Abstract: One embodiment is directed to a system for closing a wound created across a portion of a tissue structure, comprising a suture member having proximal and distal ends; an anchor member coupled to the distal end of the suture member; a tension retainer assembly releasably coupleable to the suture member; and a suture buttress movably intercoupled to the suture member between the anchor member and the tension retainer and configured to minimize direct sliding contact between the suture member and the tissue structure portion around the location of the suture buttress.

Abstract: Apparatus includes an annuloplasty structure, including: (i) a tubular body portion that is configured to be disposed at an annulus of a valve of a heart, and is shaped to define a perimeter; (ii) a flexible member, disposed within the tubular body portion; (iii) a first adjustment mechanism, attached to the tubular body portion and to the flexible member such that reversible actuation of the first adjustment mechanism reversibly adjusts a first dimension of the body portion by adjusting tension of the flexible member; (iv) a second adjustment mechanism, coupled to the tubular body portion, and reversibly actuatable to reversibly adjust a second dimension of the body portion. The apparatus further includes one or more elongate tools, reversibly couplable to the first and second adjustment mechanisms, and configured to independently actuate the first and second adjustment mechanisms by applying force thereto while the heart is beating.

Abstract: An epicardial clip for reshaping the annulus of the mitral valve of a heart. The epicardial clip includes a curved member having an anterior segment configured to be positioned in the transverse sinus of the heart, a posterior segment configured to be positioned on the posterior side of the heart, such as on or inferior to the atrioventricular groove, and a lateral segment extending between the anterior segment and the posterior segment. The lateral segment includes a curve such that the first end of the member is positioned at or above the plane of the mitral valve and the second end of the member is positioned at or below the plane of the mitral valve.

Abstract: A method and apparatus for securing soft tissue to bone can include forming a bore in the bone and carrying a flexible suture anchor into the bore. The flexible anchor can include a passage and can be coupled to a suture construct. The suture construct can include at least one self-locking adjustable loop, and the flexible anchor can include a first profile while being carried into the bore. A shape of the flexible anchor can be changed from the first profile to a second profile forming an anchoring mass to retain the flexible anchor in the bore. Tension can be applied to a portion of the suture construct to reduce a size of the self-locking adjustable loop and secure the soft tissue relative to the flexible anchor and the bone.

Abstract: The invention is a cardiac implant, and associated methods therefore, configured to repair and/or replace a native heart valve, and having a support frame configured to be reshaped into an expanded/changed form in order to receive and/or support an expandable prosthetic heart valve therein. The implant may be configured to have a generally rigid and/or expansion-resistant configuration when initially implanted to replace/repair a native valve (or other prosthetic heart valve), but to assume a generally non-rigid and/or expanded/expandable form when subjected to an outward force such as that provided by a dilation balloon. The implant may be configured to have a generally D-shaped configuration when initially implanted, but to assume a generally circular form when subjected to an outward force such as that provided by a dilation balloon.

Abstract: Apparatus is provided that includes an annuloplasty system for use on a subject. The system includes an annuloplasty ring, which includes a sleeve having a lumen, and at least one anchor, shaped so as to define a coupling head and a tissue coupling element, which tissue coupling element is shaped so as to define a longitudinal axis, and is configured to penetrate cardiac tissue of the subject in a direction parallel to the longitudinal axis. The system further includes an anchor deployment manipulator, configured to be removably positioned within the lumen of the sleeve, and, while so positioned, to deploy the tissue coupling element from a distal end of the deployment manipulator through a wall of the sleeve into the cardiac tissue in the direction parallel to the longitudinal axis of the tissue coupling element and parallel to a central longitudinal axis through the distal end of the deployment manipulator.

Abstract: Sealable and repositionable implant devices are provided with features that increase the ability of implants such as endovascular grafts and valves to be precisely deployed or re-deployed, with better in situ accommodation to the local anatomy of the targeted recipient anatomic site, and/or with the ability for post-deployment adjustment to accommodate anatomic changes that might compromise the efficacy of the implant. A surgical implant includes an implant body and a selectively adjustable assembly attached to the implant body, the assembly having adjustable elements and being operable to cause a configuration change in a portion of the implant body and, thereby, permit implantation of the implant body within an anatomic orifice to effect a seal therein under normal physiological conditions.

Abstract: A method is provided for treating mitral valve regurgitation, including inserting a band around between 90 and 270 degrees of a mitral valve of a heart, including around at least a portion of a posterior cusp of the valve, in a space defined by (a) a ventricular wall, (b) a ventricular surface of the posterior cusp in a vicinity of an annulus of the valve, and (c) a plurality of chordae tendineae of one or more types of chordae tendineae selected from the group consisting of: second-order chordae tendineae and third-order chordae tendineae. The method also includes applying pressure to the posterior cusp by inflating the band.

Abstract: A method for reducing regurgitation in a mitral valve using a blood flow controlling apparatus. The blood flow controlling apparatus comprises a leaflet coaptation member, a connecting member, and an anchor suitable for anchoring the apparatus to the interventricular septum. The leaflet coaptation member coapts with the native mitral valve leaflets during systole when disposed therebetween, thereby reducing mitral valve regurgitation. During diastole, the native leaflets release coaptation with the leaflet coaptation member, permitting blood flow from the left atrium into the left ventricle.

Abstract: An implantable device is provided for controlling at least one of shape and size of an anatomical structure or lumen. An implantable device has an adjustable member configured to adjust the dimensions of the implantable device. An adjustment tool is configured to actuate the adjustable member and provide for adjustment before, during and after the anatomical structure or lumen resumes near normal to normal physiologic function.

Abstract: Prosthetic mitral valves and their methods of manufacture and use.

Abstract: The present disclosure relates to an arrangement, a loop-shaped support, a prosthetic heart valve and a method of repairing or replacing a native heart valve. With the method or the arrangement, leakage or regurgitation between a prosthetic heart valve and the surrounding valve tissue is prevented. In one embodiment, an arrangement for replacement or repair of a native heart valve is provided, which comprises a loop-shaped support (41) and a prosthetic heart valve (70) and wherein an outer segment (32) of the loop-shaped support (41) is positionable towards surrounding valve tissue of a native heart valve and wherein an outer surface (74) of the prosthetic heart valve (70) is positionable towards an inner segment (34) of the loop-shaped support (41) so as to prevent paravalvular leakage or regurgitation between the prosthetic heart valve (70) and the surrounding valve tissue of the native heart valve.

Abstract: Apparatus is provided that includes an implant structure, which includes a contracting mechanism, which includes a rotatable structure, arranged such that rotation of the rotatable structure contracts the implant structure. A longitudinal member is coupled to the contracting mechanism. A tool for rotating the rotatable structure is configured to be guided along the longitudinal member, to engage the rotatable structure, and to rotate the rotatable structure in response to a rotational force applied to the tool. Other embodiments are also described.

Abstract: In one embodiment of the present invention, a fixation device including a sleeve member including an interior and an exterior surface along a length defined between a first end and a second end, and at least two openings positioned along the length and extending from the interior and through the exterior surface; and a filament including a first free end and a second free end and a length therebetween, the filament positioned relative to the sleeve member such that the free ends extend from the sleeve member at the first and second ends of the sleeve member, the filament being disposed inside the interior from the first end to a first opening, outside the sleeve member from the first opening to a second opening, and inside the interior from the second opening to the second end of the sleeve member.

Abstract: Prosthetic mitral valves and their methods of manufacture and use.

Abstract: The invention includes methods of and apparatus for endovascularly replacing a heart valve of a patient. One aspect of the invention provides a method including the steps of endovascularly delivering a replacement valve and an expandable anchor to a vicinity of the heart valve in an unexpanded configuration; and applying an external non-hydraulically expanding or non-pneumatically expanding actuation force on the anchor to change the shape of the anchor, such as by applying proximally and/or distally directed force on the anchor using a releasable deployment tool to expand and contract the anchor or parts of the anchor. Another aspect of the invention provides an apparatus including a replacement valve; an anchor; and a deployment tool comprising a plurality of anchor actuation elements adapted to apply a non-hydraulically expanding or non-pneumatically expanding actuation force on the anchor to reshape the anchor.

Abstract: The invention is a prosthetic heart valve, and associated methods therefore, configured to replace a native heart valve, and having a support frame configured to be reshaped into an expanded form in order to receive and/or support an expandable prosthetic heart valve therein. The prosthetic heart valve may be configured to have a generally rigid and/or expansion-resistant configuration when initially implanted to replace a native valve (or other prosthetic heart valve), but to assume a generally non-rigid and/or expanded/expandable form when subjected to an outward force such as that provided by a dilation balloon.

Abstract: An apparatus for delivering an implanted structure to a desired target site within a body lumen of a patient includes a catheter having a longitudinally extending catheter lumen and adapted to provide access to the body lumen. A framing member has a collapsed condition in which the framing member is adapted for insertion into the body lumen through the catheter lumen and an expanded condition in which the framing member is adapted for placement within the body lumen. At least one target point is carried by the framing member and is adapted for placement adjacent the desired target site. A holding mechanism is carried by the framing member and is adapted to releasably grasp the implanted structure. At least one target pathway is attached to at least one target point. At least a portion of the target pathway extends through the catheter lumen.

Abstract: Tissue restraining systems and devices as well as methods of using these devices are disclosed herein. According to aspects illustrated herein, there is provided a tissue restraining device that may include a first anchor having one or more contact points along a portion of the first anchor in a spaced relation to one another. The tissue restraining device may also include a second anchor for placement in a substantially opposing relation to the first anchor. A restraining matrix may extend from the contact points of the first anchor to the second anchor.

Abstract: Methods and devices for treating obesity are provided, and more particularly, methods and devices for performing gastric bypasses are disclosed. In one exemplary embodiment a gastric bypass procedure is provided that includes forming a gastro-entero anastomosis between a stomach and an intestine and forming an entero-entero anastomosis between a portion of the intestine distal to the gastro-entero anastomosis and a portion of the intestine proximal to the gastro-entero anastomosis. A surrogate path is formed between the esophagus and the gastro-entero anastomosis to at least partially direct fluid from the esophagus to the intestine by way of the gastro-entero anastomosis, thereby bypassing the stomach. A variety of devices that are particularly useful in gastric bypass procedures are also disclosed. The devices include anastomotic devices that can be coupled to or integrally formed with a shunt. The devices can include a plurality of tubular bodies that are configured to have an adjustable length.

Abstract: An annuloplasty ring is secured around an annulus of a heart valve of a subject by securing an anterior-configured portion of the annuloplasty ring, a posterior-configured portion of the annuloplasty ring, a first commissural portion of the annuloplasty ring, and a second commissural portion of the annuloplasty ring, to respective portion of the annulus. Subsequently, and while the heart is beating, the first commissural portion of the annuloplasty ring is moved inferiorly downwardly with respect to another portion of the annuloplasty ring by rotating a respective first adjusting mechanism of the annuloplasty ring structure, and the second commissural portion of the annuloplasty ring is moved inferiorly downwardly with respect to the other portion of the annuloplasty by rotating a respective second adjusting mechanism of the annuloplasty ring structure. Other embodiments are also described.

Abstract: A method of minimally invasively replacing a cardiac valve of a patient including inserting a delivery catheter intraluminally, inserting a valve resecting instrument intraluminally through the delivery catheter to a position adjacent the cardiac valve of a patient, manipulating the valve resecting instrument to resect the cardiac valve, removing the resected valve through the delivery catheter, and providing a delivery instrument having a replacement valve contained therein. The delivery instrument is advanced into the delivery catheter and intraluminally so that a distal end portion of the instrument is adjacent an annulus of a patient, and a first portion of the valve is exposed from the delivery instrument to position it on a first side of the annulus, and thereafter a second portion of the valve is exposed to position it on a second side of the annulus.

Abstract: A device for improving the function of a heart valve comprises: a support member formed from a shape memory material, and a restraining member providing a restraining action on a course of the support member. The support member may abut one side of the valve conforming to the shape of the valve annulus upon said shape memory material assuming an activated shape while the restraining member restrains the course of the support member. The restraining action is removable for allowing the support member to assume a desired, altered course. The restraining member may be biodegradable to be degraded within a patient or may be detachable from the support member to be withdrawn. The support member according to another embodiment presents a shape change in that an increased cross-section is associated with a shortened length of the support member. The support member according to yet another embodiment has a first and a second activated shape.

Abstract: The invention relates to an implantation device (10a-d) comprising at least one medical implant (12a-d) and at least one implantation aid (14a-d) comprising at least one expansion element (16a-d). It is provided that the expansion element (16a-d) can be inserted into at least one cavity (18a-d) of the implant (12a-d), and the at least one cavity (18a-d) can be expanded using the expansion element (16a-d), and, in the end state, the expansion element (16a-d) is disposed at least partially in the at least one cavity (18a-d), wherein the expansion element (16a-d) is designed as a solid body (20a-d).

Abstract: A device for anchoring a prosthetic heart valve or annuloplasty ring to a valve annulus in a heart and a method of implanting same is disclosed. The device can include a prosthetic valve or annuloplasty ring with one or more anchors configured to be threaded or otherwise passed underneath a native leaflet and/or subvalvular tissue to secure the device at the native annulus.

Abstract: A device for improving the function of a heart valve comprises a first loop-shaped support, which is configured to abut a first side of the heart valve, and a first flange unit being connected to said first loop-shaped support. The flange unit is configured to be arranged against said annulus when said first loop-shaped support is abutting said heart valve.

Abstract: An apparatus (100) for and a method of delivering and implanting a surgical device on an anatomic structure is through minimally invasive procedures. The method is facilitated by an apparatus including a unitary tube (106) operatively connected to a deployment head (118) controlled by an apparatus controller. The deployment head is configured to deploy suture hooks or similar clips that connect an annuloplasty implant to heart tissue and secondary surgical devices to the annuloplasty implant. The apparatus is further configured to facilitate orientation adjustment or collapsing of the deployment head and surgical devices attached thereto in order to facilitate their passing through an incision smaller than generally required. After the deployment head passes through the incision its orientation is readjusted so that it may be positioned and the annuloplasty implant automatically sutured to a heart valve annulus by the apparatus suturing sub-assembly using the suture hooks.

Abstract: A transcatheter valve prosthesis includes an expandable tubular stent, a prosthetic valve within the stent, and an anti-paravalvular leakage component coupled to and encircling the stent which includes a plurality of self-expanding struts and an annular sealing membrane. Each strut has a first end coupled to a distal end of the stent and a second end not coupled to the stent. Each anti-paravalvular leakage component is moveable between a compressed configuration and a deployed configuration. In the compressed configuration, each strut extends distally away from the distal end of the stent. In the deployed configuration, each strut extends proximally away from the distal end of the stent. In an embodiment hereof, the deployed strut has a C-shape and is twisted such that the C-shape lies in a plane substantially along or tangential with the outer surface of the stent. In another embodiment hereof, the deployed strut is rolled-up and extends radially away from the outer surface of the stent.

Abstract: Among other things, a tool to attach a support to a heart valve annulus includes a stabilizing body that includes features to stabilize an axial position of the tool relative to the annulus, and an attachment device connected to the stabilizing body, the stabilizing body and the attachment device being movable relative to one another under control from a location remote from the tool, from one configuration in which the support is held in a pre-attachment contracted state to another configuration in which the support is held in an expanded state for attachment at multiple locations around the annulus by action from the remote location. Among other things, an apparatus includes structural elements, and gripping elements, and configuration elements attached to the respective structural elements and each controllable to permit or prevent the ring from expanding.

Abstract: A method is provided, which includes providing an annuloplasty ring, which comprises (a) a flexible sleeve, and (b) a contracting assembly. During a percutaneous transcatheter procedure, the flexible sleeve is placed entirely around an annulus of a mitral valve of a subject in a closed loop. The sleeve is fastened to the annulus by coupling a plurality of tissue anchors to a posterior portion of the annulus, without coupling any tissue anchors to an anterior portion of the annulus between left and right fibrous trigones of the annulus. Thereafter, a longitudinal portion of the sleeve is contracted. Other embodiments are also described.

Abstract: A method for repairing a mitral valve, the method comprising: positioning a crossing guidewire across the mitral valve, the crossing guidewire passing through the annulus of the mitral valve at a first location and passing through the annulus of the mitral valve at a second location; using the crossing guidewire to position a spanning implant across the mitral valve, with the spanning implant extending from the first location to the second location; anchoring the spanning implant at the first location; tensioning the spanning implant so as to draw the first location and the second location together; and anchoring the spanning implant at the second location.

Abstract: Apparatus and methods are described including an annuloplasty structure configured for implantation along an annulus of an atrioventricular valve of a heart of a subject. The structure includes a coiled element comprising at least one first portion thereof which is flexible and longitudinally compressible, and at least one second portion thereof in series with the first portion, the second portion being flexible and less longitudinally compressible than the first portion. Other applications are also described.

Abstract: An apparatus and method for mitigating prolapsed are disclosed. The apparatus includes a contact member and an elongated rod that can be used to hold the contact member in position for coapting with a patient's native leaflets. A similarly configured sizing apparatus can also be used to facilitate implantation.

Abstract: In one embodiment, the present invention provides a prosthesis that can be implanted within a heart to at least partially block gaps that may be present between the two mitral valve leaflets. In one preferred embodiment, the prosthesis includes an anchoring ring that expands within the left atrium to anchor the prosthesis and a pocket member fixed to the anchoring ring. When the mitral valve is open, blood flows past the pocket member, maintaining the pocket member in a collapsed state. When the mitral valve closes, the backpressure of the blood pushes into the pocket member, expanding the pocket member to an inflated shape. The mitral valve leaflets contact the expanded pocket member, allowing the prosthesis to block at least a portion of the openings between the leaflets, thereby minimizing regurgitated blood flow into the left atrium.

Abstract: A prosthetic anatomical device, such as, for example an annuloplasty prosthesis, is disclosed in which the prosthesis comprises a generally annular core and a cover surrounding the core, with at least a portion of the cover forming a cuff. In some embodiments, the cover may be particularly configured about the core to form the cuff. Various methods and structures for mitigating or retarding movement between the annular core and the fabric cover are also disclosed.

Abstract: A device, a kit and a method are presented for permanently augmenting the pump function of the left heart. The basis for the presented innovation is an augmentation of the physiologically up and down movement of the mitral valve during each heart cycle. By means of catheter technique, minimal surgery, or open heart surgery implants are inserted into the left ventricle, the mitral valve annulus, the left atrium and adjacent tissue in order to augment the natural up and down movement of the mitral valve and thereby increasing the left ventricular diastolic filling and the piston effect of the closed mitral valve when moving towards the apex of the heart in systole and/or away from the apex in diastole.

Abstract: A method for performing an annuloplasty includes positioning an annuloplasty ring structure along an atrial surface of an annulus of a heart valve. While a distal portion of a tube is longitudinally advanced through a channel of the ring structure, it faces a first portion of tissue of the annulus. A first tissue anchor is anchored to the first portion of tissue, from within the channel, while the distal end of the tube faces the first portion of the tissue. After moving the distal portion of the tube to a second portion of the structure, the second portion of the structure is anchored to a second portion of tissue by anchoring a second tissue anchor to the second portion of the tissue while the distal end of the tube faces the second portion of the tissue. Other embodiments are also described.

Abstract: Implants or systems of implants and methods apply a selected force vector or a selected combination of force vectors within or across the left atrium, which allow mitral valve leaflets to better coapt. The implants or systems of implants and methods make possible rapid deployment, facile endovascular delivery, and full intra-atrial retrievability. The implants or systems of implants and methods also make use of strong fluoroscopic landmarks. The implants or systems of implants and methods make use of an adjustable implant and a fixed length implant. The implants or systems of implants and methods may also utilize a bridge stop to secure the implant, and the methods of implantation employ various tools.

Abstract: Described is a set of at least two annuloplasty devices having a particular size that corresponds to an inter-trigonal or inter-commissural distance of a heart valve annulus, wherein the at least two annuloplasty devices have different anterior-posterior ratios. Also, described is a kit for annuloplasty repair of a heart valve annulus including a plurality of annuloplasty devices each comprising one of a plurality of different sizes, wherein the different sizes each correspond to a different inter-trigonal or inter-commissural distance of a heart valve annulus, and for each of the plurality of different sizes there are at least two devices each having the same size but having different anterior-posterior ratios. Additionally, a method of choosing an annuloplasty device for implantation in a valve annulus is described.

Abstract: Apparatus is provided, including a radially-expandable percutaneous implant, a tissue anchor, and a connecting element shaped so as to provide an annular loop surrounding a proximal portion of the tissue anchor in a manner which enables rotation of the anchor about a central longitudinal axis thereof when surrounded by the annular loop. The apparatus also includes a flexible longitudinal member coupled at a first portion thereof to at least a portion of the percutaneous implant and at a second portion to the connecting element. The annular loop of the connecting element facilitates rotation of the tissue anchor about the central longitudinal axis such that the anchor can rotate about the central longitudinal axis with respect to the annular loop, the flexible longitudinal member, and the percutaneous implant. Other applications are also described.

Abstract: Mitral valve prolapse and mitral regurgitation can be treating by implanting in the mitral annulus a transvalvular intraannular band. The band is positioned so that it extends transversely across a coaptive edge formed by the closure of the mitral valve leaflets, to inhibit prolapse into the left atrium. At least one marginal chordae is severed, to permit leaflet closure against the band.

Abstract: Implants or systems of implants apply a selected force vector or a selected combination of force vectors within or across the left atrium, which allow mitral valve leaflets to better coapt. The implants or systems of implants make possible rapid deployment, facile endovascular delivery, and full intra-atrial retrievability. The implants or systems of implants also make use of strong fluoroscopic landmarks.

Abstract: Apparatus and methods are provided for use with a prosthetic valve that is designated for implantation at a patient's native heart valve, including a valve ring having a plurality of ring segments, each of the segments being hingedly coupled to an adjacent segment at a pivot joint. The valve ring is placed adjacent to a surface of the native heart valve, the prosthetic valve having been coupled to the valve ring. In an expanded state thereof, the valve ring defines a ring, all of the pivot joints being disposed in a plane that is perpendicular to a longitudinal axis of the ring. The valve ring is foldable into a shape that has a generally circular cross-section that defines and surrounds at least in part a central lumen, by folding the segments with respect to each other, at the pivot joints. Other embodiments are also described.

Abstract: The disclosure provides systems and related methods for delivering a prosthesis to a target location. Various embodiments of useful valve prostheses are also disclosed.

Abstract: A device for treating mitral regurgitation including an anchor which features one or more reinforcing bars, ribbon and suture.

Abstract: An implantable device for controlling the circumference of internal anatomic passages corrects physiologic dysfunctions resulting from a structural lumen which is either too large or too small. Implants are disclosed which employ various means for adjusting and maintaining the size of an orifice to which they are attached. Systems permit the implants to be implanted using minimally invasive procedures and permit final adjustments to the circumference of the implants after the resumption of normal flow of anatomic fluids in situ. Methods are disclosed for using the implants to treat heart valve abnormalities, gastroesophageal abnormalities, anal incontinence, and the like.

Abstract: Apparatus and methods are described including an implant structure configured to treat a native atrioventricular valve of a patient, the implant structure including a sleeve having a lumen and at least one end, the at least one end being shaped so as to define an opening. A closure element is disposed in a vicinity of the at least one end, the closure element being configured to facilitate closure of the opening. A contracting mechanism is coupled to the implant structure and configured to contract at least a contraction-facilitated portion of the implant structure. Other applications are also described.

Abstract: An implantable device is provided for controlling shape and/or size of an anatomical structure or lumen. The implantable device has an adjustable member configured to adjust the dimensions of the implantable device. The implantable device is housed in a catheter and insertable from a minimally invasive surgical entry. An adjustment tool actuates the adjustable member and provide for adjustment before, during or after the anatomical structure or lumen resumes near normal to normal physiologic function.

Abstract: An annuloplasty ring is secured around an annulus of a heart valve of a subject by securing an anterior-configured portion of the annuloplasty ring, a posterior-configured portion of the annuloplasty ring, a first commissural portion of the annuloplasty ring, and a second commissural portion of the annuloplasty ring, to respective portion of the annulus. Subsequently, and while the heart is beating, the first commissural portion of the annuloplasty ring is moved inferiorly with respect to another portion of the annuloplasty ring by rotating a respective first adjusting mechanism of the annuloplasty ring structure, and the second commissural portion of the annuloplasty ring is moved inferiorly with respect to the other portion of the annuloplasty by rotating a respective second adjusting mechanism of the annuloplasty ring structure. Other embodiments are also described.

Abstract: Apparatus is provided for repairing a valve of a patient, the valve including an annulus and at least first and second leaflets. The apparatus includes at least a first discrete segment and a second discrete segment of an annuloplasty structure, each segment being shaped to provide a respective lateral wall, each lateral wall being shaped to define at least one lumen of the respective segment. The apparatus further includes at least a first and a second control wire, each control wire configured for sliding advancement through both the first and second segments. The first control wire is configured to control a relative disposition of a first end of the first segment and a first end of the second segment. The second control wire is configured to control a relative disposition of a second end of the first segment and a second end of the second segment. Other embodiments are also described.