Abstract:
This invention relates to a system used to fashion, size, and implant a tissue annuloplasty band. This system comprises (1) a device to cut tissue; (2) a device to fashion (i.e., roll, fold, bunch, etc.) the tissue into a band (i.e., the tissue annuloplasty band); and (3) a sizer that comprises an mounting ring which allows for determining and maintaining the proper size and shape of the tissue annuloplasty band while it is attached to the annulus of a heart valve. These components can be used alone, together as a system, or in any combination to fashion, size, and/or implant the tissue annuloplasty band.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 60/176,046, filed Jan. 14, 2000 by John R. Liddicoat et al. for INSTRUMENTS AND METHODS TO FASHION, SIZE, AND IMPLANT A TISSUE ANNULOPLASTY DEVICE, which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the correction of valvular heart disease. In particular, it relates to the fashioning, sizing and implanting of tissue as an annuloplasty band or ring to be used for the correction of valvular heart disease. 
     BACKGROUND OF THE INVENTION 
     The human heart comprises four heart valves. Two of these valves are located between the left and right atria and ventricles and are called the mitral and tricuspid valves, respectively. These valves serve to maintain one-way blood flow into the ventricles and to prevent the regurgitation of blood back into the atria. Although the present invention can be used for many different applications including mitral and tricuspid valve repair, for the purposes of example it will hereinafter be described in connection with the repair of a mitral valve. 
     Mitral valve repair is the surgical procedure of choice to correct mitral regurgitation of all etiologies. With the use of current surgical techniques, approximately 70 to 95% of all regurgitant mitral valves can be repaired. The advantages of mitral valve repair over mitral valve replacement are well documented. These advantages include better preservation of cardiac function and reduced risk of anticoagulant-related hemorrhage, thromboembolism and endocarditis. 
     Nearly all mitral valve repairs include an annuloplasty. The annuloplasty consists of implanting a prosthetic band or ring that surrounds all or part of the circumference of the annulus of the valve. The annuloplasty serves several functions: it remodels the annulus, decreases tension on suture lines, increases leaflet coaptation, and prevents recurrent annular dilation. In addition, the annuloplasty improves repair durability. 
     The placement of a prosthetic annuloplasty band or ring in the heart results in a risk of thromboembolism and infection; these risks are unavoidable and persist for the life of the patient. Formation of blood clots on prosthetic materials in the heart often results in stroke, and infection of a prosthetic annuloplasty band or ring may lead to life-threatening sepsis and the need for urgent re-operation. 
     The ideal annuloplasty would be effected using a universally flexible, autologous material. Such a material does in fact exist, in the form of the patient&#39;s own pericardium. The pericardium is the sac in which the heart sits. The pericardium is often used by heart surgeons to repair congenital heart defects. It heals well, and almost never becomes infected. However, the pericardium can be difficult to work with. 
     In order to make practical use of autologous pericardium for a mitral valve annuloplasty, the surgeon would need apparatus to facilitate the creation of a tissue annuloplasty band or ring of the appropriate length and thickness, and to ensure that the tissue annuloplasty band or ring will maintain the chosen dimensions while it is applied to the heart. 
     The development of a system for constructing and deploying a pericardial annuloplasty band or ring would have great benefit for the patient. No prosthetic material would be placed in the heart, greatly reducing the risk of thromboembolism and infection. No anticoagulation would be necessary. In addition, pericardium remains flexible as it heals, and this would result in preserved mitral valve physiology. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a pericardial annuloplasty band. 
     Another object of the present invention is to provide apparatus and methods that facilitate the construction of a precisely measured annuloplasty band from the patient&#39;s own pericardium. 
     Still another object of the present invention is to provide a template upon which the fashioned tissue annuloplasty band is mounted, facilitating sizing and placement of the tissue annuloplasty band in the heart and ensuring that the tissue annuloplasty band maintains its shape during application. 
     These and other objects are addressed by the present invention which comprises a tissue annuloplasty band and apparatus and methods for fashioning, sizing and implanting the same. In one preferred form of the present invention, the graft tissue is first cut to an appropriate size. Then the cut tissue is fashioned into the appropriate shape, i.e., an elongated length. If desired, an internal or external support structure may be provided to help support and/or manipulate the elongated length of tissue. Next, the elongated length of tissue is mounted onto an adjustable mounting ring so as to form a tissue annuloplasty band. Then the appropriate size and shape of the tissue annuloplasty band is determined. This is done by directly measuring the mitral valve, or by placing the tissue annuloplasty band (which is mounted on the adjustable mounting ring) in the left atrium and visually comparing it against the patient&#39;s mitral valve. The size of the tissue annuloplasty band is then adjusted, by adjusting the size of the adjustable mounting ring, until the tissue annuloplasty band is the appropriate size. Any excess tissue is marked for later excision. Next, sutures are placed through the patient&#39;s annulus and through the tissue annuloplasty band, which is still seated on the adjustable mounting ring. The tissue annuloplasty band is then guided into place with the assistance of the adjustable mounting ring. Then the tissue annuloplasty band is tied down into place, while the tissue annuloplasty band is still mounted onto the adjustable mounting ring, so as to maintain its shape and length during final seating. Once the tissue annuloplasty band has been tied into place, the tissue annuloplasty band is dismounted from the adjustable mounting ring. The adjustable mounting ring is then removed, and any excess tissue previously marked is excised. 
     In another preferred form of the invention, the adjustable mounting ring may be replaced by a set of pre-sized mounting rings. In this case, an appropriate one of the pre-sized mounting rings is selected by directly measuring the mitral valve or by placing different pre-sized mounting rings in the left atrium and visually comparing them against the patient&#39;s mitral valve. Once the appropriate pre-sized mounting ring has been selected, the elongated length of graft tissue is mounted onto the pre-sized mounting ring and then the remainder of the annuloplasty is performed in the manner described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be further disclosed in the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
         FIG. 1  is a schematic view of a male/female cutting die used in one preferred form of the invention; 
         FIG. 2  is a schematic view showing graft tissue being rolled into the tissue annuloplasty band while on the male cutting die; 
         FIG. 3  is a schematic view showing a first sizer formed in accordance with the present invention, with the first sizer&#39;s handle extending perpendicular to the plane of the sizer&#39;s adjustable mounting ring; 
         FIG. 4  is a view like that of  FIG. 3 , except showing the rear side of the first sizer shown in  FIG. 3 ; 
         FIG. 5  is a schematic view of the distal end of the first sizer, with the adjustable mounting ring being shown in its largest diameter configuration; 
         FIG. 6  is a schematic view of the distal end of the first sizer, with the adjustable mounting ring being shown in its smallest diameter configuration; 
         FIG. 7  is a schematic end view of the distal end of the first sizer, with the adjustable mounting ring being shown in its smallest diameter configuration; 
         FIG. 8  is a schematic view showing a second sizer formed in accordance with the present invention, with the second sizer&#39;s handle extending parallel to the plane of the sizer&#39;s adjustable mounting ring; 
         FIG. 9  is a schematic view of the distal end of the second sizer, with the adjustable mounting ring being shown in its largest diameter configuration; 
         FIG. 10  is a schematic side view of the distal end of the second sizer, with the adjustable mounting ring being shown in its largest diameter configuration; 
         FIG. 11  is a schematic view of the distal end of the second sizer, with the adjustable mounting ring being shown in its smallest diameter configuration; 
         FIG. 12  is a schematic view showing the tissue annuloplasty ring mounted on the second sizer&#39;s adjustable mounting ring; 
         FIG. 13  is a schematic view showing a set of third sizers, wherein each of the third sizers comprises a pre-sized mounting ring; 
         FIG. 14  is a schematic view showing manual sizing of the graft tissue used for the tissue annuloplasty band; 
         FIG. 15  is a schematic view of a guide tube used to help guide the graft tissue through an external mesh; 
         FIG. 16  is a schematic view showing the external mesh, guide tube and tissue hook; 
         FIG. 17  is a schematic view showing the graft tissue prior to being drawn into the guide tube; 
         FIG. 18  is a schematic view showing the graft tissue after it has been drawn into the guide tube; 
         FIG. 19  is a schematic view showing the guide tube being removed and the tissue being cut to fit the external mesh; 
         FIG. 20  is a schematic view showing the tissue secured within the external mesh and after synching the end purse-string sutures closed, forming the tissue annuloplasty band; 
         FIG. 21  is a schematic view showing the tissue annuloplasty band being attached to a pre-sized (i.e., fixed-diameter) mounting ring; and 
         FIG. 22  is a schematic view showing the tissue annuloplasty band attached to a pre-sized, fixed-diameter mounting ring. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This invention relates to the rapid fashioning, sizing, and implanting of a tissue annuloplasty band for the general purpose of cardiac valve repair. Although the description provided herein describes the use of the system for mitral valve repair, the apparatus and method may be used for other applications as well. Therefore, the following description is intended merely as an example of how the apparatus and method of the present invention may be used, and not by way of limitation. 
     In accordance with the present invention, the graft tissue (i.e., pericardium, vein, or other autologous or non-autologous tissue) is first cut to an appropriate size. This may be done with any appropriate cutting tool. Preferably, however, a male/female cutting die is used to cut the tissue into the general size and shape appropriate to create the tissue annuloplasty band. 
     More particularly, and looking now at  FIG. 1 , there is shown a male/female cutting die  10 . Cutting die  10  comprises a male die  20  having a groove  30  formed therein, and a female die  40  having a window  50  formed therein. When a piece of donor tissue (e.g., pericardium) is placed between male die  20  and female die  40 , and the two die members are thereafter brought together, a piece of graft tissue (corresponding in size to window  50  in female die  40 ) will be cut from the donor tissue. 
     Once the graft tissue has been cut to an appropriate size, it is then fashioned into the appropriate shape, i.e., an elongated length. This may be done by rolling, folding, bunching, etc. 
     In one preferred form of the invention, the tissue is rolled about an axle using the male die as the base. More particularly, and looking now at  FIG. 2 , after a piece of graft tissue  60  has been cut, and while graft tissue  60  is lying on male die  20 , an axle  70  is pressed down into groove  30 . Then one tissue end  80  is folded over the other tissue end  90 , and axle  70  is rolled, so as to form a tissue annuloplasty band  100 . If desired, an adhesive, a sealant, a medication or the like may be applied to the tissue. By way of example, an adhesive might be applied to a final rolled edge so as to keep the tissue annuloplasty band from unrolling. Axle  70  is made of a relatively flexible material such as pliable plastic or metal. The body of the axle, while being flexible, may or may not stretch along its linear axis. The two ends  110 A,  110 B of axle  70  preferably have elastic properties, allowing these portions of the axle to stretch along their linear axis. 
     Once the graft tissue has been rolled into tissue annuloplasty band  100 , it is mounted onto a mounting ring for sizing and implanting. This may be implemented in a variety of ways, using a variety of devices. 
     In one preferred form of the invention, and looking now at  FIGS. 3-7 , a first sizer  120  is used. First sizer  120  comprises a handle  130  and an adjustable mounting ring  140 . Handle  130  preferably comprises two cylinders  150 ,  160  which are able to move relative to one another. Cylinder  150  is connected to mounting ring  140  by a drive cable  170  (shown in phantom). Drive cable  170  is in turn connected to a central bevel gear  180  ( FIG. 7 ) in adjustable mounting ring  140 . Rotation of central bevel gear  180  in turn causes the additional bevel gears  190  to rotate. These bevel gears  190  are coupled to threaded shafts  200 . Adjustable mounting ring segments  210  are internally threaded and ride on the threaded shafts  200 . The rotation of threaded shafts  200  causes mounting ring segments  210  to move radially and hence causes adjustable mounting ring  140  to expand and contract (i.e., to change in radial dimension). Accordingly, it will be seen that rotation of cylinder  150  relative to cylinder  160  results in a change in the geometry (i.e., the size) of adjustable mounting ring  140 . Cylinder  160  (i.e., the one that is not connected to adjustable mounting ring  140  by drive cable  170 ) serves as the support portion of the handle and remains in a relatively fixed orientation with respect to adjustable mounting ring  140 . Cylinder  160  may have a constant outer diameter or, alternatively, it may have a stepped outer diameter such as that shown in  FIGS. 3 and 4 . Handle  130  also has a size indicator  220  on the outside of cylinder  160  that shows the size of the tissue annuloplasty band after it has been properly sized. 
     As mentioned above, adjustable mounting ring  140  is (i) connected to cylinder  150  by drive cable  170 , and (ii) fixed to cylinder  160 . Adjustable mounting ring  140  comprises a central body  230  that contains the aforementioned bevel gears  180  and  190 . These gears  180  and  190  are in turn coupled to the mounting ring segments  210  to which the tissue annuloplasty band  100  will be attached. These mounting ring segments  210  are attached to central body  230  by the threaded shafts  200 . Accordingly, movement of the aforementioned bevel gear  180  via cable  170  causes the mounting ring segments  210  to expand and contract relative to central body  230 . Hence, the tissue annuloplasty band  100  can be adjusted to the appropriate size for varying patient anatomies. Mounting ring segments  210  can have additional support, e.g., by lateral stays  240  interacting with each other. The outer edge  250  of each segment  210  preferably has a groove  260  in which the tissue annuloplasty band  100  is mounted. 
     With the aforementioned first sizer  120 , the sizer&#39;s handle  130  extends perpendicular to the plane of the sizer&#39;s adjustable mounting ring  140 . Alternatively, and looking now at  FIGS. 8-11 , there is shown a second sizer  120 A in which the sizer&#39;s handle  130  extends parallel to the plane of the sizer&#39;s adjustable mounting ring  140 . 
     The tissue annuloplasty band  100  ( FIG. 2 ) is placed into groove  260  on adjustable mounting ring  140  (FIG.  12 ). Then the elastic ends  110 A,  110 B of axle  70  are attached to one another. This creates tension on the tissue, which keeps the tissue annuloplasty band  100  in the groove  260  on the mounting ring. Clamps, ties or sutures can be applied as necessary for increased stability. 
     Next, the appropriate size and shape of the tissue annuloplasty band  100  is determined. To do this, the tissue annuloplasty band  100 , which is now mounted on adjustable mounting ring  140 , is placed in the patient&#39;s left atrium and visually compared to the patient&#39;s mitral valve. Alternatively, the mitral valve may be measured directly. The surgeon then adjusts the size of tissue annuloplasty band  100  by turning cylinder  150  of handle  130  until tissue annuloplasty band  100  is appropriately sized. Any excess tissue is marked for later excision. 
     Next, sutures are placed through the patient&#39;s annulus and subsequently through the tissue annuloplasty band  100 . The tissue annuloplasty band  100  is then guided into place with the assistance of sizer  120  (or  120 A). Tissue annuloplasty band  100  is then tied down into place, while it is still mounted on adjustable mounting ring  140 , so as to maintain its shape during final seating. Once tissue annuloplasty band  100  has been tied into place, the elastic ends  110 A,  110 B of axle  70  are detached from one another. Any other stabilizing components such as clamps, ties, or sutures that aided in mounting tissue annuloplasty band  100  to adjustable mounting ring  140  are detached. Adjustable mounting ring  140  is then removed, and axle  70  is withdrawn. Any excess tissue previously marked is excised. 
     If desired, sizer  120  ( 120 A) can be constructed so that handle  130  may be detached from adjustable mounting ring  140 . With such a construction, handle  130  may be removed after guiding tissue annuloplasty band  100  to the surgical site, but before the band is removed from adjustable mounting ring  140 . 
     It is also possible to practice the present invention using a pre-sized, fixed diameter mounting ring. More particularly, and looking now at  FIG. 13 , there is shown a set of third sizers  120 B, wherein each of the third sizers  120 B comprises a pre-sized, fixed diameter mounting ring  140 B (preferably having a peripheral groove  260 B) and an associated handle  130 B. Each mounting ring  140 B may comprise a complete circle (e.g., as shown in  FIG. 13 ) or only a portion of a circle (e.g., as shown in FIG.  22 ). In this form of the invention, an appropriate one of the pre-sized mounting rings  140 B is selected by directly measuring the mitral valve or by placing different pre-sized mounting rings in the left atrium and visually comparing them against the patient&#39;s mitral valve. Once the appropriate pre-sized mounting ring  140 B has been selected, tissue annuloplasty band  100  ( FIG. 2 ) is mounted onto the pre-sized mounting ring  140 B, i.e., by slipping tissue annuloplasty band  100  into the peripheral groove  260 B and attaching elastic ends  110 A,  110 B of axle  70  together. Then tissue annuloplasty band  100  is transferred to the annulus of the patient&#39;s mitral valve in the manner previously described. 
     In another preferred form of the invention, and looking at  FIGS. 14-22 , a tissue annuloplasty band  100 A ( FIG. 20 ) is formed using an external structural mesh  300  (FIG.  16 ). More particularly, graft tissue  310  ( FIG. 14 ) is cut into a preferred long length  320  using a tissue grasper  330  and a tissue cutter  340 , both being standard, commercially-available devices. To aid in inserting tissue length  320  into external mesh  300 , a temporary guide tube  342  ( FIG. 15 ) may be used to hold open the external mesh  300  and guide the tissue length  320  through the mesh. 
     Looking at  FIG. 16 , external mesh  300  is preferably constructed of flexible but not stretchable material such as monofilament or braided suture for permanent implantation into the body. The weave is preferably constructed such that mesh  300  does not stretch in the direction of the long axis via straight members  350 . The weave could also provide a large mesh  360  to allow a significant amount of tissue to be exposed to the implant surface so as to promote implant-to-body tissue in-growth. Purse string sutures  370  at the end of mesh  300  provide a means to secure the tissue graft  320  inside the external mesh and to secure the resulting tissue annuloplasty band  100 A to the mounting ring  140  (or  140 B). If various lengths of bands are required, either individual bands could be provided or a longer band could be cut to the required length. If a longer band is cut to length, extra sets of purse string sutures  370 A provide a means to shorten the band and still secure the tissue  320  within the external mesh. Any unused purse string sutures  370 ,  370 A can be cut prior to fixation of the band to the mounting ring. 
     Looking at  FIG. 16 , guide tube  342  has been inserted through external mesh  300  to provide a smooth path for tissue  320 . A tissue hook  382  and shaft  384  are inserted through guide tube  342 , and then tissue  320  is folded in half and inserted through hook  382  (FIG.  17 ). For this embodiment, tissue  320  must be at least twice as long as the pre-sized band length. An alternative to hook  382  is a grasper (not shown) that pulls a single length of tissue through guide tube  342 . For such an alternative embodiment, a single length of tissue might be wider than a folded length of tissue, such that the volume of tissue inside the external mesh  300  is similar in both embodiments. 
     Looking next at  FIGS. 18-20 , the tissue  320  is pulled through guide tube  400  by pulling on tissue retraction handle  386 . Guide tube  342  is then pulled out from between tissue  320  and external mesh  300 . Any excess tissue  320  is cut to the length of external mesh  300  and purse string sutures  370  are tied closed at  387  to secure the tissue  320  within external mesh  300 , forming a properly sized tissue annuloplasty band  100 A. 
     Looking at  FIGS. 21 and 22 , tissue annuloplasty band  100 A is temporarily secured to a mounting ring (e.g., a pre-sized fixed-diameter mounting ring  140 B) by tying a knot  388  ( FIG. 22 ) using the remaining lengths of purse string sutures  370 . Once the surgeon has sutured the tissue annuloplasty band  100 A to the mitral valve using standard surgical techniques, mounting ring  140 B is removed by cutting and retrieving purse string sutures  370  close to the ends of tissue annuloplasty band  100 A. 
     It is to be understood that the present invention is by no means limited to the particular constructions and method steps disclosed above and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.