Abstract:
A cardiovascular valve assembly comprising a base member that is affixed to a patient using conventional sutures or staples, and a replaceable valve member including a valve frame that supports a plurality of valve leaflets. The valve member mates with the base member, and can be detached from the base member for convenient replacement.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/636,608, filed Dec. 16, 2004, which is hereby fully incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a cardiovascular valve assembly, and more specifically relates to a cardiovascular valve assembly comprised of a base member that remains in a patient, and a valve member that is detachably mountable to the base member. 
     BACKGROUND OF THE INVENTION 
     The current practice of inserting a bioprosthetic cardiovascular valve involves cutting a patient&#39;s chest open, placing the patient on cardiopulmonary bypass, and surgically inserting the valve into an aorta. This process can take several hours and subjects the patient to significant operative mortality. While operative mortality during a first valve replacement surgery can be very low, subsequent valve replacement surgeries have increased operative mortality. Consequently, first and second re-operations to replace a worn out cardiovascular valve are usually avoided. However, since many typical cardiovascular valves have a lifespan of about 10 years, it often becomes necessary to replace cardiovascular valves one or more times. 
     One goal of bioprosthetic cardiovascular valve research has been to improve the durability of cardiovascular valves, so that the valves can be put into patients only once, and will last the life of the patient. Thus far, this goal has been extremely difficult to reach. 
     The present invention addresses deficiencies in the durability of cardiovascular valves by providing a cardiovascular valve that can be easily inserted for initial installation, easily removed when the valve begins to fail, and easily re-inserted for valve replacement. Advances in the field of catheter-based end vascular procedures, and more broadly, the field of Minimally Invasive Surgery (MIS), facilitate procedures for insertion and removal of cardiovascular valves according to the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a cardiovascular valve assembly comprising: (a) a base member; and (b) a valve member detachably mountable to the base member, said valve member including: at least one mounting assembly engageable with the base member, and a wireform for supporting leaflets, said wireform connected with each of said at least one mounting assemblies. 
     An advantage of the present invention is the provision of a cardiovascular valve assembly including a replaceable valve member and a base member, wherein the replaceable valve member is conveniently attachable to and detachable from the base member that can be permanently installed in a patient. 
     Still another advantage of the present invention is the provision of a cardiovascular valve assembly that comprises a replaceable valve member including a valve frame that is sufficiently elastic to allow expansion and collapse thereof. 
     Yet another advantage of the present invention is the provision of a cardiovascular valve assembly including a replaceable valve member having a mounting assembly that can be gripped by snares. 
     These and other advantages will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein: 
         FIG. 1  is a perspective view of a fully assembled cardiovascular valve assembly according to one embodiment of the present invention, the cardiovascular valve assembly including a replaceable valve member and a base member; 
         FIG. 2  is a cross-sectional view of the cardiovascular valve assembly of  FIG. 1 , taken along lines  2 - 2 ; 
         FIG. 3  is an exploded view of the cardiovascular valve assembly of  FIG. 1 , without valve leaflets and a sewing cuff; 
         FIG. 4  is an enlarged exploded view of a mounting assembly shown in  FIG. 3 ; 
         FIG. 5  shows a valve leaflet and an associated frame wrap member; 
         FIG. 6  shows a sewing cuff and an associated base wrap member; 
         FIG. 7  is an exploded view of a valve frame, according to an alternative embodiment; 
         FIG. 7A  is an enlarged partially sectioned view of a wireform according to an alternative embodiment; 
         FIG. 8  is a perspective view of a mounting assembly and a corresponding mounting section, according to an alternative embodiment; 
         FIG. 9  is a front view of the mounting assembly and the corresponding mounting section of  FIG. 8 , wherein said mounting assembly and the corresponding mounting section are in engagement; 
         FIG. 10  is a partial cross-sectional view of the mounting assembly engaged with the corresponding mounting section, taken along lines  10 - 10  of  FIG. 9 ; 
         FIG. 11  is a perspective view of a mounting assembly and a corresponding mounting section, according to another alternative embodiment; 
         FIG. 12  is a side view of the mounting assembly and the corresponding mounting section of  FIG. 11 , wherein said mounting assembly and the corresponding mounting section are in engagement; 
         FIG. 13  is a partial cross-sectional view of the mounting assembly and the corresponding mounting section, taken along lines  13 - 13  of  FIG. 12 . 
         FIG. 14  is a perspective view of a hinged wireform section according to an alternative embodiment; 
         FIG. 15A  is an enlarged cross-sectional view of the hinged wireform section, taken along lines  15 A- 15 A of  FIG. 14 , wherein the wireform section is shown in an uncollapsed state; 
         FIG. 15B  is an enlarged cross-sectional view of the hinged wireform section of  FIG. 15A , wherein the wireform section is shown in a collapsed state; 
         FIG. 16  is a perspective view of a hinged wireform section according to another alternative embodiment; 
         FIG. 17A  is an enlarged cross-sectional view of the wireform section taken along lines  17 A- 17 A of  FIG. 8 , wherein the wireform section is shown in an uncollapsed state; 
         FIG. 17B  is an enlarged cross-sectional view of the wireform section of  FIG. 17A , wherein the wireform is shown in a collapsed state; and 
         FIGS. 18A-18C  illustrate removal of a valve member from a base member using an installation/removal tool. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides improvement to the devices disclosed in U.S. Pat. No. 6,530,952 entitled “Bioprosthetic Cardiovascular Valve System” (issued Mar. 11, 2003) and U.S. Pat. No. 6,569,196 entitled “System for Minimally Invasive Insertion of a Bioprosthetic Heart Valve” (issued May 27, 2003), both of which are fully incorporated herein by reference. Disclosed herein are various embodiments of the present invention. It should be understood that the present invention may be practiced using a combination of features from the various embodiments disclosed herein. In the drawings, similar components of the various embodiments will bear the same reference numbers. 
     Referring now to the drawings wherein the showings are for the purposes of illustrating embodiments of the present invention only and not for the purposes of limiting same,  FIG. 1  illustrates a cardiovascular valve assembly  10  according to one embodiment of the present invention. Cardiovascular valve assembly  10  is basically comprised of a replaceable valve member  20  and a base member  170 . Valve member  20  is generally comprised of a valve frame  30  and a plurality of pericardial leaflets  230  mounted thereto. Base member  170  is sewn to a patient using a sewing cuff  270 , as will be described in detail below. Replaceable valve member  20  is detachably mountable to base member  170 , as will also be described in detail below. 
     A first embodiment of valve member  20  will now be described in detail with reference to  FIGS. 3 and 4 . As discussed above, valve member  20  is generally comprised of valve frame  30  and a plurality of pericardial leaflets  230  mounted thereto. Pericardial leaflets  230  are omitted from  FIGS. 3 and 4  for improved clarity. Valve frame  30  includes a wireform comprised of a plurality of wireform sections  40 , and a mounting assembly  80 . 
     Each wireform section  40  of valve frame  30  has a generally arcuate shape, and has an end portion  42  at distal ends thereof. In the embodiment shown, each end portion  42  is arranged to form a generally circular loop. Wireform sections  40  are preferably made of a medical grade metal wire with suitable elasticity, such as Algiloy, nitinol, stainless steel, platinum, gold, titanium, other biocompatible metals, and combinations thereof. It should be understood that a preferred material for wireform sections  40  has an elasticity such that the material returns to its original shape after being deformed. However, it is contemplated that a material that does not return to its original shape after deformation could also be suitably used. 
     Mounting assembly  80  is comprised of a cap  82  and a support member  100 . In the embodiment shown, cap  82  has a bulbous portion  84 , a neck  86  and a base  88 . A hole  90  extends through cap  82 , as best seen in  FIG. 4 . Cap  82  is an engagement means for facilitating engagement of mounting assembly  80  with an installation/removal tool, as will be described below. 
     Support member  100  comprises a retaining pin  110  and a mounting element  102 . Retaining pin  110  includes a split end  112  having locking tabs  114  extending therefrom. Split end  112  compresses to allow retaining pin  110  to be inserted into hole  90  of cap  82 . Locking tabs  114  extend out through hole  90  and lock cap  82  onto support member  100 , as shown in  FIG. 1 . 
     Mounting element  102  has an inner face  104 , an outer face  106  and a top face  108 . In the illustrated embodiment, mounting element  102  takes the form of a prismatic-shaped “spike” with engagement surfaces formed in inner face  104 . 
     Wireform sections  40  are mounted to support member  100  by first mounting end portions  42  of adjacent wireform sections  40  onto retaining pin  110 . Thereafter, cap  82  is slid onto retaining pin  110  to capture end portions  42  between base  88  of cap  82  and top face  108  of mounting element  102 . As indicated above, locking tabs  114  extend out through hole  90 , thereby locking cap  82  onto support member  100 . 
     It should be appreciated that in accordance with an alternative embodiment of the present invention, the wireform may be comprised of a single continuous wireform section that is connected with each support member  100 . In this regard, loops may be formed in the single continuous wireform section at appropriate locations for mounting to retaining pins  110 . Alternatively, the single continuous wireform section may be connected with the support element by spot welding or other means. 
     While an illustrated embodiment of the present invention shows three (3) wireform sections  40  and three (3) mounting assemblies  80 , it is contemplated that the number of wireform sections  40  and mounting assemblies  80  may be less than or greater than three. 
     Base member  170  will now be described in detail with reference to  FIGS. 3 and 4 . Base member  170  is generally comprised of a plurality of arcuate sections  172 . Holes  176  are located along the length of each arcuate section  172  for attachment of a base wrap  250 , as will be described below. Distal ends  174  of adjacent arcuate sections  172  join a common mounting section  180 . Mounting section  180  includes a mating recess  182  dimensioned to receive mounting element  102  of support member  100 . Mounting element  102  and mounting section  180  define interlocking surface means. Mounting section  180  has an outer face  186  and an upper face  188 . Holes  187  extend through mounting section  180  along the lower end of outer face  186  for attachment of sewing cuff  270  ( FIG. 1 ), as will be described below. 
     As best seen in  FIG. 1 , when mounting element  102  is received into mating recess  182 , outer surface  106  is generally flush with outer face  186  of mounting section  180  and top face  108  is generally flush with upper face  188 . 
     While an illustrated embodiment shows three (3) arcuate sections  172  and three (3) mounting sections  180 , it is contemplated that the number of arcuate sections  172  and mounting sections  180  may be less than or greater than three. 
     Attachment of pericardial leaflets  230  to wireform sections  40  will now be described with reference to  FIGS. 1 ,  2  and  5 . With particular reference to  FIG. 5 , there is shown a pericardial leaflet  230  and a frame wrap  210 . Leaflet  230  has a first end  232  and a second end  234 . First end  232  is fixed relative to valve frame  30 , as will be described below. Second end  234  of leaflet  230  is free to move during ordinary operation of valve member  20 . Leaflet  230  also has an inner surface  236  and an outer surface  238 . In the illustrated embodiment, a frame wrap  210  is used to attach each leaflet  230  to wireform sections  40 , as will be described below. Frame wrap  210  has a first edge  212 , a second edge  214 , an inner surface  216 , and an outer surface  218 . Leaflet  230  and frame wrap  210  are preferably made of a biocompatible, non-thrombogenic material, such as glutaraldehyde-fixed pericardium of bovine, porcine, equine or any other human or animal origin. 
     Referring now to  FIG. 2 , pericardial leaflets  230  are attached to wireform sections  40  by attachment to frame wrap  210 . In this regard, frame wrap  210  is first wrapped around each wireform section  40 , wherein first edge  212  is joined to second edge  214 . First edge  212  is stitched to second edge  214  generally along line  215  to capture wireform section  40 , thereby permanently attaching frame wrap  210  to valve frame  30 . Outer surface  238  of leaflet  230  is then located adjacent to outer surface  218  of frame wrap  210 . First end  232  is stitched to frame wrap  210  generally along line  235 , thereby permanently attaching leaflet  230  to frame wrap  210 . In a preferred embodiment, end  232  of leaflet  230  extends beyond edges  212 ,  214  of frame wrap  210  (e.g., by 1-5 mm) to impede displacement of frame wrap  210  along the length of wireform section  40 . Furthermore, extension of ends  232  beyond edges  212 ,  214  of frame wrap  210  allows leaflets  230  to cover any gap that may exist between valve frame  30  and base member  170  when valve member  20  is fully installed in base member  170 . As a result, blood leakage between valve member  20  and base member  170  is prevented. 
     Attachment of sewing cuff  270  to base member  170  will now be described with reference to  FIGS. 1 ,  2  and  6 . Sewing cuff  270  is provided to attach base member  170  to body tissue inside a patient. With particular reference to  FIG. 6 , there is shown sewing cuff  270  and a base wrap  250 . Sewing cuff  270  preferably takes the form of a ring having an outer edge  272  and an inner edge  274 . Sewing cuff  270  also has an upper surface  276 . Base wrap  250  is attached to each arcuate section  172  of base member  170  to attach sewing cuff  270  to base member  170 , as will be described below. Base wrap  250  has a first edge  252 , a second edge  254 , an inner surface  256 , and an outer surface  258 . Sewing cuff  270  and base wrap  250  are preferably made of Dacron or other medical grade cloth. 
     With further reference to  FIG. 2 , sewing cuff  270  is attached to base member  170  using base wrap  250 . In this regard, each base wrap  250  is wrapped around an arcuate section  172  of base member  170 . First edge  252  is stitched to second edge  254  generally along line  255  to capture each arcuate section  172 , thereby permanently attaching base wrap  250  to base member  170 . Holes  176  located along the length of arcuate sections  172  may be used to directly stitch base wrap  250  to base member  170 . Upper surface  276  of sewing cuff  270  is located adjacent to outer surface  258  of base wrap  250 , as shown in  FIG. 2 . Sewing cuff  270  is stitched to base wrap  250  generally along line  275 , thereby permanently attaching sewing cuff  270  to base member  170 . In the illustrated embodiment, outer edge  272  of sewing cuff  270  extends outward from arcuate sections  172  of base member  170 . Holes  187  of mounting sections  180  may be used to stitch sewing cuff  270  directly to base member  170 . 
     Referring now to  FIG. 7 , there is shown an alternative valve frame  30 A. In this embodiment, a mounting assembly  80 A is comprised of a plate  50 A, a cap  82 A, and a support member  100 A. Plate  50 A is generally planar, and includes recesses  52 A and a hole  54 A. Recesses  52 A are dimensioned to receive end portions  42  of wireform sections  40 . In the illustrated embodiment, end portions  42  are inserted into recesses  52 A and spot welded to plate  50 A. Accordingly, adjacent end portions  42  of wireform sections  40  are joined to a common plate  50 A. Hole  54 A is dimensioned to receive a threaded retaining pin  110 A, described below. Cap  82 A has a bulbous portion  84 A, a neck  86 A and a base  88 A. A threaded recess  90 A extends into cap  82 A from base  88 A. Support member  100 A is comprised of threaded retaining pin  110 A and a mounting element  102 . Threaded retaining pin  110 A is dimensioned to threadingly engage with threaded hole  90 A. Mounting element  102  has been described in detail above. 
     With regard to assembly of mounting assembly  80 A, retaining pin  110 A is inserted through hole  54 A of plate  50 A, and cap  82 A is then threaded onto retaining pin  110 A. Accordingly, plate  50 A is captured between base  88 A of cap  82 A and top face  108  of mounting element  102 . 
     Referring now to  FIG. 7A , there is shown an alternative embodiment of wireform sections  40 . In this embodiment, a kink or bend  44  is located in wireform sections  40  proximate to end portion  42 . Kink or bend  44  helps to prevent slippage or dislocation of frame wrap member  210  along wireform section  40 . 
       FIGS. 8-10  illustrate a valve frame mounting assembly  120  and a base member mounting section  180 A, according to an alternative embodiment of the present invention. In this regard, mounting assembly  120  is generally comprised of a cap  122  and a mounting element  142 . In the embodiment shown, cap  122  has a bulbous portion  124 , a neck  126  and a base  128 . Recesses  132  are located in base  128 , and are dimensioned to receive end portions  42  of adjacent wireform sections  40 . A slot  130  is formed in base  128 , and is dimensioned to receive a portion of mounting section  180 A, as best seen in  FIG. 9 . Mounting element  142  takes the form of a pin or bar that extends across slot  130 , as best seen in  FIGS. 8 and 9 . 
     Mounting section  180 A includes a recess  182 A formed in an upper face  188 A. In the embodiment shown, recess  182 A takes the form of a generally L-shaped slot. Recess  182 A is dimensioned to receive mounting element  142  to attach mounting assembly  120  to mounting section  180 A. Mounting element  142  and mounting section  180 A define interlocking surface means. It should be appreciated that mounting section  180 A has a relatively narrow outer face  186 A. 
       FIGS. 11-13  illustrated a valve frame mounting assembly  80 B and a base member mounting section  180 B according to still another alternative embodiment of the present invention. In this regard, mounting assembly  80 B is comprised of a cap  82 B, a plate  50 B, and a mounting element  56 B. Cap  82 B includes a bulbous portion  84 B, a neck  86 B and a base  88 B. By way of example, and not limitation, cap  82 B may be attached to plate  50 B by spot welding or by a fastener (e.g., a screw). Plate  50 B includes recesses  52 B that are dimensioned to receive end portions  42  of wireform sections  40 . In the embodiment shown, mounting element  56 B takes the form of a clip, hook, or latch member that extends from plate  50 B. In this regard, mounting element  56 B includes a downward extending wall  57 B and an inward extending wall or tab  58 B, as best seen in  FIGS. 11 and 12 . 
     Mounting section  180 B has an outer face  186 B and an upper face  188 B. A slot or recess  182 B is formed in outer face  186 B. Recess  182 B is dimensioned to receive inward extending tab  58 B of plate  50 B to attach mounting assembly  80 B to mounting section  180 B. Mounting element  56 B and mounting section  180 B define interlocking surface means. When tab  58 B is received by recess  182 B, the lower surface of plate  50 B rests on upper face  188 B. It should be appreciated that mounting section  180 B has a relatively narrow outer face  186 B. 
     Referring now to FIGS.  14  and  15 A- 15 B, there is shown an alternative embodiment for the wireform sections. Wireform section  60  is a generally flat ribbon or strip having distal end portions in the form of outward projecting mounting tabs  62 . Each mounting tab  62  includes a hole  66 . Hole  66  is dimensioned to receive a retaining pin for attachment with a mounting assembly, as described above. Holes  65  may be located along the length of wireform section  60  for attachment of base wraps  250  thereto by stitching. At or near the center of wireform  60 , a notch  68  may be formed therein ( FIG. 15A ) to form a “living hinge.” Notch  68  defines a hinged area of wireform  60  that allows wireform section  60  to flex, as shown in  FIG. 15B . Wireform section  60  is preferably made of a medical grade polymer material, such as poly-ether-ether-ketone (PEEK), polyurethane or polycarbonate. The polymer material is preferably fabricated so as to align the molecules along a hinging axis located at notch  68 . 
     Referring now to FIGS.  16  and  17 A- 17 B, there is shown another alternative embodiment of a wireform section. Like wireform section  60 , wireform section  70  also takes the form of a flat ribbon or strip having distal end portions in the form of outward projecting mounting tabs  62 . However, wireform section  70  is comprised of individual wireform portions  70   a  and  70   b  joined together at or near the center of wireform  70  by a connecting pad  75  ( FIG. 17A ). Connecting pad  75  is made of a flexible material that allows wireform portions  70   a  and  70   b  to flex relative to each other, as shown in  FIG. 17B . Thus, connecting pad  75  forms a hinge for wireform portions  70   a  and  70   b . Wireform portions  70   a  and  70   b  are preferably made of a polymer material, such as poly-ether-ether-ketone (PEEK), polyurethane or polycarbonate. Connecting pad  75  is preferably made of a polymer material, such as such as poly-ether-ether-ketone (PEEK), polyurethane or polycarbonate. 
     As indicated above, the wireform of the present invention may be comprised of a single continuous wireform section. In accordance with the embodiments of wireform sections  60  and  70  described above, a single continuous wireform may take the form of a flat ribbon or strip in a ring-like arrangement, wherein mounting tabs are formed in the single continuous wireform section at appropriate locations. 
     Assembly and operation of cardiovascular valve assembly  10  will now be described with reference to a cardiovascular valve assembly  10  according to the embodiment shown in  FIGS. 1-6 . It should be appreciated that operation of the cardiovascular valve assembly according to alternative embodiments described herein is substantially the same. 
     Beginning with initial assembly and installation of cardiovascular valve assembly  10 , a plurality of frame wraps  210  and leaflets  230  are attached to valve frame  30 , as described above, to form a fully assembled valve member  20 . Furthermore, a plurality of base wraps  250  and sewing cuff  270  are attached to base member  170 , as described above. Thereafter, assembly of cardiovascular valve assembly  10  is completed by engaging valve frame  30  with base member  170  ( FIG. 1 ). In this regard, each mounting element  102  of mounting assemblies  80  is received into a respective mating recess  182  of mounting sections  180 . When assembled, wireform sections  40  of valve frame  30  will extend generally parallel to arcuate sections  172  of base member  170 . It should be understood that engagement of valve frame  30  with base member  170  may require a small temporary expansion of valve frame  30  in order to fit mounting elements  102  into respective mating recesses  182 . Thereafter, fully assembled cardiovascular valve assembly  10  is sewn to a patient using sewing cuff  270 . 
     When it becomes necessary to replace valve member  20 , an installation/removal tool  300  may be used (see  FIGS. 18A-18C ). Tool  300  includes a plurality of preformed, retractable snares  310  and a plurality of expander elements  320 . In the illustrated embodiment, there are three snares  310  and three expander elements  320 . However, it is contemplated that the number of snares and expander elements may vary depending upon the configuration of cardiovascular valve assembly  10 . Each expanding element  320  has an engagement member  322  at a distal end thereof. Tool  300  allows for removal and insertion of valve member  20  in a simple pull-out/push-in operation that does not require visualization once tool  300  is attached to the valve member  20 , as will be described below 
     Removal of valve member  20  from base member  170  will now be described in detail with reference to  FIGS. 18A-18C . To separate valve member  20  from base member  170 , snares  310  are looped around necks  86  of each cap  82  ( FIG. 18A ). It should be appreciated that the shape and location of cap  82  allows cap  82  to be grabbed by snares  310  even if there is considerable tissue overgrowth. 
     Referring now to  FIG. 18B , mounting elements  102  are disengaged from mounting sections  180  by engaging engagement member  322  of each expanding element  320  with neck  86  of each cap  82 . Expanding elements  320  are moved from a retracted position to an expanded position to simultaneously force each mounting assembly  80  outward, thereby disengaging mounting elements  102  from mounting sections  180 . As a result, valve member  20  is released from base member  170 . Thereafter, valve member  20  may then be partially or fully collapsed by moving engagement members  322  from the expanded position to the retracted position, and drawing snares  310  inward, as shown in  FIG. 18C . Accordingly, valve member  20  can be conveniently withdrawn from the aorta through a port access system (not shown). The port access system may take the form of a temporary Dacron graft sewn onto the vessel. 
     A replacement valve member  20  is installed by generally reversing the operation described above for removal. 
     It should be understood that valve member  20  is detachable from base member  170  by way of outward deflection of valve frame  30  at mounting assembly  80 . Deflection may occur by use of installation/removal tool  300 , as described above, or alternatively by a surgeon&#39;s fingers. 
     According to a preferred embodiment of the present invention wireform sections  40  of the valve frame  30  are made of a deformable material and/or include hinge means, as described above. However, it is also contemplated that according to an alternative embodiment of the present invention wireform sections  40  may be generally rigid (i.e., not be made of a deformable material and/or include any hinge means), and thus do not collapsible as described above. 
     Other modifications and alterations will occur to others upon their reading and understanding of the specification. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.