US 20050065601 A1
An annuloplasty system for repairing a valve in a patient's heart comprises a surgical implant including a member having first and second end portions. The implant member further is configured and/or adapted to form a partial ring along a portion of one of the valve annulae of a patient's heart such as the mitral or tricuspid valve annulus. The implant member is axially elastic such that it can axially expand and contract and includes first and second anchors extending from the end portions of the implant member. The anchors are adapted to anchor the implant in tissue such as the mitral or tricuspid valve annulus. The system can facilitate tissue plication (e.g., of the posterior annulus of the mitral valve or the annulus of the tricuspid valve) and reinforcement of a valve annulus.
1. An annuloplasty system for repairing a valve in a patient's heart, said annuloplasty system comprising a surgical implant having first and second ends, first and second anchors, and a needle, said implant having a plurality of curves pre-formed therein and being adapted to form a partial ring along a portion of one of the valve annulae of a patient's hear; said annuloplasty system having a first state for placing said implant along said portion of one of the valve annulae and a second state for securing said implant to said portion of one of the valve annulae with said anchors; when said annuloplasty system is in said first state, each one of said anchors is coupled to a different one of said implant ends with at least one of said anchors being exposed, said implant ends are uncoupled from one another, and said needle is releasably coupled to one of said implant ends; and when said annuloplasty system is in said second state, said implant ends remain uncoupled from one another and said needle is uncoupled from said one of said implant ends.
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The invention relates to heart valve repair and particularly to annuloplasty apparatus and methods. The invention is especially useful in mitral valve annuloplasty procedures, which generally involve mitral insufficiency (e.g., regurgitation when the mitral valve does not properly close).
Essential to normal heart function are four heart valves, which allow blood to pass through the four chambers of the heart in one direction. The valves have either two or three cusps, flaps, or leaflets, which comprise fibrous tissue that attaches to the walls of the heart. The cusps open when the blood flow is flowing correctly and then close to form a tight seal to prevent backflow.
The four chambers are known as the right and left atria (upper chambers) and right and left ventricles (lower chambers). The four valves that control blood flow are known as the tricuspid, mitral, pulmonary, and aortic valves. In a normally functioning heart, the tricuspid valve allows one-way flow of deoxygenated blood from the right upper chamber (right atrium) to the right lower chamber (right ventricle). When the right ventricle contracts, the pulmonary valve allows one-way blood flow from the right ventricle to the pulmonary artery, which carries the deoxygenated blood to the lungs. The mitral valve, also a one-way valve, allows oxygenated blood, which has returned to the left upper chamber (left atrium), to flow to the left lower chamber (left ventricle). When the left ventricle contracts, the oxygenated blood is pumped through the aortic valve to the aorta.
Certain heart abnormalities result from heart valve defects, such as valvular insufficiency. For example, mitral valve insufficiency, also known as mitral regurgitation, is a common cardiac abnormality where the mitral valve leaflets do not completely close when the left ventricle contracts. This allows blood to flow back into the left atrium, which then requires the heart to work harder as it must pump both the regular volume of blood and the blood that has regurgitated back into the left atrium. Obviously, if this insufficiency is not corrected, the added workload can eventually result in heart failure.
One option to correct valve defects is complete valve replacement. This intervention, however, is quite invasive and traumatic. There are more conservative surgical interventions that are less traumatic than implanting valvular prostheses. These approaches include valve leaflet repair, chordae tendinae shortening or replacement, and or valve annulus repair also known as annuloplasty. One example where annuloplasty procedures have been developed is in the field of mitral valve insufficiency correction.
Mitral valve insufficiency typically results from a change in the size and shape of the mitral valve annulus. Mitral valve annuloplasty involves reestablishing the normal shape and size of the mitral valve annulus so that it can effect full closure of the valve leaflets.
There have been a number of annuloplasty approaches to repair the mitral annulus of a patient's heart. Dr. Norberto G. De Vega developed a procedure in the early 1970s. One laces a suture along the periphery of a compromised portion of the heart valve. The suture is drawn in a “purse string” manner to cinch the tissue and reduce the size of the valve opening. Then the suture ends are knotted. Although the procedure can reduce the size of the valve opening and improve valve efficiency, it is not free from drawbacks. One disadvantage of this approach is that the sutures can pull out of the tissue and “guitar sting” across the valve annulus. The purse string also may cause tissue bunching, which may distort the natural shape of the valve.
Other approaches to improve valve function (e.g., with the mitral or tricuspid valves) include tissue plication devices and reinforcement of the valve annulus with annuloplasty rings. These approaches also are claimed to reestablish the original annulus size and shape and/or prevent further annulus dilation.
Both rigid and flexible annuloplasty rings have been developed. Rigid rings, which generally tend to dictate the shape and contour of the mitral valve annulus, have been considered to somewhat compromise the natural flexibility of the annulus. Flexible annuloplasty rings emerged to provide some degree of compliance in the valve annulus so that the valve could maintain normal physiological motion throughout the cardiac cycle of a beating heart. This is in addition to providing annulus reinforcement. However, it is believed that among the drawbacks of these rings is that they may fold or crimp during implantation and thereby undesirably reduce the size of the valve (e.g., mitral) opening. Also, the sutures used to secure the ring may cause scarring and stiffening of the valve annulus and reduce annulus flexibility over time.
C-shaped bands or partial annuloplasty rings also have been developed. These devices can be attached solely to the posterior portion of the valve annulus which eliminates the need to attach material to the anterior portion of the annulus. The annulus is fibrous and generally does not require plication and/or reinforcement. Thus, the partial rings can preserve the normal function of the anterior portion of the annulus. Full and partial ring devices are disclosed, for example, in U.S. Pat. No. 3,656,185, which issued to Carpentier.
Other attempts to improve upon valve repair procedures, including the De Vega approach and the use of rigid, flexible, and partial rings, include that described in U.S. Pat. No. 5,450,860, which issued to O'Connor, U.S. Pat. No. 6,183,512B1, which issued to Howanec, Jr. et al., and U.S. Pat. No. U.S. Pat. No. 6,250,308B1, which issued to Cox.
The O'Connor patent discloses a plication approach, particularly suitable for use with an annuloplasty operation on heart valves (e.g., mitral or tricuspid valves). The approach involves a ligament, which can comprise a wide, flexible strip of expanded polytetrafluorethylene or similar material, and sutures to retain the ligament in place. The ligament has at least an end of constricted diameter and a needle attached thereto, or it can have two constricted ends and a needle attached to each of the ends. This construction permits the ligament to be drawn through an area of tissue to be plicated. Once in place, a first end of the ligament is anchored, preferably with sewing of conventional sutures through the ligament, and the tissue is cinched along the length of the ligament to provide the desired amount of plication. Once the tissue is correctly oriented, the second end of the ligament is then likewise anchored in place, again preferably through the use of a suture sewn through the ligament.
The Howanec patent describes a system that includes an elongate flexible band with a needle attached to one end of the band and a fit adjuster attached to the other end of the band. The needle is used to introduce the band into the atrioventricular groove (hereafter “AV groove”) and then pull a portion of the band out of the tissue. After the band is so implanted into the AV groove, a fit adjuster is used to couple the exposed ends of the band and size and position the band in the annulus. After the band is pulled to cinch the tissue in the AV groove until the valve annulus is reconfigured to an optimal shape, the band can be secured to the valve annulus with sutures and the exposed portions of the annuloplasty system removed.
The Cox patent describes a system that comprises a combined annuloplasty ring implant, which has a rigid section and a flexible section. A needle is coupled to one end of the implant. The needle facilitates introducing the implant into the fatty pad of the AV groove, which surrounds the valve annulus, at one end of the posterior portion of the annulus and pulling one end portion of the implant out of the AV groove in the vicinity of the other end of the posterior portion of the annulus. The flexible section of the ring extends adjacent to the flexible posterior portion of the annulus, while the rigid section of the ring spans the substantially rigid inter-trigone section of the annulus. Cox advances that with this procedure one need not suture the flexible section directly to the mitral valve annulus, thereby substantially eliminating scarring and stiffening of the annulus. In one example, the flexible material is also elastic to accommodate the expansion and contraction of the annulus, in addition to flexing. The system further includes means for joining the ends of the ring, which are positioned along the inter-trigone section, after the needle is removed. Sutures can be added to secure the annuloplasty ring to the annulus, for example, along the inter-trigone section.
Other plication and valve repair approaches are disclosed in PCT International Patent Application Nos. PCT/US01/42653 and PCT/US01/31709, which are co-owned by the assignee of the present invention and entitled “Minimally Invasive Annuloplasty Procedure and Apparatus” and “Minimally Invasive Valve Repair Procedure and Apparatus,” respectively. These approaches, in-part, address various inherent disadvantages with prior open heart surgical procedures as described, for example, by F. Maisano, et al. in their article entitled “The double-orifice technique as a standardized approach to treat mitral regurgitation due to severe myxomatous disease” which appeared in European Journal of Cardio-thoracic Surgery, Vol. 17 (2000) 201-205. Disadvantages associated with such open-heart procedures include cumbersome suture management, timely knot tying steps, pain, and long recovery time.
Generally, known annuloplasty ring and band recipients are required to undergo anticoagulation therapy for a minimum of several months post-operatively due to the high risk of prosthesis-induced thrombosis. However, anticoagulation therapy increases the risk of bleeding complications due to the inhibition of blood clot formation.
Applicants believe that there remains a need for improved valvular repair apparatus and methods.
The present invention involves annuloplasty systems that avoid problems and disadvantages of the prior art. The present invention involves an annuloplasty system for repairing a valve in a patient's heart. The system comprises a surgical implant, which includes a member having first and second end portions. The implant member further is configured and/or adapted to form a partial ring along a portion of one of the valve annulae of a patient's heart such as the mitral or tricuspid valve annulus. The implant member is axially elastic such that it can axially expand and contract and includes first and second anchors extending from the end portions of the implant member to anchor the implant in tissue such as the mitral or tricuspid valve annulus. The system can facilitate tissue plication (e.g., of the posterior annulus of the mitral valve or the anterior annulus of the tricuspid valve) and reinforcement of a valve annulus.
The partial ring configuration may reduce or minimize the risk of stenosis as compared to more bulky systems using full rings. This configuration also can reduce the amount of prosthetic material that is exposed to blood flow, thus, minimizing or eliminating the requirement for post-operative anticoagulation. Further, since the ends are not joined, the surgeon need not place anything on the anterior portion of the annulus (in the case of mitral valve repair), which otherwise could obstruct flow intake.
According to another aspect of the annuloplasty system, clips can be used in lieu of sutures to anchor or fasten the implant in the desired position. This eliminates cumbersome suturing approaches, simplifies implantation as compared to conventional methods, and facilitates minimally invasive (e.g., endoscopic) approaches to valve annuloplasty (e.g., mitral or tricuspid valve annuloplasty).
According to one embodiment of the invention, the implant member has a small cross-sectional dimension, but it is curved to form an implant of much greater overall transverse dimension or diameter. In this embodiment, the implant member can comprise a wire formed to have, for example, an undulating configuration adapted for implantation within the valve annulus. The implant wire with a wire diameter, for example, can range from about 0.002 to 0.062 inches, yet have an overall transverse dimension (measured from peak to trough) of about 0.010 to 0.375 inches. Preferably, the overall transverse dimension, which also may be described as the width or amplitude of the undulating member, taken along a portion of the implant is about 5 to 10 times greater than the implant wire diameter. This construction facilitates implant stability and proper implant orientation with respect to the annulus, while minimizing implant bulk, which, in turn, can reduce or eliminate the risk of prostheses induced thrombosis.
The curved wire construction of the present invention also can be configured to provide desirable flexibility so that the implant can comply with annulus flexure during normal cardiac function. The implant also can be configured to be axially elastic or compliant. With such axial elasticity, the implant can expand and contract to accommodate annulus expansion and contraction during relaxation (i.e., expansion) and contraction of the left ventricle.
According to a further embodiment of the invention, the implant member can comprise a wire formed to have a plurality of loops formed therein. Anchors or sutures can be attached to the loops and tissue to secure the implant member to the tissue. The wire diameter typically is about 0.002 to 0.062 inches and the diameter of the loops preferably range from about 0.010 to 0.050 inches. As the annulus is secured to the loops, it conforms to the implant shape, which can be configured to reshape the annulus toward or to its original size and shape to improve or correct cardiac function.
According to a further aspect of the invention, a needle can be releasably coupled to one end of the implant. The needle simplifies implant delivery and avoids the need for time-consuming suture procedures.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings, wherein, for purposes of illustration only, specific forms of the invention are set forth in detail.
Referring to the drawings wherein like numerals indicate like elements,
The distal end of the implant member may have an enlarged portion 110 as shown in the drawings. A stopper or anchor 112, preferably in the form of a disc and preferably welded to the distal end of the implant member, may be provided adjacent to the enlarged portion 110. Similarly, another stopper or anchor 114 may be provided adjacent to the implant's proximal enlarged portion 116 as shown in
A flexible tubular member 104 is provided between needle 106 and release mechanism sleeve 124. Specifically, one end oftubular member receives one end of release mechanism sleeve 124. Release mechanism sleeve 124 is sufficiently flexible so that it can slide within tubular member 104 as it is retracted or removed from the bundle of cables or arms 122 to release enlarged portion 116 and, thus, implant member 102 as will be described in more detail below. The other end of tubular member 104, together with the end of wire 136 is inserted in a recess 146 (
Returning to the embodiment of
Referring to FIGS. 3A-C, proximal stopper or anchor 114, which also may be referred to as a retainer, is shown in further detail. Stopper 114 can be formed from a tube by removing two half tubular sections as shown in the drawings. One can remove one have tubular section along one section of the tube and another half tubular section along another section of the tube on the other side thereof as illustrated in FIGS. 3A-C. As shown, surfaces 112(a) and 112(b) can be angled to simplify the material removal process in forming stopper 112.
Although a particular implant configuration has been shown, other configurations can be used without departing from the scope of the invention. Referring to
The wire diameter can vary from application to application. For example, when applied to normal human mitral valves, it can range from about 0.002 to 0.062 inches, more preferably in the range of about 0.005 to 0.015 inches, and typically will be about 0.089 inches. The wire diameter range is the same when applied to tricuspid valves. The transverse dimension or width “W” (
The implant or implant wire preferably comprises a shape memory alloy or elastic material. As is well known in the art, shape memory material has thermal or stress relieved properties that enable it to return to a memory shape. When stress is applied to shape memory alloy material causing at least a portion of the material to be in its martensitic form, it will retain its new shape until the stress is relieved. Then it returns to its original, memory shape. On the other hand, when shape memory material is cooled to where it is in its martensitic form and then deformed, it retains the deformed shape until its temperature is increased so that the material becomes austenitic. Then it returns to its original, memory shape. One preferred shape memory material for the implant member is nitinol.
The shape memory wire (e.g., nitinol) can be shape set into the undulating configuration by weaving the wire through a fixture having a row of rods and affixing the two ends of the nitinol wire under tension. Alternatively, the nitinol wire can be shape set by press molding using a mold with a crimped pattern. The heat treatment to permanently set the shape of the nitinol wire can be achieved by heat-treating in either a convection oven or bath at a temperature range of 100 to 600° C. for a duration of 2 to 20 minutes. In assembling the system the distal stopper can be welded to one end of the shape set imbedded wire. The retractable stopper is loaded onto the proximal end of the imbedded wire. A ball is formed onto the proximal end of the imbedded wire by welding. The release mechanism is assembled with a flexible member and a taper component to transition from the flexible member to the release mechanism. The release mechanism is attached to the ball of the imbedded wire at the proximal end and the retractable stopper is placed into its retracted position within the release mechanism component. Then, a needle is swaged onto the flexible member.
The leaflets open and close in response to pressure differences on either side of thereof. However, when the leaflets do not fully close, regurgitation and valve insufficiency can result. One method to treat the insufficiency using the annuloplasty system of
In the embodiments described above, the implant member returns to its memory shape upon stress release (i.e., actuation of release mechanism 108). As the implant is inserted, the tissue and pulling forces placed on the device to pull it into position cause it to axially expand. Once in position, the release mechanism is actuated, thereby removing the pulling force and allowing the implant to axially contract toward its memory shape.
Alternatively, the device can be designed to have thermal properties to return to its memory shape at a predetermined temperature. It can be deformed at a first temperature to generally remove or reduce the amplitude(s) or period(s) of the undulations and then inserted into the tissue. After insertion, its temperature rises to the predetermined temperature and it assumes its original, undulating memory configuration. As it returns to its memory shape, it axially contracts and decreases the circumferential dimension of the valve annulus.
Although particular configurations have been illustrated, other configurations can be used without departing from the scope of the invention. For example, the wire can be flat. The undulations can have varying or changing amplitude or frequency. The radius of the crests and troughs also can vary from implant to implant or within a single implant. Further, the implant wire can be a single length of wire as shown in the drawings or it can be made up of multiple lengths of wire joined together.
The undulating implant can provide high strength and elasticity to material volume (or diameter) ratio. The implant configuration and construction can provide desirable elasticity that allows for physiological motion in the linear direction (annular dilatation) and planar surface. Since the undulating member can be self-terminating at the trigones, it does not require knot tying, connectors, or cutting. The implant can be less traumatic to the annular tissue as compared to other devices. For example, it does not require multiple suture passes. The implant configuration and placement also can minimize the amount of implant surface that comes into contact with blood flow.
Implant member 202 can be straight (not shown), or crescent or arc-shaped so as to form a partial ring as shown in
With the exception of one of the surgical clip ends being secured to implant member 202, each anchor-clip, release mechanism, flexible member and needle combination forms a tissue connector assembly 214 similar to tissue connector assemblies described in U.S. patent application Ser. Nos. 09/089,884 and 09/090,305 both filed Jun. 3, 1998 and Ser. Nos. 09/259,705 and 09/260,623 both filed Mar. 1, 2000 and International Application Nos. PCT/US99/12563 and PCT/US99/12566 both filed Jun. 3, 1999 and published under International Publication Nos. WO 99/62409 and WO 99/62406, all of which are hereby incorporated by reference herein. Although one tissue connector assembly configuration is shown herein, any other suitable assemblies described in the applications cited in the preceding sentence can be used.
The applications cited in the previous paragraph describe tissue connector assemblies having self-closing clips, which can be characterized as having two end points, which tend to come closer together either by elasticity or so-called pseudoelasticity. Such a clip may be made by heat-treating a NiTi wire to a certain temperature and time to have a desired undeformed shape. The surgical clip generally comprises a wire, preferably, comprise shape memory alloy. In the present invention, each clips preferably has two end points, an unbiased closed configuration, the ability to be moved or biased to an open configuration, the tendency to return to the naturally closed memory configuration, which reduces the separation between the two end points as compared to the spaced end point orientation when the clip is in an open configuration.
The clips disclosed in aforementioned U.S. and PCT patent applications describe a clip comprising a deformable wire made of a shape memory alloy, which clip can assume a U-shape when in the open configuration and one example of a suitable clip for this embodiment of the present invention.
Such a clip may be deployed, for example, in the form of a single-arm clip assembly as shown in
The ends of the clip coil 204(b) are constrained with the coil in compression to urge or bias clip wire 204(a) into a generally U-shaped open configuration.
A release mechanism 208, such as disclosed in aforementioned U.S. patent application Ser. No. 09/260,623 (or International Application No. PCT/US99/12566, which published on Dec. 9, 1999 under International Publication No. WO 99/62406 is provided so that clip wire 204(a) can readily be released by squeezing the release mechanism with a surgical instrument. One suitable release mechanism is specifically described in International Application No. PCT/US99/12566 from page 25, line 12 through page 27, line 30 ending with the text “mechanism 23c” (but without the text “such as needle 17 as shown in FIG. 1” on line 27 of page 27) and the referenced figures are hereby incorporated by reference herein. A summary of such a release mechanism is provided below with reference to
According to one method of making the device, the loops and the general curve shape of member 202 are made from the same piece of wire. The loops are formed by wrapping the wire around mandrels. The mandrels are arranged in the general curve shape, thus giving the appearance of loops superposed onto a general curve shape. Wire cross section diameters can range from about 0.002 to 0.062 inches. Loop diameters can range from about 0.010 to 0.050 inches. The radius of curvature of the overall implant member 202, having loops formed therein, can range from about 0.25 to 1.25 inches, but can be made to any radius. The straight-line distance between the ends of the implant member 202 (between washers 224) ranges from about 0.5 to 2.5 inches. The length of the implant member (measured from washer 224 to washer 224) can range from about 0.75 to 3.0 inches. The profile is essentially the thickness of prosthetic material attached to the annulus. The smaller the diameter, the lower the profile. Lower profile may prevent nonphysiological blood flow, which can lead to undesirable hemodynamic effects, e.g., thrombosis, disruption of red blood cells, or slower tissue healing. When the surgical clip is made from the same piece of wire as the multilooped member, the last loop is the one that abuts washer 224, which is passed onto the multiloop member and crimped to act as a stopper for the coil 204(b), which surrounds a portion of the wire that forms the implant member and surgical clip. The release mechanism 208 compresses the coil against washer or constraint 224, which maintains the surgical clip in a U-shaped configuration.
Then discrete or individual tissue connector assemblies 214 are passed through loops 212 (
The attachment loops provide elasticity and act as torsion springs. The spring properties generally provide elasticity. In the deployed condition, the implant, having shape memory to regain its original unloaded length, applies a recoil force to draw the two ends together along the length of the implant. In the implanted condition where the implant wire is loaded to an elongated configuration, the shape memory force draws the annulus together resulting in tissue plication and a reduction in annulus size. The preloaded condition of the implant wire continues to provide a reinforcement force to prevent further dilation of the valve annulus. Furthermore, the elastic nature of the loops allow for the natural compliance and physiological motion of the annulus.
The low profile characteristic of the implant as compared to conventional annuloplasty rings or bands reduces the amount or volume of prosthetic material that is exposed to blood flow. This can substantially reduce the need for post-operative anticoagulation therapy.
Although annuloplasty system 200 has been described with self-closing clip type anchors, other surgical clips can be used as anchors such as that disclosed in U.S. Pat. No. 5,972,024, which issued to Northrop, III et al. Further, sutures can be used to form the anchors as will be discussed in more detail below.
Although a particular system embodiment having two clip anchors, release mechanisms, and delivery needles has been described and illustrated in FIGS. 8A-C, variations of this system can be made within the scope of the invention. For example, only one clip anchor, release mechanism, and delivery member may be used. In this case, the clip anchor with its release mechanism and delivery needle can be coupled to one end of the implant member as shown in
In yet a further case, both clip anchors and their release mechanisms and delivery needles can be eliminated and both ends of the implant member constructed to end in a loop as described above. Both loops can then be fastened to the tissue using a suture or clip as described with respect to the previous example.
In another variation, the implant member can be a full ring and the loops secured to tissue thereunder.
More specifically, when constructed for holding a clip or anchor, the holding mechanism or member(s) can comprise multiple strands, cables or wires 122 having a radially outward bias as shown in
The hypodermic halves shown in FIGS. 13A-D, also have cut out portions that form arms 240 and collars 242. Collars 242 surround wire 136 and have inner diameters less than the diameter of enlarged portion or ball 134 to secure halves 122′ to wire 136. In this manner, the delivery apparatus can be readily removed, while leaving the clip or anchor at the desired site.
The one-piece hypodermic tubing embodiment of FIGS. 14A-D, has a cut out to form a longitudinal opening for releasing a clip or anchor 204 from holding member 122″. The tubing also has cut outs to form arm 240′ and collar 242′ having an inner diameter less than the diameter of enlarged portion or ball 134 to secure the tubing to wire 136 and facilitate removal of the delivery apparatus, while leaving the clip or anchor at the desired site.
While the invention has been described with reference to specific embodiments, the invention by no means is limited to the specific embodiments illustrated and described herein. It is recognized that departures from the disclosed embodiments may be made within the scope of the invention and that obvious modifications will occur to a person skilled in the art. Accordingly, all suitable modifications and equivalents may be resorted to to the extent that they fall within the scope of the invention and claims appended hereto.