Prosthetic Heart Valve Delivery System: Ball-Slide Attachment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.8. Application No. 17/158475, filed January 26, 2021 and entitled PROSTHETIC HEART VALVE DELIVERY SYSTEM: BALL-SLIDE ATTACHMENT and U.S. Provisional Application No. 62/968,216, filed January 31, 2020 and entitled PROSTHETIC HEART VALVE DELIVERY SYSTEM: BALL SLIDE ATT ACHMENT, the entirety of which is hereby incorporated by reference,

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR

DEVELOPMENT

[0001] Not Applicable

BACKGROUND OF THE INVENTION

[0002] FIELD OF THE INVENTION

[0003] The Invention relates to devices and methods for implanting devices within a heart chamber.

[0004] DESCRIPTION OF THE RELATED ART

Stents in general, and prosthetic cardiac valve and left atrial appendage occluding devices specifically, are well known in the art. The native heart valves, e.g., aortic, pulmonary, tricuspid and mitral valves, are critical in assuring the forward-only flow of an adequate supply of blood through the cardiovascular system. These heart valves may lose functionality as a result of, inter alia, congenital, inflammatory, infectious diseases or conditions. Early interventions repaired or replaced the dysfunctional valve(s) during open heart surgery. More recently, besides the open heart surgical approach discussed above, gaining access to the valve of interest may be achieved percutaneously via one of at least the following known access routes: transapical; transfemoral; transatrial; and transsepial delivery techniques, collectively transcatheter techniques.

[0005] Generally, in a transcatheter technique, the prosthetic valve is mounted within a stented frame that is capable of achieving collapsed and expanded states. The device is collapsed and advanced through a sheath or delivery catheter positioned in a blood vessel of the patient until reaching the implantation site. The stented frame is generally released from the catheter or sheath and, by a variety of means, expanded with the valve to the expanded functional size and orientation within the heart. One of the key issues is ease of delivery of the prosthetic valve, including the stent frame and valve in all access routes, including but not limited to transapical delivery. More specifically, it would be advantageous to have an improved delivery system for attaching, loading, translating, delivering, repositioning and resheathing and deploying an expandable stent to, and within, the subject heart chamber. The present invention addresses these, inter alia, issues.

[0006] DESCRIPTION OF THE RELATED ART

[0007] The human heart comprises four chambers and four heart valves that assist in the forward (antegrade) flow of blood through the heart. The chambers include the left atrium, left ventricle, right atrium and right ventricle. The four heart valves include the mitral valve, the tricuspid valve, the aortic valve and the pulmonary valve. See generally Figure 1.

[0008] The mitral valve is located between the left atrium and left ventricle and helps control the flow _' of blood from the left atrium to the left ventricle by acting as a one-way valve to prevent backflow into the left atrium. Similarly, the tricuspid valve is located between the right atrium and the right ventricle, while the aortic valve and the pulmonary valve are semilunar valves located in arteries flowing blood away from the heart. The valves are all one-way valves, with leaflets that open to allow' forward (antegrade) blood flow'. The normally functioning valve leaflets close under the pressure exerted by reverse blood to prevent backflow' (retrograde) of the blood into the chamber it just flowed out of. For example, the mitral valve when working properly provides a one-way valving between the left atrium and the left ventricle, opening to allow antegrade flow from the left atrium to the left ventricle and closing to prevent retrograde flow from the left ventricle into the left atrium. This retrograde flow, when present, is known as mitral regurgitation or mitral valve regurgitation. [0009] Native heart valves may be, or become, dysfunctional for a variety of reasons and/or conditions including but not limited to disease, trauma, congenital malformations, and aging. These types of conditions may cause the valve structure to fail to close properly resulting in regurgitant retrograde flow of blood from the left ventricle to the left atrium in the case of a mitral valve failure.

[0010] Mitral valve regurgitation is a specific problem resulting from a dysfunctional mitral valve that allows at least some retrograde blood flow back into the left atrium from the right atrium. In some cases, the dysfunction results from mitral valve leaflet(s) that prolapse up into the left atrial chamber, i.e., above the upper surface of the annulus instead of connecting or coupling to block retrograde flow. This backflow of blood places a burden on the left ventricle with a volume load that may lead to a series of left ventricular compensatory adaptations and adjustments, including remodeling of the ventricular chamber size and shape, that vary considerably during the prolonged clinical course of mitral regurgitation.

[0011] Regurgitation can be a problem with native heart valves generally, including tricuspid, aortic and pulmonary valves as well as mitral valves.

[0012] Native heart valves generally, e.g., mitral valves, therefore, may require functional repair and/or assistance, including a partial or complete replacement. Such intervention may take several forms including open heart surgery and open heart implantation of a replacement heart valve. See e.g,, U.S. Pat. No. 4,106,129 (Carpentier), for a procedure that is highly invasive, fraught with patient risks, and requiring not only an extended hospitalization but also a highly painful recovery period.

[0013] Less invasive methods and devices for replacing a dysfunctional heart valve are also known and involve percutaneous access and catheter-facilitated delivery of the replacement valve. Most of these solutions involve a replacement heart valve attached to a structural support such as a stent, commonly known in the art, or other form of ware network designed to expand upon release from a delivery catheter. See, e.g., U.S. Pat. No. 3,657,744 (Ersek); U.S. Pat. No. 5,411,552 (Andersen). The self-expansion variants of the supporting stent assist in positioning the valve, and holding the expanded device in position, within the subject heart chamber or vessel. This self-expanded form also presents problems when, as is often the case, the device is not properly positioned in the first positioning attempt and, therefore, must be recaptured and positionally adjusted. This recapturing process in the case of a fully, or even partially, expanded device requires re-collapsing the device to a point that allows the operator to retract the collapsed device back into a delivery sheath or catheter, adjust the inbound position for the device and then re-expand to the proper position by redeploying the positionally-adjusted device distally out of the delivery sheath or catheter. Collapsing the already expanded device is difficult because the expanded stent or wire network is generally designed to achieve the expanded state which also resists contractive or collapsing forces.

[0014] Besides the open heart surgical approach discussed above, gaining access to the valve of interest is achieved percutaneously via one of at least the following known access routes: transapical; transfemoral; transatrial; transaortic; and transseptal delivery techniques.

[0015] Generally, the art is focused on systems and methods that, using one of the above- described known access routes, allow a partial delivery of the collapsed valve device, wherein one end of the device is released from a delivery sheath or catheter and expanded for an initial positioning followed by full release and expansion when proper positioning is achieved. See , e.g., U.S. Pat. Nos. 8,852,271 (Murray, III); 8,747,459 (Nguyen); 8,814,931 (Wang); 9,402,720 (Richter); 8,986,372 (Murray, III); and 9,277,991 (Salahieh); and U.S. Pat. Pub. Nos. 2015/0272731 (Race hint); and 2016/0235531 (Ciobanu).

[0016] In addition, known “replacement” prosthetic heart valves are intended for full replacement of the native heart valve. Therefore, these replacement heart valves physically engage tissue within the annular throat, i.e,, below the annular plane and upper annular surface, and/or valve leaflets, thereby eliminating all remaining functionality of the native valve and making the patient completely reliant on the replacement valve. Generally speaking, it is a preferred solution that maintains and/or retains the native function of a heart valve, thus supplementation of the valve is preferred rather than full replacement. Obviously, there will be cases when native valve has either lost virtually complete functionality before the interventional implantation procedure, or the native valve continues to lose functionality after the implantation procedure. The preferred solution is delivery and implantation of a valve device that will function both as an adjunctive and/or supplementary functional valve as well as be fully capable of replacing the native function of a valve that has lost, or will lose, most or all of its functionality. However, the inventive solutions described infra will apply generally to all types and forms of heart valve devices, unless otherwise specified. The present disclosure also applies, as the skilled artisan will recognize, to stents generally. [0017] Further, known solutions for, e.g,, the mitral valve replacement systems, devices and methods require 2-chamber solutions, i.e., there is involvement and engagement of the implanted replacement valve device in the left atrium and the left ventricle. Generally, these solutions include a radially expanding stent in the left atrium, with anchoring or tethering (disposed downward through the native annulus or annular throat) connected from the stent device down through the annular throat, with the sub-annular surface within the left ventricle, the left ventricular chordae tendineae and even into the left ventricle wall surface(s). See, e.g., the MitraClip ^® marketed by the Abbott Group and currently the only US approved repair device. With the MitraClip ^® ' a catheter containing the MitraClip ^® is inserted into the femoral vein. The device enters the heart through the inferior vena cava to the right atrium and delivered trans- septally. The MitraClip ^®* ' passes through the annulus into the left ventricle and sits below' the leaflets, dipping the leaflets to decrease regurgitation.

[0018] Such 2-chamber and native annulus solutions are unnecessary bulky and therefore more difficult to deliver and to position/recapture/reposition from a strictly structural perspective. Further, the 2-chamber solutions present difficulties in terms of making the ventricular anchoring and/or tethering connections required to hold position. Moreover, these solutions interfere with the native valve functionality as described above because the device portions that are disposed within the left ventricle must be routed through the native annulus and/or annular throat and native mitral valve, thereby disrupting any remaining coaptation capability of the native leaflets. In addition, the 2-chamber solutions generally require an invasive anchoring of some of the native tissue, resulting in unnecessary trauma and potential complication.

[0019] It will be further recognized that the 2-chamber mitral valve solutions require sub-annular and/or ventricular engagement with anchors, tethers and the like precisely because the atrial portion of the device fails to adequately anchor itself to the atrial chamber and/or upper portion of the annulus. Again, some of the embodiments, or portions thereof, described herein are readily applicable to single or 2-chamber solutions, unless otherwise indicated.

[0020] Finally, known prosthetic cardiac valves consist of two or three leaflets that are arranged to act as a one-way valve, permitting fluid flow therethrough in the antegrade direction while preventing retrograde flow. The native mitral valve is located retrostemally at the fourth costal cartilage, consisting of an anterior and posterior leaflet, chordae tendinae, papillary muscles, ventricular wall and annulus connected to the atria. Each native leaflet is supported by chordae tendinae that are attached to papillary muscles which become taut with each ventricular contraction preserving valvular competence. Both the anterior and posterior leaflets of the native valve are attached via primary, secondary and tertiary chordae to both the antero-lateral and posterio-medial papillary muscles. A disruption in either papillary muscle in the setting of myocardial injury, can result in dysfunction of either the anterior or posterior leaflet of the mitral valve. Other mechanisms may result in failure of one, or both of the native mitral leaflets. In the case of a single mitral valve leaflet failure, the regurgitation may take the form of a noncentral, eccentric jet of blood back into the left atrium. Other leaflet failures may comprise a more centralized regurgitation jet. Known prosthetic valve replacements generally comprise leaflets which are arranged to mimic the native valve structure, which may over time become susceptible to similar regurgitation outcomes.

[0021] The applications for collapsible and expandable stents are not limited to prosthetic heart valve implants. Vascular stents are commonly used and are generally collapsible to facilitate delivery through the lumen of a delivery catheter to the working site where the stent is translated out of the lumen of the catheter and it is expanded, either by a self-expanding means or through an expanding mechanism such as, inter alia, an expandable balloon.

[0022] As discussed above, known delivery methods and devices comprise expandable prosthetic valve stents and vascular stents that are collapsed during delivery via a delivery catheter. Some issues with known systems, devices and methods include ease of attaching an operator-manipulatahle iether(s) to the stent for: loading and/or collapsing the expandable stent into a delivery catheter or sheath, translating the collapsed stent along the delivery catheter or sheath, delivering the expandable stent into the subject heart chamber, repositioning the expandable stent as necessary within the subject heart chamber, recapturing or resheathing the expandable stent within the delivery catheter or sheath if needed, and deploying the expandable stent to, and within, the subject heart chamber.

[§023] BRIEF SUMMARY OF THE INVENTION

[§§24] Systems, devices and methods for attaching an opera tor-manipulatable tetheris) to the stent for: loading and/or collapsing the expandable stent into a delivery catheter or sheath, translating the collapsed stent along the delivery catheter or sheath, delivering the expandable stent into the subject heart chamber, repositioning the expandable stent as necessary’ within the subject heart chamber, recapturing or resheathing the expandable stent within the delivery catheter or sheath if needed, and deploying the expandable stent to, and within, the subject heart chamber. The delivery system embodiments described herein apply to single chamber prosthetic heart valves as well as prosthetic heart valves that require anchoring outside of a single chamber. [0025] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0026] Figure 1 illustrates certain features of the heart in cross-section.

[0027] Figure 2 illustrates a perspective view of an exemplary stent.

[0028] Figure 3A illustrates a bottom view of one embodiment of a transition section of the exemplary stent of Fig. 2.

[0029] Figure 3B illustrates a bottom view of one embodiment of a transition section of the exemplary stent of Fig. 2.

[0030] Figure 3C illustrates a bottom view of one embodiment of a transition section of the exemplary stent of Fig. 2.

[0031] Figure 4 illustrates one embodiment of an attachment feature defined in an exemplary stent.

[0032] Figure 5A illustrates one embodiment of an attachment feature defined in a transition section of the exemplary stent of Fig. 2.

[0033] Figure 5B illustrates one embodiment comprising three attachment features defined in a transition section of the exemplary stent of Fig. 2.

[0034] Figure 6A illustrates one embodiment of a wire with distal ball.

[0035] Figure 6B illustrates one embodiment of a notched tube for slklingly receiving the wire with distal ball of Figure 6A.

[0036] Figure 6C illustrates one embodiment of an outer tube for receiving the notched tube of Figure 6B.

[0037] Figure 6D illustrates one embodiment of an assembled tether comprising the wire with distal ball, notched tube and outer tube of Figs. 6A-6C.

[0038] Figure 7 A illustrates one embodiment of the assembled tether with the ball in a partially retracted position. [0039] Figure 7B illustrates one embodiment of the assembled tether in a release position.

[0040] Figure 7C illustrates one embodiment of the assembled tether in a fully retracted position.

[0041] Figure 8 illustrates one embodiment of three spaced-apart tether assemblies extending distally from a delivery catheter or sheath.

[0042] Figure 9 illustrates one embodiment of three spaced-apart tether assemblies attached to three attachment features defined in a transition section of the exemplary stent of Fig. 2.

[0043] Figure 10A illustrates three exemplary tether assemblies attached to three attachment features of an exemplary stent frame, without displacement from a longitudinal axis.

[0044] Figure 10B illustrates three exemplary tether assemblies attached to three attachment features of an exemplary stent frame with displacement in a first direction relative to a longitudinal axis.

[0045] Figure IOC illustrates three exemplary tether assemblies attached to three attachment features of an exemplary stent frame with displacement in a second direction relative to a longitudinal axis.

[0046] Figure 11 A illustrates an exemplary handle and mechanism for adjusting (decreasing) the extension of each tether assembly distally from the distal end of the delivery catheter or sheath.

[0047] Figure 11B illustrates an exemplary handle and mechanism for adjusting (increasing) the extension of each tether assembly distally from the distal end of the delivery catheter or sheath.

[0048] Figure 12A illustrates an exemplary handle and mechanism for releasing one of the tether assemblies from attachment to the exemplary attachment features of the stent.

[0049] Figure 12B illustrates an exemplary handle and mechanism for releasing one of the tether assemblies from attachment to the exemplary attachment features of the stent.

DETAILED DESCRIPTION OF THE INVENTION

[0050] Generally, various embodiments of the present invention are directed to devices and methods for attaching an operator-manipulatable tether(s) to the stent for: loading and/or collapsing the expandable stent into a delivery catheter or sheath, translating the collapsed stent along the delivery catheter or sheath, delivering the expandable stent into the subject heart chamber, repositioning the expandable stent as necessary within the subject heart chamber, recapturing or resheathing the expandable stent within the deli very catheter or sheath if needed, and deploying the expandable stent to, and within, the subject heart chamber.

[0051] The support structure or stent has multiple functions to aid with the treatment of cardiac valve regurgitation (mitral or tricuspid). These functions include its function as a scaffold for the functioning prosthetic valve, apposition to the atrial anatomy, optimized radial force for compliance with atrial distension, ability to load and deploy from a minimally invasive delivery system, and geometry to support with mitigating against paravalvular leak (PVL). The design features of the stent are adapted to meet one or more of the functions identified above. Specific design features and attributes for exemplary stents are discussed in detail below to assist in understanding of the utility of the funneling loading device and related methods. As the skilled artisan will recognize, the invention is not limited to prosthetic heart valves comprising stent support structures but may also be applied to collapsible and expandable stents such as commonly used for intravascular' procedures. In addition, the skilled artisan will recognize the utility of the disclosed inventions for use in implanting certain exemplary embodiment stent design concepts that are intended to support minimally invasive procedures for the treatment of valvular regurgitation or other dysfunction in at least mitral, tricuspid, and aortic valves.

[0052] The stents may be self-expandable (e.g. nitinol or similar materials) or balloon expandable (e.g. cobalt chromium or similar materials). The stents are typically made of cells that may be open celled diamond like structures or continuous structures that have a working cell element. The stents may also be constructed using tubing, wires, braids or similar structures. Exemplary stent transition sections are described below.

[0053] With reference now to Figures 2-3C, one embodiment of an exemplary expandable stent 100 for use with the present invention comprises an outer section 102 - that may generally be circular though need not he a perfectly round circular structure when fully and/or partially expanded - and an inner valve support section 104 - which may be cylindrical but need not be a constant diameter cylinder and is adapted to support and retain prosthetic valve leaflets (not showii in Fig. 2) within the inner valve support section 104, most preferably at a point that located above the native annulus, e.g., the mitral valve annulus, though other attachment points for the prosthetic leaflets are within the scope of the present invention. Further, as discussed above, the stent 100 may be configured to supplement and/or replace the function of the tricuspid valve. A preferred construction comprises the prosthetic leaflets disposed above the native leaflets, wherein the prosthetic leaflets are attached and spaced sufficiently away from (above) the native leaflets so as to not physically interfere or interact with the native leaflets. However, certain embodiments contemplate some interaction with the native leaflets.

[0054] Individual cells Co forming the outer section 102 of stent 100 are visible in Figure 2 as open cell regions defined by the material used to form the exemplary expandable stent 100. [0055] Individual cells Ci forming the inner valve support section 104 are also illustrated as open cells regions formed within an inner region R defined by outer section 102, wherein the inner valve support section extends radially upward into the inner region R. As shown, individual cells Ci are of a different size, and may comprise a different shape, than that of individual cells Co.

[0056] The region of stent 100 that facilitates the radially inward transition of the stent 100 from the outer section 102 to the inner section 104 of the stent 100 is the transition section or cell region 106. Transition ceil region 106 may comprise cells Cx that may comprise a different size and/or shape that either the outer section cells Co and/or the inner section cells Ci. The outer and/or inner regions 102, 104, and/or transition cel l region 106 of the stent 100 may be constructed from one continuous structure or may combine two or more structures to achieve intended design goals. Transition cell region 106 comprises generally a radially upward turn to allow the inner valve support section 104 to reside within the inner region 102 as shown in Fig.

2. In some embodiments, the lower portion of inner valve support section 104, that is the portion of the inner valve support section 104 that is in connection with the cells C _T of transition cell region 106 may also comprise a curving shape to facilitate and/or complete the radially upward turn into the inner region 102.

[0057] The geometry and/or shape of the transition cells C _T may be substantially straight segments when expanded as in Figure 3A below or may, as shown in Figure 3B, incorporate an offset or a twist in the stent cell pattern when expanded to allow for a controlled compression of the stent. Exemplary cross-sectional geometry of the transition cell region 106 viewed from the bottom of stent 100 is represented schematically in Figures 3A and 3B.

[0058] This transition cell region 106 of the stent 100 may be a strut, completed cell section or a partial cell section. The transition cell region 106 may have any number of struts (minimum of 3) or cell sections as generally required to meet design needs. Transition cells Cx or stmts may be evenly spaced and formed by substantially straight and equally spaced apart struts 108 as shown in Fig. 3 A, that extend away from the inner valve support section 104 with equal angles a on both sides of the stmt 108 and equal angles b on both sides of strut 108 with respect to its intersection or integration with outer support section 102,

[0059] In one embodiment, the struts 108 of transition section 106 may be straight as in Figure 3A, but with non-equal angles relative to the inner valve support section 104 and outer support section 102 as shown in Figure 3C. There, the straight struts 108 are slanted so that a smaller angle a and a larger angle a’ are provided relative to the inner valve support section 104. Similarly, a smaller angle b’ and a larger angle b are provided relative to the outer support section 102. This allows a compressed nesting of the slanted struts 108 of transition section 106.

[0060] In another preferred embodiment, the transition cell region 106 may comprise transition cell struts 108’ that comprise transition cells C _T that are formed by struts 108’ having an offset, i.e., not straight, are twisted and/or curvilinear. The degree of offset and/or twist and/or curvature of the struts 108’, and therefore the size and/or shape of the resultant expanded cells C _T may be varied dependent on the number of cells/struts in the transition cell region 106, packing density when the stent is collapsed, and stress/strain distribution limitations of the transition cell region 106.

[0061] Turning now to Figure 4, an attachment feature 402 is defined along one of the struts 108 as described above in Figures 2-3B, preferably within the transition cell region 106 of the expandable stent 102. However, the skilled artisan will recognize that attachment feature 402 may also be defined along strut(s) that are not within the transition cell region 106. In addition, the attachment feature 402 is shown as circular, but other shapes are certainly possible and within the scope of the present invention, In addition, attachment feature 402 may be defined on a strut of a stent frame that is on a downstream (of the normal blood flow within the prosthetic heart valve) side of the stent frame when implanted. Alternatively, attachment feature 402 may be defined on the lowermost downstream strut of the prosthetic heart valve frame.

[0062] Figure 5A shows an exemplary circular attachment feature 402 disposed and defined along a stent strut and Figure 5B illustrates the locations around the transition cell region 106 of exemplary expandable stent 102 for three (3) of the attachment features 402. As shown, there is a substantially equal spacing or separation between adjacent attachment features 402 along and/or around the transition cell region 106. The skilled artisan will recognize the non-equal spacings or separations between the locations of the attachment features 402 may also he employed. In addition, at least one attachment feature 402 may be used. It is preferable to have at least two, and more preferable to have at least three, attachment features 402 defined as described herein.

[0063] Turning now to Figures 6A-7A, one embodiment of a tether assembly 410 that is operationally connected at a proximal end to an operational handle, as will be discussed further, is illustrated. Tether assembly 410 further comprises an outer tube 404, a notched tube 406 and a wire with distal enlarged element 408, wherein tether assembly comprises a length that enables proximal connection with handle H and sufficient extension length from the distal end of a delivery catheter or sheath to facilitate, inter alia, translation and deployment of the subject prosthetic heart valve as will be further discussed herein. The wire distal enlarged element 408 is not restricted to a wire and may also include equivalent structures such as but not limited to a tube, a rod that may be hollow or solid, and the like.

[0064] Outer tube 404 is provided having a lumen L1 therethrough. Notched tube 406 is sized to be slidingly received within lumen LI and comprises distal flexible tabs 407 extending distally from notched tube lumen L2, as shown.

[0065] Wire with distal enlarged element 408, wherein the enlarged distal element 409 is shown as a bail, is adapted to be slidingly received within lumen L2, creating a nested arrangement as shown in Fig. 6D for the tether assembly 410.

[0066] Figures 7A-7C illustrate the operation and relationship of the components of tether assembly 410 during certain steps of the prosthetic heart valve loading, translating, repositioning, recapture, deployment and release during the implanting process.

[0067] Figure 7A shows the distal enlarged element 409 of the wire with distal enlarged distal element 408 pulled proximal] y back into the distal flexible tabs 407 of the notched tube 406, deforming the tabs 407 to create a compression or friction fit therein. In addition, the distance between the tabs 407 when deformed as shown is greater than the distance therebetween when the hall 409 is not interposed between the tabs 407. This arrangement enables the enlarged distal element, as shown a ball, 409, having a diameter that is smaller than a smallest diameter of the attachment feature 402, and the distal flexible tabs 407, also having a maximum non-deformed length between the tabs 407 that is smaller than a smallest diameter of the attachment feature 402, to be inserted through the attachment feature. The insertion position is as shown in Fig. 6D, with distal enlarged element 409, shown as a hall, positioned distal to the distal flexible tabs 407. When the distal enlarged element 409 and distal flexible tabs 407 are inserted through attachment feature 402, the operator may then retract proxirnally the wire with enlarged distal element 408 as shown in Fig. 7A to engage and deform the distal flexible table 407 with distal enlarged element 409, causing the distance between the tabs 407 to increase to a length that is now' greater than the diameter of the attachment feature, thereby attaching the tether assembly 410 to the stent 102, preferably at the transition section as discussed above. This process step is repeated for each of the at least one tether assembly 410 to attach the tether assembly(ies) 410 to the stent 102.

[0068] The skilled artisan will appreciate that, though a preferred embodiment comprises a ball shaped distal enlarged element 409 and a circular attachment feature 402, other shapes may be used for the bail-shaped distal enlarged element 409 and/or attachment feature 402. Some of these shapes may be complementary, e.g., a square element substituting for the distal ball -shaped distal enlarged element 409 and a square attachment feature 402. How'ever, complementary features are not required so long as the distal element, e.g. the illustrated ball 409, fits through the attachment feature 402 and can be pulled distally to deform the flexible distal tabs 407 to achieve atachment.

[0069] The skilled artisan will also appreciate that a paravalvular leakage mitigation skirt or fabric may cover at least part of the expandable stent 102, including but not limited to the transition cell region. In such a case, the tether assembly 410 may extend through the skirt or fabric to reach and attach to, and release from, the atachment feature 402.

[0070] Thus attached to the stent frame, the tether assembly (ies) 410 may be used to collapse the self-expanding stent frame 102 into the proximal end of the lumen of a delivery catheter or sheath and assist in translating the collapsed stent frame 102 distally through the delivery catheter or sheath to the distal end of the delivery catheter of sheath which is pre-positioned at the heart chamber of interest. At this point, the collapsed stent frame 102 is at least partially released from the delivery catheter or sheath and begins to self-expand. The attached tether assembiy(ies) 410 may be used to assist in this process by manipulating the tether assembly(ies) 410 to move the at least partially expanded stent frame 102 into proper position within the subject heart chamber. In certain cases, it may be advantageous to reposition the at least partially expanded stent frame comprising a prosthetic heart valve by pulling proximally one or more of the tether assembly(ies) 41(3 to move the stent frame 102 in a desired direction and into a desired attitude within the heart valve, relative to anatomical landmarks. Figures 10 A- IOC illustrate one embodiment comprising three tether assemblies 410 wherein Fig. 10 A is a default position and the stent frame 102 is substantially symmetrically aligned with the longitudinal axis of the delivery sheath. Figures 10B and IOC show the ability of pulling (or pushing) one or more tether assembly(ies) 410 to cause the connected stent frame 102 to move away from the symmetrical alignment of the longitudinal axis to take on an asymmetrical attitude to assist in positioning and deploying the stent frame 102.

[0071] Figures 11A and 11B, and 12A and 12B, provide embodiments of an operating handle H to which the distal end of each tether assembly 410 is connected. As indicated, the length of extension of the tether assembly 410 away from the distal end of the delivery sheath may be manipulated by moving the attached push/pull and release mechanism 430 proximally or distally at the handle H. This may be done as a combined set of tether assemblies, or individual tether assemblies 410 may be selected for selective lengthening (pushing it distally) or shortening (pulling it proximally), relative to the other tether assembly(ies) 410, and/or the components of each tether assembly 410 comprising the outer tube 404, the notched tube 406 and the wire with enlarged distal element 4(38 may each be pushed proximally and/or pulled distally independently. Each tether assembly 410 has its own length and release mechanism 430 attached to handle H. [0072] Each push/pull and release mechanism 430 Farther comprises a lever that may be locked and unlocked and allows manipulation of the individual components of the tether assembly 410. When locked, the associated tether assembly 410 is attached to an attachment feature 402 as described above. Releasing the tether assembly 410 from the attachment feature 402 is achieved by, as in Figures 12A-12B, by unlocking a lever (actuating the lever as shown), and then pulling the unlocked portion of the assembly distally, i.e,, pulling distally the related component of the tether assembly, i.e., the notched tube 406, the wire with enlarged distal element 408) distally and out. of attached engagement with the attachment feature 402, It will be obvious now to the skilled artisan that this same mechanism 430 may be used to advance and/or retract the components of the tether assembly 410 to achieve attachment with, and/or release from, the attachment feature 402.

[0073] Figures 12A-12B provide a mechanism by which the tether assemblies 410 are individually released from the stent frame and retracted proximaliy as in Figures 7B and 7C. [0074] In some cases, it may be advantageous to at least partially recover, resheath and/or recapture the at least partially expanded stent frame 102 by pulling it proximaliy into the lumen of the delivery catheter or sheath, then reinitiating release and deployment steps.

[0075] When the stent frame comprising the prosthetic heart valve is properly positioned, as shown in Figures 7B and 7C, the enlarged distal element 409 of the wire with enlarged distal element 408 is pushed distaily away from the distal flexible tabs 407, so that the distal flexible tabs 407 return to their undeformed shape which allows the notched tube 406 and wire with distal enlarged element 408 to be withdrawn from the attachment feature 402, thereby disconnecting the tether assembly 410 from the stent frame 102. Once each provided tether assembly 410 is disconnected from the stent frame 102, the tether assembly(ies) 410 may be withdrawn from the heart chamber.

[0076] Figure 8 and 9 provide additional detail for a preferred embodiment comprising three (3) tether assemblies (410).

[0077] As discussed, a preferred access route for the disclosed delivery system comprises a transapical approach, though all other delivery access routes may be successfully navigated using the disclosed invention(s).

[0078] The description of the invention and its applications as set forth herein is illustrative and is not intended to limit the scope of the invention. Features of various embodiments may be combined with other embodiments within the contemplation of this invention. Variations and modifications of the embodiments disclosed herein are possible, and practical alternatives to and equivalents of the various elements of the embodiments would be understood to those of ordinary skill in the art upon study of this patent document. These and other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.