Cross-Reference to Related Applications

This application claims the benefit of U.S. Provisional Application No.

62/204,038, filed August 12, 2015 and U.S. Utility Application No. 15/219,869, filed July 26, 2016.

Technical Field

The present disclosure pertains to medical devices, and methods for manufacturing and/or using medical devices. More particularly, the present disclosure pertains to locking mechanisms for a medical device and/or a replacement heart valve.

Background

A wide variety of intracorporeal medical devices have been developed for medical use, for example, intravascular use. Some of these devices include guidewires, catheters, medical device delivery systems (e.g., for stents, grafts, replacement valves, etc.), and the like. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods. Of the known medical devices and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing and using medical devices.

Summary

In a first aspect, a locking mechanism for a medical implant may comprise a buckle member fixedly attached to a tubular anchor member, the tubular anchor member defining a central longitudinal axis, a post member axially translatable relative to the buckle member generally parallel to the central longitudinal axis when the post member is at least partially disposed within the buckle member, wherein the post member includes a first proximal portion and a second proximal portion disposed parallel to a longitudinal axis of the post member, the first proximal portion being disposed adjacent to the tubular anchor member and the second proximal portion being disposed radially inward of the first proximal portion, and an actuator element including a lateral protrusion proximate a distal end thereof, the actuator element being releasably coupled to the post member. The post member may include an engagement portion configured to engage the buckle member such that movement of the post member distally relative to the buckle member is prevented. The second proximal portion may be configured to deflect away from the first proximal portion to release the actuator element.

In addition or alternatively, and in a second aspect, at least a portion of the actuator element extends between the first proximal portion and the second proximal portion.

In addition or alternatively, and in a third aspect, the lateral protrusion is configured to engage with an aperture disposed within the second proximal portion.

In addition or alternatively, and in a fourth aspect, the aperture extends through the second proximal portion.

In addition or alternatively, and in a fifth aspect, the first proximal portion and the second proximal portion are configured to splay apart as the post member is translated proximally.

In addition or alternatively, and in a sixth aspect, the second proximal portion is self-biased toward the first proximal portion.

In addition or alternatively, and in a seventh aspect, the post member is coupled to a distal end of the tubular anchor member.

In addition or alternatively, and in an eighth aspect, the actuator element includes a longitudinally-oriented rib extending distally from the lateral protrusion.

In addition or alternatively, and in a ninth aspect, the buckle member includes a deflectable flap portion configured to engage the engagement portion of the post member, the longitudinally-oriented rib being configured to prevent the flap portion of the buckle member from engaging the engagement portion prior to decoupling the actuator element from the post member.

In addition or alternatively, and in a tenth aspect, a medical implant may comprise a tubular anchor member actuatable between an elongated delivery configuration and an expanded deployed configuration, the tubular anchor member defining a central longitudinal axis, a buckle member fixedly attached to the tubular anchor member, a post member axially translatable relative to the buckle member, the post member including an engagement portion configured to engage the buckle member when the anchor member is in the deployed configuration, a first proximal portion, and a second proximal portion disposed closer to the central longitudinal axis than the first proximal portion, an actuator element including a lateral protrusion proximate a distal end thereof, the actuator element being releasably connected to the post member, and a valve leaflet attached to the post member. The post member may be disposed distal of the anchor member when the anchor member is in the elongated delivery configuration. The second proximal portion may be configured to deflect away from the first proximal portion to release the actuator element.

In addition or alternatively, and in an eleventh aspect, the second proximal portion includes a ramp facing towards the first proximal portion, the ramp being angled away from the first proximal portion in a proximal direction.

In addition or alternatively, and in a twelfth aspect, at least a portion of the actuator element extends between the first proximal portion and the second proximal portion.

In addition or alternatively, and in a thirteenth aspect, the second proximal portion includes an aperture extending therethrough, the aperture being configured to engage with the lateral protrusion.

In addition or alternatively, and in a fourteenth aspect, the second proximal portion extends alongside and is offset radially inward from the first proximal portion.

In addition or alternatively, and in a fifteenth aspect, a medical implant system may comprise a medical implant of the tenth aspect, a delivery system having a handle attached at a proximal end thereof, and a deployment member extending from the delivery system to the medical implant, the deployment member being releasably coupled to the buckle member. Proximal retraction of the post member through the buckle member may engage the post member with the deployment member.

In addition or alternatively, and in a sixteenth aspect, proximal retraction of the post member through the buckle member disposes the deployment member between the first proximal portion and the second proximal portion.

In addition or alternatively, and in a seventeenth aspect, the deployment member urges the second proximal portion away from the first proximal portion.

In addition or alternatively, and in an eighteenth aspect, proximal retraction of the post member through the buckle member deflects the second proximal portion toward the central longitudinal axis.

In addition or alternatively, and in a nineteenth aspect, the actuator element includes a second lateral protrusion extending opposite the lateral protrusion.

In addition or alternatively, and in a twentieth aspect, the first proximal portion includes an aperture extending therethrough, the aperture of the first proximal portion being configured to receive the second lateral protrusion therein when the actuator element is releasably coupled to the post member.

The above summary of some embodiments, aspects, and/or examples is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The Figures, and Detailed Description, which follow, more particularly exemplify these embodiments.

Brief Description of the Drawings

The disclosure may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which:

FIG. 1 illustrates an example medical device system;

FIG. 2 is a perspective view of an example medical implant;

FIG. 3 illustrates an example actuator element;

FIG. 4 illustrates an example post member;

FIG. 5 illustrates selected components of an example medical implant associated with an example medical device system in a delivery configuration;

FIG. 6 illustrates selected components of an example medical implant associated with an example medical device system;

FIG. 7 illustrates selected components of an example medical implant associated with an example medical device system in a deployed configuration;

FIG. 8 illustrates selected components of an example medical implant associated with an example medical device system in a released configuration;

FIG. 9 is a side view of selected components of an example medical implant associated with an example medical device system in a delivery configuration;

FIG. 10 is a partial cross-sectional view of selected components of an example medical implant associated with an example medical device system;

FIG. 11 is a partial cross-sectional view of selected components of an example medical implant associated with an example medical device system in a deployed configuration; and

FIG. 12 is a partial cross-sectional view of selected components of an example medical implant associated with an example medical device system in a released configuration. While aspects of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

Detailed Description

The following description should be read with reference to the drawings, which are not necessarily to scale, wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings are intended to illustrate but not limit the claimed invention. Those skilled in the art will recognize that the various elements described and/or shown may be arranged in various combinations and configurations without departing from the scope of the disclosure. The detailed description and drawings illustrate example embodiments of the claimed invention.

Generally speaking, in terms of the orientation of the structural elements relative to each other and the operation of the disclosed device(s), a proximal end may be considered closest to the user (or external to a patient) and a distal end farthest from the user (or internal to a patient). However, the skilled artisan will appreciate that the orientations and/or directions may be reversed as necessary or appropriate.

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

All numeric values are herein assumed to be modified by the term "about," whether or not explicitly indicated. The term "about", in the context of numeric values, generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term "about" may include numbers that are rounded to the nearest significant figure. Other uses of the term "about" (i.e., in a context other than numeric values) may be assumed to have their ordinary and customary definition(s), as understood from and consistent with the context of the specification, unless otherwise specified.

The recitation of numerical ranges by endpoints includes all numbers within that range, including the endpoints (e.g. 1 to 5 includes 1 , 1.5, 2, 2.75, 3, 3.80, 4, and 5). Although some suitable dimensions, ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

Relative terms such as "proximal", "distal", "advance", "retract", variants thereof, and the like, may be generally be considered with respect to the positioning, direction, and/or operation of various elements relative to a user/operator/manipulator of the device, wherein "proximal" and "retract" indicate or refer to closer to or toward the user and "distal" and "advance" indicate or refer to farther from or away from the user.

It is noted that references in the specification to "an embodiment", "some embodiments", "other embodiments", etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described, unless clearly stated to the contrary. That is, the various individual elements described below, even if not explicitly shown in a particular combination, are nevertheless contemplated as being combinable or arrangable with each other to form other additional embodiments or to complement and/or enrich the described embodiment(s), as would be understood by one of ordinary skill in the art.

For the purpose of clarity, certain identifying numerical nomenclature (e.g., first, second, third, fourth, etc.) may be used throughout the description and/or claims to name and/or differentiate between various described and/or claimed features. It is to be understood that the numerical nomenclature is not intended to be limiting and is exemplary only. In some embodiments, alterations of and deviations from previously- used numerical nomenclature may be made in the interest of brevity and clarity. That is, a feature identified as a "first" element may later be referred to as a "second" element, a "third" element, etc. or may be omitted entirely, and/or a different feature may be referred to as the "first" element. The meaning and/or designation in each instance will be apparent to the skilled practitioner.

Diseases and/or medical conditions that impact the cardiovascular system are prevalent in the United States and throughout the world. Traditionally, treatment of the cardiovascular system was often conducted by directly accessing the impacted part of the system. For example, treatment of a blockage in one or more of the coronary arteries was traditionally treated using coronary artery bypass surgery. As can be readily appreciated, such therapies are rather invasive to the patient and require significant recovery times and/or treatments. More recently, less invasive therapies have been developed, for example, where a blocked coronary artery could be accessed and treated via a percutaneous catheter (e.g., angioplasty). Such therapies have gained wide acceptance among patients and clinicians.

Some relatively common medical conditions may include or be the result of inefficiency, ineffectiveness, or complete failure of one or more of the valves within the heart. For example, failure of the aortic valve can have a serious effect on a human and could lead to serious health condition and/or death if not dealt with. Treatment of defective heart valves poses other challenges in that the treatment often requires the repair or outright replacement of the defective valve. Such therapies may be highly invasive to the patient. Disclosed herein are medical devices that may be used for delivering a medical device to a portion of the cardiovascular system in order to diagnose, treat, and/or repair the system. At least some of the medical devices disclosed herein may be used to deliver and implant a replacement heart valve (e.g., a replacement aortic valve). In addition, the devices disclosed herein may deliver the replacement heart valve percutaneously and, thus, may be much less invasive to the patient. The devices disclosed herein may also provide a number of additional desirable features and benefits as described in more detail below.

The figures illustrate selected components and/or arrangements of a medical device system 10. It should be noted that in any given figure, some features of the medical device system 10 may not be shown, or may be shown schematically, for simplicity. Additional details regarding some of the components of the medical device system 10 may be illustrated in other figures in greater detail. A medical device system 10 may be used to deliver and/or deploy a variety of medical devices to a number of locations within the anatomy. In at least some embodiments, the medical device system 10 may include a replacement heart valve delivery system (e.g., a replacement aortic valve delivery system) that can be used for percutaneous delivery of a replacement heart valve. This, however, is not intended to be limiting as the medical device system 10 may also be used for other interventions including mitral valve replacement, valve repair, valvuloplasty, and the like, or other similar interventions.

The medical device system 10, as seen in FIG. 1 for example, may generally be described as a catheter system that includes a delivery system 12 and a medical implant 16 (i.e., a replacement heart valve, for example, which term may be used interchangeably with the term "medical implant" herein) which may be coupled to the delivery system 12 and disposed within a lumen of the delivery system 12 during delivery of the medical implant 16. In some embodiments, a handle 18 may be disposed and/or attached at a proximal end of the delivery system 12, and may include one or more actuation means associated therewith. In general, the handle 18 may be configured to manipulate the position of the delivery system 12 and/or aid in the deployment of the medical implant 16.

In use, the medical device system 10 may be advanced percutaneously through the vasculature to a position adjacent to an area of interest or a target location. For example, the medical device system 10 may be advanced through the vasculature and across the aortic arch to a position adjacent to a defective aortic valve. Alternative approaches to treat a defective aortic valve or other heart valve(s) are also contemplated with the medical device system 10. During delivery, the medical implant 16 may be generally disposed in an elongated and low profile "delivery" configuration within the delivery system 12. Once positioned, the delivery system 12 may be retracted relative to the medical implant 16 to expose the medical implant 16. In at least some embodiments, the medical implant 16 may be disposed in an "everted" configuration or a partially-everted configuration while disposed within the delivery system 12 and/or immediately upon exposure after retracting the delivery system 12. In some embodiments, the medical implant 16 may be everted in the "delivery" configuration. In some embodiments, the "delivery" configuration and the "everted" configuration may be substantially similar and/or may be used interchangeably herein. The medical implant 16 may be actuated using the handle 18 in order to translate the medical implant 16 into a generally expanded and larger profile "deployed" configuration suitable for implantation within the anatomy (as shown in FIG. 2, for example). When the medical implant 16 is suitably deployed within the anatomy, the delivery system 12 can be removed from the vasculature, leaving the medical implant 16 in place in a "released" configuration to function as, for example, a suitable replacement for the native aortic valve. In at least some interventions, the medical implant 16 may be deployed within the native valve (e.g., the native valve is left in place and not excised). Alternatively, the native valve may be removed and the medical implant 16 may be deployed in its place as a replacement.

In some embodiments, the delivery system 12 may include one or more lumens extending therethrough. For example, in some embodiments, the delivery system 12 may include a first lumen, a second lumen, a third lumen, and a fourth lumen. Other configurations are also contemplated. In general, the one or more lumens extend along an entire length of the delivery system 12. Other embodiments are contemplated, however, where one or more of the one or more lumens extend along only a portion of the length of the delivery system 12. For example, in some embodiments, the fourth lumen may stop just short of a distal end of the delivery system 12 and/or be filled in at its distal end to effectively end the fourth lumen proximal of the distal end of the delivery system 12.

Disposed within a first lumen of the delivery system 12 may be at least one actuator element, such as an actuator element 84 for example, which may be used to actuate (i.e., expand and/or elongate) the medical implant 16 between a delivery configuration and a deployed configuration. In some cases, the actuator element(s) 84 may herein be referred to, or used interchangeably with, the term "actuator element". In some embodiments, the medical device system 10 may include at least one actuator element 84. In some embodiments, the at least one actuator element 84 may include a plurality of actuator elements 84, two actuator elements 84, three actuator elements 84, four actuator elements 84, or another suitable or desired number of actuator elements 84. For the purpose of illustration only, the medical device system 10 and/or the medical implant 16 is shown with three actuator elements 84.

In at least some embodiments, the first lumen may be lined with a low friction liner (e.g., a FEP liner). In some embodiments, disposed within a second lumen may be at least one release pin, although dedicated release pins are not strictly necessary in every embodiment. In at least some embodiments, the second lumen may be lined with a hypotube liner. A third lumen may be a guidewire lumen and in some embodiments, the third lumen may also be lined with a hypotube liner. In some embodiments, a fourth lumen may be used to house a non-stretch wire or other reinforcing member. The form of the non-stretch wire or other reinforcing member may vary. In some embodiments, the non-stretch wire may take the form of a stainless steel braid. The non-stretch wire may optionally include a pair of longitudinally-extending aramid and/or para aramid strands (for example, KEVLAR®) disposed on opposite sides of the braid. In general, rather than being "disposed within" the fourth lumen, the non-stretch wire may be embedded within the fourth lumen. In addition, the non-stretch wire may extend to a position adjacent to a distal end region but not fully to the distal end of the delivery system 12. For example, a short distal segment of the fourth lumen may be filled in with polymer material adjacent to the distal end of the delivery system 12.

The delivery system 12 may also include a guidewire tube extension that extends distally from the distal end region. In some embodiments, a nose cone may be attached to the guidewire tube extension. In some embodiments, the nose cone generally is designed to have an atraumatic shape. In some embodiments, the nose cone may also include a ridge or ledge that is configured to abut the distal tip of the delivery system 12 during delivery of the medical implant 16.

It is to be noted that in order to facilitate understanding, certain features of the disclosure may be described in the singular, even though those features may be plural or recurring within the disclosed embodiment(s). Each instance of the features may include and/or be encompassed by the singular disclosure(s), unless expressly stated to the contrary. For example, a reference to "the actuator element" may be equally referred to all instances and quantities beyond one of "the at least one actuator element".

FIG. 2 illustrates some selected components of the medical device system 10 and/or the medical implant 16. For example, here it can be seen that the medical implant 16 may include a plurality of valve leaflets 68 (e.g., bovine pericardial) which may be secured to a tubular anchor member or braid 70 that is reversibly actuatable between an elongated "delivery" configuration, and an expanded "deployed" configuration. In some embodiments, the anchor member or braid 70 may define a central longitudinal axis. In some embodiments, the medical implant 16 may include at least one locking mechanism 58 configured to lock the anchor member or braid 70 in the "deployed" configuration. In some embodiments, at least one actuator element 84 may be configured to engage the at least one locking mechanism 58 and actuate the anchor member or braid 70 and/or the medical implant 16 between the "delivery" configuration and the "deployed" configuration and/or the "released" configuration. In some embodiments, one actuator element 84 may correspond to, engage with, and/or actuate one locking mechanism 58. In some embodiments, one actuator element 84 may correspond to, engage with, and/or actuate more than one locking mechanism 58. Other configurations are also contemplated.

FIG. 3 illustrates an example actuator element 84. In some embodiments, an example actuator element 84 may include a proximal end and a distal end. In use, the proximal end may be connected to a handle 18, and/or manipulated or otherwise actuated by a user using the handle 18, to shift the medical implant 16 from a "delivery" configuration to a "deployed" configuration, and later to a "released" configuration. In some embodiments, the actuator element 84 may be axially translatable relative to a buckle member 76 of the medical implant 16. In some embodiments, the actuator element 84 may be axially translatable within and/or through a longitudinal channel of the buckle member 76, as seen in FIGS. 5-12 for example.

In some embodiments, the actuator element 84 may include an elongated rod and a distal end portion. In some embodiments, the actuator element 84 and/or the distal end portion may be releasably connected and/or coupled to a proximal end of the post member 96. In some embodiments, the distal end portion may be integrally formed with or as a part of the elongated rod as a single monolithic structure. In some embodiments, the actuator element 84 may be prevented from rotating (i.e., is non- rotatable) relative to the buckle member 76 when the actuator element 84 is engaged with the buckle member 76. In some embodiments, the actuator element 84 may be prevented from rotating (i.e., is non-rotatable) relative to the post member 96 when the actuator element 84 is engaged with the post member 96.

In some embodiments, the distal end portion may include a lateral protrusion 86 extending transversely to a longitudinal axis of the elongated rod, the lateral protrusion 86 being fixedly attached and/or secured thereto. In some embodiments, the distal end portion may include more than one lateral protrusion 86 fixedly attached and/or secured thereto. In some embodiments, the actuator element 84 may include a second lateral protrusion extending opposite the lateral protrusion 86. In some embodiments, the lateral protrusion 86 may be integrally formed with or as a part of the distal end portion and/or the actuator element 84 as a single monolithic structure. In some embodiments, the at least one actuator element 84 may include a longitudinally-oriented rib 102 extending distally from the lateral protrusion 86. In some embodiments, the longitudinally-oriented rib 102 may be integrally formed with or as a part of the distal end portion, the lateral protrusion 86, and/or the actuator element 84 as a single monolithic structure.

In some embodiments, the actuator element 84 may be aligned with and/or releasably coupled to the proximal end of the post member 96. In some embodiments, the distal end portion may be slidingly received between a first proximal portion 90 and a second proximal portion 92 of the post member 96. In some embodiments, the lateral protrusion 86 may be configured to engage with, be received by, and/or extend into an aperture 98 formed within the second proximal portion 92 of the post member 96. In some embodiments, the first proximal portion 90 may include an aperture extending therethrough, the aperture of the first proximal portion 90 being configured to receive and/or engage with the second lateral protrusion therein when the actuator element 84 is releasably coupled to the post member 96.

In some embodiments, the actuator element 84 and/or the elongated rod may be generally round, oblong, ovoid, rectangular, polygonal (i.e., two-sided, three-sided, four-sided, five-sided, six-sided, etc.) and/or combinations thereof in shape. Other shapes, both regular and irregular, are also contemplated. In some embodiments, the actuator element 84 may be formed from a single piece of wire, round stock, or other suitable material, as discussed herein. In some embodiments, the actuator element 84 may be formed by further processing the single piece of wire, round stock, or other suitable material, such as by machining, stamping, laser cutting, etc. Some suitable but non-limiting materials for the actuator element 84, the elongated rod, the distal end portion, and/or the lateral protrusion 86, for example metallic materials or polymeric materials, may be described below.

FIG. 4 illustrates an example post member 96. In some embodiments, the post member 96 may include an elongated member configured to engage with and/or releasably coupled to the actuator element 84. In some embodiments, the post member 96 may include a longitudinally-extending passageway extending therethrough. In some embodiments, the post member 96 may be substantially solid. In some embodiments, the post member 96 may include one or more laterally-extending bars 97 at a distal end thereof, the one or more laterally-extending bars 97 configured to engage with a proximal end of the commissure post(s) 72, thereby preventing relative movement therebetween. In some embodiments, the actuator element 84 may be slidably disposed within the passageway and/or may be releasably coupled to the post member 96 by a lateral protrusion 86 at, proximate, and/or adjacent a distal end of the actuator element 84, as seen in FIGS. 5-12, for example. In some embodiments, at least a portion of the at least one actuator element 84 may extend between the first proximal portion 90 and the second proximal portion 92, as seen in FIGS. 5 and 9 for example, when the lateral protrusion 86 and/or the at least one actuator element 84 is engaged with the post member 96. In some embodiments, the post member 96 may be disposed distal of the anchor member or braid 70 when the anchor member or braid 70 is in the elongated "delivery" configuration and/or the "everted" configuration.

In some embodiments, the post member 96 may include a first proximal portion 90 and a second proximal portion 92 disposed generally parallel to a longitudinal axis of the post member 96. In some embodiments, the first proximal portion 90 may be disposed adjacent to the anchor member or braid 70 when the post member 96 is engaged with the buckle member 76. In some embodiments, the longitudinal axis of the post member 96 may be arranged generally parallel to the central longitudinal axis of the anchor member or braid 70. In some embodiments, the second proximal portion 92 may be disposed closer to the central longitudinal axis of the anchor member or braid 70 than the first proximal portion 90 when the post member 96 is engaged with the buckle member 76. In some embodiments, the second proximal portion 92 may be disposed radially inward of the first proximal portion 90 with respect to the central longitudinal axis of the anchor member or braid 70 when the post member 96 is engaged with the buckle member 76. In some embodiments, the second proximal portion 92 may extend alongside and may be offset radially inward from the first proximal portion 90 when the post member 96 is engaged with the buckle member 76.

In some embodiments, the second proximal portion 92 may include a ramp 91 facing toward the first proximal portion 90, the ramp 91 being angled away from the first proximal portion 90 in a proximal direction when the post member is engaged with the buckle member 76. In some embodiments, the first proximal portion 90 may include an aperture disposed within and/or extending through the first proximal portion 90. In some embodiments, the second proximal portion 92 may include an aperture 98 disposed within the second proximal portion 92. In some embodiments, the aperture 98 may extend through the second proximal portion 92.

In some embodiments, the lateral protrusion 86 and/or the at least one actuator element 84 may engage the post member(s) 96 of the at least one locking mechanism 58. In some embodiments, the aperture 98 of the second proximal portion 92 may be configured to receive the lateral protrusion 86 therein such that the lateral protrusion 86 extends into and/or engages with the aperture 98 of the second proximal portion 92. In some embodiments, a second lateral protrusion may extend into and/or engage with (also or alternatively) the aperture of the first proximal portion 90.

In some embodiments, engagement of the lateral protrusion 86 with the aperture 98 may permit the at least one actuator element 84 to axially translate the post member 96 relative to the buckle member 76. In some embodiments, the second proximal portion 92 may be self-biased toward the first proximal portion 90 to retain the lateral protrusion 86 within the aperture 98. In some embodiments, the second proximal portion 92 may be configured to deflect away from the first proximal portion 90 to release the at least one actuator element 84. In some embodiments, the first proximal portion 90 and the second proximal portion 92 may be configured to splay apart as the post member 96 is translated proximally. Some suitable but non-limiting materials for the post member 96, for example metallic materials or polymeric materials, may be described below.

In some embodiments, the post member 96 may include an engagement portion 94 having a first transversely-oriented ridge 100, the first transversely-oriented ridge 100 being configured to engage with a second transversely-oriented ridge of a deflectable flap portion 30 of a buckle member 76 to axially "lock" the medical implant 16 into the "deployed" configuration such that movement of the post member 96 distally relative to the buckle member 76 is prevented after the at least one actuator element 84 and/or the lateral protrusion 86 has been disengaged from the post member 96.

In some embodiments, the at least one locking mechanism 58 may each comprise a post member 96, for example at the commissure portions of the valve leaflets 68 (the post member 96 may sometimes be referred to as a portion of a commissure post 72, which may serve to secure the valve leaflets 68, or the post member 96 may be connected and/or attached to a commissure post 72), and a buckle member 76 or other receiving element configured to slidably receive the post member 96 therein, as seen in FIGS. 5-12 for example. In other words, in at least some embodiments, a medical implant 16 may include at least one or a plurality of post members 96 and a corresponding at least one or a plurality of buckle members 76, as seen in FIG. 2 for example. Other configurations and correspondences are also contemplated. In some embodiments, the valve leaflets 68 may also be secured to a base or distal end of the anchor member or braid 70. The post members 96 and/or the commissure posts 72, in turn, may be secured and/or attached to the anchor member or braid 70 (e.g., along the interior of the anchor member or braid 70) with sutures, adhesives, or other suitable mechanisms. In some embodiments, the commissure post 72 and/or the post member 96 may include one or more holes or other features provided to aid in securing and/or attaching the commissure post 72 and/or the post member 96 to the anchor member or braid 70. Positioned adjacent to (e.g., aligned with) the plurality of post members 96 are a corresponding plurality of buckle members 76, which may be secured and/or fixedly attached to the anchor member or braid 70 (e.g., along the interior of the anchor member or braid 70) with sutures, adhesives, or other suitable mechanisms. In some embodiments, the post member 96 may be axially translatable relative to the buckle member 76 generally parallel to the central longitudinal axis of the anchor member or braid 70 when the post member 96 is at least partially disposed within and/or engaged with the buckle member 76.

In some embodiments, one buckle member 76 may be fixedly attached to the anchor member or braid 70 adjacent to each of the three post members 96. Accordingly, in some embodiments, the anchor member or braid 70 may have a total of three buckle members 76 and three post members 96 attached thereto. Similarly, one actuator element 84 may be associated with each post member 96 and buckle member 76, for a total of three actuator elements 84 in the illustrated example(s). Other embodiments are contemplated where fewer or more buckle members 76, post members 96, and/or actuator elements 84 may be utilized. In some embodiments, a seal 20 (shown in partial cross-section in FIG. 2) may be disposed on and/or about the anchor member or braid 70 and may help to seal the medical implant 16 within a target site or area of interest upon deployment.

In some embodiments, the buckle member 76 may include a base portion 32 having a longitudinal axis extending between a proximal end and a distal end thereof. In some embodiments, the buckle member 76 may include a rail 108 disposed at the proximal end of the buckle member 76 and/or extending proximally from the base portion 32 of the buckle member 76, as seen in FIGS. 7-8 and 11 -12 for example. In some embodiments, the buckle member 76 may include a body portion 34 defining a longitudinal channel extending therethrough. In at least some embodiments, the longitudinal channel may be oriented substantially parallel to the longitudinal axis of the base portion 32. In some embodiments, at least a part of the body portion 34 may extend upwardly from a distal portion of the base portion 32, as seen in FIGS. 5-12 for example.

In some embodiments, the buckle member 76 may include a flap portion 30 extending proximally and/or toward the proximal end of the base portion 32 from the body portion 34. In some embodiments, the flap portion 30 may include a second transversely-oriented ridge extending downwardly toward the base portion and laterally across the base portion 32, such that when the buckle member 76 is viewed along the longitudinal axis of the base portion 32, the second transversely-oriented ridge obstructs at least a portion of the longitudinal channel.

In at least some embodiments, the buckle member 76 may be configured to slidably receive at least a portion of the post member 96 within the longitudinal channel. In some embodiments, the buckle member 76 may include one or more holes or other features provided to aid in attaching the buckle member 76 to the anchor member or braid 70. Some suitable but non-limiting materials for the buckle member 76, for example metallic materials or polymeric materials, may be described below.

In some embodiments, attachment between the medical implant 16 and the delivery system 12 may be effected through the use of a coupler 78, as seen in FIG. 2 for example. The coupler 78 may generally include a base (not shown) that may be attached to a portion of the delivery system 12. Projecting distally from the base is a plurality of deployment members 79 (e.g., two, three, four, etc.) that are each configured to engage with the medical implant 16 at one of the buckle members 76. In some embodiments, each of the plurality of deployment members 79 may extend from the delivery system 12 to the medical implant 16. In some embodiments, each deployment member 79 may include two elongated tines 104 (as described further below and seen in FIGS. 7 and 8) held in engagement with one buckle member 76 by a collar 80 slidably disposed about the respective deployment member 79 and the respective buckle member 76. A guide 82 may be disposed over each of the deployment members 79 proximal of the collar 80 and may serve to keep the deployment members 79 of the coupler 78 associated with the actuator elements 84 extending adjacent to (and axially slidable relative to) the deployment members 79 of the coupler 78. In at least some embodiments, the at least one actuator element 84 may extend between the two elongated tines 104 of the deployment member(s) 79.

During delivery, the medical implant 16 may be secured at the distal end of the delivery system 12 by virtue of the two elongated tines 104 of the deployment members 79 of the coupler 78 being matingly coupled with a corresponding rail 108, disposed at a proximal end of the buckle member 76, by the collar 80 as seen in FIGS. 6 and 7, and by virtue of the at least one actuator element 84 being coupled to the corresponding post member 96. When the medical implant 16 is advanced within the anatomy to the desired location, at least part of the delivery system 12 may be translated and/or actuated proximally to expose the medical implant 16. Then, the at least one actuator element 84 can be actuated (e.g., proximally retracted) to axially shorten and/or radially expand the medical implant 16 and/or the anchor member or braid 70 from the "delivery" configuration toward an expanded or "deployed" configuration by proximally retracting the at least one actuator element 84 to pull the post members 96 into engagement with the buckle members 76, using the handle 18 for example. After verifying satisfactory placement of the medical implant 16, such as by an appropriate imaging technique, the at least one actuator element 84 may be decoupled from the post members 96, which allows the at least one actuator element 84 to be pulled proximally out of the buckle members 76, where the longitudinally-oriented rib 102 engages the collar 80 and thereby retracts the collar 80 from the two elongated tines 104. Once the collar 80 has been retracted, the two elongated tines 104 decouple from the rail 108, and the deployment members 79 of the coupler 78 may be withdrawn from the medical implant 16 thereby leaving the medical implant 16 (and/or the anchor member or braid 70) in the anatomy in a "released" configuration.

FIGS. 5-12 illustrate selected components of an example locking mechanism 58 configured to reversibly lock the medical implant 16 (and/or the anchor member or braid 70) in the "deployed" configuration and/or the "released" configuration, and the general operation of those components. For simplicity and clarity purposes, only one of the deployment members 79, only one of the at least one actuator element 84, only one of the post members 96, and only one of the buckle members 76 are shown and discussed (the whole medical implant 16 and/or the anchor member or braid 70 is not shown to facilitate understanding of the locking mechanism(s) 58). However, it will be understood that the following discussion may apply equally to any and/or all of the components for which there are more than one within the medical implant 16 (i.e., the at least one actuator element 84, the buckle members 76, the post members 96, etc.) and/or the medical device system 10, unless explicitly stated to the contrary.

As seen in FIGS. 5-12, each of the at least one actuator element 84 extends through a guide 82 adjacent to and encompassing the deployment member 79 of the coupler 78, through the collar 80, through a buckle member 76, and into engagement with a post member 96. The at least one actuator element 84 may be axially translatable through the guide 82, the collar 80, and/or the buckle member 76. The at least one actuator element 84 may be axially translatable through and/or within a portion of the post member 96 under certain conditions. In some embodiments, a distal portion of the at least one actuator element 84 may include a lateral protrusion 86 configured to engage and/or extend into an aperture 98 of the post member 96.

The lateral protrusion 86 may releasably couple the at least one actuator element 84 to the post member 96 and form a configuration of these structures that can be utilized during delivery of the medical implant 16. As can be appreciated, a proximal end of the post member 96 and a distal end of the buckle member 76 may be longitudinally separated (as seen in FIGS. 5 and 9, for example) and, accordingly, the medical implant 16 and/or the anchor member or braid 70 may be in an elongated and generally low-profile "delivery" configuration suitable for percutaneous translation through a patient's anatomy to an area of interest and/or target site. In at least some embodiments, the post member 96 and the buckle member 76 may be longitudinally moveable and/or translatable relative to each other in the "delivery" configuration.

When the medical implant 16 reaches the intended target site within the anatomy, a clinician can actuate (e.g., proximally retract) the at least one actuator element 84, thereby moving and/or translating the proximal end of the post member 96 toward the distal end of the buckle member 76 in order to axially shorten and/or radially expand the anchor member or braid 70 and/or the medical implant 16 towards the "deployed" configuration. Ultimately, the at least one actuator element 84 can be retracted sufficiently far enough to position the first transversely-oriented ridge 100 of the post member 96 adjacent to a flap portion 30 of the buckle member 76 wherein the medical implant 16 and/or the anchor member or braid 70 is at an axial position (along and/or relative to the central longitudinal axis of the anchor member or braid 70) corresponding to the "deployed" configuration (as seen in FIGS. 6 and 10, for example), suitable for implantation within the anatomy. In other words, in some embodiments, axial translation of the at least one actuator element 84 in a first (e.g., proximal) direction may actuate the anchor member or braid 70 from the "delivery" configuration toward the "deployed" configuration. As mentioned above, in some embodiments, the at least one actuator element 84 may include a longitudinally-oriented rib 102 extending distally from the lateral protrusion 86. In some embodiments, the longitudinally- oriented rib 102 of the at least one actuator element 84 may be configured to prevent the flap portion 30 of the buckle member 76 from engaging the engagement portion 94 prior to decoupling the at least one actuator element 84 from the post member 96, as seen in FIGS. 6 and 10 for example. At this point in the deployment process, proper positioning of the medical implant 16 within the target site may be verified.

In some embodiments and/or some procedures, it may be desirable to remove and/or reposition the medical implant 16 and/or anchor member or braid 70. To do so, a clinician may urge and/or translate the at least one actuator element 84 in a second (e.g., distal) direction to extend and/or elongate the anchor member or braid 70 back towards the "delivery" configuration. Axial translation of the at least one actuator element 84 in the second (e.g., distal) direction relative to the at least one locking mechanism 58 (i.e., the post member 96 and/or the buckle member 76) may slidably engage the longitudinally-oriented rib 102 with the flap portion 30 of the buckle member 76, thereby translating the flap portion 30 of the buckle member 76 away from a longitudinal axis of the at least one actuator element 84 and/or toward the central longitudinal axis of the anchor member or braid 70, and permitting the first transversely-oriented ridge 100 of the post member 96 to pass back through the buckle member 76.

Alternatively, if a clinician is satisfied with the positioning of the medical implant 16 (e.g., after visualization of the medical implant 16 via a suitable imaging technique), the at least one actuator element 84 may be further actuated (e.g., withdrawn proximally) to decouple the lateral protrusion 86 and/or the at least one actuator element 84 from the post member 96. Once the anchor member or braid 70 has achieved the axial position corresponding to the "deployed" configuration, the proximal end of the post member 96 (and/or the first proximal portion 90 and the second proximal portion 92) engages the two elongated tines 104 of the deployment member 79. Following actuation of the anchor member or braid 70 to the axial position corresponding to the "deployed" configuration, proximal retraction of the post member 96 through the buckle member 76 may dispose the two elongated tines 104 of the deployment members 79 between the first proximal portion 90 and the second proximal portion 92. In some embodiments, further axial translation of the at least one actuator element 84 in the first (e.g., proximal) direction may deflect the first proximal portion 90 and/or the second proximal portion 92, thereby permitting the lateral protrusion 86 and/or at least one actuator element 84 to disengage from the post member 96, which thereafter permits the at least one actuator element 84 to be withdrawn from the post member 96. In some embodiments, further proximal withdrawal and/or axial translation of the at least one actuator element 84 relative to the at least one locking mechanism 58 may splay apart the first proximal portion 90 and the second proximal portion 92, thereby permitting the lateral protrusion 86 to disengage from the aperture 98 of the post member 96 and translate proximally relative to the post member 96. In some embodiments, proximal retraction of the post member 96 through the buckle member 76 may deflect the second proximal portion 92 toward the central longitudinal axis of the anchor member or braid 70. In some embodiments, the deployment members 79 may be configured to urge the second proximal portion 92 away from the first proximal portion 90.

Once the at least one actuator element 84 has been disengaged and/or detached from the post member 96, the first transversely-oriented ridge 100 of the post member 96 engages with the second transversely-oriented ridge of the flap portion 30 of the buckle member 76 and locks the medical implant 16 and/or the anchor member or braid 70 in the "deployed" configuration, as seen in FIGS. 7 and 11 for example. Further actuation and/or retraction of the at least one actuator element 84 may cause the distal portion of the at least one actuator element 84 to engage the collar 80 and pull/slide the collar 80 proximally along the deployment member 79 while withdrawing the at least one actuator element 84 from the post member 96. In doing so, the two elongated tines 104 of the deployment member 79 may be exposed, as seen in FIGS. 7 and 1 1, and decoupled from the rail 108, as seen in FIGS. 8 and 12. Withdrawal of the at least one actuator element 84 completely from the post member 96 releases the anchor member or braid 70 from the at least one actuator element 84 and leaves the medical implant 16 disposed at the target site in the "released" configuration. As seen in the transition from FIGS. 6 through 8 and FIGS. 10 through 12, after the at least one actuator element 84 is disengaged from and withdrawn from the post member 96, the collar 80 is also retracted, thus permitting the two elongated tines 104 to disengage from the rail 108 of the buckle member 76. As the two elongated tines 104 disengage and/or pull away from the rail 108, the second proximal portion 92 of the post member 96, which may be self-biased toward the first proximal portion 90, may rebound or snap back toward the first proximal portion 90 while the first transversely-oriented ridge 100 of the engagement portion 94 engages with the flap portion 30 of the buckle member 76 to lock the medical implant 16 in the "deployed" configuration. In at least some embodiments, disengagement of the at least one actuator element 84 and release of the anchor member or braid 70 and/or the medical implant 16 may be controlled by distance travelled by the at least one actuator element 84 relative to the buckle member 76. Thereafter, the delivery system 12 may be withdrawn and/or removed from the anatomy, leaving behind the expanded and deployed medical implant 16 disposed at the target site in a "released" configuration.

The materials that can be used for the various components of the medical device system 10 (and/or other systems disclosed herein) and the various elements thereof disclosed herein may include those commonly associated with medical devices. For simplicity purposes, the following discussion makes reference to the delivery system 12 and/or the medical implant 16. However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other elements, members, components, or devices disclosed herein, such as, but not limited to, the anchor member or braid 70, the actuator element 84, the post member 96, the buckle member 76, and/or elements or components thereof.

In some embodiments, the delivery system 12 and/or the medical implant 16, and/or components thereof, may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material.

Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene- )-isobutylene- )- styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments the sheath can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about 6 percent LCP.

Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium- molybdenum alloys (e.g., U S: N06625 such as INCONEL® 625, U S: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt- chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel- cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium- molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material.

As alluded to herein, within the family of commercially available nickel- titanium or nitinol alloys, is a category designated "linear elastic" or "non-super-elastic" which, although may be similar in chemistry to conventional shape memory and super elastic varieties, may exhibit distinct and useful mechanical properties. Linear elastic and/or non-super-elastic nitinol may be distinguished from super elastic nitinol in that the linear elastic and/or non-super-elastic nitinol does not display a substantial "superelastic plateau" or "flag region" in its stress/strain curve like super elastic nitinol does. Instead, in the linear elastic and/or non-super-elastic nitinol, as recoverable strain increases, the stress continues to increase in a substantially linear, or a somewhat, but not necessarily entirely linear relationship until plastic deformation begins or at least in a relationship that is more linear than the super elastic plateau and/or flag region that may be seen with super elastic nitinol. Thus, for the purposes of this disclosure linear elastic and/or non-super-elastic nitinol may also be termed "substantially" linear elastic and/or non-super-elastic nitinol.

In some cases, linear elastic and/or non-super-elastic nitinol may also be distinguishable from super elastic nitinol in that linear elastic and/or non-super-elastic nitinol may accept up to about 2-5% strain while remaining substantially elastic (e.g., before plastically deforming) whereas super elastic nitinol may accept up to about 8% strain before plastically deforming. Both of these materials can be distinguished from other linear elastic materials such as stainless steel (that can also be distinguished based on its composition), which may accept only about 0.2 to 0.44 percent strain before plastically deforming.

In some embodiments, the linear elastic and/or non-super-elastic nickel- titanium alloy is an alloy that does not show any martensite/austenite phase changes that are detectable by differential scanning calorimetry (DSC) and dynamic metal thermal analysis (DMTA) analysis over a large temperature range. For example, in some embodiments, there may be no martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about -60 degrees Celsius (°C) to about 120 °C in the linear elastic and/or non-super-elastic nickel -titanium alloy. The mechanical bending properties of such material may therefore be generally inert to the effect of temperature over this very broad range of temperature. In some embodiments, the mechanical bending properties of the linear elastic and/or non-super-elastic nickel- titanium alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature, for example, in that they do not display a super-elastic plateau and/or flag region. In other words, across a broad temperature range, the linear elastic and/or non-super-elastic nickel -titanium alloy maintains its linear elastic and/or non-super-elastic characteristics and/or properties.

In some embodiments, the linear elastic and/or non-super-elastic nickel- titanium alloy may be in the range of about 50 to about 60 weight percent nickel, with the remainder being essentially titanium. In some embodiments, the composition is in the range of about 54 to about 57 weight percent nickel. One example of a suitable nickel-titanium alloy is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Other suitable materials may include ULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available from Toyota). In some other embodiments, a superelastic alloy, for example a superelastic nitinol can be used to achieve desired properties.

In at least some embodiments, portions or all of the delivery system 12 and/or the medical implant 16, and/or components thereof, may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of the medical device system 10 in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the medical device system 10 to achieve the same result.

In some embodiments, a degree of Magnetic Resonance Imaging (MRI) compatibility is imparted into the medical device system 10. For example, the delivery system 12 and/or the medical implant 16, and/or components or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (i.e., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. The delivery system 12 and/or the medical implant 16, or portions thereof, may also be made from a material that the MRI machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium- molybdenum alloys (e.g., UNS : R30035 such as MP35-N® and the like), nitinol, and the like, and others.

In some embodiments, an exterior surface of the medical device system 10 (including, for example, an exterior surface of the delivery system 12) may be sandblasted, beadblasted, sodium bicarbonate-blasted, electropolished, etc. In these as well as in some other embodiments, a coating, for example a lubricious, a hydrophilic, a protective, or other type of coating may be applied over portions or all of the sheath, or in embodiments without a sheath over portion of the delivery system 12, or other portions of the medical device system 10. Alternatively, the sheath may comprise a lubricious, hydrophilic, protective, or other type of coating. Hydrophobic coatings such as fluoropolymers provide a dry lubricity which improves device handling and device exchanges. Lubricious coatings improve steerability and improve lesion crossing capability. Suitable lubricious polymers are well known in the art and may include silicone and the like, hydrophilic polymers such as high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics, algins, saccharides, caprolactones, and the like, and mixtures and combinations thereof. Hydrophilic polymers may be blended among themselves or with formulated amounts of water insoluble compounds (including some polymers) to yield coatings with suitable lubricity, bonding, and solubility.

The coating and/or sheath may be formed, for example, by coating, extrusion, co-extrusion, interrupted layer co-extrusion (ILC), or fusing several segments end-to- end. The layer may have a uniform stiffness or a gradual reduction in stiffness from the proximal end to the distal end thereof. The gradual reduction in stiffness may be continuous as by ILC or may be stepped as by fusing together separate extruded tubular segments. The outer layer may be impregnated with a radiopaque filler material to facilitate radiographic visualization. Those skilled in the art will recognize that these materials can vary widely without deviating from the scope of the present invention.

It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The invention's scope is, of course, defined in the language in which the appended claims are expressed.