Distal Tip Assembly for a Heart Valve Delivery Catheter

[0001] This application claims benefit under 35 U.S.C. 119(e) to U.S. Provisional Patent Application 61/305,483, filed Feb. 17, 2010, which is incorporated by reference herein in its entirety.

[0002] 1. Field of the Invention

[0003] The present invention relates to heart valve delivery catheters and methods of delivering and implanting heart valves using delivery catheters. More specifically, the present invention relates to a delivery catheter with an improved distal tip assembly that is non-traumatic to surrounding body tissue during delivery and withdrawal of the catheter and prevents damage to an implanted prosthetic heart valve when the tip assembly is withdrawn through the implanted prosthetic heart valve.

[0004] 2. Background

[0005] Recently, minimally invasive approaches have been developed to facilitate catheter-based implantation of valve prostheses on the beating heart, intending to obviate the need for the use of classical sternotomy and cardiopulmonary bypass. For example, French Patent Application No. 99 14462 illustrates a technique and a device for the ablation of a deficient heart valve by percutaneous route, with a peripheral valvular approach. International Application (PCT) Nos. WO 93/01768 and WO 97/28807, as well as U.S. Pat. No. 5,814,097 to Sterman et al., U.S. Pat. No. 5,370,685 to Stevens, and U.S. Pat. No. 5,545,214 to Stevens illustrate techniques that are not very invasive as well as instruments for implementation of these techniques.

[0006] U.S. Pat. No. 3,671,979 to Moulopoulos and U.S. Pat. No. 4,056,854 to Boretos describe catheter-mounted artificial heart valves for implantation in close proximity to a defective heart valve. Both of these prostheses are temporary in nature and require continued connection to the catheter for subsequent repositioning or removal of the valve prosthesis, or for subsequent valve activation.

[0007] With regard to the positioning of a replacement heart valve, attaching a valve on a support with a structure in the form of a wire or network of wires, forming a frame, has been proposed. This frame can be contracted radially in such a way that it can be introduced into the body of the patient percutaneously by means of a catheter, and it can be deployed so as to be radially expanded once it is positioned at the desired target site. U.S. Pat. No. 3,657,744 to Ersek discloses a cylindrical, frame-supported, tri-leaflet tissue heart valve that can be delivered through a portion of the vasculature using an elongate tool. The frame is mounted onto the expansion tool prior to delivery to the target location where the frame and valve are expanded into place.

[0008] Current techniques for delivering prosthetic heart valves via a catheter include a transapical approach for aortic valve replacement, typically involving the use of an introducer port, i.e., a large-bore overtube, of a trocar. A crimped, framed valve prosthesis reversibly coupled to a delivery catheter is transcatheterally advanced toward the native valve, where it is either forcefully deployed using a balloon catheter, or, alternatively, passively deployed using a self-expandable system. Accurate positioning of the replacement valve in the native annulus is critical to the success of the implantation. Although prior delivery catheter assemblies are sufficient to delivery a prosthetic valve to the native annulus, they do not provide a precise release mechanism for the valve such that error in placing the prosthetic valve in the native annulus is reduced.

[0009] The present invention relates to a delivery catheter with an improved distal tip assembly for a heart valve delivery catheter. Delivery catheters according to embodiments of the present invention can include distal tip assemblies with a distal sheath and a proximal sheath, such that the distal portion of a prosthetic valve can be reoriented after partial release without causing trauma to the implantation site. Distal tip assemblies according to embodiments of the present invention can also include mechanisms for preventing damage to the implanted valve during withdrawal of a distal tip assembly through the valve. Delivery catheters according to the present invention can include a handle assembly having two or more rotatable control knobs on the catheter handle. These control knobs allows for accurate manipulation of the distal tip of the catheter. Delivery catheters according to embodiments of the present invention can also allow for further adjustment of the delivery position of a prosthetic valve retained by the distal tip of the catheter after a portion of the prosthetic valve has been exposed to the body channel.

[0010] The catheter assemblies described herein seek to remedy one or more of the disadvantages of previous heart valve delivery catheters by providing catheters that allow for precise control of the release point of a prosthetic heart valve within the body. The catheter assemblies provided herein can also include components that limit trauma to the body during reorientation after partial exposure of a prosthetic heart valve being delivered by the catheter. Partial exposure of a valve prior to implantation can be desirable because it allows for exposure of radiopaque markers so that the valve can be accurately positioned in the body prior to full expansion and implantation. The catheter assemblies described herein can also include components to limit trauma to the expanded prosthetic valve and body channels as the distal tip of the catheter is withdrawn through an implanted valve and thereafter from the body. In one embodiment, a catheter assembly according to the present invention includes a handle assembly, an introducer sheath, and a distal tip assembly. The handle assembly can include a fixed main handle and two or more rotating handles that allow a user to control the distal tip assembly of the catheter. The distal tip assemblies described herein can include a slotted tip for breaching the apex of the heart during a transapical delivery approach. Distal tip assemblies may also include two or more sleeves for retaining a prosthetic valve prior to deployment of the prosthetic valve. A valve retaining mechanism can be included to assist in retaining the prosthetic valve prior to deployment. Each control knob on the handle assembly controls a portion of the components on the distal tip of the catheter by allowing for precise manipulation of various delivery shafts. Each delivery shaft extends from the handle assembly to respective positions towards the distal end of the catheter. Preferably, rotating one of the control knobs causes a distal sleeve on the distal tip of the catheter to move in a distal direction, thereby at least partially releasing a prosthetic valve. Rotating a second one of the control knobs can cause a proximal sleeve on the distal tip of the catheter to move in a proximal direction, thereby fully releasing a self-expanding prosthetic valve at a desired location in the body. Once the valve is deployed, the catheter can be withdrawn from the body.

[0033] The following detailed description of heart valve delivery catheters and methods of delivering and implanting heart valves refers to the accompanying figures that illustrate exemplary embodiments. Other embodiments are possible. Modifications can be made to the embodiments described herein without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not meant to be limiting. Further, it would be apparent to one of skill in the art that the systems and methods described below can be implemented in many different embodiments of hardware. Any actual hardware described is not meant to be limiting. The operation and behavior of the systems and methods presented are described with the understanding that modifications and variations of the embodiments are possible given the level of detail presented. For example, while the description provided is directed to catheters for transapical delivery of a heart valve, the catheters and individual features of the catheters described herein should not be limited to transapical delivery of a heart valve. One of skill in the art would readily understand how to incorporate the features and structures described herein into catheters intended for other purposes. For example, features of the catheters described herein can be incorporated into catheters intended for other types of transluminal heart valve delivery as well as catheters intended for thorascopic heart valve delivery. Features of the catheters described herein can also be incorporated into catheters designed for delivery of stents or valves to areas of the body other than the heart.

[0034] FIG. 1 illustrates a catheter assembly 100 in accordance with one embodiment presented herein. Catheter assembly 100 is depicted in FIG. 1 in a closed configuration. Catheter assembly 100 generally includes a handle assembly 102 located at the proximal end of the catheter, a distal tip assembly 104 located at the distal end of the catheter, and an introducer 116 slidably located along a outer delivery shaft 106 between the distal tip assembly 104 and the handle assembly 102.

[0035] Outer delivery shaft 106 is preferably a tubular flexible braided structure. Outer delivery shaft 106 can be formed of braided material fabricated from materials such as, but not limited to, polyethylene naphthalate (PEN), polyester (PET), stainless steel, titanium, nitinol, cobalt nickel alloy, polyamide, polyimide, or the like. In some embodiments, outer delivery shaft may contain reinforcing materials or structures. These structures can include an inner layer of polymer overlaid by a first reinforcing braid layer, overlaid by a coil reinforcement, finally overlaid with an outside layer of polymeric material. In another embodiment, the inner layer of polymeric material is overlaid by the coil reinforcement, which is overlaid by the braided reinforcement, which is finally overlaid with the outside layer of a polymeric material. In other embodiments, the inner layer of polymeric material is overlaid by a braided layer, which is overlaid by the coil winding, which is overlaid by another layer of braid, which is in turn overlaid by an outer polymeric layer. Preferably, however, any reinforcing layer used allows outer delivery shaft 106 to retain a degree of flexibility. Other flexible materials can also be used to form outer delivery shaft 106 consistent with embodiments of the present invention.

[0036] Handle assembly 102 includes a main handle 108, a proximal control knob 110, and a distal control knob 112. Main handle 108, a proximal control knob 110, and distal control knob 112 can be formed of any suitable material. For example, in some embodiments the handle and control knobs are formed of a polymer material. Other materials are possible, as would be understood in the art. A flushing port 114 can also be included on main handle 108. Flushing port 114 can be used to de-air the catheter assembly. Also, the native annulus is exposed to the blood pressure in a patient's cardiovascular system during use of a heart valve delivery catheter. As a consequence, in the absence of any counter pressure in this annulus, blood can flow inside towards the proximal end of the catheter, where it may coagulate and cause thrombosis. Thus, flushing port 114 can also allow fluid to be introduced into the native annulus to prevent such complications. In some embodiments, flush port 114 can also be used for site specific drug delivery or to introduce radiopaque fluid into the body.

[0037] As will be described herein, proximal control knob 110, and distal control knob 112 can be manipulated by a user in order to control operation of the distal tip assembly 104 of catheters described herein. A detailed description of the operation and structure of handle assembly 102 is provided below, particularly with reference to FIGS. 5-10. Distal tip assembly 104 includes a tip 122, which is preferably slotted for the reasons described herein, a tip connector 124, and a support arm sleeve 126. A flushing tap 118 and a flushing tap lead 120 can be connected to an introducer 116. Introducer 116 is preferably a tubular member that is slidably located over outer delivery shaft 106. Introducer 116 may be formed of a variety of materials, for example, stainless steel or various polymer materials. A detailed description of the operation and structure of distal tip assembly 104 and introducer 116 is provided below, particularly with reference to FIGS. 2-4 and 8-12. Catheter 100 is configured to be advanced along a guide wire (not shown). Preferably, the catheter is advanced over a 0.035 inch guide wire. However, the dimensions of the catheter components can be adjusted for advancement over guide wires with larger or smaller diameters.

[0038] FIG. 2 illustrates catheter assembly 100 in an open configuration. Catheter assembly 100 reaches the open configuration when introducer 116 is moved proximally along outer delivery shaft 106 to expose a valve retaining sleeve 204, a valve retaining sleeve connector 208, and tip guard 202 of distal tip assembly 104. Valve retaining sleeve connector 208 secures valve retaining sleeve 204 to the distal end of the outer delivery shaft 106. The outer delivery shaft 106 therefore extends from the interior of handle assembly 102 to sleeve connector 208. Slotted tip 122 and tip guard 202 are positioned on and connected to the distal end of an intermediate delivery shaft 206. Intermediate delivery shaft 206 extends from the interior of handle assembly 102 to slotted tip 122, to which the distal end of intermediate delivery shaft 206 is attached. Intermediate delivery shaft 206 is encompassed by outer delivery shaft 106 from the interior of handle assembly 102 until the outer delivery shaft 106 ends at sleeve connector 208. Tip guard 202 is preferably attached to the proximal end of slotted tip 122. In other embodiments, tip guard 202 can be attached directly to intermediate shaft 206. Intermediate shaft 206 is preferably a tubular member.

[0039] A guide wire shaft 504 (shown in FIG. 5) is encompassed within intermediate shaft 206 and extends from the inside of handle assembly 102 to the proximal end of slotted tip 122. Thus, in one embodiment of the present invention, at least three shafts extend from the main handle, and the shafts are nested along at least a part of their lengths. Specifically, guide wire shaft 504 is encompassed by the intermediate delivery shaft 206 from a position inside of handle assembly 102 to the interior of slotted tip 122, which is preferably hollow through at least a portion thereof. Intermediate delivery shaft 206 is connected to, and ends, at the proximal end of slotted tip 122. In turn, intermediate delivery shaft 206 is encompassed by the outer delivery shaft 106 from a position inside of handle assembly 102 to the valve retaining sleeve connector 208. Outer delivery shaft 106 is connected to, and ends, at the retaining sleeve connector 208. Intermediate shaft 206 and guide wire shaft 504 can be constructed of various polymer materials, and may be braided structures using materials described above with reference to outer delivery shaft 106.

[0040] FIG. 3 is a depiction the distal tip assembly 104 and introducer 116 of a catheter according to one embodiment of the present invention in a closed configuration. Introducer 116, valve retaining sleeve 204, support arm sleeve 126, and tip connector 124 are rendered transparent in FIG. 3 in order to facilitate description of certain components. Tip connector 124 is slidably positioned over the proximal end of slotted tip 122, as will be detailed below with reference to FIG. 4. Tip connector 124 is preferably formed of a soft flexible material to prevent trauma during delivery of the distal tip assembly 104 into the body and withdrawal from the body after implantation of a prosthetic valve. The flexible nature of tip connector 124 can also allow the tip connector to readily bend and contort with a guide wire during introduction into the body channel. Tip connector 124 is preferably cone shaped to avoid blunt edges on the advancing end of catheter 100. It is understood that tip connector 124 can be formed in other shapes, for example, tip connector 124 can be semi-spherically shaped, or any other shape resulting in a gradual transition from the smaller diameter of slotted tip 122 to the larger diameter of support arm sleeve 126.

[0041] The distal end of intermediate delivery shaft 206 is connected to slotted tip 122. A simplified rendering of a prosthetic heart valve 304 is shown attached to a valve retainer 302. Valve retainer 302 is also connected to intermediate delivery shaft 206. Valve retainer 302 serves to retain prosthetic valve 304 in place during delivery to the desired location within a patient. Valve retainer 302 can be made from a polymer or metal material suitable for exposure to a patient's circulatory system. Prosthetic valve 304 preferably has a frame that is formed from a self-expanding material, for example, Nitinol. This material allows the structure to be contracted radially at a temperature different from that of the body of the patient and to regain its original expanded shape when its temperature approaches or reaches that of the body of the patient. The valve portion of prosthetic valve 304 can be made of biological tissue, such as bovine or porcine pericardium, or from synthetic materials. When in a closed configuration, at least a portion of prosthetic valve 304, and valve retainer 302, are encompassed by valve retaining sleeve 204, and valve retaining sleeve 204 is in turn encompassed by introducer 116. In this configuration, the distal end of introducer 116 abuts the proximal end of support arm sleeve 126.

[0042] FIG. 4 illustrates the distal tip assembly 104 of a catheter in accordance with one embodiment presented herein in a partially open configuration. As shown in FIG. 4, tip connector 124 is affixed to the guide wire shaft 504 (not shown in FIG. 4) via a connecting fin 404. Connecting fin 404 is attached to the distal end of guide wire shaft 504. An axial slot (not shown) in slotted tip 122 allows the connecting fin 404 to slide axially along slotted tip 122 when guide wire shaft 504 is moved in a distal direction. Slotted tip 122 is preferably formed of a flexible material to prevent trauma to the body. The flexibility of slotted tip 122 allows the slotted tip 122 to closely follow a guide wire, over which the distal tip of catheter 100 is advanced into the body. As noted above, slotted tip 122 is affixed to the distal end of intermediate delivery shaft 206. The proximal end of intermediate delivery shaft 206 is preferably fixed in a stationary position inside handle assembly 102. Thus, slotted tip 122 and tip guard 202, which is preferably connected to the proximal end of slotted tip 122, are held in a fixed position by intermediate delivery shaft 206 when guide wire shaft 504 is moved in an axial direction. In one embodiment, tip connector 124 is affixed to connecting fin 404 by over-molding the tip connector 124 around the connecting fin 404. It is understood that tip connector 124 can be affixed to fin 404 by any one of several suitable methods, such as a tongue and groove assembly, gluing, etc. The distal end of support aim sleeve 126 is connected to the proximal end of tip connector 124 so that the support arm sleeve 126 and tip connector 124 move together. In the configuration shown in FIG. 4, intermediate delivery shaft 206 has been advanced distally while outer delivery shaft 106 is retained in a fixed position.

[0043] FIG. 5 illustrates one embodiment of a delivery catheter handle assembly 102 that can be used to control delivery of a prosthetic heart valve using embodiments of distal tip assemblies according to the present invention. Handle assembly 102 includes a main handle 108, a rotatable proximal control knob 110, and a rotatable distal control knob 112. The handle sections of handle assembly 102 are preferably connected using O-rings (not shown). As seen in FIG. 7, knob pins 714 on the distal end of handle assembly 102 locate distal control knob 112 on handle assembly 102. A circular channel (not shown) is formed on the interior surface of distal control knob 112, and the channel receives knob pins 714, thereby preventing movement of distal control knob 112 in an axial direction while permitting rotation of distal control knob 112 around the longitudinal axis of handle assembly 102. Knob pins 716 located under the proximal end of proximal control knob 110 locate proximal control knob 110 on handle assembly 102. A circular channel (not shown) is formed on the interior surface of proximal control knob 110, and the channel receives knob pins 716, thereby preventing movement of proximal control knob 110 in an axial direction while permitting rotation of proximal control knob 110 around the longitudinal axis of handle assembly 102. It is understood that the handle sections can be connected using other mechanisms that would allow movement of the sections relative to each other. Other structures can be used to secure control knobs 110 and 112 to handle assembly 102 to prevent axial movement thereof. For example, circular ridges can be provided in handle assembly in place of pins 714 and 716 in order to mate with the circular grooves formed on the interior surfaces of knobs 110 and 112. A ratchet system can also be used to rotatably secure control knobs 110 and 112 to handle assembly 102. Both proximal control knob 110 and distal control knob 112 are threaded on their interior surfaces, as shown in further detail in FIG. 6. The configuration of the handle assembly 102 allows a user to precisely control the movement of the guide wire shaft 504 and the outer delivery shaft 106, and thereby manipulate the components of distal tip assembly 104.

[0044] As shown in FIGS. 5-7 handle assembly 102 includes a distal guide wire shaft boss 616 configured to engage the inner threads 602 of the distal control knob 112. Specifically, distal guide wire shaft boss 616 preferably has a tongue 617 that engages inner threads 602 of distal control knob 112. Inner threads 602 are formed such that, as distal control knob 112 is rotated in a clockwise direction by a user, distal guide wire shaft boss 616 is forced in a distal direction, that is, towards the distal end of handle assembly 102. Distal guide wire shaft boss 616 is connected to proximal guide wire shaft boss 608 by connecting bar 510. Proximal guide wire shaft boss 608 is connected to guide wire shaft 504. Therefore, in operation, clockwise rotation of distal control knob 112 moves distal guide wire shaft boss 616 towards the distal end of handle assembly 102. Because distal guide wire shaft boss 616 is coupled to guide wire shaft 504 through connecting bar 510 and proximal guide wire shaft boss 608, guide wire shaft 504 moves in a distal direction when distal guide wire shaft boss 616 moves in a distal direction. Although a specific manner of connecting distal guide wire shaft boss 510 to guide wire shaft 504 is described above, it is understood that in other embodiments of the present invention, alternate mechanisms can be used to ensure that rotation of distal control knob 112 results in axial movement of guide wire shaft 504.

[0045] Handle assembly 102 further includes an outer delivery shaft boss 612 configured to engage the inner threads 604 of the proximal control knob 110. Specifically, outer delivery shaft boss 612 preferably has a tongue 618 that engages inner threads 604 of proximal control knob 110. Outer delivery shaft boss 612 is connected to outer delivery shaft 106. In operation, counter-clockwise rotation of proximal control knob 110 moves outer delivery shaft boss 612 towards the proximal end of handle assembly 102. Because outer delivery shaft boss 612 is coupled to outer delivery shaft 106, outer delivery shaft 106 moves in a proximal direction when proximal control knob 110 moves in a proximal direction. Although a specific manner of connecting outer delivery shaft boss 612 to outer delivery shaft 106 is described above, it is understood that in other embodiments of the present invention, alternate mechanisms can be used to ensure that rotation of outer delivery shaft boss 612 results in axial movement of outer delivery shaft 106.

[0046] Handle assembly 102 also includes an intermediate delivery shaft 206. Intermediate delivery shaft 206 is fixedly secured to the inside of main handle 108, preferably by an O-ring. It is understood that intermediate delivery shaft 206 can be secured to main handle 108 by other methods, for example, by welding, bolting, over-molding, etc. Guide wire shaft 504 is encompassed by, but not affixed to, intermediate delivery shaft 206 such that guide wire shaft 504 is axially movable with respect to intermediate delivery shaft 206. Intermediate delivery shaft 206 is encompassed by, but not affixed to, outer delivery shaft 106 such that outer delivery shaft 106 is axially movable with respect to intermediate delivery shaft 206. The entire catheter assembly 100 can be placed over a pre-positioned guide wire (not shown) by sliding guide wire shaft 504 over the guide wire and out of guide wire port 512. Guide wire port 512 can also be used as a supplemental flushing port. Handle assembly 102 further includes a flushing channel 502 located within main handle 108. Flushing channel 502 is fluidly connected to the space between outer delivery shaft 106 and intermediate delivery shaft 206 and the space between intermediate delivery shaft 206 and guide wire shaft 504. Flushing channel 502 is fluidly connected to flushing port 114. In some embodiments, flushing channel 502 is fluidly connected to guide wire port 512 in addition to, or instead of, flushing port 114.

[0047] At the beginning of a procedure distal guide wire shaft boss 616 is positioned towards the distal end of handle assembly 102, near distal control knob pins 714, and outer delivery shaft boss 612 is positioned towards the proximal end of its movement area, near proximal control knob pins 716. When bosses 616 and 612 are in these initial positions, distal tip assembly 104 is generally in the configuration shown in FIG. 3, although distal tip assembly 104 could be previously advanced out of introducer 116. When in a closed configuration, heart valve 304 and valve retainer 302 are encompassed by valve retaining sleeve 204, and valve retaining sleeve 204 is in turn encompassed by introducer 116. In this configuration, the distal end of introducer 116 abuts the proximal end of support arm sleeve 126. Upon introduction into a body channel, distal tip assembly 104 is moved forward while introducer 116 is held at a fixed position, preferably at the apex of the heart after a minithoracotomy procedure, and distal tip assembly 104 is advanced until prosthetic valve 304 reaches a desired implant location, preferably the native valve annulus.

[0048] FIGS. 8-10 illustrate distal tip assembly 104 in three stages of delivery. In FIG. 8, distal tip assembly has been advanced within the body such that prosthetic valve 304 is positioned and oriented approximately in the native valve location. Distal tip assembly 104 is shown in FIG. 8 in a position that is reached after distal control knob 112 of handle assembly 102 has been rotated in a clockwise direction by a user in order to partially advance distal guide wire shaft boss 616, and thereby guide wire shaft 504, towards the distal end of handle assembly 102. At the stage of delivery shown in FIG. 8, distal guide wire shaft boss 616, and thereby guide wire shaft 504, have not reached their maximum distal position. Advancing guide wire shaft 504 in a distal direction causes connecting fin 404, tip connector 124, and support arm sleeve 126 to advance in a distal direction over slotted tip 122, and away from valve retaining sleeve 204, which remains in its original position because proximal control knob 110 has remained in its original position. Slotted tip 122 is also held stationary during movement of tip connector 124 and support arm sleeve 126 because it is connected to intermediate delivery shaft 206, which is anchored in handle assembly 102. As shown in FIG. 8, valve prosthesis arms 802 are partially exposed, but the support arm sleeve 126 is covering the distal end of arms 802. A radiopaque marker can be included or incorporated into valve prosthesis arms 802 in order to assist in properly orienting and positioning prosthetic valve 304 at a desired location in the body. It is understood that more than one radiopaque marker can be used if desired. Uncovering the valve prosthesis aims 802 from support arm sleeve 126 and valve retaining sleeve 204 allows for improved detection of the location and orientation of valve prosthesis arms 802 by exposing the radiopaque marker to the body channel. Furthermore, because the distal end of valve prosthesis arms 802 remain inside support arm sleeve 126, the orientation of prosthetic valve 304 in the body can be adjusted without the risk of valve prosthesis arms 802 contacting and thereby causing trauma to body tissue.

[0049] To achieve the configuration of distal tip assembly 104 shown in FIG. 9, distal control knob 112 of handle assembly 102 is further rotated in a clockwise direction in order to advance distal guide wire shaft boss 616, and thereby guide wire shaft 504, to their maximum distal location, that is, the location closest to distal control knob pins 714. This distal movement of distal guide wire shaft boss 616 advances connecting fin 404, tip connector 124, and support arm sleeve 126 further distally, fully releasing valve prosthesis aims 802 from support arm sleeve 126. The proximal portion of valve 304, as well as valve retainer 302, remains encompassed by valve retaining sleeve 204. Because tip connector 124 is formed of a soft flexible material and has no blunt edges due to its conical shape, trauma to the body is prevented as support arm sleeve 126 slides down slotted tip 122. Tip connector 124 can also be formed in other shapes, for example, tip connector 124 can be semi-spherically shaped, or any other shape resulting in a gradual transition from the smaller diameter of slotted tip 122 to the larger diameter of support arm sleeve 126. In addition, due to their flexibility, tip connector 124 and support arm sleeve 126 can bend with slotted tip 122 and guide wire shaft 504, thereby limiting contact with and trauma to surrounding body tissue such as the walls of the aortic arch. Slotted tip 122 and tip guard 202, which are fixed to intermediate delivery shaft 206, remain stationary in the body as the support arm sleeve 126 advances distally. As a result, tip guard 202 protrudes from the proximal end of support arm sleeve 126 after support arm sleeve 126 is advanced to its furthest distal location.

[0050] In other embodiments of the present invention, distal tip assembly 104 can be formed without slotted tip 122. In such embodiments, tip guard 202 is attached directly to intermediate shaft 206. Tip connector 124 can be narrowed and elongated at its distal end in order to receive the distal end of guide wire shaft 504. As in the embodiments described above, tip guard 202 is encompassed by support arm sleeve 126 during delivery of the distal tip assembly to an implantation location in the body. As guide wire shaft 504 is advanced by manipulation of a handle in the manner described above, support arm sleeve 126 and the elongated tip connector 124 move in a distal direction while the tip guard 202 remains stationary, thereby exposing tip guard 202 on the proximal end of support arm sleeve 126. Tip guard 202 then functions as a non-traumatic leading edge for support arm sleeve 126 during withdrawal of the distal tip assembly 104 from the body, as described above.

[0051] The clockwise and counterclockwise rotations of distal control knob 112 and proximal control knob 110 described above are merely exemplary. In embodiments of the present invention, the rotation of control knobs 110 and 112 can be reversed, and control knobs 110 and 112 can be rotated in the same direction. Inner threads 602 and 604 can be adjusted accordingly to ensure that guide wire shaft 504 and outer delivery shaft 106 move in the desired axial direction based on the rotational direction of control knobs 110 and 112.

[0052] To achieve the configuration of distal tip assembly 104 shown in FIG. 10, proximal control knob 110 of handle assembly 102 is rotated in a counterclockwise direction in order to move outer delivery shaft boss 612 in a proximal direction, thereby withdrawing outer delivery shaft 106, valve retaining sleeve 204, and valve retaining sleeve connector 208 in a proximal direction. As noted above, valve retainer 302 is fixed to intermediate delivery shaft 206, and therefore does not experience axial movement when outer delivery shaft 106 or guide wire shaft 504 are manipulated. In this configuration, valve 304 is fully released from the inside of valve retaining sleeve 204. The distal end of valve retaining sleeve 204 partially covers valve retainer 302. Once released from valve retaining sleeve 204, self-expanding prosthetic valve 304 expands to its open position in the native annulus.

[0053] After valve prosthesis 304 has been delivered to the native annulus, distal tip assembly 104 is prepared for removal from the body. Distal tip assembly 104 is withdrawn through the expanded valve prosthesis 304 in the configuration shown in FIG. 11. Support arm sleeve 126 and tip connector 124 remain in their distal position along slotted tip 122 during withdrawal of distal tip assembly 104. As a result, support arm sleeve 126 is positioned distally to tip guard 202. Tip guard 202 thereby forms the leading edge of support sleeve 126 during withdrawal of the distal tip assembly from the body. Tip guard 202 provides a smooth, non-snagging surface to aid in withdrawing support arm sleeve 126 through the expanded valve 304 without damaging the valve. Tip guard 202 also prevents injuries to body channels as the distal tip assembly 104 is withdrawn from the body. Tip guard 202 is preferably formed of a semi-spherical member, as best seen in FIGS. 9-11. However, in other embodiments of the present invention, tip guard 202 can take alternate forms. For example, tip guard 202 can be a gently sloping cone or a semi-ellipsoid shaped member in order to prevent support arm sleeve 126 and other components from snagging on prosthetic valve 304 as the catheter is removed from a patient's body. Tip guard 202 is preferably formed of a relatively soft, flexible material to further reduce the risk of trauma to the implanted prosthetic valve 304 and body tissue. For example, tip guard 202 can be made from any semi-rigid polymer or other flexible materials suitable for exposure to a patient's circulatory system. Preferably, the diameter of the base of tip guard 202 is approximately equal to the inner diameter of support arm sleeve 126. In other embodiments, tip guard 202 can have a slightly larger diameter than support arm sleeve 126. Support arm sleeve 126 can then be advanced past the distal end of tip guard 202. In such embodiments, when the distal end of tip guard 202 is released from support arm sleeve 126, the larger diameter of tip guard 202 ensures that the leading edge of support arm sleeve 126 does not damage the implanted prosthetic valve or body tissue during withdrawal of the distal tip assembly 104.

[0054] FIG. 12 illustrates the distal tip assembly 104 and introducer 116 shown in FIG. 3 in a second stage of withdrawal. In this stage, distal tip assembly 104 has been withdrawn to the apex of the heart. Tip guard 202, valve retainer 302, valve retaining sleeve 204, and valve retaining sleeve connector 208 are encompassed by introducer 116. The distal end of introducer 116 mates with tip guard 202 and abuts the proximal end of support arm sleeve 126 in order to form a closed system. Introducer 116 and distal tip assembly 104 are then removed from the body.

[0055] A method of implanting a heart valve via a transapical approach using a catheter according to one embodiment of the present invention will be described with reference to FIG. 13. First, in step 1301, a patient's chest and heart apex are prepped for an implantation procedure, preferably by minithoracotomy or a similar procedure. Various preparation procedures that provide access to the heart can also be used in embodiments of the present invention. For example, hemisternotomy or sternotomy can be used to gain access to the heart, although these procedures are less desirable because they are more invasive than minithoracotomy and can result in extended post-operative recovery times. In step 1302, the user de-airs the catheter assembly 100 and places the catheter assembly 100 over a guide wire and advances the distal tip assembly 104 through the minithoracotomy and to the apex of the heart. Slotted tip 122 penetrates the apex of the heart to allow access to the interior of the heart. In step 1303, the user positions introducer 116 across the apex of the heart, and advances the distal tip assembly 104 distally while holding the introducer stationary. In step 1304, distal tip assembly 104 is advanced until the prosthetic valve 304 is correctly positioned and oriented in the native valvular annulus.

[0056] Steps 1305 through 1307 release the prosthetic valve 304 from the distal tip assembly 104. In step 1305, the user rotates distal control knob 602 to move the support arm sleeve 126 distally to release the proximal end of valve prosthesis arms 802. Note that the distal portion of valve prosthesis arms 802 are still contained within support arm sleeve 126, which allows the user to retract the arms 802 if the prosthetic valve 304 is not correctly positioned. If the user is satisfied that prosthetic valve 304 is properly positioned and oriented, the user further rotates the distal control knob 602 (step 1306) to advance support arm sleeve 126 further distally. This fully releases the valve prosthesis arms 802 from support arm sleeve 126. Then, in step 1307, the user retracts the valve retaining sleeve 204 by rotating the proximal control knob 110, allowing the prosthetic valve 304 to fully expand in the native annulus.

[0057] In steps 1308-1310, the distal tip assembly 104 and introducer 116 are removed from the body. First, in step 1308, tip guard 202, support aim sleeve 126, tip connector 124, and slotted tip 122 are pulled back through the valve 304. Tip guard 202 prevents the support arm sleeve 126 from snagging on and damaging valve 304. In step 1309, distal tip assembly 104 is withdrawn into introducer 116, which encloses the device. The introducer 116 and distal tip assembly 104 are then withdrawn from the heart and from the body (step 1310). The body can then be closed up in the conventional fashion (step 1311).

[0058] Although the method described with reference to FIG. 13 has been described with reference to a transapical approach, components and methods according to embodiments of the present invention can be used in conjunction with catheters designed for alternate approaches. For example, distal tip assembly 104 and handle assembly 102, or components thereof, can be used in catheters designed for delivery of a heart valve via a transfemoral approach.

[0059] FIG. 14 is a depiction of tip connector assembly 1424 in accordance with one embodiment of the present invention. Tip connector assembly 1424 includes a ring 1430. Tip connector assembly 1424 is comparable to tip connector 124, which is shown in FIG. 1. Ring 1430 can be disposed at distal end 1426 of tip connector assembly 1424 and serves to reinforce distal end 1426. Ring 1430 serves to minimize deformation of distal end 1426 during percutaneous delivery and withdrawal of a heart valve.

[0060] Ring 1430 can be made of metal, plastic, or any other suitable material to add rigidity to and reinforce distal end 1426 of tip connector assembly 1424. Ring 1430 can be circular, as shown in FIG. 14, or any other suitable shape, such as elliptical or rectangular. Further, ring 1430 can be a closed shape, such as the closed circle shown in FIG. 14, or in other embodiments, can form an open shape, such as a partial arc of a circle. Ring 1430 can be sized to be flush with an outside surface of tip connector base 1425. For example, ring 1430 can be disposed within a groove or recess formed in tip connector assembly 1424. Moreover, ring 1430 can be completely or partially encapsulated to avoid surface area exposure of ring 1430 or to provide a flush surface between ring 1430 and tip connector assembly 1424. Ring 1430 can be fixedly attached, removably coupled, and/or axially rotatably coupled to tip connector assembly 1424. FIG. 15 is a depiction of ring 1430 separated from tip connector assembly 1424 of FIG. 14.

[0061] FIG. 16 illustrates an exploded view of a tip connector assembly 1600 in accordance with one embodiment of the present invention. Tip connector assembly 1600 comprises a tip connector body 1620 and an insert 1610. Insert 1610 is sized and shaped to fit snugly inside of a distal end of tip connector body 1620.

[0062] FIG. 17 is a depiction of insert 1610 of tip connector assembly 1600. Insert 1610 comprises a first portion 1732, a second portion 1710, and a lumen 1726. Second portion 1710 is disposed on a proximal end of insert 1610 and is sized to fit snugly against an inside surface of tip connector body 1620. As seen in FIG. 17, the diameter of first portion 1732 is larger than the diameter of second portion 1710. First portion 1732 is disposed on a distal end of insert 1610 and is sized to be flush with an outside surface of tip connector base 1620 when second portion 1710 is positioned inside tip connector body 1620. Insert 1610 can be fixedly attached, removably coupled, or axially rotatably coupled to tip connector body 1620.

[0063] Similar to ring 1430, insert 1610 serves to minimize deformation of the distal end of tip connector body 1620 when the forces are applied to the distal end of a catheter including tip connector assembly 1600 during percutaneous delivery and withdrawal of a prosthesis by means of a catheter.

[0064] FIG. 18 is a depiction of tip connector assembly 1600 with insert 1610 inserted into tip connector body 1620.

[0065] FIG. 19 is a depiction of a distal tip 1900 of a catheter according to one embodiment of the present invention. Distal tip 1900 can be constructed of a single piece of material to form the slotted tip, tip connector, and support arm sleeve of other embodiments described herein, such as the embodiment shown in FIG. 3. Because distal tip 1900 is a single piece of material, there are no gaps formed between the connection surfaces of the slotted tip and tip connector or between the tip connector and the support arm sleeve when distal tip 1900 is deformed during use. Distal tip 1900 can be made of any suitable material, such as plastic or silicone. In other embodiments, distal tip 1900 can be formed by fixedly attaching a slotted tip, tip connector, and support arm sleeve into a single piece using, for example, adhesive, fusing, or a friction fit.

[0066] FIG. 20 is a depiction of a distal tip assembly 2000 according to one embodiment of the present invention. Distal tip assembly 2000 comprises slotted tip 2022, tip connector 2024, and distal tip insert 2010. Distal tip insert 2010 is sized to be disposed between slotted tip 2022 and tip connector 2024.

[0067] FIG. 21 is a depiction of distal tip insert 2010 of distal tip assembly 2000. Distal tip insert comprises first portion 2012, second portion 2104, third portion 2106, and aperture 2108. As shown in FIG. 21, the diameters corresponding to first portion 2012 and third portion 2106 are smaller than the diameter corresponding to second portion 2105. Aperture 2108 is sized to fit around slotted tip 2022 in order to allow for axial sliding movement relative to slotted tip 2022. First and third diameter portions 2102 and 2106 are sized to provide a gap between their respective diameters and the inside surface of distal tip insert 2010. Second diameter portion 2104 is designed to engage with the inside surface of distal tip insert 2010 to ensure that distal tip insert 2010 maintains a minimum diameter and does not deform during use.

[0068] The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Other modifications and variations may be possible in light of the above teachings. The embodiments and examples were chosen and described in order to best explain the principles of the invention and its practical application and to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention.

[0069] The following paragraphs serve as examples of the above-described embodiments.

[0070] Another embodiment provides a distal tip assembly for a catheter having a distal end and a proximal end. The distal tip assembly includes a flexible tip having a semi-spherical tip guard positioned at the proximal end of the flexible tip. A first valve retaining sleeve is included. The first valve retaining sleeve is configured to be axially movable over the flexible tip from a proximal position to a distal position. A second valve retaining sleeve is positioned proximally to the first valve retaining sleeve. The second valve retaining sleeve is axially moveable with respect to the first valve retaining sleeve. The semi-spherical tip guard is encompassed by the first valve retaining sleeve when the first valve retaining sleeve is in its proximal position, and the semi-spherical tip guard is exposed on the proximal side of the first valve retaining sleeve when the first valve retaining sleeve is in its distal position. A flexible connector having a proximal end and a distal end is provided. The proximal end of the flexible connector is attached to the distal end of the first valve retaining sleeve, and the flexible connector decreases in diameter across its length from the proximal end to the distal end.

[0071] Another embodiment provides a method of implanting a prosthetic valve into a heart. The method includes obtaining a catheter, the catheter having a distal tip assembly including a replacement valve, a first retaining sleeve positioned over a distal end of the replacement valve, a second retaining sleeve positioned over the proximal end of the replacement valve, and a semi-spherical tip guard. The replacement valve is then delivered to an implantation site in the heart using the catheter. The first retaining sleeve is advanced in a distal direction to expose a portion of the replacement valve, such that the distal tip of the replacement valve remains covered by the first retaining sleeve. The first retaining sleeve is further advanced in a distal direction to release the distal tip of the replacement valve, and the second retaining sleeve is retracted in a proximal direction to release the remainder of the replacement valve.