal end of thecoupler44. Theslide support48 supports and cooperates with an adjustment ring50 (FIGS.1 and4A-4B) of thenose catheter18 to allow the nose catheter to be maintained at selected longitudinal positions relative to theballoon catheter16, as described in greater detail below.
• As shown inFIG. 2A, the outer surface of theouter shaft26 can include one or more annular grooves ornotches52a,52b,52cspaced apart from each other along the proximal end portion of theshaft26. The grooves cooperate with alocking mechanism84 of the guide catheter14 (FIGS. 3A-3B) to allow theguide catheter14 to be maintained at selected longitudinal positions relative to theballoon catheter16, as described in greater detail below.
• Theinner shaft34 and theouter shaft26 of the balloon catheter can be formed from any of various suitable materials, such as nylon, braided stainless steel wires, or a polyether block amide (commercially available as Pebax®). Theshafts26,34 can have longitudinal sections formed from different materials in order to vary the flexibility of the shafts along their lengths. Theinner shaft34 can have an inner liner or layer formed of Teflon® to minimize sliding friction with thenose catheter shaft30.
• Theguide catheter14 is shown in greater detail inFIGS. 3A and 3B. As discussed above, theguide catheter14 includes ahandle portion20 and an elongated guide tube, or shaft,22 extending distally therefrom. Theguide tube22 defines alumen54 sized to receive theouter shaft26 of the balloon catheter and allow the balloon catheter to slide longitudinally relative to the guide catheter. The distal end portion of theguide tube22 comprises asteerable section56, the curvature of which can be adjusted by the operator to assist in guiding the apparatus through the patient's vasculature, and in particular, the aortic arch.
• The guide catheter desirably includes a cover, or shroud,23 secured to the distal end of theguide tube22. Thecover23 in particular embodiments is sized and shaped to receive thevalve12 crimped around the balloon and to abut against the proximal end surface of thenose piece32, which is adapted to cover a distal end portion of the balloon28 (as shown inFIG. 8A). Thus, when the apparatus is advanced to the deployment site, thevalve12 and theballoon28 can be completely enclosed within thecover23 and thenose piece32.
• As further shown inFIGS. 3A and 3B, thehandle portion20 includes a main body, or housing,58 formed with acentral lumen60 that receives the proximal end portion of theguide tube22. Thehandle portion20 can include aside arm62 defining an internal passage which fluidly communicates with thelumen60. A stopcock63 can be mounted on the upper end of theside arm62.
• Thehandle portion20 is operatively connected to thesteerable section56 and functions as an adjustment to permit operator adjustment of the curvature of thesteerable section56 via manual adjustment of the handle portion. In the illustrated embodiment, for example, thehandle portion20 includes aninner sleeve64 that surrounds a portion of theguide tube22 inside thehandle body58. A threadedslide nut68 is disposed on and slidable relative to thesleeve64. Theslide nut68 is formed with external threads that mate with internal threads of anadjustment knob70.
• As best shown inFIGS. 5A and 5B, theslide nut68 is formed with twoslots76 formed on the inner surface of the nut and extending the length thereof. As best shown inFIGS. 6A and 6B, thesleeve64 is also formed with longitudinally extendingslots78 that are aligned with theslots76 of theslide nut68 when the slide nut is placed on the sleeve. Disposed in eachslot78 is a respective elongated nut guide66a,66b(FIG. 3B), which can be in the form of an elongated rod or pin. The nut guides66a,66bextend radially intorespective slots76 in theslide nut68 to prevent rotation of theslide nut68 relative to thesleeve64. By virtue of this arrangement, rotation of the adjustment knob70 (either clockwise or counterclockwise) causes theslide nut68 to move longitudinally relative to thesleeve64 in the directions indicated by double-headedarrow72.
• One ormore pull wires74 connect theadjustment knob70 to thesteerable section56 to produce movement of the steerable section upon rotation of the adjustment knob. In certain embodiments, the proximal end portion of thepull wire74 can extend into and can be secured to a retaining pin80 (FIG. 3A), such as by crimping thepin80 to the pull wire. Thepin80 is disposed in aslot82 in the slide nut68 (as best shown inFIG. 5A). Thepull wire74 extends frompin80, through aslot98 in the slide nut, aslot100 in thesleeve64, and into and through a pull wire lumen in the shaft22 (FIG. 3A). The distal end portion of thepull wire74 is secured to the distal end portion of thesteerable section56.
• Thepin80, which retains the proximal end of thepull wire74, is captured in theslot82 in theslide nut68. Hence, when theadjustment knob70 is rotated to move theslide nut68 in the proximal direction (toward theproximal portion24 of the balloon catheter), thepull wire74 also is moved in the proximal direction. The pull wire pulls the distal end of thesteerable section56 back toward the handle portion, thereby bending the steerable section and reducing its radius of curvature. The friction between theadjustment knob70 and theslide nut68 is sufficient to hold the pull wire taut, thus preserving the shape of the bend in the steerable section if the operator releases theadjustment knob70. When theadjustment knob70 is rotated in the opposite direction to move theslide nut68 in the distal direction, tension in the pull wire is released. The resiliency of thesteerable section56 causes the steerable to return its normal, non-deflected shape as tension on the pull wire is decreased. Because thepull wire74 is not fixed to theslide nut68, movement of the slide nut in the distal direction does not push on the end of the pull wire, causing it to buckle. Instead, thepin80 is allowed to float withinslot82 of theslide nut68 when theknob70 is adjusted to reduce tension in the pull wire, preventing buckling of the pull wire.
• In particular embodiments, thesteerable section56 in its non-deflected shape is slightly curved and in its fully curved position, the steerable section generally conforms to the shape of the aortic arch. In other embodiments, the steerable section can be substantially straight in its non-deflected position.
• Thehandle portion20 can also include alocking mechanism84 that is configured to retain theballoon catheter16 at selected longitudinal positions relative to theguide catheter14. Thelocking mechanism84 in the illustrated configuration comprises apush button86 having anaperture88 through which theouter shaft26 of the balloon catheter extends. As best shown inFIG. 3A, thebutton86 has adistal end portion90 that is partially received in aninternal slot92. Acoil spring94 disposed in theslot92 bears against and resiliently urges thedistal end portion90 toward theshaft26. Thedistal end portion90 can be formed with asmall projection96 that can nest within any ofgrooves52a,52b,52con the shaft26 (FIG. 2A). When one of the grooves is aligned with theprojection96, thespring94 urges the projection into the groove to retain theshaft26 at that longitudinal position relative to the guide catheter (as depicted inFIG. 3A). Since the grooves in the illustrated embodiment extend circumferentially completely around theshaft26, the balloon catheter can be rotated relative to the guide catheter when the longitudinal position of the balloon catheter is locked in place by thebutton86. The position of the balloon catheter can be released by pressing inwardly on thebutton86 against the bias of thespring94 to remove theprojection96 from the corresponding groove on theshaft26.
• Thehandle portion20 can have other configurations that are adapted to adjust the curvature of thesteerable section56. One such alternative handle configuration is shown co-pending U.S. patent application Ser. No. 11/152,288 (published under Publication No. US2007/0005131), which is incorporated herein by reference. Another embodiment of the handle portion is described below and shown inFIGS. 11-15.
• FIGS. 7A and 7B show theguide catheter shaft22 constructed in accordance with one specific embodiment. Theshaft22 in the illustrated embodiment comprises a tubularinner liner104 made of a low-friction polymeric material, such as PTFE. Theliner104 is sized to allow a deflatedballoon28 and theballoon catheter shaft26 to be inserted therethrough. A smaller conduit, orliner106, which extends along the outside of theinner liner104, defines a lumen through which thepull wire74 extends. Anouter layer108 surrounds theliners104,106 and imparts the desired flexibility and stiffness to theshaft22.
• Theouter layer108 in the illustrated embodiment comprises a braided layer formed from braidedmetal wire110 wound around theliner104 and theconduit106, and apolymeric material112 surrounding and encapsulating the braided metal wire layer. In particular embodiments, the shaft can be formed by forming theliners104,106, placing the liners side-by-side in a parallel relationship relative to each other, wrapping the metal wire around the liners to form the braided layer, placing a polymeric sleeve over the braided layer, and reflowing the sleeve to form auniform laminate layer108 surrounding the liners. In certain embodiments, thepolymeric material112 comprises any suitable material, but desirably comprises a thermoplastic elastomer, such as Pebax®. The braided metal layer can be constructed from stainless steel wire.
• As best shown inFIG. 7A, theshaft22 desirably comprises a relativelystiff section114 extending from theproximal end116 of the shaft to theproximal end118 of thesteerable section56. In particular embodiments, the length of thesteerable section56 comprises about ¼ of the overall length of theshaft22. In a working embodiment, the overall length of theshaft22 is about 45 inches (including the steerable section) and the length of the steerable section is about 11.7 inches, although the overall length of the shaft and/or the length of the steerable section can be varied depending on the particular application.
• Thesteerable section56 of the shaft desirably is formed from a relativelysoft durometer material112 to allow the steerable section to bend upon adjustment of theadjustment knob70, as described above. Thestiff section114 desirably is formed from a relatively stifferpolymeric material112 that resists bending when the pull wire is tensioned by theadjustment knob70. Thestiff section114 desirably exhibits sufficient rigidity to allow the operator to push theapparatus10 through a potentially constricting body vessel. In particular embodiments, thepolymeric material112 of the steerable section comprises 55D Pebax® and thepolymeric material112 of the remainingsection114 of the shaft comprises 72D Pebax®, which is stiffer than 55D Pebax®.
• In alternative embodiments, the metal braided layer in thesteerable section56 can be replaced with a metal coil (e.g., a stainless steel coil) disposed on theinner liner104 to enhance the flexibility of the steerable section. Thus, in this alternative embodiment, the braided metal layer extends along thestiff section114 and the metal coil extends along thesteerable section56. In another embodiment, the metal braided layer in thesteerable section56 can be replaced with a stainless steel hypotube that is formed with laser-cut, circumferentially extending openings, such as disclosed in co-pending U.S. patent application Ser. No. 11/152,288.
• As shown inFIG. 7C, the distal end of theshaft22 can include a flared, or enlarged,end portion116. The outer diameter D of theend portion116 is equal to or about the same as the outer diameter of the crimpedvalve12 supported on theballoon28. Accordingly, when thevalve12 is advanced through an introducer sheath, theend portion116 pushes against the crimpedvalve12, rather than theballoon28. This minimizes inadvertent movement between the balloon catheter and the valve, which can cause the position of the valve on the balloon to move. In particular embodiments, theshaft22 has an outer diameter of about 16 F to about 18 F and theend portion116 has an outer diameter D of about 22 F. Theenlarged end portion116 can be made of any of various suitable materials. For example, theend portion116 can be molded from Pebax® (e.g., 55D Pebax®) and reflowed on the end portion of thesteerable section56.
• As mentioned above, the distal end of thepull wire74 is secured at the distal end of thesteerable section56. As best shown inFIG. 7C, this can be achieved by securing the distal end portion of thepull wire74 to ametal ring118 embedded in theouter layer108 of the shaft, such as by welding the pull wire to the metal ring.
• Although not shown inFIGS. 7A-7C, theguide catheter shaft22 can include acover23 for covering thevalve12 and the balloon28 (or a portion thereof) during delivery of the valve. As explained below, the use of an introducer sheath can be optional if the valve is covered upon insertion into the patient's vasculature.
• Referring toFIGS. 4A and 4B, and as discussed briefly above, thenose catheter18 includes anadjustment ring50 at its proximal end and anose piece32 at its distal end, and anelongated shaft30 extending therebetween. Theshaft30 desirably is formed with alumen120 extending the length of the shaft for receiving a guide wire140 (FIG. 8A) so that theapparatus10 can be advanced over the guide wire after it is inserted into the delivery path in the body. As shown inFIGS. 4A and 4B, thenose piece32 desirably is formed with an opening orcavity122 sized and shaped to receive at least a distal end portion of theballoon28.
• As best shown inFIG. 4A, theadjustment ring50 is disposed on and slidable relative to theslide support48 of the balloon catheter, which function as a locking or retaining mechanism for retaining the nose catheter at selective longitudinal positions relative to the balloon catheter. Explaining further, theshaft30 extends through and is fixedly secured to ashaft support124 disposed within theside support48. Theadjustment ring50 is secured to theshaft support124 byscrews126, which extend throughelongated slots128a,128bin theslide support48.Slots128a,128bextend longitudinally along the length of theslide support48. Hence, when theadjustment ring50 is slid longitudinally along the length of the slide support48 (in the directions indicated by double-headed arrow130), theshaft support124 and theshaft30 are caused to move in the same direction so as to adjust the longitudinal position of the nose catheter relative to the balloon catheter.
• Theslot128ais formed with circumferentially extending notches132a-132dand theslot128bis formed with similar circumferentially extending notches134a-134dopposite the notches132a-132d. Thus, for each notch132a-132d, there is a corresponding, diametrically opposed notch134a-134dextending fromslot128b. To retain the longitudinal position of the nose catheter relative to the balloon catheter, theadjustment ring50 is moved to align thescrews126 with a pair of diametrically opposed notches and then rotated slightly to position thescrews126 in the notches. For example,FIG. 4A shows thescrews126, positioned innotches132band134b. The notches restrict movement of thescrews126, and therefore theshaft support124 and theshaft30, in the distal and proximal directions.
• In the illustrated embodiment, eachslot128a,128bis formed with four notches. When thescrews126 are positioned innotches132c,134cor innotches132d,134d, thenose piece32 is retained at a position covering a distal end portion of theballoon28 and abutting thecover23 of theguide catheter14 such that theballoon28 and thevalve12 are completely enclosed by thecover23 and the nose piece32 (FIG. 8A). When thescrews126 are positioned innotches132b,134b, thenose piece32 is retained at a position spaced distally a first distance from theballoon28 so that the valve can be deployed by inflating the balloon without inference from the nose piece (FIG. 8C). When the screws are positioned innotches132a,134a, the nose piece is retained at a position spaced distally a second distance, greater than the first distance, from theballoon28. In this position, theballoon28 can be refolded inside the cover23 (after valve deployment) without interference from the nose piece.
• Thevalve12 can take a variety of different forms. In particular embodiments, the valve generally comprises an expandable stent portion that supports a valve structure. The stent portion desirably has sufficient radial strength to hold the valve at the treatment site and resist recoil of the stenotic native valve leaflets. Additional details regarding balloon expandable valve embodiments can be found in U.S. Pat. Nos. 6,730,118 and 6,893,460, each entitled IMPLANTABLE PROSTHETIC VALVE, which are incorporated by reference herein. It will also be appreciated that the delivery system may be used with self-expanding prosthetic valves. For example, when using a self-expanding valve, a pusher may be used to assist in ejecting the self-expanding valve from a delivery sleeve that maintains the valve in its compressed state.
• When thevalve12 is used to replace the native aortic valve (or a previously implanted, failing prosthetic aortic valve), thevalve12 can be implanted in a retrograde approach where the valve, mounted on the balloon in a crimped state, is introduced into the body via the femoral artery and advanced through the aortic arch to the heart. In use, a guide wire140 (FIG. 8A) can be used to assist in advancing thedelivery device10 through the patient's vasculature. Theguide wire140 can be placed in the body vessel through a dilator (not shown), which expands the inner diameter of the body vessel for introducing the delivery device. Dilator diameters range between, for example, 12 and 22 French.
• As noted above, and as shown inFIG. 8A, thevalve12 can be positioned inside thecover23 with thenose piece32 covering the distal end portion of theballoon28 and abutting the distal end of thecover23. Theadjustment ring50 of the nose catheter can be locked in place to retainnose piece32 against thecover23 during delivery. In this position, the nose catheter desirably is placed in slight tension with thenose piece32 held tightly against thecover32 to inhibit separation of the nose piece from the cover while tracking the device through the vasculature and during removal of the delivery apparatus from the body.
• Advantageously, because thevalve12 in the illustrated embodiment can be completely covered by thecover23, an introducer sheath is not needed to introduce the valve into the body vessel. An introducer sheath having a diameter of about 22 to 24 French typically is used in a retrograde procedure. In contrast, thecover23 desirably has an outer diameter that is less than the outer diameter of the introducer sheath, and in particular embodiments, the outer diameter of thecover23 is in the range of about 0.260 inch to about 0.360 inch, with about 0.330 inch being a specific example. By reducing the overall diameter of the device, it is less occlusive to the femoral artery and the patient's leg can remain well perfused during the procedure. Further, because thecover23, which represents the largest diameter of the delivery device, need only be in contact with the femoral and iliac arteries for only a very short period of time, trauma to these vessels can be minimized.
• Although less desirable, in other embodiments thecover23 can be shorter in length so that less of the outer surface of the valve and the balloon is covered by thecover23 during delivery. For example, thecover23 can be dimensioned to extend over only a proximal end portion of the balloon or a proximal end portion of the valve.
• As thedelivery apparatus10 is advanced over theguide wire140 and through the aortic arch, theguide catheter14 is used to “steer” the apparatus away from the inner surface of the aorta. The tapered distal end portion of thenose piece32 assists in tracking through the femoral and iliac arteries, as well as provides atraumatic tracking through over the aortic arch and smooth crossing of the native aortic valve. In prior delivery systems, it is known to fix a nose piece at the distal end of the balloon catheter, which increases the length of the portion of the device that cannot be curved by operation of a guide catheter. In contrast, thenose piece32 in the illustrated embodiment is mounted onseparate nose catheter18 that can be moved relative to thevalve12. Thenose piece32 therefore can be mounted over the distal end portion of the balloon during delivery in order to minimize the length of the non-steerable section at the distal end of the delivery device. This allows for easier tracking through the aortic arch with little or no contact between the end of the delivery device and the inner walls of the aorta. In particular embodiments, the length L (FIG. 8A) of the non-steerable section at the end of the delivery device is about 6 cm or less.
• Using conventional fluoroscopy, the operator can track the positions of marker bands142 (FIGS. 2A and 2B) on theguide wire shaft34 in order to position the valve at the implantation site. After thevalve12 is advanced into the aortic annulus, the nose catheter can be moved distally relative to the balloon catheter to advance thenose piece32 distally away from the balloon28 (FIG. 8B) and the guide catheter can be moved proximally relative to the balloon catheter to expose thevalve12 from the cover23 (FIG. 8C). As explained above, the longitudinal positions of the nose catheter and the guide catheter can be fixed relative to the balloon catheter while the operator adjusts the position of and then deploys thevalve12. Inflation of theballoon28 is effective to expand thevalve12 to engage the native valve leaflets. Theballoon28 can then be deflated and retracted back into thecover23 and thenose piece32 can be pulled back over the distal end portion of the balloon. The entire delivery apparatus can then withdrawn back over theguide wire140 and removed from the body, after which the guide wire can be removed from the body.
• FIG. 9 shows an alternative embodiment of thedelivery apparatus10. In this embodiment, theguide catheter14 is not provided with a cover23 (as previously illustrated inFIGS. 3A and 3B) and instead anintroducer sheath150 can be used to introduce the delivery apparatus into the body. As best shown inFIGS. 10A and 10B, theintroducer sheath150 in the illustrated embodiment includes anintroducer housing152 and anintroducer sleeve154 extending from thehousing152. Thehousing152 houses a sealingvalve166. In use, thesleeve154 is inserted into a body vessel (e.g., the femoral artery) while thehousing152 remains outside the body. Thedelivery apparatus10 is inserted through aproximal opening168 in the housing, the sealingvalve166, thesleeve154 and into the body vessel. The sealingvalve166 sealingly engages the outer surface of theguide catheter shaft22 to minimize blood loss. In certain embodiments, thesleeve154 can be coated with a hydrophilic coating and extends into the body vessel about 9 inches, just past the iliac bifurcation and into the abdominal aorta of the patient.
• Thesleeve154 can have a taperedsection156 that tapers from a first diameter at aproximal end158 to a second, smaller diameter at adistal end160. A reduced diameterdistal end portion162 extends from the taperedportion156 to the distal end of thesleeve154. The taperedportion156 provides for a smoother transition between the outer surface of thesleeve154 and the outer surface of theguide shaft22 of theguide catheter14. The taperedportion156 also allows for variable placement of thesleeve154 in the patient's vasculature to help minimize complete occlusion of the femoral artery.
• FIGS. 11-15 show an alternative embodiment of a handle portion, indicated at200, that can be used in the guide catheter14 (FIGS. 1 and 3A), in lieu ofhandle portion20. Thehandle portion200 in the illustrated embodiment includes amain housing202 and anadjustment lever204 pivotably connected to thehousing202. Thelever204 can be pivoted distally and proximally (as indicated by double-headedarrow206 inFIG. 13) to adjust the curvature of theshaft22, as further described below.
• As best shown inFIG. 14, thehousing202 can be formed from first andsecond housing portions208,210 that can be secured to each other using a suitable adhesive, mechanical fasteners, a snap fit connection, or other suitable techniques. Disposed within thehousing202 is aseal housing212 that has acentral bore226 extending therethrough. The distal end portion of thebore226 can form an enlarged portion that receives theproximal end portion214 of theshaft22. Theshaft22 extends from theseal housing212 through themain housing202 and out of anose piece228 connected to the distal end of themain body202. Anend piece216 can be connected to the proximal end of theseal housing212 with aseal218 captured between these two components. As best shown inFIG. 15, theend piece216 can be formed with a stepped bore shaped to receive theseal218 and an end portion of theseal housing212. Theseal218 can be made of a suitable elastomer, such as silicon. Theshaft26 of theballoon catheter16 extends through theend piece216, a central opening in theseal218, theseal housing212, and theguide catheter shaft22. Theseal housing212 can be formed with aflush port220 that is in fluid communication with thecentral bore226. Theflush port220 receives one end of aflexible tube222. The opposite end of thetube222 can be connected to a stopcock224 (FIG. 11).
• As shown inFIG. 14, thelever204 in the illustrated configuration comprises first andsecond lever portions230,232, respectively, mounted on opposite sides of themain housing202. The inner surface of each lever portion can be formed with anannular groove274 adapted to receive a respective O-ring234. Thelever portion230 can be coupled to apulley236 mounted in the housing to produce rotation of the pulley upon pivoting movement of the lever portion. For example, thelever portion230 can be formed with aprojection238 that extends through thehousing portion208 and into a complementary shaped recess240 (FIG. 16A) in thepulley236. Theprojection236 can be formed with flats on its outer surface that engage corresponding flats in therecess240 to produce rotation of the pulley when the lever is activated. Thepulley236 can also be formed with a non-circular recess or opening242 that is shaped to receive one end portion of a shaft244 (FIG. 14). The opposite end of theshaft244 extends through thesecond housing portion210 and into a complementary shaped recess or opening246 of the lever portion232 (FIG. 17). In the illustrated configuration, the end portions of theshaft244 and the correspondingopenings242 and246 are hexagonal to inhibit relative rotation between theshaft244, thepulley236, and thelever portion232, although various other non-circular shapes can be used. Alternatively, the end portions of the shaft and theopenings242,246 can be circular if the shaft is otherwise fixed against rotation relative to the pulley and the lever portion.
• Upper andlower cross-bars248,250, respectively, are connected to and extend between respective upper and lower ears of the first andsecond lever portions230,232.Screws252 extending through the ears of thelever portions230,232 and tightened into thecross-bars248,250 can be used to secure the components of thelever204 to themain body202. Ascrew254 can extend through thelever portion230, thehousing portion208, and into a threaded opening in theshaft244. Anadjustment knob266 can be fixedly secured to ascrew268, which can extend through thelever portion232, thehousing portion210, and into a threaded opening in the opposite end of theshaft244. Thescrew268 can be fixedly secured to the adjustment knob, for example, by adhesively securing the head of the screw within a recess (not shown) on the inner surface of the adjustment knob. Consequently, theadjustment knob266 can be manually rotated to loosen or tighten the screw into theshaft244 to adjust the rotational friction of thepulley236.
• Referring again toFIG. 15, apull wire74 extends through a pull wire lumen in theshaft22 and extends from the shaft inside of themain housing202. Aflexible tension member256, such as a piece of string, is tied off or otherwise connected to at one thereof to the end of thepull wire74. Thetension member256 extends around across-member258, partially around the outer circumference of thepulley236, through aradially extending opening260 in the pulley and is tied off or otherwise connected to theshaft244 adjacent the center of thepulley236. As shown inFIGS. 16A and 16B, thepulley236 can be formed with an annular groove orrecess262 adapted to receive thetension member256.
• Explaining the operation of thehandle portion200,FIG. 18A shows theadjustment lever204 in a forward-most position. In this position, thesteerable section56 of theshaft22 is in its normal, non-deflected state (e.g., straight, such as shown inFIG. 1, or slightly curved). As thelever204 is pivoted rearwardly, in the direction ofarrow264, thepulley236 is rotated clockwise in the illustrated embodiment, causing the tension member to wind around the pulley and pull thepull wire74 rearwardly. Thepull wire74, in turn, pulls on the distal end of the shaft to adjust the curvature of thesteerable section56, in the manner previously described.FIG. 18B shows thelever204 in a rearward-most position corresponding to the fully curved position of the steerable section of theshaft22.
• The rotational friction of thepulley236 is sufficient to hold the pull wire taut, thus preserving the shape of the bend in the steerable section if the operator releases theadjustment lever204. When thelever204 is pivoted back toward the forward-most position (FIG. 18A), tension in the pull wire is released. The resiliency of thesteerable section56 causes the steerable section to return to its normal, non-deflected shape as tension on the pull wire is released. Because thetension member256 in the illustrated embodiment does not apply a pushing force to the pull wire, movement of thelever204 toward the forward-most position does not cause buckling of the pull wire. Further, as noted above, theadjustment knob266 can be adjusted by the operator to vary the rotational friction of thepulley236. The rotational friction desirably is adjusted such that if the guide catheter is pulled back inadvertently while in the patient's vasculature, the pulley can rotate toward the forward-most position under a forward pulling force of the pull wire (as indicated byarrow270 inFIG. 18B) to allow the steerable section to straighten out as it is pulled through the vasculature, minimizing trauma to the vasculature walls.
• Advantageously, theadjustment lever204 in the illustrated embodiment provides a substantially 1:1 deflection of the steerable section in response to movement of the lever; that is, rotation of thelever204 causes a substantially 1:1 movement of the pull wire and therefore thesteerable section56. In this manner, theadjustment lever204 provides the operator tactile feedback of the curvature of the steerable section to facilitate tracking through the vasculature. In addition, the lever is ergonomically positioned for maintaining the proper orientation of the guide catheter during use. Another advantage of the illustratedhandle portion200 is that theproximal portion24 of the balloon catheter16 (FIG. 2B) or a portion thereof can seat within theend piece216 to minimize the working length of the balloon catheter.
• FIGS. 19A and 19B illustrate analternative nose catheter300, according to one embodiment, that can used with the delivery apparatus10 (FIG. 1), in lieu of thenose catheter18. Thenose catheter300 in the illustrated configuration includes a nose piece orvalve cover302 connected to anose catheter shaft304. Thevalve cover302 is adapted to cover theballoon28 and avalve12 mounted on the balloon. Thus, in this embodiment, theguide catheter14 need not have a cover23 (FIG. 8A) to cover the valve during delivery. Theshaft304 is fixedly secured at its distal end to the distal end of thecover302 and extends through theballoon28 and theballoon catheter shaft26. Theshaft304 can have a lumen to receive aguide wire140. Theshaft304 can move longitudinally relative to the balloon catheter and the guide catheter, much like thenose catheter18 previously described.
• As best shown inFIG. 19A, thecover302 has aproximal end portion306 formed with a plurality of slits definingtriangular flaps308. Theflaps308 can flex radially outwardly from each other to form an opening large enough to allow passage of theballoon28 and thevalve12 when it is desired to deploy the valve. Theproximal end portion306 can be tapered as shown to facilitate retraction of thecover302 back into an introducer sheath. The tapered shape of theend portion306 also provides an atraumatic surface to minimize trauma to the vasculature walls when the delivery apparatus is withdrawn from the body. The cover also can have a tapereddistal end portion310 to assist in tracking through the femoral and iliac arteries, as well as provide atraumatic tracking through the aortic arch and smooth crossing of the native aortic valve.
• Thecover302 desirably is made from a flexible material, such as nylon, Pebax®, or PET and can have a wall thickness in the range of about 0.0015 inch to about 0.015 inch. By making thecover302 sufficiently flexible, the only relatively stiff, non-flexible section along the portion of the delivery apparatus advanced through the patient's vasculature is the section of the balloon covered by the valve. This greatly enhances the ability of the delivery apparatus to follow the path of theguide wire140 as it is advanced through tortuous body vessels.
• In use, the delivery apparatus is advanced over theguide wire140 until the valve is positioned at or near the deployment location. Thenose catheter300 is then advanced distally relative to theballoon catheter16 to uncover the balloon and thevalve12, as illustrated inFIG. 19C. As thecover302 is advanced distally, the balloon and the valve can pass through the proximal opening formed byflaps308. Once thevalve12 is exposed, theballoon28 can be inflated to deploy the valve.
• FIG. 20A shows a modification of theguide catheter14 where thevalve cover23 is replaced with an expandable mesh basket or cover400 connected to the distal end of theguide catheter shaft22. Thecover400 is sized and shaped to cover thevalve12 and theballoon28. Thus, in this embodiment, a nose catheter (e.g., nose catheter18) need not be used. Thecover400 can have a braided mesh construction foamed from metal wire (e.g., Nitinol or stainless steel wires).
• One ormore ribbon wires402 are connected to thedistal end404 of thecover400 and extend through respective lumens in theguide catheter shaft22 along the length thereof.
• (FIG. 20B). Thewires402 can be, for example, 0.003 inch×0.020 inch Nitinol ribbon wire. Thewires402 are connected at their proximal ends to a handle portion of the guide catheter that allows the operator to apply pushing or pulling forces to the wires. Pushing thewires402 forward, in the direction ofarrow406, causes the cover to collapse over theballoon28 and thevalve12 to provide a smooth tracking profile. Pulling thewires402 rearward, in the direction ofarrow408, causes the cover to expand and allows the balloon and valve to be advanced outwardly through an opening at thedistal end404 of thecover400.
• In use, thecover400 is placed in a collapsed state covering the valve and the balloon for delivery through the patient's vasculature to the deployment site. Thewires402 are then pulled in the proximal direction (as indicted by arrow408) to expand thecover400. The guide catheter can then be pulled in the proximal direction to advance the balloon and the valve from the distal end of the cover. Alternatively, theballoon catheter16 can be advanced distally relative to theguide catheter14 to advance the balloon and the valve from thecover400.
• FIGS. 21A-21C show an alternative embodiment of a delivery apparatus, indicated at500. Thedelivery apparatus500 allows avalve12 to be mounted on aballoon28 of a balloon catheter inside a body vessel. The balloon catheter can have a construction similar to the balloon catheter shown inFIGS. 2A and 2B except that in the embodiment ofFIGS. 21A-21B, theballoon catheter shaft26 has adistal end portion504 that extends distally from theballoon28 and an annulartapered wedge502 is disposed on thedistal end portion504 adjacent the balloon. The taperedwedge502 functions to expand the valve to facilitate positioning the same on the balloon inside the body, as further described below. Thewedge502 desirably is made from a low-friction material, such as nylon, to allow the valve to easily slide over the wedge and onto the balloon.
• The delivery apparatus includes a nose catheter comprising ashaft506 and anose piece508 connected to the distal end of theshaft506. Thenose catheter shaft506 can have a guide wire lumen to receive aguide wire140 so that the apparatus can be advanced over the guide wire with the guide wire passing through the lumen. Thedelivery apparatus500 can further include a guide catheter comprising aguide catheter shaft22 and anelongated cover510 extending from the distal end of theshaft22. The nose catheter, balloon catheter, and guide catheter are moveable longitudinally relative to each other and can have locking mechanisms at the proximal end of the apparatus for retaining the catheters at selected longitudinal positions relative to each other, as described in detail above.
• As shown inFIG. 21A, thevalve12 is initially mounted in a crimped state on thenose catheter shaft506 between thenose piece508 and the taperedwedge502, rather than on the balloon prior to inserting the delivery apparatus into the body. The valve is crimped onto the nose catheter shaft such that that valve can still move along the shaft when it is desired to place the valve on theballoon28. Thenose piece508 can be formed with a stepped bore comprising afirst bore portion512 and a second,enlarged bore portion514 at the proximal end of the nose piece. The stepped bore can be formed with anannular shoulder516 extending between the first and second bore portions and adapted to engage the distal end of thevalve12 when the valve is inserted into thesecond portion514. Thenose piece508 can have an outer surface that tapers in a direction toward the distal end of thenose piece508 to provide atraumatic tracking through tortuous vasculature. Thecover510, which can be optional, is adapted to extend over and cover theballoon28, thewedge502, and at least a proximal end portion of thevalve12 when the valve is positioned on the nose catheter shaft for delivery. In the illustrated embodiment, the distal end of thecover510 can be positioned to abut the proximal end of thenose piece508 so as to completely enclose the valve during delivery. In alternative embodiments, thecover510 can be shorter in length so that less of the outer surface of the valve or the balloon is covered during delivery.
• Thenose piece508, when moved proximally relative to the balloon catheter (in the direction indicated by arrow518), pushes thevalve12 over thewedge502 and onto theballoon28. As the valve passes over the wedge, the valve expands slightly to facilitate positioning the same on the balloon. Theballoon catheter shaft26 can have radiopaque markers520 (FIG. 21A) to assist the operator in aligning the valve at the proper location on the balloon. The nose piece can have anouter layer522 formed from a relatively soft and flexible material and aninner layer524 formed from a relatively harder material. Theinner layer524 in the illustrated embodiment forms theshoulder516 and the inner surface of thefirst bore portion512. In this manner, the nose piece exhibits sufficient rigidity to push thevalve12 over the wedge and onto the balloon and provides a soft outer surface to minimize trauma to the body vessels. For example, theouter layer522 can be made of 55D Pebax® and the inner layer can be made of 72D Pebax®, which is stiffer than 55D Pebax®.
• The section of the delivery apparatus mounting the valve typically defines the maximum outer diameter of the apparatus inserted into the body. By mounting thevalve12 on the nose catheter shaft rather than on the balloon prior to insertion into the body, thevalve12 can be crimped to a smaller diameter than if the valve is mounted on the balloon. Accordingly, the maximum outer diameter of the delivery apparatus can be reduced for insertion into and through the vasculature. As noted above, by reducing the maximum diameter of the delivery apparatus, it is less occlusive to the femoral artery and therefore the patient's leg can remain well perfused during the procedure. In certain embodiments, the maximum outer diameter of thecover510 and the nose piece508 (at its proximal end) is about 0.223 inch, which is the maximum diameter of the portion of the delivery apparatus that is inserted into the body. Thewedge502 can have a diameter at its proximal end of about 0.120 inch and theguide catheter shaft22 can have an outer diameter of about 0.184 inch.
• Explaining now the operation of thedelivery apparatus500, according to one embodiment, thevalve12 is initially mounted on the nose catheter shaft and inserted into thenose piece508 and thecover510. After aguide wire140 is inserted into the body, the proximal end of the wire extending from the body can be inserted into the distal end of the guide wire lumen and thedelivery apparatus500 can be inserted into a body vessel (e.g., the femoral artery) and advanced through the body (as depicted inFIG. 21A). Alternatively, an introducer sheath can be inserted first into the body vessel, for example if acover510 is not provided to cover thevalve12. Subsequent to inserting the introducer sheath, the delivery apparatus can be inserted through the introducer sheath and into the body vessel.
• When the distal end of the delivery apparatus is advanced to a location that is convenient to slide thevalve12 onto the balloon, the guide catheter is retracted proximally relative to the balloon catheter to advance the valve and the balloon from thecover510. For example, if implanting a prosthetic valve within the native aortic valve, the valve and the balloon can be advanced into the ascending aorta or into the left ventricle where the valve can then be moved onto the balloon. In any case, as shown inFIG. 21B, the nose catheter can be retracted proximally to advance the valve over thewedge502 and onto theballoon28. Markers520 (FIG. 21A) can be used to center the valve on the balloon. After mounting the valve on the balloon, the nose catheter can be advanced distally so as not to interfere with inflation of the balloon, as shown inFIG. 21C. The valve can then be positioned at the implantation site (e.g., within the native aortic valve) and deployed by inflating the balloon.
• FIGS. 22A and 22B show a modification of the delivery apparatus10 (FIGS. 1-8). In the embodiment ofFIGS. 22A and 22B, thecover23 has a generally tubular shape but is provided in a rolled up state on the distal end portion of theguide catheter shaft22. After thevalve12 is mounted on theballoon28, the cover can be unrolled over thevalve12 for insertion into and through the patient's vasculature. The operation of the deliver apparatus shown inFIGS. 22A and 22B is otherwise identical to the operation of thedelivery apparatus10 described above with reference toFIGS. 8A-8C.
• FIGS. 23A and 23B show an embodiment of an improved introducer sheath, indicated at600, that can be used to facilitate insertion of a delivery apparatus into a body vessel. Theintroducer sheath600 is particularly suited for use with a delivery apparatus that is used to implant a prosthetic valve, such as the embodiments of delivery apparatus described herein. Theintroducer sheath600 also can be used to introduce other types of delivery apparatus for placing various types of intraluminal devices (e.g., stents, stented grafts, etc.) into many types of vascular and non-vascular body lumens (e.g., veins, arteries, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts, etc.). The example illustrated inFIG. 23A shows the distal end portion of a delivery apparatus used to implant aprosthetic valve12. The delivery apparatus comprises a balloon catheter and a guide catheter. The balloon catheter comprises ashaft26 and aballoon28 mounted on the distal end portion of the shaft. The guide catheter comprises ashaft22 extending over theballoon catheter shaft26. The remaining portions of the balloon catheter and the guide catheter can be constructed according to the embodiment shown inFIGS. 1-8.
• A conventional introducer sheath typically requires a tubular loader to be inserted through the seals in the sheath housing to provide an unobstructed path for a valve mounted on a balloon catheter. The loader extends from the proximal end of the introducer sheath, thereby increasing its working length, and decreasing the available working length of a delivery apparatus that can be inserted into the body. Theintroducer sheath600 includes a integrated loader tube housed in the sheath housing to reduce the working length of the sheath, and therefore increase the available working length of a delivery apparatus that can be inserted into the body.
• For example, the illustratedsheath600 includes aseal housing602 and atubular sleeve604 extending distally from the housing. Theseal housing602 houses one or more sealing valves, such as across-slit valve606, adisc valve608, and ahemostatic valve610 as shown in the illustrated embodiment. The valves desirably are fabricated from a resilient biocompatible material, such as polyisoprene, although similar biocompatible materials also can be used. Thevalves606,608,610 are further shown and described in U.S. Pat. No. 6,379,372, which is incorporated herein by reference. Aspacer612 can be interposed between thedisc valve608 and thecross-slit valve606.
• Coupled to the proximal end of the seal housing is anend piece614 adapted to move longitudinally along the length of the seal housing. In the illustrated embodiment, the end piece has a tubular body formed withinternal threads616 that engageexternal threads618 formed on the outer surface of theseal housing602. Thus, rotation of theend piece614 moves the same inwardly and outwardly relative to the seal housing. Theend piece614 has acentral opening620 and anelongated loader tube622 fixedly secured to the proximal end portion of the end piece and extending distally therefrom. Theopening620 and theloader tube622 are dimensioned to permit passage of the valve12 (or other prosthesis) mounted on the delivery apparatus. Theend piece614 also houses aseal624 having a central opening aligned with theopening620. Theseal624 sealingly engages the outer surface of the delivery apparatus when it is inserted into theintroducer sheath600.
• As noted above, theend piece614 can be adjusted inwardly and outwardly relative to theseal housing602. Adjusting theend piece614 from the extended position shown inFIG. 23A to the retracted position shown inFIG. 23B moves theloader tube622 through theseals606,608,610 to provide an unobstructed path for thevalve12 to pass through the introducer sheath. Because the loader tube does not extend behind the end piece, as in a conventional introducer sheath, the loader tube does not decrease the available working length of the delivery apparatus that can be inserted into the vasculature.
• In use, theintroducer sheath600 in the extended position shown inFIG. 23A can be placed on a previously insertedguide wire140 and advanced thereon until thesleeve604 extends into a body vessel a desired distance. The delivery apparatus can then be inserted through theopening620 to position thevalve12 in theloader tube622 with theseal624 forming a fluid tight seal around theguide catheter shaft22. Subsequently, theend piece614 is rotated to slide theloader tube622 through thevalves606,608,610 (FIG. 23B), thus placing the delivery apparatus in communication with the lumen of thesleeve604 and the body vessel in which the sleeve is inserted. Advantageously, this approach simplifies the loading process and reduces the number of steps and parts required to load the valve into the sheath.
• In an alternative embodiment of theintroducer sheath600, theseal housing602 can have internal threads that engage external threads on theend piece614. The end piece can be rotated to adjust the position of theloader tube622 as previously described. In addition, the pitch of the threads on the seal housing and the end piece can be varied to vary the amount of rotational movement required to extend the loader through the sealing valves. In another embodiment, theend piece614 can be slidingly positionable along the length of the seal housing by pushing and pulling the end piece without rotating the same.
• FIGS. 24A and 24B show another embodiment of a nose catheter, indicated at700, that can be used in the delivery apparatus10 (FIG. 1). Thenose catheter700 includes anose piece702 and anose catheter shaft704. Thenose piece702 has adistal end706 connected to thenose catheter shaft704 and a proximal end connected to the distal end of aballoon catheter shaft26. Thenose piece702 comprises a balloon or similar structure formed from a thin, flexible material, such as nylon or PET, capable of assuming an inverted shape covering avalve12 and aballoon28 or portions thereof when thenose piece702 is urged against theballoon28. For example, thenose piece702 can have a structure similar to theballoon28.
• Thenose catheter shaft704 is slidable relative to theballoon catheter shaft26, although the proximal end of thenose piece702 is connected to the balloon catheter shaft. Hence, as thenose catheter shaft704 is moved proximally relative to the balloon catheter shaft26 (in the direction of arrow710) from a first, extended position (FIG. 24B) toward a second, retracted position (FIG. 24A), thenose piece702 is urged against the distal end of theballoon catheter shaft26, causing thenose piece702 to assume an inverted position covering a portion of the outer surface of theballoon28 and thevalve12. Similarly, it can be seen that moving the balloon catheter shaft distally relative to the nose catheter shaft from the extended position shown inFIG. 24B also is effective to cause the nose piece to assume an inverted position over the balloon and the valve.
• In use, thenose piece702 is initially placed in the inverted position shown inFIG. 24A to provide a smooth tracking profile during delivery of the valve through the patient's vasculature. At or near the implantation site, thenose catheter shaft704 is moved distally relative to the balloon catheter shaft20 (in the direction of arrow712) to uncover thevalve12 and theballoon28 for subsequent deployment of the valve. Desirably, although not necessarily, thenose piece702 can be partially inflated so that it can more readily assume the inverted position shown inFIG. 24A. In this regard, the lumen of thenose catheter shaft704 can be fluidly connected to a fluid source for partially inflating thenose piece702, similar to the way the balloon catheter shaft is used to deliver a fluid to theballoon28.
• FIG. 25A shows the distal end portion of a modification of thedelivery apparatus10. The delivery apparatus in this embodiment includes a steppedballoon800 mounted on the distal end portion of theballoon catheter shaft26 andinner shaft34. As shown inFIG. 25B, the illustratedballoon800 includes a firstslender portion802, a firstconical portion804, a maincylindrical portion806, a secondconical portion808, a secondcylindrical portion810, a thirdconical portion812, and a secondslender portion814. A valve12 (FIG. 25A) can be mounted in a crimped state on the maincylindrical portion806. The steppedballoon800 is further described in detail in co-pending U.S. application Ser. No. 11/252,657 (the '657 application) (published as U.S. Patent Application Publication No. 2007/0088431), which is incorporated herein by reference.
• As shown inFIG. 25A, the delivery apparatus includes a guide catheter comprising aguide catheter shaft22 having anenlarged end portion816 that abuts the proximal end of thevalve12. The guide catheter further includes aretractable cover818 that extends over and covers thevalve12. Thecover818 is operable to slide longitudinally relative to the valve and the distal end of theguide catheter shaft22 to uncover the valve for deployment inside a body vessel.Portions802,804 of theballoon800 extend from the distal end of thecover818 and can be partially inflated to provide a transition member between the distal end of the balloon catheter and thecover818, thereby facilitating tracking through the patient's vasculature, much like nose piece32 (FIG. 1). The end of the balloon extending from thecover818 also can be used as a dilator to dilate stenotic leaflets of a native heart valve or other portions of the patient's vasculature prior to deploying the valve at the desired implantation site, as further described in the '657 application.
• As further shown inFIG. 25A, thecover818 in the illustrated embodiment has a cylindricaldistal end portion820 that extends over thevalve12 and a plurality of circumferentially spacedfingers822 extending proximally from the proximal end of the cylindricaldistal end portion820. The proximal end portion of eachfinger822 is connected to apull wire826 that extends through a respective lumen in theguide catheter shaft22. As shown inFIG. 25C, eachpull wire826 extends distally from arespective lumen828, through anopening830 in theproximal end portion824 of arespective finger822, and back into thelumen828. The guide catheter can further include a flexibleouter cover838 extending over the portions of thepull wires826 extending from theshaft22 to prevent the wires from contacting the inner walls of the vasculature. Thecover838 can be fixedly secured to the outer surface of theshaft22, such as with a suitable adhesive. Alternatively, thecover838 can be adapted to slide longitudinally relative to theshaft22.
• Thecover818 in the illustrated example has fourfingers822, each of which is connected to apull wire826 that extends through arespective lumen828. As shown inFIG. 25D, thelumens828 can be equally spaced around acentral lumen54 of theshaft22. Theshaft22 also can include another lumen for receiving apull wire74 for adjusting the curvature of the guide catheter, as described above. Thepull wires826 extend the length of theguide catheter shaft22 and are operatively connected to an adjustment mechanism at the proximal end of the shaft to permit manual adjustment of thepull wires826, and therefore thecover818.
• FIG. 25E is a schematic illustration of ahandle portion832 connected to the proximal end of the guide catheter shaft. Thehandle portion832 can have a construction similar to the handle portion20 (described above and shown inFIGS. 3A-3B) except that the former can include anadditional adjustment mechanism834 connected to thepull wires826. Theadjustment mechanism834 can be moved fore and aft (in the directions of double-headed arrow836) by the operator to move thepull wires826. Thepull wires826 desirably exhibit sufficient rigidity to apply a pushing force to thecover818 in the distal direction without buckling. The pull wires can be, for example, 0.006 inch×0.012 inch Nitinol ribbon wire. In this manner, thecover818 can be retracted in the proximal direction relative to the valve, and if necessary, moved in the distal direction, such as to retrieve the valve back into thecover818, by operation of theadjustment mechanism834. Further details of an adjustment mechanism that can be used to produce movement of the pull wires in the distal and proximal directions is described in detail in the '657 application.
• When the valve is advanced to the implantation site inside the body, thecover818 is retracted by operation of the adjustment mechanism to uncover the valve. As thecover818 is retracted (relative to theshaft22 and the outer cover838), the distal end of theshaft end portion816 abuts against the valve to prevent inadvertent movement of valve's position on theballoon800. Thereafter, the balloon catheter can be advanced distally relative to the guide catheter to advance the balloon800 a sufficient distance from thecover838 and theshaft end portion816 to permit full inflation of the balloon for deploying thevalve12. Thevalve12 can be a balloon-expandable valve that is deployed by the balloon, or alternatively, thevalve12 can be a self-expanding valve that radially expands when advanced from thecover818. In the latter case, theballoon800 can be used to further expand the valve to ensure tight engagement with the orifice of the native valve.
• In an alternative embodiment, the shaftdistal end portion816 can be configured to provide a releasable attachment to thevalve12, such as described in detail in the '657 application. In this manner, the guide catheter can be moved fore and aft to adjust the position of the valve in the body vessel as the valve is being deployed. Prior to deployment (or after partial deployment, or expansion, of the valve), control of valve positioning can be achieved by the operator pushing, pulling, or twisting the guide catheter. Once the operator is satisfied with the position of the valve, the valve can be fully deployed and the valve is detached from the distal end of the guide catheter shaft.
• FIGS. 25A-25E illustrate another embodiment of an introducer sheath, indicated at900, that can be used to facilitate the introduction of a delivery apparatus into a blood vessel. Theintroducer sheath900 has an expandable,elongated sleeve902 that can be radially expanded from a first diameter (FIG. 25A) to a second, larger diameter (FIG. 25B) to facilitate insertion of the largest portion the delivery apparatus (the portion on which the valve or other prosthetic device is mounted). Thesheath900 further includes ahandle portion904 connected to the proximal end of thesleeve902. Thesleeve902 includes aninner layer906 and anouter layer908. Theinner layer906 can be a braided polymeric layer made from a suitable material such as, peek, nylon, or polypropylene. Theouter layer908 can be formed from urethane or another suitable material. The outer surface of theouter layer908 can be provided with a hydrophilic coating. Thehandle portion904 can house one or more sealing valves configured to sealingly engage the outer surface of a delivery apparatus inserted through the sheath, as previously described.
• As shown inFIG. 25C, thesleeve902 can be formed with a main lumen910 sized to permit passage of a delivery apparatus and one or moreinner conduits912 defining side lumens spaced around the main lumen910. Extending through each side lumen is arespective pull wire914. The proximal end of eachpull wire914 is connected to anadjustment mechanism916 on thehandle portion904. The distal end of eachpull wire914 is fixedly secured to the distal end portion of thesleeve902. For example, as shown inFIG. 25D, eachpull wire914 can extend outwardly from the distal end of a respective lumen and can be welded to theinner layer906 adjacent the distal end of the sleeve.
• Theadjustment mechanism916 is configured to permit manual adjustment of the diameter of thesleeve902 between a first diameter (FIG. 25A) and a second, larger diameter (FIG. 25B). In the illustrated embodiment, for example, the adjustment mechanism can move longitudinally relative to thehandle portion904, in the directions indicated by double-headedarrow918. Moving the adjustment mechanism in the proximal direction (away from the sleeve902) is effective to pull thepull wires914 in the same direction, which causes thesleeve902 to radially expand and to shorten in length. Moving theadjustment mechanism914 in the distal direction (toward the sleeve) releases tension on thepull wires914 to permit thesleeve902 to radially contract and elongate under its own resiliency. In particular embodiments, thesleeve902 has an outer diameter of about 18 F in its contracted state and can expand to an outer diameter of about 28 F.
• In use, thesleeve902 can be inserted into a blood vessel as previously described. As a delivery apparatus (e.g., delivery apparatus10) is inserted through thesleeve902, thesleeve902 can be radially expanded to allow a prosthetic valve (e.g., valve12) or other prosthetic device mounted on the delivery apparatus to easily pass through thesleeve902. Once the prosthetic valve is inserted into the blood vessel, thesleeve902 can be reduced in diameter to minimize occlusion of the vessel.
• In an alternative embodiment, as depicted inFIG. 25E, theinner layer906 can be a laser cut tube rather than a braided layer. The tube can be formed with a plurality of longitudinally extending cuts orslits920 that allow the tube to radially expand and contract.
• The various embodiments of the delivery apparatus disclosed herein can be used for implanting prosthetic devices other than prosthetic heart valves into the body. For example, the delivery apparatus can be used to deliver and deploy various types of intraluminal devices (e.g., stents, stented grafts, etc.) into many types of vascular and non-vascular body lumens (e.g., veins, arteries, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts, etc.). In one specific example, the delivery apparatus can be used to implant a balloon-expandable stent into a coronary artery (or other blood vessels) to maintain the patency of the vessel lumen.
• In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.

Claims (20)

We claim:

1. A system for delivering a radially-compressible-and-expandable prosthetic heart valve through the vasculature of a patient, the system comprising a delivery device, the delivery device comprising:

a proximal end and a distal end;

a handle disposed at the proximal end;

an elongate first shaft comprising a proximal end and a distal end, the proximal end of the first shaft coupled to the handle;

a tubular cover comprising a proximal end and a distal end, the proximal end of the cover coupled to the distal end of the elongate first shaft, the cover sized to receive therein a prosthetic heart valve in a radially compressed configuration, a diameter of the cover greater than a diameter of the first shaft;

an elongate second shaft slideably disposed within the first shaft, a proximal end of the second shaft extending out of a proximal end of the handle, a distal end of the second shaft extending out of the distal end of the first shaft, a distal end portion of the second shaft configured to carry the prosthetic valve in the radially compressed configuration; and

a nose piece comprising a proximal end and a distal end, the nose piece disposed at the distal end of the apparatus,

wherein the delivery device has

a first state in which the first shaft is advanced relative to the second shaft such that the proximal end of the nose piece abuts the distal end of the cover, the nose piece and cover configured to completely enclose the prosthetic valve in the radially compressed configuration therein, and

a second state in which the first shaft is retracted relative to the second shaft, retracting the cover from the nose piece sufficiently to expose the prosthetic valve in the radially compressed configuration; and

wherein the system does not require a separate introducer sheath.

2. The system ofclaim 1, wherein the delivery device further comprises a guide wire lumen extending longitudinally therethrough, the system further comprising a guide wire.

3. The system ofclaim 1, wherein a maximum diameter of the cover and the nose piece is the maximum diameter of any portion of the delivery device configured for insertion into a patient.

4. The system ofclaim 1, wherein the cover is sized to completely enclose a prosthetic valve in a radially compressed configuration.

5. The system ofclaim 1, wherein an outer diameter of the cover is from about 0.260 inch to about 0.360 inch.

6. The system ofclaim 1, wherein an outer diameter of the cover is about 0.223 inch.

7. The system ofclaim 1, wherein the first shaft is a guide catheter, a distal end portion of the first shaft comprising a steerable section, wherein the delivery device further comprises a pull wire and an actuator, the actuator disposed on the handle, a first end of the pull wire coupled to the steerable section of the first catheter and a second end of the pull wire coupled to the actuator.

8. The system ofclaim 1, wherein the handle comprises a locking mechanism configured for maintaining at least one relative longitudinal position between the first shaft and the second shaft.

9. The system ofclaim 1, wherein the delivery device further comprises an elongate nose catheter extending through the second shaft, the nose piece disposed on a distal end of the nose catheter.

10. The system ofclaim 1, further comprising a prosthetic valve, the prosthetic valve comprising a radially compressible and expandable stent portion supporting a valve structure.

11. The system ofclaim 10, wherein the prosthetic valve is a prosthetic aortic valve.

12. The system ofclaim 10, wherein the prosthetic valve is self-expanding.

13. The system ofclaim 12, wherein the second shaft is a pusher.

14. A method for implanting a prosthetic valve in a patient in need thereof, the method comprising:

inserting into a vasculature of a patient a prosthetic valve in a radially compressed state, the prosthetic heart valve disposed at a distal end portion of an elongate delivery device, a nose piece and a cover of the delivery device completely enclosing the prosthetic heart valve;

advancing the prosthetic valve through the vasculature to an implantation site;

retracting the cover relative to the nose piece, thereby exposing the prosthetic valve;

expanding the prosthetic valve at the implantation site, thereby implanting the prosthetic valve; and

removing the delivery device from the vasculature of the patient,

wherein the prosthetic valve is inserted into the vasculature without using a separate introducer sheath.

15. The method ofclaim 14, wherein advancing the prosthetic valve through the vasculature comprising advancing the prosthetic valve to a native aortic valve.

16. The method ofclaim 14, wherein advancing the prosthetic valve through the vasculature comprises advancing the prosthetic valve over a guide wire.

17. The method ofclaim 14, wherein expanding the prosthetic valve comprises allowing the prosthetic valve to self expand.

18. The method ofclaim 14, wherein expanding the prosthetic valve comprises balloon expanding the prosthetic valve.

19. The method ofclaim 14, wherein a maximum diameter of the cover and the nose piece is the maximum diameter of a portion of the delivery device that is inserted into the patient.

20. The method ofclaim 14, further comprising retrieving the prosthetic valve back into the cover.

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