Patent Description:
The present disclosure concerns implementations of a delivery apparatus for use with catheter-based technologies to introduce a prosthetic device, such as a heart valve or other implant, into the patient's vasculature.

Prosthetic cardiac valves have been used for many years to treat cardiac valvular disorders. The native heart valves (such as the aortic, pulmonary and mitral valves) serve critical functions in assuring the forward flow of an adequate supply of blood through the cardiovascular system. These heart valves can be rendered less effective by congenital, inflammatory or infectious conditions. Such damage to the valves can result in serious cardiovascular compromise or death. For many years the definitive treatment for such disorders was the surgical repair or replacement of the valve during open heart surgery, but such surgeries are prone to many complications. More recently a transvascular technique has been developed for introducing and implanting a prosthetic heart valve using a flexible catheter in a manner that is less invasive than open heart surgery.

In this technique, an introducer sheath can be used to safely introduce a delivery apparatus into a patient's vasculature (e.g., the femoral artery). An introducer sheath generally has an elongated sleeve that is inserted into the vasculature and a 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 prosthetic valve is then mounted in a crimped state on the end portion of a flexible catheter and advanced through a blood vessel of the patient via the introducer sheath until the prosthetic valve reaches the implantation site. The prosthetic valve at the catheter tip is then expanded to its functional size at the site of the defective native valve such as by inflating a balloon on which the prosthetic valve is mounted. Alternatively, the prosthetic valve can have a resilient, self-expanding stent or frame that expands the prosthetic valve to its functional size when it is advanced from a delivery sheath at the distal end of the catheter.

Balloon-expandable prosthetic valves can be used when replacing calcified native valves. Advantageously, the catheter balloon can apply sufficient expanding force to anchor the frame of the prosthetic valve to the surrounding calcified tissue. Self-expanding prosthetic valves can be used to replace a defective, non-stenotic (non-calcified) native valve, although they also can be used to replace stenotic valves. One drawback associated with implanting a self-expanding prosthetic valve is that as the operator begins to advance the prosthetic valve from the open end of the delivery sheath, the prosthetic valve tends to "jump" out very quickly from the end of the sheath; in other words, the outward biasing force of the prosthetic valve's frame tends to cause the prosthetic valve to be ejected very quickly from the distal end of the delivery sheath, making it difficult to deliver the prosthetic valve from the sheath in a precise and controlled manner and increasing the risk of trauma to the patient. Additionally, during a procedure it may be necessary to reposition and/or withdraw the prosthetic valve if the valve is deployed in the wrong location or appears incompatible with the patient anatomy. However, there are several problems with (fully or partially) re-sheathing a self-expanding prosthetic valve. For example, as the implant exhibits larger outward radial forces the smaller is constrained, making it more difficult to deploy and retract. The implant may also compress in unpredictable and non-uniform ways, causing it to get stuck in the sheath and potentially become unusable/incapable of being redeployed. Thus, there remains a need for further improvements in delivery catheters used in endovascular systems used for implanting and repositioning heart valves and other prosthetic devices.

<CIT> discloses a recapturing sheath which comprises an elongate shaft having a proximal end and a distal end. The shaft defines a lumen therein. The distal end comprises a flare and a slit. A first portion of said flare overlaps a second portion of said flare (cf. <CIT> discloses a delivery sheath including an elastic outer tubular layer and an inner tubular layer having a thick wall portion integrally connected to a thin wall portion.

The claimed invention is defined in independent claim <NUM> and relates to a delivery sheath system for percutaneous delivery and implantation of a self-expanding prosthetic heart valve. Preferred configurations of the claimed invention are defined in dependent claims <NUM> to <NUM>. Also described herein are related examples, embodiments and arrangements useful for understanding the claimed invention.

Certain examples in the present disclosure provide a prosthetic valve (e.g., a prosthetic heart valve) and a valve delivery apparatus for delivery of the prosthetic 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 diseased native aortic valve. The delivery apparatus in particular implementations is configured to deploy a prosthetic valve from a delivery sheath in a precise and controlled manner at the target location within the body.

Another example delivery sheath system disclosed herein comprises a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member. A tip portion is provided at the distal end of the sheath member, the tip portion having a central lumen extending therethrough. At least one cross-sectional segment of an inner surface of the tip portion includes alternating portions of concave and convex curvature.

Also disclosed herein is a method of deploying a prosthetic heart valve that comprises inserting an introducer sheath into a blood vessel and inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein. The delivery sheath comprising a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member, and a tip portion provided at the distal end of the sheath member, the tip portion having a central lumen extending therethrough, wherein at least one cross-sectional segment of an inner surface of the tip portion includes alternating portions of concave and convex curvature. The prosthetic valve is advanced through the tip portion to a treatment site such that the prosthetic valve at least partially expands within the tip portion. The alternating portions of concave and convex curvature facilitate directed expansion of the prosthetic heart valve as it passes through the tip portion.

Another example delivery sheath system disclosed herein comprises a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member, a ring portion provided at the distal end of the sheath member, and a tip portion extending from a distal end of the ring portion. The tip portion includes a longitudinally extending folding region movable between a folded and unfolded configuration. In the folded configuration, the tip portion creases along a longitudinally extending edge such that circumferential portions of the tip portion at least partially overlap. In the unfolded configuration, the tip portion defines an increasing tapered surface having a larger diameter at a distal end of the tip portion.

Further disclosed herein is a method of deploying a prosthetic valve that comprises inserting an introducer sheath into a blood vessel and inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein. The delivery sheath comprises a sheath member that defines a tubular structure extending between a proximal end and a distal end of the sheath member, a ring portion provided at the distal end of the sheath member, and a tip portion extending from a distal end of the ring portion. The tip portion includes a longitudinally extending folding region movable between a folded and unfolded configuration. In the folded configuration, the tip portion creases along a longitudinally extending edge such that circumferential portions of the tip portion at least partially overlap. In the unfolded configuration, the tip portions defines an increasing tapered surface having a larger diameter at a distal end of the tip portion. The prosthetic valve is advanced through the distal end of the sheath member, to the ring portion, through the ring portion to the tip portion, through the tip portion such that the prosthetic valve at least partially expands within the tip portion and the tip portion moves from the folded to the unfolded configuration in response to the outward directed radial force of the prosthetic heart valve passing through the tip portion. The prosthetic valve is then advanced beyond a distal end of the delivery sheath to a treatment site.

Another example delivery sheath disclosed herein comprises: a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member and a tip portion provided at the distal end of the sheath member. The tip portion has a central lumen extending therethrough. The tip portion is discontinuous and has two flaps extending circumferentially around the tip portion. The tip portion is movable between an unexpanded and an expanded configuration. In the unexpanded configuration, the tip portion defines a constant diameter along its length. In the expanded configuration, the tip portion flares open increasing a diameter of the distal end of the tip portion and increasing the spacing between the two flaps.

An example method of deploying a prosthetic valve disclosed herein comprises inserting an introducer sheath into a blood vessel, inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein. The delivery sheath comprises a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member, a tip portion provided at the distal end of the sheath member, the tip portion having a central lumen extending therethrough. The tip portion is discontinuous and has two flaps extending circumferentially around the tip portion. The tip portion is movable between an expanded and an unexpanded configuration. In the unexpanded configuration, the tip portion defines a constant diameter along its length. In the expanded configuration, the tip portion flares open increasing a diameter of the distal end of the tip portion and increasing the spacing between the two flaps. The prosthetic valve is advanced through the distal end of the sheath member, to the tip portion, through the tip portion to a treatment site such that the prosthetic valve at least partially expands within the tip portion and the tip portion moved from the unexpanded to the expanded configuration in response to the outward directed radial force of the prosthetic heart valve passing through the tip portion.

A further example method of deploying a prosthetic valve disclosed herein comprises inserting an introducer sheath into a blood vessel, inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein. The delivery sheath comprises a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member and a tip portion provided at the distal end of the sheath member. The tip portion has a central lumen extending therethrough. The tip portion is discontinuous and has two flaps extending circumferentially around the tip portion. The tip portion is movable between an expanded and an unexpanded configuration. In the unexpanded configuration, the tip portion defines a constant diameter along its length. In the expanded configuration, the tip portion flares open increasing a diameter of the distal end of the tip portion and increasing the spacing between the two flaps. The prosthetic valve is advanced through the distal end of the sheath member, to the tip portion, through the tip portion beyond a distal end of the delivery sheath to a treatment site such that the prosthetic valve at least partially expands within the tip portion and the tip portion moved from the unexpanded to the expanded configuration in response to the outward directed radial force of the prosthetic heart valve passing through the tip portion.

The invention relates to a delivery sheath system as illustrated on <FIG>.

Referring first to <FIG>, there is shown a prosthetic aortic heart valve <NUM>, according to one implementation. The prosthetic valve <NUM> includes an expandable frame member, or stent, <NUM> that supports a flexible leaflet section <NUM>. The prosthetic valve <NUM> is radially compressible to a compressed state for delivery through the body to a deployment site and expandable to its functional size shown in <FIG> at the deployment site. In certain implementations, the prosthetic valve <NUM> is self-expanding; that is, the prosthetic valve can radially expand to its functional size when advanced from the distal end of a delivery sheath. Apparatuses particularly suited for percutaneous delivery and implantation of a self-expanding prosthetic valve are described in detail below. In other implementations, the prosthetic valve can be a balloon-expandable prosthetic valve that can be adapted to be mounted in a compressed state on the balloon of a delivery catheter. The prosthetic valve can be expanded to its functional size at a deployment site by inflating the balloon, as known in the art. Example valves are described, for example, in <CIT>.

The illustrated prosthetic valve <NUM> is adapted to be deployed in the native aortic annulus, although it also can be used to replace the other native valves of the heart. Moreover, the prosthetic valve <NUM> can be adapted to replace other valves within the body, such venous valves.

<FIG> show the stent <NUM> without the leaflet section <NUM> for purposes of illustration. As shown, the stent <NUM> can be formed from a plurality of longitudinally extending, generally sinusoidal shaped frame members, or struts, <NUM>. The struts <NUM> are formed with alternating bends and are welded or otherwise secured to each other at nodes <NUM> formed from the vertices of adjacent bends so as to form a mesh structure. The struts <NUM> can be made of a suitable shape memory material, such as the nickel titanium alloy known as Nitinol, that allows the prosthetic valve to be compressed to a reduced diameter for delivery in a delivery apparatus (such as described below) and then causes the prosthetic valve to expand to its functional size inside the patient's body when deployed from the delivery apparatus. If the prosthetic valve is a balloon-expandable prosthetic valve that is adapted to be crimped onto an inflatable balloon of a delivery apparatus and expanded to its functional size by inflation of the balloon, the stent <NUM> can be made of a suitable ductile material, such as stainless steel.

The stent <NUM> has an inflow end <NUM> and an outflow end <NUM>. The mesh structure formed by struts <NUM> comprises a generally cylindrical "upper" or outflow end portion <NUM>, an outwardly bowed or distended intermediate section <NUM>, and an inwardly bowed "lower" or inflow end portion <NUM>. The intermediate section <NUM> desirably is sized and shaped to extend into the Valsalva sinuses in the root of the aorta to assist in anchoring the prosthetic valve in place once implanted. As shown, the mesh structure desirably has a curved shape along its entire length that gradually increases in diameter from the outflow end portion <NUM> to the intermediate section <NUM>, then gradually decreases in diameter from the intermediate section <NUM> to a location on the inflow end portion <NUM>, and then gradually increases in diameter to form a flared portion terminating at the inflow end <NUM>.

When the prosthetic valve is in its expanded state, the intermediate section <NUM> has a diameter D<NUM>, the inflow end portion <NUM> has a minimum diameter D<NUM>, the inflow end <NUM> has a diameter D<NUM>, and the outflow end portion <NUM> has a diameter D<NUM>, where D<NUM> is less than D<NUM>and D<NUM>, and D<NUM> is less than D<NUM>. In addition, D<NUM> and D<NUM> desirably are greater than the diameter of the native annulus in which the prosthetic valve is to be implanted. In this manner, the overall shape of the stent <NUM> assists in retaining the prosthetic valve at the implantation site. More specifically, and referring to <FIG>, the prosthetic valve <NUM> can be implanted within a native valve (the aortic valve in the illustrated example) such that the lower section <NUM> is positioned within the aortic annulus <NUM>, the intermediate section <NUM> extends above the aortic annulus into the Valsalva's sinuses <NUM>, and the lower flared end <NUM> extends below the aortic annulus. The prosthetic valve <NUM> is retained within the native valve by the radial outward force of the lower section <NUM> against the surrounding tissue of the aortic annulus <NUM> as well as the geometry of the stent. Specifically, the intermediate section <NUM> and the flared lower end <NUM> extend radially outwardly beyond the aortic annulus <NUM> to better resist against axial dislodgement of the prosthetic valve in the upstream and downstream directions (toward and away from the aorta). Depending on the condition of the native leaflets <NUM>, the prosthetic valve typically is deployed within the native annulus <NUM> with the native leaflets <NUM> folded upwardly and compressed between the outer surface of the stent <NUM> and the walls of the Valsalva sinuses, as depicted in <FIG>. In some cases, it may be desirable to excise the leaflets <NUM> prior to implanting the prosthetic valve <NUM>.

Known prosthetic valves having a self-expanding frame typically have additional anchoring devices or frame portions that extend into and become fixed to non-diseased areas of the vasculature. Because the shape of the stent <NUM> assists in retaining the prosthetic valve, additional anchoring devices are not required and the overall length L of the stent can be minimized to prevent the stent upper portion <NUM> from extending into the non-diseased area of the aorta, or to at least minimize the extent to which the upper portion <NUM> extends into the non-diseased area of the aorta. Avoiding the non-diseased area of the patient's vasculature helps avoid complications if future intervention is required. For example, the prosthetic valve can be more easily removed from the patient because the stent is primarily anchored to the diseased part of the native valve. Furthermore, a shorter prosthetic valve is more easily navigated around the aortic arch.

In particular implementations, for a prosthetic valve intended for use in a <NUM>-mm to <NUM>-mm annulus, the diameter D<NUM> is about <NUM> to about <NUM>, with <NUM> being a specific example; the diameter D<NUM> is about <NUM> to about <NUM>, with <NUM> being a specific example; the diameter D<NUM> is about <NUM> to about <NUM>, with <NUM> being a specific example; and the diameter D<NUM> is about <NUM> to about <NUM>, with <NUM> being a specific example. The length L in particular implementations is about <NUM> to about <NUM>, with <NUM> being a specific example.

Referring to <FIG>, the stent <NUM> can have a plurality of angularly spaced retaining arms, or projections, in the form of posts <NUM> (three in the illustrated implementation) that extend from the stent upper portion <NUM>. Each retaining arm <NUM> has a respective aperture <NUM> that is sized to receive prongs of a valve-retaining mechanism that can be used to form a releasable connection between the prosthetic valve and a delivery apparatus (described below). In alternative implementations, the retaining arms <NUM> need not be provided if a valve-retaining mechanism is not used.

As best shown in <FIG>, the leaflet assembly <NUM> in the illustrated implementation comprises three leaflets 34a, 34b, 34c made of a flexible material. Each leaflet has an inflow end portion <NUM> and an outflow end portion <NUM>. The leaflets can comprise any suitable biological material (e.g., pericardial tissue, such as bovine or equine pericadium), bio-compatible synthetic materials, or other such materials, such as those described in <CIT>. The leaflet assembly <NUM> can include an annular reinforcing skirt <NUM> that is secured to the outer surfaces of the inflow end portions of the leaflets 34a, 34b, 34c at a suture line <NUM> adjacent the inflow end of the prosthetic valve. The inflow end portion of the leaflet assembly <NUM> can be secured to the stent <NUM> by suturing the skirt <NUM> to struts <NUM> of the lower section <NUM> of the stent (best shown in <FIG>). As shown in <FIG>, the leaflet assembly <NUM> can further include an inner reinforcing strip <NUM> that is secured to the inner surfaces of the inflow end portions <NUM> of the leaflets.

Referring to <FIG>, the outflow end portion of the leaflet assembly <NUM> can be secured to the upper portion of the stent <NUM> at three angularly spaced commissure attachments of the leaflets 34a, 34b, 34c. As best shown in <FIG>, each commissure attachment can be formed by wrapping a reinforcing section <NUM> around adjacent upper edge portions <NUM> of a pair of leaflets at the commissure formed by the two leaflets and securing the reinforcing section <NUM> to the edge portions <NUM> with sutures <NUM>. The sandwiched layers of the reinforcing material and leaflets can then be secured to the struts <NUM> of the stent <NUM> with sutures <NUM> adjacent the outflow end of the stent. The leaflets therefore desirably extend the entire length or substantially the entire length of the stent from the inflow end <NUM> to the outflow end <NUM>. The reinforcing sections <NUM> reinforces the attachment of the leaflets to the stent so as to minimize stress concentrations at the suture lines and avoid "needle holes" on the portions of the leaflets that flex during use. The reinforcing sections <NUM>, the skirt <NUM>, and the inner reinforcing strip <NUM> desirably are made of a bio-compatible synthetic material, such as polytetrafluoroethylene (PTFE), or a woven fabric material, such as woven polyester (e.g., polyethylene terephtalate) (PET)).

<FIG> shows the operation of the prosthetic valve <NUM>. During diastole, the leaflets 34a, 34b, 34c collapse to effectively close the prosthetic valve. As shown, the curved shape of the intermediate section <NUM> of the stent <NUM> defines a space between the intermediate section and the leaflets that mimics the Valsalva sinuses. Thus, when the leaflets close, backflow entering the "sinuses" creates a turbulent flow of blood along the upper surfaces of the leaflets, as indicated by arrows <NUM>. This turbulence assists in washing the leaflets and the skirt <NUM> to minimize clot formation.

The prosthetic valve <NUM> can be implanted in a retrograde approach where the prosthetic valve, mounted in a crimped state at the distal end of a delivery apparatus, is introduced into the body via the femoral artery and advanced through the aortic arch to the heart, as further described in <CIT>.

<FIG> show a delivery apparatus <NUM>, according to one implementation, that can be used to deliver a self-expanding prosthetic valve, such as prosthetic valve <NUM> described above, through a patient's vasculature. Another implementation of a delivery apparatus is described in <CIT>,<CIT>,<CIT>.

The delivery apparatus <NUM> comprises a first, outermost or main catheter <NUM> (shown alone in <FIG>) having an elongated shaft <NUM>, the distal end of which is coupled to a delivery sheath <NUM> (<FIG>; also referred to as a delivery cylinder). The proximal end of the main catheter <NUM> is connected to a handle of the delivery apparatus. The handle mechanism can include an electric motor for operating the delivery apparatus. During delivery of a prosthetic valve, the handle can be used by a surgeon to advance and retract the delivery apparatus through the patient's vasculature. Although not required, the main catheter <NUM> can comprise a guide catheter that is configured to allow a surgeon to guide or control the amount the bending or flexing of a distal portion of the shaft <NUM> as it is advanced through the patient's vasculature, such as further described below. Another implementation of a guide catheter is disclosed in <CIT>.

As shown in <FIG>, the delivery apparatus <NUM> also includes a second, intermediate catheter <NUM> (also referred to herein as a torque shaft catheter) having an elongated shaft <NUM> (also referred to herein as a torque shaft) and an elongated screw <NUM> connected to the distal end of the shaft <NUM>. The shaft <NUM> of the intermediate catheter <NUM> extends coaxially through the shaft <NUM> of the main catheter <NUM>. The delivery apparatus <NUM> can also include a third, nose-cone catheter <NUM> having an elongated shaft <NUM> and a nose piece, or nose cone, <NUM> secured to the distal end portion of the shaft <NUM>. The nose piece <NUM> can have a tapered outer surface as shown for atraumatic tracking through the patient's vasculature. The shaft <NUM> of the nose-cone catheter extends through the prosthetic valve <NUM> (not shown in <FIG>) and the shaft <NUM> of the intermediate catheter <NUM>. In the illustrated configuration, the innermost shaft <NUM> is configured to be moveable axially and rotatably relative to the shafts <NUM>, <NUM>, and the torque shaft <NUM> is configured to be rotatable relative to the shafts <NUM>, <NUM> to effect valve deployment and release of the prosthetic valve from the delivery apparatus. For example, the torque shaft <NUM> is desirably configured to be rotatable relative to the delivery sheath <NUM> to effect incremental and controlled advancement of the prosthetic valve <NUM> from the delivery sheath <NUM>.

Additionally, the innermost shaft <NUM> can have a lumen for receiving a guide wire so that the delivery apparatus can be advanced over the guide wire inside the patient's vasculature.

As best shown in <FIG>, the outer catheter <NUM> can comprise a flex control mechanism <NUM> at a proximal end thereof to control the amount the bending or flexing of a distal portion of the outer shaft <NUM> as it is advanced through the patient's vasculature. For example, in some implementations, the flex control mechanism <NUM> can comprise a rotatable housing, or handle portion, <NUM> where rotating the housing in a first direction (e.g., clockwise), causes the distal end of the delivery apparatus to bend or flex. Rotating the housing in a second direction (e.g., counterclockwise), which relieves tension on the flex control mechanism <NUM> and allows the distal end of the delivery apparatus to flex back to its pre-flexed configuration under its own resiliency. The outer shaft <NUM> can comprise a proximal segment <NUM> that extends from the flex control mechanism <NUM> and a distal segment <NUM> that comprises a slotted metal tube that increases the flexibility of the outer shaft at this location. In the illustrated implementation, the proximal segment <NUM> extends from the flex control mechanism <NUM> to the distal segment <NUM> and therefore makes up the majority of the length of the outer shaft <NUM>. In alternative implementations, the entire length or substantially the entire length of the outer shaft <NUM> can be formed from a slotted metal tube comprising one or more sections of interconnected links <NUM>. In any case, the use of a main shaft having such a construction can allow the delivery apparatus to be highly steerable.

The distal end portion of the distal segment <NUM> of the outer catheter <NUM> can comprises an outer fork <NUM> of a valve-retaining mechanism <NUM> that is configured to releasably secure a prosthetic valve <NUM> to the delivery apparatus <NUM> during valve delivery, as described in detail below.

As illustrated in <FIG> and <FIG>, the sheath <NUM> extends over the prosthetic valve <NUM> and retains the prosthetic valve in a radially compressed state until the sheath <NUM> is retracted by the user to deploy the prosthetic valve. As described in <CIT>, the rotation of the torque shaft <NUM> (and thus the screw <NUM>) causes the axial movement of the sheath <NUM> relative to the valve-retaining mechanism. Rotation of the torque shaft <NUM> in a first direction causes the sheath <NUM> to move in the proximal direction, thereby deploying the prosthetic valve from the sheath <NUM>. Rotation of the torque shaft <NUM> to effect axial movement of the sheath <NUM> can be accomplished with a motorized mechanism or by manually turning a crank or wheel.

As illustrated in <FIG> and <FIG>, the sheath <NUM> can include a tip portion <NUM> provided at the distal end of the sheath <NUM>. The tip portion <NUM> can define a generally cylindrical structure having a central lumen co-axial with the central lumen of the sheath <NUM>. As will be described in more detail below, the tip portion <NUM> includes alternating portions of concave and convex curvature <NUM>, <NUM> that extend (at least partially) longitudinally along the tip portion <NUM>. The concave and convex portions <NUM>, <NUM> facilitate retrieval and folding of the prosthetic valve <NUM> as it is withdrawn through the opening at the distal end of the tip portion <NUM> and into the sheath <NUM>. In particular, the concave and convex portions <NUM>, <NUM> are defined such that at least one cross-sectional segment of an inner surface <NUM> of the tip portion includes alternating portions of concave and convex curvature <NUM>, <NUM> (where the concave or convex curvature is defined with respect to the longitudinal axis of the sheath <NUM>). The concave and convex portions <NUM>, <NUM> define a surface having a decreasing taper from the distal end of the tip portion <NUM> towards the sheath <NUM>.

<FIG> provides a side view of the delivery sheath <NUM> and tip portion <NUM> and <FIG> provides a cross-section view of the sheath <NUM> and tip portion <NUM> of <FIG> along section line A-A. As illustrated in <FIG>, diameter of the inner surface <NUM> at the distal end of the tip portion <NUM> is greater than the diameter of the inner surface <NUM> at the proximal end of the tip portion <NUM> creating a decreasing tapered surface extending between the distal and proximal ends of the tip portion <NUM>. The tapered inner surface <NUM> of the tip portion <NUM>, including the concave and convex portions <NUM>, <NUM>, folds or crimps the heart valve <NUM> as it is withdrawn into the sheath <NUM> and counteracting the outward radial force of the self-expanding heart valve <NUM>, reducing the amount of force necessary to withdraw the valve (fully or partially) into the sheath <NUM>. It is contemplated that the diameter of the inner surface <NUM> at the proximal end of the tip portion is at least <NUM>% less than the diameter of the inner surface <NUM> at the distal end of the tip portion. In another example, the dimeter of the inner surface <NUM> at the proximal end of the tip portion is at least <NUM>% less than the diameter of the inner surface <NUM> at the distal end of the tip portion. In a further example, the dimeter of the inner surface <NUM> at the proximal end of the tip portion is at least <NUM>% less than the diameter of the inner surface <NUM> at the distal end of the tip portion. In yet a further example, the dimeter of the inner surface <NUM> at the proximal end of the tip portion is at least <NUM>% less than the diameter of the inner surface <NUM> at the distal end of the tip portion. In another example, the dimeter of the inner surface <NUM> at the proximal end of the tip portion is no more than <NUM>% less than the diameter of the inner surface <NUM> at the distal end of the tip portion.

As illustrated in <FIG>, the diameter of the inner surface <NUM> of the tip portion <NUM> corresponds to the diameter of the inner surface of the sheath <NUM>, ensuring the smooth transition of the heart valve <NUM> through the central lumen of the tip portion <NUM> to the into the sheath <NUM>. It is also contemplated that a wall thickness of at least the proximal end of the tip portion <NUM> will correspond to the wall thickness of the sheath <NUM>.

<FIG> is a cross-section view of the tip portion <NUM> along section lines B-B (<FIG>). As provided in <FIG>, the alternating concave and convex portions <NUM>, <NUM> are formed symmetrically about the circumference of the tip portion <NUM>. The alternating concave and convex portions <NUM>, <NUM> are also distributed or spaced evenly about the circumference of the tip portion <NUM>. It is contemplated that the tip portion <NUM> will have at least at least two portions of concave curvature <NUM> and at least two portions of convex curvature <NUM>. While <FIG> illustrates a tip portion <NUM> having three segments of concave curvature <NUM> and three segments of convex curvature <NUM>, it is contemplated that the tip portion will include no more than eight portions of concave curvature and no more than eight portions of convex curvature.

The radius of curvature of each of the concave and convex portions <NUM>, <NUM> can be equal or vary around the circumference of the tip portion <NUM>. For example, each of the concave and convex portions <NUM>, <NUM> can have the same radius of curvature. Likewise, the radius of curvature of each of the concave and convex portions <NUM>, <NUM> can vary around the circumference of the tip portion <NUM>. In another example, each of the concave portions <NUM> may have the same radius of curvature, while each of the convex portions <NUM> may have the same radius of curvature (but different from the concave radius of curvature). In another example, various combination of the concave and convex portions <NUM>, <NUM> have the same radius of curvature. It is also contemplated that each of the concave and convex portions <NUM>, <NUM> may be equal or varying arc length, the arc length measured along the inner surface <NUM> of the tip portion <NUM> and defined as the portion of the concave or convex portions <NUM>, <NUM> having a uniform radius of curvature. For example, each of the concave and convex portions <NUM>, <NUM> can have the same arc length. Likewise, the arc length of each of the concave and convex portions <NUM>, <NUM> can vary around the circumference of the tip portion <NUM>. In another example, each of the concave portions <NUM> may have the same arc length, while each of the convex portions <NUM> may have the same arc length (that is different from the concave portions' arc length). In another example, various combination of the concave and convex portions <NUM>, <NUM> have the same arc length.

<FIG> provide distal and proximal end views of the tip portion <NUM> and the sheath <NUM>. As illustrated in <FIG>, the apex (e.g., 204a) of the convex portions <NUM> defines the minimum radius of the inner surface <NUM> of the tip portion <NUM>. That is, the apex 204a of at least one of the convex portions <NUM> defines the inner most surface of the tip portion with respect to the longitudinal axis <NUM> of the tip portion <NUM>. For example, the apex 204a of at least one of the convex portions <NUM> adjacent the proximal end of the tip portion <NUM> defines the minimum radius of the inner surface <NUM> of the tip portion <NUM>, as illustrated, for example in <FIG>. In some examples, the tip portion <NUM> includes a cylindrically-shaped segment extending between the proximal end of the tip portion <NUM> and the longitudinal end of the concave and convex portions <NUM>, <NUM>. In this example, the minimum radius defined by the apex 204a of the convex portions <NUM> corresponds to the radius of a cylindrically-shaped segment of the tip portion <NUM> (i.e., the portion adjacent the sheath <NUM>), as illustrate, for example in <FIG>.

Similarly, the apex (e.g., 202a) of the concave portions <NUM> defines the maximum radius of the inner surface <NUM> of the tip portion <NUM>. That is, the apex 202a of at least one of the concave portions <NUM> defines the outermost surface of the tip portion <NUM> with respect to the longitudinal axis <NUM>. For example, the apex 202a of at least one of the concave portions <NUM> adjacent a distal end of the tip portion <NUM> defines the maximum radius of the inner surface <NUM> of the tip portion <NUM>, as illustrated, for example, in <FIG>.

As illustrated in <FIG>, the outer surface <NUM> of the tip portion <NUM> includes alternating portions of concave and convex curvature. The alternating portions of concave and convex curvature of the outer surface <NUM> are aligned (e.g., circumferentially and/or radially aligned) with the alternating portions of concave and convex curvature of the inner surface <NUM>. Likewise, the alternating portions of concave and convex curvature of the outer surface <NUM> may have a radius of curvature and/or arc length corresponding or varying from the alternating concave and convex portions <NUM>, <NUM> of the inner surface <NUM>. It is contemplated that the outer surface <NUM> of the tip portion <NUM> defines a conically-shaped outer surface while maintaining the alternating concave and convex portions <NUM>, <NUM> of the inner surface <NUM>. It is further contemplated that the outer surface <NUM> of the tip portion <NUM> may define a cylindrically-shaped outer surface while maintaining the alternating concave and convex portions <NUM>, <NUM> of the inner surface <NUM>.

As illustrated in <FIG> and <FIG>, the tip portion <NUM> has uniform thickness both circumferentially and longitudinally. However, it is contemplated that various portions of the tip portion <NUM>, e.g., the portion including the concave and convex portions <NUM>, <NUM> may have varying circumferential and/or longitudinal thickness. The tip portion <NUM> can be formed from the same or different material as the sheath <NUM>. In some examples, the tip portion <NUM> is formed from a semirigid polymer such as nylon. In this example, the semirigid polymer is nor more than <NUM>% volumetrically expandable. The tip portion <NUM> can be formed integrally with the sheath <NUM> or coupled to the sheath <NUM> using any chemical and/or mechanical fastener known in the art. Alternatively, the tip portion <NUM> can be construction from a polymeric material that is reflowed or molded to the distal end portion of the sheath <NUM>.

<FIG> shows an enlarged view of the nose cone <NUM> secured to the distal end of the innermost shaft <NUM>. The nose cone <NUM> in the illustrated implementation includes a proximal end portion <NUM> that is sized to fit inside the tip portion <NUM> and the distal end of the sheath <NUM>. An intermediate section <NUM> of the nose cone is positioned immediately adjacent the end of the tip portion <NUM> in use and is formed with a plurality of concave and convex portions <NUM> corresponding to the tip portion <NUM>. The diameter of the intermediate section <NUM> at its proximal end <NUM> desirably is slightly larger than the outer diameter of the tip portion <NUM>. The proximal end <NUM> can be held in close contact with the distal end of the tip portion <NUM> to protect surrounding tissue from coming into contact with the distal edge of the sheath/tip portion <NUM>. The concave and convex portions of the nose cone <NUM> allow the intermediate section <NUM> to be compressed radially as the delivery apparatus is advanced through an introducer sheath. This allows the nose cone to be slightly oversized relative to the inner diameter of the introducer sheath. <FIG> shows a cross-section of the nose cone <NUM> and <FIG> shows a cross-section of the nose cone <NUM> and the sheath <NUM> in a delivery position with the prosthetic valve <NUM> retained in a compressed delivery state inside the sheath <NUM> (for purposes of illustration, only the stent <NUM> of the prosthetic valve is shown). As shown, the proximal end <NUM> of the intermediate section <NUM> can abut the distal end of the sheath <NUM> and a tapered proximal surface <NUM> of the nose cone can extend within a distal portion of the stent <NUM>.

As noted above, the delivery apparatus <NUM> can include a valve-retaining mechanism <NUM> (<FIG>) for releasably retaining a stent <NUM> of a prosthetic valve. The valve-retaining mechanism <NUM> can include a first valve-securement component in the form of an outer fork <NUM> (as best shown in <FIG>) (also referred to as an "outer trident" or "release trident"), and a second valve-securement component in the form of an inner fork <NUM> (as best shown in <FIG>) (also referred to as an "inner trident" or "locking trident"). The outer fork <NUM> cooperates with the inner fork <NUM> to form a releasable connection with the retaining arms <NUM> of the stent <NUM>.

The proximal end of the outer fork <NUM> is connected to the distal segment <NUM> of the outer shaft <NUM> and the distal end of the outer fork is releasably connected to the stent <NUM>. In the illustrated implementation, the outer fork <NUM> and the distal segment <NUM> can be integrally formed as a single component (e.g., the outer fork and the distal segment can be laser cut or otherwise machined from a single piece of metal tubing), although these components can be separately formed and subsequently connected to each other. The inner fork <NUM> can be mounted on the nose catheter shaft <NUM> (as best shown in <FIG>). The inner fork <NUM> connects the stent to the distal end portion of the nose catheter shaft <NUM>. The nose catheter shaft <NUM> can be moved axially relative to the outer shaft <NUM> to release the prosthetic valve from the valve-retaining mechanism, as further described below.

As best shown in <FIG>, the outer fork <NUM> includes a plurality of angularly-spaced prongs <NUM> (three in the illustrated implementation) corresponding to the retaining arms <NUM> of the stent <NUM>, which prongs extend from the distal end of distal segment <NUM>. The distal end portion of each prong <NUM> includes a respective opening <NUM>. As shown in <FIG>, the inner fork <NUM> includes a plurality of angularly-spaced prongs <NUM> (three in the illustrated implementation) corresponding to the retaining arms <NUM> of the stent <NUM>, which prongs extend from a base portion <NUM> at the proximal end of the inner fork. The base portion <NUM> of the inner fork is fixedly secured to the nose catheter shaft <NUM> (e.g., with a suitable adhesive) to prevent axial and rotational movement of the inner fork relative to the nose catheter shaft <NUM>.

Each prong of the outer fork cooperates with a corresponding prong of the inner fork to form a releasable connection with a retaining arm <NUM> of the stent. In the illustrated implementation, for example, the distal end portion of each prong <NUM> is formed with an opening <NUM>. When the prosthetic valve is secured to the delivery apparatus (as best shown in <FIG>), each retaining arm <NUM> of the stent <NUM> extends inwardly through an opening <NUM> of a prong <NUM> of the outer fork and a prong <NUM> of the inner fork is inserted through the opening <NUM> of the retaining arm <NUM> so as to retain the retaining arm <NUM> from backing out of the opening <NUM>. Retracting the inner prongs <NUM> proximally (in the direction of arrow <NUM> in <FIG>) to remove the prongs from the openings <NUM> is effective to release the prosthetic valve <NUM> from the retaining mechanism. When the inner fork <NUM> is moved to a proximal position (<FIG>), the retaining arms <NUM> of the stent can move radially outwardly from the openings <NUM> in the outer fork <NUM> under the resiliency of the stent. In this manner, the valve-retaining mechanism <NUM> forms a releasable connection with the prosthetic valve that is secure enough to retain the prosthetic valve relative to the delivery apparatus to allow the user to fine tune or adjust the position of the prosthetic valve after it is deployed from the delivery sheath. When the prosthetic valve is positioned at the desired implantation site, the connection between the prosthetic valve and the retaining mechanism can be released by retracting the nose catheter shaft <NUM> relative to the outer shaft <NUM> (which retracts the inner fork <NUM> relative to the outer fork <NUM>).

In an alternate implementation, the sheath <NUM> can include a tip portion <NUM> provided at the distal end of the sheath <NUM>. As illustrated in <FIG>, the tip portion <NUM> includes longitudinally extending folding regions <NUM> spaced around the circumference of the tip portion <NUM>. The folded regions <NUM> are movable between a folded configuration (<FIG>) and an unfolded configuration (<FIG>). In the unfolded configuration, the distal end of the tip portion <NUM> flares/expands defining an increasing tapered/conically shaped surface, with the larger diameter at the distal end of the tip portion <NUM>.

<FIG> is an enlarged perspective view of the distal end of the delivery sheath of <FIG> in the folded configuration. As described in more detail below, in the folded configuration, the tip portion <NUM> creases along several longitudinally extending edges such that circumferential portions of the tip portion <NUM> at least partially overlap. As illustrated in <FIG>, the tip portion <NUM> includes a single or a plurality of folding regions <NUM> circumferentially spaced around the tip portion <NUM>. The tip portion <NUM> can include at least two folded regions <NUM>. For example, the tip portion <NUM> can include six folding regions <NUM> spaced around its circumference. It is contemplated that the tip portion <NUM> can include six or more folding regions <NUM>. As provided in <FIG>, the folding regions <NUM> can be spaced at regular intervals around the circumference of the tip portion <NUM>. Alternatively, the folding regions <NUM> can be spaced at irregular intervals around the circumference of the tip portions <NUM>. Accordingly, the folding regions <NUM> can be symmetrically or asymmetrically spaced around a circumference of the tip portion <NUM>.

The structure of a first folding region <NUM> is defined by a first (outer) circumferential portion <NUM>, a first and second longitudinal edges <NUM>, <NUM>, and a second (intermediate) circumferential portion <NUM> extending between the first and second longitudinal edges <NUM>, <NUM>. The first folding region <NUM> is configured to crease at the first and second longitudinal edges <NUM>, <NUM> into the folded configuration such that the first and second circumferential portions <NUM>, <NUM> at least partially overlap. As illustrated in <FIG>, when folded, the second circumferential portion <NUM> is radially inward of the first circumferential portion <NUM>.

Similarly, the tip portion <NUM> can include a second folding region <NUM> defined by a third (outer) circumferential portion <NUM>, a third and fourth longitudinal edge <NUM>, <NUM>, and fourth (intermediate) circumferential portion <NUM> extending between the first and second longitudinal edge <NUM>, <NUM>. The second folding region <NUM> is configured to crease at the third and fourth longitudinal edges <NUM>, <NUM> into the folded configuration such that the third and fourth circumferential portions <NUM>, <NUM> at least partially overlap. As illustrated in <FIG>, when folded, the fourth circumferential portion <NUM> is radially inward of the third circumferential portion <NUM>.

As provided in <FIG>, the first and second folding regions <NUM>, <NUM> are spaced circumferentially around the tip portion <NUM> on opposing sides of a fifth (inner) circumferential portion <NUM>. The fifth circumferential region <NUM> extends between the second longitudinal edge <NUM> of the first folding region <NUM> and the third longitudinal edge <NUM> of the second folding region <NUM>. In the folded configuration, the fifth (inner) circumferential portion <NUM> is radially inward of the second and fourth (intermediate) circumferential portions <NUM>, <NUM> (and the first and third (outer) circumferential portions <NUM>, <NUM>). The width of the fifth circumferential portion <NUM>, measured around the circumference of the tip portion <NUM> (e.g., arc length), is less than the width of the first circumferential portion <NUM> and/or the third circumferential portion <NUM>. The width of either of the second and fourth circumferential portions <NUM>, <NUM> is less than the width of the fifth circumferential portion <NUM>.

As provided in <FIG> and <FIG>, additional similarly structured folding regions <NUM> are spaced uniformly around the circumference of the tip portion <NUM>. When the sheath is in the unfolded configuration, the various circumferential portions extend around the circumference of the tip portion <NUM> and the longitudinal edges flatten out and unfold/uncrease, defining a continuous outer perimeter of the distal end of the tip portion <NUM>.

As will be described in more details below, in some implementations, the folding regions <NUM> can be biased in the folded configuration such that when there is no load applied to the inner surface of the tip portion <NUM> (e.g., the outward directed radial force of a passing implant), the tip portion <NUM> returns to the folded configuration. It is also contemplated that an outer jacket or elastomeric layer can be provided over the outer surface of the tip portion <NUM> to bias the folding regions <NUM> to return to the folded configuration.

In general, in both the folded and unfolded configurations, the tip portion <NUM> defines a continuous tubular structure having a central lumen extending therethrough. The diameter of the tip portion <NUM> in the folded configuration corresponds to a diameter of the ring portion <NUM> (described in more detail below). The diameter of the tip portion <NUM> in the unfolded configuration is greater than the diameter of the ring portion <NUM>. The tip portion <NUM> and the ring portion <NUM> form a continuous central lumen extending between a proximal end of the ring portion <NUM> and a distal end of the tip portion <NUM>. The inner diameter of the central lumen of the tip portion <NUM> corresponds to the inner diameter of the central lumen of the ring portion <NUM>.

When folded, the tip portion <NUM> forms a cylindrical tubular structure, with the folding portions <NUM> formed therein, e.g., heat set. In the unfolded configuration, the tip portion <NUM> defines conically-shaped inner and outer surfaces. As illustrated in <FIG>, at least a portion of the tip portion <NUM> (i.e., the portion adjacent the proximal end of the tip portion <NUM> abutting the ring portion <NUM>) includes a cylindrically-shaped inner and outer surface.

It is contemplated that the tip portion <NUM> can have a thickness corresponding to the thickness of the ring portion <NUM>. Alternatively, the thickness of the tip portion <NUM> is less than the thickness of the ring portion <NUM>. It is further contemplated that the tip portion <NUM> has a uniform thickness along its length. Alternatively, the tip portion <NUM> has a non-uniform/varying thickness along its length. Similarly, the tip portion <NUM> has a uniform thickness around its circumference.

As described above, the tip portion <NUM> expands from the folded to the unfolded configuration in response to the outward directed radial force of a passing implant/medical device. To facilitate expansion/unfolding, the tip portion <NUM> can have an elastic modulus less than the elastic modulus of the ring portion <NUM>. Alternatively, the tip portion <NUM> has an elastic modulus corresponding to the elastic modulus of the ring portion <NUM>.

As illustrated in <FIG>, a ring (holding) portion <NUM> can be provided between the distal end of the sheath <NUM> and the proximal end of the tip portion <NUM>. The ring portion <NUM> can maintain the heart valve/implant in a compressed configuration before passing to the tip portion <NUM>. The ring portion <NUM> defines an elongated tubular structure having a central lumen extending therethrough such that the ring portion <NUM> defines cylindrically-shaped inner and outer surfaces. The ring portion <NUM> and the sheath member <NUM> form a continuous central lumen extending between the proximal end of the sheath member <NUM> and a distal end of the ring portion <NUM>/tip portion <NUM>. In general, the inner diameter of the central lumen extending through the ring portion <NUM> corresponds to/is the same as the inner diameter of a central lumen of the sheath member <NUM>. Similarly, the ring portion <NUM> and the sheath member <NUM> can have the same thickness (e.g., wall thickness measured radially between the inner and outer surface of the ring portion <NUM>/sheath member <NUM>). Alternatively, the ring portion <NUM> can have a wall thickness greater than the sheath member <NUM>. It is contemplated that the ring portion <NUM> has a uniform thickness along its length. Similarly, the ring portion <NUM> has a uniform thickness around its circumference.

As described above, the ring portion <NUM> can maintain the heart valve in a compressed configuration before passing into the tip portion <NUM>. In general, the elastic modulus of the ring portion <NUM> corresponds to or is greater than the elastic modulus of the sheath member. In another example, the ring portion <NUM> has an elastic modulus less than an elastic modulus of the sheath member <NUM>.

As illustrated in <FIG>, the length of the ring portion <NUM> corresponds to or is greater than the length of the tip portion <NUM>. For example, the length of the ring portion <NUM> is at least twice the length of the tip portion <NUM>. In another example, the length of the ring portion <NUM> is less than the length of the tip portion <NUM>. In general, the length of the ring portion <NUM> at least corresponds to the length of a compressed/crimped prosthetic heart valve.

The sheath member <NUM>, the ring portion <NUM>, and the tip portion <NUM> can be constructed from the same or different material. The ring portion <NUM> can be formed as a separate structure and coupled to the distal end of the sheath member <NUM>. Similarly, the tip portion <NUM> can be formed as a separate structure and coupled to the distal end of the ring portion <NUM>. Alternatively, the ring portion <NUM> can be integrally formed with the sheath member <NUM> and/or the tip portion <NUM>.

When combined with a self-expandable prosthetic heart valve, the central lumens of both the sheath member <NUM> and the ring portion <NUM> are sized and configured to receive and maintain the prosthetic heart valve in a compressed configuration. The tip portion <NUM> moves from the folded to the unfolded configuration in response to the outward directed radial force of the prosthetic heart valve as it passes through the tip portion <NUM>. Movement from the folded configuration to the unfolded configuration causes the tip portion <NUM> to transition from an elongated cylindrical shape to a conical shape defining an increasing tapered inner surface, where the diameter of the distal end of the tip portion <NUM> is greater than the diameter of the proximal end of the tip portion <NUM>. The prosthetic heart valve can at least partially expand from a compressed configuration towards an expanded configuration as it passes through the tip portion <NUM>, and fully expand as it passes beyond the distal end of the tip portion <NUM>. The tip portion <NUM> can be biased towards the folded configuration such that the tip portion <NUM> moves back towards the folded configuration after the prosthetic heart valve passes through the tip portion <NUM>.

In another implementation, the sheath <NUM> can include a tip portion <NUM> provided at a distal end of the sheath <NUM>. As illustrated in <FIG>, the tip portion <NUM> includes flaps <NUM>/arms that flare open to provide a distal end of the sheath <NUM> having an increased diameter to accommodate passage of the implant/medical device.

When expanded the tip portion <NUM> is forms a discontinuous surface having two flaps <NUM> that extending circumferentially around the tip portion. The tip portion <NUM> is movable between an unexpanded (<FIG>) and an expanded configuration (<FIG>). In the unexpanded configuration, the tip portion <NUM> defines a constant diameter along its length. Whereas, in the expanded configuration, the tip portion <NUM> flares open increasing the diameter of the distal end of the tip portion <NUM> and increasing the spacing between the flaps <NUM>.

The flaps <NUM> can be formed symmetrically about the tip portion <NUM> such that the circumferential width of the various flaps correspond. For example, as illustrated in <FIG>, the sheath <NUM> can include three flaps having equal width and symmetrically spaced around the circumference of the tip portion <NUM>. Alternatively, the flaps <NUM> can be formed asymmetrically about the tip portion <NUM> such that the circumferential width of the flaps varies. As provided in <FIG>, the tip portion includes a first, second, and third flap <NUM>, <NUM>, <NUM>. In the unexpanded configuration, the first, second and third flaps <NUM>, <NUM>, <NUM> are formed around the tip portion <NUM> with a gap <NUM>, <NUM>, <NUM> provided between adjacent flaps. For example, each of the a first, second, and third flap <NUM>, <NUM>, <NUM> include a leading edge and a trailing edge, where in the unexpanded configuration the gap <NUM>, <NUM>, <NUM> is provided between adjacent leading and trailing side edges of each of the first, second and third flaps <NUM>, <NUM>, <NUM>. For example, the first flap <NUM> includes a leading edge <NUM> and a trailing edge <NUM>, the second flap <NUM> includes a leading edge <NUM> and a trailing edge <NUM>, and the third flap <NUM> includes a leading edge <NUM> and a trailing edge <NUM>. The first gap <NUM> is formed between the trailing edge <NUM> of the first flap <NUM> and the leading edge <NUM> of the second flap <NUM>. The second gap <NUM> is formed between the trailing edge <NUM> of the second flap <NUM> and the leading edge <NUM> of the third flap <NUM>. The third gap <NUM> is formed between the trailing edge <NUM> if of the third flap <NUM> and the leading edge <NUM> of the first flap <NUM>.

In some implementations, in the unexpanded configuration, the first, second and third flaps <NUM>, <NUM>, <NUM> are coupled to each other along weakened side edges (at the leading and trailing edges). The movement of the tip portion <NUM> from the unexpanded to the expanded configuration causes the first, second and third flaps <NUM>, <NUM>, <NUM> to separate along the weakened side edges to increase the spacing between adjacent flaps. An example weakened side edge is formed from a perforation, a thinned portion, a crease, or a combination thereof.

As will be described in more details below, in some implementations the flaps <NUM> can be biased in the unexpanded configuration such that when there is no load applied to the inner surface of the tip portion <NUM> (e.g., the outward directed radial force of a passing implant), the tip portion <NUM> returns to the unexpanded configuration. It is also contemplated that an outer jacket or elastomeric layer can be provided over the outer surface of the tip portion <NUM> to bias the flaps <NUM> to return to the unexpanded configuration.

Similar to the tip portion <NUM> depicted in <FIG>, the tip portion <NUM> is coupled to the distal end of the sheath member <NUM>, without an intermediary ring portion <NUM>. The diameter of the proximal end of the tip portion <NUM> corresponding to the diameter of a distal end of the sheath portion <NUM>. As depicted in <FIG>, the ring portion <NUM> is provided between the distal end of the sheath member <NUM> and a proximal end of the tip portion <NUM>. The diameter of the tip portion <NUM> in the unexpanded configuration corresponds to the diameter of at least one of the sheath member <NUM> and the ring portion <NUM>, and the diameter of the tip portion <NUM> in the expanded configuration is greater than the diameter of the sheath member and/or the ring portion <NUM>. The inner surface of the tip portion <NUM> at its proximal end defines a circular-shape in cross-section when the tip portion <NUM> is in an unexpanded configuration, i.e., the inner surface of the tip portion forms an elongated cylindrical shape when in the unexpanded configuration. The tip portion <NUM>, the ring portion <NUM> and the sheath member <NUM> form a continuous central lumen extending between a proximal end of the sheath member and a distal end of the tip portion. In general, the unexpanded inner diameter of the central lumen extending through the tip portion <NUM> corresponds/is the same as the inner diameter of a central lumen of the ring portion <NUM>. Similarly, the thickness of the tip portion <NUM> can corresponds to the thickness of the ring portion <NUM> and/or the sheath member <NUM>. Alternatively, the thickness of the tip portion <NUM> can be less than the thickness of the ring portion <NUM> and/or the sheath member <NUM>.

As described above, the tip portion <NUM> expands in response to the outward directed radial force of a passing implant/medical device. To facilitate expansion, tip portion <NUM> (flaps <NUM>) can have an elastic modulus less than the elastic modulus of the ring portion <NUM> and/or the sheath member <NUM>. For example, the tip portion <NUM> (flaps <NUM>) can be formed from a superelastic material. In some examples, the tip portion <NUM> (flaps <NUM>) is formed from a metal alloy. The metal alloy is covered with a plastic to facilitate expansion/contraction and provide a smooth less traumatic surface of the flaps with respect to patient anatomy.

It is contemplated that the tip portion <NUM> has a uniform thickness along its length. Similarly, the tip portion <NUM> has a uniform thickness around its circumference. As illustrated in <FIG>, the length of the tip portion <NUM> is less than a length of the ring portion <NUM>. In other implementations, not shown, the length of the tip portion <NUM> corresponds to or is greater than the length of the ring portion <NUM>.

Similar to the implementation depicted in <FIG>, the sheath <NUM> includes a ring (holding) portion <NUM> between the distal end of the sheath <NUM> and the proximal end of the tip portion <NUM>. The ring portion <NUM> maintains the heart valve in a compressed configuration before passing to the tip portion <NUM>. Unless otherwise noted, the ring portion <NUM> includes similar structure to the ring portion <NUM>.

The ring portion <NUM> can be formed as a separate structure and coupled to the distal end of the sheath member <NUM>. Similarly, the tip portion <NUM> can be formed as a separate structure and coupled to the distal end of the ring portion <NUM>. Alternatively, the ring portion <NUM> is integrally formed with the sheath member <NUM> and/or the tip portion <NUM>.

When combined with a self-expandable prosthetic heart valve, the central lumens of both the sheath member <NUM> and the ring portion <NUM> are sized and configured to receive and maintain the prosthetic heart valve in a compressed configuration. The tip portion <NUM> moves from the unexpanded to the expanded configuration in response to the outward directed radial force of the prosthetic heart valve as it passes through the tip portion <NUM>. Movement from the unexpanded configuration to the expanded configuration cause the flaps <NUM> to flare open such that the diameter of the distal end of the tip portion <NUM> is greater than a diameter of a proximal end of the tip portion <NUM>. The prosthetic heart valve can at least partially expand from a compressed configuration towards an expanded configuration as it passes through the tip portion <NUM>, and fully expand as it passes beyond the distal end of the tip portion <NUM>. The tip portion <NUM> is biased towards the unexpanded configuration such that the tip portion <NUM> moves back towards the unexpanded configuration after the prosthetic heart valve passes through the tip portion <NUM>.

Techniques for compressing and loading the prosthetic valve <NUM> into the sheath <NUM> are described below. Once the prosthetic valve <NUM> is loaded in the delivery sheath <NUM>, the delivery apparatus <NUM> can be inserted into the patient's body for delivery of the prosthetic valve. In one approach, the prosthetic valve can be delivered in a retrograde procedure where delivery apparatus is inserted into a femoral artery and advanced through the patient's vasculature to the heart. Prior to insertion of the delivery apparatus, an introducer sheath can be inserted into the femoral artery followed by a guide wire, which is advanced through the patient's vasculature through the aorta and into the left ventricle. The delivery apparatus <NUM> can then be inserted through the introducer sheath and advanced over the guide wire until the distal end portion of the delivery apparatus containing the prosthetic valve <NUM> is advanced to a location adjacent to or within the native aortic valve.

Thereafter, the prosthetic valve <NUM> can be deployed from the delivery apparatus <NUM> by rotating the torque shaft <NUM> relative to the outer shaft <NUM>. The proximal end of the torque shaft <NUM> can be operatively connected to a manually rotatable handle portion or a motorized mechanism that allows the surgeon to effect rotation of the torque shaft <NUM> relative to the outer shaft <NUM>. Rotation of the torque shaft <NUM> causes the sheath <NUM> to move in the proximal direction toward the outer shaft, which deploys the prosthetic valve from the sheath <NUM>. Rotation of the torque shaft <NUM> causes the sheath to move relative to the prosthetic valve in a precise and controlled manner as the prosthetic valve advances from the open distal end of the delivery sheath and begins to expand. Hence, unlike known delivery apparatuses, as the prosthetic valve begins to advance from the delivery sheath and expand, the prosthetic valve is held against uncontrolled movement from the sheath caused by the expansion force of the prosthetic valve against the distal end of the sheath. In addition, as the sheath <NUM> is retracted, the prosthetic valve <NUM> is retained in a stationary position relative to the ends of the inner shaft <NUM> and the outer shaft <NUM> by virtue of the valve-retaining mechanism <NUM>. As such, the prosthetic valve <NUM> can be held stationary relative to the target location in the body as the sheath is retracted. Moreover, after the prosthetic valve is partially advanced from the sheath, it may be desirable to retract the prosthetic valve back into the sheath, for example, to reposition the prosthetic valve or to withdraw the prosthetic valve entirely from the body. The partially deployed prosthetic valve can be retracted back into the sheath by reversing the rotation of the torque shaft, which causes the sheath <NUM> to advance back over the prosthetic valve in the distal direction.

The prosthetic valve <NUM> advances through the distal end of the delivery sheath <NUM> and through the tip portion <NUM>. The prosthetic valve <NUM> partially expands within the tip portion <NUM> as illustrated, for example, in <FIG>. Traditional methods of deploying a self-expanding valve utilize a cylindrically-shaped sheath. However, during deployment this structure can cause the valve to "jump" and spring open rapidly in the patient anatomy, causing damage to the valve and the trauma to the patient. In contrast, when using the sheath <NUM> and tip portion <NUM> illustrated in <FIG> and <FIG>, the tapered inner surface <NUM> and the concave and convex portions <NUM>, <NUM> of the present disclosure facilitate the controlled and directed expansion of the prosthetic valve <NUM>. For example, the increasing taper of the tip portion <NUM> provides for the controlled and gradual expansion of the prosthetic valve <NUM>. Likewise, the alternating concave and convex portions <NUM>, <NUM> provide for areas within the tip of increased diameter, directing the prosthetic valve <NUM> to expand first towards the concave portions <NUM>. By spacing the concave and convex portions <NUM>, <NUM> symmetrically around the tip portion <NUM> ensures the prosthetic valve expands uniformly around its circumference. The controlled expansion of the prosthetic valve <NUM> is illustrated, for example, in <FIG>.

After the prosthetic valve <NUM> is advanced through the tip portion <NUM> (and at least partially expands therein) and exits beyond the distal end of the tip portion/delivery sheath, the prosthetic valve <NUM> expands to its functional size. The prosthetic valve remains connected to the delivery apparatus via the retaining mechanism <NUM>. Consequently, after the prosthetic valve is advanced from the delivery sheath, the surgeon can reposition the prosthetic valve relative to the desired implantation position in the native valve such as by moving the delivery apparatus in the proximal and distal directions or side to side, or rotating the delivery apparatus, which causes corresponding movement of the prosthetic valve <NUM>. The retaining mechanism <NUM> desirably provides a connection between the prosthetic valve and the delivery apparatus that is secure and rigid enough to retain the position of the prosthetic valve relative to the delivery apparatus against the flow of the blood as the position of the prosthetic valve is adjusted relative to the desired implantation position in the native valve.

If it is necessary to retrieve the prosthetic valve <NUM> such as for removal or repositioning, the retaining mechanism <NUM> is drawn proximally and the prosthetic valve <NUM> is withdrawn (e.g., fully or partially) into the tip portion <NUM>. The alternating portions of concave and convex curvature <NUM>, <NUM> facilitate the directed compression (e.g., folding and/or crimping) of the prosthetic heart valve as it is withdrawn into the tip portion <NUM> and towards the sheath <NUM> (see e.g., <FIG>). <FIG> provides a schematic representation of the prosthetic valve <NUM> being drawn into the tip portion <NUM> and <FIG> provides a distal end view of the prosthetic valve <NUM> partially compressed within the tip portion <NUM>. As illustrated in <FIG>, the portions of concave and convex curvature <NUM>, <NUM> work in combination direct the uniform compression of the prosthetic valve <NUM>. As described above, while traditional strategies for deploying and re-sheathing a self-expanding prosthetic valve utilize a cylindrical sheath to contain and deploy the valve, the large radial forces of the valve can cause it to fold inwards on itself in non-uniform ways. As a result, the valve can fold and crumple inwards irregularly, and get stuck in the sheath or even be damaged to that it cannot be re-deployed. In contrast, the alternating concave and convex portions <NUM>, <NUM> provided in the present tip portion <NUM> creates several small arches rather than one large arch for a circular sheath. These smaller arches reduce the hoop stress in the valve, making it more stable and less likely to fold inwards. This is demonstrated in the circular arch stress equation: <MAT>, where R is the load at the base supports, w is the applied weight, L is the span or diameter of the arch. Assuming all variables other variables are equal, decreasing the inner cylinder diameter L will reduce the load on the arch R. As a result, the concave and convex curvature <NUM>, <NUM> work in combination to reduce the hoop stress on the valve and provide for uniform compression of the prosthetic valve <NUM>. Accordingly, as the prosthetic valve <NUM> is compressed in remains generally circular as it is compressed within the tip portion <NUM> and drawn into the sheath <NUM>. The concave and convex portions <NUM>, <NUM> prevent the irregular folding/crimping of the prosthetic valve <NUM> as it transitions between a fully/partially expanded configuration to a non/less expanded configuration.

Once the surgeon positions the prosthetic valve at the desired implantation position in the native valve, the connection between the prosthetic valve and the delivery apparatus can be released by retracting the innermost shaft <NUM> in the proximal direction relative to the outer shaft <NUM>, which is effective to retract the inner fork <NUM> to withdraw its prongs <NUM> from the openings <NUM> in the retaining arms <NUM> of the prosthetic valve (<FIG>). Slightly retracting of the outer shaft <NUM> allows the outer fork <NUM> to back off the retaining arms <NUM> of the prosthetic valve, which slide outwardly through openings <NUM> in the outer fork to completely disconnect the prosthetic valve from the retaining mechanism <NUM>. Thereafter, the delivery apparatus can be withdrawn from the body, leaving the prosthetic aortic valve <NUM> implanted within the native valve (such as shown in <FIG>).

In an alternative implementation, when the sheath <NUM> and tip portion <NUM> of <FIG> is used, the prosthetic valve <NUM> is advanced through the distal end of the sheath member <NUM> into the ring portion <NUM>. The prosthetic valve <NUM> is then advanced, in a compressed configuration, through the ring portion <NUM> into the tip portion <NUM>. The prosthetic valve <NUM> at least nartially exnands within the tip portion <NUM> and the tip portion <NUM> moves from the folded to the unfolded configuration in response to the outward directed radial force of the prosthetic heart valve <NUM> passing through the tip portion <NUM>. Advancing the prosthetic valve <NUM> through the tip portion <NUM> causes the first and second circumferential portions <NUM>, <NUM> of the first folding region <NUM> to move to a less overlapping position than when compared to the folded configuration. Further advancing prosthetic valve <NUM> through the tip portion <NUM> causes the first and second circumferential portions <NUM>, <NUM> to circumferentially align when the tip portion <NUM> is a fully unfolded configuration. The prosthetic valve <NUM> is then advanced beyond a distal end of the tip portion <NUM> to the treatment site. The tip portion <NUM> is biased towards a folded configuration such that the tip portion <NUM> returns toward the folded configuration after the prosthetic heart valve <NUM> has fully passed through the tip portion <NUM>.

Withdrawing the prosthetic valve <NUM> from the treatment site is accomplished by moving the prosthetic valve <NUM> in a direction towards the sheath member <NUM> such that the prosthetic valve <NUM> is withdrawn (e.g., fully or partially) into the tip portion <NUM>. The prosthetic valve <NUM> is disposed in an at least a partially expanded configuration when outside of the delivery sheath <NUM>/tip portion <NUM>. The tapered inner surface of the tip portion <NUM> facilitates the compression (e.g., folding and/or crimping) of the prosthetic heart valve <NUM> as it is withdrawn into the tip portion <NUM> and towards the sheath member <NUM>. When withdrawing the prosthetic valve <NUM> from the treatment site further, the prosthetic valve <NUM> is retained in the sheath member <NUM> and/or the ring portion <NUM>, the delivery sheath <NUM> removed from the blood vessel, and delivery sheath <NUM> from the introducer sheath.

In an alternative implementation, when the sheath <NUM> and tip portion <NUM> of <FIG> is used, the prosthetic valve <NUM> is advanced through the distal end of the sheath member <NUM> into the ring portion <NUM>. The prosthetic valve <NUM> is then advanced, in a compressed configuration, through the ring portion <NUM> into the tip portion <NUM>. The prosthetic valve <NUM> at least partially expands within the tip portion <NUM> and the tip portion <NUM> moves from the unexpanded to the expanded configuration in response to the outward directed radial force of the prosthetic heart valve <NUM> passing through the tip portion <NUM>, flaring open the tip portion <NUM> increasing a diameter of the distal end of the tip portion <NUM>. Advancing the prosthetic valve <NUM> through the tip portion <NUM> causes the gaps <NUM>, <NUM>, <NUM> between the adjacent flaps to increase, increasing the spacing between flaps <NUM>. In some implementations, in the unexpanded configuration, the flaps <NUM> are coupled to each other along weakened side edges. Advancing the prosthetic valve <NUM> through the tip portion <NUM> causes the flaps <NUM> to separate along the weakened side edges to increase the spacing between adjacent flaps <NUM>. The prosthetic valve <NUM> is then advanced beyond a distal end of the tip portion <NUM> to the treatment site. The tip portion <NUM> is biased towards the unexpanded configuration such that the tip portion <NUM> returns toward the unexpanded configuration after the prosthetic heart valve <NUM> has fully passed through the tip portion <NUM>.

In an alternative implementation, the delivery apparatus can be adapted to deliver a balloon-expandable prosthetic valve. As described above, the valve retaining mechanism <NUM> can be used to secure the prosthetic valve to the end of the delivery apparatus. Since the stent of the prosthetic valve is not self-expanding, the sheath <NUM> can be optional. The retaining mechanism <NUM> enhances the pushability of the delivery apparatus and prosthetic valve assembly through an introducer sheath.

The following description of certain examples of the inventive concepts should not be used to limit the scope of the claims. Other examples, features, aspects, implementations, and advantages will become apparent to those skilled in the art from the following description. As will be realized, the device and/or methods are capable of other different and obvious aspects.

For purposes of this description, certain aspects, advantages, and novel features of the implementations of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed implementations, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect, implementation or example of the invention are to be understood to be applicable to any other aspect, implementation or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises," means "including but not limited to," and is not intended to exclude, for example, other additives, components, integers or steps. "Exemplary" means "an example of" and is not intended to convey an indication of a preferred or ideal aspect. "Such as" is not used in a restrictive sense, but for explanatory purposes.

The terms "proximal" and "distal" as used herein refer to regions of a sheath, catheter, or delivery assembly. "Proximal" means that region closest to handle of the device, while "distal" means that region farthest away from the handle of the device.

The term "tube" or "tubular" as used herein is not meant to limit shapes to circular cross-sections. Instead, tube or tubular can refer to any elongate structure with a closed-cross section and lumen extending axially therethrough. A tube may also have some selectively located slits or openings therein - although it still will provide enough of a closed structure to contain other components within its lumen(s).

Beyond transcatheter heart valves, the expandable sheath <NUM> can be useful for other types of minimally invasive procedure, such as any procedure requiring introduction of an apparatus into a subject's vessel. For example, the expandable sheath <NUM> can be used to introduce other types of delivery apparatus for placing various types of intraluminal devices (e.g., stents, stented grafts, balloon catheters for angioplasty procedures, 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.).

Although the foregoing implementations of the present disclosure have been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the scope of the present disclosure. It should be recognized that the illustrated implementations are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Moreover, additional implementations are disclosed in <CIT> (<CIT>), and <CIT>, <CIT>, <CIT>. It is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed implementations described above, but should be determined only by a fair reading of the claims that follow.

A method of deploying a prosthetic valve comprising: inserting an introducer sheath into a blood vessel, inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein, the delivery sheath comprising: a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member; a tip portion provided at the distal end of the sheath member, the tip portion having a central lumen extending therethrough, wherein at least one cross-sectional segment of an inner surface of the tip portion includes alternating portions of concave and convex curvature; advancing a prosthetic valve through the distal end of the sheath member, to the tip portion; advancing the prosthetic valve through the tip portion to a treatment site such that the prosthetic valve at least partially expands within the tip portion, wherein the alternating portions of concave and convex curvature facilitate directed expansion of the prosthetic heart valve as it passes through the tip portion.

The method according to any example herein, wherein the delivery sheath further comprises, a nose cone, having a proximal end and a tapering distal end, the nose cone detachably coupled to the distal end of the tip portion; the method further comprising advancing the nose cone away from the distal end of the tip portion.

The method according to any example herein, further comprising withdrawing the prosthetic valve from the treatment site by moving the prosthetic valve in a direction towards the sheath member such that the prosthetic valve is withdrawn (e.g., fully or partially) into the tip portion, wherein the prosthetic valve is disposed in an at least a partially expanded configuration when outside of the delivery sheath, and wherein the alternating portions of concave and convex curvature facilitate directed compression (e.g., folding and/or crimping) of the prosthetic heart valve as it is withdrawn into the tip portion and towards the sheath member.

The method according to any example herein, wherein sections of the prosthetic valve are compressed at circumferential locations corresponding to the portions of convex curvature (e.g., compressed greater at the circumferential locations corresponding to the portions of convex curvature than compared to compression of the valve at those portions of concave curvature).

The method according to any example herein, wherein the prosthetic valve is a super elastic self-expanding valve.

The method according to any example herein, further comprising completely removing the prosthetic valve from the tip portion.

The method according to any example herein, further comprising retaining the prosthetic valve in the sheath member, removing the delivery sheath from the blood vessel, and removing the delivery sheath from the introducer sheath.

The method according to any example herein, wherein the prosthetic valve is an Aortic valve.

A method of deploying a prosthetic valve comprising: inserting an introducer sheath into a blood vessel; inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein, the delivery sheath comprising: a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member; a ring portion provided at the distal end of the sheath member; a tip portion extending from a distal end of the ring portion, the tip portion including a longitudinally extending folding region movable between a folded and unfolded configuration, in the folded configuration the tip portion creases along a longitudinally extending edge such that circumferential portions of the tip portion at least partially overlap, in the unfolded configuration, the tip portions defines an increasing tapered surface having a larger diameter at a distal end of the tip portion; advancing a prosthetic valve through the distal end of the sheath member, to the ring portion; advancing the prosthetic valve through the ring portion to the tip portion; advancing the prosthetic valve through the tip portion such that the prosthetic valve at least partially expands within the tip portion and the tip portion moves from the folded to the unfolded configuration in response to the outward directed radial force of the prosthetic heart valve passing through the tip portion; advancing the prosthetic valve beyond a distal end of the delivery sheath to a treatment site.

The method according to any example herein, wherein the tip portion is biased towards a folded configuration such that the tip portion returns toward the folded configuration after the prosthetic heart valve has fully passed through the tip portion.

The method according to any example herein, wherein the folding region is defined by a first (outer) circumferential portion, a first and second longitudinal edges, and a second (intermediate) circumferential portion extending between the first and second longitudinal edges, such that the first folding region is configured to crease at the first and second longitudinal edges into the folded configuration such that the first and second circumferential portions at least partially overlap, and the second circumferential portion is radially inward of the first circumferential portion, wherein advancing the prosthetic valve through the tip portion causes the first and second circumferential portions to move to a less overlapping position than when in the folded configuration, wherein advancing the prosthetic valve through the tip portion causes the first and second circumferential portions to circumferentially align when the tip portion is a fully unfolded configuration.

The method according to any example herein, further comprising withdrawing the prosthetic valve from the treatment site by moving the prosthetic valve in a direction towards the sheath member such that the prosthetic valve is withdrawn (e.g., fully or partially) into the tip portion, wherein the prosthetic valve is disposed in an at least a partially expanded configuration when outside of the delivery sheath, and wherein a tapered inner surface of the tip portion facilitates the compression (e.g., folding and/or crimping) of the prosthetic heart valve as it is withdrawn into the tip portion and towards the sheath member.

The method according to any example herein, wherein withdrawing the prosthetic valve from the treatment site further comprises: retaining the prosthetic valve in the sheath member and/or the ring portion, removing the delivery sheath from the blood vessel, and removing the delivery sheath from the introducer sheath.

The method according to any example herein, wherein the prosthetic valve is a self-expanding heart valve.

A method of deploying a prosthetic valve comprising: inserting an introducer sheath into a blood vessel; inserting a delivery sheath into a central lumen of the introducer sheath, with a prosthetic valve disposed therein, the delivery sheath comprising: a sheath member defining a tubular structure extending between a proximal end and a distal end of the sheath member; a tip portion provided at the distal end of the sheath member, the tip portion having a central lumen extending therethrough, where the tip portion is discontinuous having two flaps extending circumferentially around the tip portion, the tip portion is movable between an expanded and an unexpanded configuration, in the unexpanded configuration the tip portion defines a constant diameter along its length, in the expanded configuration, the tip portion flares open increasing a diameter of the distal end of the tip portion and increasing the spacing between the two flaps; advancing a prosthetic valve through the distal end of the sheath member, to the tip portion; advancing the prosthetic valve through the tip portion to a treatment site such that the prosthetic valve at least partially expands within the tip portion and the tip portion moved from the unexpanded to the expanded configuration in response to the outward directed radial force of the prosthetic heart valve passing through the tip portion; advancing the prosthetic valve beyond a distal end of the delivery sheath to a treatment site.

The method according to any example herein, wherein the tip portion is biased towards an unexpanded configuration such that the tip portion returns toward the unexpanded configuration after the prosthetic heart valve has fully passed through the tip portion.

The method according to any example herein, wherein, in the unexpanded configuration, the first and second flaps are formed around the tip portion with longitudinally extending gaps provided between the longitudinal sides of each of the first and second flap, wherein advancing the prosthetic valve through the tip portion causes the gaps between the longitudinal sides of each of the first and second flap to increase.

The method according to any example herein, wherein, in the unexpanded configuration, the first and second flaps are coupled to each other along weakened side edges, wherein advancing the prosthetic valve through the tip portion causes the first and second flaps to separate along the weakened side edges to increase the spacing between adjacent flaps.

Claim 1:
A delivery sheath system for percutaneous delivery and implantation of a self-expanding prosthetic heart valve (<NUM>), the delivery sheath system comprising:
a sheath member (<NUM>) defining a tubular structure extending between a proximal end and a distal end of the sheath member (<NUM>);
a tip portion (<NUM>) provided at the distal end of the sheath member (<NUM>), the tip portion (<NUM>) having a central lumen extending therethrough,
wherein at least one cross-sectional segment of an inner surface (<NUM>) of the tip portion (<NUM>) includes alternating portions of concave and convex curvature (<NUM>);
wherein the portions of concave and convex curvature (<NUM>, <NUM>) extend longitudinally along the tip portion (<NUM>);
wherein a diameter of the inner surface (<NUM>) of the tip portion (<NUM>) at a distal end of the tip portion (<NUM>) is greater than a diameter of the inner surface (<NUM>) at a proximal end of the tip portion (<NUM>) creating a decreasing tapered surface extending between the distal end and the proximal end of the tip portion (<NUM>),
wherein the tapered inner surface (<NUM>) of the tip portion (<NUM>) including the portions of concave and convex curvature (<NUM>, <NUM>) is configured to fold or crimp the heart valve (<NUM>) during withdrawal into the sheath member (<NUM>) and to counteract an outward radial force of the self-expanding heart valve (<NUM>).