Patent Description:
This application describes alternative approaches for cinching the annulus of a cardiac valve, for cinching other types of anatomic passages, and for preventing expansion of an anatomic annulus. To this end, the invention provides an apparatus for cinching an anatomic passage according to claim <NUM>. Further embodiments of the invention are described in the dependent claims. In the cinching embodiments, the cinching cord is incorporated into an implant, and the implant is implanted into the annulus or passage or into adjacent tissue. After the implant with the cinching cord has been implanted, it becomes possible to reduce the diameter of the annulus by cinching the cinching cord. In the closed loop embodiments, the closed loop of cord is incorporated into an implant, and the implant is implanted into an anatomic annulus or into adjacent tissue (e.g., into a cardiac valve annulus or into the leaflets of a cardiac valve near the base of those leaflets).

<FIG> depicts a cinching implant <NUM> that is designed for implantation into an annulus of a cardiac valve such as the mitral valve annulus. The cinching implant <NUM> may be implanted either directly into the annulus itself, or into the leaflets of the cardiac valve near the base of those leaflets. For example, when the implant is installed in the mitral valve, it may be installed directly into the mitral annulus via a catheter from the atrium side or into the leaflets via a catheter from the ventricle side. Note that these two alternative approaches for affixing implants to either the annulus the leaflets are described in application <CIT> (in connection with an implant that has a different construction).

The cinching implant <NUM> includes a cinching cord that has a distal loop portion <NUM>. The distal loop portion has a first and region 33a and a second end region 33b. The first end region is connected to a first proximal portion <NUM> of the cinching cord, and the second end region is connected to a second proximal portion <NUM> of the cinching cord. Most preferably, all three portions <NUM>, <NUM>, <NUM> are formed from a single continuous cord, in which case the connections between the various regions are an inherent property of the single continuous cord. Note that as used herein, the term "cord" includes monofilament cords, multi-filament cords, braided cords, wires, and other cord-shaped flexible structures. Suitable materials for the cinching cord include stainless steel, Dyneema, ultra high molecular weight polyethylene, LCP, Nylon, PET, Dacron, and other high-strength polymers, all of which are biocompatible and sufficiently strong to withstand cinching. The diameter of the cord is preferably between <NUM> and <NUM>. The length of the distal loop portion <NUM> matches the diameter of the annulus to which the implant will be attached. In some embodiments, cinching is implemented from outside the patient's body via a catheter, in which case the first and second proximal portions <NUM>, <NUM> are sufficiently long (e.g., <NUM>-<NUM> each) to reach from the annulus to outside the patient's body via the patient's vasculature.

In alternative embodiments (not shown), instead of forming all three portions <NUM>, <NUM>, <NUM> from a single continuous cord, each of those portions may be implemented using three separate pieces of cord that are joined together (e.g. using welding, clips, knots, bonds, or alternative connecting approaches) so as to form a composite cinching cord.

The <FIG> embodiment is similar to the <FIG> embodiment, but adds an additional component. More specifically, in the <FIG> embodiment, the distal loop portion <NUM> is surrounded by a sleeve <NUM>. (Because it is surrounded by the sleeve <NUM>, the distal loop portion <NUM> is not visible in <FIG>. ) The sleeve <NUM> is made from a material that accepts tissue ingrowth, such as PET braid, Nylon braid, wool, silk, or non-woven polymers. As a result, after the implant <NUM> is implanted into the annulus, tissue that comes into contact with the implant <NUM> will slowly ingrow into the sleeve <NUM>. After the tissue ingrowth process has continued for a sufficient amount of time (e.g., <NUM>-<NUM> months after implantation), the implant will be affixed to the annulus with an extremely strong connection that will be able to withstand cinching. In the embodiment depicted in <FIG>, the sleeve <NUM> is continuous and tubular, and runs the entire length of the distal loop portion <NUM>. In alternative embodiments (not shown), two or more separate pieces of sleeving may be used instead of a continuous sleeve. For example, in a system having N anchors <NUM>, a separate piece of tubular sleeving may be positioned between each of the N anchors <NUM>, in which case N-<NUM> separate pieces of sleeving would be used. In alternative embodiments, non-tubular sleeving may be used.

The distal loop portion <NUM> is also coated with a coating <NUM> that resists tissue ingrowth. The coating <NUM> on the distal loop portion <NUM> prevents the tissue that grows into the implant from adhering to the distal loop portion <NUM>, so that the distal loop portion <NUM> will be able to slide freely within the sleeve <NUM> when cinching is eventually implemented, and prevent the distal loop portion <NUM> from becoming a locked in place by the surrounding tissue due to ingrowth. Suitable materials for the coating <NUM> include Teflon and ePTFE.

In alternative embodiments, the coating <NUM> is omitted, and it is replaced by a lining on the interior surface of the sleeve <NUM> (not shown) that resists tissue ingrowth. This ingrowth-preventing lining helps the distal loop portion <NUM> slide freely within the sleeve <NUM> when cinching is eventually implemented, and helps prevent the distal loop portion <NUM> from becoming locked in place by the surrounding tissue due to tissue ingrowth. Suitable materials for the ingrowth - preventing lining on the interior surface of the sleeve <NUM> include Teflon and ePTFE.

In other alternative embodiments, e.g., when the surface of the distal loop portion <NUM> resists ingrowth sufficiently without help from a coating or lining, both the coating and the lining may be omitted.

The implant <NUM> includes at least four anchors <NUM> and sliding members <NUM> that are distributed around the distal loop portion <NUM> of the cinching cord at positions configured to facilitate implantation of the anchors <NUM> into the annulus (or into leaflets of the cardiac valve adjacent to the annulus) with the first end region of the distal loop portion <NUM> positioned next to the second end region of the distal loop portion <NUM>. Suitable materials for the anchors <NUM> and the sliding members <NUM> include biocompatible metals (e.g., stainless steel) and rigid plastics or composites that are biocompatible. Subsequent to implantation (and preferably after tissue ingrowth occurs), pulling both the first proximal portion <NUM> and the second proximal portion <NUM> in a proximal direction while the first end region is held next to the second end region will reduce the circumference of the annulus into which the implant has been implanted.

The embodiments illustrated in <FIG> and <FIG> each have eight anchors <NUM> and eight corresponding sliding members <NUM>. But in alternative embodiments, a different number of anchors <NUM> may be used. In some preferred embodiments, a larger number of miniature anchors are used. For example, <NUM> anchors that are between <NUM> and <NUM> long may be used. In other alternative embodiments, <NUM> or more anchors are used (e.g., between <NUM> and <NUM>); and in other alternative embodiments, <NUM> or more anchors are used. In the latter case, the anchors may be larger (e.g., between <NUM> and <NUM> long). It is expected that a minimum of four anchors is required to effectively affix the implant <NUM> onto the annulus.

<FIG> is a detail of the anchors <NUM> and sliding members <NUM> that are used in the <FIG> and <FIG> embodiments. Each of the anchors <NUM> has a pointy distal end <NUM> and a proximal end <NUM>, and each of the anchors <NUM> has a slot <NUM> that runs in a proximal-to-distal direction. Each of the anchors <NUM> is configured for implantation into tissue (e.g., the annulus or the base of the leaflets) in a distal direction and is also configured to resist extraction from the tissue in a proximal direction subsequent to implantation. In these embodiments, the pointy distal end <NUM> helps the anchor <NUM> pierce the tissue when the anchor <NUM> is launched into the tissue by an anchor-launcher, and a plurality of barbs <NUM> serve to resist extraction of the anchor <NUM> from the tissue in a proximal direction subsequent to implantation. Although the anchors illustrated in <FIG> have four barbs <NUM>, a different number of barbs (e.g., between one and six) may be used in alternative embodiments.

The implant <NUM> also includes at least four sliding members <NUM>, and each of the sliding members <NUM> is disposed in a slot <NUM> of a respective one of the anchors <NUM>, with a first portion <NUM> of the sliding member <NUM> extending out of the slot <NUM> in a first direction and a second portion <NUM> of the sliding member <NUM> extending out of the slot <NUM> in a second direction. The sliding member <NUM> and the slot <NUM> are configured so that the anchor <NUM> can slide in a distal direction with respect to the sliding member <NUM>. Each of the sliding members <NUM> has at least one protrusion <NUM> on the first portion <NUM> of the sliding member <NUM>, and this protrusion <NUM> is configured to prevent the sliding member <NUM> from passing through the slot <NUM> in the second direction. In the <FIG> embodiment, the protrusion <NUM> is T-shaped, but alternative shapes for the protrusion may also be used.

The second portion <NUM> of each of the sliding members <NUM> has an aperture <NUM>. The first portion <NUM> and second portion <NUM> of the sliding member <NUM> may be formed from a thin sheet of metal, in which case the aperture <NUM> would be a hole through that thin sheet of metal.

Returning now to <FIG> and <FIG>, the distal loop portion <NUM> of the cinching cord passes through the aperture <NUM> in each of the sliding members <NUM>, and each of the apertures <NUM> is configured to retain the distal loop portion <NUM> of the cinching cord within the aperture <NUM>. In addition, in the <FIG> embodiment (which has a continuous sleeve <NUM> disposed over the distal loop portion <NUM>), the sleeve <NUM> also passes through the aperture <NUM> in each of the sliding members <NUM>. In alternative embodiments that use separate sections of sleeve between each anchor, the sleeve would not pass through the aperture <NUM>.

The presence of the distal loop portion <NUM> of the cinching cord in the aperture <NUM> prevents the sliding member <NUM> from passing through the slot <NUM> in the first direction. In the context of the <FIG> and <FIG> embodiment, this means that the presence of the distal loop portion <NUM> of the cinching cord in the aperture <NUM> in each of the sliding members <NUM> prevents the sliding members <NUM> from passing through the slot <NUM> in a radially inward direction (i.e. towards the center of the loop). In addition, the at least one protrusion <NUM> on each of the sliding members <NUM> in this context prevents the respective sliding member <NUM> from passing through the slot <NUM> in a radially outward direction.

Note that in some embodiments, when the size of the aperture <NUM> matches the size of the sleeve <NUM> exactly, no portion of the aperture <NUM> will be able to extend through the slot <NUM> in the anchor <NUM>, which would mean that the aperture <NUM> is limited entirely to the first portion <NUM> of the sliding member <NUM>.

In alternative embodiments, when the size of the aperture <NUM> is larger than the sleeve <NUM>, a portion of the aperture <NUM> may be able to slip through the slot <NUM>, which would mean that the aperture <NUM> extends into the second portion <NUM> of the sliding member <NUM> (i.e., the portion of the sliding member <NUM> on the other slide of the slot <NUM>). This is not problematic because the distal loop portion <NUM> of the cinching cord (and the sleeve <NUM>) will not be able to pass through the slot <NUM> in the first direction, so they will always stay on the side of the aperture <NUM> that corresponds to the first portion <NUM> of the sliding member <NUM>.

In other alternative embodiments (not shown), the sliding member may be formed from a U-shaped member having two arms and a base, and an end of each arm of the U-shaped member is connected to an end cap that protrudes sufficiently to prevent the sliding member from passing through the slot <NUM> in the second direction. In this situation, the aperture would extend all the way from the base of the U-shaped member to the end cap.

<FIG> show the relationship between the anchor <NUM>, the slot <NUM> in the anchor <NUM>, and the sliding member <NUM> at various stages of deployment. Prior to deployment, the body of the anchor <NUM> will be disposed on the proximal side of the cinching cord <NUM> (and the optional sleeve <NUM>), as seen in <FIG>. The sliding member <NUM> passes through the slot <NUM> in the anchor <NUM> at the distal end of the slot <NUM>, and the cinching cord <NUM> passes through the aperture <NUM> of the sliding member <NUM>. Prior to deployment, the cinching implant <NUM> is positioned up against the tissue into which it will be implanted, with the pointy distal ends <NUM> of the anchors facing the tissue.

During deployment, a launcher <NUM> (discussed below in connection with <FIG>) drives the anchor <NUM> in a distal direction. When this occurs, the anchor <NUM> will slide distally with respect to the sliding member <NUM> due to the sliding interface between the anchor <NUM> and the sliding member <NUM> at the slot <NUM>. The pointy distal end <NUM> of the anchor <NUM> will be driven into the tissue and the barbs <NUM> will become embedded into the tissue.

<FIG> shows the relationship between these same components after the anchor <NUM> has been driven distally by the launcher. More specifically, the anchor <NUM> will have moved distally with respect to the sliding member <NUM>, such that the sliding member <NUM> is disposed at the proximal end of the slot <NUM> of the anchor <NUM>. In this position, the pointy distal end <NUM> and the barbs <NUM> of the anchor <NUM> will be disposed on the distal side of the cinching cord <NUM> (and the optional sleeve <NUM>), as seen in <FIG>. Because the cinching implant <NUM> was positioned up against the tissue prior to deployment when the anchors <NUM> were driven into the tissue, the barbs <NUM> of the anchors <NUM> will be embedded in the tissue, which will affix the cinching implant <NUM> to the tissue.

In some preferred embodiments, the portion of the anchor <NUM> on either side of the slot <NUM> has a cylindrical curve, and in some preferred embodiments, the proximal head portion <NUM> of the anchor <NUM> is ring-shaped. In some preferred embodiments, the anchor measures between <NUM> and <NUM> from the distal and of the tip <NUM> to the proximal end of the head portion <NUM>, and the ring shaped head portion <NUM> has a diameter between <NUM> and <NUM>, and the brackets and launcher are sized to fit the dimensions of the anchor <NUM>.

<FIG> show an example of a launcher <NUM> that may be used to drive a respective anchor <NUM> into the tissue, and these figures show the relationship between the launcher <NUM>, the anchor <NUM>, and the bracket <NUM>. More specifically, <FIG> depicts those three components immediately prior to launching of the anchors, and <FIG> depicts those three components immediately after launching of the anchors. Note that each anchor <NUM> of the implant has its own individual launcher <NUM>.

Beginning with <FIG>, the launchers <NUM> includes a launcher body <NUM> with a trigger slot <NUM> located about midway down the launcher body <NUM>, and a distal slot <NUM> located at the distal end of the launcher body <NUM>. The launcher body <NUM> is preferably cylindrical. A compressed spring <NUM> is disposed in the proximal end of the launcher <NUM>, and the anchor <NUM> is disposed in the distal and of the launcher <NUM> immediately beneath the compressed spring <NUM>, so that the distal end of the compressed spring <NUM> pushes on the head portion <NUM> of the anchor <NUM>. (The head portion <NUM> of the anchor is at the proximal end of the anchor <NUM>). A pull wire <NUM> extends down through the center of the compressed spring <NUM>, and the distal and <NUM> of the pull wire <NUM> extends out through the trigger slot <NUM>. In this embodiment, the distal end <NUM> of the pull wire passes below the head portion <NUM> of the anchor just before the distal end <NUM> of the pull wire exits the trigger slot <NUM>. Due to this configuration, as long as the distal end <NUM> of the pull wire sticks out through the trigger slot <NUM>, the pull wire prevents the spring <NUM> from expanding. At this stage, the relationship between the anchor <NUM> and the sliding member <NUM> is at the same as shown in <FIG>.

The launcher <NUM> is triggered by pulling on the pull wire <NUM> in a proximal direction. In some embodiments, the triggering action works best when the pull wire <NUM> is pulled using a quick pulling action (e.g. by jerking the proximal end of the wire rapidly in a proximal direction). An example of a suitable apparatus for implementing this quick pulling action is disclosed in <CIT>.

Pulling on the proximal end of the pull wire <NUM> causes the distal and <NUM> of the pull wire <NUM> to be withdrawn from the trigger slot <NUM>. As soon as this occurs, the spring <NUM> will begin to expand. The proximal end of the spring <NUM> is held in position by the spring retainer <NUM>, so the distal end of the spring <NUM> will move in a distal direction when the spring <NUM> expands. The expanding spring <NUM> will push the proximal head portion <NUM> of the anchor <NUM> in a distal direction, which will drive the anchor <NUM> into the tissue. During this stage of launching, the anchor <NUM> slides with respect to the bracket <NUM> as explained above in connection with <FIG>. The distal end of the anchor will start sliding out of distal end of the launcher body <NUM>. The pointy distal end <NUM> of the anchor <NUM> will pierce the tissue, and the anchor <NUM> will continue moving in a distal direction until the proximal head portion <NUM> of the anchor encounters the sliding member <NUM>. When this happens, the expanding spring <NUM> will begin to push both the anchor <NUM> and the sliding member <NUM> in a distal direction until both the anchor <NUM> and the sliding member <NUM> have been ejected out from the distal end of the launcher body <NUM>, as seen in <FIG>. (Note that the bracket <NUM> remains captive within the slot <NUM>, as explained above in connection with <FIG>. ) At this point, the anchor <NUM> will be embedded in the tissue. The barbs on the anchors <NUM> are configured to prevent the anchors from pulling out of the tissue in a proximal direction.

<FIG> a depicts a catheter-based device <NUM> for delivering the cinching implant <NUM> to the vicinity of the target valve annulus so that it can be implanted into that annulus (or into the base of the leaflets). This device has one launcher <NUM> for each anchor that appears on the cinching implant <NUM>. Each launcher <NUM> is supported by one of the pre-formed arms <NUM>. The cinching implant <NUM> and the pre-formed arms <NUM> are collapsible so that they can be delivered through the shaft <NUM> of the catheter-based device <NUM>, but those components are depicted in <FIG> after having been extended out past the distal end of the catheter. The first proximal portion <NUM> of the cinching cord, and the second proximal portion <NUM> of the cinching cord also run through the shaft <NUM>, as do the pull wires (<NUM>, shown in <FIG>) that are used to trigger the launchers <NUM>. The cinching implant <NUM> is maneuvered into position on the annulus, and the triggers of the launchers <NUM> are actuated.

The interface between the launcher <NUM> and the cinching implant <NUM> is shown in the <FIG> detailed views, which show the interface described above between the sliding member <NUM> and the sleeve <NUM> that surrounds the distal loop portion <NUM> of the cinching cord. More specifically, <FIG> depicts that interface before the launcher <NUM> has been actuated; and <FIG> depicts that interface as the anchor <NUM> is exiting the launcher body <NUM> of the launcher <NUM>. After being launched, the anchors <NUM> will become embedded in the annulus (or into the leaflets), and both the anchors <NUM> and the sliding members <NUM> will be ejected from the launcher body <NUM> (as explained above in connection with <FIG>).

Next, the pre-formed arms <NUM> and the launchers <NUM> are withdrawn back into the shaft <NUM> of the catheter, and the catheter is withdrawn. Only the cinching implant <NUM> and the first and second proximal portions <NUM>, <NUM> of the cinching cord remain behind in the patient's body.

Some preferred embodiments rely on tissue ingrowth to strengthen the bond between the implant and the annulus. In these embodiments, the cinching 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 cinching 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 cinching with a sufficient level of confidence), the cinching cord is cinched so as to reduce the diameter of the annulus.

In other embodiments, the attachment mechanism of the implant may be sufficiently strong to withstand cinching immediately after the implant has been implanted, in which case the cinching cord may be cinched immediately after the implant is implanted.

In some circumstances, the surgeon may not know whether the bond between the implant and the annulus is sufficiently strong to withstand cinching immediately after the implant is implanted. In these circumstances, it could be dangerous to cinch the cinching cord immediately after implantation, because when the bond is not strong enough, the cinching action could tear the implant away from the annulus. In these circumstances, when the implant is designed to accept tissue ingrowth that strengthens the bond between the implant and the annulus, it is preferable to wait until tissue ingrowth strengthens the bond between the implant and the annulus. Here again, after the tissue ingrowth process has strengthened the bond to the point where it will withstand cinching with a sufficient level of confidence, the cinching cord is cinched so as to reduce the diameter of the annulus.

<FIG> shows how cinching of the cinching cord may be implemented by sliding a push-tube <NUM> down over the first proximal portion <NUM> and the second proximal portion <NUM> of the cinching cord until the distal end of the push-tube arrives at the first end region 33a and the second end region 33b of the distal loop portion <NUM> of the cinching cord. (Note that while <FIG> most closely resembles <FIG>, this same process will work for other embodiments described herein, including the <FIG> embodiment. ) Because the first and second proximal portions <NUM>, <NUM> extend through the patient's vasculature between the cinching implant <NUM> and an exit point, those proximal portions <NUM>, <NUM> can serve as a guide wire over which the push-tube <NUM> can be guided to its destination. When the push-tube <NUM> is in this position and is pushed in a distal direction, it will hold the first end region 33a in position next to the second end region 33b, and prevent those two regions from pulling away from each other during the cinching process.

The first and second proximal portions <NUM>, <NUM> of the cinching cord are then pulled in a proximal direction (indicated by arrow <NUM>). Because the distal loop portion <NUM> of the cinching cord is strongly embedded in the annulus, when the first and second proximal portions <NUM>, <NUM> of the cinching cord are pulled in a proximal direction, the cinching cord will cinch the annulus, thereby reducing the circumference of the annulus. The distal ends of the first and second proximal portions <NUM>, <NUM> are then fastened together (e.g. using a knot, fastener, or adhesive) to prevent the annulus from expanding again. The first and second proximal portions <NUM>, <NUM> of the cinching cord can then be clipped at a point that is proximal to the place where they are fastened together.

Note that the <FIG> and <FIG> embodiments are described above in the context of installing a cinching implant on the annulus of a cardiac valve (e.g., the mitral valve) or into leaflets of a cardiac valve near the base of those leaflets, and subsequently cinching that annulus. But the same apparatus can also be used to cinch other anatomic passages or other anatomic annuli (with appropriate modifications for scaling to size as dictated by the relevant anatomy). In these other anatomic contexts, the anchors would be implanted into the anatomic passage or into tissue adjacent to the anatomic passage. After waiting for tissue healing to strengthen the bond between the implant and the tissue, pulling the first proximal portion and the second proximal portion of the cinching cord while holding the first end region and the second end region of the distal loop portion of the cinching cord next to each other (e.g., using a push-tube) will reduce the circumference of the anatomic passage.

<FIG> depict an alternative approach for connecting the anchors to an implant. Instead of using sliding members <NUM> with an aperture <NUM> that encloses the distal loop portion <NUM> of the cinching implant (as in the <FIG> and <FIG> embodiments discussed above) the alternative sliding members <NUM>' in the <FIG> implant are fastened to the sleeve <NUM>', and the anchors <NUM>' slide on those alternative sliding members <NUM>'. A detail of the slidable relationship between the anchors <NUM>' and the alternative sliding members <NUM>' appears in <FIG>. But note that the <FIG> and <FIG> embodiments are superior to the <FIG> implant because the connections between the anchors and the implant will be less stiff in the <FIG> and <FIG> embodiments. (This is due in part to the fact that the connection between each alternative sliding member <NUM>' and the sleeve <NUM>' extends for a significant distance along the circumference of the cinching implant. In contrast, the connection between each sliding member <NUM> and the sleeve <NUM> in the <FIG> and <FIG> embodiments extends for a very short distance along the circumference, and that connection does not have to be a tight connection.

The reduction in stiffness in the <FIG> and <FIG> embodiments makes it easier to reduce the size of the anchors, makes it easier to assemble the implant, improves the collapsibility of the implant when the implant is initially loaded into the catheter for delivery, and also improves the expandability of the implant when the implant exits the catheter. Moreover, the use of smaller anchors makes it possible to increase the number of anchors, which can be beneficial because each individual anchor will not have to be as strong to hold the implant in place, and because the system will still be able to work in the event a small number of anchors (e.g., one or two) are not implanted properly.

Another advantage of the <FIG> and <FIG> embodiments over the <FIG> implant arises from the fact that in the <FIG> implant, the sleeve <NUM>' must be made from a material that is sufficiently strong to retain the sliding member <NUM>' (e.g., PET braid or Nylon braid). This strength requirement limits the selection of materials that can be used. For example, wool would not be a suitable material for the sleeve <NUM>' in the <FIG> implant because the wool might not be strong enough to retain the sliding members <NUM>' without tearing. In contrast, in the <FIG> and <FIG> embodiments, the mechanical strength of the sleeve <NUM> can be much lower. This is because the distal loop portion <NUM> of the cinching cord runs through the aperture <NUM> in the sliding members <NUM>, and because the cinching cord is relatively strong. The <FIG> and <FIG> embodiments can therefore rely on the mechanical strength of those components to hold the implant together, so a strong sleeve is not required.

By removing the mechanical strength properties of the sleeve from the equation, it becomes possible to use a wider variety of materials for the sleeve <NUM>. The material of the sleeve <NUM> can then be better optimized for accepting tissue ingrowth. For example, wool, wool-like, and sponge-like materials that promote tissue ingrowth but have relatively low mechanical strength may be used in the <FIG> and <FIG> embodiments, but would not be suitable for use in the <FIG> implant. The sleeve <NUM> can also have a smaller diameter, and the sleeve <NUM> can be implemented using a plurality of segments (as opposed to requiring a continuous sleeve). Both of these options further contribute in miniaturizing the device.

<FIG> depicts an embodiment of an apparatus for preventing expansion of an anatomic annulus (e.g., a cardiac valve annulus). The anchors <NUM> and sliding members <NUM> in this <FIG> embodiment are similar to the corresponding components in the <FIG> and <FIG> embodiments. But instead of using a cinching cord, the <FIG> embodiment has a closed loop of cord <NUM> that passes through the aperture in each of the sliding members <NUM>. Each of the apertures retains the cord <NUM> within the aperture such that the presence of the cord <NUM> in the aperture prevents the sliding member <NUM> from passing through the slot in the anchors in the first direction (just like the cinching cord in the <FIG> and <FIG> embodiments discussed above). The anchors <NUM> and sliding members <NUM> are distributed around the closed loop of cord <NUM> at positions configured to facilitate implantation of the anchors <NUM> into the anatomic annulus or into tissue adj acent to the anatomic annulus, so that subsequent to implantation, the closed loop of cord <NUM> prevents the anatomic annulus from expanding.

Claim 1:
An apparatus (<NUM>) for cinching an anatomic passage, the anatomic passage having an initial circumference, the apparatus (<NUM>) comprising:
at least four anchoring means (<NUM>) for implanting into tissue and for resisting extraction from the tissue subsequent to implantation, wherein each of the anchoring means (<NUM>) has a slot (<NUM>) that runs in a proximal-to-distal direction;
at least four sliding means (<NUM>) for sliding with respect to the slots (<NUM>) and for remaining captive within the slots (<NUM>), wherein each of the sliding means (<NUM>) has an aperture (<NUM>); and
a cinching means for passing through the apertures (<NUM>) in each of the sliding means (<NUM>), for retaining the sliding means (<NUM>) within the slots (<NUM>), and for cinching the apparatus (<NUM>),
wherein the apertures (<NUM>) retain the cinching means, and
wherein the anchoring means (<NUM>) and the sliding means (<NUM>) are distributed around the cinching means at positions configured to facilitate implantation of the anchoring means (<NUM>) into the anatomic passage or into tissue adjacent to the anatomic passage, so that subsequent to implantation, cinching the cinching means will reduce the circumference of the anatomic passage.