Patent Description:
The heart is a hollow muscular organ having four pumping chambers separated by four heart valves: aortic, mitral (or bicuspid), tricuspid, and pulmonary. Each heart valve is 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 fabric (e.g., DACRON® polyethylene terephthalate) coverings, and a fabric-covered sewing ring is provided on the inflow end of the peripheral support structure.

Sometimes the need for complete valve replacement may arise after a patient has already had an earlier valve replacement for the same valve. For example, a prosthetic heart valve that was successfully implanted to replace a native valve may itself suffer damage and/or wear and tear many years after initially being implanted. Implanting a new prosthetic heart valve directly within a previously-implanted prosthetic heart valve (a so-called valve-in-valve procedure) may be impractical since traditional prosthetic heart valves may not be configured to easily receive such a valve-within-a-valve implantation in a manner which provides secure seating for the new valve while also having a large enough annulus within the new valve to support proper blood flow therethrough.

Some attention has been paid to the problem of implanting a new valve within an old valve. In particular, the following disclose various solutions for valve-in-valve systems: <CIT>; <CIT>; and International Patent Application Publication No. <CIT>. Typically, the originally implanted heart valve is subjected to an outward dilatory force such as with an expanding balloon, until it expands to permit introduction of a new expandable valve within its orifice. The outward dilatory force from within the heart valve is typically substantially larger than forces associated with normal physiological cycling. The expansion may be done simultaneously with the new valve implantation. Reference is further made to <CIT>, <CIT>, and<CIT>.

Despite certain advances in valve-in-valve technology, there remains a need for a prosthetic heart valve that facilitates valve-in-valve procedures and simplifies manufacturing techniques.

The present application provides a prosthetic heart valve configured to receive an expandable prosthetic heart valve, such as a catheter-deployed (transcatheter) prosthetic heart valve, therein. The prosthetic heart valve replaces a native heart valve and has a support frame configured to be reshaped into an expanded form in order to receive and/or support the expandable prosthetic heart valve therein. A dual-wireform support frame including an upper and a lower wireform permits expansion of the valve by one or two valve sizes, for example, with a <NUM>-mm gap between each valve size. The expansion occurs upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling. The lower wireform has a relatively shallow undulation so that it may stretch apart by a small amount and then prevent further expansion of the valve.

The present invention concerns a prosthetic heart valve adapted for post-implant expansion as disclosed in claim <NUM>. Embodiments of the invention are recited in the dependent claims. The prosthetic heart valve has an inflow end and an outflow end. An upper wireform undulates around a central axis with three upstanding commissure posts extending in an outflow direction alternating with three arcuate inflow cusps, and a fabric covering around the entire upper wireform. A lower wireform undulates around the central axis with three truncated peaks extending in an outflow direction alternating with three arcuate inflow cusp sections, with a fabric covering around the entire lower wireform. The lower wireform is positioned axially below the upper wireform with the three truncated peaks being aligned under three upstanding commissure posts of the upper wireform, and wherein the truncated peaks have an axial height of between about <NUM>-<NUM>% of the commissure posts. Three flexible leaflets having outer arcuate cusp edges attach between the inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform. Outer tabs of the leaflets extend outward between the commissure posts of the upper wireform and the truncated peaks of the lower wireform and are secured to the fabric covering around the upper wireform, the flexible leaflets being configured to ensure one-way blood flow through the heart valve. The inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform together define an implant circumference having a first diameter, wherein the upper and lower wireforms permit expansion of the heart valve from the first diameter to a second diameter no greater than <NUM> larger than the first diameter upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling. Finally, the lower wireform has a shallow undulating shape that flattens out and prevents expansion of the heart valve beyond the second diameter.

The prosthetic heart valve of the first aspect may further include three fabric-covered inserts located above the truncated peaks of the lower wireform that extend upward radially outward of the commissure posts of the upper wireform, the leaflet tabs being also secured to the inserts. Preferably, a lower end of each insert has an inverted Y-shape that closely matches a shape of the truncated peaks of the lower wireform.

The prosthetic heart valve of the first aspect may further include an annular sealing ring disposed outward of the inflow cusp sections of the lower wireform and being secured thereto, the annular sealing ring being suture permeable. In one embodiment, the lower wireform is embedded within the sealing ring.

The lower wireform may comprises a solid wire or a braided cable.

The prosthetic heart valve of the first aspect may further include an expandable frame attached to an inflow end of the heart valve and projecting therefrom in the inflow direction, the expandable frame having an upper undulating strut that extends around an entire periphery thereof and a plurality of lower struts. The undulating strut has a shape that closely follows the shape of the undulating lower wireform, wherein there are no lower struts below three peaks of the undulating strut to permit flattening out of the undulating strut upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling.

In an example, a prosthetic heart valve adapted for post-implant expansion and having an inflow end and an outflow end, comprises an upper wireform undulating around a central axis with three upstanding commissure posts extending in an outflow direction alternating with three arcuate inflow cusps, and a fabric covering around the entire upper wireform. An annular sealing ring is disposed outward of the inflow cusps of the upper wireform and is secured thereto, the annular sealing ring being suture permeable. A braided cable undulates around the central axis with three truncated peaks extending in an outflow direction alternating with three arcuate inflow cusp sections, the braided cable being embedded within the sealing ring and the three truncated peaks being aligned under three upstanding commissure posts. Three flexible leaflets having outer arcuate cusp edges attach between the inflow cusps of the upper wireform and the sealing ring. Outer tabs of the leaflets extend outward between the commissure posts of the upper wireform and are secured to the fabric covering around the upper wireform, the flexible leaflets being configured to ensure one-way blood flow through the heart valve. The inflow cusps of the upper wireform and the inflow cusp sections of the braided cable together define an implant circumference having a first diameter, wherein the upper wireform and braided cable permit expansion of the heart valve from the first diameter to a second diameter no greater than <NUM> larger than the first diameter upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling. Finally, the braided cable has a shallow undulating shape that flattens out and prevents expansion of the heart valve beyond the second diameter.

The prosthetic heart valve of the example may further include three fabric-covered inserts located above the truncated peaks of the braided cable that extend upward radially outward of the commissure posts of the upper wireform, the leaflet tabs being also secured to the inserts. Lower ends of each insert may have an inverted Y-shape that closely matches a shape of the truncated peaks of the braided cable.

The braided cable may be joined together at free ends at a weld in one of the cusp sections, or at a crimp at one of the truncated peaks.

The prosthetic heart valve of the example may further include an expandable frame attached to an inflow end of the heart valve and projecting therefrom in the inflow direction, the expandable frame having an upper undulating strut that extends around an entire periphery thereof and a plurality of lower struts. The undulating strut has a shape that closely follows the shape of the undulating lower wireform, wherein there are no lower struts below three peaks of the undulating strut to permit flattening out of the undulating strut upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling.

Other features and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, certain principles and examples.

The prosthetic heart valves disclosed herein include a prosthetic valve member constructed similarly to embodiments of some commercially available surgical valves, with a relatively stable diameter that is not intended to be compressed or expanded during delivery and after implant when functioning as a one-way valve. The prosthetic heart valves described herein each include an internal (meaning incorporated into the valve member itself as opposed to being a supplemental element) structural stent or frame that is generally tubular in shape and that defines a flow orifice area through which blood flows from an inflow end to an outflow end. Alternatively, the shape of the internal stent can be oval, elliptical, D-shaped, irregular, or any other desired and functional shape. The valves include flexible leaflets that selectively open and close to allow for one-way fluid flow therethrough.

The present application discloses specific modifications to existing surgical valves that enable manufacturers to rapidly produce a valve that accommodates valve-in-valve (ViV) procedures. Specifically, the present application contemplates modifying certain components within existing surgical valve designs to enable post-implant expansion, which not only converts any proven surgical valve design for use in a ViV procedure, but it also reduces design and manufacturing work. Consequently, components of one popular surgical valve are described below to illustrate certain modifications thereto.

<FIG> are various views of an exemplary surgical prosthetic heart valve <NUM> oriented around a flow axis <NUM>. The heart valve <NUM> comprises a plurality (typically three) of flexible leaflets <NUM> supported partly by an undulating upper wireform <NUM> as well as by a lower wireform <NUM>. The upper wireform <NUM> and lower wireform <NUM> are visible in the figures, but are normally separately covered with a polyester fabric to facilitate assembly and reduce direct blood exposure after implant. The directions up and down are aligned along the flow axis <NUM> and generally correspond to flow directions, with the blood flowing up along the axis past the leaflets <NUM> in an outflow direction when the heart valve <NUM> is implanted.

Certain characteristics of the prosthetic heart valve <NUM> are common to a number of different prosthetic heart valves, such as pericardial heart valves manufactured by Edwards Lifesciences of Irvine, CA. For example, the Edwards PERIMOUNT® heart valves that utilize pericardial leaflets <NUM> features a leaflet-supporting wireform such as the upper wireform <NUM>, but also has an inner stent comprising a relatively non-expandable circular band structure. The exemplary heart valve <NUM> disclosed herein improves on the PERIMOUNT® heart valves by avoiding inner support structure which inhibits post-implant expansion.

<FIG> is an elevational view of the upper wireform <NUM>, <FIG> is an elevational view of a lower wireform <NUM>, and <FIG> is a schematic view showing the upper and lower wireforms in the approximate positions they assume when assembled within the heart valve <NUM>. The upper wireform <NUM> may be formed from a suitably elastic metal, such as a Co-Cr-Ni alloy like ELGILOY® alloy. The upper wireform <NUM> has a continuous undulating wire-like structure with (preferably) three upstanding commissure posts <NUM> in between three downwardly curved valleys typically termed cusps <NUM>, as best seen in <FIG>. The wireform <NUM> forms narrow inverted "U" shapes at the commissure posts <NUM> that project in the outflow direction and define the farthest extent of the valve in that direction aside from fabric covering. This undulating band shape is useful for prosthetic aortic heart valves, which typically have three leaflets joined at their adjacent edges at the upstanding commissure posts <NUM>. Of course, the heart valves disclosed herein may be utilized in other implant locations, such as the pulmonary, mitral, or tricuspid annulus.

The lower wireform <NUM> is preferably metallic as well, but may be solid or a braided structure, as will be discussed. As seen in <FIG>, the lower wireform <NUM> has generally the same shape as the upper wireform <NUM> but with three truncated peaks <NUM> intermediate three cusp sections <NUM>. The three cusp sections <NUM> closely parallel the cusps <NUM> of the upper wireform <NUM>, but the truncated peaks <NUM> terminate well below the commissure posts <NUM>.

In the illustrated embodiment, the peaks <NUM> of the lower wireform <NUM> are rotationally aligned with the commissure posts <NUM> of the upper wireform <NUM>. In other embodiments, one or more of the peaks <NUM> is rotationally offset from the commissure posts <NUM>. For example, in some embodiments, at least two peaks <NUM> are rotationally offset in the same direction. In some embodiments, at least a first peak is rotationally offset in an opposite direction as a second peak. In some embodiments, a first peak is rotationally offset by a different angular distance than a second peak.

Moreover, although the illustrated embodiment of the upper wireform <NUM> includes three commissure posts <NUM>, in other embodiments, the upper wireform includes a different number of commissure posts, for example, two or four. In the illustrated embodiment, the number of peaks <NUM> on the lower wireform <NUM> matches the number of commissure posts <NUM> on the upper wireform <NUM>: in this example, three of each. In other embodiments, the number of peaks is different than the number of commissure posts. For example, some embodiments include fewer peaks than commissure posts, for example, two peaks on a device with three commissure posts. Other embodiments include more peaks than commissures, for example, by replacing at least one of the peaks <NUM> with two peaks.

<FIG> is a view of the dual wireform assembly in a relaxed, unexpanded configuration showing exemplary dimensions. In a preferred embodiment, the truncated peaks <NUM> of the lower wireform <NUM> have an axial height H<NUM> of only about <NUM>-<NUM>% of the axial height H<NUM> of commissure posts <NUM> of the upper wireform <NUM>, and more preferably about <NUM>%. The upper and lower wireforms <NUM>, <NUM> define a circle of rotation at their inlet ends having a common diameter D<NUM>, with the two wireforms axially stacked and the lower wireform just below the upper wireform. Typically, heart valves are available in labeled sizes from <NUM> to up to <NUM> in <NUM>-mm increments (e.g., <NUM>, <NUM>, <NUM>. ), and the diameter D<NUM> is between <NUM>-<NUM>, roughly corresponding to the labeled diameter of the finished valve <NUM>. Other sizing schemes are also possible, for example, even millimeter sizing, and/or a sizing scheme implementing at least one different increment between sizes. The valves <NUM> disclosed herein have a functional size which equals the labeled size, whereas the valve becomes non-functional when expanded outward post-implant.

<FIG> is a view of the dual wireform assembly after expansion and showing altered dimensions d<NUM>, h<NUM>, h<NUM>. Namely, the dimension or diameter d<NUM> widens or increases by up to about <NUM>-<NUM>, preferably closer to about <NUM> for smaller valves and about <NUM> for larger valves. Recent publications report a drastically higher probability of annular rupture upon expanding the native annulus by more than <NUM>% by area, such as when expanding a prosthetic heart valve therein. In light of this information, it is desirable to ensure that an expandable surgical valve expands by less than about <NUM>% by area in some embodiments. Thus, for example, for a <NUM>-mm valve a <NUM>% increase in area corresponds to an increase in diameter of about <NUM>.

In other embodiments, the upper and lower wireforms <NUM>, <NUM> do not have a common diameter. For example, in some embodiments, the lower wireform has a larger diameter than the upper wireform. In some of these embodiments, such a configuration permits nesting the upper wireform within the lower wireform, thereby reducing the overall height (H<NUM> and h<NUM>) of the device. In some of these embodiments, the final diameters (d<NUM> in <FIG>) of the upper and lower wireforms is different, while in other embodiments, the final diameters are substantially the same.

The heights h<NUM>, h<NUM> of the upper and lower wireforms <NUM>, <NUM>, respectively, decrease when the wireforms expand. Because of the relatively high commissure posts <NUM> of the upper wireform <NUM>, and their large capacity to expand outward toward the cusps <NUM>, the height h<NUM> decreases a smaller proportion of the original height H<NUM> compared with h<NUM>/H<NUM>. However, since the lower wireform <NUM> has relatively shallower undulations between the peaks <NUM> and cusp sections <NUM> compared with the upper wireform <NUM>, the reduced height h<NUM> is preferably less than about <NUM>% of the original height H<NUM>. More preferably, the lower wireform <NUM> flattens out to a great extent to more closely resemble a flat ring, thus presenting a relatively strong impediment to further expansion, such as with an expanding balloon during a valve-in-valve procedure. The expanded lower wireform <NUM> is shown with slight undulations, although it could be much flatter depending on the original height H<NUM> and the extent of expansion. Preferably the hoop strength of the lower wireform <NUM> increases to a magnitude sufficient to withstand balloon expansion from within after an expansion of between about <NUM>-<NUM> in diameter.

With reference back to <FIG>, further constructional details of the heart valve <NUM> include a plurality of inserts <NUM> which are located generally between the commissure posts <NUM> of the upper wireforms <NUM> and the peaks <NUM> of the lower wireforms <NUM> and help secure the leaflets <NUM> in place. One of the inserts <NUM> is shown covered with cloth in <FIG>. Additionally, a suture permeable sealing ring <NUM> surrounds the inlet end of the valve <NUM> and is used to secure the valve to the annulus. Typically, the sealing ring <NUM> comprises silicone, cloth or other such suture-permeable material, and is covered in fabric as seen in <FIG>.

Outer tabs <NUM> of adjacent leaflets <NUM> wrap around upper ends of commissure inserts <NUM> (preferably three) that project in an outflow direction along the flow axis <NUM>. The commissure inserts <NUM> comprises elements separate from either the upper and lower wireforms <NUM>, <NUM>, and each has an inverted "Y" shape with a forked lower end <NUM> that generally conforms to a peak <NUM> of the lower wireform <NUM>. Once covered in fabric, as illustrated for the one of the inserts shown in <FIG>, the inserts <NUM> are preferably positioned above the fabric-covered lower wireform <NUM> and secured to the leaflets <NUM> and fabric-covered upper wireform <NUM>. Arcuate cusp edges of the leaflets <NUM> preferably extend between the cloth covered wireforms <NUM>, <NUM> and are secured thereto with sutures.

Once assembled with the other valve components, the combination of the upper and lower wireforms <NUM>, <NUM> presents a relatively dimensionally stable circumferential base to the valve <NUM>, which is beneficial for typical surgical use. That is, primarily the lower wireform <NUM> provides good ring support to the cusp edges of the leaflets <NUM> and helps provide resistance to deformation of the valve during implantation. However, because of its undulating shape, the lower wireform <NUM> facilitates limited expansion of the valve <NUM>.

During a valve-in-valve procedure, as the lower wireform <NUM> expands, the commissure posts <NUM> become spaced apart since the upper wireform <NUM> expands outward, which may lead to a loss of function of the valve <NUM>. However, the valve becomes obsolete, having been replaced with a transcatheter valve, and so this loss of function is of no consequence. The wireform maintains the upstanding commissure posts of the expanded valve in roughly the same relative circumferential locations as when they were functional, which are intermediate the surrounding coronary ostia, and thus valve expansion will not end up blocking critical blood flow to the coronary arteries.

Another concept for limiting the expansion of prosthetic heart valves is shown in <FIG>, which is a sectional view through an alternative heart valve <NUM> also having a dual wireform assembly where a lower wireform <NUM> is a braided cable. As before, the heart valve <NUM> has a cloth-covered upper wireform <NUM> and a plurality of leaflets <NUM> supported thereby. An outer sealing ring <NUM> includes a taller axial portion <NUM> at each of the commissure locations, which may be a molded silicone element or folded cloth or the like. Although not shown, commissure inserts such as those shown above at <NUM> may be utilized, and an outer cloth covering is not shown for clarity.

The lower wireform <NUM> is preferably shaped similarly to the lower wireform <NUM> described above, and is shown in two different embodiments in <FIG>. Namely, the wireform <NUM> has an undulating shape with truncated peaks <NUM> in between arcuate cusp sections <NUM>. The braided wireform <NUM> is preferably formed from an elongated braided cable or wire which is joined together at its free ends at either a weld <NUM> as seen in <FIG>, or at a crimp <NUM> such as seen in <FIG>. A weld <NUM> is typically used in the cusp sections <NUM>, while a crimp <NUM> would be preferred at one of the peaks <NUM>. Although not shown, the braided cable or wire is preferably held in the undulating shape as shown, such as with the use of a mandrel or other such manufacturing form, and heat set so that the shape is imparted to the cable. In a preferred embodiment, the braided wireform <NUM> is made of a plurality of braided strands of Nitinol that have been heat set. In this way, the wireform <NUM> provides a relatively stable peripheral base for the valve <NUM>, but is also relatively flexible and permits post-implant expansion. In other embodiments, the braided wireform <NUM> comprises strands manufactured from another material, for example, stainless steel or cobalt-chromium. In other embodiments, the cable comprises a polymer, for example, ultra-high-molecular-weight polyethylene (UHMWPE, e.g., Spectra® (Honeywell, Morristown, New Jersey) or Dyneema® (Heerlen, Netherlands) UHMWPE)) or polyaramid (e.g., Kevlar® (DuPont, Wilmington, Delaware) or Twaron® (Teijin, Arnhem, Netherlands) aramid). Other embodiments of the cable comprise a composite including at least two of any of these materials. Some examples of the braided wireform <NUM> are manufactured in an annular shape, and consequently, do not include a weld or crimp. Examples of suitable manufacturing methods include weaving, knitting, or braiding.

In contrast to the lower wireform <NUM> described above, the braided wireform <NUM> is desirably embedded within the sealing ring <NUM>, although the lower wireform <NUM> may also be embedded within the sealing ring. In one embodiment, the sealing ring <NUM> is a molded silicone element having the braided wireform <NUM> co-molded in an underside thereof. As mentioned, the assembly of the wireform <NUM> and sealing ring <NUM> may be covered with fabric and then joined to the upper wireform <NUM> and leaflets <NUM> via sutures. In <FIG>, the cable <NUM> is disposed directly below the wireform <NUM>. In other embodiments, the cable and wireform are radially offset. For example, as discussed above in connection with the lower wireform <NUM>, the wireform <NUM> can nest within a cable with a larger diameter.

<FIG> is a partially cutaway view of another exemplary prosthetic heart valve <NUM> having an expandable frame <NUM> attached to an inflow end, and <FIG> is an elevational view of the heart valve where only the expandable frame is shown in solid lines. As described above, the heart valve <NUM> includes an undulating wireform <NUM> that supports a plurality of flexible leaflets <NUM>. Element number <NUM> refers to an inner support member which is adapted for post-implant expansion. That is, the support member <NUM> may comprise the lower wireforms <NUM>, as described above, or may be a band structure which has at least one section adapted to expand from use of a dilatation balloon.

The addition of the expandable frame <NUM> creates a "hybrid" type of prosthetic heart valve in that the upper portion is constructed similar to a surgical valve, while the lower frame structure <NUM> is expandable to help in anchoring the valve in place. One specific commercial prosthetic heart valve that is constructed in this manner is one which is sold in conjunction with the Edwards Intuity® valve system from Edwards Lifesciences of Irvine, CA. The Edwards Intuity® valve system comprises a "hybrid" valve incorporating essentially a surgical Perimount® valve, albeit one that is modified for post-implant expansion, and a stainless steel lower frame structure or skirt stent.

<FIG> is a perspective view of the expandable frame <NUM> isolated from the heart valve <NUM>, and <FIG> is a perspective view of the expandable frame after expansion. The frame <NUM> includes an upper undulating strut <NUM> that extends around the entire periphery of the frame and above a plurality of generally V-shaped circumferential struts <NUM> extending between axial struts <NUM>. The undulating strut <NUM> includes three peaks <NUM> that generally conform to the undulating shape of the inflow end of the heart valve <NUM>, as best seen in <FIG>. In other words, the three peaks <NUM> correspond to the three commissures <NUM> of the valve. An absence of the vertical struts <NUM> immediately below each of the three peaks <NUM> creates a space or void <NUM>. Due to the upper curvature of the peaks <NUM>, this permits the undulating strut <NUM> to expand outward such as seen in <FIG> upon application of a dilatory force within the hybrid prosthetic valve.

Claim 1:
A prosthetic heart valve (<NUM>) adapted for post-implant expansion and having an inflow end and an outflow end, comprising:
an upper wireform (<NUM>) undulating around a central axis with three upstanding commissure posts (<NUM>) extending in an outflow direction alternating with three arcuate inflow cusps (<NUM>), and a fabric covering around the entire upper wireform (<NUM>);
a lower wireform (<NUM>) undulating around the central axis with three truncated peaks (<NUM>) extending in an outflow direction alternating with three arcuate inflow cusp sections (<NUM>), and a fabric covering around the entire lower wireform (<NUM>), the lower wireform (<NUM>) being positioned axially below the upper wireform (<NUM>) with the three truncated peaks (<NUM>) being aligned under three upstanding commissure posts (<NUM>) of the upper wireform (<NUM>), and wherein the truncated peaks (<NUM>) have an axial height of between about <NUM>-<NUM>% of the commissure posts (<NUM>);
three flexible leaflets (<NUM>) having outer arcuate cusp edges attached between the inflow cusps (<NUM>) of the upper wireform (<NUM>) and the inflow cusp sections (<NUM>) of the lower wireform (<NUM>) and outer tabs (<NUM>) that extend outward between the commissure posts (<NUM>) of the upper wireform (<NUM>) and the truncated peaks (<NUM>) of the lower wireform (<NUM>) and are secured to the fabric covering around the upper wireform (<NUM>), the flexible leaflets (<NUM>) being configured to ensure one-way blood flow through the heart valve (<NUM>), and
wherein the inflow cusps (<NUM>) of the upper wireform (<NUM>) and the inflow cusp sections (<NUM>) of the lower wireform (<NUM>) together define an implant circumference having a first diameter (D1), and wherein the upper and lower wireforms (<NUM>, <NUM>) permit expansion of the heart valve (<NUM>) from the first diameter (D1) to a second diameter (d1) no greater than <NUM> larger than the first diameter (D1) upon application of an outward dilatory force from within the heart valve (<NUM>) substantially larger than forces associated with normal physiological cycling, and wherein the lower wireform (<NUM>) has a shallow undulating shape that flattens out and prevents expansion of the heart valve (<NUM>) beyond the second diameter (d1).