Patent ID: 12245938

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description refers to the accompanying drawings, which illustrate specific embodiments. Other embodiments having different structures and operation do not depart from the scope of the present disclosure.

Various embodiments of the present disclosure are directed to devices and methods for removing implanted elongated devices from the body. The most common implanted elongated devices include minimally-invasive or percutaneously-delivered catheter systems, though other devices are contemplated. More specifically, the application pertains to devices and methods for coupling extenders to an implanted elongated device to permit advancement of retrieval or removal implements along the implanted device deep into the body.

A particular application of such devices and methods disclosed herein involves removal of an implanted heart valve regurgitation reduction system, which may be implanted within the left or right side of the heart and extends out of the heart into the vasculature, for example, to the subclavian vein. However, the principles disclosed herein that permit removal of such an implanted device are suitable for other applications as well. For example, the presently disclosed devices and methods may be adapted for removing such items as pacemakers or monitors implanted in the heart. Other implanted devices that include an elongated element accessible from close to the surface of the body (e.g., subcutaneously) may also be retrieved using the devices and methods disclosed herein.

FIG.1is a schematic view of the implanted configuration of a percutaneous heart valve regurgitation reduction system having a coapting element positioned within the tricuspid valve and a proximal length of the repair catheter including a locking collet shown exiting the subclavian vein to remain implanted subcutaneously. The system includes a repair catheter20percutaneously delivered into the right side of the heart to reduce tricuspid valve TV regurgitation. The repair catheter20enters the right atrium RA from the superior vena cava SVC after having been introduced to the subclavian vein SV using well-known methods, such as the Seldinger technique. The repair catheter20preferably tracks over a smaller diameter pre-installed anchor rail22that has also been inserted into the subclavian vein SV and steered through the vasculature until it resides and is anchored at or near the apex of the right ventricle RV, as shown. The repair catheter20includes an elongated hollow shaft24that may be reinforced, for example, with an embedded braided or coiled structure.

A distal device anchor26secures a distal end of the rail22at the apex of the right ventricle RV, or to other anatomical features within the ventricle. The anchor rail22may be constructed as a braided wire rod, or cable, and is desirably hollow so as to enable passage over a guide wire (not shown). Further details of the anchor rail22and device anchor26are seen in U.S. Pat. Nos. 8,932,348 and 9,474,605, the entire disclosures of which are expressly incorporated herein by reference.

The repair catheter shaft24carries a spacer or coapting element30on its distal end portion that is ultimately positioned within the tricuspid valve TV, the leaflets of which are shown closed in systole and in contact with the coapting element30. A variety of coapting elements may be utilized, the common feature of which is the goal of providing a plug of sorts within the heart valve leaflets to mitigate or otherwise eliminate regurgitation. In the illustrated embodiment, the coapting element30includes an expandable body that may be adjusted in vivo. Other coapting elements are disclosed in U.S. Pat. Nos. 9,474,605 and 9,636,223, the entire disclosures which are expressly incorporated herein by reference. The coapting element30is delivered in a radially contracted state to reduce the size of the incision used and facilitate passage through the vasculature, and is then expanded within the valve leaflets.

In one preferred embodiment, the coapting element30includes an auxetic structure that expands when subjected to longitudinal tensile force. More particularly, the coapting element30includes a midsection having negative Poisson's ratio properties. Examples of such structures include a laser-cut, pre-compressed anti-tetrachiral pattern such as described below with respect to a connector for the retrieval system.

A locking mechanism is provided on the regurgitation repair catheter20to lock the axial position of the coapting element30within the tricuspid valve TV and relative to the fixed anchor rail22. For example, a locking collet40along the length of the repair catheter shaft24permits the physician to selectively lock the position of the shaft, and thus the connected coapting element30, along the anchor rail22. There are of course a number of ways to lock a catheter over a concentric guide rail, and the application should not be considered limited to the illustrated embodiment. For instance, rather than a locking collet40, a crimpable section such as a stainless steel tube may be included on the repair catheter shaft24at a location near the skin entry point and spaced apart from the location of the coapting element30. The physician need only position the coapting element30within the leaflets, crimp the catheter shaft24onto the anchor rail22, and then sever both the catheter and rail above or proximal to the crimp point.

A proximal length of the repair catheter20including the locking collet40exits the subclavian vein SV through a sealed puncture and remains implanted subcutaneously; preferably coiling upon itself as shown. In the procedure, the physician first ensures proper positioning of the coapting element30within the tricuspid valve TV, locks the repair catheter20with respect to the anchor rail22by actuating the locking collet40, and then severs that portion of the repair catheter shaft24that extends proximally from the locking collet. The collet40and/or coiled portion of the repair catheter shaft24may be sutured or otherwise anchored in place to subcutaneous tissues outside the subclavian vein SV. It is also worth noting that because the repair catheter20initially slides with respect to the anchor rail22, it may be completely removed to withdraw the coapting element30and abort the procedure during implantation. The implant configuration is similar to that practiced when securing a pacemaker with an electrode in the right atrium muscle tissue and the leads extending to the associated pulse generator placed outside the subclavian vein. Indeed, the procedure may be performed in conjunction with the implant of a pacing lead.

Prior to locking the catheter shaft24onto the anchor rail22and severing both, relative linear movement of the two tubes is enabled from their proximal ends. More particularly, these concentric tubes extend a sufficient distance out of the body to be manipulated manually. The length of the inner tube (anchor rail22) is greater than the length of the outer tube (catheter shaft24) so that relative sliding movement is easily accomplished by grabbing or grasping, and displacing the proximal ends with respect to one another, thus providing a sufficient degree of control to implant and conversely retrieve the devices. For instance, the same instrument that delivers the anchor rail22and its device anchor26may be deployed through the catheter shaft24to collapse the anchor, such as to reposition or even retrieve it.

However, once the repair catheter20is locked onto the anchor rail22and severed, it is difficult to manipulate and problematic to achieve or effect removal of either device. That is, relatively short lengths of these components remain to access outside the vasculature, and it becomes difficult to grab and displace them relative to each other. The anchor rail22is embedded into the ventricular tissue with the device anchor26, and the coapting element30is too large in its implanted configuration to be removed through the vasculature—it must first be reduced in size. Unfortunately, inserting elongated removal devices down the system, either within or on the outside of the repair catheter20, is hindered by the short length of the repair catheter shaft24available to grab onto. The present application provides devices and methods for attaching extenders to the concentrically arranged catheter shaft24and anchor rail22so as to permit subsequent advancement of removal devices thereover. In addition to providing added length to the concentric tubes, the extenders are securely coupled to the tubes and permit the application of relative longitudinal force thereto. That is, the connectors and extenders enable independent movement and thus control of the rail22and catheter shaft24.

FIG.1Ashows a percutaneous heart valve regurgitation reduction system similar to that ofFIG.1but without the aforementioned anchor rail22and its distal device anchor26. In this system, the coapting element30is left un-anchored within the tricuspid valve, or secondary anchors (not shown) may be utilized. Since the system only has one main tube, a retrieval system need not have the capacity for grasping concentric tubes, as will be explained below with reference toFIGS.7D and7E.

FIG.2Ais an isolated view of a proximal length of the repair catheter20indicating a preferred severance of a proximal end thereof, andFIG.2Bis an enlarged view of the proximal end of the repair catheter. The first step in retracting the coapting element30and its shaft24involves forming an access opening to the subcutaneous tissue outside of the subclavian vein. The repair catheter shaft24and anchor rail22are then severed distal to the locking structure. Preferably, the catheter shaft24is severed farther down its length than the anchor rail22, such that the anchor rail extends proximally beyond the shaft as shown. For example, the anchor rail22may extend between about 3-10 cm from within and out of the catheter shaft24.

Severing the concentric tubes of the catheter shaft24and anchor rail22in this manner may be done with various tools. For instance, the Accu-Cut Oval Head Hard Wire Cutter from Penn Tool Co. of Maplewood, NJ may be used to cut catheters. Alternatively, various medical tube cutters are available from The Eraser Company of Syracuse, NY, and from Lakeview Equipment of Chicago, IL. Finally, there are a number of manually-operated tube cutters on the market which may be used to sever only an outer tube such as the catheter shaft24concentrically-disposed around an inner tube such as the anchor rail22; for example various tools from Universal Grinding Corporation of Cleveland, Ohio or the Excelta medical tube cutter from Jensen Tools and Supply of North Andover, MA.

FIGS.2C and2Dshow exploded and assembled views of a second step in the procedure involving the coupling of a first or inner rail extension member50to the hollow anchor rail22. The rail extension member50preferably comprises an extension cable which terminates in a tapered tip51. The tapered tip51and extension cable are small enough to fit within the lumen of the anchor rail22, and the user guides the rail extension member50a short distance into the hollow anchor rail22. A hypo tube52, which is laser-welded onto the extension cable50, is then crimped over the anchor rail22. This provides the user with an extended length for the anchor rail22of approximately the same diameter so that it can be displaced or held relative to the repair catheter shaft24, as will be seen. Other solutions for coupling the rail extension member50to the anchor rail22are contemplated and a crimpable hypo tube52should not be considered limiting. For instance, an auxetic anchor, as will be described below, may be utilized.

FIG.3illustrates a full length of the rail extension member50attached to the anchor rail22and a full-length of a shaft anchor60and a second or shaft extension member62that eventually couples to the catheter shaft24, as will be shown. As mentioned, the rail extension member50couples to the anchor rail22via the crimped hypo tube52. The resulting length L1of the combined anchor rail22protruding from the shaft24and its extension50is shown, and is desirably sufficient to enable subsequent advancement of elongated retrieval devices thereof. For example, the length L1may be about 450-600 millimeters. In contrast, a length L2of the shaft anchor60and shaft extension member62is less than the length L1. For instance, the length L2may be about 300-400 millimeters.

In a preferred embodiment, the shaft anchor60is a relatively rigid tubular structure that couples to a relatively flexible tubular shaft extension member62. Co-extensive inner lumens of the shaft anchor60and shaft extension member62are sized slightly larger than the anchor rail22and its extension50, and preferably slightly larger than the crimped hypo tube52therebetween. This permits the combined anchor60and shaft extension member62to slide over the assembly of the anchor rail22and its extension50, as will be explained. Further details of the shaft anchor60will be provided below.

FIG.4Aillustrates an initial step in coupling the outer shaft anchor60and shaft extension member62to the catheter shaft24by passing the shaft extension member over the rail extension member50. As mentioned, the common lumens of the anchor60and extension62are sized to pass easily over the anchor rail22and its extension50. At the same time, a coextensive outer diameter of the assembly of the shaft anchor60and extension62is sized to pass within the lumen of the catheter shaft24.FIG.4Bshows the shaft anchor60extended within the catheter shaft24and coupled thereto, with the shaft extension member62extending proximally therefrom.

FIGS.4C-4Dare enlarged sectional views illustrating constructional details of the shaft anchor60and extension62after insertion and expansion within the catheter shaft24to couple the two elements together. Reference is also made toFIGS.5A-5Eshowing operation of an auxetic expandable section of the shaft anchor60. The shaft anchor60general comprises a rigid tubular body64having a plurality of V-shaped barbs70cut into a distal end thereof. There are preferably two barbs70on diametrically opposite sides of the tubular body64which are cantilevered and taper down in a proximal direction; i.e., they point proximally. The barbs70are formed such as by heat treating to have an outward bias, as indicated inFIGS.5B and5C. The shaft anchor60further includes a central expandable section72and may also include a pair of diametrically-opposed eyeholes74in a proximal end of the tubular body64. The expandable section72comprises an auxetic structure that is configured to radially expand upon being subjected to longitudinal or axial tensile force. A short explanation of auxetic structures is appropriate.

Poisson's ratio expresses the relative nature of a material to contract or expand transversely under axial strain. Most materials contract transversely when subjected to axial strain. This behavior results in a positive Poisson's ratio. The opposite behavior—expanding under axial loading—results in a negative Poisson's ratio. An auxetic (or negative Poisson's ratio) material expands in all directions when pulled in only one, behaving in an opposite way as compared with “classical” materials. Chiral shape-memory-alloy honeycombs have been discussed in the scientific literature for their abilities to exhibit negative Poisson's ratio. The expandable section72of the shaft anchor60has a laser-cut, pre-compressed anti-tetrachiral pattern.

With reference toFIGS.4C-4D, as the shaft anchor60passes into the repair catheter shaft24, the distal barbs70are flexed inward by the smaller lumen size of the shaft. At the same time, compression placed on the shaft60helps to reduce the radial diameter of the expandable midsection72by virtue of its negative Poisson's ratio. Ultimately, the user advances the shaft anchor60at least as far as the expandable midsection72is fully within the catheter shaft24, as shown.

The barbs70point in a proximal direction, and are biased outward to interact with the luminal wall of the repair catheter shaft24, and preferably with a helical stiffening coil76therein, to help prevent proximal movement of the shaft anchor60. That is, the distal barbs70contact and anchor inside of the repair catheter shaft24so as to provide an anchor against proximal movement of the shaft24so as to create tension in the expandable auxetic section72. As explained, the expandable midsection72of the shaft anchor60is formed of an auxetic structure which expands when placed into tension. By pulling on the proximal end of the shaft anchor60while holding the repair catheter shaft24beyond the shaft anchor, the midsection72can be expanded to anchor the shaft anchor60within the repair catheter shaft24. The eyeholes74in the proximal end of the shaft anchor60may be utilized to pass a small linear implement to form a “T” through the tubular body64to help in applying tension to the shaft anchor. Alternatively, a coupling junction76between the shaft anchor60and the shaft extension member62may be robust enough to enable tension to be applied by simply pulling on the shaft extension.

FIGS.5D and5Eillustrate an exemplary laser-cut anti-tetrachiral pattern before and after expansion, respectively. The pattern includes a plurality of evenly-spaced circular rings or hubs77connected to other adjacent hubs by arcuate struts78. In the illustrated embodiment, the pattern features sets of four adjacent circular hubs77forming a square or rectangle around the tubular midsection72each connected by four arcuate struts78. Pulling on the ends of the expandable midsection72tends to straighten the arcuate struts78which generally aligned with the longitudinal axis of the device. Movement arrows are shown on two of these longitudinally-oriented struts78which tend to move away from one another. At the same time, this movement tends to rotate the connected circular hubs77, as shown by the rotational movement arrows. Both the spreading a part of the longitudinally-oriented struts78and the rotation of the circular hubs77tends to straighten out the circumferentially-oriented struts78, as shown.

Of course, other such patterns may be utilized to result in an auxetic structure having a negative Poisson's ratio. It should be understood, therefore, that other expandable structures with negative Poisson's ratio may be used, such as various anti-tetrachiral patterns. Most materials have Poisson's ratio values ranging between 0.0 and 0.5, A perfectly incompressible material deformed elastically at small strains would have a Poisson's ratio of exactly 0.5. Some materials, e.g. some polymer foams, origami folds, and certain cells can exhibit negative Poisson's ratio, and are referred to as auxetic materials. If these auxetic materials are stretched in one direction, they become thicker in the perpendicular direction. In contrast, some anisotropic materials, such as carbon nanotubes, zigzag-based folded sheet materials, and honeycomb auxetic metamaterials to name a few, can exhibit one or more Poisson's ratios above 0.5 in certain directions. For instance, Wu, et al. describes a number of alternative anti-tetrachiral patterns in “Deformation mechanism of innovative3D chiral metamaterials,” SCIENTIFIC REPORTS; 8:12575 (2018), the disclosure of which is hereby expressly incorporated by reference. Likewise, Wu, et al. disclose anti-tetrachiral stent patterns in “Mechanical properties of anti-tetrachiral auxetic stents,” Composite Structures, Volume 185—Feb. 1, 2018), the disclosure of which is hereby expressly incorporated by reference.

FIG.6illustrates the rail extension member50attached to the repair catheter shaft24, with the assembly of the shaft anchor60and shaft extension member62thereover, and a full-length of a removal catheter80that slides over the shaft extension, each in broken line. As described above with respect toFIG.3, the length L1of anchor rail22and its extension is longer than the length L2of shaft anchor60and its extension62. At the same time, the length L2(and also length L1) is longer than the length L3of the removal catheter80, so that when the removal catheter extends over the anchor rail22and catheter shaft24, the shaft extension member62projects proximally therefrom to enable it to be manipulated.

The removal catheter80comprises an elongated sheath82having an inner luminal diameter sized large enough to pass over the assembly of the shaft anchor60and extension62. An elongated device retrieval catheter84passes through a proximal hub86of the removal catheter80and has a length that enables it to extend through and beyond a distal end of the elongated sheath82. As will be described below, a distal end of the retrieval catheter84includes an expandable retrieval cage85, while a proximal end has a hub88with hemostasis valves therein. The inner luminal diameter of the retrieval catheter84including the retrieval cage85is also sized large enough to pass over the assembly of the shaft anchor60and extension62.

FIG.7Aillustrates an initial step in advancing the removal catheter80over the catheter shaft24, whileFIGS.7B and7Cshow the removal catheter80advanced into the subclavian vein and initial retraction of the catheter shaft24and the coapting element30thereon from within the tricuspid valve. The removable catheter sheath82with the retrieval catheter84therein is first advanced over the proximal end of the anchor rail extension member50, and then over the proximal portion of the shaft extension member62, as seen inFIG.6. The user advances the catheter sheath82until its distal end slides over the catheter shaft24. The distal tip of the catheter sheath82may be slightly tapered to facilitate entry through the puncture wound into the subclavian vein SV.

With reference toFIG.7B, the removal catheter sheath82advances over the catheter shaft24and along a predetermined distance of the subclavian vein SV and halts approximately at the beginning of the superior vena cava SVC, as shown inFIG.7C.

FIG.7Calso illustrates proximal retraction of the repair catheter shaft24toward the removal sheath82such that the coapting element30eventually comes into proximity with the distal end of the removal sheath. During this process, the rail extension member50is held stationary to counteract any tension applied to the anchor rail22and its anchor26. Additionally, the strong anchor formed by the coupling of the shaft anchor60within the repair catheter shaft24is important to prevent decoupling. Tension exerted on the proximal end of the shaft extension member62helps to increase the anchoring force by expanding the midsection72of the shaft anchor60, as was described above with respect toFIG.4D.

FIGS.7D and7Eshow an alternative to the just-described embodiment, and specifically the system inFIG.1Awith a removal catheter82advanced into the subclavian vein and initial retraction of the catheter shaft24and the coapting element30thereon from within the tricuspid valve. In the alternative embodiment, the percutaneous heart valve regurgitation reduction system has no anchor rail, and thus the retrieval system need only grasp onto one tube, as opposed to concentric tubes. The steps shown inFIGS.3-4are followed to attach the shaft extension member62to the catheter shaft24via the expandable anchor60. As mentioned, a coextensive outer diameter of the assembly of the shaft anchor60and extension62is sized to pass within the lumen of the catheter shaft24.FIG.4Bshows the shaft anchor60radially outwardly extended within the catheter shaft24and coupled thereto, with the shaft extension member62extending proximally therefrom. The alternative system has no need for the anchor rail extension50as there is no anchor rail22. Otherwise, the two systems are alike, with the shaft anchor60taking an of the forms as described herein.

Subsequently, the removal catheter80is advanced over the catheter shaft24. The removal catheter80may be as described above and comprise the elongated sheath82having an inner luminal diameter sized large enough to pass over the assembly of the shaft anchor60and extension62. An elongated device retrieval catheter84passes through the proximal hub86of the removal catheter80and has a length that enables it to extend through and beyond a distal end of the elongated sheath82. A distal end of the retrieval catheter84again includes the expandable retrieval cage85, while a proximal end has the hub88with hemostasis valves therein. The inner luminal diameter of the retrieval catheter84including the retrieval cage85is also sized large enough to pass over the assembly of the shaft anchor60and extension62.

With reference toFIG.7D, the removal catheter sheath82advances over the catheter shaft24and along a predetermined distance of the subclavian vein SV and halts approximately at the beginning of the superior vena cava SVC, as shown inFIG.7E.FIG.7Dillustrates proximal retraction of the repair catheter shaft24toward the removal sheath82such that the coapting element30eventually comes into proximity with the distal end of the removal sheath. During this process, the strong anchor formed by the coupling of the shaft anchor60within the repair catheter shaft24is important to prevent decoupling. Tension exerted on the proximal end of the shaft extension member62helps to increase the anchoring force by expanding the midsection72of the shaft anchor60, as was described above with respect toFIG.4D.

The alternative embodiment ofFIGS.1A and7D/7E represents any number of retrieval systems that may be used to couple to a singular tube within the body for retrieval thereof. That is, the shaft anchor60and extension62that pass within the lumen of the catheter shaft24may be utilized to couple to any tubular implant or instrument within the body that requires removal, or simply an extension therefor.

FIGS.8A-8Dare enlarged views of a distal end of the removal sheath82showing several steps in utilizing the retrieval cage85to draw the coapting element30into the removal sheath82. First of all, the retrieval catheter84is advanced such that the retrieval cage85projects distally from the distal end of the removal sheath82. The retrieval cage85is elastic in nature and expands to a larger diameter than the coapting element30, and has an open distal end. By then proximally retracting the repair catheter shaft24via the shaft extension member62, the coapting element30may be pulled within the retrieval cage85, as inFIG.8B. Subsequent retraction of the retrieval cage85, as indicated inFIG.8C, causes it to be pulled into the narrower removal sheath82, simultaneously constricting the coapting element30and pulling it along into the removal sheath. Finally, the repair catheter shaft24and its extension62are fully removed from within the removal sheath82, as inFIG.8D.

FIGS.9A and9Bshow advancement of a rail removal device100through the removal sheath82and subsequent removal of the anchor rail22from its embedded position within the right ventricle.FIG.9Ashows advancement of the rail removal device100through the removal sheath into proximity with the rail anchor26. The rail removal device100may be the delivery system that originally implanted the rail22and its anchor26. The rail removal device100is advanced until it surrounds an anchor hub, just proximal to the anchor26, at which point the rail22may be pulled proximally via the rail extension member50to retract the prongs of the anchor26into the removal device. The entire system can then be retracted through the sheath from the body, as seen inFIG.9B.

At this stage, another valve repair system may be inserted through the removal sheath82, or through a different access tube, to position a different coapting element within the tricuspid annulus.

While the foregoing is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Moreover, it will be obvious that certain other modifications may be practiced within the scope of the appended claims.