Patent ID: 12213661

DETAILED DESCRIPTION

I. Introduction

A. Cardiac Physiology

The left ventricle (LV) of a normal heart H in systole is illustrated inFIG.1. The left ventricle (LV) is contracting and blood flows outwardly through the tricuspid (aortic) valve (AV) in the direction of the arrows. Back flow of blood or “regurgitation” through the mitral valve (MV) is prevented since the mitral valve is configured as a “check valve” which prevents back flow when pressure in the left ventricle is higher than that in the left atrium (LA). The mitral valve (MV) comprises a pair of leaflets having free edges (FE) which meet evenly to close, as illustrated inFIG.1. The opposite ends of the leaflets (LF) are attached to the surrounding heart structure along an annular region referred to as the annulus (AN). The free edges (FE) of the leaflets (LF) are secured to the lower portions of the left ventricle LV through chordae tendinae (CT) (referred to hereinafter as the chordae) which include a plurality of branching tendons secured over the lower surfaces of each of the valve leaflets (LF). The chordae (CT) in turn, are attached to the papillary muscles (PM) which extend upwardly from the lower portions of the left ventricle and intraventricular septum IVS.

A number of structural defects in the heart can cause mitral valve regurgitation. Regurgitation occurs when the valve leaflets do not close properly allowing leakage from the ventricle into the atrium. As shown inFIG.2A, the free edges of the anterior and posterior leaflets normally meet along a line of coaptation (C). An example of a defect causing regurgitation is shown in FIG.2B. Here an enlargement of the heart causes the mitral annulus to become enlarged, making it impossible for the free edges (FE) to meet during systole. This results in a gap (G) which allows blood to leak through the valve during ventricular systole. Ruptured or elongated chordae can also cause a valve leaflet to prolapse since inadequate tension is transmitted to the leaflet via the chordae. While the other leaflet maintains a normal profile, the two valve leaflets do not properly meet and leakage from the left ventricle into the left atrium will occur. Such regurgitation can also occur in patients who have suffered ischemic heart disease where the left ventricle does not contract sufficiently to effect proper closure.

II. General Overview of Mitral Valve Fixation Technology

Fixation devices are used for grasping, approximating and fixating tissues such as valve leaflets to treat cardiac valve regurgitation, particularly mitral valve regurgitation. The fixation devices may also provide features that allow repositioning and removal of the device if so desired, particularly in areas where removal may be hindered by anatomical features such as chordae CT. Such removal would allow the surgeon to reapproach the valve in a new manner if so desired.

Grasping will preferably be atraumatic providing a number of benefits. By atraumatic, it is meant that the devices and methods may be applied to the valve leaflets and then removed without causing any significant clinical impairment of leaflet structure or function. The leaflets and valve continue to function substantially the same as before the fixation devices are applied. Thus, some minor penetration or denting of the leaflets may occur using the devices while still meeting the definition of “atraumatic.” Similarly, during disabling or removal of the fixation device, a small portion of the leaflet(s) may be cut around the edges of the fixation device. Such atraumatic installation, disabling, or removal enables the devices to be applied to a diseased valve and, if desired, removed or repositioned without having negatively affected valve function. In addition, it will be understood that in some cases it may be necessary or desirable to pierce or otherwise permanently affect the leaflets during either grasping, fixing and/or removal. In some cases, grasping and fixation may be accomplished by a single device.

The fixation devices may rely upon the use of an interventional tool that is positioned near a desired treatment site and used to grasp the target tissue. In endovascular applications, the interventional tool is typically an interventional catheter. In surgical applications, the interventional tool is typically an interventional instrument. Fixation of the grasped tissue is accomplished by maintaining grasping with a portion of the interventional tool which is left behind as an implant. The fixation devices are well adapted for the repair of valves, especially cardiac valves such as the mitral valve.

Referring toFIG.3A, an interventional tool10, having a delivery device, such as a shaft12, and a fixation device14, is illustrated having approached the mitral valve MV from the atrial side and grasped the leaflets LF. The mitral valve may be accessed either surgically or by using endovascular techniques, and either by a retrograde approach through the ventricle or by an antegrade approach through the atrium, as described above. For illustration purposes, an antegrade approach is described.

The fixation device14is releasably attached to the shaft12of the interventional tool10at its distal end. When describing the devices of the invention herein, “proximal” shall mean the direction toward the end of the device to be manipulated by the user outside the patient's body, and “distal” shall mean the direction toward the working end of the device that is positioned at the treatment site and away from the user. With respect to the mitral valve, proximal shall refer to the atrial or upstream side of the valve leaflets and distal shall refer to the ventricular or downstream side of the valve leaflets.

The fixation device14typically comprises proximal elements16(or gripping elements) and distal elements18(or fixation elements) which protrude radially outward and are positionable on opposite sides of the leaflets LF as shown so as to capture or retain the leaflets therebetween. The proximal elements16are preferably comprised of cobalt chromium, nitinol or stainless steel, and the distal elements18are preferably comprised of cobalt chromium or stainless steel, however any suitable materials may be used. The fixation device14is coupleable to the shaft12by a coupling mechanism17. The coupling mechanism17allows the fixation device14to detach and be left behind as an implant to hold the leaflets together in the coapted position.

In some situations, it may be desired to reposition or remove the fixation device14after the proximal elements16, distal elements18, or both have been deployed to capture the leaflets LF. Such repositioning or removal may be desired for a variety of reasons, such as to reapproach the valve in an attempt to achieve better valve function, more optimal positioning of the device14on the leaflets, better purchase on the leaflets, to detangle the device14from surrounding tissue such as chordae, to exchange the device14with one having a different design, or to abort the fixation procedure, to name a few. To facilitate repositioning or removal of the fixation device14the distal elements18may be released and optionally inverted to a configuration suitable for withdrawal of the device14from the valve without tangling or interfering with or damaging the chordae, leaflets or other tissue. According to another embodiment, any of the endovascular methods described herein for disabling or removal of the fixation device may also be used.

FIG.3Billustrates inversion wherein the distal elements18are moveable in the direction of arrows40to an inverted position. Likewise, the proximal elements16may be raised, if desired. In the inverted position, the device14may be repositioned to a desired orientation wherein the distal elements may then be reverted to a grasping position against the leaflets as inFIG.3A. Alternatively, the fixation device14may be withdrawn (indicated by arrow42) from the leaflets as shown inFIG.3C. Such inversion reduces trauma to the leaflets and minimizes any entanglement of the device with surrounding tissues. Once the device14has been withdrawn through the valve leaflets, the proximal and distal elements may be moved to a closed position or configuration suitable for removal from the body or for reinsertion through the mitral valve.

FIG.4illustrates the position of the fixation device14in a desired orientation in relation to the leaflets LF. This is a short-axis view of the mitral valve MV from the atrial side, therefore, the proximal elements16are shown in solid line and the distal elements18are shown in dashed line. The proximal and distal elements16,18are positioned to be substantially perpendicular to the line of coaptation C. The device14may be moved roughly along the line of coaptation to the location of regurgitation. The leaflets LF are held in place so that during diastole, as shown inFIG.4, the leaflets LF remain in position between the elements16,18surrounded by openings or orifices O which result from the diastolic pressure gradient. Advantageously, leaflets LF are coapted such that their proximal or upstream surfaces are facing each other in a vertical orientation, parallel to the direction of blood flow through mitral valve MV. The upstream surfaces may be brought together so as to be in contact with one another or may be held slightly apart, but will preferably be maintained in the vertical orientation in which the upstream surfaces face each other at the point of coaptation. This simulates the double orifice geometry of a standard surgical bow-tie repair. Color Doppler echo will show if the regurgitation of the valve has been reduced. If the resulting mitral flow pattern is satisfactory, the leaflets may be fixed together in this orientation. If the resulting color Doppler image shows insufficient improvement in mitral regurgitation, the interventional tool10may be repositioned. This may be repeated until an optimal result is produced wherein the leaflets LF are held in place.

Once the leaflets are coapted in the desired arrangement, the fixation device14is then detached from the shaft12and left behind as an implant to hold the leaflets together in the coapted position. As mentioned previously, the fixation device14is coupled to the shaft12by a coupling mechanism17.FIGS.5A-5B,6A-6Billustrate examples of such coupling mechanisms.FIG.5Ashows an upper shaft20and a detachable lower shaft22which are interlocked at a joining line or mating surface24. The mating surface24may have any shape or curvature which will allow or facilitate interlocking and later detachment. A snuggly fitting outer sheath26is positioned over the shafts20,22to cover the mating surface24as shown.FIG.5Billustrates detachment of the lower shaft22from the upper shaft20. This is achieved by retracting the outer sheath26, so that the mating surface24is exposed, which allows the shafts20,22to separate.

Similarly,FIG.6Aillustrates a tubular upper shaft28and a detachable tubular lower shaft30which are interlocked at a mating surface32. Again, the mating surface32may have any shape or curvature which will allow or facilitate interlocking and later detachment. The tubular upper shaft28and tubular lower shaft30form an outer member having an axial channel. A snuggly fitting rod34or inner member is inserted through the tubular shafts28,30to bridge the mating surface32as shown.FIG.6Billustrates detachment of the lower shaft30from the upper shaft28. This is achieved by retracting the rod34to a position above the mating surface32which in turn allows the shafts28,30to separate.

The mating surface24(or mating surface32) is a sigmoid curve defining a male element and female element on upper shaft20(or upper shaft28) which interlock respectively with corresponding female and male elements on lower shaft22(or lower shaft30). Typically, the lower shaft is the coupling mechanism17of the fixation device14. Therefore, the shape of the mating surface selected will preferably provide at least some mating surfaces transverse to the axial axis of the mechanism19to facilitate application of compressive and tensile forces through the coupling mechanism17to the fixation device14, yet causing minimal interference when the fixation device14is to be released from the upper shaft. It will be appreciated that these coupling mechanisms are exemplary, and other coupling mechanisms could also be used.

A. Exemplary Fixation Device

FIG.7illustrates an exemplary fixation device14. Here, the fixation device14is shown coupled to a shaft12to form an interventional tool10. The fixation device14includes a coupling member19and a pair of opposed distal elements18. The distal elements18comprise elongate arms53, each arm having a proximal end52rotatably connected to the coupling member19and a free end54. The free ends54have a rounded shape to minimize interference with and trauma to surrounding tissue structures. Preferably, each free end54defines a curvature about two axes, one being an axis66perpendicular to longitudinal axis of arms53. Thus, the engagement surfaces50have a cupped or concave shape to the surface area in contact with tissue and to assist in grasping and holding the valve leaflets. This further allows arms53to nest around the shaft12in the closed position to minimize the profile of the device. Preferably, arms53are at least partially cupped or curved inwardly about their longitudinal axes66. Also, preferably, each free end54defines a curvature about an axis67perpendicular to axis66or the longitudinal axis of arms53. This curvature is a reverse curvature along the most distal portion of the free end54. Likewise, the longitudinal edges of the free ends54may flare outwardly. Both the reverse curvature and flaring minimize trauma to the tissue engaged therewith.

To be suitable for mitral valve repair, the transverse width across engagement surfaces50(which determines the width of tissue engaged) may be at least about 2 mm, usually 3-10 mm, and preferably about 4-6 mm. In some situations, a wider engagement is desired wherein the engagement surfaces50are larger, for example about 2 cm, or multiple fixation devices are used adjacent to each other. Arms53and engagement surfaces50are configured to engage a length of tissue of about 4-10 mm, and preferably about 6-8 mm along the longitudinal axis of arms53. Arms53further include a plurality of openings to enhance grip and to promote tissue ingrowth following implantation.

The valve leaflets are grasped between the distal elements18and proximal elements16. The proximal elements16may be flexible, resilient, and cantilevered from coupling member19. The proximal elements are preferably resiliently biased toward the distal elements. Each proximal element16is shaped and positioned to be at least partially recessed within the concavity of the distal element18when no tissue is present. When the fixation device14is in the open position, the proximal elements16are shaped such that each proximal element16is separated from the engagement surface50near the proximal end52of arm53and slopes toward the engagement surface50near the free end54with the free end of the proximal element contacting engagement surface50, as illustrated inFIG.7. This shape of the proximal elements16accommodates valve leaflets or other tissues of varying thicknesses.

Proximal elements16include a plurality of openings63and scalloped side edges61to increase grip on tissue. The proximal elements16optionally include frictional accessories, frictional features or grip-enhancing elements to assist in grasping and/or holding the leaflets. The frictional accessories may comprise barbs60having tapering pointed tips extending toward engagement surfaces50. Any suitable frictional accessories may be used, such as prongs, windings, bands, barbs, grooves, channels, bumps, surface roughening, sintering, high-friction pads, coverings, coatings or a combination of these. Optionally, magnets may be present in the proximal and/or distal elements. It may be appreciated that the mating surfaces will be made from or will include material of opposite magnetic charge to cause attraction by magnetic force. For example, the proximal elements and distal elements may each include magnetic material of opposite charge so that tissue is held under constant compression between the proximal and distal elements to facilitate faster healing and ingrowth of tissue. Also, the magnetic force may be used to draw the proximal elements16toward the distal elements18, in addition to or alternatively to biasing of the proximal elements toward the distal elements. This may assist in deployment of the proximal elements16. In another example, the distal elements18each include magnetic material of opposite charge so that tissue positioned between the distal elements18is held therebetween by magnetic force.

The proximal elements16may be covered with a fabric or other flexible material as described below to enhance grip and tissue ingrowth following implantation. Preferably, when fabrics or coverings are used in combination with barbs or other frictional features, such features will protrude through such fabric or other covering so as to contact any tissue engaged by proximal elements16.

Proximal elements16may be formed from metallic sheet of a spring-like material using a stamping operation which creates openings63, scalloped edges61and barbs60. Alternatively, proximal elements16could be comprised of a spring-like material or molded from a biocompatible polymer. Some types of frictional accessories may permanently alter or cause some trauma to the tissue engaged thereby, whereas other frictional accessories will be atraumatic and will not injure or otherwise affect the tissue in a clinically significant way. For example, in the case of barbs60, it has been demonstrated that following engagement of mitral valve leaflets by fixation device14, should the device later be removed during the procedure barbs60leave no significant permanent scarring or other impairment of the leaflet tissue and are thus considered atraumatic.

The fixation device14also includes an actuation mechanism58. The actuation mechanism58comprises two link members or legs68, each leg68having a first end70which is rotatably joined with one of the distal elements18at a riveted joint76and a second end72which is rotatably joined with a stud74. The legs68are preferably comprised of a rigid or semi-rigid metal or polymer such as Elgiloy®, cobalt chromium or stainless steel, however any suitable material may be used. While in the device illustrated both legs68are pinned to stud74by a single rivet78, it may be appreciated, however, that each leg68may be individually attached to the stud74by a separate rivet or pin. The stud74is joinable with an actuator rod64(not shown) which extends through the shaft12and is axially extendable and retractable to move the stud74and therefore the legs68which rotate the distal elements18between closed, open and inverted positions. Likewise, immobilization of the stud74holds the legs68in place and therefore holds the distal elements18in a desired position. The stud74may also be locked in place by a locking feature which will be further described in later sections.

There may be some mobility or flexibility in distal elements18and/or proximal elements16of the fixation device14in the closed position to enable these elements to move or flex with the opening or closing of the valve leaflets. This provides shock absorption and thereby reduces force on the leaflets and minimizes the possibility for tearing or other trauma to the leaflets. Such mobility or flexibility may be provided by using a flexible, resilient metal or polymer of appropriate thickness to construct the distal elements18. Also, the locking mechanism of the fixation device (described below) may be constructed of flexible materials to allow some slight movement of the proximal and distal elements even when locked. Further, the distal elements18can be connected to the coupling mechanism19or to actuation mechanism58by a mechanism that biases the distal element into the closed position (inwardly) but permits the arms to open slightly in response to forces exerted by the leaflets. For example, rather than being pinned at a single point, these components may be pinned through a slot that allows a small amount of translation of the pin in response to forces against the arms. A spring may be used to bias the pinned component toward one end of the slot.

FIGS.8A-8B,9A-9B,10A-10B,11A-11B, andFIGS.12-14illustrate various possible positions of the fixation device14ofFIG.7during introduction and placement of the device14within the body to perform a therapeutic procedure.FIG.8Aillustrates an interventional tool10delivered through a catheter86. It may be appreciated that the interventional tool10may take the form of a catheter, and likewise, the catheter86may take the form of a guide catheter or sheath. However, in this example the terms interventional tool10and catheter86will be used. The interventional tool10comprises a fixation device14coupled to a shaft12and the fixation device14is shown in the closed position.FIG.8Billustrates a device similar to the device ofFIG.8Ain a larger view. In the closed position, the opposed pair of distal elements18are positioned so that the engagement surfaces50face each other. Each distal element18comprises an elongate arm53having a cupped or concave shape so that together the aims53surround the shaft12and optionally contact each other on opposite sides of the shaft. This provides a low profile for the fixation device14which is readily passable through the catheter86and through any anatomical structures, such as the mitral valve. In addition,FIG.8Bfurther includes an actuation mechanism58. The actuation mechanism58comprises two legs68which are each movably coupled to a base69. The base69is joined with an actuator rod64which extends through the shaft12and is used to manipulate the fixation device14. The actuator rod64may attach directly to the actuation mechanism58, particularly the base69. However, the actuator rod64may alternatively attach to a stud74which in turn is attached to the base69. The stud74may be threaded so that the actuator rod64attaches to the stud74by a screw-type action. However, the rod64and stud74may be joined by any mechanism which is releasable to allow the fixation device14to be detached from shaft12.

FIGS.9A-9Billustrate the fixation device14in the open position. In the open position, the distal elements18are rotated so that the engagement surfaces50face a first direction. Distal advancement of the stud74relative to coupling member19by action of the actuator rod64applies force to the distal elements18which begin to rotate around joints76due to freedom of movement in this direction. Such rotation and movement of the distal elements18radially outward causes rotation of the legs68about joints80so that the legs68are directed slightly outwards. The stud74may be advanced to any desired distance correlating to a desired separation of the distal elements18. In the open position, engagement surfaces50are disposed at an acute angle relative to shaft12, and are preferably at an angle of between 90 and 180 degrees relative to each other. In the open position, the free ends54of arms53may have a span therebetween of about 10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm.

Proximal elements16are typically biased outwardly toward arms53. The proximal elements16may be moved inwardly toward the shaft12and held against the shaft12with the aid of proximal element lines90which can be in the form of sutures, wires, nitinol wire, rods, cables, polymeric lines, or other suitable structures. The proximal element lines90may be connected with the proximal elements16by threading the lines90in a variety of ways. When the proximal elements16have a loop shape, as shown inFIG.9A, the line90may pass through the loop and double back. When the proximal elements16have an elongate solid shape, as shown inFIG.9B, the line90may pass through one or more of the openings63in the element16. Further, a line loop48may be present on a proximal element16, also illustrated inFIG.9B, through which a proximal element line90may pass and double back. Such a line loop48may be useful to reduce friction on proximal element line90or when the proximal elements16are solid or devoid of other loops or openings through which the proximal element lines90may attach. A proximal element line90may attach to the proximal elements16by detachable means which would allow a single line90to be attached to a proximal element16without doubling back and would allow the single line90to be detached directly from the proximal element16when desired. Examples of such detachable means include hooks, snares, clips or breakable couplings, to name a few.

By applying sufficient tension to the proximal element line90, the detachable means may be detached from the proximal element16such as by breakage of the coupling. Other mechanisms for detachment may also be used. Similarly, a lock line92(FIG.16) may be attached and detached from a locking mechanism by similar detachable means.

In the open position, the fixation device14can engage the tissue which is to be approximated or treated. The device illustrated inFIGS.7-9Bis adapted for repair of the mitral valve using an antegrade approach from the left atrium. The interventional tool10is advanced through the mitral valve from the left atrium to the left ventricle. The distal elements18are oriented to be perpendicular to the line of coaptation and then positioned so that the engagement surfaces50contact the ventricular surface of the valve leaflets, thereby grasping the leaflets. The proximal elements16remain on the atrial side of the valve leaflets so that the leaflets lie between the proximal and distal elements. The proximal elements16have frictional accessories, such as barbs60which are directed toward the distal elements18. However, neither the proximal elements16nor the barbs60contact the leaflets at this time.

The interventional tool10may be repeatedly manipulated to reposition the fixation device14so that the leaflets are properly contacted or grasped at a desired location. Repositioning is achieved with the fixation device in the open position. In some instances, regurgitation may also be checked while the device14is in the open position. If regurgitation is not satisfactorily reduced, the device may be repositioned and regurgitation checked again until the desired results are achieved.

It may also be desired to invert the fixation device14to aid in repositioning or removal of the fixation device14.FIGS.10A-10Billustrate the fixation device14in the inverted position. By further advancement of stud74relative to coupling member19, the distal elements18are further rotated so that the engagement surfaces50face outwardly and free ends54point distally, with each arm53forming an obtuse angle relative to shaft12.

The angle between arms53is preferably in the range of about 270 to 360 degrees. Further advancement of the stud74further rotates the distal elements18around joints76. This rotation and movement of the distal elements18radially outward causes rotation of the legs68about joints80so that the legs68are returned toward their initial position, generally parallel to each other. The stud74may be advanced to any desired distance correlating to a desired inversion of the distal elements18. Preferably, in the fully inverted position, the span between free ends54is no more than about 20 mm, usually less than about 16 mm, and preferably about 12-14 mm. In this illustration, the proximal elements16remain positioned against the shaft12by exerting tension on the proximal element lines90. Thus, a relatively large space may be created between the elements16,18for repositioning. In addition, the inverted position allows withdrawal of the fixation device14through the valve while minimizing trauma to the leaflets. Engagement surfaces50provide an atraumatic surface for deflecting tissue as the fixation device is retracted proximally. Barbs60are angled slightly in the distal direction (away from the free ends of the proximal elements16), reducing the risk that the barbs will catch on or lacerate tissue as the fixation device is withdrawn.

Once the fixation device14has been positioned in a desired location against the valve leaflets, the leaflets may then be captured between the proximal elements16and the distal elements18.FIGS.11A-11Billustrate the fixation device14in such a position. Here, the proximal elements16are lowered toward the engagement surfaces50so that the leaflets are held therebetween. InFIG.11B, the proximal elements16are shown to include barbs60which may be used to provide atraumatic gripping of the leaflets. Alternatively, larger, more sharply pointed barbs or other penetration structures may be used to pierce the leaflets to more actively assist in holding them in place. This position is similar to the open position ofFIGS.9A-9B, however the proximal elements16are now lowered toward arms53by releasing tension on proximal element lines90to compress the leaflet tissue therebetween. At any time, the proximal elements16may be raised and the distal elements18adjusted or inverted to reposition the fixation device14, if regurgitation is not sufficiently reduced.

After the leaflets have been captured between the proximal and distal elements16,18in a desired arrangement, the distal elements18may be locked to hold the leaflets in this position or the fixation device14may be returned to or toward a closed position. Such locking will be described in a later section.FIG.12illustrates the fixation device14in the closed position wherein the leaflets (not shown) are captured and coapted. This is achieved by retraction of the stud74proximally relative to coupling member19so that the legs68of the actuation mechanism58apply an upwards force to the distal elements18which in turn rotate the distal elements18so that the engagement surfaces50again face one another. The released proximal elements16which are biased outwardly toward distal elements18are concurrently urged inwardly by the distal elements18. The fixation device14may then be locked to hold the leaflets in this closed position as described below.

As shown inFIG.13, the fixation device14may then be released from the shaft12. As mentioned, the fixation device14is releasably coupleable to the shaft12by coupling member19.FIG.13illustrates the coupling structure, a portion of the shaft12to which the coupling member19of the fixation device14attaches. As shown, the proximal element lines90may remain attached to the proximal elements16following detachment from shaft12to function as a tether to keep the fixation device14connected with the catheter86. Optionally, a separate tether coupled between shaft12and fixation device14may be used expressly for this purpose while the proximal element lines90are removed. In any case, the repair of the leaflets or tissue may have been observed by non-invasive visualization techniques, such as echocardiography, to ensure the desired outcome. Then if the repair was not as desired, the fixation device14could be retrieved with the use of the tether or proximal element lines90so as to reconnect coupling member19with shaft12.

The proximal element lines90may be elongated flexible threads, wire, cable, sutures or lines extending through shaft12, looped through proximal elements16, and extending back through shaft12to its proximal end. When detachment is desired, one end of each line may be released at the proximal end of the shaft12and the other end pulled to draw the free end of the line distally through shaft12and through proximal element16thereby releasing the fixation device.

FIG.14illustrates a released fixation device14in a closed position. As shown, the coupling member19remains separated from the shaft12of the interventional tool10and the proximal elements16are deployed so that tissue (not shown) may reside between the proximal elements16and distal elements18.

Instead of using a push-to-open, pull-to-close mechanism for opening and closing distal elements18, a pull-to-open, push-to-close mechanism may also be used. For example, distal elements18may be coupled at their proximal ends to stud74rather than to coupling member19, and legs68may be coupled at their proximal ends to coupling member19rather than to stud74. In this example, when stud74is pushed distally relative to coupling member19, distal elements18would close, while pulling on stud74proximally toward coupling member19would open distal elements18.

B. Covering on Fixation Device

The fixation device14may optionally include a covering. The covering may assist in grasping the tissue and may later provide a surface for tissue ingrowth. Ingrowth of the surrounding tissues, such as the valve leaflets, provides stability to the device14as it is further anchored in place and may cover the device with native tissue, thus reducing the possibility of immunologic reactions. The covering may be comprised of any biocompatible material, such as polyethylene terephthalate, polyester, cotton, polyurethane, expanded polytetrafluoroethylene (ePTFE), silicone, or various polymers or fibers and have any suitable form, such as a fabric, mesh, textured weave, felt, looped or porous structure. Generally, the covering has a low profile so as not to interfere with delivery through an introducer sheath or with grasping and coapting of leaflets or tissue.

FIGS.15A-15Cillustrate a covering100on the fixation device14while the device14is in various positions. Additional description regarding such coverings may be found in PCT Publication No. WO 2004/103162, the disclosure of which is incorporated herein by reference in its entirety.

C. Locking Mechanism

As mentioned previously, the fixation device14optionally includes a locking mechanism for locking the device14in a particular position, such as an open, closed or inverted position or any position therebetween. It may be appreciated that the locking mechanism includes an unlocking mechanism which allows the device to be both locked and unlocked. Various locking mechanisms can be used with the fixation device14, such as those described in PCT Publication No. WO 2004/103162, which is incorporated herein by reference in its entirety.FIGS.16-19illustrate an exemplary locking mechanism106. Referring toFIG.16, the locking mechanism106is disposed between the coupling member19and the base69of the actuation mechanism58. The base69is fixedly attached to the stud74which extends through the locking mechanism106. The stud74is releasably attached to the actuator rod64which passes through the coupling member19and the shaft12of the interventional tool10. The base69is also connected to the legs68of the actuation mechanism58which are in turn connected to the distal elements18.

FIG.16also illustrates the proximal elements16, which straddle the locking mechanism and join beneath the locking mechanism106. The proximal elements16are shown supported by proximal element lines90. The proximal elements16are raised and lowered by manipulation of the proximal element lines90. In addition, lock lines92are shown connected with a release harness108of the locking mechanism106. The lock lines92are used to lock and unlock the locking mechanism106as will be described below. The proximal element lines90and lock lines92may be comprised of any suitable material, typically wire, nitinol wire, cable, suture or thread, to name a few. In addition, the proximal element lines90and/or lock lines92may include a coating, such as parylene. Parylene is a vapor deposited pinhole free protective film which is conformal and biocompatible. It is inert and protects against moisture, chemicals, and electrical charge.

FIG.17provides a front view of the locking mechanism106ofFIG.16. However, here the proximal elements16are supported by a single proximal element line90which is through both of the proximal elements16. In this arrangement both of the elements are raised and lowered simultaneously by action of a single proximal element line90. Whether the proximal elements16are manipulated individually by separate proximal element lines90or jointly by a single proximal element line90, the proximal element lines90may extend directly through openings in the proximal elements and/or through a layer or portion of a covering100on the proximal elements, or through a suture loop above or below a covering100.

FIGS.18-19illustrate the locking mechanism106showing the locking mechanism106in the unlocked and locked positions respectively. Referring toFIG.18, the locking mechanism106includes one or more wedging elements, such as rolling elements. In this example, the rolling elements comprise a pair of barbells110disposed on opposite sides of the stud74, each barbell having a pair of generally cylindrical caps and a shaft therebetween. The barbells110and the stud74are preferably comprised of cobalt chromium or stainless steel, however any suitable material may be used. The barbells110are manipulated by hooked ends112of the release harness108. When an upwards force is applied to the harness108by the lock line92(illustrated inFIG.16), the hooked ends112raise the barbells110against a spring114, as shown inFIG.18. This draws the barbells110up along a sidewall or sloping surface116which unwedges the barbells110from against the stud74. In this position, the stud74is free to move. Thus, when the lock line92raises or lifts the harness108, the locking mechanism106is in an unlocked position wherein the stud74is free to move the actuation mechanism58and therefore the distal elements18to any desired position. Release of the harness108by the lock line92transitions the locking mechanism106to a locked position, illustrated inFIG.19. By releasing the upwards force on the barbells110by the hooked ends112, the spring114forces the barbells110downwards and wedges the barbells110between the sloping surface116and the stud74. This restricts motion of the stud74, which in turn locks the actuation mechanism58and therefore distal elements18in place. In addition, the stud74may include one or more grooves82or indentations which receive the barbells110. This may provide more rapid and positive locking by causing the barbells110to settle in a definite position, increase the stability of the locking feature by further preventing movement of the barbells110, as well as providing a tangible indication to the user that the barbell has reached a locking position. In addition, the grooves82may be used to indicate the relative position of the distal elements18, particularly the distance between the distal elements18. For example, each groove82may be positioned to correspond with a 0.5 or 1.0 mm decrease in distance between the distal elements18. As the stud74is moved, the barbells110will contact the grooves82; by counting the number of grooves82that are felt as the stud74is moved, the user can determine the distance between the distal elements18and can provide the desired degree of coaptation based upon leaflet thickness, geometry, spacing, blood flow dynamics and other factors. Thus, the grooves82may provide tactile feedback to the user.

The locking mechanism106allows the fixation device14to remain in an unlocked position when attached to the interventional tool10during grasping and repositioning and then maintain a locked position when left behind as an implant. It may be appreciated, however, that the locking mechanism106may be repeatedly locked and unlocked throughout the placement of the fixation device14if desired. Once the final placement is determined, the lock line92and proximal element lines90are removed and the fixation device is left behind.

As described herein, at a later stage, e.g., during a new endovascular procedure, the fixation device may be disabled or removed by cutting or otherwise partitioning the fixation device, or cutting the fixation device from tissue surrounding the installed device. For example, at such a later stage (e.g., weeks, months, or years after initial placement), it may no longer be practical to remove the device by unlocking the locking mechanism and disengaging the device from the leaflets (e.g., due to tissue growth around, into, and over the device).

Advantageously, such disablement or removal of the fixation device may be achieved through an endovascular procedure, without requiring open heart access.

D. Overview of Delivery Device

FIG.20provides a perspective view of an embodiment of a delivery device or delivery catheter300which may be used to introduce and position a fixation device as described above. The delivery catheter300includes a shaft302, having a proximal end322and a distal end324, and a handle304attached to the proximal end322. A fixation device (not shown) is removably coupleable to the distal end324for delivery to a site within the body, typically for endovascular delivery to the mitral valve. Thus, extending from the distal end324is a coupling structure320for coupling with a fixation device. Also extending from the distal end324is an actuator rod64. The actuator rod64is connectable with the fixation device and acts to manipulate the fixation device, typically opening and closing the distal elements. Such coupling to a fixation device is illustrated inFIG.21.

The device may comprise a pair of distal elements and a pair of gripping elements as described herein. For example, each distal element and each gripping element may have a first end and a free end opposite the first end, the first ends of all of these elements being movably coupled together such that one distal element and one gripping element of the fixation device may be attached to the anterior leaflet, and one distal element and one gripping element of the fixation device may be attached to the posterior leaflet, and further comprising a locking mechanism which locks at least the distal elements in place, wherein the locking mechanism includes a release harness, wherein applying tension to the release harness unlocks the locking mechanism. In an embodiment, the release harness may from at or near the first ends of the distal and gripping elements at one end to past the free ends of the distal and gripping elements at an opposite end. Such a configuration advantageously makes it easier for a practitioner to access and engage a lock line92with the release harness. Such an embodiment is shown and described below in conjunction withFIG.38.

FIG.21illustrates an embodiment of a fixation device14coupled to the distal end324of the delivery catheter300. The shaft302is shown having a nose318near its distal end324. In this embodiment, the nose318has a flanged shape. Such a flanged shape prevents the nose318from being retracted into a guiding catheter or introducer as will be discussed in later sections. However, it may be appreciated that the nose318may have any shape including bullet, rounded, blunt or pointed, to name a few. Extending from the nose318is a compression coil326through which the coupling structure320and actuator rod64pass. The actuator rod64is coupleable, as shown, with the stud74of the fixation device14. Such coupling is illustrated inFIG.22.

FIG.22illustrates a portion of the shaft302of the delivery catheter300and a fixation device14which is coupleable with the catheter300. Passing through the shaft302is the actuator rod64. In this embodiment, the actuator rod64comprises a proximal extremity303and a distal extremity328, the distal extremity328of which is surrounded by a coil330. The proximal extremity303is typically comprised of a material such as stainless steel, nitinol, or Elgiloy®, to name a few, and may have a diameter in the range of 0.010 in. to 0.040 in., preferably 0.020 in. to 0.030 in., more preferably 0.025 in., and a length in the range of 48 to 72 in. The distal extremity328may be tapered, is typically comprised of stainless steel, nitinol, or Elgiloy®, to name a few, and may have a diameter in the range of 0.011 to 0.025 in and a length in the range of 4 to 12 in. Such narrowing increases flexibility of the distal end324of the actuator rod64. The actuator rod64further comprises a joiner332which is attached to the distal extremity328. The joiner332is removably attachable with stud74of the fixation device14. In this embodiment, the joiner332has internal threads which mate with external threads on the stud74of the fixation device14. As described previously, the stud74is connected with the distal elements18so that advancement and retraction of the stud74, by means of the actuator rod64, manipulates the distal elements. Likewise, the coupling member19of the fixation device14mates with the coupling structure320of the catheter300. Thus, the coupling member19and coupling structure320may function as previously described in relation toFIGS.6A-6B.

Referring back toFIG.21, the fixation device14may also include a locking mechanism which includes a release harness108, as previously described in relation toFIGS.16-19. Lock lines92are connected with the release harness108to lock and unlock the locking mechanism106as previously described. The lock lines92extend through the shaft302of the delivery catheter300and may connect with the release harness108in various arrangements as will be illustrated in later sections. Similarly, proximal element lines90extend through the shaft302of the delivery catheter300and connect with the proximal elements16. The proximal elements16are raised and lowered by manipulation of the proximal element lines90as previously described. The proximal element lines90may connect with the proximal elements16in various arrangements.

Referring back toFIG.20, the handle304attached to the proximal end322of the shaft302is used to manipulate the coupled fixation device14and to optionally decouple the fixation device14for permanent implantation. As described, the fixation device14is primarily manipulated by the actuator rod64, proximal element lines90and lock lines92. The actuator rod64manipulates the distal elements18, the proximal element lines90manipulate the proximal elements16and the lock lines92manipulate the locking mechanism. The actuator rod64may be translated (extended or retracted) to manipulate the distal elements18. This is achieved with the use of the actuator rod control314which will be described in later sections. The actuator rod64may also be rotated to engage or disengage the threaded joiner with the threaded stud74. This is achieved with the use of the actuator rod handle316which will also be described in later sections. Further, the proximal element lines90may be extended, retracted, loaded with various amounts of tension or removed with the use of the proximal element line handle312. The lock lines92may be extended, retracted, loaded with various amounts of tension or removed with the use of the lock line handle310. The actuator rod handle316, actuator rod control314, proximal element line handle312and lock line handle310are all joined with a main body308within which the actuator rod64, proximal element lines90and lock lines92are guided into the shaft302. The handle304further includes a support base306connected with the main body308. The main body308is slideable along the support base306to provide translation of the shaft302. Further, the main body308is rotatable around the support base306to rotate the shaft.

E. Delivery Catheter Shaft

FIG.23illustrates a cross-sectional view of the delivery catheter shaft302ofFIG.20. The shaft302has a tubular shape with inner lumen348and is comprised of a material which provides hoop strength while maintaining flexibility and kink resistance, such as a braided laminated material. Such material may include stainless steel braided or coiled wire embedded in a polymer such as polyurethane, polyester, Pebax, Grilamid TR55, and AESNO to name a few. To provide further support and hoop strength, a support coil346is disposed within the lumen348of shaft302as illustrated inFIG.23.

Additional description regarding such a catheter may be found in PCT Publication No. WO 2004/103162, the disclosure of which is incorporated herein by reference in its entirety.

In addition, at least one lock line shaft341having a tubular shape may be present having a lock line lumen340through which lock lines92pass between the lock line handle310and the locking mechanism106. The lock line shaft341extends through lumen348from the proximal end322to the distal end324of the shaft302. Therefore, the lock line shaft341typically has a length in the range of 48 to 60 in., an inner diameter in the range of 0.016 to 0.030 in., and an outer diameter in the range of 0.018 to 0.034 in. The lock line shaft341may be comprised of a 304V stainless steel coil, however, other structures or materials may be used which provide kink resistance and compression strength.

Similarly, at least one proximal element line shaft343having a tubular shape may be present having a proximal element line lumen342. Proximal element lines90pass through this lumen342between the proximal element line handle312and the proximal elements16. Thus, the proximal element line shaft343extends through lumen348from the proximal end322to the distal end324of the shaft302. Therefore, the proximal element line shaft343typically has a length in the range of 48 to 60 in., an inner diameter in the range of 0.016 to 0.030 in., and an outer diameter in the range of 0.018 to 0.034 in. The proximal element line shaft343may be comprised of a 304V stainless steel coil, however, other structures or materials may be used which provide kink resistance and compression strength.

It may be appreciated, however, that alternate shaft302designs may also be used. For instance, other shaft designs can be found in PCT Publication No. WO 2004/103162.

F. Lock Line Arrangements

As mentioned previously, when lock lines92are present, the lines92pass through at least one lock line lumen340between the lock line handle310and the locking mechanism106. The lock lines92engage the release harnesses108of the locking mechanism106to lock and unlock the locking mechanism106as previously described. The lock lines92may engage the release harnesses108in various arrangements, examples of which are illustrated inFIG.24. The two lock line lumens340are present within the shaft302of the delivery catheter300terminating at the nose318. The lumens340are disposed on alternate sides of the actuator rod64so that each lumen340is directed toward a release harness108.FIG.24illustrates an arrangement wherein two lock lines92,92′ pass through a single lock line lumen340and are threaded through a release harness108on one side of the actuator rod64(the actuator rod64is shown without surrounding housing such as coupling structure, for clarity). The lock lines92,92′ are then separated so that each lock line passes on an opposite side of the actuator rod64. The lock lines92,92′ then pass through the release harness108′ on the opposite side of the actuator rod64and continue together passing through a another single lock line lumen340′. This lock line arrangement is the same arrangement illustrated inFIG.21. Alternate lock line arrangements are possible, some of which can be found in PCT Publication No. WO 2004/103162, the disclosure of which is incorporated herein by reference in its entirety

It may be appreciated that a variety of lock line arrangements may be used and are not limited to the arrangements illustrated and described above. The various arrangements allow the harnesses108to be manipulated independently or jointly, allow various amounts of tension to be applied and vary the force required for removal of the lock lines when the fixation device is to be left behind. For example, a single lock line passing through one or two lumens may be connected to both release harnesses for simultaneous application of tension.

G. Proximal Element Line Arrangements

As mentioned previously, when proximal element lines90are present, the lines90pass through at least one proximal element line lumen342between the proximal element line handle312and at least one proximal element16. The proximal element lines90engage the proximal elements16to raise or lower the element16as previously described. The proximal element lines90may engage the proximal elements16in various arrangements, an example of which is illustrated inFIG.25. The two proximal element line lumens342are present within the shaft302of the delivery catheter300terminating at the nose318. The lumens342are disposed on alternate sides of the actuator rod64(the actuator rod64is shown without surrounding housing such as coupling structure, for clarity) so that each lumen342is directed toward a proximal element16.

FIG.25illustrates an arrangement wherein one proximal element line90passes through a single proximal element line lumen342. The proximal element line90is threaded through an eyelet360of a proximal element16on one side of the actuator rod64, passes over the actuator rod64and is threaded through an eyelet360′ of another proximal element16′ on the other side of the actuator rod64. The proximal element line90then passes through another single proximal element line lumen342′. This proximal element line arrangement is the same arrangement illustrated inFIG.21.

It may be appreciated that a variety of proximal element line arrangements may be used and are not limited to the arrangements illustrated and described above. For instance, and not by way of limitation, some alternate element line arrangements can be found in PCT Publication No. WO 2004/103162, the disclosure of which is incorporated herein by reference in its entirety. The various arrangements allow the proximal elements to be manipulated independently or jointly, allow various amounts of tension to be applied and vary the force required for removal of the proximal element lines when the fixation device is to be left behind. For example, a single proximal element line passing through one or two lumens in shaft302may be used for simultaneous actuation of both proximal elements.

H. Handle

FIG.26illustrates a handle304of the delivery catheter300. As mentioned previously, the actuator rod handle316, actuator rod control314, proximal element line handle312and lock line handle310are all joined with the main body318. The handle304further includes a support base306connected with the main body308. The main body308is slideable along the support base306to provide translation of the shaft302and the main body308is rotatable around the support base306to rotate the shaft.

It may be appreciated, that alternate handle304designs may also be used. For instance, further disclosure regarding handles can be found in PCT Publication No. WO 2004/103162, the disclosure of which is incorporated herein by reference in its entirety. For example, the handle may be designed to permit the manipulation of the lock lines and proximal element lines with the handle304or additional or different handles. Similarly, the handle may be designed to permit the manipulation of the actuator rod64.

I. Placement

To gain access to the mitral valve from the atrial side, an outer guide catheter may be tracked over a dilator and guidewire from a puncture in the femoral vein, through the inferior versa cava and into the right atrium. The outer guide catheter may be punctured through a fossa in the interatrial septum, into the left atrium. The outer guide catheter is then advanced through the fossa and curved by the primary curve so that the distal end is directed over the mitral valve. It may be appreciated that this approach serves merely as an example and other approaches may be used, such as through the jugular vein, femoral artery, port access or direct access, to name a few. For example, access to the heart may be accomplished through a thoracotomy or similar procedure involving, for example, trans-apical access to the left ventricle. Positioning of the distal end over the mitral valve may be accomplished by precurvature of the outer guide catheter, wherein the catheter assumes this position when the dilator and guidewire are retracted, and/or by steering of the outer guide catheter to the desired position. Any of the above described endovascular access procedures may similarly be used when disabling or removing a previously installed fixation device.

An inner guide catheter is advanced through the central lumen of the outer guide catheter and the distal end is positioned so that the central lumen is directed toward the target tissue, the mitral valve MV. In particular, the central lumen is to be directed toward a specific area of the mitral valve, such as toward the opening or openings between the valve leaflets or a device implanted in the mitral valve.

To gain access to the mitral valve from the ventricular side, an outer guide catheter may be tracked over a dilator and guidewire from a puncture in the femoral artery, through the aorta and into the left ventricle. The outer guide catheter is then advanced through the left ventricle so that the distal end is directed under the mitral valve. It may be appreciated that this approach serves merely as an example and other approaches may be used, such as through the jugular vein, femoral vein, port access or direct access, to name a few. For example, access to the heart may be accomplished through a thoracotomy or similar procedure involving, for example, trans-apical access to the left ventricle. Positioning of the distal end under the mitral valve may be accomplished by precurvature of the outer guide catheter, wherein the catheter assumes this position when the dilator and guidewire are retracted, and/or by steering of the outer guide catheter to the desired position. Any of the above described endovascular access procedures may similarly be used when disabling or removing a previously installed fixation device.

An inner guide catheter is advanced through the central lumen of the outer guide catheter and the distal end is positioned so that the central lumen is directed toward the target tissue, the mitral valve MV. In particular, the central lumen is to be directed toward a specific area of the mitral valve, such as toward the opening between the valve leaflets.

The specific features of the fixation device14described above and its method of implantation are merely illustrative. Other fixation devices may be employed, and any such devices may be removed using the methods and apparatuses disclosed below.

III. Methods of Disabling or Removing a Mitral Valve Fixation Device

Sometimes, after installation of a fixation device in the heart, it needs to be removed or disabled. Ordinarily, this has been done during an invasive procedure such as open heart surgery. Invasive procedures such as these often have high risk of complications, however. Further, sometimes mitral valve fixation devices are installed on patients for whom open heart or more invasive procedures are otherwise unnecessary or undesirable. For these patients, and even for patients in whom open-heart surgery is used, it would be beneficial to have devices and systems specifically designed for removing or disabling fixation devices within an endovascular procedure, rather than a procedure requiring open heart access.

Minimally invasive systems, methods, and devices for removing or disabling fixation devices are disclosed herein. These minimally invasive systems, methods, and devices allow a practitioner to remove the fixation device or disable it and, optionally, then proceed to do other things in the heart, without necessarily requiring open heart access or other more invasive procedures. Such systems, methods, and devices are configured to be effective even if the fixation device has been installed for weeks, months, or years, such that tissue surrounding the device may have grown over, into, or around the fixation device. As a result of such tissue growth, or for other reasons, unlocking and removal of the fixation device as described above that may be practical during the initial placement procedure may no longer be practical. The systems, methods, and devices disclosed herein may also be useful for adjusting the installation of a mitral valve fixation device after it is installed.

An embodiment of the present invention discloses systems that include various devices that may include catheters that perform various functions, and also multifunctional catheters that can perform any combination of functions. Such functions may include holding or retaining an installed fixation device; cutting or otherwise partitioning the fixation device, cutting a leaflet or leafets; removing a fixation device; and repairing the leaflet(s). Related methods for performing such functions are also disclosed.

The devices and associated methods and systems described herein may be used in combination with imaging modalities such as x-ray, fluoroscopy, echocardiography, charge coupled device cameras, complementary metal oxide semiconductor cameras, magnetic resonance imaging, and other imaging modalities. The availability of such imaging modalities during such procedures may help practitioners visualize, for example, where the fixation devices are, how they are connected to the heart, and where to direct the various catheters and/or other devices.

A. Systems for Removing or Disabling a Fixation Device

FIG.27illustrates an exemplary fixation device14that may be implanted in a mitral valve MV as described above, and that needs to be disabled or removed. According to an embodiment, two inner guide catheters, catheter400and catheter401may be disposed adjacent to the installed fixation device14in preparation for disabling or removing the fixation device14. Catheters400and401may advantageously be positioned in the heart following a similar endovascular deployment approach as described above. For instance, catheter400may be advanced into the left ventricle LV through an outer guide catheter405, and catheter401may be advanced into the left atrium LA through another outer guide catheter415. In some embodiments, both catheters400and401may be positioned in the heart on the same side of the mitral valve MV (either both in the left ventricle LV or both in the left atrium LA). In some embodiments, only one of catheters400or401may be used. In other embodiments, more than two catheters may be used. In some embodiments, one or more of the catheters400or401may initially be advanced into the left atrium LA, pass through one of the two orifices O (shown inFIG.35), and approach the fixation device14from the left ventricle LV. Similarly, one or more of the catheters400or401may initially be advanced into the LV, pass through one of the two orifices O (shown inFIG.35), and approach the fixation device14from the left atrium LA. It will be appreciated that any device or method described in relation to catheter400may also or instead be associated with catheter401. Similarly, any device or method described in relation to catheter401may also or instead be associated with catheter400.

In one embodiment, catheter400may be associated with a capture assembly402, while catheter401may be associated with a cutter assembly403. The capture assembly402may be mounted on or in catheter400, and may be advanced out of outer guide catheter405by e.g., advancing catheter400or retracting guide catheter405.

FIG.28illustrates an exemplary capture assembly402. Capture assembly may include an elongate member406which extends out the distal end of catheter400. In an embodiment, elongate member406may extend from the distal end404of the catheter400to a proximal handle manipulable by the practitioner. The elongate member406may be made of metal, plastic, or any suitable material, e.g., such as those described herein (e.g., cobalt-chromium alloys, stainless steel, nickel-titanium, Elgiloy®, etc. The elongate member406may be used to control a capturing mechanism407in the capture assembly402. As illustrated inFIG.28, the capturing mechanism407may comprise a lasso-type structure408. Other types of capturing mechanisms407may include, but are not limited to, for example, sheaths, conduits, expandable baskets, vacuums, magnets, vices, and clamps. Such capturing mechanisms, including lasso-type structure408are examples of retaining means, as they serve to retain the fixation device14within their control.

The lasso-type capturing mechanism408may include a portion of wire or cord409which is designed to assume an oval or ring-shaped structure410, at least when it is deployed outside the outer guide catheter405, and in which the size of the oval or ring-shaped structure can be adjusted. The portion of wire or cord409may be designed to be able to assume another shape when it is inside of the outer guide catheter405(e.g., it may comprise a superelastic nickel-titanium or other very flexible material). This may allow the lasso-type capturing mechanism408to be delivered in an outer guide catheter405with a smaller diameter than the diameter (or diameters) of the deployed ring or oval-shaped structure410.

The angle411between the plane on which the ring or oval-shaped structure410lies and the distal-most portion of the elongate member406, when the lasso-type capturing mechanism408is outside of the outer guide catheter405, may be varied depending on the direction from which the capture assembly402is intended to approach the fixation device14. For example, if the capture assembly402is intended to approach the fixation device14from directly below the fixation device14as it is installed in the heart, the angle411may be approximately 90°, as illustrated. In other embodiments, the angle may be about 45°, about 135°, or from about 45° to 135°. Other angles may also be provided, depending on the alignment characteristics of the procedure relative to the fixation device to be grasped therein. Preferably, the capture assembly402may be designed such that when the lasso-type capturing mechanism408is located in the outer guide catheter405, the angle411between the plane on which the ring or oval-shaped structure410lies and the catheters400and405may be or approximate 0° or 180°. This may also reduce the size of the outer guide catheter405needed to deliver the capture assembly402.

The lasso-type capturing mechanism408may be designed such that the portion of wire or cord409which is designed to assume an oval or ring-shaped structure410may be increased or decreased by controlling the elongate member406at the proximal end of the catheter. This allows for the diameter or circumference of the oval or ring-shaped structure410to be changed as appropriate once the lasso-type capturing mechanism408is advanced out of the outer guide catheter405in the heart. When the portion of wire or cord409is reduced, a part of the portion of wire or cord409may become part of the elongate member406. Similarly, when the portion of wire or cord409is increased, a part of the elongate member406may become part of the portion of wire or cord409.

The oval or ring-shaped structure410of wire409may be encircled by a helical loop412. Helical loop412may be formed of a wire having a smaller diameter than that of wire409. The helical loop412may wrap around the oval or ring-shaped structure410. This helical loop412may be made of metal, plastic, or other suitable material. Helical loop412may help the oval or ring-shaped structure410retain an approximately circular or oval shape and may also improve the ability of the lasso-type capturing mechanism408to grip the fixation device14and any tissue surrounding the fixation device14.

The helical loop412may be expandable or compressible so that the ability of the oval or ring-shaped structure410to be increased or decreased in circumference is not inhibited by the presence of helical loop412.

The oval or ring-shaped structure410is designed to be large enough or able to be enlarged such that it can encircle the fixation device14, or a portion thereof, and any tissue grown into or around that portion of the fixation device14to be captured. This may be achieved from the ventricle LV side of the mitral valve MV. When the oval or ring-shaped structure410is placed such that it encircles the fixation device14, or a portion of it, the elongate member406may be controlled in order to decrease the diameter of the oval or ring-shaped structure410. It may be beneficial for the diameter of the oval or ring-shaped structure410to be decreased once the oval or ring-shaped structure410is placed at a desired location around the fixation device14, in order to allow for the capture assembly402to provide a firm hold on the fixation device14.

In one embodiment, the capture assembly402includes a loop control element414that is located near the distal end of elongate member406, e.g., at or near the connection of the portion of wire or cord409and elongate member406. Loop control element414may include a tunnel formed therethrough, allowing the elongate member406to be passed through the loop control element414. The loop control element414may further be slidable along the elongate member406, such that sliding the loop control element414distally tightens or narrows the ring410, and sliding loop control element414proximally loosens or widens ring410. Manipulation of loop control element414may be achieved from the proximal end of the catheter400(e.g., through a push rod or similar mechanism), so as to change the length of the portion of wire or cord409, so as to loosen or tighten ring410. As such, loop control element414is an example of means for increasing or decreasing the size of the ring410.

As noted above, the catheter401may be associated with a cutter assembly403. After the fixation device14is stabilized and held by the capture assembly402, the cutter assembly403may be used to cut one or both leaflets LF in order to remove or disable the fixation device14. In some embodiments, the cutter assembly403may also be used to cut the fixation device14into two or more pieces, e.g., cutting device14into two pieces, and leaving one piece attached to each leaflet LF. While the device remains attached to the mitral valve (one portion attached to each leaflet), the fixation device may be thus disabled.

An exemplary cutter assembly403is illustrated inFIG.29. The cutter assembly403is associated with catheter401and is designed so that it can be delivered to near the mitral valve MV inside of an outer guide catheter415. In some embodiments, the cutter assembly403includes an elongate member416which may extend out the distal end of catheter401(e.g., it may extend the entire length of the catheter401to the proximal handle. The elongate member416may be made of metal, plastic, or any suitable material. The catheter401may be used to advance and retract the cutter assembly403within the outer guide catheter415and out the distal end417of the outer guide catheter415. The elongate member416may be used to control a cutting mechanism418in the cutter assembly403. As illustrated inFIG.29, the cutting mechanism418may include a blade420. Such a blade420is an example of means for cutting. Other exemplary cutting means may include, for example, radiofrequency energy emitters, lasers, other energy emitters (e.g., electrical current, etc.) that may serve to cut and/or cauterize tissue or the fixation device, and variously configured blades (e.g., an annular blade, rotating tip or blade, etc.). The cutter assembly403may be large enough that the entire fixation device may fit into the lumen434of the catheter401.

The blade420may be mounted in the cutter assembly403. The blade420is mounted so that the sharp edge421of the blade420faces the distal end417of the outer guide catheter415when the cutter assembly403is inside of the catheter415. Another cutting board of the cutter assembly403may be located distal to the blade420. The cutting board422may be approximately disk-shaped, and the cutting board422may be attached to the rest of the cutter assembly403by the elongate member416. Controlling the elongate member416from the proximal end of the catheter401may permit the cutting board422to be moved toward and away from the blade420. The blade420and cutting board422may function together to cut tissue that is brought between the blade420and cutting board422. As the cutting board422is drawn toward the blade420, the blade420will cut through tissue located between the sharp edge421of the blade420and the cutting board422, until the sharp edge421of the blade420comes into contact with the cutting board422. Depending on the size of the area to be cut, this cutting process may be repeated.

By controlling the catheter401from the proximal end of the catheter401, the cutter mechanism418may be advanced into the left atrium LA until the cutting board422and blade420are located adjacent to tissue to be cut. This may entail lowering the cutter mechanism418partially into one of the orifices of the double orifice structure formed by the implantation of the fixation device14.

The cutter assembly430may approach the fixation device14from the left atrium LA, or from the left ventricle LV.

In order to disable the fixation device14, one mitral valve leaflet LF could be cut adjacent to the free end54of one of the distal elements18of the fixation device14in order to separate that mitral valve leaflet LF from that distal element18and its associated proximal element16. (For the structure of the fixation device14, see, e.g.,FIG.7.) The fixation device14may also be separated from both leaflets LF for removal by cutting both leaflets LF adjacent to each free end54of the distal elements14.

The sharp edge421of the blade420may or may not be parallel to the distal edge423of the catheter401. The sharp edge421of the blade420may be linear, or it may be annular, following all or a portion of the arc associated with the inside circumference of catheter401, or another appropriate shape.

The cutting board422may be made of a material which allows for the blade420to, after cutting through tissue, slightly cut into the cutting board422. However, the cutting board422should be made of a hard enough material that the blade420does not slice all of the way through the cutting board422. It may be preferable to have the cutting board422comprise two different materials. At the most distal end424of the cutting board, a harder material may be used, and on the surface425which the blade420cuts against, a softer material may be used. If the sharp edge421of the blade420is not parallel to the distal edge423of the catheter, it may be desirable to have the surface425designed so that the connection between the blade420and the surface425is substantially continuous when the cutting board422is drawn up against the blade420.

The cutter assembly403may comprise a sharp blade421located at the distal end423of a catheter401, and further comprise a cutting board422disposed distal to the sharp blade421, said assembly403being designed so that leaflet tissue LF may be maneuvered into a space between the blade421and the cutting board422, and by moving the cutting board422or the blade421, the tissue LF may be cut by the blade421.

In another embodiment, the catheter401ofFIG.27may comprise a cutter assembly430configured for both separating the fixation device14from the leaflets LF and removing the fixation device14from the heart. The catheter400may be associated with a stapler assembly431for affixing the leaflets LF before, after, or while the fixation device14is separated from them. For example, the leaflets may be stapled or otherwise joined together prior to removal of the fixation device14, particularly where portions of leaflets LF are removed with device14.

As shown inFIG.30A, the catheter401may comprise a cutter assembly430having a distal end423which comprises an annular blade432. After being advanced out of the outer guide catheter405, the catheter401is pushed around the fixation device14from below. The annular blade432will cut the tissue LF to which the fixation device14is attached in order to at least partially separate the fixation device14from the tissue it is connected to. The annular blade432may function similar to an apple corer, as it punches into the tissue LF surrounding the fixation device14.

The cutter assembly430may further comprise a grabbing mechanism433located within the lumen434of the catheter401. The grabbing mechanism433is slidably movable within the lumen434, and can be slidably moved toward and away from the distal end423of the catheter401.

The grabbing mechanism433may comprise a stationary arm435and a moveable arm436. The grabbing mechanism433may further comprise an elongate member437that runs the length of the catheter401and connects to the moveable arm436. The elongate member437may be used to manipulate the moveable arm436from the proximal end of the catheter401. By moving the moveable arm436closer to the stationary arm435, grabbing mechanism433may be placed in a closed position, and by moving the moveable arm436away from the stationary arm435, the grabbing mechanism433may be placed in an open position. The elongate member437may also permit the slidable movement of the grabbing mechanism433. In other embodiments, both arms435and436may be moveable. The grabbing mechanism433may function similar to tweezers. By applying force to one or both sides of the fixation device14, the grabbing mechanism433may stabilize the fixation device14, serve as a retaining means for retaining the device14in the control of the person manipulating the catheter401, and assist with the removal of the device14from the patient.

The grabbing mechanism433may be used to help hold the fixation device14and any immediately surrounding tissue in the catheter401. Once the fixation device14is separated from the heart, it may then be removed from the heart.

The grabbing mechanism used in the cutter assembly430may instead comprise a lasso-type capturing mechanism408, as described above in reference toFIG.28, or any other type of capturing mechanism. It may be preferable, if a lasso-type capturing mechanism408is used with the cutter assembly430, for the cutter assembly430to approach the fixation device14from the ventricle side of the heart.

The lasso-type capturing mechanism408could be advanced from within the catheter401, and used to firmly hold onto the fixation device14. Then the catheter401could be advanced toward the fixation device14so that the annular blade432cuts the fixation device14out of the leaflet tissue. The cutter assembly430could then be withdrawn from the heart with the fixation device14. As described herein, the leaflets may be stapled or otherwise joined together at a location adjacent to fixation device14prior to removal of device14, particularly where some leaflet tissue surrounding device14is removed with device14. This prevents formation of an unwanted hole or holes within the mitral valve where device14once resided, as a result of removal of device14with a small amount of surrounding leaflet tissue. This may be helpful, so as to prevent such a hole from preventing desired closing of the mitral valve during its normal operation.

In another embodiment, the cutter assembly430may use as its cutting means radiofrequency energy, laser energy, a rotating tip or other cutter as its cutting mechanism, instead of or in addition to the annular blade shown inFIG.30A. Additional or alternative grabbing mechanisms433may also be used as retaining means. For example, the grabbing mechanism may be replaced by a vacuum mechanism or a lasso-type capturing mechanism.

The cutter assembly430may approach the fixation device14from the left atrium LA, or may approach the fixation device14from the left ventricle LV. In some embodiments, as depicted schematically inFIGS.30B-30C, the cutter assembly430may be configured and/or maneuvered so that the annular blade432is advanced between the distal elements18and proximal elements16of the fixation device14. This may serve to separate the proximal elements16from the leaflet tissue LF.

FIGS.30B-30Cshow progressive cross sectional views of the cutter assembly430cutting the leaflet tissue LF in this way. Because the proximal elements16may be designed to help grip the leaflet tissue LF, cutting between the distal elements18and proximal elements16of the fixation device14may reduce damage to other portions of the leaflet tissue LF by allowing the fixation device14to be pulled away from the mitral valve MV without needing to cut the entire fixation device14out of the mitral valve MV.

Before, while, or after the cutter assembly430cuts or separates the leaflets LF from the fixation device14, a grabbing mechanism433or a capturing mechanism407associated with a separate catheter441may be placed in close proximity to the fixation device on either the atrial side AS or ventricle side VS of the mitral valve MV. The grabbing mechanism433or capturing mechanism407may be associated with a separate catheter441.

As illustrated inFIG.30B, one method for placing the grabbing mechanism433or capturing mechanism407in close proximity to the fixation device on the ventricle side VS may involve placing the catheter441and the grabbing mechanism433or the capturing mechanism407(or just the grabbing mechanism433or the capturing mechanism407) from the atrial side AS of the mitral valve MV and through an orifice of the mitral valve MV to reach the fixation device14from the ventricle side VS. Preferably, this is done prior to removal of the clip, while there are two orifices of the mitral valve MV.

As shown inFIG.30B, the capturing mechanism407comprises a type of snare or lasso structure442that may comprise a loop446, a connection or cinch point448, and an arm450.

Once the proximal elements16are separated from the leaflets LF, the grabbing mechanism433or capturing mechanism407associated with a separate catheter441may be used to pull the fixation device14apart from the mitral valve MV. Or, after the fixation device14is cut apart from or otherwise separated from the leaflets LF, the grabbing mechanism433or a capturing mechanism407associated with a separate catheter441may be used to pull the fixation device14apart from the mitral valve MV.

FIGS.30D-30Eshow progressive cross sectional views of the cutter assembly430removing the fixation device14from the leaflet tissue LF shortly after implantation of device14and before extensive tissue in-growth has occurred. Before extensive tissue in-growth has occurred, it may be possible to separate the proximal elements16from the leaflet tissue LF without needing to cut the leaflet tissue LF. This method may reduce damage to the leaflet tissue LF by allowing the fixation device14to be pulled away from the mitral valve MV without needing to cut leaflet tissue LF surrounding the fixation device14. For example, cutter assembly may be advanced between the leaflet tissue LF and proximal elements16, and manipulated to work leaflet tissue LF away from proximal elements16. Once the proximal elements16are separated from the leaflets LF, the grabbing mechanism433or a capturing mechanism407associated with a separate catheter may be used to carefully pull the fixation device14apart from the leaflets LF of mitral valve MV. Other devices than the cutter assembly430may also be used to separate the proximal elements16from the leaflet tissue LF in this method.

FIG.30Eadditionally shows an unlocking device452which may be used to unlock the release harness108of the fixation device14. The unlocking device452may be advanced into the left ventricle LV from the atrial side AS of the heart, through an orifice O. The unlocking device452may be associated with catheter400. The unlocking device452may comprise an elongate body454and a hook456with a tip458. The tip458of the hook456may be manipulated to unlock the release harness108. The release harness108is preferably radiopaque and the hook456is also preferably radiopaque, so that they may be viewed via x-ray or other imaging technique. It may also be possible to view the release harness108and hook456through an echocardiogram.

The cutter assembly430may further comprise a catheter400including a stapler assembly431for affixing the leaflets LF. As depicted inFIG.31, the stapler assembly431is located at the distal end404of the catheter400.

The stapler assembly431may provide a means for installing a staple461into each leaflet LF before, after, or while the fixation device14is removed. One staple461may be used for the anterior mitral valve MV leaflet LF, and another staple461for the posterior mitral valve MV leaflet LF, if both leaflets LF are cut. Each staple461upon deployment may serve to pull together the part of a leaflet LF where the fixation device14was cut out or is going to be cut out. In another embodiment, a staple may hold both leaflets LF together, if desired.

The leaflets may be stapled or otherwise joined together prior to or simultaneous with removal of the fixation device14, particularly where portions of leaflets LF are removed with device14. For example, the leaflets may be stapled or otherwise joined together at a location adjacent to fixation device14prior to removal of device14, particularly where some leaflet tissue surrounding device14is removed with device14. This prevents formation of an unwanted hole within the mitral valve where device14once resided, as a result of removal of device14with a small amount of surrounding leaflet tissue. This may be helpful, so as to prevent such a hole from preventing desired closing of the mitral valve during its normal operation. Any joining mechanism may be employed (e.g., staple, of fastener, sutures, etc.). For example,FIG.35illustrates a suture purse-string type joining of the opposed leaflets LF. Such a purse-string technique and mechanism could be used prior to or simultaneous with removal of device14, so as to prevent a hole from being present where leaflet tissue is removed with device14.

The catheter400holds a staple461in a position in which it can be installed into a mitral valve MV leaflet LF. By controlling the proximal end of the catheter400, the staple461is directed to a leaflet LF and pushed into the leaflet. The catheter400releases the staple461after it is installed in a leaflet LF.

Each staple461may be made of a shape-memory alloy such as Nitinol.FIGS.32A-32Bschematically illustrate the use of such a staple461. The staple461may be V-shaped when initially inserted into mitral valve MV tissue LF. Then as the staple461comes to body temperature, it may then become U-shaped (461a), e.g., a closed U-shape, pulling together the mitral valve MV tissue LF. In another embodiment, the staple461may be a shape-memory material that assumes a J-shape as it comes to body temperature. The staple461amay pull the tissue together, or the tissue may first be pulled together by another device and then stapled. It will be appreciated that staples with different configurations may also support repair of the tissue. Each staple461may also be biodegradable or bioabsorbable, or made of any suitable material, such as a polymer. The staple or staples461may also serve to join the two leaflets LF together. This may approximate the position the leaflets LF were in when the fixation device14was installed.

The staple or staples461may be installed into the leaflet or leaflets LF in an un-deployed state prior to the removal of the fixation device14and then assume or be made to assume a deployed state after the fixation device14is removed.

As shown inFIGS.32A and32B, it may be preferable to have a barb or barbs463at the ends or along the edges or sides of the staples which are inserted into tissue. This may permit the staples461to affix more stably or irreversibly to the leaflet tissue LF. Instead of passing all of the way through the leaflet tissue LF, as depicted inFIG.32B, a staple461may be placed only partially through the tissue. In another embodiment, it may be preferable to have the staple461designed so that they can be removed from the leaflet tissue LF easily during installation and re-positioned as necessary.

The staple means at a distal end of catheter400may comprise a staple461detachably retained on a distal end404of a catheter400, wherein said staple461is configured to pull or hold damaged tissue together in a position that approximates a healed tissue configuration.

In one embodiment, the staple461may be installed by a device such as or similar to a surgical tissue stapler. In another embodiment, the staple461may be installed using an anvil held by a separate catheter. The staple461may be pressed against the anvil to assume the desired closed staple configuration. Straight, curved, or circular staples may be used, for example. The stapler may comprise a knife to both assist with removal of the fixation device14and affix the tissue LF after cutting. Such staples491may be made of any suitable substance, such as titanium or nitinol, and may even be bioabsorbable. In addition to staples461, clips may also be used.

In other embodiments, other methods or means for repairing the leaflets LF may include, but are not limited to, thermal energy, purse string suturing, purse string suturing anchored with barbs, staples, sutures or wire, cinching of barbs, sutures, or wires, etc. Either or both of catheters400and401may be associated with devices capable of performing any of these methods.

In another embodiment, the catheter400ofFIG.27may be associated with a cone assembly470and the catheter401may be associated with a suture assembly480, as shown inFIGS.33-34.

The cone assembly470may comprise a balloon472in the shape of a hollow cone that is located on the distal end404of the catheter400.

More particularly, the balloon472may be shaped like a hollow cone with its apex cut off (that is, a hollow truncated cone or frustum). For example, as shown inFIG.33, the balloon472is oriented such that the apex of the cone (if it had an apex) would face toward the proximal end of the catheter400.FIG.33shows the balloon inflated. Such a cone structure may be particularly well-suited to the functions of the present methods, although other structures may also be used.

Preferably the balloon472is advanced into the left ventricle LV of the heart in a deflated condition. Once it is positioned, for example, beneath the fixation device14in the left ventricle LV, the balloon472is inflated. Techniques for the inflation of balloons located on catheters are known in the art. For example, the balloon472may be inflated with inflation material such as water, saline, or a gas. In one embodiment, the balloon472is configured so that the entire fixation device14, as well as any tissue growing around the distal elements of the fixation device14, can fit within the cavity477created by the balloon472.

As illustrated inFIG.33, heating elements473may be located on the interior surface474of the balloon472. The heating elements473may be intermittently spaced or form a continuous strip of heating elements473within the interior periphery of the balloon472, or be placed in a variety of patterns or arrangements on the interior surface474of the balloon472. The heating elements473may be configured so that heat can be selectively applied to the tissue around the fixation device14. The balloon472may also be lined with radiofrequency elements or similar energy delivery elements. In another embodiment, the hollow conical structure may be a solid structure rather than a balloon.

Preferably, the device is designed so that the heating elements473can be selectively turned on, off, and otherwise controlled from the handle at the proximal end of the catheter400. The heat energy may be used to separate the leaflet tissue LF from the fixation device14. The heat energy may be applied to a portion of leaflet tissue LF distal to the free ends54of the distal elements18of the fixation device14(e.g., just beyond the edge of distal elements18).

The cone assembly470may be configured to deliver other forms of energy in addition to or instead of heat energy, such as radiofrequency energy, laser, etc., for the purpose of separating the leaflet tissue LF from the fixation device14. The heat or other energy may also be used to fuse or partially fuse the leaflet tissue LF together to repair it. If thermal energy is used to repair the leaflets LF, a vice or jaw may be used to secure the damaged portions of a leaflet to each other prior to thermal fusing. The heat or other energy could also be used to fuse the two leaflets to each other. For example, it may be desirable to fuse the two leaflets together in a position approximating their configuration when fixation device14was installed (e.g., similar to purse-string suturing of leaflets LF inFIG.35). It may be possible for heat or other energy to be applied to the tissue and have that energy serve to cut the leaflet tissue LF in such a way that the fixation device14can be removed from the tissue LF. Such energy employed for cutting may at the same time cauterized and seal the tissue. The cone assembly470is another example of cutting means.

If the cone assembly470is used to separate both leaflets LF from the fixation device14—as opposed to separating one leaflet LF, and thereby disabling the fixation device14—the fixation device14may then be removed from the heart. The balloon472may be deflated around the fixation device14prior to removal of the cone assembly470and the fixation device14. As such, the cone assembly may also be an example of retaining means. Alternatively, a sheath (not pictured) may be advanced over the balloon472to capture the fixation device14. The fixation device14may also be captured into a conduit or expandable basket (not pictured).

The cone assembly470may further include a vacuum mechanism475. The vacuum mechanism475may comprise a tube or lumen476within the catheter400as depicted inFIG.33. A suction or other vacuum device (not pictured) may be connected at the proximal end of the catheter (not pictured), for example, at the handle304, to apply a suction force at the proximal end of the tube or lumen476of the vacuum mechanism475. This suction force may be translated along the length of the tube or lumen476to help hold the separated fixation device14in the balloon472. This may be useful, for example, to permit the fixation device14to be withdrawn out of a side access point in the heart, as it may help prevent the fixation device14from falling out of the balloon472. In uses where the fixation device14is made from a magnetic material, a magnet in the cone assembly430may also perform this function. The cone assembly470may also include any of the other retaining means described herein, and the cone assembly470may be itself considered a retaining means.

The cone assembly470may comprise a device configured to remove a fixation device14by the selective application of thermal, electrical, or other types of energy to leaflet tissue LF located near the fixation device14. It may further comprise a retaining means for ensuring that the fixation device14is retained within the cone assembly470for removal from the heart, such as a vacuum mechanism475.

The system may further comprise a catheter401associated with a suture assembly480for affixing the leaflets LF. As depicted inFIG.34, the suture assembly480may be disposed at the distal end423of the catheter401.

Suture assembly480may comprise a needle482and a thread, cord, or wire483. The suture assembly480may also comprise sutures with barbs. Such a suture assembly480may serve to close or otherwise repair a cut on leaflet(s) LF after fixation device14has been removed. As described above, such suturing or other joining of leaflets LF may be performed prior to or simultaneous with removal of device14.

Even after the fixation device14is removed, it may be desired to maintain the mitral valve MV structure in a double-orifice configuration (e.g., similar to that shown inFIG.4). Therefore, the present methods may include suturing (e.g., using suture assembly480) to suture leaflets LF. In an embodiment, leaflets may be purse-string sutured, as pictured inFIG.35. In such a method, the A2 region of the mitral valve MV is sutured to the P2 region. Before, after, or while the fixation device14is cut out of the mitral valve MV, a suture assembly (e.g., assembly480) may be used to suture the two leaflets LF to each other. This suturing may maintain the leaflets in (or return the leaflets to) approximately the same arrangement they were in prior to the fixation device14being removed. The suture thread, cord, or wire483could be sewn into one leaflet LF and then the other, and then pulled taut like a purse string. A suture assembly may also be used to suture each leaflet LF separately, to assist the leaflets LF in healing or prepare them for further procedures to be performed. It may be preferable to place the sutures prior to removal of the fixation device14, and draw them taut after the fixation device14is removed.

Anchoring for the purse string sutures may be achieved by using a suture anchor, barbs, staples, additional sutures, wire, etc. Alternatively, the leaflet(s) LF may be repaired by using cinching of barbs, sutures, anchors with eyelets, or wires. For example, hooked barbs may be installed on one leaflet LF, while a corresponding barb with an eye may be installed on the other leaflet. The hook of the hooked barb on one leaflet may be engaged with the eye of the barb on the other leaflet to hold both leaflets LF of the mitral valve MV together. It may be preferable to affix the sutures, barbs, staples, wires, etc. or other mechanism for attaching opposed leaflets LF prior to removal of the fixation device14. For example, it may be easier to secure the leaflets to one another prior to removal of device14, as device14serves to anchor and hold leaflets adjacent one another. In addition, particularly where any leaflet tissue LF is removed with device14, it may be preferred to secure the leaflets to one another at a location adjacent to device14(e.g., by staple, suture, etc.) so as to prevent formation of a hole that would resist closure during the systolic portion of the cardiac cycle where device14and removed leaflet tissue LF once was. In one embodiment, it may be desired to place needles or hooks into the tissue LF before the leaflet device before the fixation device14is removed, and then draw the needles or hooks through the tissue to bring the leaflets LF together or repair each leaflet LF separately.

In another embodiment, the catheter400ofFIG.27may be associated with a cutter assembly490. As illustrated inFIG.36, the cutter assembly490may be located at the distal end404of the catheter400. The cutter assembly490may comprise a pair of arms491and492. At least one of the arms490and491may be capable of being moved in a scissor-like fashion and capable of being controlled from the proximal end of the catheter400(e.g., at a handle). The moveable arms491and492may be controlled to close around a fixation device14and cut the fixation device14into approximately two pieces. One portion of the fixation device14(e.g., including a set of one proximal element16and one distal element18) may remain with one leaflet LF of the mitral valve MV while the remaining portion of the fixation device14(e.g., including a set of one proximal element16and one distal element18) may remain with the other leaflet LF of the mitral valve MV. The cutter assembly490may use mechanical force, heat, radiofrequency energy, or any other suitable cutting mechanism to partition the fixation device into two or more portions, separating the leaflets of the mitral valve. Catheter400may further include an enclosure (not pictured) or other stabilizing mechanism to hold the parts of the fixation device14while the device is being cut.

The moveable arms491and492may also be closed around a leaflet LF adjacent to the free end54of one of the distal elements18of the fixation device14in order to separate that mitral valve leaflet LF from its corresponding distal element18. Such a method may leave the device14attached to only one of the leaflets. The cutter assembly490may also be used to separate both leaflets LF from the fixation device14, after which the device may be removed from the body.

As with the other procedures described herein, this may be done in preparation for further procedures being performed on the mitral valve MV, such as mitral valve annuloplasty, balloon valvuloplasty, mitral valve repair, or installation of a replacement valve.

The cutter assembly490may further comprise thermal, electric, or other elements used to cauterize the leaflet tissue LF (e.g., to cut and cauterize substantially simultaneously). The cutter assembly490may be configured that, at the same time heat or other energy is used to separate a leaflet LF from the fixation device14, the heat cauterizes or fuses the tissue to repair it.

The cutting mechanism associated with the cutter assembly490may be particularly configured for cutting leaflet tissue LF or the fixation device14. For example, the Abbott Vascular MitraClip® fixation device is formed of a cobalt-chromium alloy, is covered with polyester, and may include a nitinol component, so a cutting tool sufficient to cut through one or more of those materials may be provided to remove a MitraClip® fixation device. Where the cutter assembly490is merely used for cutting leaflet tissue, the materials and/or specifications of the cutter assembly490may be different.

After a fixation device14is installed in the heart, tissue typically grows around the device. Cutting the fixation device14into two parts may be done even when the fixation device14is fully in-grown, or if the device is only partially in-grown, or not in-grown to any significant degree. If the fixation device14is to be left in the heart after it is cut (e.g., partitioning it into two portions, one remaining with each leaflet), it may be preferable to ensure that the fixation device14is fully or substantially fully in-grown prior to cutting.

B. Improved Fixation Device with a More Easily Accessible Harness

As shown and described in conjunction withFIGS.16-19, the implanted fixation device14may have a release harness108which can be used to release the locking mechanism106. When the locking mechanism106is released, the fixation device14may be more easily removed. The present systems may include a catheter-based device used to activate (e.g., unlock) the release harness108, such as a catheter with a hook, lock lines, or other engagement structure on its distal end that can engage release harness108, such as hook456.

In many circumstances, tissue may have grown around the fixation device14, and the release harness108may no longer be readily accessible to interventional tools. As such, according to one embodiment, an improved fixation device14is provided. Such an improved device14may include features making it easier to access release harness108and release the locking mechanism106on of the fixation device14in the process of removing it after it has been installed in a heart.

For example, the fixation device14release harness108may be extended in length to increase the accessibility of the release harness. If the release harness108were longer, for example, as the release harness108″ shown in device14ofFIG.37, then a hook or other engagement device on a catheter, such as hook456, advanced into the heart from the atrial or ventricular side may be able to more easily unlock the fixation device14using the release harness108″ even after tissue has grown up around much or substantially all of the fixation device14. For example, as illustrated inFIG.37, the release harness108″ may extend beyond the free ends of the proximal elements16, distal elements18, or both when the device is in a closed and locked position, as shown.

Unlocking the fixation device14may allow for the proximal elements16and distal elements18to be more easily removed from the leaflets LF and for the device14to be more easily removed from the heart. With the fixation device14unlocked, a catheter with a retaining means and/or a catheter with a cutting means may be used to pull or push the distal elements18away from the leaflets LF. It may be necessary to stabilize the fixation device from the opposite (e.g., ventricle) side prior to accessing the release harness108. It may only be possible to remove the fixation device14by unlocking the harness108prior to extensive tissue in-growth occurring around the device. For example, this method may be particularly helpful within about 7 days, 15 days, 30 days, or 60 days after implantation of the fixation device. As the rate of tissue growth may vary in individuals based on a variety of factors, and tissue is radiolucent, it may not be possible to know whether tissue growth is too extensive for the release harness108to be unlocked without attempting to unlock it.

In another embodiment, an improvement to the fixation device14may be to make it biodegradable while still serving to secure the leaflets together, so that if, for example, a replacement valve is later installed, the fixation device14may have biodegraded and only the leaflets LF will need to be separated (e.g., grown together as the device14biodegrades).

In another embodiment, it may be preferable to implant a replacement valve in each of the orifices using the fixation device as an anchor. A device comprising two replacement valves and shaped approximately like a figure-eight may be so installed. This may be desirable if mitral regurgitation reduction is insufficient and the fixation device14cannot be removed or its removal would otherwise be undesirable. Such replacement valve devices, systems, and methods are disclosed in U.S. application Ser. No. 14/216,813, herein incorporated by reference in its entirety.

C. Double Orifice Balloon Valvuloplasty

In some circumstances, such as when mitral valve stenosis occurs after the implantation of a fixation device14, and the fixation device is not able to be removed, or removal is otherwise undesirable, balloon valvuloplasty may be performed in both orifices. This valvuloplasty may be performed in both orifices simultaneously or in one orifice first and then in the other orifice. It may be possible to anchor a device for performing the balloon valvuloplasty to the fixation device14. Performing balloon valvuloplasty in both orifices simultaneously or nearly simultaneously may support the procedure.

For example, as illustrated inFIG.38, a catheter401may be associated with a double balloon valvuloplasty assembly500. The balloon valvuloplasty assembly500may comprise two arms501and502which are configured so that, once the balloon valvuloplasty assembly500is advanced out of the outer guide catheter415, the two arms501and502separate at an appropriate distance so that one arm501can be advanced into one orifice of the mitral valve double orifice structure formed by a fixation device14and the other arm502can be advanced into the other orifice (e.g.,FIGS.4and35show the two orifices O). Arms501and502each have a balloon503and504disposed at or near a distal end of each respective arm. Balloons503and504can be inflated when the arms501and502are advanced to a position within the orifices O. The inflation of the balloons503and504may be done by methods known in the art, and can be controlled by a handle located at the proximal end of the outer guide catheter415.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.