Patent Description:
The mitral valve controls blood flow from the left atrium to the left ventricle of the heart, preventing blood from flowing backwards from the left ventricle into the left atrium so that it is instead forced through the aortic valve for delivery of oxygenated blood throughout the body. A properly functioning mitral valve opens and closes to enable blood flow in one direction. However, in some circumstances the mitral valve is unable to close properly, allowing blood to regurgitate back into the atrium.

Mitral valve regurgitation has several causes. Functional mitral valve regurgitation is characterized by structurally normal mitral valve leaflets that are nevertheless unable to properly coapt with one another to close properly due to other structural deformations of surrounding heart structures. Other causes of mitral valve regurgitation are related to defects of the mitral valve leaflets, mitral valve annulus, or other mitral valve tissues.

The most common treatments for mitral valve regurgitation rely on valve replacement or repair including leaflet and annulus remodeling, the latter generally referred to as valve annuloplasty. One technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the "bowtie" or "edge-to-edge" technique. While all these techniques can be effective, they usually rely on open heart surgery where the patient's chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated high mortality and morbidity. In some patients, a fixation device can be installed into the heart using minimally invasive techniques. The fixation device can hold the adjacent segments of the opposed valve leaflets together and may reduce mitral valve regurgitation. One such device used to clip the anterior and posterior leaflets of the mitral valve together is the MitraClip® fixation device, sold by Abbott Vascular, Santa Clara, California, USA.

However, sometimes after a fixation device is installed, undesirable mitral valve regurgitation can still exist, or can arise again. For these sub-optimally treated patients, the presence of a fixation device in their mitral valves may obstruct additional procedures such as transcatheter mitral valve replacement. These patients may also be considered too frail to tolerate open-heart surgery, so they are often left with no viable options to further improve the function of their mitral valve.

In <CIT>, there is described an interventional device for cutting tissue at a targeted cardiac valve, such as a mitral valve. The interventional device includes a catheter having a proximal end and a distal end. A cutting mechanism is positionable at the distal end, such as by routing the cutting mechanism through the catheter to position it at the distal end. The cutting mechanism includes one or more cutting elements configured for cutting valve tissue when engaged against the tissue. A handle is coupled to the proximal end of the catheter and includes one or more controls for actuating the cutting mechanism.

In <CIT>, there is described a system for accessing a patient's cardiac anatomy which includes an endovascular aortic partitioning device that separates the coronary arteries and the heart from the rest of the patient's arterial system. The endovascular device for partitioning a patient's ascending aorta comprises a flexible shaft having a distal end, a proximal end, and a first inner lumen therebetween with an opening at the distal end. The shaft may have a preshaped distal portion with a curvature generally corresponding to the curvature of the patient's aortic arch. An expandable means, e.g. a balloon, is disposed near the distal end of the shaft proximal to the opening in the first inner lumen for occluding the ascending aorta so as to block substantially all blood flow therethrough for a plurality of cardiac cycles, while the patient is supported by cardiopulmonary bypass. The endovascular aortic partitioning device may be coupled to an arterial bypass cannula for delivering oxygenated blood to the patient's arterial system. The heart muscle or myocardium is paralyzed by the retrograde delivery of a cardioplegic fluid to the myocardium through patient's coronary sinus and coronary veins, or by antegrade delivery of cardioplegic fluid through a lumen in the endovascular aortic partitioning device to infuse cardioplegic fluid into the coronary arteries. The pulmonary trunk may be vented by withdrawing liquid from the trunk through an inner lumen of an elongated catheter. The cardiac accessing system is particularly suitable for removing the aortic valve and replacing the removed valve with a prosthetic valve.

In <CIT>, there are described prosthetic valves implantation methods and systems, especially as related to preparing the native site of a native stenotic or incompetent aortic valve for receipt of a prosthetic replacement valve are described. The subject tools and associated site preparation techniques may be employed in percutaneous aortic valve replacement procedures.

In <CIT>, there is described a medical device for safely and effectively removing a clip or a suture from a heart valve is operable in association with a guidewire for positioning the device in proximity to the heart valve. The apparatus may include a blade for cutting a tissue bridge including the clip and an arrangement for removing the tissue bridge from the heart valve. The apparatus may include two arms that secure the clip. The blade may be deployed to core out a central portion of a tissue bridge, including the clip or the suture, from the heart valve. The blade may be activated by an actuator. A retrieval member may be configured to capture the tissue bridge and the clip or suture after excision by the blade.

In <CIT>, there is described a system for excising an implanted clip approximating opposed valve leaflets in a heart valve includes a capture catheter configured to be introduced proximate the valve leaflets on one side of the clip, a transfer catheter configured to be introduced proximate the valve leaflets on another side of the clip, and a cutting tool configured to be deployed between the capture and transfer catheters and to be engaged against tissue of at least one of the valve leaflets and to excise the clip. A removal catheter may optionally be used to remove the clip from the heart.

In <CIT>, it is described that suturing apparatuses can be configured to suture biological tissue, such as an anatomical valve. The suturing apparatuses can include a suturing device having an elongate shaft having a proximal end and a distal end, one or more tissue grasping arms, and a handle with actuators. The suturing device can further include at least two needles. One of the tissue grasping arms can have at least two suture mounts each loaded with a suture portion. The suture portions on the suture mounts can form a single suture strand. Methods for suturing bodily tissue may be performed with the suturing apparatuses. The tissue grasping arms can grasp tissue therebetween and at least two needles can be deployed toward the suture mounts, engage the suture portions, and be retracted through the tissue. A knot can be tied on the ends of the suture strand retrieved by the needles.

Accordingly, it would be desirable to provide alternative and additional methods, devices, and systems for removing and/or disabling fixation devices that are already installed. At least some of these objectives will be met by the inventions described below.

In accordance with the disclosure, there is provided a cutting mechanism configured for cutting leaflet tissue at a cardiac valve, as set out in claim <NUM>. The present disclosure is directed to systems, methods, and devices configured to effectively cut leaflet tissue at a cardiac valve and thereby enable removal of a cardiac valve fixation device and/or further interventional procedures involving the cardiac valve, such as implantation of a replacement valve.

In one embodiment, a cutting mechanism includes a cutting arm having a length extending along a longitudinal axis, the cutting arm including an actuatable cutting element configured to cut targeted leaflet tissue upon sufficient contact with the targeted leaflet tissue. The cutting mechanism further includes a central hinge disposed at or near a distal end of the cutting arm. One or more grasping arms are connected to the central hinge and each extend therefrom to a respective free end. The one or more grasping arms are rotatable about the central hinge so as to be selectively moveable between a closed position in which the one or more grasping arms are closed substantially against the cutting arm and an open position in which the one or more grasping arms are opened laterally away from the cutting arm by rotating about the central hinge. The cutting mechanism is configured to enable grasping of leaflet tissue between the cutting arm and the one or more grasping arms and to enable the cutting of grasped leaflet tissue via actuation of the cutting element.

Also described herein is a system for cutting leaflet tissue at a cardiac valve which includes a guide catheter having a proximal end and a distal end, wherein the distal end of the guide catheter is steerable to a position above a cardiac valve, and a cutting mechanism. The cutting mechanism is routable through the guide catheter and configured to extend beyond the distal end of the guide catheter. The cutting mechanism is configured to enable grasping of leaflet tissue between the cutting arm and the one or more grasping arms and to enable the cutting of grasped leaflet tissue via actuation of the cutting element.

Also described herein is a method of cutting leaflet tissue at a cardiac valve within a body which includes the steps of providing a system for cutting leaflet tissue, positioning the guide catheter such that the distal end of the guide catheter is positioned near a targeted cardiac valve, extending the cutting mechanism beyond the distal end of the guide catheter, grasping targeted leaflet tissue between the cutting arm and the one or more grasping arms of the cutting mechanism, and actuating the cutting element of the cutting mechanism to cut the grasped leaflet tissue. The targeted cardiac valve may have a fixation device attached to adjacent leaflets of the cardiac valve.

Additional features and advantages of exemplary implementations of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary implementations. The features and advantages of such implementations may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims or may be learned by the practice of such exemplary implementations as set forth hereinafter.

Embodiments described herein are configured to effectively cut leaflet tissue at a cardiac valve and thereby enable removal of a cardiac valve fixation device and/or enable further interventional procedures involving the cardiac valve, such as implantation of a replacement valve.

<FIG> illustrates a cross-sectional view of a human heart from a superior perspective, showing the mitral valve <NUM>, which includes an anterior leaflet <NUM> and a posterior leaflet <NUM>. A clip fixation device <NUM> has been positioned in the mitral valve <NUM> to clip and hold the leaflets <NUM> and <NUM> together at the coapting edges. As explained above, such repair devices are often placed with the intent of reducing mitral valve regurgitation. However, if excessive regurgitation remains following placement of the device <NUM>, or if excessive flow obstruction develops (mitral stenosis), and further interventional procedures are necessary or desired, the fixation device <NUM> may need to be detached from leaflet tissue and/or removed from the mitral valve <NUM>. For example, the fixation device <NUM> may need to be repositioned or removed prior to the placement of a replacement valve.

Conventional techniques for cutting leaflet tissue to remove fixation devices include using a snare wire segment energized with radiofrequency (RF) energy to cut leaflet tissue surrounding the fixation device. However, such techniques suffer from drawbacks such as difficulty in clearly visualizing the anterior leaflet <NUM>. Typically, cutting of the anterior leaflet <NUM> and not the posterior leaflet <NUM> is desired, because cutting of the posterior leaflet <NUM> can result in the free fixation device <NUM> and anterior leaflet <NUM> descending into the left ventricle and obstructing the left ventricular outflow tract (LVOT).

Conventional approaches also risk snaring sub-valvular anatomic structures such as mitral valve chordae tendineae or papillary muscles. Snaring and/or cutting these structures can result in damage to ventricular health and function. Snare wires may also become caught on or in between fixation devices prior to the application of RF energy, which can result in inadvertent transmittance of RF energy to the fixation device(s) (which typically include metal components). This can result in excessive heating in the heart, leading to localized tissue damage, tissue fragmentation and embolization, and excessive coagulation.

Embodiments described herein can provide several benefits to the art. For example, embodiments described herein may allow for the clear visualization of the anterior mitral leaflet during cutting in order to avoid inadvertently cutting the posterior mitral leaflet. Embodiments described herein are also configured to provide effective tissue grasping functionality that can minimize the risk of becoming caught or entangled with sub-valvular structures or the previously implanted fixation device(s). The structures and corresponding functions that enable such benefits are described in more detail below.

Although most of the following description will focus on cutting of the anterior mitral leaflet <NUM>, it will be understood that the same components and features may be utilized, in some applications, to additionally or alternatively target the posterior mitral leaflet <NUM> for cutting. Further, although most of the examples describe the application of a cut that extends laterally across the anterior leaflet <NUM> (see <FIG>), the same components and features described herein may be utilized to cut a targeted leaflet radially rather than laterally. For example, in preparation for placement of a prosthetic replacement mitral valve, the anterior leaflet <NUM> may be cut radially to bisect the leaflet <NUM> and reduce the chance of outflow tract obstruction after a prosthetic replacement valve is implanted.

Moreover, although the examples described herein are provided in the context of cutting leaflet tissue of a mitral valve, one skilled in the art will appreciate that the embodiments described herein are not necessarily limited to use within the mitral valve <NUM>. In other applications, the targeted cardiac valve could be the tricuspid valve, aortic valve, or pulmonic valve for example. More generally, the embodiments described herein may be utilized in other implementations involving removal of a previously implanted or deployed device from tissue.

In addition, although examples may illustrate routing the guide catheter to the mitral valve via a transfemoral/transseptal or transjugular/transseptal approach, other suitable delivery approaches may be used, including radial or transapical approaches.

<FIG> illustrates an exemplary embodiment of a delivery system <NUM> that may be utilized for guiding and/or delivering a cutting mechanism <NUM> to a targeted cardiac valve. In at least one embodiment, the delivery system <NUM> includes a guide catheter <NUM> having a proximal end and a distal end <NUM>. The delivery system may comprise a handle <NUM> positioned on the proximal end of the guide catheter <NUM>. The guide catheter <NUM> may be operatively coupled to a handle <NUM>. The guide catheter <NUM> may be steerable to enable the guiding and orienting of the guide catheter <NUM>, including the distal end <NUM> of the guide catheter <NUM>. For example, the handle <NUM> may include at least one control <NUM> (e.g., a dial, a switch, a slider, a button, etc.) that can be actuated to control the movement and curvature of the distal end <NUM> of the guide catheter <NUM>.

As one example of a steering mechanism, the at least one control <NUM> may be operatively coupled to one or more control lines <NUM> (e.g., pull wires) extending from the handle <NUM> through the guide catheter <NUM> to the distal end <NUM> of the guide catheter (e.g., through one or more lumens in the guide catheter <NUM>). Actuation of the at least one control <NUM> may adjust the tensioning of a control line <NUM> to pull the guide catheter <NUM> in the corresponding direction. <FIG> shows a pair of control lines <NUM>. Alternatively, a handle <NUM> may comprise more than one control <NUM> configured for steering and any number of corresponding control lines. For example, the delivery system <NUM> may be configured to provide bending of the guide catheter <NUM> in multiple planes and/or at multiple bending points along the length of the guide catheter <NUM>.

The control <NUM> and/or other controls disposed at the handle <NUM> may also be utilized to control actuation of various components of the cutting mechanism <NUM>, as explained in more detail below. As shown in <FIG>, the cutting mechanism <NUM> is configured in size and shape so as to be routable through the guide catheter <NUM> and extendable beyond the distal end <NUM> of the guide catheter <NUM>. The cutting mechanism <NUM> may also be retracted back into the guide catheter <NUM>. Control(s) <NUM> may control the cutting mechanism's <NUM> extension through and retraction back into the guide catheter <NUM>. Additionally, or alternatively, the control(s) <NUM> may be configured to provide selective actuation of one or more components of the cutting mechanism <NUM>.

<FIG> illustrates a cross-sectional view of a patient's heart <NUM> from an anterior perspective, showing an exemplary approach for delivering the cutting mechanism to the targeted mitral valve <NUM> using the guide catheter <NUM>. In particular, <FIG> illustrates a transfemoral approach via guide catheter <NUM> (shown for this approach as guide catheter 105a), and an alternative transjugular approach via guide catheter <NUM> (shown for this approach as guide catheter 105b).

In a transfemoral approach, the delivery catheter 105a is inserted into the patient's vasculature at a femoral vein and directed to the inferior vena cava <NUM>. The catheter 105a is passed through the inferior vena cava <NUM> and into the right atrium <NUM>. In the transjugular approach, the delivery catheter 105b is inserted into the patient's vasculature at a jugular vein and directed to the superior vena cava <NUM>. The catheter 105b is passed through the superior vena cava <NUM> and into the right atrium <NUM>. Subsequently, in either approach, the distal end <NUM> of the catheter is pushed across the septum <NUM> so as to be positioned in the left atrium <NUM> superior of the mitral valve <NUM>.

As explained further below, the cutting mechanism <NUM> is then directed partially through the mitral valve <NUM> and partially into the left ventricle <NUM> so that leaflet tissue can be grasped and cut.

<FIG> is an expanded view of the cutting mechanism <NUM>. As shown, the cutting mechanism <NUM> may comprise a cutting arm <NUM> surrounded by at least two grasping arms 210a and 210b. The cutting mechanism <NUM> includes a central hinge <NUM> disposed at the distal end of the device. The grasping arms 210a and 210b connect to the cutting arm <NUM> at the central hinge <NUM> and extend therefrom to respective free ends 215a and 215b.

The grasping arms 210a and 210b may comprise a rigid, semi-rigid, or flexible material. Preferably, at least the tips of the grasping arms 210a and 210b near the free ends 215a and 215b may comprise a flexible material so they are atraumatic if contacted against the ventricular wall or subvalvular structures.

The grasping arms 210a and 210b may have a length of about <NUM> to about <NUM>, more typically about <NUM> to about <NUM>, although smaller or longer lengths may be utilized according to particular application needs. In at least one embodiment, the length of the at least two grasping arms 210a and 210b is adjustable.

<FIG> further shows that the cutting mechanism <NUM> may comprise a cutting element <NUM>. The cutting element <NUM> may be configured to cut a portion of a leaflet grasped by the cutting mechanism <NUM> when the cutting mechanism <NUM> is actuated. In at least one embodiment, the cutting element <NUM> is spring loaded and/or configured to retract into the cutting arm <NUM> when not in use.

The cutting element <NUM> may comprise a sharpened edge, such as a mechanical blade, as shown in <FIG>. Additionally, or alternatively, the cutting element <NUM> may comprise a tapered needle, an active electrosurgical electrode blade configured to provide radio frequency current energy to the portion of the leaflet, a wire loop, or other suitable structure capable of cutting leaflet tissue grasped by the cutting mechanism <NUM>.

The cutting element <NUM> may have a length of at least the majority of the length of the cutting arm <NUM> in order to enable more expedient cutting of the leaflets. In other embodiments, the cutting element may have a length of less than the majority of the length of the cutting arm <NUM>, in order to provide precise cutting and reduce the risk of inadvertent cutting of incorrect tissue.

In some embodiments, the cutting element <NUM> is disposed within the cutting arm <NUM>. For example, the cutting arm <NUM> may comprise a slot through which the cutting element passes <NUM>. The slot may have a greater length than the cutting element <NUM> to allow the cutting element <NUM> to move proximally/distally relative to the cutting arm <NUM>, such as in a reciprocating motion, to aid in cutting grasped leaflet tissue.

The cutting arm <NUM> may comprise a gripping element configured to aid in gripping leaflet tissue in contact with the cutting arm <NUM>. For example, the cutting arm <NUM> may include tines, barbs, one or more coatings, grooves, textured surfaces, and/or other features for increasing the friction of the cutting arm surface to prevent grasped tissue from sliding proximally and/or away from the cutting arm <NUM>.

<FIG> illustrate the exemplary cutting mechanism <NUM> in greater detail, showing actuation and movement of the grasping arms 210a and 210b between an open position and a closed position. <FIG> shows the grasping arms 210a and 210b in an open position, <FIG> shows the grasping arms 210a and 210b in an intermediate position, and <FIG> shows the grasping arms 210a and 210b in a closed position.

<FIG> show that the grasping arms 210a and 210b may rotate laterally away from the cutting arm <NUM> by way of the central hinge <NUM>. In a typical tissue grasping maneuver, the grasping arms 210a and 210b are opened to an angle of about <NUM> to about <NUM> degrees (such as shown in <FIG>), though the grasping arms 210a and 210b may be configured to open to an angle of up to about <NUM> degrees.

The cutting mechanism <NUM> may include a control rod <NUM> that extends through the cutting arm <NUM> (or runs parallel with it) to mechanically couple to a linkage assembly <NUM> of the cutting mechanism <NUM>. The linkage assembly <NUM> is in turn mechanically connected to the grasping arms 210a and 210b. The control rod <NUM> is able to move in the axial direction relative to the cutting arm <NUM>. A proximal end (not shown) of the control rod <NUM> can extend to the handle <NUM> and be operatively connected to one or more controls <NUM> (see <FIG>).

Actuation of the control rod <NUM> moves the control rod <NUM> axially relative to the cutting arm <NUM> to thereby mechanically adjust the linkage assembly <NUM>. Because the linkage assembly <NUM> is connected to the grasping arms 210a and 210b, the axial movement of the control rod <NUM> thereby controls rotation of the grasping arms 210a and 210b towards and away from the cutting arm <NUM>. For example, the control rod <NUM> and linkage assembly <NUM> may be configured to move the grasping arms 210a and 210b toward the cutting arm <NUM> (and toward the closed position) when the control rod <NUM> is moved proximally relative to the cutting arm <NUM>, and to move the grasping arms 210a and 210b away from the cutting arm <NUM> (and toward the open position) when the control rod <NUM> is moved distally relative to the cutting arm <NUM>.

Other embodiments may additionally or alternatively include other actuation mechanisms for moving the cutting mechanism <NUM> between an open position and a closed position. For example, the cutting mechanism <NUM> may be configured to move between open and closed positions based on rotation of the control rod <NUM> and/or based on controlling tension in one or more control wires extending from the cutting mechanism <NUM> to one or more controls <NUM> of the handle <NUM>. In some embodiments, the cutting mechanism <NUM> may be biased toward a "default" position (either the open position or the closed position), and once moved away from the default, biased position, a button, toggle, switch, or other control mechanism can be actuated to trigger release and rapid movement back to the default, biased position.

The shape and length of the at least two grasping arms 210a and 210b shown in <FIG> are merely exemplary. The at least two grasping arms 210a and 210b may be sized and shape to increase mechanical advantage of the at least two grasping arms 210a and 210b to exert tension on leaflet tissue grasped therebetween. In at least one embodiment the grasping arms 210a and 210b are configured to shield the cutting element <NUM> from surrounding cardiac structures. For example, a cover, webbing, or other protective structure may be positioned over the space between the grasping arms 210a and 210b to minimize the risk of the cutting element <NUM> inadvertently contacting anything not grasped between the cutting arm <NUM> and the grasping arms 210a and 210b.

As shown by the illustrated embodiment, the grasping arms 210a and 210b may have a curved profile to better position grasped tissue for cutting. For example, the free ends 215a and 215b may be curved inward toward the cutting arm <NUM>. The free ends 215a and 215b may curve inwards at an angle of about <NUM> to about <NUM> degrees, for example,.

As shown in <FIG>, the grasping arms 210a and 210b may cross over the longitudinal axis of the cutting arm <NUM> as the grasping arms 210a and 210b move into the closed position, and this may be aided in part by the curved shape of the free ends 215a and 215b. This allows the cutting mechanism <NUM> to "over close" and better grasp and stretch leaflet tissue for more effective cutting of the leaflet tissue.

The shape of the cutting element <NUM> may be customized based on a patient's leaflet anatomy and pathology. Additionally, or alternatively, a cross bar <NUM> may be included partially connecting the two grasping arms 210a and 210b. The cross bar <NUM> may function to enhance tissue contact with the cutting arm <NUM> and/or cutting element <NUM>, for example. As shown, the cross bar <NUM> may be disposed so as to be distal of the cutting element <NUM> (i.e., closer to the central hinge <NUM> than the cutting element <NUM>) when the cutting mechanism <NUM> is in the closed position.

<FIG> illustrates an alternative configuration of cutting element <NUM>, which includes a series of consecutive cutting elements <NUM> configured on the cutting arm <NUM>. This configuration includes multiple cutting elements <NUM> can create a "serrated" blade <NUM>, which can improve cutting performance while allowing the user to exert less than normal force during cutting. Normal force may be understood as the force used to make an adequate cut using a single cutting element <NUM>. The dynamics of a beating heart can assist in accomplishing a full and clean cut against blade <NUM>, which can be useful for removing stubborn pieces of leaflet tissue which might remain after an initial cutting attempt. If a strand of tissue remains, the beating of the heart can cause the strand of tissue to move or drag across the blade <NUM> in a dynamic way once its neighboring tissue is cut, which can subsequently aid in completion of the cut and removal of the strand of tissue. In some embodiments, all exposed cutting element edges <NUM> can be sharp to ensure bidirectional serrated cutting Alternatively, portions of the exposed cutting element edges <NUM> can be sharp.

The mitral and tricuspid valve leaflet tissue generally varies in thickness from ~<NUM> thick for generally healthy tricuspid leaflet tissue, to ~<NUM> for thick healthy mitral valve leaflet tissue. Diseased tissue may be thicker than healthy leaflet tissue as diseased tissue can be thickened to <NUM> and greater due to, for example, degenerative valve leaflet tissue or Barlow's disease. In some configurations, the cutting element <NUM> can be configured to cut to a depth sufficient to adequately cut through diseased tissue. A depth of the cutting element <NUM> can range from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, and any combinations or modifications thereof. The cutting depth can be sufficient to cut through diseased tissue, while also shallow enough to avoid inadvertently cutting through tissue which should not be cut.

<FIG> illustrate alternative configurations of the cross bar <NUM>, grasping arms 210a, 210b, and the cutting element <NUM> that may be provided in addition to or as an alternative to the configuration shown in <FIG>. <FIG> illustrates that the cross bar <NUM> may be positioned so as to substantially align with the cutting element <NUM> when the cutting mechanism <NUM> is moved to the closed position. That is, the cross bar <NUM> may be positioned at the same location/height as the cutting element <NUM> so as to directly press tissue against the cutting element <NUM> when the cutting mechanism <NUM> moves into the closed position.

<FIG> illustrates that multiple cross bars <NUM> may be included (shown here as separate cross bars 220a through 220c). It will be appreciated that the cross bar(s) may be disposed at any of the locations along the lengths of the grasping arms 210a, 210b relative to the cutting element <NUM>. For example, one or more cross bars 220a may be positioned above the cutting element <NUM> (i.e., farther from the central hinge <NUM> than the cutting element <NUM>), one or more cross bars 220b may be substantially aligned with the cutting element <NUM>, and/or one or more cross bars 220c may be positioned below the cutting element <NUM> (i.e., closer to the central hinge <NUM> than the cutting element <NUM>).

<FIG> illustrates that cross bars <NUM> need not necessarily be linearly disposed between the grasping arms 210a, 210b and may have, for example, a curved shape (such as cross bar 220d), angular shape (such as cross bar 220e), shape of variable width, or other non-linear and/or variable shape. <FIG> illustrates a configuration that includes a webbing <NUM> disposed between the grasping arms 210a and 210b. The webbing <NUM> may comprise a braided material, sheet, and/or film, for example, that extends across the gap between the grasping arms 210a and 210b. The webbing <NUM> may be formed to be cut-resistant or may be allowed to be cut along with tissue when the cutting element <NUM> is actuated. <FIG> illustrates a configuration where the gap between the grasping arms 210a and 210b is substantially filled so as to form a single, "solid" grasping arm structure. The grasping arm structure may have one or more grooves or indentations for receiving the cutting arm <NUM> and cutting element <NUM>.

<FIG> illustrates another embodiment of a cutting mechanism <NUM>. The cutting mechanism <NUM>, like the cutting mechanism <NUM> described above, may include a cutting arm <NUM>, a cutting element <NUM>, one or more grasping arms <NUM>, a central hinge <NUM>, a control rod <NUM>, and a linkage assembly <NUM>.

The cutting mechanism <NUM> additionally includes an auxiliary arm <NUM> disposed opposite the one or more grasping arms <NUM>. The auxiliary arm <NUM> may be connected to the linkage assembly <NUM> and be configured to rotate about the central hinge <NUM> in response to controlled actuation via the control rod <NUM> in a fashion similar to the grasping arms <NUM>. The auxiliary arm <NUM> includes a cutting element link <NUM> that connects to the cutting element <NUM>. For example, the link <NUM> may extend through the cutting arm <NUM> to connect to the cutting element <NUM>.

The auxiliary arm <NUM> can thus function to move the cutting element <NUM> in response to actuation (via axial movement) of the control rod <NUM>. For example, actuation of the control rod <NUM> can cause the grasping arms <NUM> and the auxiliary arm <NUM> to move toward the closed position. As the auxiliary arm <NUM> closes and gets closer to the cutting arm <NUM>, the link <NUM> pushes against the cutting element <NUM> and causes it to extend out from the cutting arm <NUM>, as shown in <FIG>. Similarly, moving the grasping arms <NUM> and auxiliary arm <NUM> to the open position causes the cutting blade <NUM> to retract toward the cutting arm <NUM>.

In use, the illustrated embodiment beneficially enables the cutting element <NUM> to be housed or substantially housed within the cutting arm <NUM> when the cutting mechanism <NUM> is in the open position, and enables the cutting element <NUM> to automatically extend and be exposed only as the grasping arms <NUM> are closing and targeted tissue is being brought into the cutting arm <NUM> to be cut.

As with the cutting element <NUM>, the cutting element <NUM> can extend out from the cutting arm <NUM> a distance ranging from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, and any combinations or modifications thereof. The cutting depth, or the distance which the cutting element <NUM> extends from the cutting arm <NUM> can be sufficient to cut through diseased tissue, while also shallow enough to avoid inadvertently cutting through tissue which should not be cut.

<FIG> illustrates another embodiment of a cutting element <NUM>. The cutting mechanism <NUM>, like the cutting mechanism <NUM> described above, may include a cutting arm <NUM>, a cutting element <NUM>, one or more grasping arms <NUM>, a central hinge <NUM>, a control rod <NUM>, and a linkage assembly <NUM>.

The cutting mechanism <NUM> additionally includes trauma reducing features. The grasping arms <NUM> which are used to press leaflet tissue into the cutting element <NUM> might become inadvertently caught on the patient's anatomy, so it may be useful to include trauma reducing features such as atraumatic tips <NUM> and flexibility-enhancing features, such as slit cuts <NUM>. Other flexibility-enhancing features may include the grasping arms <NUM> having a tapered cross-section, and/or the grasping arms <NUM> may comprise multiple materials, with a more flexible material disposed towards the distal ends <NUM> of the grasping arms <NUM> to increase flexibility toward the distal ends <NUM> of the grasping arms <NUM>. The multiple materials can include at least two metallic materials, at least two polymeric materials, at least one metallic material with at least one polymeric material, combinations or modifications thereof. For instance, one material can be over molded with another material. In another configuration, one material is bonded, glued, welded, brazed with or otherwise attached to another material.

The grasping arms <NUM> may still maintain their stiffness near the cutting element <NUM> to maintain their effectiveness, though by configuring the distal ends <NUM> of the grasping arms <NUM> to bend during use, damage to the leaflet tissue or chords can be minimized. The slit cuts <NUM> may be equally spaced along the distal ends <NUM> to impart an equal degree of flexibility along the distal ends <NUM>. The slit cuts <NUM> may also be arranged in a pattern where the number and density of slit cuts <NUM> can increase towards the distal ends <NUM> to provide an increasing degree of flexibility towards the atraumatic tips <NUM>. The pattern can include discrete or overlapping slits that are orientated parallel, perpendicular, and/or transverse to a longitudinal axis of a grasping arm <NUM>.

The grasping arms <NUM> can comprise a metallic material such as steel, cobalt, chrome, NITINOL®, titanium, or the like, or a polymeric material, such as poly-L-lactide (PLLA), poly(lactic-co-glycolic acid) (PLGA), Polyether block amide (PEBA), such as PEBAX®, biocompatible composite, combinations and/or modifications thereof, or the like, or the grasping arms <NUM> can be a combination of a metallic material and a polymeric material. <FIG> illustrate examples of various configurations of materials comprising the grasping arms <NUM> comprising material A <NUM> and material B <NUM>. In some examples, material A <NUM> can comprise a metallic material or a polymeric material, as discussed above. Accordingly, material B <NUM> can comprise a metallic material or a polymeric material. Material A <NUM> and material B <NUM> are different materials and can be configured in a sandwich configuration as shown in <FIG>, or they can be arranged next to each other as shown in <FIG>. The materials can be arranged in a manner that imparts a desired stiffness and/or flexibility on the grasping arms <NUM>.

All or a portion of each of the grasping arms <NUM> can also or alternatively have a braided structure <NUM>, as illustrated in <FIG>, and may be laser cut from a tube or a sheet, or made from stamped or formed material. The braided structure <NUM> can have a larger, looser braid at the tips <NUM> in order to impart a desired degree of flexibility. The braided structure <NUM> can become progressively tighter woven and stiffer as the braided structure <NUM> progresses towards the middle of the grasping arms <NUM>. The geometry of the grasping arms <NUM> as shown in <FIG> and <FIG> is curved with an inward bias towards the cutting arm <NUM>, however, in some embodiments, the profile of the grasping arms <NUM> may be curved with an outward bias and flare outward relative to the cutting arm <NUM> in order to match the curvature of the leaflet tissue being cut.

<FIG> illustrate additional views of the cutting mechanism <NUM> to show use of the cutting mechanism <NUM> to grasp and cut leaflet tissue (such as the anterior leaflet <NUM> shown here). Upon routing the cutting mechanism <NUM> to the appropriate position at the mitral valve, the cutting mechanism <NUM> may be moved from the closed position to the open position. Typically, the cutting mechanism <NUM> is positioned so that the grasping arms <NUM> are on the ventricular side of the valve, and then the cutting mechanism <NUM> is actuated to move the grasping arms <NUM> to the open position. As described above, the grasping arms <NUM> may be actuated by moving the control rod <NUM> axially relative to the cutting arm <NUM> to cause the linkage assembly <NUM> to rotate the grasping arms <NUM> outward.

<FIG> shows the cutting mechanism <NUM> in the open position (e.g., with the grasping arms <NUM> open to an angle of about <NUM> degrees) with the grasping arms <NUM> on the ventricular side of the leaflet <NUM>. The cutting mechanism <NUM> may be moved to appropriately position the targeted leaflet <NUM> between the grasping arms <NUM> and the cutting arm <NUM>. Then, as shown in <FIG>, the grasping arms <NUM> may be moved toward the closed position by axially moving the control rod <NUM> relative to the cutting arm <NUM>. Further actuation leads to further closing of the grasping arms <NUM> until the leaflet <NUM> is brought into contact with the cutting element <NUM>, as shown in <FIG>.

In some embodiments, the cutting element <NUM> is connected to the control rod <NUM>, and the control rod <NUM> extends through the cutting arm <NUM>. The cutting element <NUM> may pass through a slit in the cutting arm <NUM>, for example. In such an embodiment, axial movement of the control rod <NUM> causes corresponding axial movement of the cutting element <NUM> relative to the cutting arm <NUM>. This beneficially provides an axial cutting motion of the cutting element <NUM> while the grasping arms <NUM> are moving.

For example, moving the control rod <NUM> proximally may simultaneously close the grasping arms <NUM> and cause the cutting element <NUM> to move proximally, allowing for an effective cutting motion that simultaneously brings the leaflet <NUM> laterally into the cutting element <NUM> while axially moving the cutting element <NUM> to cut the leaflet <NUM>. This can also be utilized to perform a "reciprocating cut" procedure where the cutting element <NUM> reciprocates axially while the grasping arms <NUM> are successively opened and closed to grasp new areas of leaflet tissue.

<FIG> illustrate the cutting element <NUM> while grasping and cutting leaflet tissue from a cross-sectional view across the longitudinal axis of the cutting mechanism. <FIG> beneficially illustrate how the cutting element <NUM> may be utilized to stretch the grasped leaflet tissue (such as the anterior leaflet <NUM>) across the cutting arm <NUM> for effective cutting of the tissue by the cutting element <NUM>.

<FIG> shows the leaflet <NUM> disposed between the cutting arm <NUM> and the grasping arms 210a and 210b as the device approaches the closed position. <FIG> illustrates further closing of the grasping arms 210a and 210b such that the grasping arms 210a and 210b cross the longitudinal axis of the cutting arm <NUM> in an "over closed" fashion. This serves to tighten and stretch the grasped tissue across the cutting side of the cutting arm <NUM> so that it can be effectively cut by contact with the cutting element <NUM>, as shown in <FIG>.

<FIG> also illustrate that the grasping arms 210a and 210b may have a curved or flared cross-sectional shape. Such a shape may correspond beneficially with the shape of the cutting arm <NUM> and may aid in providing the tightening and/or stretching of the grasped leaflet tissue across the cutting arm <NUM>.

<FIG> are perspective views of the exemplary cutting mechanism <NUM> as used to cut leaflet tissue of the mitral valve <NUM>. An interventional fixation device <NUM> creates a first and second orifice between the anterior mitral leaflet <NUM> and the posterior mitral leaflet <NUM> by approximating the adjacent leaflets <NUM> and <NUM>. As shown, the distal end <NUM> of the guide catheter <NUM> has been extended through the septum <NUM> of the heart. The cutting mechanism <NUM> may be routed through the guide catheter <NUM> so as to extend through an orifice of the mitral valve <NUM> and be at least partially disposed on a ventricular side of the valve <NUM>.

The grasping arms may then be actuated to move the cutting mechanism <NUM> to the open position. The cutting mechanism <NUM> is then positioned so that leaflet tissue, such as tissue of the anterior leaflet <NUM>, resides between the grasping arms and the cutting arm. The cutting mechanism <NUM> is then moved to the closed position to grasp the leaflet tissue between the cutting arm and the grasping arms. The leaflet tissue may be secured by the grasping arms on a ventricular side of the mitral valve <NUM> and by the cutting arm on the atrial side of the mitral valve <NUM>. With the application of some clamping force, the grasping arms can stretch the leaflet tissue across the cutting arm thereby reducing the thickness of the secured leaflet tissue at that location, and thereby better enable the cutting element to cut through the entire thickness of the secured leaflet tissue.

As shown in Figure 4C, the cutting mechanism <NUM> may be advanced through the anterior mitral leaflet <NUM> by repeated repositioning of the cutting mechanism <NUM> and repeated actuation of the grasping arms. Additionally, or alternatively, the cutting mechanism <NUM> may be advanced through the anterior leaflet <NUM> by partially actuating the at least two grasping arms (e.g., to an open angle of about <NUM> to about <NUM> degrees), dynamically positioning the cutting mechanism <NUM>, and moving or dragging the cutting mechanism <NUM> along the anterior mitral leaflet <NUM>.

Claim 1:
A cutting mechanism (<NUM>) configured for cutting leaflet tissue at a cardiac valve (<NUM>), the cutting mechanism comprising:
a cutting arm (<NUM>, <NUM>) having a length extending along a longitudinal axis, the cutting arm including an actuatable cutting element (<NUM>, <NUM>) configured to cut targeted leaflet tissue upon sufficient contact with the targeted leaflet tissue;
a central hinge (<NUM>, <NUM>) disposed at or near a distal end of the cutting arm;
one or more grasping arms (210a, 210b, <NUM>) each connected to the central hinge and extending therefrom to a respective free end (215a, 215b), the one or more grasping arms being rotatable about the central hinge so as to be selectively moveable between
a closed position wherein the one or more grasping arms are closed substantially against the cutting arm, and
an open position wherein the one or more grasping arms are opened laterally away from the cutting arm by rotating about the central hinge,
wherein the cutting mechanism is configured to enable grasping of leaflet tissue between the cutting arm and the one or more grasping arms and to enable the cutting of grasped leaflet tissue via actuation of the cutting element.