Abstract:
An apparatus and method are disclosed for supporting a heart valve with a flexible girdle. The girdle has an elongated cylindrical sidewall having an axial length at least commensurate with the heart valve. The girdle is disposed around a tubular valve wall of the heart valve being implanted so that the inflow end of the girdle is adjacent the inflow end of the tubular valve wall. The inflow ends of the girdle and heart valve may then be sutured together to implant the valve. The girdle provides support to stabilize the heart valve and inhibit deformation thereof.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to U.S. patent application Ser. No. 09/1052,707, now U.S. Pat. No. 5,935,163, which was filed Mar. 31, 1998 and entitled Natural Tissue Heart Valve Prosthesis. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an apparatus and method for supporting a heart valve. More particularly, the present invention relates to an apparatus and method for supporting a heart valve by disposing a girdle externally about the valve. 
     BACKGROUND OF THE INVENTION 
     The use of a patient&#39;s healthy pulmonic valve as an autograft to replace a diseased aortic valve has been gaining worldwide acceptance as a viable alternative for replacing the patient&#39;s diseased aortic valve. This procedure is known as the Ross procedure after the surgeon who introduced the procedure in 1967. 
     The Ross procedure is performed by transplanting a patient&#39;s healthy pulmonic valve along with a portion of the pulmonary artery to replace the aortic valve and a few centimeters of the aorta. The left and right coronary arteries are attached to the valve wall of the pulmonary autograft after making small slits through the valve wall into coronary sinuses of the autograft. 
     The pulmonic valve is typically replaced by a homograft, such as a pulmonic or aortic heart valve from a cadaver. The Ross procedure is preferred over other heart valve replacement procedures, especially for individuals who are unable to take anticoagulation drugs. The Ross procedure has received substantial discussion in various publications. 
     For example, Oury et al., An Appraisal of the Ross Procedure: Goals and Technical Guidelines, Operative Techniques in Cardiac and Thoracic Surgery, Vol. 2, No. 4 (November), 1997: pp. 289-301, describes the Ross procedure as well as some alternative techniques for performing the procedure. 
     Black et al., Modified Pulnronary Autograft Aortic Root Replacement: The Sinus Obliteration Technique, Ann Thoracic Surgery, 1995; 60:1434-1436, describes a rather complicated technique to remedy a frequent problem of dilation of the pulmonary autograft following the Ross procedure. This approach utilizes large coronary buttons to replace the pulmonary sinus completely and leaves the non-coronary aortic sinus to support the non-coronary sinus of the pulmonary autograft. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an external support apparatus for a heart valve that is disposed within an elongated tubular valve wall. The apparatus includes a girdle having an elongated cylindrical sidewall with inflow and outflow ends that are spaced apart an axial length that is at least substantially commensurate with the axial length of the heart valve disposed within the tubular valve wall. 
     Preferably, at least two apertures are formed through the sidewall of the girdle and spaced axially from the inflow end thereof. The apertures are spaced circumferentially apart for generally radial alignment with corresponding sinuses of the heart valve which is to be supported by the girdle. The inflow end of the girdle preferably is folded toward the outflow end to provide additional support at its inflow end. 
     In another embodiment, the girdle, as described above, is further supported by a stent disposed externally about the sidewall of the girdle. 
     Yet another embodiment of the present invention is directed to a method for improving implantation of a heart valve having inflow and outflow ends and located within a tubular valve wall. An elongated cylindrical girdle is disposed about the tubular valve wall and the heart valve located therein so as to inhibit deformation of the heart valve. The girdle has a cylindrical sidewall portion with inflow and outflow ends spaced apart an axial length at least substantially commensurate with the axial length of the heart valve located within the zubular valve wall. The inflow end of the girdle is positioned adjacent the inflow end of the tubular valve wall. During implantation of the heart valve, the inflow ends of the valve and girdle preferably are secured together to an outflow annulus of the heart. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, wherein: 
     FIG. 1 is a first embodiment of an apparatus in accordance with the present invention; 
     FIG. 2 is a second embodiment of an apparatus in accordance with the present invention; 
     FIG. 3 is a third embodiment of an apparatus in accordance with the present invention; 
     FIG. 4 is a fourth embodiment of an apparatus in accordance with the present invention; 
     FIG. 5 is a fifth embodiment of an apparatus in accordance with the present invention; 
     FIG. 6 is a sixth embodiment of an apparatus in accordance with the present invention; 
     FIG. 7 is an is ometric view of the apparatus of FIG. 1 mounted to a heart valve being implanted to a patient&#39;s heart; 
     FIG. 8 is an isometric view, similar to FIG. 7, illustrating a completed heart valve transplant procedure using the apparatus of FIG. 1; and 
     FIG. 9 is an isometric view of the apparatus of FIG. 5 disposed about a heart valve in accordance with the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a first embodiment of a heart valve girdle  10  in accordance with the present invention. The girdle  10  has an inflow end  14  and an outflow end  16  spaced apart by a length of a cylindrical sidewall  18 . The terms “inflow” and “outflow” are used herein to refer to ends of the girdle which are to be positioned at corresponding ends of a heart valve. 
     Because the girdle  10  is to be mounted externally about a heart valve, such as an autogenous or homogenous heart valve disposed within a length of a tubular valve wall, the axial length of the sidewall  18  is at least substantially commensurate with the axial length of the heart valve which is to be mounted therein. The girdle  10  also has an inner diameter substantially equal to the outer diameter of the tubular valve wall surrounding the heart valve. The girdle  10  my by provided in a variety of sizes from which a surgeon may select an appropriate size of girdle. The elongated sidewall  18  supports and stabilizes the heart valve from its inflow end to its outflow end, thereby inhibiting deformation of the valve when implanted. 
     Preferably, the girdle  10  is formed from a sheet of a flexible material. The flexible material may, for example, be a textile material, such as Dacron, or an animal tissue material, such as bovine pericardium, equine pericardium, porcine pericardium, human pericardium, or other biological materials. The girdle  10  alternatively could be formed of a flexible plastic-like material, such as a natural or synthetic polymer, for example, Delrin. 
     In the preferred embodiment, the girdle  10  is formed from a strip of pericardium which has been treated, or tanned, to render the tissue biocompatible, as is known in the art. The cyLindrical sidewall  18  of the girdle  10  is, for example, formed from a rectangular strip of pericardium having ends that have been attached together end-to-end, such as by sutures  20 . The pericardial tissue may be treated before and/or after the girdle  10  has been formed into its tubular configuration. By treating the pericardial tissue material mounted over a right circular, cylindrical mandrel, for example, the girdle  10  is permanently fixed in its desired tubular shape. 
     At least two and preferably three apertures  22 ,  24  and  26  are formed through the sidewall  18  of the girdle  10  at an axial location intermediate the first and second ends  14  and  16 . In order to facilitate proper alignment of the girdle  10  about the heart valve, each of the apertures  22 ,  24  and  26  is spaced circumferentially apart for generally radial alignment with a corresponding sinus of the heart valve to be mounted therein. By way of example, a pulmonic autograft, as well as a homograft, such as from a cadaver, has three leaflets with sinuses located at the outflow end of the valve between commissures of each adjacent pair of leaflets. The apertures  22 ,  24 , and  26  of the girdle  10  are spaced circumferentially apart from adjacent apertures, generally about 120° apart, so as to correspond to a location of a respective sinus of the heart valve. 
     The inflow end  14  of the girdle  10  preferably is folded radially outward and toward the outflow end  16  of the girdle to form an outer folded portion  27 . The radially outer folded portion  27  is connected to the radially inner portion of the sidewall  18 , such as by sutures  28 . This provides two overlapping layers of the sidewall  18  at the inflow end  14  of the girdle  10  to further help stabilize the inflow end of the heart valve. The folded portion  27  also provides an implantation flange to facilitate implantation of the heart valve to an outflow annulus of the heart as well as to inhibit dilation of the heart valve. 
     FIG. 2 illustrates a second embodiment of a girdle  10 ′ in accordance with the present invention in which reference numbers, modified by adding a prime symbol, are used to refer to similar parts of the girdle of FIG.  1 . The apertures  22 ′,  24 ′, and  26 ′ are substantially enlarged when compared to the apertures of FIG.  1 . Specifically, the circumferential arc of the sidewall  18  extending between adjacent apertures  22 ′,  24 ′ and  26 ′ is substantially less than the circumferential arc of each aperture. In addition, the axial length of sidewall portion  18 ′ between each aperture  22 ′,  24 ′ and  26 ′ and the inflow and outflow ends  14 ′ and  16 ′ also is substantially less than the axial length of each aperture. 
     The girdle  10 ′ of FIG. 2 advantageously facilitates the positioning of the girdle around the heart valve. This is because two of the large apertures  22 ′,  24 ′,  26 ′ are more easily aligned with coronary sinuses of the heart valve being implanted. Attachment of the coronary arteries to the valve wall of a heart valve mounted within the girdle  101  also is facilitated because of the larger surface area of the valve&#39;s sidewall exposed through each aperture  22 ′,  24 ′ and  26 ′. 
     FIG. 3 is a third embodiment of a girdle  100  in accordance with the present invention. The girdle  100  includes an elongated inner tubular sheath  102  having an elongated cylindrical sidewall  104  which, like the embodiments of FIGS. 1 and 2, has an axial length at least substantially commensurate with the axial length of the heart valve to be mounted therein. The inner sheath  102  has an inflow end  106  and an outflow end  108  spaced apart by the sidewall portion  104 . 
     A stent  110  having an annular inflow end  112  and an outflow end  114  is disposed about the inner sheath  102  intermediate its inflow and outflow ends  106  and  108 , respectively. The stent  110  preferably fits snugly over the inner sheath  102 . The stent  110  is formed of a flexible material, suitably a resilient metal or a plastic-like material, such as Delrin. Other resilient, flexible materials such as textile materials, pericardial tissue, or other biocompatible materials, also may be used to form the stent  110 . 
     At least the outflow end  114  of the stent  110  is generally sinusoidal with alternating peaks  116 ,  118 ,  120  and sinuses  122 ,  124 ,  126 , respectively. The peaks  116 ,  118 , and  120  are defined by elongated stent posts  128 ,  130 , and  132 , which are spaced circumferentially apart. The sinuses  122 ,  124 , and  126  are formed between each adjacent pair of stent posts  128 ,  130  and  132 . The circumferential positioning of the stent posts  128 ,  130 , and  132  corresponds to the circumferential positioning of the commissures of adjacent leaflets of the heart valve. 
     An outer sheath  134  of a biocompatible material, such as pericardium, a textile material, or any other biocompatible, flexible material, covers the stent  110  and at least a substantial portion of the inner sheath  102 . The outer sheath  134  has an inflow end  136  and an outflow end  138  spaced axially apart from the inflow end  136  by a length of cylindrical sidewall  140 . 
     The inflow end  136  of the outer sheath  134  is positioned adjacent the inflow end  106  of the inner sheath  102 . The overlapping Layers adjacent the inflow ends  132  and  106  provide additional support at the inflow end of the heart valve, similar to the folded portions  27  and  27 ′ of FIGS. 1 and 2, respectively. A fold also may be added to one or both of the inflow ends  106 ,  136  to provide further stabilization at the inflow end of the heart valve. 
     The outflow end  138  of the outer sheath  134  is spaced from the outflow end  114  of the stent  110 . Preferably, the outflow end  138  of the outer sheath  134  is contoured according to the outflow end  114  of the stent  110 . That is, it has elongated flanges  142 ,  144  and  146 , which cover each of the respective stent posts  128 ,  130 , and  132 . Sinuses are formed between adjacent pairs of flanges  142 ,  144 ,  146 . The outflow end  138  of the outer sheath  134  is connected to the sidewall  104  of the inner sheath  102 , such as by sutures  148 . The sutures  148  limit or prevent axial movement of the stent  110  in a direction from the inflow end  106  toward the outflow end  108  of the inner sheath  102 . 
     The sidewall portions  104  and  140  alternatively could be coextensive, with the outflow end  138  of the outer sheath  134  connected to the outflow end  108  of the inner sheath  102 . In addition, the inflow ends  106  and  136  and may be connected together by sutures (See FIG. 8) when the heart valve is implanted to an appropriate outflow annulus of a patient&#39;s heart. This maintains the axial as well as angular positioning of the stent  110  between the inflow and outflow ends  136  and  138  of the outer sheath  134 . 
     FIG. 4 is another embodiment of a girdle  100 ′, in accordance with the present invention, in which a prime symbol (′) has been added to the reference numbers of FIG. 3 to indicate corresponding parts. The girdle  100 ′ is substantially identical to the girdle  100  of FIG.  3 . However, a plurality of apertures  150 ,  152  and  154  are formed through the sidewall  104 ′ of the inner sheath  102 ′. 
     The apertures  150 ,  152 , and  154  are substantially identical to the apertures  22 ,  24  and  26  shown and described with respect to FIG.  1 . The apertures  150 ,  152 , and  154  are spaced axially apart from the inflow and outflow ends  106 ′ and  108 ′. The apertures  150 ,  152 , and  154  also are spaced axially from the sinusoidal outflow end  138 ′ of the outer sheath  134 ′. In addition, the apertures  150 ,  152 , and  154  are spaced circumferentially apart and located intermediate adjacent stent posts  128 ′,  130 ′ and  132 ′ for generally radial alignment with corresponding sinuses of a heart valve to be mounted therein. The apertures  150 ,  152 , and  154  provide access to the sinuses of the heart valve, such as a pulmonary autograft, to facilitate connecting the left and right coronary arteries through the apertures and to the valve wall surrounding the heart valve. 
     FIG. 5 is another embodiment of a girdle  100 ″ in accordance with the present invention in which a double prime symbol (″) has been added to reference numbers of FIGS. 3 and 4 to indicate corresponding parts. The girdle  100 ″ is substantially identical to the girdle  100 ′ of FIG. 4, although the apertures  150 ″,  152 ″, and  154 ″ have been enlarged to facilitate alignment of two of the apertures  150 ″,  152 ″, and  154 ″ with coronary sinuses of the heart valve to be mounted therein. Specifically, the outer sheath  134 ″ has a sinusoidal outflow end  138 ″ with elongated flanges  142 ″,  144 ″ and  146 ″ radially aligned with and covering respective stent posts  128 ″,  130 ″ and  132 ″. Sinuses are formed between adjacent flanges  142 ″,  144 ″,  146 ″. The apertures  150 ″,  152 ″, and  154 ″ are formed through the inner sheath  102 ″ coextensively with each such sinus of the outer sheath  134 ″. The circumferential arc of the sidewall portion  104 ″ extending between adjacent apertures  150 ″,  152 ″ and  154 ″, e.g. the circumferential arc length of flanges  142 ″,  144 ″ and  146 ″, is substantially less than the circumferential arc of each aperture. 
     FIG. 6 illustrates yet another embodiment of a girdle  200  in accordance with the present invention. The girdle  200  is generally similar to the girdles  100 ,  100 ′, and  100 ″ of FIGS. 3-5. The girdle  200  includes an elongated inner sheath  202  having an inflow end  204  and an outflow end  206  spaced axially apart by a cylindrical sidewall portion  208 . 
     In this embodiment, the outflow end  206  of the inner sheath  202  is sinusoidal to correspond to the contour of the outflow end of a heart valve to be mounted therein. Specifically, the outflow end  206  includes a plurality of elongated flanges  210 ,  212 , and  214  which are spaced circumferentially apart. In this way, sinuses  216 ,  218 , and  220  are formed in the outflow end  206  between each adjacent pair of flanges  210 ,  212 , and  214 . 
     A flexible stent or annular ring  222 , which is substantially identical to that shown and described with respect to FIGS. 3-5, is disposed about the inner sheath  202  to provide additional radial support. The stent  222  includes axially spaced apart inflow and outflow ends  224  and  226 . The outflow end  226  is sinusoidal with circumferentially spaced apart and elongated stent posts  228 ,  230 , and  232  extending axially from the annular portion at inflow end  224 . Each stent post  228 ,  230 , and  232  is radially aligned and extends substantially coextensively with one of the respective flanges  210 ,  212 , and  214 , as shown in FIG.  6 . The stent  222  also has sinuses  229 ,  231  and  233  formed between adjacent pairs of stent posts  228 ,  230  and  232 . The inflow and outflow ends  224  and  226  of the stent  222  are spaced axially apart from the respective inflow and outflow ends  204  and  206  of the inner sheath  202  to form a generally cylindrical sidewall portion therebetween. 
     An outer sheath  236  of a flexible material, such as a textile or animal tissue material, is disposed externally over the stent  222  and at least a portion of the inner sheath  202 . The outer sheath  236  has an inflow end  238  adjacent the inflow end  204  of the inner sheath  202  and an outflow end  240  adjacent the outflow end  206  of the inner sheath. Preferably, the outflow end  240  of the outer sheath  236  also is sinusoidal with corresponding elongated peaks or flanges  242 ,  244 , and  246  radially aligned and substantially coextensive with the respective flanges  210 ,  212 , and  214  of the inner sheath  202  and the stent posts  228 ,  230 , and  232 . The outflow end  240  also has sinuses at its outflow end intermediate adjacent pairs of the elongated peaks  242 ,  244 , and  246 , which outer sheath sinuses are aligned with the inner sheath sinuses  216 ,  218 , and  220 . The outer sheath  236  alternatively may have an axial length about equal with axial length of the inner sheath  202 , so that the stent  222  is sandwiched between concentric inner and outer cylindrical sheaths. 
     In view of the various embodiments of girdles described above, their use may be better appreciated with reference to FIGS. 7-9. While FIGS. 7-9 disclose the use of two particular girdle embodiments, it will be understood and appreciated that each of the girdle embodiments shown in FIGS. 1-6 may, in accordance with the present invention, be used to support a heart valve being implanted. 
     FIG. 7 illustrates part of a surgical procedure in which a girdle  300 , as shown in FIG. 1, has been attached about an autogenous heart valve, preferably a pulmonary autograft  302 . The procedure preferably follows the steps of the Ross procedure, such as described in Oury et al., An Appraisal of the Ross Procedure: Goals and Technical Guidelines, Operative Techniques in Cardiac and Thoracic Surgery, Vol. 2, No. 4 (November), 1997: pp. 289-301, which is incorporated herein by reference. 
     In FIG. 7, the Ross procedure is at an intermediate stage in which the diseased aortic valve already has been removed and discarded. A pulmonary autograft  302  is formed of a healthy pulmonary heart valve  303  which is disposed within an elongated portion of the tubular valve wall or pulmonary artery  306 . The portion of the pulmonary artery  306  enclosing the heart valve  303  has been excised from the pulmonary trunk of the patient. 
     The external support girdle  300 , in accordance with the present invention, is disposed about the pulmonary autograft valve  302 . The girdle  300  has apertures  308  and  310  which are radially and axially aligned with the sinuses of coronary leaflets  312  and  314  of the pulmonary autograft  302 . 
     During the Ross procedure, small incisions or slits are made in the tubular valve wall  306  of the pulmonary autograft  302  over which buttons  318  and  320  are attached. The buttons  318  and  320  are formed of sidewall portions of the aortic valve wall from the patient&#39;s aortic valve which has been removed. The buttons  318  and  320  are connected with the right and left coronary arteries  322  and  324 , respectively. The right and left coronary arteries  322  and  324  terminate at the buttons  318  and  320  to form ostias or openings  326  and  328  which are subsequently aligned with slits formed in the valve wall  306  of the pulmonary autograft  302 . 
     As shown in FIG. 7, the girdle  300  has an outflow end  330  located adjacent but spaced apart from an outflow end  332  of the pulmonary valve wall  306 . An inflow end  334  of the girdle  300  is located adjacent an inflow end  336  of the pulmonary valve wall  306  and includes a fold  338 , as described above, to help inhibit dilation at the inflow end  336  of the pulmonary autograft  302 . The outflow end  332  of the pulmonary valve wall  306  is anastomosed to the aorta  340 , such as by sutures  342 . 
     Another girdle  348 , in accordance with the present invention, is mounted over a homograft heart valve  350 . The homograft  350  has an outflow end  352  which has been anastomosed to the pulmonary trunk  354 . An inflow end  356  of the girdle  348  is positioned adjacent the inflow end  358  of the homograft  350 . An outflow end  360  of the girdle  348  preferably is spaced from the outflow end  352  of the homograft  350 , although it easily could be made longer so that the girdle  348  and homograft  350  are coextensive. 
     While the girdle  348  is shown to include apertures  362  and  364 , such apertures are superfluous for the pulmonary valve replacement. However, manufacturing costs may be reduced by fabricating a single type of girdle  300 ,  348  for use during the Ross procedure. The girdles  300 ,  348  typically are produced in various sizes which are to be selected by the surgeon performing the procedure. 
     FIG. 8 illustrates the completed procedure in which the inflow end  336  of the pulmonary autograft  302  and the inflow end  334  of the girdle  300  have been connected together and anastomosed to the right ventricle outflow tract  370 , suitably by interrupted or continuous sutures  372 . In addition, the right and left coronary artery buttons  318  and  320  have been connected over appropriate slits (not shown) formed in the pulmonary valve wall  306  through the apertures  308  and  310 , thereby connecting the coronary arteries with coronary sinuses of the autograft  302 . The inflow end  356  of the girdle  348  and the inflow end of the pulmonary homograft  350  also are connected together and are anastomosed to the left ventricle outflow tract  376  by sutures  378 . 
     FIG. 9 illustrates a heart valve, such as a pulmonary valve  401  disposed within its outer tubular valve wall  402  define a pulmonary autograft  403 . The autograft  403  is mounted within a girdle  404 , such as the girdle shown in FIG.  5 . As can be seen, each sinus  406 ,  408 , and  410  formed in the outflow end of the valve  401  is aligned with a corresponding sinus  412 ,  414  and  416  of the girdle  404 . An inflow end  418  of the girdle  404  is positioned ad.,acent the inflow end  419  of the valve wall  402 . The inflow ends  418  and  419  are connected together and anastomosed to an outflow annulus, schematically indicated at  422 , by sutures  424 . An outflow end  426  of the pulmonary valve wall  402  extends axially beyond an outflow end  428  of the tubular inner sheath  430  of the girdle  404 . The outflow end  426  of the valve wall  402  will be anastomosed to the aorta (not shown) in a manner known in the art. 
     Left and right coronary arteries  430  and  432  are attached to the valve wall  402  through respective apertures  434  and  436  of the girdle  404 . In particular, the coronary arteries  430  and  432  terminate in buttons  438  and  440  which are anastomosed to the valve wall  402  over slits or apertures (not shown) that have been formed through the valve wall. Such slits provide access into coronary sinuses  408  and  406  of the valve  401 . 
     Advantageously, a girdle, in accordance with the present invention, stabilizes the base of the heart valve and supports the commissures so as to inhibit their inward deflection. The girdle also increases the durability of the autograft and homograft valve by inhibiting annular dilation and/or deformities which might otherwise occur during normal functioning of the heart. Such deformities often lead to malcoaptation which, in turn, tends to cause insufficiency and failure. The girdles advantageously promote coaptation of the leaflets of the autograft and homograft. This, in turn, reduces the likelihood of failure and the need for reoperation after surgical procedures, such as the Ross procedure. 
     Each of the girdles of FIGS. 1-6 also may be formed entirely of an absorbable synthetic or biological material, such as an absorbable textile material or an absorbable treated animal tissue material, for example, pericardium. The absorbable material girdle is especially advantageous for young patient&#39;s undergoing the Ross procedure. Because the autograft is formed of the patient&#39;s own tissue, for relatively young individuals, the autograft will continue to grow after being implanted. As stated above, the absorbable girdle stabilizes the transplanted pulmonary autograft for an extended period of time. The absorbable girdle, by its very nature, is slowly absorbed. This permits the transplanted autograft, including the heart valve and corresponding tubular valve wall, to grow with the patient. 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.