PRIORITY CLAIM This application claims the benefit of U.S. Provisional Patent Application having Ser. No. 60/720,398 filed on Sep. 26, 2005, entitled “Prosthetic Cardiac Valves”, the entire disclosure of which is incorporated herein by reference for all purposes.
TECHNICAL FIELD The present invention relates to prosthetic heart and venous valves used in the treatment of cardiac and venous valve disease. More particularly, it relates to minimally invasive and percutaneous replacement of cardiac and venous valves.
BACKGROUND Recently, there has been a substantial level of interest in minimally invasive and percutaneous replacement of cardiac valves. In the specific context of pulmonary valve replacement, U.S. patent application Publication Nos. 2003/0199971 A1 and 2003/0199963 A1, (Tower et al.), which are incorporated herein by reference in their entireties, describe a valved segment of bovine jugular vein mounted within an expandable stent, for use as a replacement pulmonary valve. The replacement valve is mounted on a balloon catheter and delivered percutaneously via the vascular system to the location of the failed pulmonary valve and expanded by the balloon to compress the valve leaflets against the right ventricular outflow tract, anchoring and sealing the replacement valve. The valve is also useful to replace failed pulmonary valves located in valved conduits.
U.S. Pat. No. 5,411,552 (Andersen et al.) discloses a percutaneously deliverable valve for aortic valve replacement. Like the Tower et al. valve, this valve system employs a stent external to the valve to exert pressure against the vessel at the implant site to provide a seal. This pressure of the stent against the vessel also helps to keep the valve from becoming displaced once it has been implanted. With these and other percutaneously delivered valves, the stent or other expandable member is typically designed to surround at least the valve orifice. This basic configuration allows blood to flow through the center of the valve when the valve is open, with the multiple valve leaflets sealing against themselves to close the valve. Because the native aortic valve annulus in which the replacement is to be implanted may be calcified and have an irregular perimeter, this basic configuration can be problematic, particularly in the context of replacement aortic valves. For example, a valve annulus with an irregular perimeter can make it difficult for an expanded stent to accurately follow the contours of the native annulus, which can result in peripheral fluid leakage. This problem is typically not present in traditional surgically implanted valves, since their relatively rigid stents are typically sealed to the valve annulus with a sealing ring that is attached to the annulus by means of numerous sutures.
Other procedures and devices that have been developed include, for example, surgically implantable valves disclosed in U.S. Pat. Nos. 4,339,831 (Johnson) and 5,449,384 (Johnson), both of which are incorporated herein in their entireties. These valves have a configuration that is essentially the opposite of the natural configuration, such that the valve leaflets open inwardly and close by expanding outwardly to contact the native aortic valve annulus. These valves further include a framework comprising a plurality of struts that are sutured to the patient's annulus or an artificial annulus reconstruction ring and a flexible membrane attached to the framework to allow the membrane segments or leaflets to freely open inward to allow forward blood flow through the valve. Although the struts are described as being flexible, these valves are not contemplated to be implanted percutaneously due to the need to physically suture these implantable valves to the annulus of a patient. Another type of valve that was developed is described in U.S. Pat. No. 3,671,979 (Moulopoulos). This reference discloses a valve that can be inserted, withdrawn and retained relative to its desired implanted position with the use of a catheter. A membrane of the valve expands outward like an umbrella to seal against the interior of the aorta, downstream of a damaged aortic valve, and collapses and enfolds the catheter to allow flow of blood when the valve is open. However, this valve is not capable of being retained in this position and functioning as a valve without the use of its catheter.
There is a continued desire to provide cardiac valves that can be implanted in a minimally invasive and percutaneous manner, while minimizing or eliminating paravalvular leakage.
SUMMARY The present invention is particularly directed to improvements in minimally invasive and percutaneously delivered valves for use in pulmonary and aortic positions. However, the invention may also be useful in other types of valves, including other heart valves and peripheral venous valves. In particular, a valve of the invention has leaflets that are configured to operate in an essentially an opposite manner from a typical artificial valve. Using this reverse or opposite configuration in a minimally invasively or percutaneously delivered valve with a collapsible stent can provide certain benefits. In particular, the outwardly sealing valve leaflets may adapt themselves or conform more readily to irregular configurations of the orifice in which the valve is mounted, thereby overcoming or reducing the sealing problems sometimes associated with expandable stents that are external to the valve leaflets.
The present invention also includes embodiments of a variety of outwardly sealing multi-leaflet valves, which are believed to be especially useful in conjunction with a number of different embodiments of collapsible stents.
In some embodiments of the invention, the valve leaflets are produced by inverting a section of a naturally valved vessel, such as a porcine aorta or a bovine jugular vein. In other embodiments, the valve leaflets are produced by sealing one end of a flexible tube and employing the unsealed end to define the leaflets. In yet other embodiments, the valve is produced by stitching together leaflets of flexible material such as pericardial tissue to provide a generally cup shaped structure. With any of these described embodiments, the valve leaflets are mounted to an expandable stent which is to be anchored to the orifice in which the valve is implanted. This valve implantation is positioned to be downstream of or adjacent to the free edges of the leaflets.
In some embodiments of the invention, the expandable stent may be configured with a flexible frame that is manufactured of a material consistent with being collapsed to allow delivery through a tubular percutaneous catheter or minimally invasive tubular surgical port type device. In other embodiments, the stent may include a self-expanding or balloon expandable circumferential stent that is located downstream of the free edges of the valve leaflets. In still other embodiments the stent may include outwardly extending barbs that are preferably, but not necessarily, located downstream of the free edges of the leaflets.
In one embodiment of the invention, a prosthetic heart or venous valve is provided, the valve comprising a central tissue structure comprising multiple tissue lobes extending from a common central area, wherein each of the lobes includes a longitudinal slot. The valve further comprises a plurality of leaflets extending from the central tissue structure and positioned between two adjacent lobes, wherein each of the leaflets comprises a free end spaced from the central tissue structure, and also comprises a compressible and expandable stent frame comprising a plurality of extending arms, wherein each of the extending arms of the stent frame is positioned at least partially within one of the longitudinal slots of the central tissue structure. The central tissue structure can comprise a native valve segment that has been inverted to provide the plurality of leaflets, wherein the multiple tissue lobes can be formed by folded portions of an aortic wall of the native valve segment.
In another aspect of the invention, a prosthetic valve is provided, which comprises a flexible tube having an inflow end and a outflow end, wherein the inflow end of the tube is folded against and attached to itself and the outflow end of the tube is unattached to itself, and a stent having multiple longitudinally extending members located at least partially within the tube and extending to the open outflow end of the tube, wherein portions of the tube that are adjacent the outflow end of the tube and between the longitudinally extending members of the stent are moveable toward and away from a central area of the valve to provide a plurality of valve leaflets.
BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:
FIG. 1 is a top view of a natural aortic valve;
FIG. 2 is a top view of the natural aortic valve of FIG. 1 with the valve structure turned “inside-out” on itself such that the leaflets are positioned on the outside of the valve in a tri-lobed configuration;
FIG. 3 is a side view of the natural aortic valve turned “inside-out” as in FIG. 2, with the aortic wall sutured to itself at an inflow end of the valve;
FIG. 4 is a side view of the natural aortic valve turned “inside-out” as in FIG. 2, with the aortic wall sutured to itself at an inflow end of the valve, wherein the aortic wall is trimmed to more closely match the configuration of typical valve leaflets;
FIG. 5 is a side view of one embodiment of a stent for use in conjunction with valves of the type illustrated in FIGS. 3 and 4;
FIG. 6 is a side view of the stent of FIG. 5 mounted inside a valve of the type illustrated in FIG. 4 to provide one embodiment of a completed replacement valve of the invention;
FIG. 7 is a side view of the replacement valve of FIG. 6, as positioned within an aortic annulus, which is illustrated in cross-section;
FIG. 8 is a side view of a delivery catheter or device positioned within an aortic annulus, with the replacement valve of FIG. 6 partially advanced from one end of the catheter or device;
FIG. 9 is a side view of the delivery catheter or device illustrated in FIG. 8, with the replacement valve of FIG. 6 being further advanced from one end of the catheter into the aortic annulus;
FIG. 10 is a side view of the replacement valve of FIG. 6 in a desired position within an aortic annulus, which is also the position it will generally be in after it has been completely advanced from the end of the delivery device of FIGS. 8 and 9;
FIG. 11 is a side view of a delivery catheter within an aortic annulus that includes a balloon catheter that is radially expandable to anchor a replacement valve into the tissue of a patient;
FIG. 12 is a side view of an alternative embodiment of a replacement valve of the type illustrated in FIG. 6 as positioned within an aortic annulus, which includes an alternative embodiment for anchoring the valve;
FIG. 13 is a side view of another alternative embodiment of a replacement valve of the type illustrated in FIG. 6 as positioned within an aortic annulus, which includes another alternative embodiment for anchoring the valve;
FIG. 14 is a top view of a replacement valve generally of the type illustrated in FIG. 6, which further includes optional tissue or fabric portions to prevent leakage adjacent the valve commissures;
FIG. 15 is a side view of an alternative structure to provide valve leaflets that are mounted to a stent to provide an alternative embodiment of a completed replacement valve of the invention;
FIG. 16 is a side view of the alternative valve leaflet structure of FIG. 15, which uses an alternative stent configuration;
FIG. 17 is a side view of a flexible tube of natural or synthetic material as can be used for replacement valves of the invention;
FIG. 18 is a perspective view of a replacement valve fabricated from the tube of FIG. 17 and mounted to a stent, which includes having its inflow end sutured to produce a tri-lobed structure;
FIG. 19 is a top view of the replacement valve of FIG. 18, as located within the aortic annulus;
FIG. 20 is a top view of an alternative structure of the replacement valve of FIG. 18;
FIG. 21 is at top view of another alternative structure of the replacement valve of FIG. 18;
FIG. 22 is an enlarged top view of a portion of the replacement valve of FIG. 21;
FIG. 23 is a perspective view of a replacement valve fabricated from the tube of the type illustrated in FIG. 17 and mounted to a stent, which includes having its inflow end sutured to create a bi-lobed structure;
FIG. 24 is an enlarged top view of a portion of the replacement valve of FIG. 23;
FIG. 25 is a perspective view of an alternative embodiment of the replacement valve of FIG. 23, which is folded onto itself to provide for passage through a catheter;
FIG. 26 is a perspective view of an alternative stent configuration for use with the leaflets configured in accordance with the present invention;
FIG. 27 is a top view of another embodiment of a replacement valve having a bi-lobed structure; and
FIG. 28 is a top view of another embodiment of a replacement valve having a bi-lobed structure.
DETAILED DESCRIPTION Referring now to the Figures, wherein the components are labeled with like numerals throughout the several Figures, and initially to FIG. 1, a natural aortic valve 3 is illustrated, which generally comprises three leaflets 2 extending from an aortic wall 4. The leaflets 2 meet at their free edges 6 to seal the valve orifice when the valve 3 is in its closed position. The free edges 6 can move away from each other and toward the aortic wall 4, however, when the valve 3 is in its open configuration, thereby creating an open passage for blood flow. Such a natural aortic valve 3 may be a valved segment of a porcine valve, for example, which can be particularly advantageous in certain aspects of the invention due to the relatively thin aortic walls of these valves.
FIG. 2 illustrates an top view of an aortic valve 16, which is basically the valve 3 of FIG. 1 turned “inside-out” as compared to its natural state. That is, the aortic wall 4 is folded or rolled inwardly so that the side of the wall 4 that was previously facing in an outward direction is on the inside of the valve 16. The aortic wall 4 is further configured so that it defines a tri-lobed configuration, with the leaflets 2 on the outside of the valve 16 rather than the inside of the valve, as will be described in further detail below. In this configuration, the free edges 6 of leaflets 2 are located at the external periphery of the valve 16 such that the free edges 6 no longer will be in contact with each other when the valve 16 is in its closed configuration, but instead will be in contact with the vessel in which it is implanted (e.g., aorta). In fact, the leaflets 2 are facing in a generally opposite direction from the direction they are facing in a valve in its natural state.
In the embodiment of FIG. 2, the aortic wall 4 further defines three internal longitudinally extending slots 8 in the area where the wall 4 is folded onto or toward itself. That is, each of the lobes of the tri-lobed configuration includes a slot 8 extending through it. Because the valve 16 opens inwardly, rather than outwardly, relative to the structure in which it is positioned (e.g., an aorta), the leaflets 2 will seal against the aorta or other structure in which the valve is positioned when the valve 16 is in a closed state and will move toward the inner, tri-lobed structure when the valve 16 is in an open state. Thus, paravalvular leakage can be minimized or eliminated as compared to valves in which the radial strength of a stent is an issue.
In order to allow the free edges 6 of leaflets 2 of FIG. 2 to better conform to the tissue annulus in which the valve 16 is positioned, it is desirable for the leaflets 2 to have a certain level of elasticity. This can be accomplished by fixing the valve material with glutaraldehyde, for example, using conventional high, low or zero pressure fixation techniques, although other fixing techniques and materials can be used. In some embodiments, the aortic wall 4 may be trimmed to reduce the thickness of the wall, which will provide different properties for the valve (e.g., strength, flexibility, and the like). In addition to the porcine valve material discussed above, such a valve structure can be produced, for example, starting with a valved segment of bovine jugular vein that is trimmed to make its walls thinner and thus more adaptable to at least some of the valve configurations of the invention.
FIG. 3 illustrates a side view of the valve 16 of FIG. 2, with adjacent portions of an inflow end 12 of the folded aortic wall 4 attached to each other by sutures 10 to seal the end of the valve 16 and maintain the tri-lobed structure. Alternatively, adhesive or other surgical fasteners can be used to secure the inflow end 12 of the structure in such a configuration. In either case, in order to pull the sections of the wall 4 closer to each other along the slots 8, a vacuum can be pulled on the valve 16 prior to using the sutures or other material to seal the end of the valve 16. FIG. 4 illustrates an alternative embodiment of the aortic valve of FIG. 3, with the inflow end 12 of the aortic wall 4 being trimmed into a curved shape to more closely match the configuration of the bases of the valve leaflets 2 and to eliminate excess valve material extending beyond the leaflets 2.
Referring now to FIG. 5, one embodiment of a stent 18 is shown, which can be used in conjunction with valves of the type illustrated in FIGS. 3 and 4. The stent 18 includes three longitudinally extending curved arms 20 that extend from a common point 22, which will be positioned adjacent to the inflow end of a replacement valve. The arms 20 are shown as being generally the same length as each other in this figure, which will be adaptable to the implantation location of most replacement valves. It is possible, however, that at least one of the arms 20 is a different length than the other arms 20, such as in cases where particular anatomical needs of a patient need to be accommodated, when certain anchoring techniques are used, or when other considerations of the patient, the valve, or the delivery systems need to be considered, for example. The three arms 20 can be angularly displaced approximately 120 degrees from one another so that they are evenly spaced around the perimeter of the stent 18; however, it may instead be desirable to position the arms 20 at different angular spacings from each other.
In one embodiment of the invention, one or more of the arms 20 further include outwardly extending barbs or connectors 24 at an outflow end 14 of the stent 18. These connectors 24 are designed to engage with the wall of the aorta or other tissue structure in which the stent 18 may be positioned. Connectors 24 can include a wide variety of configurations and features, such as the arrow-shaped tips shown, or other configurations that provide for engagement with tissue through a piercing or other similar motion, and further do not allow the connector to disengage from the tissue with normal movement of the stent within the tissue. Each of the arms 20 of this embodiment are shown as including two barb-like connectors 24; however, more or less than two connectors 24 may extend from a single arm 20, and each of the arms 20 of a stent 18 may include the same or a different number of connectors 24.
The stent 18 is constructed of a material that is sufficiently flexible that it can be collapsed for percutaneous insertion into a patient. The material is also preferably self-expanding (e.g., Nitinol) such that it can be readily compressed and re-expanded. The material should further be chosen so that when the stent 18 is positioned within an aorta, for example, it exerts sufficient pressure against the aortic walls that fluids cannot leak past the stent 18. In particular, the stent 18 should provide enough radial outward force so that the tips or ends of the fold material of a tri-lobed structure can press against the inside walls of an aorta or other structure of a patient in such a way that blood cannot flow past these tips of the replacement valve. In this and any of the embodiments of the invention, the replacement valves and associated stents can be provided in a variety of sizes to accommodate the size requirements of different patients.
FIG. 6 illustrates the stent 18 of FIG. 5 mounted inside a valve 16 of the type illustrated in FIG. 4 to provide a completed replacement valve 26. As shown, the ends of the arms 20 extend beyond the ends of the valve 16 at the outflow end 14 of the valve; therefore, an area of the stent 18 relatively near the common point 22 (not visible in this figure) is positioned adjacent to the inflow end 12 of the valve 26. The adjacent tissue portions of the lobes at both the inflow end 12 and the outflow end 14 of the replacement valve 26 can be sewed or otherwise connected to each other, such as by sutures 10, in order to prevent or minimize the possibility of blood entering the slots 8 (see FIG. 2) of the tri-lobed structure.
The stent 18 is preferably retained in position within the slots 8 of aortic wall 4 by means of adhesive, sutures or other surgical fasteners. In one exemplary construction, the stent 18 is positioned within the slots 8 before the tissue is sutured or attached to itself at one or both of the inflow and outflow ends 12, 14. When the tissue at the inflow end 12 is sutured, the adjacent stent 18 can be sutured to the valve 26 at the same time, such that one stitching operation can serve the dual purpose of sealing the inflow end 12 of the valve 26 and also securing the stent 18 to the valve 26.
Referring now to FIG. 7, a replacement valve of the type generally shown as the valve 26 in FIG. 6 is illustrated, as mounted in an aortic annulus 28 of a patient. The valve 26 is positioned so that the free edges 6 of the leaflets 2 contact the annulus 28 around at least a substantial portion of the circumference of the aortic annulus 28, and preferably contact the annulus 28 around its entire circumference. The valve 26 is further positioned along the length of the aorta so that the connectors 24 are above the sinuses of Valsalva 32 and adjacent to a wall 30 of the patient's aorta. The connectors 24 are shown here as being slightly spaced from the wall 30, such as when the valve 26 is in an at least slightly compressed or unexpanded state. However, the arms 20 will be move or be forced to move at least slightly outward toward the walls 30 until the connectors 24 are imbedded or engaged with at least a portion of the thickness of the walls 30. These connectors 24 will then serve the purpose of retaining the valve 26 in its desired implant location relative to the aorta. In one embodiment, the connectors 24 can be designed to extend through the entire thickness of the walls 30 such that they will basically be anchored to the outside surface of the aortic walls 30. Alternatively, the connectors may be designed to extend only through a portion of the thickness of the walls 30, which, in order to keep the valve 26 securely in place, may require a different style of connector than a connector that extends entirely through an aortic wall. That is, connectors that need to engage within the thickness of a tissue can include a number of barbs or tissue engaging structures on each connector, while a connector that extends all the way through the tissue may only need to have a relatively wide base that will not easily pass backward through the hole it created when originally passing through the tissue.
In order to prevent possible interference between the patient's native valve and a replacement valve of the type illustrated in FIG. 6, for example, the native valve can be completely or partially removed. In some cases, the native valve may be left in its original location; however, the replacement valve in such a circumstance should be positioned in such a way that the remaining native valve does not interfere with its operation. In cases where the native valve is to be removed, exemplary valve removal or resection devices that can be used are described, for example, in PCT Publication WO/0308809A2, which is incorporated herein by reference in its entirety.
FIGS. 8-10 illustrate an end portion of one exemplary delivery device and exemplary sequential steps for using such a device for delivering a replacement valve 26 to its desired location within a patient. In particular, FIG. 8 illustrates a tubular delivery device 34 that has been advanced to the general location where the replacement valve 26 will be implanted. In order to reach this location, the delivery device 34 is inserted into the body using one of a number of different approaches. For example, the device 34 can reach the aorta through a retrograde approach originating at a location distal to the heart, such as the femoral artery. Alternatively, an antegrade approach could be used, which originates at a location distal to the heart, such as the femoral vein or an incision in the ventrical wall or apex. In any case, the device 34 is moved to the desired implantation area of the body with a replacement valve 26 being partially or entirely enclosed within an outer sheath 35. As shown in the figure, the portion of sheath 35 at the distal end of device 34 is at least slightly larger in diameter than the adjacent portion of the device 34, which will help to keep the valve 26 positioned near the distal end of device 34 (i.e., keep it from translating along the length of the device 34). However, the distal end of the sheath 35 may additionally or alternatively include a stop or some other configuration that keeps the valve 26 from migrating away from the distal end of device 34.
With particular reference to FIG. 8, the replacement valve 26 is shown as it is beginning to be advanced out of the end of a tubular delivery device 34 by pulling back the sheath 35, thereby releasing or exposing one end of the replacement valve 26. In accordance with the invention, the valve 26 is delivered in a radially compressed configuration to ease passage of the device 34 through the vascular system; however, the valve 26 will be able to expand after it is released from the end of the device 34. The leaflets 2 of the valve 26 are first are advanced distally out of the end of the device 34, as illustrated in FIG. 8, so that they can be properly located relative to the aortic annulus 28. FIG. 9 illustrates the replacement valve 26 as it is further released from the device 34 by further retraction of the sheath 35. As the delivery device 34 is withdrawn, the stent 18 of the valve 26 is allowed to expand and seat the replacement valve 26 in its desired location.
Finally, FIG. 10 illustrates the stent of the replacement valve 26 after the delivery device 34 has been retracted a sufficient amount that it is completely separated from the valve 26. In this embodiment, the arms 20 are configured so that they tend to expand radially outwardly once they are released from the sheath 35. The outward radial force causes the barbs or connectors 24 to embed or otherwise engage with the wall 30 of the patient's aorta to anchor the replacement valve 26.
Although the arms 20 are shown as relatively straight wires in the embodiment of the replacement valve 26 described above, the stents of the invention may be shaped and/or positioned differently than previously described. For one example, the stent arms could instead be curved outwardly (i.e., convex) to conform at least somewhat to the location of the body in which it will be positioned (e.g., aorta for aortic valve, pulmonary trunk for the pulmonic vein, vein for venous valve, and ventricle of mitral/tricuspid valve). This outward curvature of the stent arms can help to secure or anchor the valve in place and thus can have different degrees or amounts of curvature depending on the configuration of the particular replacement valve. Further, the barbs or connectors that extend from the stent arms can be positioned near the distal ends of the arms (i.e., spaced relatively far from the valve, such as valve 16), as shown and described above, in order for these connectors to be positioned beyond the sinuses of Valsalva of the aortic valve of a patient. However, the barbs or connectors could alternatively or additionally be located closer to the valve, such as valve 16, which would position the connectors closer to the outflow end of the replacement valve.
FIG. 11 illustrates an optional additional use of a balloon catheter 36 on the delivery device 34 to help to anchor the valve 26 in place in the aorta or other tissue of a patient. In particular, balloon catheter 36 includes a balloon 38, which is located radially between the arms 20 of the stent 18 when the sheath 35 has been retracted from the valve 26. During the process of inserting the device 34 into the patient, balloon 38 will generally be at least partially deflated in order to minimize its size and allow for easier percutaneous insertion of the valve 26. Once the valve 26 is in its desired location relative to the walls 30 with which it will be engaged, the balloon 38 is inflated via the balloon catheter 36. The inflation of balloon 38 can be carefully monitored, such as by measuring pressures of forces, to expand the arms 20 outwardly by a particular amount, thereby driving the barbs or connectors 24 toward and into the wall 30 of the patient's aorta.
While the procedure illustrated in FIGS. 8-11 illustrates placement in the aortic annulus using a percutaneous catheter to deliver the valve retrograde to blood flow, antegrade delivery of the valve is also within the scope of the invention. Similarly, while delivery using a catheter is illustrated, the valve could alternatively be compressed radially and delivered in a minimally invasive fashion using a tubular surgical trocar or port. In addition, as noted above and as will be discussed further below, the valve may be delivered to sites other than the aortic annulus.
FIGS. 12 and 13 illustrate alternative replacement valves that are similar in structure to the valve 26 discussed above, but include alternative structures for anchoring the replacement valve. These replacement valves are again shown in the general location in which they will be positioned within an aortic annulus 28 of a patient. FIG. 12 illustrates a replacement valve that includes the stent 18 having multiple arms 20, but instead of these arms 20 including barbs or connectors, the arms 20 are stent wires that are coupled to a slotted-tube type stent ring 40. As is described above relative to another embodiment, the arms 20 of this embodiment may also be curved outwardly to conform at least somewhat to the location of the body in which it will be positioned. This outward curvature of the stent arms can help to secure or anchor the valve in place. Delivery of this valve can be performed using a procedure that is similar to that described above relative to FIGS. 8-11, or a different method can be used. Alternatively or additionally, some type of adhesive may be applied to the stent ring or a biocompatible covering (e.g., fabric, tissue, polymer, and the like) to help to keep the stent in place. In any case, stent ring 40 may be self-expanding or may be expanded by a balloon or other device that can radially expand the ring 40.
FIG. 13 illustrates a replacement valve that again includes the stent 18 having multiple arms 20. In this embodiment, the arms 20 are coupled to a stent 42 that is formed of one or more zig-zag wires. The wires are arranged relative to each other in such a way that they provide sufficient radial strength to keep the valve in place relative to the aortic annulus 28 or other location to which the valve is delivered. Again, delivery of this valve can be performed using a procedure that is similar to that described above relative to FIGS. 8-11, or a different method can be used. In any case, stent 42 may be self-expanding or may be expanded by a balloon or other device that can radially expand the stent 42.
FIG. 14 illustrates another embodiment of the replacement valve 26 of FIG. 6. In particular, a replacement valve 43 is shown, which includes the same basic structure of the aortic valve 3 of FIG. 2, and further including the stent 18 including arms 20, as in FIG. 5. The tips of the arms 20 of stent 18 are located in the slots 8 and are visible in this top view of the valve 43. The valve 43 further includes optional bulbous portions 44 that extend from each of the tips of the lobes of the tri-lobed structure of the valve 43. These portions 44 are provided to further insure secure contact between the valve 43 and the aorta or other structure in the areas adjacent to the leaflets 2, thereby further minimizing or preventing leakage adjacent the valve commissures. These portions 44 may be made of a tissue, fabric, or other material, as desired.
FIG. 15 illustrates a replacement valve 48, which includes an alternative structure to provide valve leaflets. In this embodiment, leaflets 50 are cut or otherwise formed from a natural or synthetic flexible material (e.g., pericardial tissue, polymeric material, fabric, and the like), and are attached to multiple arms 52 of a stent via sutures, glue, or some other attachment material or method. The leaflets 50 are further attached to one another by means of sutures 54 to define a generally cup-shaped structure. The valve leaflets 50 comprise the regions of the cup-shaped structure located between the longitudinally extending arms 52 of the stent. The arms 52 of the stent can correspond generally to the arms 20 of the stent of FIG. 5, or can be arranged and configured differently. The stent and leaflets could also be constructed together using processes and materials disclosed, for example, in U.S. Pat. Nos. 6,458,153; 6,652,578; and 7,018,408 (all to Bailey et al.), which are incorporated herein by reference. In this embodiment of FIG. 15, the arms 52 are coupled to an expandable slotted tube type stent 56, which may be self-expanding or balloon-expandable similar to the stent 40 of FIG. 12. Other forms of circumferential stents, barbs, or other structures may be used in addition to or as an alternative to the slotted tube type stent structure 56 shown in this figure. Delivery of the valve can correspond generally to the procedure described above relative to FIGS. 8-11, although other delivery devices and methods can be used.
FIG. 16 illustrates another embodiment of a replacement valve 57, which uses the valve leaflet structure of FIG. 15 with a different anchoring embodiment in place of the stent 56. In particular, replacement valve 57 includes stent arms 56a that correspond generally to those of the stent 18 described above, but do not extend as far past the outflow end of the replacement valve as the stent arms of the replacement valve 26 of FIG. 6. Because the valve leaflets 50 of this embodiment present an essentially planar circular free edge, the stent may be anchored to tissue closely adjacent the aortic valve annulus. Barbs, connectors, and/or various forms of circumferential stents may be used in combination with the stent arms 56a to anchor the replacement valve 57 in place. Delivery of the valve 57 can correspond generally to the procedure described above relative to FIGS. 8-11, although other delivery devices and methods can be used.
In the embodiments of FIGS. 15 and 16 described above, the stent arms are illustrated as being positioned in the interior portion of the cup-shaped structure; however, the arms could alternatively be positioned and attached on the outside of the cup-shaped structure. Attachment of the stent to the valve structure could be accomplished by suturing, perforating the wire through the leaflets, adhering, welding, and the like. In any of these embodiments, the method used to attach the leaflets to each other in a cup-shaped structure may be the same or different than the method used to attach a stent either to the inside or outside of this cup-shaped structure
FIG. 18 illustrates another embodiment of a replacement valve 100, which can be fabricated from a piece of flexible tubing, such as is shown in FIG. 17 as a flexible tube 102. Flexible tube 102 may be a natural or synthetic material, such as pericardial tissue, for example (which is discussed, for example, in U.S. Pat. No. 5,482,424, the contents of which are incorporated herein by reference). Replacement valve 100 utilized the flexible tube 102, which is sutured to itself by sutures 60 at an inflow end 104, although other attachment methods may additionally or alternatively be used, such as adhesive or other surgical fasteners. The attachment of the tube 102 to itself produces a tri-lobed structure much like that of the inflow end of the aortic wall 4 of the replacement valve 26 of FIG. 6. However, in this embodiment, the flexible tube 102 is not sutured or attached to itself at an outflow end 106.
The valve 100 further includes a stent that is similar to the stent 18 illustrated in FIGS. 5 and 6, which includes multiple extending arms 20. In this embodiment, the tube 102 is mounted so that the arms 20 extend through slots in the tri-lobed structure and can be attached thereto by sutures, adhesives or other means. However, other stent configurations can also be used, such as using three separate straight wires in substitution for arms 20, which wires can be mounted within the lobes of the tube 102 in its tri-lobed configuration. In any case, the arms 20 or other stent structures can include barbs or connectors 24 for attachment to the walls of an aortic annulus or other tissue structure. As with other embodiments of replacement valve attachment discussed above, self-expanding or balloon expandable stents may alternatively or additionally be attached to or extend from arms 20 for attachment to tissue of a patient.
In this embodiment of a replacement valve 100, the outflow end 106 is not sealed to itself, allowing the downstream portion of the tube located between the arms 20 of the stent 18 to serve as the leaflets of the valve. That is, the replacement valve 100 is illustrated in FIG. 18 in its open position, where blood can flow past the outer surfaces of the valve from the inflow end 104 toward the outflow end 106. Delivery of the valve corresponds to the procedure illustrated in FIGS. 8-11. When the replacement valve 100 is in its closed, position, the outflow end 106 essentially flares outwardly toward the walls of the aorta or other structure in which it is positioned, as will be discussed in further detail below.
FIG. 19 is a top view of the replacement valve 100 of FIG. 18, as located within a patient's aortic annulus 62. In this view it can be seen that the free end of the tube, in conjunction with the arms 20 of the stent 18, define three leaflets 64. In order for the leaflets 64 to properly close, it is desirable to have an entry point for backflow of blood to enter the interior of the tube to expand the leaflets 64. For this reason, the stent and leaflets of this embodiment can be sized so that a small central opening 66 remains open to the interior of the tube, even when the valve is open as illustrated. The same construction may be applied to valves 48 and 57 described above and illustrated in FIGS. 15 and 16.
FIGS. 20-22 illustrate additional exemplary embodiments of the replacement valve of FIGS. 18 and 19. In particular, FIG. 20 is a top view of a replacement valve 110 that allows for fluid entry into the interior of the tube facilitated by a small cylindrical or conical lumen 69, which is mounted in the interior portion of the stent. Lumen 69 acts as a type of a spacer to keep the leaflets 64 freely moveable relative to each other, thereby facilitating closing of the valve 110 with sufficient pressure from blood flow. That is, when the blood flow moves in a “backward direction relative to the pumping blood flow, it should move the leaflets 64 apart from each other and toward the aortic annulus or other structure in which it is positioned, thereby closing the valve 110.
FIG. 21 is a top view of a replacement valve 120 that allows for fluid entry into the interior portion of the tube at the commissures of leaflets 64 to facilitate closing of the valve 120. Small openings between the lobes of the structure are provided by means of enlarged segments on the arms 20a of the stent. FIG. 22 illustrates an enlarged detail of a portion of the embodiment of FIG. 21. In this view, an enlarged cross section portion of arm 20a of the stent and the associated small opening 68 are visible. All of these alternative constructions of FIGS. 20-22 may be applied to valves 48 and 57 described above and illustrated in FIGS. 15 and 16, along with other valves. Other structures may be used in addition to or instead of the devices of FIGS. 19-22, any of which should facilitate the closing of the valve.
FIG. 23 illustrates a replacement valve 130 that can be fabricated from the tube 102 of FIG. 17, for example. Valve 130 has its inflow end 122 sutured to itself to produce a flattened structure and is mounted to a stent. The stent may be a self-expanding stent taking the form of a u-shaped wire 70 having laterally extending barbs 72. The contours of the wires 70 can also be used to further secure the valve into its position within the patient. Alternatively, the stent may comprise two separate straight wires. The free end of the tube in conjunction with the stent defines two valve leaflets 74 which, when open, expand against the vessel or orifice in which the replacement valve is mounted. Delivery of the valve corresponds to the procedure illustrated in FIGS. 8-11, although other delivery devices and methods can instead be used.
FIG. 24 illustrates a detail of the replacement valve 130 of FIG. 23. As with the valve of FIG. 18, an inflow opening into the interior of the valve may be desirable to facilitate separation of the valve portions from each other to close the valve 130. In some embodiments, this might be provided by enlarged cross section portions of the wire 70. In alternative embodiments in which the free edges of leaflets are attached directly to a valve orifice 76, a simple staple 78 may be substituted, also providing an opening into the valve 130. Staple 78 may be attached to the stent and may self expand into the tissue of the annulus or may be balloon expanded, for example.
FIG. 25 illustrates the replacement valve 130 of FIG. 23, which is folded to allow passage through a catheter or other tubular delivery device. In this embodiment, the u-shaped stent wire 70 or other stent configuration is coupled to an expandable stent 80. By folding the replacement valve 130 rather than circumferentially compressing it, stress on the valve 130 is reduced.
FIG. 26 illustrates an alternative stent configuration 79 for use with the leaflets of the above FIGS. 15-24. In this design, rather than employing multiple curved, longitudinally extending arms or wires, a single longitudinally extending wire 86 is used. Wire 86 includes an enlarged base 88 against which the inflow end of the valve leaflets rest. The commissures and thus the valve leaflets 80 are defined by two or three laterally extending wires 82, which are attached to the edges of the valve leaflets 80. The laterally extending wires 82 are provided with barbs or connectors 84 which anchor the replacement valve in place within the vessel or orifice in which it is implanted.
FIGS. 27 and 28 illustrate additional features that can be used with a replacement valve of the type described relative to valve 130. In particular, a replacement valve 140 is formed from a tube of material to create a bicuspid valve structure, as in FIG. 23. The valve has its inflow end sutured to itself to produce a flattened structure with a central longitudinal opening 148 in which a stent 146 is positioned. Again, the stent 146 may take the shape of a u-shaped wire with laterally extending barbs or connectors, or another stent configuration can be used. In any case, the stent 146 of this embodiment works in conjunction with the size of the slot 148 to provide at least a slight gap between the opposing leaflets 144. The slot 148 helps to facilitate opening of the leaflets 144 when the blood flows from the outflow end of the valve toward the inflow end, thereby closing the valve 140.
FIG. 28 illustrates a replacement valve 150 that is similar to valve 140, except that valve 150 includes a slot 152 that is not particularly designed to include a space between opposing leaflets 154. In order to facilitate separation of the leaflets 154, this valve 150 includes pockets 156 at both ends, which can be formed by the ends 158 of a stent positioned therein. For example, these ends 158 may be enlarged relative to the stent wire so that the stent can operate in its normal manner while the enlarged ends operate to form the pockets 156.
While a number of the valves described above are shown as having fixation barbs located downstream of the free edges of the valve leaflets, this need not necessarily be so. In fact, the planar, generally circular configuration of the free edges of the valve leaflets in the closed position would in some cases allow the barbs or connectors to extend outward through or adjacent to the free edges of the valves. Further, while the discussion of the valves above focuses mainly on placement in the aortic annulus, the valves may be employed in other locations including replacement of other heart valves and peripheral venous valves. Finally, while the valves as disclosed are described mainly in the context of percutaneously or minimally invasively delivered valves, they could also be placed surgically.
The present invention has now been described with reference to several embodiments thereof. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein.
