Patent Description:
<CIT> and applications <CIT> and <CIT>describe a variety of approaches for affixing a constricting cord to a cardiac valve annulus or another anatomic annulus, and constricting a diameter of that cord. In particular, patent <CIT> explains that after constricting the cord, two segments of the cord are fastened together (e.g., using a knot, fastener, or adhesive) to prevent the annulus from expanding again. The cord may then be cut at a point that is proximal with respect to the fastening point. But the prior art approaches for fastening and cutting the cord were sub-optimal for a number of reasons. For example, the prior art approaches for tying a knot adjacent to the annulus were time-consuming and labor-intensive; the prior art crimp-based fasteners had to be relatively large in order to exert enough force on the cord to prevent slippage reliably; and the prior art approaches for cutting the cord were labor-intensive.

Also, <CIT> discloses another system and associated method for manipulating tissues and anatomical or other structures in medical applications for the purpose of treating diseases or disorders or other purposes, wherein the system includes a delivery device configured to deploy and implant anchor devices for such purposes. Further, <CIT> discloses an apparatus, comprising a handle assembly, and elongated housing extending distally from the handle assembly and a tool assembly detachably connected to a distal end of the body portion and remotely operable from the handle, wherein the tool assembly enables a surgeon to compress and maintain a securing member upon suture material in a body cavity and also provides means to cut unsecured suture material which extends from the compressed securing member.

Further devices and techniques for affixing a constricting cord to a cardiac valve annulus or another anatomic annulus and for constricting a diameter of that cord are known from <CIT>, <CIT>, and <CIT>.

In view of the above background, the present invention is defined by an apparatus for reducing a diameter of a cord according to claim <NUM>. Further advantageous embodiments are described in the dependent claims.

An aspect of the invention is thus directed to an apparatus for reducing a diameter of a cord that has been previously affixed to an annulus. The apparatus comprises a housing having a distal portion and a distal end. The apparatus also comprises a shelf positioned in the distal portion of the housing that extends in a distal-to-proximal direction, the shelf having an upper surface, a lower surface, and a shelf opening that runs between the upper and lower surfaces of the shelf. The apparatus also comprises a cutting element positioned above the shelf and arranged so that the cutting element can slide in the distal-to-proximal direction with respect to the shelf, the cutting element having a flat body with an upper surface, a lower surface, and an opening that passes between the upper and lower surfaces of the cutting element, the opening of the cutting element having (a) a proximal portion that is dimensioned so that two segments of the cord can slide freely through the proximal portion and (b) a slit shaped distal portion with sharp edges, wherein the slit shaped distal portion is oriented in the distal-to-proximal direction. The apparatus also comprises a fastener positioned at the distal end of the housing, the fastener having an opening. The fastener is movable from a first state in which the cord is free to slide through the opening in the fastener to a second state in which the cord is locked in place.

In some embodiments of the apparatus, the fastener, the shelf, and the cutting element are configured such that the cord can be threaded through the opening in the fastener when the fastener is in the first state so that that after the fastener is moved to the second state, the cord will be arranged in a pre-cutting position in which the cord passes above a portion of the cutting element that is distally beyond the opening of the cutting element, and then passes through the opening of the cutting element and through the opening in the shelf. In these embodiments, the cutting element is configured such that when the cord is arranged in the pre-cutting position, movement of the cutting element in the proximal direction will cause the slit shaped distal portion of the opening of the cutting element to move in a proximal direction until the slit shaped distal portion reaches the cord and cuts the cord.

Some embodiments of the apparatus further comprise a shaft that runs in the distal-to-proximal direction. The shaft is affixed to the cutting element so that pulling the shaft in a proximal direction will pull the cutting element in a proximal direction.

In some embodiments of the apparatus, the upper surface of the shelf lines up with the upper surface of the fastener so that the upper surface of the fastener extends a sliding platform provided by the shelf. In some of these embodiments, the cutting element is configured to slide over both the shelf and a portion of the upper surface of the fastener. In some of these embodiments, the distal end of the shelf has a first aligning feature (e.g., a notch), and the proximal end of the fastener has a second aligning feature (e.g., a protrusion) that matches the first aligning feature.

In some embodiments of the apparatus, the opening of the cutting element tapers down smoothly in a distal direction from the proximal portion of the opening of the cutting element towards the slit shaped distal portion of the opening of the cutting element.

In some embodiments of the apparatus, the slit shaped distal portion is formed by laser cutting the flat body of the cutting element to form a first slit having a width of <NUM>-<NUM>, and subsequently swaging the edges of the first slit towards each other to reduce the width of the first slit.

As explained in <CIT>,an implant that includes the distal loop portion of a constricting cord can be affixed to an annulus of a cardiac valve or another anatomic annulus. After a sufficiently strong bond is achieved between the implant and the annulus, constricting the cord will reduce the diameter of the annulus. Some preferred embodiments of the implant rely on tissue ingrowth to strengthen the bond between the implant and the annulus. In these embodiments, the constricting step is not performed immediately after the implant has been implanted. Instead, a significant waiting period (e.g., <NUM>-<NUM> months) elapses between the implantation step and the constricting step, in order to allow sufficient time for ingrowth to occur. During that waiting period, tissue ingrowth of the adjacent soft tissue into the implant strengthens the bond between the implant and the annulus. Once the tissue ingrowth process has strengthened the bond sufficiently (i.e., to the point where it will withstand constricting with a sufficient level of confidence), the constricting cord is constricted so as to reduce the diameter of the annulus. In other embodiments, the attachment mechanism of the implant may be sufficiently strong to withstand constricting immediately after the implant has been implanted, in which case the constricting cord may be constricted immediately after the implant is implanted.

Two proximal portions (or segments) of the constricting cord run from outside the patient's body to the implanted distal loop portion of the constricting cord. As explained in <CIT>, constriction of the constricting cord may be implemented by sliding a push-tube down over the proximal portions of the constricting cord until the distal end of the push-tube arrives at the distal loop portion of the constricting cord (i.e., the loop-shaped portion which has been affixed to the annulus). Because the proximal portions of the constricting cord extend through the patient's vasculature between the constricting implant and an exit point, those proximal portions can serve as a guide wire over which the push-tube can be guided to its destination. When the push-tube arrives at the distal loop portion of the constricting cord and is pushed in a distal direction, pulling the proximal portions of the constricting cord in a proximal direction will constrict the annulus, thereby reducing the circumference of the annulus. The distal ends of the proximal portions of the constricting cord are then fastened together to prevent the annulus from expanding again. The proximal portions of the constricting cord can then be clipped at a point that is proximal to the place where they are fastened together.

The remainder of this application describes a variety of approaches for fastening the distal ends of the proximal portions of the constricting cord together.

<FIG> depicts the two primary components of a fastener <NUM>/<NUM> that may be used to fasten the distal ends of the proximal portions of the constricting cord together. More specifically, the two primary components of the fastener are the housing <NUM> and the sliding member <NUM>. <FIG> depicts a side view of the housing <NUM> as viewed from a point that is distally beyond the distal end of the housing <NUM>. The housing has an upper wall <NUM> and a lower wall <NUM> with a channel <NUM> disposed between the upper wall <NUM> and the lower wall <NUM>. The channel <NUM> has a distal end <NUM>. In the illustrated embodiment, the upper wall <NUM> and the lower wall <NUM> are both flat and are parallel to each other; and the housing also has sidewalls <NUM> that run between the upper wall <NUM> and the lower wall <NUM> to form a rigid structure. In the illustrated embodiment, the sidewalls <NUM> are also flat and parallel to each other. And in the illustrated embodiment, an extension portion 104X of the lower wall <NUM> extends distally beyond the distal end of the channel <NUM>. This extension portion 104X has an opening <NUM>. In some preferred embodiments, the area of this opening <NUM> is at least <NUM><NUM>. In alternative embodiments, the area of this opening <NUM> is between <NUM> and <NUM><NUM>. Suitable materials for forming the housing <NUM> include cobalt chromium alloys (including but not limited to MP35N, L605, Elgiloy, etc.), surgical stainless steel (including but not limited to <NUM> ss, <NUM> ss, etc.), and other biocompatible metals. In some preferred embodiments, the housing <NUM> is dimensioned so that the channel <NUM> is <NUM> long (in a proximal-to-distal direction) <NUM> wide, and <NUM> tall; and so that the extension portion 104X extends <NUM> distally beyond the distal end of the channel <NUM>.

The sliding member <NUM> has an upper surface <NUM> and a lower surface <NUM> (shown in <FIG>) and the sliding member <NUM> has an opening <NUM> that runs between the upper surface <NUM> and the lower surface <NUM>. In some preferred embodiments, the area of this opening <NUM> is at least <NUM><NUM>. In alternative embodiments, the area of this opening <NUM> is between <NUM> and <NUM><NUM>. The opening <NUM> has a distal end. Preferably, the edges of the channel <NUM> of the housing and the opening <NUM> of the sliding member are not sharp, to reduce the chance of damaging the cord. Suitable materials for forming the sliding member <NUM> include any of the materials listed above in connection with the housing <NUM>. In some preferred embodiments, the sliding member <NUM> is <NUM> long (in a proximal-to-distal direction), <NUM> high, and <NUM> wide; and the distal end of the sliding member <NUM> (which prevents the sliding member <NUM> from entering the channel <NUM> in the housing) is <NUM> wide. Of course, if any of the dimensions of the housing <NUM> deviates from the dimensions specified above, corresponding modifications to the dimensions of the sliding member <NUM> should be made to maintain the interactions between those two components described herein.

<FIG> depict one preferred approach for assembling a subassembly that retains the sliding member <NUM> at an initial position with respect to the housing <NUM> prior to deployment of the fastener.

As seen in <FIG>, the lower wall <NUM> of the housing <NUM> has a through hole <NUM>, and the sliding member has a through hole <NUM>. In some preferred embodiments, the diameter of these through holes is between <NUM> and <NUM>, and in some preferred embodiments, the diameter of these through holes is about <NUM>. The sliding member <NUM> and the housing <NUM> are configured with respect to each other so that before the subassembly is assembled, the sliding member <NUM> is free to slide in a proximal direction with respect to the housing <NUM> until the through hole <NUM> of the housing lines up with the through hole <NUM> of the sliding member as depicted in <FIG>. At this point, a wire <NUM> is threaded through the through holes <NUM>, <NUM> as seen in <FIG>, which are top and bottom views, respectively. Suitable materials for this wire <NUM> include any of the materials listed above in connection with the housing <NUM>, and suitable diameters for this wire <NUM> range from <NUM> to <NUM>. In some preferred embodiments, the wire <NUM> has a diameter of <NUM>.

Note that when the housing <NUM> and the sliding member <NUM> are lined up at this position, the opening <NUM> of the housing will line up with the opening <NUM> of the sliding member, as seen in <FIG>.

The upper end of the wire <NUM> is then welded to the upper surface <NUM> of the sliding member <NUM> at weld point <NUM> (as seen in <FIG>); and the lower end of the wire <NUM> is welded to the bottom of the housing <NUM> at weld point <NUM> (as seen in <FIG>). Welding the upper and lower ends of the wire <NUM> to the upper surface <NUM> of the sliding member <NUM> and the bottom of the housing <NUM>, respectively, forms a first shear pin <NUM> (shown in <FIG>) that holds the sliding member <NUM> at a fixed position with respect to the housing <NUM> (referred to herein as the "initial position" ) until the first shear pin <NUM> is sheared by a force that exceeds a first threshold. In some embodiments, the first threshold is between <NUM> and <NUM> N. Note that while welding is the preferred approach for forming the first shear pin <NUM>, alternative approaches that will be apparent to persons skilled in the relevant arts may also be used to form the shear pin <NUM> that holds the sliding member <NUM> at a fixed position with respect to the housing <NUM>.

A second member <NUM> is then positioned adjacent to the proximal end of the sliding member <NUM> and a second shear pin <NUM> (shown in <FIG>) is affixed between the second member <NUM> and the sliding member <NUM>. One approach for forming this second shear pin <NUM> is depicted in <FIG>. In <FIG>, the lower end of a second wire <NUM> is welded to the second member <NUM> at weld point <NUM>. Subsequently, the upper end of the second wire <NUM> is threaded through the hole <NUM> (shown in <FIG>) in the sliding member <NUM>, as depicted in <FIG>. The upper end of the second wire is then welded on to the sliding member <NUM> at weld point <NUM>, as depicted in <FIG> is a bottom view of the subassembly at this point, and <FIG> depicts plan and cross section views of the subassembly at this point. Suitable materials for both the second member <NUM> and the second wire <NUM> include any of the materials listed above in connection with the housing <NUM>, and suitable diameters for the second wire <NUM> range from <NUM> to <NUM>. In some preferred embodiments (e.g., those in which the first wire <NUM> has a diameter of <NUM>), the second wire <NUM> has a diameter of <NUM>. As will be appreciated by persons skilled in the relevant arts, any variations to the dimensions of the first wire <NUM> should be accompanied by a corresponding variation to the dimensions of the second wire <NUM> to ensure that the first shear pin <NUM> will always shear before the second shear pin <NUM>.

The second shear pin <NUM> maintains the connection between the second member <NUM> and the sliding member <NUM> as long as the pulling force on the second shear pin <NUM> in a proximal direction remains below a second threshold (while the sliding member <NUM> is held at a fixed position). In addition, the second shear pin <NUM> is configured to shear when the pulling force exceeds the second threshold. Shearing of the second shear pin will disconnect the second member <NUM> from the sliding member <NUM>. In some preferred embodiments, the second threshold is at least double the first threshold. In some embodiments, the second threshold is between <NUM> and <NUM> N. Shaft <NUM> (shown in <FIG>) is affixed to the second member <NUM> and is used to apply a pulling force to the second member <NUM> in a proximal direction. Suitable materials for the shaft <NUM> include any of the materials listed above in connection with the housing <NUM>.

The two shear pins <NUM>, <NUM> described above are best seen in the cross section view of <FIG>. More specifically, the first shear pin <NUM> holds the sliding member <NUM> at its fixed initial position with respect to the housing <NUM> until the first shear pin <NUM> is sheared (as described below in connection with <FIG>); and the second shear pin <NUM> connects the sliding member <NUM> to the second member <NUM> until the second shear pin <NUM> is sheared by a force that exceeds a second threshold (as described below in connection with <FIG>). Note that while welding is the preferred approach for forming the second shear pin <NUM>, alternative approaches that will be apparent to persons skilled in the relevant arts may also be used to form the shear pin <NUM> that holds the sliding member <NUM> at a fixed position with respect to the second member <NUM>. Notably, when the configuration depicted in <FIG> is used, the shaft <NUM> can be used to hold the entire subassembly <NUM>-<NUM> in position with respect to the tool <NUM> described below in connection with <FIG>.

In some alternative embodiments (not shown) instead of affixing the shaft <NUM> to the second member <NUM> and connecting the second member <NUM> to the sliding member <NUM> using a shear pin <NUM> (as described above in connection with <FIG>), the pulling shaft <NUM> may be connected directly to the proximal end of the sliding member <NUM> (e.g., by welding). In these embodiments, a weakened region is preferably designed into the distal and of the pulling shaft <NUM>, so that when the pulling force exerted on the pulling shaft <NUM> exceeds a threshold, the pulling shaft <NUM> will break at the weakened region. One way to create this weakened region is to use the heat effect to modify the properties of the metal pulling shaft <NUM>. Optionally, a single step of welding may be used to simultaneously attach the shaft <NUM> to the sliding member <NUM> and introduce the heat effect into the distal portion of the shaft <NUM>.

<FIG> show how the subassembly <NUM>-<NUM> (depicted in <FIG>) can be used to constrict the diameter of an annulus. Turning first to <FIG>, the subassembly <NUM>-<NUM> is loaded into the distal end of a tool <NUM>. As explained above, the proximal portions <NUM> of the constricting cord <NUM> run through the patient's vasculature between the distal loop portion <NUM> of the constricting cord <NUM> and an exit point, so that those proximal portions can serve as a guide wire over which a push-tube can be guided to its destination. The body of the tool <NUM> serves as this push tube. The portions of the constricting cord <NUM> beyond the exit point are threaded (e.g., using a pre-installed guiding thread, not shown) through the openings <NUM>, <NUM> of the subassembly <NUM>-<NUM> so that those portions of the cord follow the path depicted in <FIG>. The tool <NUM> is then advanced in a distal direction until the subassembly <NUM>-<NUM> arrives in the vicinity of the annulus, as depicted in <FIG>. Optionally, the shaft of the tool <NUM> can include a steerable section implemented, e.g., using any of a variety of steerable catheter mechanisms that are well known to persons skilled in the relevant arts.

The tool <NUM> is then advanced further in a distal direction until the subassembly <NUM>-<NUM> arrives at the distal loop portion <NUM> of the constricting cord that has been previously affixed to the annulus, as depicted in <FIG>.

After the subassembly <NUM>-<NUM> reaches this position, the distal loop portion <NUM> of the constricting cord is constricted by pulling the proximal ends of the constricting cord <NUM> while the tool <NUM> holds the subassembly <NUM>-<NUM> in place. This constriction is depicted in <FIG>, (which shows how the diameter of the distal loop portion <NUM> of the constricting cord is reduced when the proximal portions <NUM> of the constricting cord are pulled in a proximal direction through the tool <NUM>) and <FIG> (which is a detail of <FIG>). And because the distal loop portion <NUM> of the constricting cord is affixed to the annulus, the diameter of the annulus will also be reduced.

During constriction of the cord <NUM>, there will be significant tension on the cord. This tension will pull the regions of the distal loop portion <NUM> of the cord on either side of the opening <NUM> in the housing <NUM> and the opening <NUM> in the sliding member <NUM> apart from each other (limited by the confines of the openings <NUM> and <NUM>). As a result, if the proximal portions <NUM> happen to be twisted adjacent to the interface with the distal loop portion <NUM> when the subassembly <NUM>-<NUM> reaches the annulus, the tension will cause the twists to move in a proximal direction along the proximal portions <NUM> of the cord until the twists move proximally beyond the region that will ultimately be clipped together (as described below in connection with <FIG>). This is advantageous because it improves the repeatability and reliability of the clip fastening procedure.

Note that while the proximal ends of the constricting cord <NUM> are being pulled in a proximal direction, it is important for the tool <NUM> to hold the subassembly <NUM>-<NUM> in place. This may be accomplished, for example, by applying a force in a distal direction on the body of the tool <NUM> so that the distal end <NUM> of the tool will transmit that force onto the housing <NUM> portion of the subassembly <NUM>-<NUM>, so that the subassembly <NUM>-<NUM> will remain in place while the proximal ends of the constricting cord <NUM> are being pulled (as best seen in <FIG>).

After the diameter of the annulus has been constricted as described above, tension is maintained on the proximal ends of the constricting cord <NUM>, and a force in a distal direction is applied to the housing <NUM> by the tool <NUM> until deployment of the fastener <NUM>/<NUM> (described below in connection with <FIG>) is complete.

<FIG> depicts the fastener <NUM>/<NUM> in its initial state, which is the same initial state depicted in <FIG>. In this initial state, both of the shear pins <NUM>, <NUM> are intact. While the housing <NUM> is held in place by the tool <NUM>, a pulling force in a proximal direction is applied to the shaft <NUM> e.g., using any appropriate mechanism (not shown) disposed at the proximal end of the tool <NUM>. The shaft <NUM> transmits this pulling force to the second member <NUM>. Because the second shear pin <NUM> is still intact at this point in the sequence, the pulling force that is being applied to the shaft <NUM> will be transmitted to the sliding member <NUM>.

As long as the pulling force that is being applied to the shaft <NUM> remains below the threshold force for shearing the first shear pin <NUM>, the first shear pin <NUM> will hold the sliding member <NUM> at the initial position with respect to the housing <NUM>. But once the pulling force exceeds the threshold for shearing the first shear pin <NUM>, that shear pin <NUM> will shear, and the sliding member will begin to slide in a proximal direction with respect to the housing <NUM>, as depicted in <FIG>.

The pulling force is maintained on the shaft <NUM>. The shear pin <NUM> continues to transmit that force onto the sliding member <NUM>. Because the shear pin <NUM> has already been sheared, the sliding member <NUM> will continue to slide in a proximal direction with respect to the housing until the sliding member <NUM> reaches the position depicted in <FIG> with respect to the housing <NUM>. This position of the sliding member <NUM> is referred to herein as the "final position. " The sliding member <NUM> cannot continue proximally beyond the final position because the distal end <NUM> of the sliding member <NUM> is too large to fit into the channel <NUM> in the housing. More specifically, as seen in <FIG>, the width of the channel <NUM> is defined by the first and second inner sidewalls <NUM>. And in the illustrated embodiment, the sliding member <NUM> has a T-shaped distal end <NUM> with a width that is larger than the width of the channel <NUM>.

In the illustrated embodiment, the sliding member <NUM> also has a pair of spring arms <NUM> that, prior to this point in the sequence, were compressed together by the sidewalls <NUM> of the housing <NUM>, with the distal end of each of the spring arms <NUM> disposed within the channel <NUM>. But once the sliding member <NUM> arrives at the final position depicted in <FIG>, the spring arms <NUM> will exit the proximal end of the channel <NUM> and automatically spring outward until the spring arms <NUM> reached their relaxed state. In their relaxed state, the distance between the outermost portions of the two spring arms <NUM> will exceed the width of the channel <NUM> (shown in <FIG>), which prevents the sliding member <NUM> from sliding back in a distal direction with respect to the housing <NUM>.

Because the sliding member <NUM> cannot continue proximally beyond the final position (due to the distal end <NUM> of the sliding member <NUM>) and cannot slide back in a distal direction (due to the operation of the spring arms <NUM>), once the sliding member <NUM> reaches its final position, the sliding member <NUM> will be immobilized at that position. In alternative embodiments, different approaches that will be apparent to persons skilled in the relevant arts may be used to immobilize the sliding member <NUM> when it reaches the final position. For example, instead of having a T-shaped distal end, a single protrusion may be disposed at the distal end of the sliding member <NUM> that is shaped and positioned to block the sliding member <NUM> from moving proximally beyond the final position. Similarly, instead of relying on a pair of spring arms <NUM> to prevent the sliding member <NUM> from moving backwards in a distal direction from the final position, a single spring arm may be used to achieve the same result.

As long as the pulling force on the shaft <NUM> remains below the second threshold (i.e. the threshold required to shear the second shear pin <NUM>), the second shear pin <NUM> will prevent the second member <NUM> from further movement in the proximal direction. But the second member <NUM> is not part of the fastener that will remain behind, and must be disconnected and removed. This is accomplished by increasing the pulling force on the shaft <NUM> to increase the corresponding pulling force exerted by the second member <NUM> on the second shear pin <NUM>. When the pulling force exceeds the second threshold, the second shear pin <NUM> will shear, and the second member <NUM> will begin to move in a proximal direction, as depicted in <FIG>. Continued application of pulling force on the shaft <NUM> will move the second member <NUM> further away from the sliding member <NUM> (which is now locked to the housing <NUM> at the final position), as seen in <FIG>. Advantageously, the design described above using two shear pins <NUM>, <NUM> with distinct shear thresholds provides excellent consistency and repeatability so that a repeatable level of force will shear each of those shear pins, and so that the first shear pin <NUM> will always shear before the second shear pin <NUM>.

Note that after the second shear pin <NUM> has sheared and the second member <NUM> has pulled away from the sliding member <NUM>, the cord <NUM> (which is preferably held taut during this portion of the procedure e.g., by pulling the proximal ends of the proximal portions <NUM> of the cord <NUM> in a proximal direction) retains the fastener <NUM>/<NUM> in the distal end of the tool <NUM> until the cord <NUM> is either cut by the cutting blade <NUM> (as described below in connection with <FIG>) or released.

Having explained the interaction between the sliding member <NUM> and the housing <NUM> in connection with <FIG>, we return to the explanation of how the sliding member <NUM> and the housing <NUM> interact with the constricting cord <NUM> to fasten that cord in its constricted state.

The last time the constricting cord <NUM> was mentioned in this application was in connection with <FIG>, at which point the proximal portions <NUM> of the constricting cord were threaded through the openings <NUM>, <NUM> of the subassembly <NUM>-<NUM>, and the distal loop portion <NUM> of the constricting cord was subsequently constricted by pulling the proximal ends of the constricting cord <NUM> while the tool <NUM> held the subassembly <NUM>-<NUM> in place.

<FIG> explain how moving the sliding member <NUM> from its initial position to its final position (following the sequence described above in connection with <FIG>) causes the fastener <NUM>/<NUM> to lock the constricting cord in place after the distal loop portion <NUM> of the constricting cord is constricted. In this sequence of figures, the body of the tool <NUM> is omitted for clarity.

<FIG> depicts the path of the constricting cord <NUM>, <NUM> through the opening <NUM> in the sliding member <NUM> when the sliding member <NUM> is at the initial position (which corresponds to the position depicted in <FIG> in the sequence described above). <FIG> is similar to <FIG>, except that the portion of the constricting cord that passes beneath the housing <NUM> and sliding member <NUM> is shown in dashed lines. <FIG> depicts a side section detail that shows how the cord <NUM>, <NUM> passes through the opening <NUM> in the housing <NUM> and through the opening <NUM> in the sliding member <NUM> when the sliding member <NUM> is at its initial position. At this point in the sequence, the first and second shear pins <NUM>, <NUM> are still intact. In addition, the diameter of the distal loop portion <NUM> of the constricting cord can still be adjusted by progressively pulling the proximal portions of the constricting cord <NUM> in a proximal direction while the fastener <NUM>/<NUM> is held in place by the tool <NUM>.

<FIG> depicts the path of the constricting cord <NUM>, <NUM> through the opening <NUM> in the housing <NUM> and the opening <NUM> in the sliding member <NUM> after the sliding member <NUM> has been moved to the final position (which corresponds to the position depicted in <FIG> in the sequence described above). <FIG> is similar to <FIG>, except that the path of the constricting cord that passes through both of those openings is shown in dashed lines. <FIG> is a detailed view of <FIG>, and <FIG> depicts a side section detail that shows how the cord <NUM>, <NUM> passes through the opening <NUM> in the housing <NUM> and through the opening <NUM> in the sliding member <NUM> when the sliding member <NUM> is at its final position.

At this point in the sequence (as best seen in <FIG>), the distal end of the opening <NUM> in the sliding member <NUM> has entered the channel (which is bounded by the upper wall <NUM> and the lower wall <NUM> of the housing <NUM>) and has pushed a first part <NUM> of the cord to a position at which the first part <NUM> of the cord is squeezed between the upper surface <NUM> of the sliding member <NUM> and the upper wall <NUM> of the housing <NUM>, and has also pushed a second part <NUM> of the cord to a position at which the second part <NUM> of the cord is squeezed between the lower surface <NUM> of the sliding member <NUM> and the lower wall <NUM> of the housing <NUM>. In some preferred embodiments, the sliding member <NUM> and the housing are shaped and dimensioned so that the squeezing of the first and second parts <NUM>, <NUM> of the cord will be sufficient to hold the cord in place when a portion of the cord that remains outside the housing is pulled by a <NUM> N force.

Assume, for example, that the nominal diameter of the cord <NUM> is <NUM>; that the distal end of the opening <NUM> in the sliding member is <NUM> away, in a proximal direction, from the distal end of the channel; that the gap between the upper wall <NUM> of the housing <NUM> and the upper surface <NUM> of the sliding member <NUM> is <NUM>; and that the gap between the lower wall <NUM> of the housing <NUM> and the lower surface <NUM> of the sliding member <NUM> is also <NUM>. When these dimensions are used, the first part <NUM> of the cord is squeezed between the upper surface <NUM> of the sliding member <NUM> and the upper wall <NUM> of the housing <NUM> down from its original nominal diameter of <NUM> to <NUM>. Similarly, the second part <NUM> of the cord is squeezed between the lower surface <NUM> of the sliding member <NUM> and the lower wall <NUM> of the housing <NUM> down from its original nominal diameter of <NUM> to <NUM>. In this situation, the squeezing force that is applied to those two parts <NUM>, <NUM> of the cord is sufficient to prevent the cord <NUM> from slipping with respect to the fastener <NUM>/<NUM>.

Note that in this example, the first distance between the upper wall of the housing and the lower wall of the housing will exceed the second distance between the upper surface of the sliding member and the lower surface of the sliding member by <NUM> (because a <NUM> gap appears both above and below the sliding member). But in alternative embodiments, the first distance will exceed the second distance by between <NUM> and <NUM>, or between <NUM> and <NUM>. Note also that in this example, the distal end of the opening <NUM> in the sliding member is <NUM> away, in a proximal direction, from the distal end of the channel. But in alternative embodiments, the distal end of the opening <NUM> in the sliding member is at least <NUM> away, in a proximal direction, from the distal end of the channel.

When the nominal diameter of the cord is larger or smaller than <NUM>, the various dimensions should be scaled up or down accordingly. For example, if the cord has a nominal diameter of D, the area of the opening <NUM> in the sliding member <NUM> should be at least <NUM> times D<NUM>; the distal end of the opening <NUM> in the sliding member <NUM> should be at least one half D away, in a proximal direction, from the distal end <NUM> of the channel; and the first distance should exceed the second distance by between <NUM> times D and <NUM> times D, or between <NUM> times D and one half D.

<FIG> depicts the fastener <NUM>/<NUM> and cord <NUM>, <NUM> in the same state as in <FIG>, and also shows additional components disposed at the distal end of the tool <NUM> that were omitted from <FIG> for clarity. More specifically, <FIG> depicts the distal end <NUM> of the tool <NUM>, and a cutting blade <NUM> (also referred to herein as a cutting element) that is used to cut the proximal portions of the cord <NUM> after the fastener <NUM>/<NUM> has fastened the cord into its reduced-diameter state.

<FIG> is a cutaway view of the tool <NUM> that reveals additional details of the interrelationship between the cutting blade <NUM> and the proximal portions of the cord <NUM>. More specifically, the cutting blade <NUM> has a flat body with an upper surface, a lower surface, and an opening <NUM> that passes between the upper surface and the lower surface. The proximal portions of the cord <NUM> pass above the distal end of the cutting blade <NUM>, through the opening <NUM>, and continue in a proximal direction beneath the proximal end of the cutting blade <NUM>. A shaft <NUM> is affixed to the cutting blade <NUM> so that pulling the shaft <NUM> in a proximal direction will pull the cutting blade <NUM> in a proximal direction.

<FIG> depicts the same components shown in <FIG> at a point in time that corresponds to <FIG> (i.e., after the second member <NUM> has pulled away in a proximal direction from the sliding member <NUM>).

<FIG> depict the next steps in the sequence, during which the proximal portions of the cord <NUM> are cut. A cutting blade <NUM> is slidably positioned on a shelf <NUM> so that the cutting blade <NUM> can slide in a distal to proximal direction with respect to the shelf <NUM>. The shelf <NUM> has an upper surface and a lower surface and a shelf opening or orifice <NUM> that runs between the upper surface and the lower surface of the shelf <NUM>. Cutting is accomplished by first ensuring that the proximal portions of the cord <NUM> are taut (e.g., by pulling the proximal ends of the proximal portions <NUM> in a proximal direction while pushing the body <NUM> in a distal direction) and subsequently pulling the proximal end of the shaft <NUM> in a proximal direction so that the shaft <NUM> will pull the cutting blade <NUM> in a proximal direction. The interaction between the various components involved in cutting is described in greater detail immediately below.

<FIG> depicts the position of the relevant components just prior to cutting of the proximal portions <NUM> of the cord. At this point in time, the opening <NUM> in the cutting blade coincides with or is aligned with the shelf orifice <NUM>, and the proximal portions <NUM> of the cord are threaded through the various components as follows: Immediately after exiting the distal end of the housing <NUM>, the cord makes a U-tum and passes over a saddle <NUM> with a smooth concave lower surface. The cord then passes above a portion of the cutting blade <NUM> that is distally beyond the opening <NUM> in the cutting blade, and then passes through the opening <NUM> in the cutting blade and through the orifice <NUM> in the shelf <NUM>. The cord then passes beneath the shelf <NUM> proximally beyond the orifice <NUM>, and continues in a proximal direction out through the tool <NUM>. In some preferred embodiments, the saddle <NUM> and any other features in the tool <NUM> and fastener <NUM>/<NUM> that either contact or might potentially contact the cord <NUM> are radiused to reduce the chance of damaging the cord <NUM> before the cord is cut. When the proximal portions of the cord <NUM> are pulled taut, the interaction of those components with the proximal portions of the cord <NUM> will hold the proximal portions of the cord <NUM> at a fixed position with respect to these components <NUM>, <NUM>, and <NUM>. At this stage in the process, the force of the taut cord <NUM> holds the fastener <NUM>/<NUM> in place at the distal end of the tool <NUM> (because shear pins <NUM> and <NUM> have been sheared and no longer perform that function).

Note that before the cord is clipped by the fastener <NUM>/<NUM> (as described above in connection with <FIG>), the proximal portions <NUM> of the cord are threaded through the opening <NUM> of the sliding member <NUM> and flow over the saddle <NUM> (as best seen in <FIG> and <FIG>), through the opening <NUM> in the cutting blade <NUM>, and through the shelf orifice <NUM> while the cutting blade remains in its distal position (as best seen in <FIG>). The geometry of the saddle <NUM> and shelf orifice <NUM> is configured to suspend the cord <NUM> above the blade's slit shaped distal portion <NUM> so that the cord <NUM> does not snag against that slit shaped distal portion <NUM> of the cutting blade <NUM> as the cord <NUM> passes through the opening <NUM> in the cutting blade <NUM> during movement of the tool <NUM> to its distalmost position (as seen in <FIG>) and during constriction of the cord <NUM> (as seen in <FIG>).

Returning to <FIG>, the proximal portions <NUM> of the cord are then cut by pulling the shaft <NUM> in a proximal direction, which pulls the cutting blade <NUM> in a proximal direction. This causes the slit shaped distal portion <NUM> (shown in <FIG> and <FIG>) of the opening <NUM> to be pulled in a proximal direction until it reaches the proximal portions of the cord <NUM>. Because the edges of the slit shaped distal portion <NUM> are sharp, further movement of the cutting blade <NUM> in a proximal direction will cause the slit shaped distal portion <NUM> to cut those portions of the cord <NUM>. Continued pulling on the shaft <NUM> will cause the cutting blade <NUM> to move further in a proximal direction, until it reaches the position depicted in <FIG>. The cutting operation will leave behind two stubs <NUM> of cord. In some preferred embodiments and as best seen in <FIG>, the upper surface of the shelf <NUM> lines up with the upper surface of the housing <NUM> so that the upper surface of the housing <NUM> extends the sliding platform provided by the shelf <NUM>. In these embodiments, the cutting blade <NUM> can slide over both the shelf <NUM> and a portion of the upper surface of the housing <NUM>. Optionally, an aligning feature (e.g., the illustrated notch) may be included at the distal end of the shelf <NUM>, and a corresponding aligning feature (e.g., one or more protrusions) may be provided at the proximal end of the housing <NUM> to improve the alignment between the shelf <NUM> and the housing <NUM>.

<FIG> depict upper and lower detailed views, respectively, of the cutting blade <NUM>. In the illustrated embodiment, the opening <NUM> in the cutting blade <NUM> has a proximal portion that is dimensioned to be sufficiently wide and long to allow both segments of the constricting cord <NUM> to slide freely through the proximal portion, and a slit shaped distal portion <NUM> that is sufficiently sharp and narrow to cut the constricting cord <NUM> when the slit shaped distal portion <NUM> encounters the constricting cord <NUM> and is pulled in a proximal direction against the constricting cord. The slit runs (i.e., is oriented) in a proximal-to-distal direction, and the opening <NUM> tapers down smoothly in a distal direction from the proximal portion towards the slit shaped distal portion <NUM>. In some embodiments, the body of the cutting blade <NUM> is made from <NUM> stainless steel. In alternative embodiments, the body of the cutting blade <NUM> may be made from any of the materials listed above in connection with the housing <NUM>. In some preferred embodiments, the cutting blade <NUM> is <NUM> long (in a proximal-to-distal direction), <NUM> wide, and <NUM> thick; and the proximal portion of the opening <NUM> in the cutting blade <NUM> is <NUM> wide and at least <NUM> long.

<FIG> depict views of the cutting blade <NUM> at two different points in time during one example of a process for manufacturing the cutting blade <NUM>. In this example, a preliminary slit 456p (e.g., with a width of <NUM>-<NUM>) is laser cut into the body of the cutting blade <NUM>, as depicted in <FIG>. Subsequently, the edges of that preliminary slit are swaged towards each other. One way to perform this swaging is to press a fixture with two sharp tips (e.g., fabricated from tools steel) against the surface of the cutting blade <NUM> on either side of the preliminary slit in a direction that is normal to the surface until the edges of the preliminary slit touch each other. When this approach is used, indentations <NUM> are formed on the surface <NUM> of the cutting blade <NUM>, and the width of the slit <NUM> will converge down to zero between the indentations <NUM> as seen in <FIG>, thereby forming a V-notch cutting feature with a sharp cutting edge. When this sharp cutting edge is dragged across the cord <NUM>, it will cut the cord <NUM>. A variety of alternative approaches for forming the slit shaped distal portion <NUM> may also be used.

After the cord <NUM> has been cut (as described above in connection with <FIG>), the tool <NUM> can be withdrawn in a proximal direction, as depicted in <FIG>. After the tool <NUM> has been completely withdrawn, all that will remain in the patient's body is the distal loop portion of the constricting cord <NUM>, the fastener <NUM>/<NUM> (which is holding the distal loop portion of the cord <NUM> securely in a reduced-diameter state), and two small stubs of the constricting cord <NUM>, as seen in <FIG>. Note that because the fastener <NUM>/<NUM> is holding the distal loop portion of the cord <NUM> in a reduced-diameter state and that cord was previously affixed to the annulus, the annulus will also be held securely in a reduced-diameter state.

Claim 1:
An apparatus for reducing a diameter of a cord (<NUM>, <NUM>) that has been previously affixed to an annulus, the apparatus comprising:
a housing having a distal portion and a distal end (<NUM>);
a shelf (<NUM>) positioned in the distal portion of the housing that extends in a distal-to-proximal direction, the shelf (<NUM>) having an upper surface, a lower surface, and a shelf opening (<NUM>) that runs between the upper and lower surfaces of the shelf (<NUM>);
a cutting element (<NUM>) positioned above the shelf (<NUM>) and arranged so that the cutting element (<NUM>) can slide in the distal-to-proximal direction with respect to the shelf (<NUM>), the cutting element (<NUM>) having a flat body with an upper surface, a lower surface, and an opening (<NUM>) that passes between the upper and lower surfaces of the cutting element (<NUM>), the opening (<NUM>) of the cutting element having (a) a proximal portion that is dimensioned so that two segments of the cord (<NUM>) can slide freely through the proximal portion and (b) a slit shaped distal portion (<NUM>) with sharp edges, wherein the slit shaped distal portion (<NUM>) is oriented in the distal-to-proximal direction; and
a fastener (<NUM>/<NUM>) positioned at the distal end of the housing, the fastener (<NUM>/<NUM>) having an opening (<NUM>/<NUM>), wherein the fastener (<NUM>/<NUM>) is movable from a first state in which the cord (<NUM>) is free to slide through the opening (<NUM>/<NUM>) in the fastener (<NUM>/<NUM>) to a second state in which the cord (<NUM>) is locked in place.