Patent Publication Number: US-11654020-B2

Title: Hybrid heart valves

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/199,748, filed Jun. 30, 2016, now issued as U.S. Pat. No. 10,456,246, which claims the benefit of U.S. Application No. 62/188,465, filed Jul. 2, 2015, the entire disclosure of which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a hybrid heart valve for heart valve replacement, and more particularly to modifications to simplify the construction of hybrid heart valves. 
     BACKGROUND 
     The heart is a hollow muscular organ having four pumping chambers separated by four heart valves: aortic, mitral (or bicuspid), tricuspid, and pulmonary. Heart valves are comprised of a dense fibrous ring known as the annulus, and leaflets or cusps attached to the annulus. 
     Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. In a traditional valve replacement operation, the damaged leaflets are typically excised and the annulus sculpted to receive a replacement prosthetic valve. 
     In tissue-type valves, a whole xenograft valve (e.g., porcine) or a plurality of xenograft leaflets (e.g., bovine pericardium) can provide fluid occluding surfaces. Synthetic leaflets have been proposed, and thus the term “flexible leaflet valve” refers to both natural and artificial “tissue-type” valves. In a typical tissue-type valve, two or more flexible leaflets are mounted within a peripheral support structure that usually includes posts or commissures extending in the outflow direction to mimic natural fibrous commissures in the native annulus. The metallic or polymeric “support frame,” sometimes called a “wireform” or “stent,” has a plurality (typically three) of large radius cusps supporting the cusp region of the flexible leaflets (e.g., either a whole xenograft valve or three separate leaflets). The ends of each pair of adjacent cusps converge somewhat asymptotically to form upstanding commissures that terminate in tips, each extending in the opposite direction as the arcuate cusps and having a relatively smaller radius. Components of the valve are usually assembled with one or more biocompatible fabrics (e.g., polyester, for example, Dacron® polyethylene terephthalate (PET)) coverings, and a fabric-covered sewing ring is provided on the inflow end of the peripheral support structure. 
     There is a need for a prosthetic valve that can be surgically implanted in a body channel in a more efficient procedure so as to reduce the time required on extracorporeal circulation. One solution especially for aortic valve replacement is provided by the Edwards Intuity® valve system available from Edwards Lifesciences of Irvine, Calif. Aspects of the Edwards Intuity® valve system are disclosed in U.S. Pat. No. 8,641,757 to Pintor, et al. The Edwards Intuity® valve is a hybrid of a surgical valve and a plastically-expandable stent that helps secure the valve in place in a shorter amount of time. 
     Despite certain advances in this area, there remains a need for a simplified prosthetic heart valve that facilitates implant and simplifies manufacturing techniques. 
     SUMMARY 
     The application discloses a hybrid prosthetic heart valve (and methods for making the same) having a stent frame positioned at the inflow end of the prosthetic heart valve configured to plastically expand into a substantially flared shape when subjected to a dilation force that is by itself insufficient to cause expansion of the main support structure. The stent frame is positioned upstream or on the inflow end of the entire valve portion. The application also discloses a hybrid prosthetic heart valve configured to receive a prosthetic heart valve, such as a catheter-deployed (transcatheter) prosthetic heart valve, therein—e.g., it is adapted for valve-in-valve (ViV) procedures. 
     An exemplary hybrid prosthetic heart valve having an inflow end and an outflow end, and comprises a valve member including a plurality of flexible leaflets configured to ensure one-way blood flow therethrough. A generally tubular expandable inflow stent frame having a radially-expandable inflow end and an outflow end is secured to and projects from an inflow end of the valve member. The outflow end of the stent frame undulates with peaks and valleys, and the outflow end includes integrated commissure posts to which the leaflets attach. The outflow end of the stent frame has a circumferential structure defining a nominal diameter that enables physiological functioning of the valve member when implanted. The circumferential structure is radially expandable from the nominal diameter to a larger expanded diameter upon application of an outward dilatory force from within the stent frame substantially larger than forces associated with normal physiological use. And the circumferential structure has limited radially compressibility of between about 7-20% of the nominal diameter to reduce the size of the outflow end during delivery of the heart valve. 
     A further hybrid prosthetic heart valve disclosed herein and adapted for post-implant expansion has an inflow end and an outflow end with a valve member and an inflow stent frame. The valve member includes an undulating wireform supporting a plurality of flexible leaflets configured to ensure one-way blood flow therethrough. The stent frame is plastically-expandable with a radially-expandable inflow end and an outflow end secured to an inflow end of the wireform. The stent frame projects from the inflow end of the wireform and the outflow end undulates with peaks and valleys corresponding to the wireform. The outflow end further includes integrated commissure posts to which the leaflets attach, and defines an implant circumference that is non-compressible in normal physiological use and has a nominal diameter. The stent frame outflow end permits expansion from the nominal diameter to a second diameter larger than the nominal diameter upon application of an outward dilatory force from within the outflow end substantially larger than forces associated with normal physiological use. 
     Another hybrid prosthetic heart valve disclosed herein comprises a valve member including an undulating wireform supporting a plurality of flexible leaflets configured to ensure one-way blood flow therethrough. A plastically-expandable inflow stent frame having a radially-expandable inflow end and an outflow end is secured to an inflow end of the wireform. The stent frame projects from the inflow end of the wireform and the outflow end undulates with peaks and valleys corresponding to the wireform. The outflow end includes integrated commissure posts to which the leaflets attach outside of the wireform, and the outflow end comprises a circumferential structure defining a nominal diameter that enables functioning of the valve member. The circumferential structure is radially compressible to a smaller contracted diameter to enable compression of the outflow end during delivery of the heart valve, and radially expandable from the nominal diameter to a larger expanded diameter upon application of an outward dilatory force from within the stent frame substantially larger than forces associated with normal physiological use. 
     Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is an exploded view of an inner structural band subassembly of a prior art prosthetic heart valve, and  FIG.  1 B  shows the band subassembly having been covered with cloth and exploded over a peripheral sealing ring; 
         FIG.  1 C  shows the cloth-covered band subassembly joined with the peripheral sealing ring also covered in cloth, while  FIG.  1 D  is a vertical sectional view through a cusp region thereof; 
         FIG.  2 A  is a perspective view of a flexible leaflet subassembly for use in the prior art prosthetic heart valve, and  FIG.  2 B  shows an undulating wireform used for support thereof; 
         FIG.  2 C  is a perspective view of a subassembly of the undulating wireform covered in fabric, and  FIG.  2 D  is a detailed sectional view of a cusp portion thereof; 
         FIG.  2 E  shows a leaflet and wireform subassembly for prior art prosthetic heart valves; 
         FIG.  3    is a perspective view of a finished prior art prosthetic heart valve including the combination of the subassemblies shown in  FIGS.  1 C and  2 E ; 
         FIGS.  4 A and  4 B  are inflow and outflow perspective views, respectively, of a prosthetic heart valve as in  FIG.  3    before coupling with an inflow anchoring skirt to form a hybrid prosthetic heart valve; 
         FIG.  5    is an exploded assembly view of a portion of a cloth-covered anchoring skirt for coupling to the heart valve; 
         FIG.  6    is an exploded assembly view of the portion of the cloth-covered anchoring skirt shown in  FIG.  5    and a lower sealing flange secured thereto to form the inflow anchoring skirt; 
         FIG.  7 A  shows the valve member above the cloth-covered anchoring skirt and schematically shows one method of coupling the two elements, while  FIG.  7 B  illustrates an inner plastically-expandable stent frame of the anchoring skirt and the pattern of coupling sutures passed therethrough; 
         FIG.  8 A  is a side view of a hybrid prosthetic heart valve of the present application, while  FIG.  8 B  shows an anchoring skirt therefor with a valve member in phantom, and  FIG.  8 C  is a perspective view of the prosthetic heart valve with portions cutaway to reveal internal structural leaflet supports; 
         FIGS.  9 A- 9 C  are perspective views of an exemplary anchoring skirt for use in the hybrid prosthetic heart valve of  FIGS.  8 A- 8 C ; 
         FIG.  10 A  is an exploded perspective view of components of an alternative hybrid prosthetic heart valve, while  FIG.  10 B  shows an exemplary leaflet and wireform subassembly and an anchoring skirt and commissure post subassembly for the hybrid prosthetic heart valve; 
         FIGS.  10 C and  10 D  show details of separate commissure posts; 
         FIG.  11    is another exploded perspective view of subassemblies of the alternative hybrid prosthetic heart valve; 
         FIG.  12    shows the relative positions of the anchoring skirt and commissure post subassembly and wireform for the alternative hybrid prosthetic heart valve, and  FIGS.  12 A- 12 D  are further detailed views thereof; 
         FIG.  13    is a perspective view of the finished hybrid prosthetic heart valve; 
         FIGS.  14 A and  14 B  are perspective views of a hybrid prosthetic heart valve built using the methods of  FIGS.  15 - 16   ; 
         FIGS.  15 A and  15 B  show steps for covering an anchoring frame member with cloth in the disclosed method of hybrid valve construction; 
         FIGS.  16 A and  16 B  show methods of attachment of a suture permeable sealing ring to the anchoring frame member; 
         FIG.  17    is a perspective view of a separate commissure post, and  FIG.  18    is the commissure post covered with cloth; 
         FIGS.  19 A and  19 B  are elevational views of an exemplary integrated frame member of the present application; 
         FIG.  20    is an alternative commissure post; 
         FIG.  21    is a tubular legs of fabric used to cover the separate commissure posts; 
         FIGS.  22 A and  22 B  are perspective views of a cloth-covered commissure post secured to an outflow edge of a cloth-covered anchoring frame member; 
         FIG.  23    illustrates alternative commissure posts, and  FIG.  24    shows one alternative commissure post secured to an outflow edge of a cloth-covered anchoring frame member; 
         FIGS.  25 A- 25 D  are perspective, elevational, and flat plan views of an exemplary integrated frame member for use in the hybrid prosthetic heart valves disclosed herein; 
         FIGS.  26 A- 26 D  are several views of an alternative integrated frame member much like that shown in  FIGS.  25 A- 25 D  but with commissure posts that are separated from a lower expandable frame; 
         FIGS.  27 A and  27 B  are perspective and elevational views of a still further integrated frame member of the present application that is non-collapsible and non-expandable; 
         FIGS.  28 A and  28 B  are perspective and elevational views of another integrated frame member with separate commissure posts; 
         FIG.  29    is a perspective view of an alternative integrated frame member having an expandable frame connected to a polymer band that forms commissure posts; 
         FIGS.  30 A and  30 B  are elevational and perspective views of an exemplary expandable frame for use in the frame member of  FIG.  29   ; and 
         FIG.  31    is an elevational view of an integrated frame member similar to that shown in  FIG.  29    with the polymer band overlapping an upper edge of the expandable frame. 
     
    
    
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS 
     The prosthetic heart valves disclosed herein are “hybrid” in that they include a prosthetic valve member with a relatively stable diameter, and a lower expandable frame structure to help in anchoring the valve in place. Most prior valves have either a wholly non-compressible/non-expandable valve member or a wholly expandable frame structure that incorporates a valve therein. One specific commercial prosthetic heart valve that is constructed in a hybrid manner is the Edwards Intuity® valve system from Edwards Lifesciences of Irvine, Calif. The hybrid Edwards Intuity® valve system comprises a surgical non-compressible/non-expandable valve member (e.g., Edwards  Magna  Ease® valve) having bioprosthetic (e.g., bovine pericardial) leaflets coupled to a stainless steel expandable frame structure on its inflow end. 
       FIGS.  1 - 7    illustrate a number of steps in the construction of an exemplary hybrid prosthetic heart valve  20 . 
       FIG.  1 A  is an exploded view of an inner structural band subassembly  40 , and  FIG.  1 B  shows the band subassembly having been covered with cloth and exploded over a peripheral sealing ring. The inner structural band subassembly  40  includes an inner polymer band  42  having three upstanding posts  44  and a scalloped lower ring  46 , and an outer more rigid band  48  having a scalloped shape to conform to the lower ring  46 . The band subassembly  40  is formed by positioning the polymer band  42  within the rigid band  48  and securing them together with sutures through aligned holes, for example. 
       FIG.  1 B  is a perspective view of the assembled band subassembly  40  covered in cloth exploded from a sewing ring  68 . The two structural bands  42 ,  48  are the same heights in the cusp region and encompassed by a fabric cover  64  that is rolled into a peripheral tab  66 . As seen in  FIG.  1 D , the sewing ring  62  comprises an inner suture permeable member  68  having a frustoconical form and encompassed by a second fabric cover  70 . Two fabric covers  64 ,  70  are sewn together at a lower junction point  72  to form the cloth-covered assembly of  FIG.  1 C , while  FIG.  1 D  shows details through a cusp portion thereof. 
       FIG.  2 A  is a perspective view of a flexible leaflet subassembly and  FIG.  2 B  shows an undulating wireform used for support thereof.  FIG.  2 C  is a perspective view of a cloth-covered wireform subassembly  50 , and  FIG.  2 D  is a detailed sectional view of a cusp portion of the wireform  50  showing an inner wire member  52  covered with fabric that defines a tubular portion  54  and an outwardly projecting flap  56 . The wireform  50  defines three upstanding commissure posts  58  and three downwardly convex cusps  60 . This is a standard shape for tri-leaflet heart valves and mimics the peripheral edges of the three native aortic leaflets. The shape of the wireform  50  coincides with the upper edge of the band subassembly  40 , and defines the outflow edge of the prosthetic valve  20 . The wireform subassembly  50  is then joined together with the flexible leaflet subassembly, as seen in  FIG.  2 E . 
       FIG.  3    is a perspective view of a finished valve member including the combination of the subassemblies shown in  FIGS.  1 C and  2 E . 
       FIGS.  4 A and  4 B  are inflow and outflow perspective views, respectively, of the surgical heart valve member  24  before coupling with an inflow anchoring skirt to form the hybrid heart valve  20 . Although construction details are not shown, three flexible leaflets  74  are secured along the undulating wireform  50  and then to the combination of the band subassembly  40  and sewing ring  62  shown in  FIG.  1 C . In a preferred embodiment, each of the three leaflets includes outwardly projecting tabs that pass through the inverted U-shaped commissure posts  58  and wrap around the cloth-covered commissure posts  75  (see  FIG.  1 C ) of the band subassembly  40 . The entire structure at the commissures is covered with a secondary fabric to form the valve commissures  35  as seen in  FIG.  7 A . 
     One feature of the valve member  24  that is considered particularly important is the sewing ring  62  that surrounds the inflow end thereof. As will be seen, the sewing ring  62  is used to attach the anchoring skirt  26  to the valve member  24 . Moreover, the sewing ring  62  presents an outward flange that contacts an atrial side of the annulus, while the anchoring skirt  26  expands and contracts the opposite, ventricular side of the annulus, therefore securing the heart valve  20  to the annulus from both sides. Furthermore, the presence of the sewing ring  62  provides an opportunity for the surgeon to use conventional sutures to secure the heart valve  20  to the annulus as a contingency. 
     The preferred sewing ring  62  defines a relatively planar upper or outflow face and an undulating lower face. Cusps of the valve structure abut the sewing ring upper face opposite locations where the lower face defines peaks. Conversely, the valve commissure posts align with locations where the sewing ring lower face defines troughs. The undulating shape of the lower face advantageously matches the anatomical contours of the aortic side of the annulus AA, that is, the supra-annular shelf. The ring  62  preferably comprises a suture-permeable material such as rolled synthetic fabric or a silicone inner core covered by a synthetic fabric. In the latter case, the silicone may be molded to define the contour of the lower face and the fabric cover conforms thereover. 
     Now with reference to  FIGS.  5  and  6   , assembly of the cloth-covered anchoring skirt  26  will be described.  FIG.  5    is an exploded assembly view of a portion of a cloth-covered anchoring skirt for coupling to the valve member, and  FIG.  6    is an exploded assembly view of the portion of the cloth-covered anchoring skirt shown in  FIG.  5    and a lower sealing flange secured thereto to form the inflow anchoring skirt. It should first be noted that the size of the anchoring skirt  26  will vary depending on the overall size of the heart valve  20 . Therefore the following discussion applies to all sizes of valve components, with the dimensions scaled accordingly. 
     The general function of the anchoring skirt  26  is to provide the means to attach the prosthetic valve member  24  to the native aortic root. The anchoring skirt  26  may be a pre-crimped, tapered, 316L stainless steel balloon-expandable stent, desirably covered by a polyester fabric to help seal against paravalvular leakage and to promote tissue ingrowth once implanted within the annulus. The anchoring skirt  26  transitions between the tapered, constricted shape of  FIG.  5 B  to a flared, expanded shape. The anchoring skirt  26  comprises an inner stent frame  80 , a fabric covering  82 , and a band-like lower sealing flange  84 . The stent frame  80  assembles within a tubular section of fabric  82 , which is then drawn taut around the stent frame, inside and out, and sewn thereto to form the intermediate cloth-covered frame  88  in  FIG.  5   . During this assembly process, the stent frame  80  is desirably tubular, though later the frame will be crimped to a conical shape as see in  FIG.  7 B  for example. A particular sequence for attaching the tubular section of fabric  82  around the stent frame  80  includes providing longitudinal suture markers (not shown) at 120° locations around the fabric to enable registration with similarly circumferentially-spaced, commissure features on the stent frame. After surrounding the stent frame  80  with the fabric  82 , a series of longitudinal sutures at each of the three 120° locations secure the two components together. Furthermore, a series of stitches are provided along the undulating upper end  86  of the stent frame  80  to complete the fabric enclosure. In one embodiment, the tubular section of fabric  82  comprises polytetrafluoroethylene (PTFE) cloth, although other biocompatible fabrics may be used. Subsequently, the lower sealing flange  84  shown in  FIG.  6    is attached circumferentially around a lower edge of the intermediate cloth-covered frame  88 . 
       FIG.  7 A  shows the valve member above the cloth-covered anchoring skirt and schematically shows one method of couple the two elements using sutures.  FIG.  7 B  illustrates the inner plastically-expandable stent frame  80  with cloth covering removed to indicate a preferred pattern of coupling sutures passed therethrough. The anchoring skirt  26  preferably attaches to the sewing ring  62  during the manufacturing process in a way that preserves the integrity of the ring and prevents reduction of the valve&#39;s effective orifice area (EOA). Desirably, the anchoring skirt  26  will be continuously sutured to the ring  62  in a manner that maintains the contours of the ring. In this regard, sutures may be passed through apertures or eyelets  92  arrayed along the upper or first end  86  of the inner stent frame  80 . Other connection solutions include prongs or hooks extending inward from the stent, ties, hook-and-loop fasteners (e.g., Velcro® fasteners), snaps, adhesives, etc. Alternatively, the anchoring skirt  26  may be more rigidly connected to rigid components within the prosthetic valve member  24 . 
     The construction steps described above in  FIGS.  1 - 7    are relatively detailed and time-consuming. Current hybrid valves such as described above take 11-12 hours total to build. This includes building a valve member, as in  FIGS.  1 - 3   , which takes approximately 7.5 hours, and then covering the stent frame  80  with cloth and attaching it to the valve member, which combined take another 3-4 hours of time. It would therefore be desirable to reduce the labor hours to build such a valve. 
     Moreover, the aforementioned hybrid valve system does not have expandability during a valve-in-valve (ViV) procedure due to both the relatively rigid band subassembly  40  as well as the anchoring stent frame  80 . Some attempts at making prosthetic valves expandable for ViV are known, but the resulting valve is expensive and difficult to build. Consequently, the present application discloses a number of configurations of hybrid valves and methods of making that simplify the assembly and result in a ViV-adapted hybrid valve. 
       FIGS.  8 A- 8 C  illustrate a hybrid prosthetic heart valve  170  of the present application, which includes an upper valve member  172  coupled to a cloth-covered anchoring skirt  174 .  FIG.  8 B  shows the valve member  172  in phantom to illustrate the contours of an expandable frame  176  of the anchoring skirt  174 , and  FIG.  8 C  is a perspective view of the entire heart valve  170  with portions at one commissure post  178  cutaway to reveal internal structural leaflet supports. 
     The valve member  172  of the hybrid prosthetic heart valve  170  shares some structural aspects with the prior art valve member illustrated in  FIG.  3   . In particular, there are three upstanding commissure posts  178  alternating with three arcuate cusps  180  curving in an inflow direction. Three flexible leaflets  182  are supported by the commissure posts  178  and cusps  180  and extend across a generally cylindrical flow orifice defined therewithin. The leaflets  182  are attached to an up and down undulating typically metallic wireform  184  via a cloth covering. As with earlier valve constructions, the upstanding posts  186  rise up adjacent to and just outside of the commissures of the wireform  184 , and outer tabs  188  of the leaflets  182  extend underneath the wireform, wrap around the posts, and are secured thereto with sutures. 
     In the illustrated embodiment, the heart valve  170  also includes a highly compliant sealing ring  190  extending outward therefrom at approximately the interface between the valve member  172  and the anchoring skirt  174 . The sealing ring  190  as well as the expandable frame  176  are covered with a fabric  192  that helps prevent leakage around the outside of the valve once implanted. Furthermore, the sealing ring  190  is also suture-permeable and may be used to secure the valve in place in the native annulus. 
       FIGS.  9 A- 9 C  illustrate details of the exemplary expandable frame  176  for use in the hybrid prosthetic heart valve  170  of  FIGS.  8 A- 8 C . 
     With specific reference to  FIG.  9 A , the lower frame  176  is shown in perspective and includes a plurality of circumferential row struts connected by a series of spaced axial column struts. Specifically, an upper or outflow row strut  200  extends continuously around a periphery of the frame  176 , and preferably follows a gently undulating path so as to match a similar shape of the underside of the upper valve member  172  ( FIG.  8 B ). As seen in  FIG.  9 A , three peaks  204  along the upper row strut  200  correspond to the locations of the commissures  178  of the valve  170 . In general, the lower frame  176  attaches to an inflow end of the upper valve member  172 , and preferably directly to or to fabric covering the internal support frame. The lower frame  176  is initially generally tubular and expands to be somewhat conical with the free end farthest from the upper valve member  172  expanding outward but the end closest remaining the same diameter. 
     The upper row strut  200  includes a plurality of eyeholes  202  evenly spaced apart and located just below the top edge thereof that are useful for securing the frame  176  to the fabric of the underside of the valve member  172 . A series of axial column struts  206  depend downward from the upper row strut  200 , and specifically from each of the eyeholes  202 , and connect the upper row strut to two lower row struts  208 . The lower row struts  208  circumscribe the frame  176  in zig-zag patterns, with an inverted “V” shape between each two adjacent column struts  206 . The lower row struts  208  preferably traverse horizontally around the frame, and the length of the column struts  206  thus varies with the undulating upper row strut  200 . 
     As mentioned above, the lower frame  176 , in particular the inflow end thereof, may be plastically expanded, such as by balloon expansion, and may be formed of a plastically expandable material, for example, stainless steel or cobalt-chromium (e.g., Elgiloy® alloy). Alternatively, the lower frame  176  may be self-expanding, such as being formed from nitinol. In a conventional Edwards Intuity® valve, the upper row strut  200  is generally ring-like without capacity for compression or expansion. In the illustrated frame  176 , on the other hand, a series of spaced notches  210  are provided that permit expansion and contraction. That is, circumferential segments of the strut  250  are interrupted by the V-shaped notches  210  that permits a limited amount of expansion, perhaps 3 mm in diameter, to accommodate a supplemental expandable valve to be inserted and expanded therein. More particularly, the upper row strut  200  (outflow end) of the frame  176  defines a nominal diameter seen in  FIG.  9 A  that enables functioning of the valve member  172 . The upper row strut  200  is radially compressible from the nominal diameter to a smaller contracted diameter to enable compression of the outflow end of the frame  176  during delivery of the heart valve. The upper row strut  200  is also radially expandable from the nominal diameter to a larger expanded diameter upon application of an outward dilatory force from within the stent frame such as in a valve-in-valve procedure. 
     It should be understood that the preferred embodiment of the hybrid prosthetic heart valve  170  is configured for surgical delivery, which differs from transcatheter or transapical delivery. In the latter cases, prosthetic heart valves are formed of structures and materials that enable substantial compression of the valve into a relatively small diameter profile, to enable delivery through the vasculature (e.g., transcatheter) or directly into the heart through an introducer (e.g., transapical). The hybrid prosthetic heart valve  170 , on the other hand, is typically delivered via open heart surgery or a less invasive version thereof, such as through a mid-thoracotomy. “Surgical” delivery of heart valves requires that the heart be stopped and the patient be placed on cardiopulmonary bypass, while transcatheter and transapical procedures may be done on a beating heart. Therefore, the hybrid prosthetic heart valves  170  disclosed herein are only compressible to a limited degree, to enable a smaller delivery profile, but not totally compressible. 
     As shown in  FIG.  9 B , the modified frame  176  can be collapsed to a pre-determined minimum diameter for delivery and expanded to a pre-determined maximum diameter during a valve-in-valve procedure. More specifically, the upper row strut  200  of the illustrated frame  176  may be collapsed by 2 mm relative to the nominal diameter for ease of delivery by compressing the V-shaped notches  210  as indicated. Because the notches  210  can only be compressed until the two corners meet, the frame  176  can only be collapsed by a predetermined amount. The exemplary frame  176  is specifically designed to be collapsible to ease insertion through small incisions when the valve is implanted and for ease of seating in the annulus. The amount of collapse could be as large as about 40-50% by diameter, but would more preferably be about 2-3 mm, or between about 7-20% for heart valves having nominal operating diameters between about 19-29 mm. A compression of 2 mm in diameter, for example, corresponds to a change in circumference of about 6.28 mm. The stent frame is divided into 18 segments around its circumference by the axial column struts  206 . Therefore, by placing an initial gap of 0.35 mm (6.28 mm/18) in each segment, the frame can collapse by 2 mm in diameter before adjacent segments make contact and hence prevent further compression. 
       FIG.  9 C  discloses that the upper row strut  200  of the illustrated frame  176  may be subsequently expanded by up to 3 mm relative to a nominal diameter during a valve-in-valve procedure. Because of the configuration of the upper row of struts, the outflow portion of the frame cannot be expanded more than 3 mm. That is, the V-shaped notches  210  eventually straighten out, which prevents further expansion. Desirably, the frame is designed to expand 3 mm in diameter beyond its nominal diameter. The nominal diameter is defined when the notches  210  are V-shaped, prior to either contraction or expansion. Similar to the gaps for limiting compression, the 3 mm in expansion corresponds to an about 9.42 mm (3 mm×n) change in circumference. Therefore, each of the 18 segments limits expansion to 9.42 mm/18=about 0.52 mm. In this example, the length of the “V” shaped struts connecting each segment are thus 0.52 mm+0.35 mm (from the compression gaps)=0.87 mm During a valve-in-valve expansion, the expansion of the stent frame would be limited by the expansion-limiting struts at the point where they became straight across the gap between adjacent frame segments. 
     If it is not desired to have the frame collapsible but expansion is still desired, the gaps could be reduced to the practical limit of laser cutting, for example, about 25 μm. With 18 gaps of 25 μm, the total amount of compression would be (18×25 μm/n)=0.143 mm (about 0.006″). 
     In contrast, some earlier designs simply removed the upper row of struts that defines the outflow diameter of the frame. Such a frame configuration had no built-in way to limit the maximum expansion of the valve during a valve-in-valve procedure. Additionally, there could be an advantage to having hybrid valves that are collapsed by a limited amount, for example, about 2-3 mm, for easier insertion. While a frame without an upper row of struts could be collapsed, there is no built-in limit the amount of compression. It might be desirable to have the maximum compression amount limited as disclosed herein for consistency and for preventing physicians from trying to collapse the valve more than it can safely be collapsed. 
     In addition, a number of valve-type indicators  212  are integrated into the frame  176  at locations around its circumference, such as three valve size indicators. In the illustrated embodiment, the valve size indicators  212  comprise small plate-like tags inscribed with the numerical valve size in mm, for example 21 mm in the illustrated embodiment. The use of any alphanumeric characters and/or symbols that signify size or other feature of the valve are contemplated. The frame  176  may be laser cut from a tubular blank, with the plate-like size indicators  212  left connected to one more of the struts. As shown, the size indicators  212  are located just below the peaks  204  of the undulating upper row strut  200 , connected between the corresponding eyehole  252  and the descending column strut  206 . There are thus three size indicators  212  spaced about 120° apart around the frame  176 . This location provides additional space between the upper row strut  200  and the adjacent lower row strut  208 . The inscribed or cutout valve size numerals are sufficiently large to be visualized with X-ray, Transesophageal Echocardiogram (TEE), or other imaging modality. In one embodiment, the valve size numerals are from about 1.5 mm to about 2 mm in height, for example, about 1.75 mm in height. 
       FIG.  10 A  is an exploded perspective view of components of an alternative hybrid prosthetic heart valve  300 . The alternative heart valve  300  does away with an internal stent or support frame previously shown as the composite bands  42 ,  48  in  FIG.  1 A , for example. The composite band structure was the primary source of circumferential rigidity to the heart valves in which they were employed, and thus an expansion structure enabled valve-in-valve procedures. The alternative hybrid heart valve  300  includes a lower compressible/expandable frame  302 , as before, separate commissure posts  304  that are secured to the frame, and an undulating wireform  306  supporting flexible leaflets  308 , also as before. 
       FIG.  10 B  shows a subassembly  310  including the wireform  306  juxtaposed with the three leaflets  308 , and an “integrated” subassembly  312  of the expandable frame  302  with the commissure posts  304  attached thereto. Each of the flexible leaflets  308  has two tabs  309 , and pairs of tabs on adjacent leaflets are shown projecting through (under) the inverted V-shaped commissures of the wireform  306 . These pairs of tabs  309  then wrap around one of the upstanding commissure posts  304  of the subassembly  312 , which are located adjacent to and radially outward from the wireform commissures. The subassemblies  310 ,  312  are eventually covered with biocompatible fabric such as polyester, and the pairs of tabs  309  and commissure posts  304  are secured to each other with a cloth covering (see  FIG.  13   ). 
     Due to the attachment of the commissure posts  304  to the frame  302  the subassembly  312  integrates the frame and commissure posts, while as described below, an “integrated” frame may mean that the commissure posts are integrally formed of the same homogeneous material as the rest of the stent frame. Integrated in this sense meaning the two components are securely attached together prior to assembly with the wireform/leaflet subassembly  310 , either by securing the two parts or forming them at the same time from the same material. Furthermore, a hybrid heart valve with an “integrated” frame means that the frame provides both the expandable skirt frame as well as commissure posts to which the leaflets attach, without any additional structural bands, such as the metal band  48  seen in  FIG.  1 A . With this configuration, the number of parts in the valve is reduced, which reduces assembly time and expense. 
       FIGS.  10 C and  10 D  illustrate a commissure post  304  from an outer and an inner perspective, respectively. A lower end of each of the commissure posts  304  includes a concave ledge  314  that matches the contour of one of the peaks  316  in the undulating upper row of struts  318  of the expandable frame. As seen in  FIG.  10 B , an outer plate  320  below each of the concave ledges  314  of the commissure posts  304  extends downward on the outside of the expandable frame  302 . Sutures  322  secure the commissure posts  304  to the frame  302  via suture holes  324  that align with eyeholes  326  at the peaks  316  of the undulating upper row strut  318 . This shape matching followed by covering with fabric provides a relatively stable arrangement of the commissure posts  304  in the integrated frame subassembly  312 . 
       FIG.  11    is another exploded perspective view of subassemblies of the alternative hybrid prosthetic heart valve  300 . In this view, the wireform in the subassembly  310  of the wireform and leaflets has been covered with fabric, and features an outwardly projecting flap  330 . The fabric flap  330  is used to secure the wireform/leaflet subassembly  310  to the subassembly  312  of the expandable frame  302  and commissure posts  304 . Furthermore, a suture-permeable sealing ring  332  may be attached such as by sewing at the juxtaposition between the two subassemblies  310 ,  312 . 
     The relative positions of the wireform  306  and the frame/commissure post subassembly  312  is seen in  FIG.  12   , and also in further detail in  FIGS.  12 A- 12 D , with the commissure posts  304  immediately outside of the commissures of the wireform  306 . Finally,  FIG.  13    is a perspective view of the finished hybrid prosthetic heart valve  300  entirely covered with fabric. 
     The removal of the aforementioned stent bands and attachment (integration) of the commissure posts  304  directly to the frame  302  greatly simplifies construction, reduces labor hours, lowers the radial profile of the valve by ˜1.6 mm, and allows for expansion during a valve-in-valve procedure. A preferred construction sequence involves attaching the sealing ring  332  to the expandable frame  302 , along with three cloth-covered commissure posts  304 , then attaching this assembly to the wireform/leaflet subassembly  310  during final assembly. 
     The commissure posts  304  disclosed have specific features that interface with the frame  304  to add stability to the posts in all directions. That is, the specific surfaces  314 ,  320  that mate with the corresponding peaks  316  on the frame  302  as well as the holes  324  that allow the posts to attach with sutures  322  to the frame provide excellent stability in all directions for subsequent covering with fabric. The commissure posts  304  could be molded from polyester or some other biocompatible material into the shape shown here, or even produced using 3D printing. 
     A hybrid valve  340  built using the disclosed methods is shown in  FIGS.  14 A and  14 B  with all but flexible leaflets  342  covered with cloth. The improved valve construction disclosed herein eliminates a separate stent subassembly by combining the functions of that assembly (supporting the leaflets from underneath as well as from the sides in the commissure area, and attachment of the sewing ring insert) with the stent frame assembly. As will be explained, the main components of the hybrid valve  340  include a wireform  344  having alternating cusps and commissures that supports the leaflets  342 , a lower expandable frame  346  integrated with commissure posts  348 , and preferably a sealing ring  350  around the periphery of the cusps of the wireform  344 . Several steps in the assembly process will now be described. 
       FIG.  15 A  shows the first step in the disclosed method of hybrid valve construction. A piece of PTFE tubular cloth  352  is first partially inverted and placed over the generally tubular stent frame  346  from the bottom, thus covering the inside, outside, and bottom of the frame. Subsequently, the cloth  352  is sewn to the frame  346  through frame holes and around a top circumferential row of struts  354  using an in-and-out stitch with double PTFE thread.  FIG.  15 B  shows the cloth  352  pulled back on the inside and outside after sewing is complete, thereby exposing the top of the stent frame  346 . More particularly, the top circumferential row of struts  354  is left partly exposed; at least three peaks intermediate three valleys of the undulating row. 
       FIG.  16 A  shows the stent frame  346  covered in the cloth  352  and with a sewing ring insert  356  placed adjacent the top row of struts  354 . The cloth layers below the sewing ring  356  have been rough cut, which is acceptable as they are subsequently covered in an outer layer of cloth, thus eliminating the need to “finish” the PTFE cloth in that area. An alternative method would be to fold those layers and finish them on either the top or bottom of the sewing ring. 
     In  FIG.  16 B , the sewing ring insert  356  has been stitched to the top of the stent frame  346  in  6  locations to give it a desired scalloped shape. Six locations would be a minimum to define the high (commissures) and low (cusp centers) points of its desired shape. It could be attached at more locations to better define its shape. The PTFE cloth  352  from the inside of the stent frame  346  has been inverted over the sewing ring insert  356  and formed by hand to follow the scalloped shape of the insert. Subsequent to conforming the cloth to the insert as shown, both the inner and outer layers of cloth are sewn together (between the stent frame and the insert). 
     After the sewing ring formation as shown in  FIG.  16 B , the next step is to cover three polymer (e.g. PET) commissure tip inserts  360 , shown in  FIG.  17   , with cloth  361 , as shown in  FIG.  18   . Because these inserts  360  are simple 2D parts, they could potentially be sewn on a machine, or “socks” could be knitted to fit over them. Another option could be to use a different cloth, such as PET-based cloth, which could be laser cut and fused to make the covers for the inserts. 
       FIGS.  19 A and  19 B  shows how the inserts  360  sit with respect to the stent frame  346  and outside of the commissures  362  of a wireform  364 . The cloth is not shown in the sketch. The inserts  360  sit directly over the peaks of the upper row of struts  354  of the stent frame  346 . The tip inserts  360  and stent frame  346  could be sewn together through holes  366  in the stent frame and a lower hole  368  in the inserts, through their respective layers of cloth. This provides a high degree of vertical stability to the commissures of the assembly.  FIGS.  19 A and  19 B  show two different patterns for the holes  368  in the inserts  360 , two or three toward the lower end, while  FIGS.  17  and  18    show a single hole. Of course, other arrangements are contemplated. 
     After the cloth-covered commissure inserts  360  are attached to the stent frame/sewing ring assembly, final assembly would be performed. Final assembly would include stitches from below the sewing ring insert  356  (see  FIG.  16 A ) through its hinge point, through the leaflets and wireform cloth, then down through all layers as an in-and-out stitch. 
     One method of creating commissure inserts uses a polyester (or other material) tip piece  363 , similar to that used in the Carpentier-Edwards Model 2700 heart valve, as shown in  FIG.  20   . The tip piece  363  would have at least one hole  365  in the bottom to facilitate attachment to the expandable stent frame after cloth covering, as well as other holes for securing the cloth, and securing the insert to the wireform cloth. 
       FIG.  21    shows an example of a PET tubular cloth  366 , which could be used to cover the component shown in  FIG.  20   . The ends of the tube can be knitted closed, as is done on prior art annuloplasty rings, or fused closed with ultrasonic, laser, or heat methods. With one end closed, the piece  364  from  FIG.  20    can be inserted from an open end. The cloth  366  can then be folded over to form multiple layers on one side tip piece for subsequent leaflet attachment. 
       FIGS.  22 A and  22 B  show a commissure insert  368  made in the fashion attached to a cloth-covered expandable stent frame described above. Three such commissure inserts would be attached to the cloth-covered stent frame, which would then be ready for final assembly with the wireform-leaflet assembly. A second method of making commissure inserts uses a non-woven fabric such as Reemay® spunbonded polyester. 
       FIG.  23    shows solid fabric inserts  370  made in this manner. The inserts  370  can simply be die (or laser, etc.) cut from non-woven fabric sheet of the desired thickness and porosity. These inserts  370  would be immediately ready to attach to the cloth-covered stent frame  372  as shown in  FIG.  24   . As an alternative to making them from a homogenous sheet, they could be made from a composite that had, for example, a very dense and stiff layer that could face the inside of the valve to add support and minimize leakage, and a less dense layer on the outside that would be easy to stitch to during final valve assembly. For even more stiffness, the composite could contain a layer of polyester sheet, either inserted into a pocket cut into a single, thick section of fabric, or as a layer in a composite structure. 
       FIGS.  25 - 31    illustrate alternative integrated anchoring skirt and commissure post subassemblies. As described above with respect to  FIGS.  10 - 13   , the subassembly  312  shown in  FIG.  10 B  eliminates the need for annular structural bands, which bands provide stability and rigidity but which impede the ability of the valve to expand post-implant. Each of the alternative subassemblies shown in  FIGS.  25 - 31    also eliminate the need for the structural bands, and further integrate the anchoring skirt and the commissure posts. 
       FIG.  25 A  shows a still further assembly  400  of the structural components of a hybrid prosthetic heart valve having an integrated frame member  402  much like those described above but formed of a single piece. A schematic wireform  404  is shown situated on top of the frame member  402  in  FIG.  25 A , with flexible leaflets and a cloth cover not shown and representing a wireform/leaflet subassembly such as shown at  310  in  FIG.  11   . The schematic wireform  404  is shown with an outwardly extending sewing flange  406 , which may be formed by joined lengths of two fabric tabs that wrap around and cover the wireform. When covered with cloth, the frame member  402  serves as the supportive component for the wireform, leaflets and sealing ring. Further, when covered with cloth, the frame member  402  provides an effective seal against paravalvular leaking (PVL) and circumferential stability to the valve. 
     The integrated frame member  402 , which is also shown in  FIGS.  25 B- 25 D , comprises a lower expandable skirt portion  410 , an upper annulus band  412 , and leaflet support posts  414 . The skirt portion  410  comprises a number of chevron patterned or V-shaped struts that can be easily crimped and then expanded. The annulus band  412  provides real estate for the attachment of a sealing ring (not shown), and preferably includes a series of holes around its circumference through which to pass sutures connecting the sealing ring. The integrated frame member  402  includes multiple cuts that enable post-implant expansion and may be laser-cut from a suitable metal such as Elgiloy and electro-polished. 
     The frame member  402  is desirably formed from a tubular blank of a suitable material, and has a generally circular inflow or lower edge and an undulating outflow or upper edge. More particularly, the upper edge defines three arcuate cusp portions  416  intermediate three upstanding commissure posts  418 . The undulating upper edge is shaped to closely fit underneath the wireform  406 . After assembling the frame member  402  with the rest of the heart valve components, the skirt portion  410  is typically crimped in a generally conical manner such that its lower edge has a smaller diameter than its upper edge. 
     Compression/expansion sections  420  along the annulus band  412  are also added to enable a limited collapse of the frame member  402  during delivery. The compression/expansion sections  420  comprise slits formed in the upper edge of the frame member  402  that have spaces enabling a limited compression, and also permit expansion. In a preferred embodiment, solid segments  422  spaced around the annulus band  412  are connected by thin inverted U-shaped bridges  424 . 
     As seen in  FIG.  25 D , the frame member  402  further includes a number of slits in the region of the commissures  418  to facilitate expansion in general flexibility of the frame member. An elongated central slit  426  extends nearly the entire height of each of the commissures  418 . Regions of expandable circumferential struts  428  are positioned within the skirt portion  410  axially aligned with both the compression/expansion sections  420  and the central slits  426 . When an outward radial force is applied from within the heart valve having the frame member  402 , the annulus band  412  permits expansion because of both the sections  420  and slits  426 . Additionally, short arcuate slits  430  are formed at the base of each of the commissure posts  418 , generally following a truncated undulating line joining the cusp portions  416 . These slits  430  reduce the radial stiffness of the posts  418  such that most of the physiological load absorbed by the flexible leaflets is transferred to the wireform  406 , rather than to the posts. 
     Despite the arcuate slits  430  in the frame member  402  of  FIGS.  25 A- 25 D , there are concerns that such an integrated frame design will stiffen the wireform commissure post area, thus altering the load carry mechanism of proven valve platforms. To alleviate such concerns, the three commissure posts may be made of three separate pieces, preferably using polymeric material, such that when connected with the underlining metal frame with sutures, there will not be metal to metal contact. 
     For instance,  FIGS.  26 A- 26 D  illustrate an alternative frame member  440  that is configured about the same as the frame member  402 , but has separate commissure posts  442 . The frame member  440  is shown situated just below a wireform assembly  441  in  FIG.  26 A . As seen in  FIGS.  26 C- 26 D , the annulus band region  444  and the in-flow strut region  446  are exactly same as that of the frame member  402 . The only difference is separate commissure posts  442  preferably made of plastic material that will be sewn together with the frame member  440  using sutures  448  before being covered with cloth. A pair of attachment holes  450  is desirably formed in each of the commissure posts  442  for this purpose. As before, the crimpable and expandable frame member  440  without commissure posts is laser-cut and electropolished. 
     Although the ability to compress and expand the frame members may be an advantage, the present application also contemplates integrated frame members for a hybrid prosthetic heart valves that are not either expandable or compressible.  FIGS.  27 A- 27 B  show an assembly  460  of the structural components of a hybrid prosthetic heart valve including an integrated frame member  462  with a lower expandable skirt portion  464 , an upper annulus band  466 , and leaflet support posts  468 . The annulus band  466  provides real estate for the attachment of a sealing ring (not shown). As before, the integrated frame member  462  may be laser-cut from a suitable metal tube such as Elgiloy and electro-polished. A wireform  470 , such as in the subassembly  310  in  FIG.  11   , is illustrated just above the undulating upper end of the frame member  462 , with flexible leaflets and a cloth cover not shown for clarity. 
     As seen best in  FIG.  27 B , the frame member  462  has an outflow or upper edge  472  without capacity for either compression or expansion. That is, a plurality of solid segments  474  spaced around the annulus band  462  are connected by small solid bridges  476 . Each of the solid segments  474  preferably has a through hole  478  for use in an attaching a sewing ring around the periphery thereof. 
       FIG.  28 A  shows another assembly  480  of the structural components of a prosthetic heart valve including a non-compressible, non-expandable integrated frame member  482  much like the one in  FIGS.  27 A- 27 B , but with separated commissure posts  484 . Several suture holes  486  in the commissure posts are also added to help secure the commissure posts  484  to an annulus band  488  of the frame member  482 , much like is shown in  FIG.  26 A . 
       FIG.  25 A  is a fully integrated frame member  402 , with concerns over stiffened commissure posts. The frame member  442  shown in  FIG.  26 A  alleviated that concern with three separate commissure posts  442 , but those require sewing together with the expandable frame, which increases the time and steps when assembling the valve. In order to preserve the same load bearing characteristics of the existing commercial valve platforms, while still having a relative easy valve assembly procedure, the embodiments shown in  FIGS.  29  and  31    are also contemplated. 
       FIG.  29    shows an assembly  500  that includes an expandable frame  502  much like the frame  176  described above with respect to  FIG.  9 A . The frame  502  is secured via sutures to a stent band  504  with upstanding commissures  506  to form an integrated frame member. This stent band  504  is essentially the inner band  95  from  FIG.  1 A , with suture holes  505  around its circumference to enable secure attachment to the top row of struts of the frame  502 . An upper row of struts  508  includes regularly spaced compressible/expandable segments  510  to enable pre-implant compression, and post-implant expansion during a valve-in-valve procedure. 
     The assembly  500  is again crimpable and expandable. The stent band  504  is formed of a polymer (e.g., polyester) material that is breakable when in expansion force is applied within the valve. This makes the whole valve expandable for valve-in-valve applicable. Because of the polymer commissures  506 , the valve load carrying characteristics will be exactly the same as the existing commercial valve platform, thus hydrodynamic performance and durability of the valve shall be the same as the existing commercial valve as well. The relative position of the polyester band and the expandable frame can be assembled as illustrated in  FIG.  29   , with the stent band  504  positioned immediately above the frame member  502 . Conversely, as seen in  FIG.  31   , the stent band  504  may be located partly radially within the frame  502 , in an overlapping manner. This aligns the series of through holes  505  in the stent band  504  with eyeholes  512  provided in the frame  502 , which greatly facilitates assembly, thus reducing time and expense. 
     Some Improvements Over Existing Designs: 
     1. Integrate the metal stiffener band, the stent frame and/or the polyester band together. 
     2. The commissure posts, the sewing ring section, as well as the chevron patterned strut section are expandable such that they expand uniformly without distorting the wireform. 
     3. Reduce the radial stiffness compared with the current heart valve frames so that a transcatheter valve balloon/frame can push the new valve open at least about 2 mm. 
     4. Integrated commissure posts for holding the leaflet tabs impose reduced or minimal forces on the leaflet, with most of the forces transferred to the wireform 
     5. No leakage path through the commissure post areas or the sewing ring attachment area. 
     6. Ease of locating and sewing/clipping/inserting the sewing ring on the frame. 
     7. During the crimping, expansion, and other manufacturing steps, the frame does not buckle/remains stable, especially at the commissure posts. 
     8. Crimpability at the annulus region reduces the profile of the valve during valve insertion. 
     Some Advantages: 
     1. Expandable hybrid prosthetic heart valves permit valve-in-valve procedures, improving valve performance. 
     2. Integrated design simplifies assembly, reducing labor and material costs. 
     3. Crimping the valve reduces its profile, which improves visibility during valve insertion and deployment, enhancing the user&#39;s experience. 
     While the disclosure references particular embodiments, it will understood that various changes and additional variations may be made and equivalents may be substituted for elements thereof without departing from the scope or the inventive concept thereof. In addition, many modifications may be made to adapt a particular situation or device to the teachings herein without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed herein, but includes all embodiments falling within the scope of the appended claims.