Method of implanting a self-molding annuloplasty ring

[0001] The present application is a continuation of Ser. No. 09/938,902, filed Aug. 24, 2001, now U.S. Pat. No. 6,726,716 entitled SELF-MOLDING ANNULOPLASTY RING, which application is expressly incorporated herein by reference.

[0002] The human heart is hollow muscular organ having four pumping chambers separated by four heart valves. The mitral and tricuspid valves, present at the left and right atrio-ventricular junctions, open and close in response to a pressure gradient during each cardiac cycle of relaxation and contraction to control the flow of blood to a particular region of the heart

[0003] These valves are comprised of a dense fibrous ring known as the annulus, leaflets or cusps attached to the annulus, and a complex of chordae tendineae and papillary muscles securing the leaflets. The size of the leaflets or cusps is such that when the heart contracts the resulting increased blood pressure formed within the ventricular cavity forces the leaflets towards the arterial cavity. As a result, the leaflets or cusps come in apposition to each other thereby closing the atrio-ventricular passage.

[0004] Natural defects and heart disease are common causes of valvular dysfunction within the heart of a patient. One common example of valvular dysfunction occurs when the annulus becomes excessively dilated or the valve geometry results in ineffective valve closure, which results in regurgitation. Due to the increased diameter of the annulus, the leaflets or cusps fail to meet during systolic contraction, thereby resulting in the regurgitation of blood during ventricular contractions. As such, sufficient back pressure exists within the chambers of the heart capable of forcing some blood flow to traverse the atrio-ventricular junction from the ventricle to the atria.

[0005] One manner of repairing this problem involves surgically implanting a prosthetic ring (i.e. “annuloplasty ring”) about the dilated annulus, thereby restoring the annulus to the normal size and shape and allowing the valve leaflets to function normally. Commonly, a surgeon positions the annuloplasty ring near the valve annulus and sutures the device in place.

[0006] One approach to correcting or remodeling the valve annulus has required the implantation of a rigid annuloplasty ring. Typically, an annuloplasty ring having the desired internal diameter is positioned near the heart valve and sutured in place. As a result, the diameter of the valve is reduced to the diameter of the annuloplasty ring. This procedure utilizing current annuloplasty rings has several shortcomings. For example, the tissue comprising the heart, particularly in the area of the heart valves, is flexible. The implantation of a rigid annuloplasty ring restricts the natural flexibility of this tissue, and may impact the heart's function. Also, the diameter of the dilated annulus is substantially larger than the annuloplasty ring, thereby making the implantation surgery unnecessarily time consuming. The surgeon is required to position the prosthesis near a portion of the tissue and suture the ring in place. Thereafter, the opposing tissue is forced to engage the ring and is attached to the annuloplasty ring with sutures. Consequently, the sutures may be under different stress loads, and could result in an increased risk of ring dehiscence.

[0007] There is thus a need for a flexible annuloplasty prosthesis and implantation device which enables a surgeon to precisely position and apply an annuloplasty ring to the dilated valve annulus.

[0008] The present invention solves the aforementioned problems in that the resilient annuloplasty ring of the present invention may be stretched to the diameter of the dilated valve annulus prior to implantation, thereby simplifying the implantation process. In addition, the contractive force of the resilient annuloplasty ring of the present invention may controllably reduce the diameter of an incompetent dilated valve annulus to more competent diameter. Those skilled in the art will appreciate the present invention is easy to manufacture and may be manufactured from a plurality of materials.

[0009] The annuloplasty ring of the present invention comprises a resilient inner sizing member positioned within a flexible outer attachment sheath. The resilient inner sizing member applies a contractive force to the incompetent annulus tissue. The flexible outer attachment sheath permits the surgeon to attach the device to the annulus tissue in a plurality of manners including suturing and stapling. The annuloplasty ring of the present invention may be manufactured from a plurality of biologically compatible materials having sufficient resiliency to permit stretching during implantation and having sufficient contractive force to permit a reduction in the diameter of the incompetent valve annulus.

[0010] An alternate embodiment of the present self molding annuloplasty ring comprises an resilient inner sizing member positioned within a flexible outer attachment sheath, the ring further having a plurality of attachment members positioned thereon. The attachment members may comprise a plurality of devices, including, without limitation, needles, barbs, or hooks. In addition, the attachment members may be manufactured from a biologically compatible material such as, without limitation, stainless steel, titanium, and Nitinol.

[0011] In yet another embodiment of the present invention, a self molding annuloplasty ring having a predetermined contracted diameter is disclosed. This embodiment comprises a resilient inner sizing member positioned within a series of individual support members. A flexible outer attachment sheath is positioned on the exterior of the support members. This embodiment permits the surgeon to predetermine the inner diameter of a repaired valve annulus, thereby rendering an incompetent valve competent. Those skilled in the art will appreciate that the support members may be manufactured from a biologically compatible material such as, without limitation, plastic and elastomer.

[0012] Other objects, features, and advantages of the present invention will become apparent from a consideration of the following description of the preferred embodiments.

[0027] The following detailed description and the accompanying drawings are intended to describe and show certain presently preferred embodiments of the present invention, and are not intended to limit the scope of the invention in any way.

[0028] The self-molding annuloplasty ring of the present invention is generally used in surgical procedures to repair an incompetent tissue annulus. More specifically, the present invention is used to render an otherwise incompetent heart valve competent by decreasing the diameter of the opening at the valvular junction. As those skilled in the art will appreciate, the present invention may be manufactured with varying degrees of pre-tension and contractive force, thereby permitting variations of the contraction of the anterior and/or posterior annuli. In addition, the present invention simplifies the implantation procedure by permitting pre-stretching of the annuloplasty ring to the diameter of the dilated annulus, and thereafter reducing the annulus with the contractive force exerted by the self-molding annulus ring.

[0029] FIG. 1 shows a cross sectional view of the heart 10 having a bicuspid or mitral valve 12 positioned near the mitral valve annulus 14, and a tricuspid valve 16 positioned near the tricuspid valve annulus 18.

[0030] Various views of the present invention are illustrated in FIGS. 2A–2E. As shown in FIG. 2A, the self-molding annulus ring 20 comprises a first planar surface 22 and an opposing second planar surface 24. FIG. 2B shows the annulus ring 20 having a rectilinear segment 26 and an arcuate segment 28 connected by two curved ends 30 and 32, respectively. As illustrated, the preferred annuloplasty ring 20 is generally “D” shaped to conform to the shape of a typical mitral valve annulus. Alternatively, the ring 20 may be manufactured in any shape suitable for implantation about an annulus. For example, the present invention may be manufactured in a generally round or oval shape thereby permitting use of the present invention to remodel an otherwise incompetent tricuspid valve. FIG. 2C shows a cross-sectional view of the annuloplasty ring 20 having an elastic sizing member 36 positioned within an attachment sheath 38. While the cross-sectional view illustrated in FIG. 2C is substantially rectangular, it is to be appreciated that the cross-section can alternatively be of another dimension such as triangular, circular or any dimension that cooperates with the native annulus.

[0031] The elastic sizing member 36 preferably comprises a biologically-compatible materials such as, without limitation, elastomer, silicon, or any other material having sufficient resiliency to permit pre-stretching of the annuloplasty ring 20 prior to and during implantation, while having sufficient contractive force to decrease the size of the valve annulus to a desired diameter. The attachment sheath 38 provides a suitable material for suturing or otherwise attaching the annulus ring 20 to the annulus tissue and promoting tissue growth therein. The attachment sheath 38 preferably comprises a biologically-compatible material such as, without limitation, Dacron (polyethylene terepthalate), polyester knit, PTFE knit, and ePTFE knit. The attachment sheath may also be treated with a biologically-compatible tissue growth factor or other medicament to aid in treating the attachment area. Those skilled in the art will appreciate that the present invention reduces or eliminates the occurrence of systolic anterior motion (SAM), wherein the anterior leaflet of the mitral valve bulges into the left ventricular outflow track (LVOT) thereby obstructing blood flow into the aorta.

[0032] An alternate embodiment of the present invention is shown in FIG. 2D having support members 40 positioned between the sizing member 36 and the attachment sheath 38. The support members 40 are preferably fabricated from a biologically-compatible materials having a comparable modulus of resiliency such as, without limitation, elastomer, rubber, silicon, or another material having sufficient resiliency to permit pre-stretching prior to implantation while sufficient providing support to the valve annulus. The support member 40 provides additional support of the valve and valve annulus FIG. 2E shows a perspective view of the annuloplasty ring of the present invention.

[0033] The annuloplasty ring of the present invention may be attached to the annulus or surrounding tissue using a plurality of devices. Referring to FIG. 3A, the annulus ring 20 may be attached to the valve annulus, either 14 or 18, with sutures 42. FIG. 3B shows an alternate embodiment of the present invention utilizing attachment devices positioned on the annuloplasty ring. Like the previous embodiments, the present embodiment of the ring 44 comprises a rectilinear segment 46 attached to an arcuate portion 48 with two curved ends 50 and 52 positioned therebetween. A number of attachment devices 54 are positioned around the ring 44 to facilitate attachment of the ring 44 to the annulus tissue. FIG. 3C shows the internal materials of the present invention having a sizing member 56 and an tissue-engaging sheath 58 disposed thereon.

[0034] Like the previous embodiments, the sizing member 56 is preferably manufactured from a biologically-compatible material such as, without limitation, elastotner, silicon, or any other material having sufficient resiliency to permit pre-stretching of the annuloplasty ring 44 prior to and during implantation, while having sufficient coinractive force to decrease the size of the valve annulus to a desired diameter. Similarly, the tissue-engaging sheath 58 is preferably manufactured from a biologically-compatible material having comparable resiliency, such as, without limitation, Dacron (polyethylene terepthalate), polyester knit, PTFE knit, and ePTFE knit, and may further incorporate tissue growth enhancing materials. The attachment device 54 may comprise various tissue-engaging devices, including, for example, needles, barbs, or hooks. Those skilled in the art will appreciate the attachment devices 54 is preferably manufactured from a biologically-compatible material such as, without limitation, stainless steel, titanium, or Nickel-Titanium alloy (Nitinol). FIG. 3D shows a perspective view of the annuloplasty ring of the present embodiment having a plurality of attachment devices 54 positioned about the device body 44.

[0035] FIGS. 4A–4C show an alternative embodiment of the present invention which includes size constraining support members. FIG. 4A shows the annuloplasty ring 60 of the present embodiment in a contracted state, wherein the ring 60 comprises a rectilinear segment 62, an arcuate segment 64, and two curved ends 66 and 68 positioned therebetween. The ring 60 is comprised of a series of support members 70 positioned about the device. The support members 70 are positioned immediately adjacent to each other in the contracted state, though it is to be understood that the resilient inner sizing member is biased toward a fully relaxed diameter that is smaller than the diameter in the contracted state. In other words, the plurality of support members 70 constrain contraction of the inner sizing member 72 to a contracted diameter that is larger than the fully relaxed diameter. FIG. 4B shows the ring 60 stretched prior to implantation, having the resilient inner sizing member 72 positioned within the support members 70. As shown in FIG. 4C, each support member 70 has a receiving lumen 74 formed therein which is capable of receiving the inner sizing member 72. The attachment sheath 76 may be positioned on the exterior of the support members 70. Prior to implantation, the ring 60 is pre-stretched to a fully expanded diameter roughly equivalent to the diameter of the dilated valve annulus and the attachment sheath is attached to the tissue using, for example, sutures, staples, or barbs. Once the ring 60 is suitably positioned with the valve annulus and attached thereto, the insertion device (not shown) is removed and the ring 60 contracts causing each size support member 70 to engage the adjacent support members 70, thereby limiting the degree of contraction that the ring 60 may achieve. Again, the plurality of support members 70 constrain contraction of the inner sizing member 72 to a contracted diameter that is smaller than the fully expanded diameter but larger than the fully relaxed diameter.

[0036] The support members 70 are preferably manufactured from a biologically-compatible material such as, without limitation, stainless steel, titanium, or plastic. Like the previous embodiment, the inner sizing member 72 is preferably manufactured from a biologically compatible material such as, without limitation, elastomer, silicon, or any other material having sufficient resiliency to permit pre-stretching of the annuloplasty ring 60 prior to and during implantation, while having sufficient contractive force to decrease the size of the valve annulus to a desired diameter. Similarly, the attachment sheath 76 is preferably manufactured from a resilient biologically-compatible material such as, without limitation, Dacron (polyethylene terepthalate), polyester knit, PTFE knit, and ePTFE knit, or may incorporate tissue growth-enhancing materials.

[0037] The present invention further discloses a method of repairing a dilated or otherwise incompetent annulus. An exemplary open-chest surgical repair of a mitral valve will be disclosed herein. It should be understood the method disclosed herein is not intended to limit the scope of the present invention in any way.

[0038] The mitral valve partially forms the atrio-ventricular junction between the left atrium and left ventricle of the heart and is most easily reached through the wall of the left atrium. Those skilled in the art will appreciate that the wall of the left atrium is may be accessed through a medial sternotomy procedure. To gain access to the mitral valve during the sternotomy, the surgeon rotates the heart to an anterior position, thereby providing access to the left atrium. An incision is made in the left atrium, thereby providing access to the mitral valve and the valve annulus.

[0039] To insert the annuloplasty ring of the present invention, the ring 20 is stretched for positioning on an insertion device. Those skilled in art will appreciate the present invention may be inserted on a plurality of insertion devices know in the art. Additionally, the annuloplasty ring may be positioned on the insertion device at the time of manufacture or immediately prior to implantation. Ideally, the annuloplasty ring should be stretched to a size commensurate with the diameter of the dilated valve annulus. The ring, positioned on the insertion device, is positioned proximate to the valve annulus and attached to surrounding tissue in a plurality of known and accepted manners, including, suturing, stapling, or any other biologically-compatible attachment technique. With the ring sufficiently attached, the insertion device is removed, resulting in the annuloplasty ring contracting to its pre-stretched diameter, thereby rendering the valve competent. Those skilled in the art will appreciate the contractive force of the annuloplasty ring will determine the amount of post-implantation valvular dilation, thereby permitting the surgeon to accurately predict the post-implantation valve diameter.

[0040] While the foregoing describes the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. By way of example but not of limitation, alternative insertion devices, and alternative attachment devices may be used. It will thus be obvious that certain other modifications may be practiced within the scope of the appended claims.