Patent Publication Number: US-11382740-B2

Title: Collapsible-expandable prosthetic heart valves with structures for clamping native tissue

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/545,481, filed Aug. 20, 2019, which is a continuation of U.S. patent application Ser. No. 14/688,357, filed Apr. 16, 2015, now U.S. Pat. No. 10,426,604, which is a continuation of U.S. patent application Ser. No. 11/906,133, filed Sep. 28, 2007, now U.S. Pat. No. 9,532,868, the disclosures of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to prosthetic heart valves, and more particularly to prosthetic heart valves that can be collapsed to a relatively small size for delivery into a patient and then re-expanded to full operating size at the final implant site in the patient. 
     At present there is considerable interest in prosthetic heart valves that can be collapsed to a relatively small circumferential (or annular perimeter) size for delivery into a patient (e.g., through tubular delivery apparatus like a catheter, a trocar, laparoscopic instrumentation, or the like). This is of interest because it can help to make replacement of a patient&#39;s defective heart valve less invasive for the patient. When the prosthetic valve reaches the desired implant site in the patient, the valve is re-expanded to a larger circumferential (or annular perimeter) size, which is the full operating size of the valve. 
     Because of the interest in prosthetic heart valves of the above general type, improvements to valves of this type are always being sought. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with certain possible aspects of the invention, a prosthetic heart valve may include an annular structure that is annularly continuous and that has an annular perimeter that is changeable in length between (1) a first relatively small length suitable for delivery of the valve into a patient with reduced invasiveness, and (2) a second relatively large length suitable for use of the annular structure to engage tissue of the patient adjacent to the patient&#39;s native valve annulus and thereby implant the valve in the patient. The valve further includes a flexible leaflet structure attached to the annular structure. The annular structure may comprise an annular array of diamond-shaped cells. Upstream apex portions of at least some of these cells may be resiliently biased to deflect radially outwardly from at least some other portions of the annular structure, and downstream apex portions of at least some of these cells may also be resiliently biased to deflect radially outwardly from at least some other portions of the annular structure. As a result, when the valve is in use in a patient, tissue of the patient adjacent to the patient&#39;s native heart valve annulus is clamped between the upstream and downstream apex portions, with the upstream apex portions engaging tissue upstream from the annulus, and with the downstream apex portions engaging tissue downstream from the annulus. 
     In accordance with certain other possible aspects of the invention, a prosthetic aortic heart valve may include an annular structure that is annularly continuous and that has an annular perimeter that is changeable in length between (1) a first relatively small length suitable for delivery of the valve into a patient with reduced invasiveness, and (2) a second relatively large length suitable for use of the annular structure to engage tissue of the patient adjacent to the patient&#39;s native aortic valve annulus and also downstream from ostia of the patient&#39;s coronary arteries to thereby implant the valve in the patient. The annular structure may include an annularly continuous annulus portion adapted for implanting adjacent the patient&#39;s native aortic valve annulus upstream from the ostia of the patient&#39;s coronary arteries, and an annularly continuous aortic portion adapted for implanting in the patient&#39;s aorta downstream from those ostia. The annulus portion and the aortic portion are preferably connected to one another only by a plurality of linking structures that are disposed to pass through at least a portion of the patient&#39;s valsalva sinus at locations that are spaced from the ostia of the patient&#39;s coronary arteries in a direction that extends annularly around the valsalva sinus. The valve further includes a leaflet structure that is attached to the annulus portion. The annulus portion includes first and second tissue clamping structures that are spaced from one another along an axis that passes longitudinally through the valve, each of the clamping structures being resiliently biased to extend radially outwardly from the leaflet structure, whereby, in use, tissue of the patient adjacent to the patient&#39;s native aortic valve annulus is clamped between the first and second clamping structures, with the first clamping structure engaging tissue upstream from the annulus, and with the second clamping structure engaging tissue downstream from the annulus. 
     In accordance with certain still other possible aspects of the invention, a prosthetic aortic heart valve includes an annular structure that is annularly continuous and that has an annular perimeter that is changeable in length between (1) a first relatively small length suitable for delivery of the valve into a patient with reduced invasiveness, and (2) a second relatively large length suitable for use of the annular structure to engage tissue of the patient adjacent to the patient&#39;s native aortic valve annulus and thereby implant the valve in the patient. The valve further includes a flexible leaflet structure attached to the annular structure. When a valve having these aspects of the invention is implanted in the patient, any non-leaflet part of the valve that is at the level of the patient&#39;s native coronary artery ostia is confined in a direction that is circumferential of the valve to areas that are adjacent to the patient&#39;s native aortic valve commissures or downstream projections of those commissures, each of said areas having an extent in the circumferential direction that is less than the distance in the circumferential direction between circumferentially adjacent ones of those areas. In addition, the annular structure includes first and second tissue clamping structures that are spaced from one another along an axis that passes longitudinally through the valve. Each of the clamping structures is resiliently biased to extend radially outwardly from the leaflet structure, whereby, in use, tissue of the patient adjacent to the patient&#39;s native aortic valve annulus is clamped between the first and second clamping structures, with the first clamping structure engaging tissue upstream from the annulus, and with the second clamping structure engaging tissue downstream from the annulus. 
     Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of some components of an illustrative prosthetic valve in accordance with the invention. 
         FIG. 2  is a simplified schematic diagram of a representative portion of apparatus like that shown in  FIG. 1  in relation to some native tissue structures of a patient in accordance with the invention. 
         FIG. 3  is generally similar to  FIG. 2  for some other native tissue structures of a patient. 
         FIG. 4  is a simplified elevational view of another illustrative embodiment of apparatus in accordance with the invention.  FIG. 4  shows the depicted apparatus in its collapsed/pre-expanded state, and as though cut along a vertical line and then laid out flat. 
         FIG. 5  is generally similar to  FIG. 4  for another illustrative embodiment in accordance with the invention. 
         FIG. 6  is a simplified elevational view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 7  is a simplified perspective view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 8  is a simplified perspective view showing an illustrative embodiment of another component added to what is shown in  FIG. 7  in accordance with the invention. 
         FIG. 9  is generally similar to  FIG. 8 , but shows an alternative embodiment with additional possible features in accordance with the invention. 
         FIG. 10  is generally similar to  FIG. 9 , but shows an illustrative embodiment of more components added to what is shown in  FIG. 9  in accordance with the invention. 
         FIG. 11  is a simplified perspective view showing in more detail a representative portion of the components that are added in  FIG. 10 . 
         FIG. 12  is a simplified perspective view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 13  is a simplified perspective view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 14  is a simplified elevational view of still another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 15  is generally similar to  FIG. 14 , but shows an illustrative embodiment of more components added to what is shown in  FIG. 14  in accordance with the invention. 
         FIG. 16  is a simplified elevational view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 17  is a simplified elevational view of another illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 18  is a simplified elevational view of another illustrative embodiment of a prosthetic heart valve in accordance with the invention. 
         FIG. 19  is a simplified perspective view of an embodiment like that shown in  FIG. 18  with other possible elements added in accordance with the invention. 
         FIG. 20  is a simplified elevational view of another illustrative of a prosthetic heart valve in accordance with the invention. 
         FIG. 21  is a simplified perspective view of another illustrative embodiment of a component for a prosthetic heart valve in accordance with the invention. 
         FIG. 22  is a simplified perspective view of another illustrative embodiment of a prosthetic heart valve in accordance with the invention. 
         FIG. 23  is a simplified perspective view of another illustrative embodiment of a prosthetic heart valve in accordance with the invention. 
         FIG. 24  is a simplified perspective view of another illustrative embodiment of a component for a prosthetic heart valve in accordance with the invention. 
         FIG. 25  is generally similar to  FIG. 24  for still another illustrative embodiment of a component for a prosthetic heart valve in accordance with the invention. 
         FIG. 26  is a simplified elevational view of yet another illustrative embodiment of a component for a prosthetic heart valve in accordance with the invention. 
         FIG. 27  is a simplified perspective view of still another illustrative embodiment of a prosthetic heart valve in accordance with the invention. 
         FIG. 28  is a simplified cross section of a typical patient tissue structure that is useful for explaining certain principles of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Certain components of an illustrative embodiment of a prosthetic heart valve  10  in accordance with the invention are shown in  FIG. 1 . Valve  10  is designed for use as a replacement for a patient&#39;s native aortic valve. (Other valve types will be considered later in this specification.)  FIG. 1  shows valve  10  in its expanded condition, i.e., the condition that the valve has when implanted in the patient. The depiction of valve  10  that is provided in  FIG. 1  may omit certain components that the valve may have, but to some extent this is done to better reveal the components that are depicted in  FIG. 1 . More information will be provided about these possibly omitted components later in this specification. Also,  FIG. 1  shows by representative arrows  42  and  44  that certain parts of the structure shown in the FIG. may deflect farther out and down (in the case of the parts associated with arrows  42 ) or farther out and up (in the case of the parts associated with arrows  44 ) than happens to be shown in  FIG. 1 . This will also be explained in more detail later in this specification. 
     Among the components of valve  10  are an annular metal structure  20 / 30 / 40 , and a leaflet structure  100 . Metal structure  20 / 30 / 40  forms a complete, continuous annulus around a longitudinal axis (not shown) that passes through the center of the valve. This central longitudinal axis is vertical, given the orientation of the valve shown in  FIG. 1 . Structure  20 / 30 / 40  can be reduced in annular size from the size shown in  FIG. 1  by compressing that structure in the annular or circumferential direction. When this is done, structure  20 / 30 / 40  shrinks by partial collapse of the diamond-shaped cells  22  and  46  of aortic portion  20  and annulus portion  40 . Later FIGS. will show examples of how such cells and/or other collapsible shapes can collapse or shrink in a direction that is annular of the valve. In other words, when the structure is thus made to shrink in the annular direction, the length of the perimeter measured around the outside of the valve becomes smaller. There is no significant change in the overall topological shape of the valve, especially metal structure  20 / 30 / 40 , between its large and small perimeter sizes or at any time as it transitions between those sizes. For example, if the valve is approximately a circular annulus in its full ( FIG. 1 ) size, it remains an approximately circular annulus as it is reduced to its smaller perimeter size. It is preferred that there be no folding, wrapping, overlapping, or other major topological shape change of metal structure  20 / 30 / 40  to reduce its perimeter size or to subsequently re-expand it. 
     The above-described changes (i.e., collapsing and re-expanding) of metal structure  20 / 30 / 40  are preferably all elastic deformations. For example, metal structure  20 / 30 / 40  can be resiliently biased to have the size and shape shown in  FIG. 1 . In such a case, collapsing of metal structure  20 / 30 / 40  to the above-mentioned smaller perimeter, annular, or circumferential size can be by elastic deformation of the metal structure, e.g., by confining metal structure  20 / 30 / 40  in a tube having a smaller perimeter than the full  FIG. 1  size of the valve. Such a tube can be part of apparatus for delivering the valve into a patient. When the valve is pushed or pulled out of the tube, metal structure  20 / 30 / 40  automatically, elastically, re-expands to the full size shown in  FIG. 1 . Because such a delivery tube can be smaller than the full size of the valve, the valve can be delivered into the patient less invasively than would be possible if the valve was only capable of always remaining full size as shown in  FIG. 1 . 
     As an alternative or addition to full elastic compression and self-re-expansion, re-expansion may be at least partly assisted by other means. For example, an inflatable balloon on a catheter may be used to assist valve  10  to re-expand to its full size. Such a balloon may be temporarily positioned inside valve  10  to accomplish this. This may be done either because the elastic re-expansion is not quite strong enough to get the valve back to full size when adjacent to surrounding native tissue of the patient, because some plastic re-expansion is required to get the valve back to full size, to help ensure that the valve does in fact firmly seat in and engage the desired surrounding native tissue at the implant site, or for any other reason. For the most part it will be assumed herein that all or substantially all compression and re-expansion are elastic, but the possibility of some plastic compression and re-expansion is also contemplated as mentioned earlier in this paragraph. 
     We turn now to a description of the various parts of metal structure  20 / 30 / 40 . Part  20  is intended for implantation in the patient&#39;s native aorta downstream from the native aortic valve location, and also downstream from the patient&#39;s native valsalva sinus. Part  20  may therefore be referred to as the aortic portion of the valve or of metal support structure  20 / 30 / 40 . Portion  20  is a completely annular (continuous) structure, with the ability to annularly collapse and re-expand as described earlier in this specification. Portion  20  is made up principally of an annular array of parallelogram- or diamond-shaped cells  22 , which give portion  20  the ability to annularly compress and re-expand as described. 
     Part  40  is intended for implantation in the patient&#39;s native aortic valve annulus. Part  40  may therefore be referred to as the annulus portion of the valve or of metal support structure  20 / 30 / 40 . Part  40  is also a completely annular (continuous) structure, with the ability to annularly collapse and re-expand as described earlier in this specification. Part  40  is again made up primarily of an annular array of parallelogram- or diamond-shaped cells  46 , which give portion  40  the ability to annularly compress and re-expand as described. 
     Part  40  also includes three commissure post members  50  that are spaced from one another (e.g., approximately equally) around the valve. Each commissure post member  50  is intended for implantation at the approximate angular or circumferential location of a respective one of the patient&#39;s native aortic valve commissures. Like the native commissures, posts  50  are structures at which adjacent ones of the three leaflets of structure  100  came together in pairs. The blood inflow edge portions (lower as viewed in  FIG. 1 ) of each leaflet are also secured to other structure of the valve below posts  50 . The blood outflow edge portions of leaflets  100  (upper as viewed in  FIG. 1 ) are free (except for their end attachments to a respective pair of posts  50 ). These free edges can come together to close the valve when blood pressure downstream from the valve is greater than blood pressure upstream from the valve. When the blood pressure differential reverses, the greater upstream blood pressure pushes the free edges of the leaflets apart, thereby opening the valve to allow blood flow through it. 
     Leaflet structure  100  is typically made of three flexible leaflet sheets. The material of these sheets can be any known flexible leaflet material such as appropriately treated natural tissue, a flexible polymer, or the like. 
     Each of commissure posts  50  is preferably at least partly cantilevered up (in the blood flow direction) from remaining structure of part  40 . For example, toward its blood inflow (lower) end, each of posts  50  may be attached to other structure of part  40  only near and/or below the middle of that part in the longitudinal (vertical) direction. At least the upper (blood outflow) end portion of each post  50  is therefore cantilevered from that post&#39;s lower-end-portion connections to other structure of part  40 . The upper end portion of each post  50  is accordingly preferably a free end (i.e., without any metal connection to other adjacent metal structure of part  40 ). This has a number of advantages. One of these advantages is that it makes at least the upper portions of posts  50  at least somewhat independent of the other metal structure  20 / 30 / 40  of the device. This makes it possible for at least the upper portions of posts  50  to have properties like flexure characteristics, deflection characteristics, final location characteristics, etc., that can be optimized for the purposes that these post portions must serve, while other portions of metal structure  20 / 30 / 40  can be relatively independently optimized in these various respects for the various purposes that these other portions of structure  20 / 30 / 40  must serve. As an example of this, it may be desirable for the upper portions of posts  50  to stand relatively straight up and to have flexibility that is optimized for absorbing stress from the lateral edges of the leaflets  100  that are attached to those posts. At the same time, it may be desirable for other portions of metal structure  20 / 30 / 40  that are at the same general level along the longitudinal axis of the valve to flare radially out to various degrees. This will be described in more detail later in this specification. But just to complete the point that has been started here, it may be desired for the upper portions of cells  46  to be strong enough to hold back native leaflets and/or native leaflet remnants, and/or to deflect down onto the blood outflow surface of the native valve annulus (especially in cases in which the native leaflets have been wholly or largely removed). Similarly, it may be desirable for the members of strut structures  30  to begin to incline radially outwardly as they extend toward circumferentially larger aortic portion  20  and/or as they pass through the patient&#39;s native valsalva sinus, which is also circumferentially larger than the native valve annulus. 
     Clarification of a point of terminology may be appropriate here. When this specification speaks of a structure extending radially outwardly or the like, this does not necessarily mean that this structure is exactly perpendicular to a longitudinal axis extending in the blood flow direction through the valve. It may only mean that the structure has at least some component of alignment that is radial of the valve, i.e., that the structure (or a geometric projection of the structure) forms some angle with the above-mentioned longitudinal axis. In short, as a general matter, a “radially extending structure” or the like does not have to be fully or exactly radial of the above-mentioned longitudinal axis, but may instead have only some vector component that is radial of that axis. 
     The aortic portion  20  and the annulus portion  40  of metal structure  20 / 30 / 40  are connected to one another by what may be termed struts or strut structures  30 . In the illustrative embodiment shown in  FIG. 1  there are six of these struts  30 . They are in three pairs, with each pair being adjacent to a respective one of the three commissure posts  50 . More particularly, the two struts  30  in each pair are preferably located adjacent (and relatively close to) respective opposite sides of the associated post  50 . This arrangement leaves relatively large open areas (in the circumferential direction) between the pairs of struts  30 . In other words, the distance in the circumferential direction between the struts  30  in any pair of those struts is preferably less than the circumferential distance between the two circumferentially closest struts in any two different pairs of those struts. Because commissure posts  50  are angularly or rotationally aligned with the patient&#39;s native aortic valve commissures, and because struts  30  pass through the patient&#39;s native valsalva sinus relatively close to longitudinal projections of posts  50 , struts  30  are thus located to pass through the valsalva sinus (typically close to or at the wall of the valsalva sinus) along paths that are circumferentially spaced from the ostia of the patient&#39;s coronary arteries. In other words, struts  30  are preferably located in the circumferential direction to pass through the valsalva sinus without any possibility of a strut obstructing the ostium of a coronary artery. (Although patient anatomy can vary in this respect, the coronary artery ostia are typically located in the valsalva sinus between the native aortic valve commissures (or between longitudinal projections of the native aortic valve commissures). See also the later discussion of  FIG. 28 , which discussion applies to embodiments of the kind generally illustrated by  FIG. 1 . In particular, in the terms later discussed in connection with  FIG. 28 , all material of structure  30  at the level of the coronary artery ostia should be confined to areas W as shown in  FIG. 28 .) 
     In addition to the characteristics that are mentioned above, each of struts  30  is preferably serpentine in the longitudinal direction (i.e., as one proceeds along the length of any strut  30  from annulus portion  40  to aortic portion  20 , the strut deviates from a straight line, first to one side of the straight line, then to the other side of the straight line, then back to the first side, and so on). One of the benefits of this type of strut configuration is that it can increase the lateral flexibility of structure  20 / 30 / 40 , especially the lateral flexibility of strut portion  30  between portions  20  and  40 . Lateral flexibility means flexibility transverse to a longitudinal axis that is parallel to blood flow through the valve. Prior to and during implantation, this lateral flexibility can help the valve more easily follow curves in instrumentation that is used to deliver the valve into the patient. After implantation, this lateral flexibility can help each of portions  20  and  40  seat more concentrically in its respective portion of the patient&#39;s anatomy, which portions may not be exactly perpendicularly concentric with one single, common, central longitudinal axis. 
     As shown in  FIG. 1 , the upper end of each strut  30  may connect to the lower end (or apex) of one of the cells  22  of aortic portion  20 . The lower end of each strut  30  may similarly connect to the upper end (or apex) of one of the cells  46  of annulus portion  40 . It should be noted, however, that especially at the lower end of strut structure  30  there are other cells  46  of annulus portion  40  that have no struts  30  connected to their upper ends or apexes. For example, arrows  42  are shown adjacent to the upper ends of two representative ones of cells  46  of this kind. These are the cells  46  whose upper portions can be configured to deflect or project radially outwardly (as indicated by the arrows  42 ) for such purposes (mentioned earlier, and also in more detail later) as holding back any remaining native leaflet material and/or clamping down on the blood outflow side of the patient&#39;s native valve annulus. 
     From the foregoing, it will be seen that the features of valve  10  for holding the valve in place in the patient can include any or all of the following: (1) the radially outward projection of some or all of the lower portions of annulus cells  46  adjacent the blood inflow side of the native aortic valve annulus; (2) the radially outward projection of the upper portions of at least some of the upper portions of annulus cells  46  adjacent possibly remaining native aortic leaflet tissue and/or adjacent the blood outflow side of the native aortic valve annulus; (3) the general radial outward expansion of annulus portion  40  against the native valve annulus; (4) the radial outward expansion of aortic portion  20  to annularly engage the inner wall surface of the aorta downstream from the valsalva sinus; and (5) the possible engagement of the inner wall surface of the valsalva sinus by strut structures  30  passing through that sinus. Although not shown in  FIG. 1 , it is possible to add to any suitable portion(s) of metal structure  20 / 30 / 40  barbs that project out from other adjacent structure so that they additionally engage, dig into, and/or penetrate tissue to give the implanted valve additional means for maintaining its position in the patient. 
     Note also that in addition to possibly engaging possibly remaining native aortic valve leaflet tissue, valve  10  has many structures for pushing any such remaining tissue radially outwardly away from possible interference with prosthetic leaflet structure  100 . These structures include the upper portions of all of cells  46  and the lower portions of all of struts  30 . 
     There are some other possible features of valve  10  that have not yet been mentioned. One of these aspects is the provision of apertures like  52  through commissure posts  50  (and possibly other portions of metal structure  20 / 30 / 40 ) for facilitating the attachment (e.g., using suture material or other similar strand material) of leaflet structure  100  to the metal structure. Other layers of material such as tissue, fabric, or the like may also be attached to various parts of metal structure  20 / 30 / 40  for various purposes. These purposes may include (1) helping to prevent, reduce, or cushion contact between leaflet structure  100  and metal structure  20 / 30 / 40 ; (2) helping to improve sealing between the valve and the surrounding native tissue (e.g., to prevent paravalvular leakage); and (3) helping to promote tissue in-growth into the implanted valve. Limited examples of such additional layers of material are shown in  FIG. 1  in the form of lower fabric skirt  110  and blood inflow edge sealing ring  120 . Both of structures  110  and  120  extend annularly around the outside of the lower (blood inflow) edge of valve  10 . Structures like  110  and  120  may be held to metal structure  20 / 30 / 40  by sutures or other similar strand-like material, and apertures (like  52 ) through the metal structure (or other features of the metal structure) may be used to provide anchoring sites for such sutures or the like. Still other possible aspects of valve  10  will be discussed in connection with later FIGS. 
     A possibly important feature of valves in accordance with the present invention is that they can include a structure near the blood inflow edge for clamping adjacent native tissues in a particular way. In particular, the upper and lower portions of at least some of cells  46  can both pivot toward one another from a common central location. This is illustrated schematically in  FIGS. 2 and 3 . 
       FIG. 2  shows the somewhat simpler case in which the patient&#39;s native aortic valve leaflets have been removed prior to implanting valve  10 . The native tissue structures that are visible in  FIG. 2  are a portion  220  of the wall of the left ventricle, a portion  210  of the aortic valve annulus, and a portion  230  of the wall of the valsalva sinus. The upper portion of a representative cell  46  from  FIG. 1  is shown schematically in  FIG. 2  by member  142 . The lower portion of that cell is shown schematically by member  144 . Members  142  and  144  can pivot toward one another about central pivot point  143 . As in  FIG. 1 , this is again indicated by arcing arrows  42  and  44 . Thus members  142  and  144  initially form a relative large, open jaw structure, the two jaws of which can be released to resiliently pivot toward one another to clamp down on any tissue within their reach. In the case of  FIG. 2 , this can include some of the tissue of sinus wall  230  and the upper surface of annulus  210  (for upper pivoting member  142 ), and some of the tissue of left ventricle wall  220  and the lower surface of annulus  210  (for lower pivoting jaw member  144 ). Clamping force vector component diagrams in  FIG. 2  indicate the nature of the clamping forces that can result from these kinds of tissue engagement. For example, member  142  can have a radially outward clamping force component  142   a  and a longitudinally downward clamping force component  142   b . Similarly, member  144  can have a radially outward clamping force component  144   a  and a longitudinally upward clamping force component  144   b . Opposing clamping force components  142   b  and  144   b  tend to clamp tissue between members  142  and  144 . But radially outward force components  142   a  and  144   a  also engage tissue and therefore also help to hold valve  10  in place in the patient. 
       FIG. 3  illustrates the somewhat more elaborate case in which native aortic leaflet tissue  240  (typically, or at least often, stenotic) remains in the vicinity of prosthetic valve  10  when the valve is implanted.  FIG. 3  shows that in this type of situation upper member  142  both engages leaflet tissue  240  and helps to push it radially out of the way. Again, member  142  exerts both a radially outward force component  142   a  and a longitudinal (downward) force component  142   b  on the adjacent tissue (in this case leaflet tissue  240 ). The behavior and effects of lower member  144  are similar to what is shown in  FIG. 2  and described earlier. Thus again the structures of valve  10  exert both radial outward tissue engaging forces  142   a / 144   a  and oppositely directed tissue clamping forces  142   b / 144   b  to hold valve  10  in place in the patient. 
     Recapitulating and extending the above, the attachment method of the present design applies forces in the radial and longitudinal directions to clamp onto several anatomical features, not just annulus  210 . In doing this, a valve in accordance with this invention can maximize (or at least significantly increase) the orifice area at the annulus level for better blood flow. Another way of thinking about the present designs is not necessarily as “clamps,” but rather as members of a stent that conforms to the different diameters of different portions of the anatomy. Structures that only “clamp” tend to engage only both sides of the native annulus (like  210 ), and do not also extend to and engage other tissue structures as in the present designs. The present structures also differ from “clamp” structures that terminate from a single pointed wire. Instead, in the present designs, the conforming members are formed from continuous strut members of the base (annulus portion  40 ) of the stent. This can only be achieved with an annulus portion  40  that stays below the ostia of the coronary arteries and with commissure posts  50  that are “independent” of other structure of annulus portion  40  as was described earlier in this specification. 
     Still other features of the present valves that warrant emphasis are mentioned in the following. The annulus portion  40  of the present valves preferably expands as nearly as possible to the full size of the native valve annulus. The leaflet structure  100  is preferably mounted just inside annulus portion  40 . This helps the present valves avoid any stenotic character (such as would result from having the leaflet structure or some other structure on which the leaflet structure is mounted) spaced radially inwardly from annulus portion  40 . The present valves are thus ensured to have the largest opening for blood to flow through, which reduces the pressure gradient (drop) across the valve. 
     Note that at the level of the coronary artery ostia, the present valves have only very minimal non-leaflet structure  30 ; and even that minimal non-leaflet structure is rotationally positioned to pass through the valsalva sinus where it will safely bypass the coronary artery ostia. Annulus portion  40  is preferably designed to be entirely upstream (in the blood flow direction) from the coronary artery ostia. Aortic portion  20 , on the other hand, is preferably designed to be entirely downstream from the coronary artery ostia (i.e., in the aorta downstream from the valsalva sinus). Some prior designs have much more extensive non-leaflet structures extending much farther into or through the valsalva sinus and therefore longitudinally beyond the coronary artery ostia. This is believed to be less desirable than the present structures. 
     The present valves preferably include “independent” commissure posts  50  that are “lined up” or aligned with (i.e., superimposed over) the native valve commissures. This also helps to ensure proper coronary artery flow, when combined with the fact that struts  30  are confined to being closely adjacent to posts  50  in the circumferential direction. Even relatively thin connecting members (like struts  30 ) could partially block a coronary artery if not correctly positioned in the circumferential direction around the valsalva sinus. But this is avoided in the present valves by the principles and features mentioned, for example, in the immediately preceding sentences. 
       FIG. 4  shows another illustrative embodiment of metal support structure  20 / 30 / 40 .  FIG. 4  shows this structure as though cut along its length and then laid flat.  FIG. 4  also shows this structure in the condition that it has in its circumferentially collapsed condition. Thus, for example, the sides of what will be diamond-shaped cells  22  and  46  in the re-expanded valve are, in  FIG. 4 , collapsed down to being parallel with one another. Again, the fact that FIGS. like  FIG. 4  show structures as though cut longitudinally and laid flat is only for ease and convenience of depiction. In actual fact these structures are complete and continuous annular structures like the structure  20 / 30 / 40  shown in  FIG. 1 . 
     Note that in the  FIG. 4  design there are eyelets  24  in aortic section  20  for attachment of material and/or attachment of wires/sutures for a delivery system. On annulus section  40  the eyelets  48 / 52  can be used for attachment of the cuff, porcine buffer, and/or leaflets.  FIG. 4  shows an annulus portion  40  with a “scalloped” inflow (lower) edge. This scalloped blood inflow edge is relatively “high” in the vicinity of the inflow end of each commissure post  50 , and relatively “low” between commissure post  50  inflow ends. (“High” means more downstream; “low” means more upstream.) This can help the implanted valve avoid affecting the patient&#39;s mitral valve, which tends to be radially spaced from the aortic valve along a radius of the aortic valve that corresponds to the radial location of one of the aortic valve&#39;s commissures. Because the valves of this invention are preferably implanted with posts  50  superimposed inside the native valve commissures, this places one of the “high” portions  41  of the inflow edge adjacent the patient&#39;s mitral valve. The resulting recessing  41  of annulus portion  40  helps the prosthetic valve avoid interfering with the mitral valve. 
       FIG. 5  shows yet another illustrative embodiment of metal support structure  20 / 30 / 40 .  FIG. 5  shows this embodiment in the same general way and condition as  FIG. 4  shows its embodiment. Thus, as said in connection with  FIG. 4 , the structure shown in  FIG. 5  is actually a complete, continuous annulus, and the longitudinally cut and flattened depiction shown in  FIG. 5  is only employed for simplicity and greater clarity. 
     The  FIG. 5  embodiment again has eyelets  24  in the aortic section  20  for attachment of material and/or attachment of wires/sutures for a delivery system. Also, eyelets  48 / 52  on annulus section  40  can be used for attachment of the cuff, porcine buffer, and/or leaflets. As compared to the  FIG. 4  design (in which connecting support struts  30  are connected to the downstream apexes of certain annulus portion cells  46 ), in  FIG. 5  the connecting support struts  30  are connected directly to posts  50 . The aortic portion  20  of the  FIG. 5  embodiment also has two annular arrays of cells  22   a  and  22   b  (rather than only one annular array of such cells  22  as in the earlier embodiments). Array  22   a  is more downstream than array  22   b , but these two arrays do overlap somewhat in the longitudinal direction by virtue of the cells in the two arrays having some intervening cell members (like representative member  23 ) in common. 
     A typical way of making any of the support structures  20 / 30 / 40  of this invention is to laser-cut them from a tube. 
       FIG. 6  shows another illustrative embodiment of aortic portion  20 , in which the cells  22  of the mesh stent can expand against the ascending aorta. This structure may or may not be covered in tissue, polymer, and/or fabric (true for any of the embodiments shown and described herein). 
       FIGS. 7 and 8  show another illustrative embodiment of annulus portion  40 . This mesh stent has expandable cells that press against the native valve annulus and/or leaflets (if the native leaflets remain). Upper  142  and lower 144 portions of this stent clamp down on the native annulus and/or leaflets. This stent design is symmetrical around the circumference, but it may be asymmetrical to allow anatomical conformance with the mitral valve, for example. A cuff  110  made of fabric, tissue, or polymer may fully or partially encapsulate this stent as shown, for example in  FIG. 8 . 
       FIGS. 9 and 10  show an embodiment of stent  40  that includes a set of barbs  43  on the top and/or bottom to further secure the stent in order to stop migration. A partial cuff  110  ( FIG. 10 ) allows the barbed tips  43  to be exposed to direct tissue contact for enhanced securing. The bottom section could be asymmetrical (e.g., as in  FIGS. 4 and 5 ) to mitigate any impingement on the mitral valve. An extra-thick, toroidal section  112  of the cuff allows extra sealing capacity to prevent paravalvular leakage. 
       FIG. 11  shows that toroidal section  112  of cuff  110  allows extra sealing capacity to prevent paravalvular leakage. This section could be made of extra fabric, tissue, or polymer. The chamber  114  inside section  112  can accommodate an injectable polymeric substance to aid in seating. 
       FIG. 12  shows another illustrative embodiment of the aortic holding portion  20 . In this case portion  20  is a metallic or polymeric expandable wire form with many of the same attributes discussed with the mesh stent. 
       FIG. 13  shows another illustrative embodiment of annulus/leaflet holding portion  40 . In this case portion  40  is a metallic or polymeric expandable wire form with many of the same attributes discussed with the mesh stent. 
       FIGS. 14 and 15  show an illustrative assembly of an aortic portion  20  and an annulus portion  40 . In  FIG. 15  a pliable or semi-rigid reinforced fabric  30  connects the aortic portion  20  and the annulus/cuff portion  40 / 110 / 112  to allow somewhat independent movement. The tissue or synthetic leaflets  100  can then be attached to connecting section  30 . All of the disclosed variations allow for ample areas (like  130 ) for blood to flow to the coronaries. 
     The variation shown in  FIG. 16  does not include an aortic portion  20 . Instead, three independent commissure posts  50  allow for leaflet attachment (e.g., with the aid of apertures  52 ), while the base  40  is secured in place as described earlier. Posts  50  can be lined up with the native commissures and (by virtue of the recesses like the one identified by reference number  41 ) allow for an opening on the lower portion to be clear of chordae and the mitral valve. The posts  50  used to attach the leaflets may be solid or have any combination of holes, slots, and/or other apertures  52 . 
     Note that even for an embodiment like  FIG. 16 , when used for an aortic valve, any non-leaflet portion of the valve (such as commissure posts  50 ) that extends into the coronary sinus to the level of any coronary artery ostium is confined, in the circumferential direction, to locations that are well spaced from the coronary artery ostia. This is preferably accomplished by having all such non-leaflet structure confined (in the circumferential direction) to locations or areas that are at or circumferentially near the native aortic valve commissures (or downstream projections of those commissures). The circumferential width of each of these areas in which non-leaflet structure is permitted at the level of the coronary artery ostia is preferably less than the circumferential spacing at that level between circumferentially adjacent ones of those areas. It is not a problem for moving leaflet material to extend to or even beyond the level of the coronary artery ostia because the coronary arteries can fill with blood when the valve is closed. But no non-leaflet and therefore basically non-moving part of the prosthetic valve should be allowed to occupy any location at the level of the coronary artery ostia where that non-leaflet material may interfere with blood flow into the coronary arteries. 
       FIG. 28  illustrates the point made in the immediately preceding paragraph (and also elsewhere in this specification).  FIG. 28  shows a cross section of a typical patient&#39;s valsalva sinus  300  at the level of the coronary artery ostia. The patient&#39;s native aortic commissures (or downstream projections of those commissures) are at locations  310   a - c . The coronary artery ostia typically occur in bracketed areas  320 . Any non-leaflet structure of a prosthetic valve in accordance with this invention that is at the level depicted by  FIG. 28  should be confined to areas W. The width of each of these areas in the circumferential direction (i.e., the dimension W) is preferably less than the distance S in the circumferential direction between any two circumferentially adjacent ones of these areas. 
       FIG. 17  shows another illustrative embodiment that is somewhat like the embodiments in  FIGS. 1, 4, and 5  in that there is a continuous link  30  between aortic section  20  and annulus section  40 . In this embodiment link structure  30  itself allows for leaflet attachment, with the lower portion of each link  30  acting like a commissure post  50 . To mitigate leaflet abrasion at the attachment site in this or any other embodiment, the stent may first be covered with fabric, followed by a thin layer of buffering tissue/polymer, and finally the leaflet tissue/polymer. The stent of the valve can be partially or completely covered in one or a combination of materials (polyester, tissue, etc.) to allow for better in-growth, abrasion protection, sealing, and protection from metal leachables like nickel from nitinol. 
     Most of the detailed discussion thus far in this specification has related to prosthetic aortic valves. However, certain aspects of what has already been said can also be applied to making prosthetic valves for other locations in the heart. The mitral valve is another valve that frequently needs replacement, and so this discussion will now turn to possible constructions for other valves such as the mitral valve. 
     In the case of the mitral valve (which supplies blood from the left atrium to the left ventricle), only the native valve annulus area (possibly including what is left of the native valve leaflets) is available for anchoring the prosthetic valve in place. There is nothing comparable to the aorta for additional downstream anchoring of a prosthetic mitral valve. 
     Structures of the types shown in  FIGS. 7-11 and 13  are suitable for use in prosthetic mitral valves. In such use, annular structure  40  may be delivered into the native mitral valve annulus in a circumferentially collapsed condition and then re-expanded to the depicted size and condition in that annulus. The apex portions  142  of cells  46  at one end of structure  40  (e.g., the blood inflow end) project resiliently out and also pivot somewhat downstream as shown, for example, in  FIG. 7  and engage the patient&#39;s tissue adjacent the inflow side of the patient&#39;s native mitral valve annulus. Apex portions  144  of cells  46  at the other end of structure  40  (e.g., the blood outflow end) project resiliently out and also pivot somewhat upstream and engage the patient&#39;s tissue adjacent the outflow side of the patient&#39;s native valve annulus. The tissue of and adjacent to the mitral valve annulus is thereby clamped between tissue clamping structures  142  and  144 . Barbs  43  may be added as shown in  FIGS. 9 and 10  for additional tissue engagement and possible penetration to additionally help hold the valve in place in the mitral valve annulus. Other features (e.g.,  110  and  120 ) and principles discussed earlier in connection with  FIGS. 7-11 and 13  apply to the possible mitral valve use of these structures and features. 
     An illustrative embodiment of a more fully developed prosthetic mitral valve  210  in accordance with the invention is shown in  FIG. 18 . In this depiction of mitral valve  210 , its blood inflow end is down, and its blood outflow end is up. (This depiction may be regarded as “upside down” as compared to its orientation in a patient who is standing upright.) Analogous to what is shown in  FIG. 16 , valve  210  has three commissure posts  50  that are cantilevered from annular structure  40 . Flexible valve leaflets  100  are attached to these posts (and elsewhere to other structure of the valve such as annular structure  40  and/or material that is used to cover structure  40 ). Apertures  52  through posts  50  may be used to facilitate attachment (e.g., suturing) of the leaflets to the posts. Additional apertures  54  in posts  50  may be used as sites for or to facilitate attachment of chordae tendonae (native and/or artificial replacements) to the posts. This last point will be considered further as the discussion proceeds. 
     The posts  50  used to attach the leaflets can be solid or can have any combination of holes and/or slots. Three independent posts  50  (i.e., “independent” because cantilevered from annular structure  40 ) allow for leaflet attachment, while the base  40  is secured in place as described earlier. Also, posts  50  can be lined up with the native anatomy for better leaflet opening clear of chordae and the aortic valve. Apertures  54  can be included near the downstream free ends of posts  50  for native and/or artificial chordae attachment. To mitigate leaflet abrasion at the attachment site, the stent  40  can first be covered with fabric, followed by a thin layer of buffering tissue/polymer, and finally the leaflet  100  tissue/polymer. As is true for all embodiments herein, the stent  40  of the valve can be partially or completely covered in one or a combination of materials (polyester, tissue, etc.) to allow for better in-growth, abrasion protection, sealing, and protection from metal leachables such as nickel from nitinol. The support structure  50  for the leaflets may be continuous from the clamping stent portion  40 . Alternatively, the leaflet support structure may be a separate section connected to clamping portion  40 , or it may be frameless. 
       FIG. 19  shows an example of how artificial and/or native chordae  220  can be attached prior to, during, or after implanting prosthetic mitral valve  210 . These chordae attachments are made at or near the downstream free ends of posts  50 . Chordae  220  can be adjusted through cored papillary muscles and/or through a port made in the apex of the beating heart. 
       FIG. 20  shows an alternative embodiment of prosthetic mitral valve  210  in which chordae  230  can be attached to an extended free edge  102  of the leaflets prior to, during, or after implanting of the valve in the patient. Once again, chordae  230  can be adjusted through cored papillary muscles and/or through a port made in the apex of the beating heart. The redundant coaptation portions  102  of the leaflets can be reinforced tissue (e.g., a double layer or thicker tissue), or if the leaflet is a polymer, it can be reinforced by greater thickness and/or fibers. 
       FIG. 21  shows that the stent  40  design can include apertures  48  around the center portion of the stent to allow for cuff, leaflet, and chordae attachment around the circumference of the stent.  FIG. 22  shows that the edge of cuff  110  can follow the edge shape of stent  40  to allow for passage of chordae and reduction of interference of other anatomy, while also allowing greater flexibility of annular structure  40 .  FIG. 23  shows chordae  240  extending from apertures like those shown at  48  in  FIG. 21 . 
       FIG. 24  illustrates the point that variations in stent cell  46  geometry around the circumference of annular structure  40  can reduce impingement on or of the aortic valve, chordae, and the coronary sinus. Additionally, extended portions (e.g.,  244 ) of some cells may allow for greater holding force in certain parts of the anatomy such as in the atrial appendage. 
       FIGS. 25 and 26  show other variations in the shape of annular structure  40  that can allow for better conformance to the mitral valve anatomy. For example,  FIG. 25  shows an asymmetric shape, while  FIG. 26  shows a symmetric saddle shape. 
       FIG. 27  shows that a valve  210  with an elliptical shape may also conform better to the mitral valve anatomy than a circular-shaped valve. Additionally, instead of a tri-leaflet design,  FIG. 27  shows that a bi-leaflet design  100 ′ can be used (leaflets shown open in  FIG. 27 ). Once again, chordae  220  can be attached at commissure posts  50 , and the edge of cuff  110  can be contoured to follow the edge of stent  40 . 
     Although the structures shown in  FIGS. 18-27  are described primarily as mitral valve structures, it will be understood that this is only illustrative, and that various structures and principles illustrated by or in these FIGS. can be employed in other types of prosthetic heart valves (e.g., in prosthetic aortic valves). 
     Briefly recapitulating some of what has been said in somewhat different terms, it will be seen that in many embodiments of the invention, at least the portion  40  of the prosthetic valve that goes in the patient&#39;s native valve annulus includes an annular array of generally diamond-shaped cells  46 . Upstream apex portions  144  of at least some of these cells are resiliently biased to deflect radially outwardly from at least some other portions of structure  40 . Downstream apex portions  142  of at least some of these cells are similarly resiliently biased to deflect radially outwardly from at least some other portions of structure  40 . This allows the valve to clamp tissue of the patient between the upstream and downstream apex portions that thus deflect outwardly. 
     Each of the above-mentioned apex portions comprises two spaced-apart members that join at an apex of that apex portion. For example, in  FIG. 7  the two spaced-apart members of one representative downstream apex portion are identified by reference letters b and c, and the apex where those members join is identified by reference letter a. 
     Still more particularly, the resiliently biased, radially outward deflection of each upstream apex portion  144  typically includes a downstream component of motion of that upstream apex portion (in addition to a radially outward component of motion). This is illustrated, for example, by the arcuate arrows  44  in  FIGS. 1-3 . Similarly, the resiliently biased, radially outward deflection of each of downstream apex portion  142  typically includes an upstream component of motion of that downstream apex portion (in addition to a radially outward component of motion). This is illustrated, for example, by the arcuate arrows  42  in  FIGS. 1-3 . The result of this is that the upstream and downstream apex portions begin as jaws that are relatively far apart and wide open. They then effectively pivot toward one another to clamp tissue therebetween. 
     References herein to an annular perimeter of a structure being changeable in length mean that the perimeter increases or decreases in size without going through any major topological change. In other words, the shape of the structure remains basically the same, and only the perimeter size changes. For example, the shape may be always basically circular. There is no folding or wrapping of the structure to change its perimeter size. The shape either basically shrinks down or expands out. A minor exception to the foregoing is that ellipses and circles are regarded herein as having the same basic topology. Thus an ellipse may shrink to a circle, for example, without that constituting “a major topological change.” 
     It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the particular patterns of stent cells like  22  and  46  shown herein are only illustrative, and many other stent configurations can be used instead if desired. It will be appreciated that the valves of this invention can, if desired, be implanted in a patient less invasively. For example, the valves of this invention can be implanted percutaneously, trans-apically, or surgically, and with or without resected and/or debrided leaflets. Depending on the embodiment, the valve can be collapsed in a variety of configurations before deployment in a single- or multi-stage process. Access can be achieved, for example, through the femoral artery, abdominal aorta, or the apex of the heart.