Three-dimensional annuloplasty ring and template

[0001] The present invention relates generally to medical devices and particularly to a tricuspid annuloplasty ring and delivery template.

[0002] In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers: the left and right atria and the left and right ventricles, each provided with its own one-way valve. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid and pulmonary, and are each mounted in an annulus comprising dense fibrous rings attached either directly or indirectly to the atrial and ventricular muscle fibers.

[0003] Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. Diseased heart valves may be categorized as either stenotic, wherein the valve does not open sufficiently to allow adequate forward flow of blood through the valve, and/or incompetent, wherein the valve does not close completely, causing excessive backward flow of blood through the valve when the valve is closed. Valve disease can be severely debilitating and even fatal if left untreated.

[0004] Various surgical techniques may be used to repair a diseased or damaged valve. In a valve replacement operation, the damaged leaflets are excised and the annulus sculpted to receive a replacement valve.

[0005] Another less drastic method for treating defective valves is through repair or reconstruction, which is typically used on minimally calcified valves. One repair technique that has been shown to be effective in treating incompetence is annuloplasty, in which the effective size of the valve annulus is contracted by attaching a prosthetic annuloplasty repair segment or ring to an interior wall of the heart around the valve annulus. The annuloplasty ring is designed to support the functional changes that occur during the cardiac cycle: maintaining coaptation and valve integrity to prevent reverse flow while permitting good hemodynamics during forward flow. The annuloplasty ring typically comprises an inner substrate of a metal such as stainless or titanium, or a flexible material such as silicone rubber or Dacron cordage, covered with a biocompatible fabric or cloth to allow the ring to be sutured to the heart tissue. Annuloplasty rings may be stiff or flexible, may be split or continuous, and may have a variety of shapes, including circular, D-shaped, C-shaped, or kidney-shaped. Examples are seen in U.S. Pat. Nos. 5,041,130, 5,104,407, 5,201,880, 5,258,021, 5,607,471 and, 6,187,040 B1. Most annuloplasty rings are formed in a plane, with some D-shaped rings being bowed along their anterior or straight side to conform to the annulus at that location.

[0006] The present application has particular relevance to the repair of tricuspid valve, which regulates blood flow between the right atrium (RA) and right ventricle (RV), although certain aspects may apply to repair of other of the heart valves.

[0007] The tricuspid valve 20 is seen in plan view in FIG. 1 and includes an annulus 22 and three leaflets 24a, 24b, 24c (septal, anterior, and posterior, respectively) extending inward into the flow orifice defined by the annulus. Chordae tendineae 26 connect the leaflets to papillary muscles located in the RV to control the movement of the leaflets. The tricuspid annulus 22 is an ovoid-shaped fibrous ring at the base of the valve that is less prominent than the mitral annulus, but slightly larger in circumference. The septal leaflet 24a is the site of attachment to the fibrous trigone, the fibrous “skeletal” structure within the heart. The triangle of Koch 30 and tendon of Todaro 32 provide anatomic landmarks during tricuspid valve repair procedures. The atrioventricular (AV) node 34 is a section of nodal tissue that delays cardiac impulses from the sinoatrial node to allow the atria to contract and empty their contents first, and relays cardiac impulses to the atrioventricular bundle. In a normal heart rhythm, the sinoatrial node generates an electrical impulse that travels through the right and left atrial muscles producing electrical changes which is represented on the electrocardiogram (ECG) by the p-wave. The electrical impulse then continue to travel through the specialized tissue of the AV node 34, which conducts electricity at a slower pace. This will create a pause (PR interval) before the ventricles are stimulated. Of course, surgeons must avoid placing sutures too close to or within the AV node 34. C-rings are good choices for tricuspid valve repairs because they allow surgeons to position the break in the ring adjacent the AV node 34, thus avoiding the need for suturing at that location.

[0008] Despite numerous designs presently available or proposed in the past, there is a need for a tricuspid ring that more closely conforms to the actual shape of the tricuspid annulus.

[0009] The present invention provides an annuloplasty ring including a ring body generally arranged about an axis and being discontinuous so as to define two free ends. The ring body has a relaxed configuration following a three-dimensional path such that the free ends are axially offset from an annulus reference plane through a midpoint of the ring body. In a preferred embodiment, the two free ends are axially offset between about 2-15 mm. The annuloplasty ring is particularly adapted to reinforce the tricuspid annulus, and as such has a curvilinear anterior side ending in one of the free ends, a curvilinear posterior side ending in the other of the free ends, and a relatively straight septal side extending between the anterior and posterior sides. The posterior side is shorter and has a smaller radius of curvature than the anterior side.

[0010] In accordance with one aspect of the present invention, the ring body comprises an inner structural support of multiple bands of elastic material. A low friction material may be interposed between each two adjacent bands to facilitate movement therebetween. The multiple bands may be embedded in a matrix of pliable material, preferably molded silicone. In one embodiment, there are two concentrically disposed bands embedded in the matrix of pliable material. To facilitate bending about axes that extend radially, each of the multiple bands of elastic material may have a relatively wider radial dimension than its axial dimension.

[0011] Another aspect of the invention is an annuloplasty ring that comprises a three-dimensional ring body generally arranged about a central axis and being discontinuous so as to define two free ends, wherein the ring body has a construction that renders it more flexible in bending at the two free ends than in a midpoint thereof.

[0012] The annuloplasty ring body may comprise an inner structural support having two free ends, a curvilinear anterior side ending in one of the free ends, a relatively straight septal side ending in the other of the free ends, and a curvilinear posterior side extending between the anterior and septal sides, wherein a majority of the posterior side lies generally in a plane perpendicular to the axis. The two free ends are desirably both axially offset in the same direction from the plane. Also, the structural support may have a cross-section that changes around its length. For example, the the cross-section may be partly C-shaped in the posterior side, yet the two free ends are rectangular.

[0013] In accordance with a further aspect of the invention, the ring body may comprise an inner structural support band surrounded by a pliable matrix, wherein the matrix includes a tubular inner portion that surrounds the band and an outer flange through which implantation sutures can pass. The outer flange may be curved so as to be convex on its outer surface. Preferably, the outer flange is connected to the inner tubular portion with a plurality of circumferentially spaced apart radial walls so as to create a celled structure.

[0014] A further aspect of the present invention provides an annuloplasty ring including a ring body generally arranged about the central axis and being discontinuous so as to define two free ends. The ring body has a construction that renders it more flexible in bending about axes that extend radially from the central axis than about the central axis itself. The ring body may comprise an inner structural support of multiple bands of elastic material. A low friction material may be interposed between each two adjacent bands. The multiple bands may be embedded a matrix of pliable material, preferably silicone. There may be two concentrically disposed bands embedded in the matrix of pliable material. Desirably, each of the multiple bands elastic material has a relatively wider radial dimension than its axial dimension.

[0015] In a still further aspect of the present invention, an annuloplasty ring template is provided. The template has a rigid body with a peripheral mounting ring generally arranged about an axis and being discontinuous so as to define two free ends. The mounting ring follows a three-dimensional path such that the free ends are axially offset. The template may include a central platform to which the peripheral mounting ring is connected via a plurality of generally radially extending spokes. A handle-receiving hub may extend generally away from central platform. Desirably, the peripheral mounting ring extends about three-quarters circumferentially about the axis.

[0016] In a preferred embodiment, the peripheral mounting ring of the template defines a radially outward groove therein for receiving an annuloplasty ring. The template further may include a plurality of cutting guides provided on the peripheral mounting ring. A pair of through holes in the mounting ring are provided on either side of each cutting guide such that a length of suture may extend through or about an annuloplasty ring positioned on the outside of the mounting ring, through one of the holes, over the cutting guide, through the other hole, and back into the annuloplasty ring. Each cutting guide may comprise a pair of intersecting slots, one of the slots being shallower than the other and positioned to receive a suture extending between the through holes. The deeper slot provides space into which a sharp instrument may extend to sever the suture at the cutting guide.

[0017] Further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.

[0030] The present invention provides a non-planar or three-dimensional (3D) annuloplasty ring that is shaped to conform to a 3D annulus. Some studies show that the tricuspid valve has such a non-planar annulus, and thus the present invention is particularly suited for repair of that valve. Of course, other valves may in some patients have 3D annuluses, and the annuloplasty ring of the present invention may also have use in those locations, if desired by the surgeon. Of course, all annuloplasty rings are three-dimensional to some extent, as they have a cross-sectional thickness. In the context of the present invention, a non-planar or three-dimensional annuloplasty ring has a nominal cross-sectional centerline that assumes a three-dimensional shape, or in other words does not lie in a single plane. Likewise, the exemplary ring of the present invention, as well as other shapes that may benefit from the features embodied herein, has a non-circular peripheral shape, but is shown having an axis. The term “axis” in reference to the illustrated ring, and other non-circular or non-planar rings, refers the line through the ring that passes through the area centroid of the ring when viewed in plan view. This “axis” can also be viewed as imaginary line of blood flow within the valve orifice and thus within the ring when implanted therein.

[0031] It should be understood that the various constructional details of any one embodiment herein may be transferred to another embodiment, even if not explicitly mentioned. For instance, the inner ring structural support seen in FIGS. 8A-8D may be used in a ring that has a silicone sleeve and outer fabric covering as described elsewhere. Also, the templates 90 or 110 seen in FIGS. 5-7 may be adapted to conform to and hold the ring constructed using the inner ring structural support seen in FIGS. 8A-8D.

[0032] Despite numerous ring designs in the past, none has effectively accommodated the shape of the tricuspid valve. Prior C-shaped rings (i.e., those with a break in continuity around the periphery) are formed in a plane. When implanted, a planar ring will tend to conform a non-planar annulus to its own shape because of its relative stiffness. Unfortunately, this may interfere with optimum performance of the “repaired” valve.

[0033] FIG. 2 illustrates an exemplary annuloplasty ring 40 of the present invention having a ring body 42 generally arranged about an axis 44 and being discontinuous so as to define two free ends 46a, 46b. FIG. 3 shows a tricuspid valve 20 in perspective, and FIG. 4 shows the annuloplasty ring 40 in plan view after having been implanted or otherwise affixed to the tricuspid valve 20. When viewed in plan view, as seen in FIG. 4, the body 42 of the annuloplasty ring 40 defines a relatively straight septal side 50a, a curvilinear posterior side 50b, and a curvilinear anterior side 50c. The posterior side 50b is shorter and has a smaller radius of curvature than the anterior side 50c.

[0034] Again, the axis 44 in FIG. 2 lies at the centroid of the ring or along of the axis of blood flow through the ring 40 when implanted, and it will be understood that the directions up and down are as viewed in the figure. The ring 40 is designed to be implanted in a tricuspid annulus such that blood will flow in the downward direction.

[0035] FIG. 2 illustrates an exemplary axial offset of the two free ends 46a, 46b. Radial lines are shown from each free end 46a, 46b to the central axis 44. The distance A between the intersections of these radial lines and the axis 44 represents the axial offset. The distance A may vary depending on the patient, but is typically between about 2.0 mm and 15.0 mm. In this embodiment, the curvilinear anterior side 50c lies generally in a plane all the way to the free end 46a. Therefore, because the second free end 46b drops below the main part of the anterior side 50c, which generally defines an annulus reference plane for the ring and host annulus, then it is axially offset from the first free end 46a. However, the first free end 46a may not lie in the annulus reference plane, and may drop to the same elevation as the second free end 46b. Either free end 46a, 46b may even be axially above the annulus reference plane. In short, the ring 40 is designed to be three-dimensional to conform to the native tricuspid annulus, and those of skill in the art will recognize the number of possible permutations.

[0036] Although the annuloplasty ring 40 may be constructed in a number of ways as defined in the prior art, one particularly useful construction includes some relatively rigid yet elastic inner structural support surrounded by a pliable core material and a fabric cover. For example, as seen in FIG. 2A, the annuloplasty ring 40 may include an inner skeleton of multiple bands 60 of relatively rigid yet elastic material such as Elgiloy surrounded by a suture-permeable core material 62 such as silicone, and having an outer fabric cover 64. The multiple bands 60 may be separated by plastic or other relatively low friction material (e.g., TEFLON) so as to be able to more easily flex with respect to one another. It will be noted by those of skill in the art that the multiple bands 60, which limit the flexibility of the ring 40, are aligned generally perpendicular to the axis 44 and thus the ring is least flexible in bending about the axis. Desirably, the ring 40 of the present invention is more flexible in bending about axes along radial lines from the central axis 44. That is, for example, the free ends 46a, 46b are more easily flexed up and down parallel to the axis than toward or away from one another. There are a number of ways to accomplish this flexibility orientation, as seen in FIGS. 2C-2E.

[0037] In contrast, FIG. 2B shows a cross-section of a ring 70 of the prior art that has an inner skeleton of multiple bands 72 of relatively rigid material such as Elgiloy surrounded by a suture-permeable core material 74 such as silicone, with an outer fabric cover 76. In such prior devices, the bands 60 are oriented along or parallel to the axis 44, and thus are more flexible in bending about the central axis.

[0038] FIG. 2C shows a cross-section of an alternative ring of the present invention having a plurality of inner bands 78 embedded in a more pliable matrix 80 such as silicone. As before, the bands 78 are desirably more rigid than the matrix 80 and provide structural support to the annulus when implanted. The bands 78 are thin in the axial dimension, and wide in the radial direction, so as to provide the preferred flexibility characteristics of the ring of the present invention. The bands 78 are shown spaced apart with matrix 80 material therebetween to enhance the aforementioned flexibility.

[0039] FIG. 2D illustrates a further embodiment in which there are two concentrically disposed structural bands 81 embedded in a matrix 82 of pliable material. The bands 81 together create the desired flexibility characteristics of the ring, as explained above, even if their respective cross-sections are square or circular. As seen, however, the bands 81 preferably have a larger radial than axial dimension which contributes to the flexibility of the ring about radial axes.

[0040] FIG. 2E shows a cross-section of a ring having a circular reinforcing band 83 surrounded by a pliable matrix 84. A tubular inner portion of the matrix 84 surrounds the band 83, while an outer wall or flange 85 provides additional material through which implantation sutures can pass. In a preferred embodiment, the flange 85 is curved so as to be convex on its outer surface, and is connected to the inner tubular portion with a plurality of circumferentially spaced apart radial walls 86. A series of circumferential cells 87 is thus created between the walls 86. The celled structure of the matrix 84 renders it soft and compressible, which facilitates conformance of the ring to very uneven annuluses. A fabric covering (not shown) may also be used.

[0041] With reference again to FIGS. 2 and 3, the three-dimensional shape of the annuloplasty ring 40 is seen corresponding generally to the shape of the tricuspid annulus 22. The first free end 46a registers with an area adjacent the septal leaflet 24a, to the anterior side of the AV node 34. The second free end 46b registers with an area adjacent the septal leaflet 24a, but to the posterior side of the AV node 34. The second free end 46b is axially offset with respect to the first free end 46a as is the respective anatomical attachment areas. Therefore, the annuloplasty ring 40 closely conforms to the 3-D shape of the annulus 22, and minimal distortion of the tissue occurs when attaching the ring thereto. Furthermore, the oriented flexibility of the ring 40 facilitates the 3-D shape matching, between ring and tissue because the free ends 46a, 46b may be easily flexed with respect to one another along arcs that are generally parallel to the axis 44.

[0042] The annuloplasty ring 40 is seen in FIG. 4 implanted in the annulus 22 using a plurality of sutures 88, although those of skill in the art will understand that there are other attachment means. The sutures 88 are evenly distributed around the ring body 42 and tied off to present minimal surface roughness and reduce the chance of thrombi forming thereon. Again, the free ends 46a, 46b are shown on either side of the AV node 34, which minimizes the risk of damaging the sensitive conduction system.

[0043] A preferred delivery template and method are also provided for the three-dimensional annuloplasty ring 40 of the present invention. With reference to FIGS. 5 and 6, the ring 40 is shown releasably secured to a template 90 that is in turn held at the distal end of a delivery handle 92. The template 90 provides a suturing platform for the ring 40, maintaining its advantageous shape while being implanted. In this regard, the template 90 includes a peripheral mounting ring 94 generally arranged about an axis coincident with the axis 44 of the ring 40. The peripheral mounting ring 94 is discontinuous so as to define two free ends 96a, 96b and generally follows a three-dimensional path such that the free ends are axially offset. Desirably, the three-dimensional path of the peripheral mounting ring 94 is the same as that of the annuloplasty ring 40. Sutures (not shown) or other similar expedient releasably secure the ring 40 to the template 90 to form the assembly seen in FIG. 5. A hub 98 of the handle 92 may be releasably attached to the template using sutures or quick-release clips or the like so that the handle may be removed during implantation for better visibility of the annulus.

[0044] FIG. 6 shows a step in an interrupted suture implant procedure. After exposing the annulus 22, the surgeon secures a plurality of individual sutures 100 around the annulus 22 in the locations that the sutures will be arranged around the ring 40. The free ends of each suture 100 are then passed through the corresponding positions in the suture-permeable outer portion of the ring 40, as seen at 102. After all of the sutures 100 have been pre-threaded through the ring 40, the surgeon manipulates the ring using the handle 92 down the array of sutures and into position in the annulus 22. The next steps that are not illustrated include severing each suture close to the ring 40 and tying them off as seen in FIG. 4. Again, the handle 92 may be detached from the template 90 for this operation. Finally, the template 90 is detached from the ring 40 and removed with any attaching sutures from the operating site.

[0045] FIGS. 7A-7C are several perspective views of an exemplary template 110 for use in implanting the ring 40 of the present invention. The template 110 includes a peripheral mounting ring 112 connected to a central platform 114 via a plurality of spokes 116. The template 110 may be constructed of a variety of materials, with a biocompatible plastic being preferred. Windows 117 exist between the spokes 116 for greater visibility of the implant site. A handle-receiving hub 18 projects upward from the platform 114 and generally defines a central axis 120 of the template 110. The mounting ring 112 extends approximately three-quarters around the axis 120 and terminates in two axially-spaced free ends 122a, 122b.

[0046] In a preferred embodiment, the mounting ring 112 includes a radially outwardly opening channel or groove 124, which is sized to have about the same curvature as the ring 40, and thus snugly retains the ring 40 in place around the template 90. The groove 124 is shallow so that a majority of the ring projects outward therefrom to facilitate exposure to the annulus and attachment thereto.

[0047] A plurality, preferably three, of cutting guides 126 projects axially upward from the mounting ring 112 at regular intervals around its periphery. The cutting guides 126 each include a first relatively deep slot 128 and a second shallower slot 130 crossing the first slot. Sutures (not shown) desirably fasten the ring 40 to the template, and extend across the cutting guides 126 for easy severability. A plurality of passages 132 in the mounting ring 112 opening in the groove 124 permit passage of sutures directly from the ring body 42 through the mounting ring to the cutting guides 126. As seen best in FIG. 7A, there are two such passages 132 on either side of each cutting guide 126. The passages 132 are desirably straight holes from the upper surface of the mounting ring 112 that intersect and thus open to the concave groove 124.

[0048] The overall shape of the mounting ring 112 is three-dimensional, as explained above, with the two free ends 122a, 122b being axially spaced apart. The three-dimensional may be a gentle spiral, or other similar shape as dictated by the particular patient, or by a representative sample of patients. In the illustrated embodiment, and as best seen in FIG. 7C, a majority of the mounting ring 112 lies in a plane, with one side that terminates in the second free end 122b being formed in a gentle curve or spiral so as to be axially spaced from the first free end 122a. The annuloplasty ring is arranged on the mounting ring 112 so that the portion that will lie adjacent the septal leaflet (see 24a and 50a in FIG. 4) extends along the spiral segment of the mounting ring. In general, it is believed that many patients have a relatively planar tricuspid annulus around the anterior and posterior sides, but a depressed septal side. The shape of the mounting ring 112 thus mimics the presumed anatomical contour, and thus the ring can be sewn into place without unduly distorting the annulus.

[0049] FIGS. 8A-8D illustrate an exemplary inner structural support 150 for a tricuspid annuloplasty ring of the present invention. The structural support 150 is ultimately is covered with one or more outer flexible layers as described above, and therefore the final ring body assumes the shape of the support. The structural support 150 may be made of a relatively rigid material yet elastic material such as Elgiloy.

[0050] When viewed in plan view, as seen in FIG. 8B, the structural support 150 defines a relatively straight septal side 156a ending in one of the free ends 154b, a curvilinear posterior side 156b, and a curvilinear anterior side 156c ending in the other of the free ends 154a. The posterior side 156b is between the other two sides. As in the earlier embodiment, the posterior side 156b is shorter and has a smaller radius of curvature than the anterior side 156c.

[0051] The structural support 150 is generally arranged about an axis 152 and is discontinuous so as to define two free ends 154a, 154b. A majority of the structural support 150 is located generally in an annulus reference plane 151 (see FIG. 8D) perpendicular to the axis 152, and the two free ends 154a, 154b curve away from the plane so as to be offset therefrom. The annulus reference plane 151 is defined as the plane that is perpendicular to the axis 152 at the elevation of the tricuspid annulus. That elevation, in turn, is represented in the drawings by the midpoint of the anterior side 156c, or at least the midpoint of the larger cross-section portion thereof (as detailed below). FIG. 8C illustrates a midpoint M in the anterior side 56c that represents the nominal elevation of the host annulus. A perpendicular line to the axis 152 intersects reference point R. The reference plane is thus perpendicular to the axis 52 through point R.

[0052] As seen best in FIG. 8D, the two free ends 154a, 154b are thus axially offset from the reference plane 151 in the same direction, as well as each other. Of course, the free ends 154a, 154b need not be axially offset from each other as is shown, though the ring will still be three-dimensional (that is, the ring is non-planar). For instance, one or both of the free ends 154a, 154b may even curve upward above the reference plane 151. The particular three-dimensional configuration is modeled to fit the natural shape of a tricuspid annulus, or at least to approximate that shape as best as possible, and thus those with an understanding of the tricuspid annulus will realize that a variety of shapes are possible.

[0053] With regard to FIGS. 8B and 9A-9C, the cross-sectional shape of the structural support 150, at least along most of the anterior side 156c, is designed so as to have more flexible in bending at the free ends 154a, 154b. FIG. 9A is a cross-section through the anterior side 156c and shows a generally C-shaped cross-section with an outwardly-facing groove 160 formed between an upper web 162 and a lower web 164, both extending from an inner base portion 166. The upper web 162 extends slightly farther radially outward than the lower web 164.

[0054] The cross-sectional shape of the structural support 150 changes along its length, from the midpoint M to the free ends 154a, 154b. The transition between the cross-section at the middle of the anterior side 156c and the cross-sections at the two free ends 154a, 154b is gradual, and is reflected in FIGS. 9A-9C. The webs 162, 164 gradually diminish in radial dimension until all that is left is the rectangular base portion 166, as seen in FIG. 9C. Because at both free ends 154a, 154b the radial dimension is smaller than the axial, the ends are more flexible in bending about the central axis 152. It should be mentioned that the properties of the inner ring structural support seen in FIGS. 8A-8D may be attained with other structures, for example, with the multiple concentric bands as described above.

[0055] While the foregoing is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Moreover, it will be obvious that certain other modifications may be practiced within the scope of the appended claims.