Patent Description:
Diseased mitral and tricuspid valves frequently need replacement or repair. The mitral and tricuspid valve leaflets or supporting chordae may degenerate and weaken or the annulus may dilate leading to valve leak. Mitral and tricuspid valve replacement and repair are frequently performed with aid of an annuloplasty ring, used to reduce the diameter of the annulus, or modify the geometry of the annulus in any other way, or aid as a generally supporting structure during the valve replacement or repair procedure. The annuloplasty ring is typically implanted around the annulus of the heart valve.

A problem with prior art annuloplasty implants is to achieve correct positioning at the heart valve and fixate the implant in the correct position. Suturing devices for annuloplasty implants have disadvantages that makes it difficult to suture in the correct position, thereby resulting insufficient suturing strength, and also in a very time-consuming procedure, which increases the risks for the patient. Furthermore, suturing devices are often not sufficiently compact for catheter based procedures. The use of clips for positioning annuloplasty implants is also associated with challenges, in particular when implanting helix rings that are to be positioned on either side of a heart valve. Insufficient fixation of such implant lead to traumatic effects since the fixation structure must ensure the correct position of the device over time. A further problem in the prior art is thus also to achieve a reliable fixation at the annulus of the heart valve. An annuloplasty implant is intended to function for years and years, so it is critical with long term stability in this regard.

<CIT> discloses an annuloplasty device comprising first and second support rings being configured to be arranged as a coil in a first configuration around an axial direction. The first and second support rings are configured to be arranged on opposite sides of native heart valve leaflets of a heart valve. An anterior portion, and posterior bows are disclosed and the supports have fastening units.

The above problems may have dire consequences for the patient and the health care system. Patient risk is increased.

Hence, an improved annuloplasty implant would be advantageous and in particular allowing for avoiding more of the above mentioned problems and compromises, and in particular ensuring secure fixation of the annuloplasty implant, during the implantation phase, and for long-term functioning, in addition to a less complex procedure, and increased patient safety. A related method of manufacturing would also be advantageous.

Accordingly, examples of the present invention preferably seek to mitigate, alleviate or eliminate one or more deficiencies, disadvantages or issues in the art, such as the above-identified, singly or in any combination by providing a device according to the appended patent claims.

According to a first aspect an annuloplasty device is provided comprising first and second support rings having a coiled configuration in which the first and second support rings are arranged as a coil around a central axis, wherein the first and second support rings are configured to be arranged on opposite sides of native heart valve leaflets of a heart valve, wherein the first and/or second support ring comprises a plurality of sides forming a non-circular cross-section of the first and/or second support ring, wherein the cross-section varies along a longitudinal direction of the first and/or second support ring.

According to a second aspect a method of manufacturing an annuloplasty device, comprising providing a sheet of a biocompatible metal alloy, cutting first and second support sections from the sheet, arranging the first and second support sections in a coiled configuration so that the first and second support sections form first and second support rings arranged as a coil around a central axis, heating the first and second support rings to heat-set the coiled configuration of the annuloplasty device.

According to a third aspect , not part of the invention, a method of repairing a defective heart valve is provided comprising positioning a second support ring of an annuloplasty device on a ventricular side of the heart valve, and positioning a first support ring of the annuloplasty device on an atrial side of the heart valve, the first and second support rings are arranged as a coil around a central axis on opposite sides of native heart valve leaflets of the heart valve, the first and/or second support ring comprises a plurality of sides forming a non-circular cross-section of the first and/or second support ring, wherein the cross-section varies along a longitudinal direction of the first and/or second support ring.

Further examples of the invention are defined in the dependent claims, wherein features for the second aspect are as for the first aspect mutatis mutandis.

Some examples of the disclosure provide for a facilitated positioning of an annuloplasty implant at a heart valve.

Some examples of the disclosure provide for a facilitated fixation of an annuloplasty implant at a heart valve.

Some examples of the disclosure provide for a less time-consuming fixation of an annuloplasty to a target site.

Some examples of the disclosure provide for securing long-term functioning and position of an annuloplasty implant.

Some examples of the disclosure provide for a more secure implantation of an annuloplasty implant in narrow anatomies.

Some examples of the disclosure provide for an annuloplasty device with an increased retention force at the heart valve.

Some examples of the disclosure provide for a facilitated manufacturing of an annuloplasty device.

These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which.

The following description focuses on an embodiment of the present invention applicable to cardiac valve implants such as annuloplasty rings. However, it will be appreciated that the invention is not limited to this application but may be applied to many other annuloplasty implants and cardiac valve implants including for example replacement valves, and other medical implantable devices.

<FIG> schematically illustrates an example of an annuloplasty device <NUM> comprising a first support ring <NUM> and second support ring <NUM> which are adapted to be arranged as a coil, i.e. in a helix-shape, in a coiled configuration around a central axis <NUM>, as illustrated in the top-down view of <FIG> and the side view of <FIG>. The device <NUM> is arranged in the coiled configuration at least when in a relaxed state of the material from which the device <NUM> is formed, i.e. free from outside forces acting upon the device <NUM>. The coil-shaped device <NUM> has two free ends <NUM>, <NUM>'. The first and second support rings <NUM>, <NUM>, and the respective free ends <NUM>, <NUM>', are configured to be arranged on opposite sides of native heart valve leaflets <NUM> of a heart valve, as illustrated in e.g. the side view of <FIG>. As shown in <FIG>, the first support ring <NUM> may be arranged on an atrial side of the heart valve, and the second support ring <NUM> may be arranged on a ventricular side. The first support ring <NUM> may thus extend along the annulus of the heart valve on the atrial side. The first and second support rings <NUM>, <NUM>, are connected to form a coil- or helix shaped ring, as an integral continuous ring. The coil extends through the valve opening at a commissure thereof. The first and second support rings <NUM>, <NUM>, may thus assume the coiled configuration also when in an implanted state. As explained further below, the device <NUM> may comprise a shape-memory material, so that the device <NUM> re-assumes the coiled configuration after having been delivered from a catheter (not shown) to the target site, after having been temporarily restrained in an elongated configuration of the catheter. The annuloplasty device <NUM>, i.e. annuloplasty implant <NUM>, may comprise a shape memory material, such as NiTiNol, or another suitable biocompatible alloy that can be heat-set in defined shapes, i.e. in a defined relaxed shape in absence of outside acting forces, as described further below, in a heat treatment procedure. The annuloplasty device <NUM> may pinch the tissue of the valve leaflets <NUM>, between the first and second support rings <NUM>, <NUM>, i.e. with forces acting parallel with the central axis <NUM>.

The device <NUM> may comprise a shape-memory material, so that the first and second rings <NUM>, <NUM>, assumes the first configuration after having been ejected from a delivery catheter (not shown). While positioned in the delivery catheter the device <NUM> may be stretched in an elongated shape. Alternatively, the device <NUM> may be arranged in the coiled configuration when being delivered to the target site, in which case it may be implanted at the target site for example by incision between the ribs or by opening the chest. The present disclosure, and the associated advantages described for the various examples, applies to both such variants of the device <NUM>.

The first and/or second support ring <NUM>, <NUM>, comprises a plurality of sides <NUM>, <NUM>' forming a non-circular cross-section <NUM> of the first and/or second support ring <NUM>, <NUM>. <FIG>, <FIG> show examples of such non-circular cross-sections <NUM>. Different cross-section lines A-A, B-B, C-C, and D-D are indicated in <FIG>. The cross-section <NUM> of the first and/or second support ring <NUM>, <NUM>, along the aforementioned cross-section lines may correspond to any of the examples in <FIG>, <FIG>.

The cross-section <NUM> varies along a longitudinal direction <NUM> of the first and/or second support ring <NUM>, <NUM>. Having a non-circular shape provides for increasing the compression force between the first and second rings <NUM>, <NUM>, in the coiled configuration while maintaining a compact cross-sectional profile of the first and second rings <NUM>, <NUM>. The dimensions of the sides <NUM>, <NUM>', may be varied in order to provide for an optimized bending resistance of the support rings <NUM>, <NUM>. Varying the aforementioned dimensions along the length of the first and second support rings <NUM>, <NUM>, i.e. along the longitudinal direction <NUM>, allows for varying the flexibility of the rings <NUM>, <NUM>, along the longitudinal direction <NUM> and be customized to different anatomical positions around the annulus of the heart valve. This provides for better accommodating movement of the tissue which may be greater at localized sections of the annulus, while other sections may have an increased rigidity for a stronger pinching effect between the first and second support rings <NUM>, <NUM>. A more secure and robust positioning of the device <NUM> may thus be provided and improved long-term functioning. A varying cross-section <NUM> provides also for optimizing the flexibility with respect to the delivery and positioning phase of the annuloplasty device <NUM>. portions of the first and second support rings <NUM>, <NUM>, which are subject to the most bending movement when being inserted in a delivery catheter (not shown) may have a cross-section which increases the flexibility. Those portions may be the commissure sections <NUM>, <NUM>', <NUM>", as described further below. Increasing the flexibility of those sections allows for reducing the force needed to advance the annuloplasty device <NUM> in the delivery catheter and facilitating the deployment of the annuloplasty device <NUM> at the target site. The implantation procedure is thus facilitated. Other portions of the first and second support rings <NUM>, <NUM>, such as the posterior bows <NUM>, <NUM>', may simultaneously have a different cross-section which provides for a decreased flexibility and a greater pinching force between the rings <NUM>, <NUM>, in the axial direction <NUM>. <FIG> shows a perspective view of an annuloplasty device <NUM> comprising first and second support rings <NUM>, <NUM>. The first and/or second support ring <NUM>, <NUM>, may have a varying non-circular cross-section <NUM> as described above, providing for the aforementioned advantageous benefits.

The cross-section <NUM> may be essentially rectangular, as shown in the example of <FIG>. This may provide for particularly advantageous mechanical characteristics for increasing the compression force between the first and second support rings <NUM>, <NUM>, while maintaining a compact cross-section. The length of the sides <NUM>, <NUM>', may vary as exemplified in <FIG>, and it is conceivable that the length of the sides <NUM>, <NUM>', are varied for optimization to different applications, and also varied along the length of the support rings <NUM>, <NUM>, as elucidated above. It should be understood that the cross-sections <NUM> in <FIG> are examples and that other variations of the cross-section <NUM> of the first and/or second support ring <NUM>, <NUM>, are conceivable.

The area of the cross-section <NUM> varies along the longitudinal direction <NUM>. <FIG> show an example of a varying area of the cross-section <NUM>, where the area of the cross-section <NUM> in <FIG> is less compared to the areas of the cross-section <NUM> in <FIG>. The first and/or second support ring <NUM>, <NUM>, may have two different cross-sections <NUM>, such as exemplified in <FIG>, along different cross-sectional lines A-A, B-B, C-C, D-D as exemplified in <FIG>. For example, the area of the cross-section <NUM> along A-A or C-C may be less than the area of the cross-section <NUM> along B-B or D-D. This may provide for increased flexibility along A-A and/or C-C, corresponding to commissure sections <NUM>', <NUM>, compared to the sections at B-B and/or D-D, corresponding to posterior bows <NUM>, <NUM>'. This may provide for the advantageous benefits as described above. The transition between the different areas is gradual along the longitudinal direction <NUM>.

The shape of the cross-section <NUM> may vary along the longitudinal direction <NUM>. <FIG> are schematic examples of such varying shape. Turning to e.g. <FIG>, the length of the sides <NUM> extending in direction <NUM>' being parallel with the central axis <NUM> may be varied. <FIG> show longer sides <NUM> in the aforementioned direction compared to the cross-section in <FIG>. Increasing the dimension of the sides <NUM> to create a taller profile may provide for increasing the bending resistance along the axial direction <NUM>, compared to the thinner profile in <FIG> in this direction. The area of the cross-sections <NUM> in <FIG> may be similar or the same, but the varying the shape allows for tailoring the bending resistance while maintaining the overall structural rigidity provided by the unchanged cross-sectional area. Different portions of the first and/or second support rings <NUM>, <NUM>, may thus be optimized according to their intended positions along the heart valve annulus and in what direction the forces should act to provide a strong retention force but also compliance to the anatomy and the dynamic motions in the heart. The first and/or second support ring <NUM>, <NUM>, may have two different cross-sections <NUM>, such as exemplified in <FIG>, along different cross-sectional lines A-A, B-B, C-C, D-D as exemplified in <FIG>.

Turning to <FIG>, the first support ring <NUM> may comprise a first posterior bow <NUM> and a first anterior portion <NUM>. The second support ring <NUM> may comprise a second posterior bow <NUM>' and a second anterior portion <NUM>'. The first and second posterior bows <NUM>, <NUM>', are adapted to conform to a posterior aspect of said heart valve, and the first and second anterior portions <NUM>, <NUM>', are adapted to conform to an anterior aspect of said heart valve. The first posterior bow <NUM> transitions to the first anterior portion <NUM> over a first commissure section <NUM>. The first anterior portion <NUM> transitions to the second posterior bow <NUM>' over a second commissure section <NUM>'. The second posterior bow <NUM>' transitions to the second anterior portion <NUM>' over a third commissure section <NUM>".

Any of the first, second and third commissure sections <NUM>, <NUM>', <NUM>" may have a cross-section which has an area and/or shape which is different than an area and/or shape of the cross-section <NUM> of any of the first posterior bow <NUM>, the second posterior bow <NUM>', the first anterior portion <NUM>, and the second anterior portion <NUM>'. The bending radius of the first, second and third commissure sections <NUM>, <NUM>', <NUM>", is less than the bending radius of any of the first posterior bow <NUM>, the second posterior bow <NUM>', the first anterior portion <NUM>, and the second anterior portion <NUM>'. Having a different area and/or shape of the cross-section <NUM> at the first, second and/or third commissure section <NUM>, <NUM>', <NUM>", compared to the aforementioned portions may thus provide for optimizing the dynamic behavior of the annuloplasty device <NUM> at <NUM>, <NUM>', <NUM>". to facilitate stretching the annuloplasty device <NUM> in a delivery catheter or positioning the annuloplasty device <NUM> at opposite sides of the heart valve, where the first and second support rings <NUM>, <NUM>, gradually assume the defined heat-set coiled configuration upon ejection from the delivery catheter. Also, the pinching force may be optimized to the particular application, since the first commissure sections <NUM>, in the example of <FIG>, is also the transition point at the commissure connecting the first and second support rings <NUM>, <NUM>, through the heart valve opening. The area and/or shape of the first commissure sections <NUM> may thus be varied to provide such pinching force between the rings <NUM>, <NUM>. in one example, the area and/or shape of the cross-section <NUM> at the second and third commissure sections <NUM>', <NUM>", may provide for increased flexibility, for facilitated deployment through a catheter, compared to the first commissure section <NUM>, which may instead be optimized for increasing the pinching effect between the rings <NUM>, <NUM>, in the axial direction <NUM> (<FIG>).

In one example, any of the first, second and third commissure sections <NUM>, <NUM>', <NUM>" may have a cross-section <NUM> which has an area which is less than an area of the cross-section <NUM> of any of the first posterior bow <NUM>, the second posterior bow <NUM>', the first anterior portion <NUM>, and the second anterior portion <NUM>'. This may provide for increasing the flexibility at any of the first, second and third commissure sections <NUM>, <NUM>', <NUM>", compared to the aforementioned portions, to provide for the advantageous benefits as mentioned above.

The first and/or second anterior portion <NUM>, <NUM>', may have a cross-section <NUM> which has an area and/or shape which is different than an area and/or shape of the cross-section <NUM> of the first and/or second posterior bow <NUM>, <NUM>'. The pinching force in the axial direction <NUM> and the flexibility of the annuloplasty device <NUM> during delivery and implantation may thus be optimized by tailoring the cross-section along the anterior portions <NUM>, <NUM>', and the posterior bows <NUM>, <NUM>'. In one example, it may be desirable to have a greater pinching force between the rings <NUM>, <NUM>, along the posterior bows <NUM>, <NUM>', compared to the anterior portions <NUM>, <NUM>'. the tissue may in some cases be more sensitive along the anterior portions <NUM>, <NUM>', and a greater flexibility along the latter portions may thus be desirable. As elucidated above, the flexibility may be increased by reducing the length of the sides <NUM> extending parallel with the central axis, and/or by generally reducing the area of the cross-section <NUM>.

The first anterior portion <NUM> may have a cross-section <NUM> which has an area and/or shape which is different than an area and/or shape of the cross-section <NUM> of the second anterior portion <NUM>'. The anatomy and the dynamic characteristics of the heart valve motions may be different on the atrial and ventricular sides of the heart valve. It may thus be advantageous to have different cross-sections <NUM> on first and second anterior portions <NUM>, <NUM>', to provide the desired compliance to the anatomy while having the rigidity to exert a compressive force which anchors the annuloplasty device <NUM> in place.

Similarly, the first posterior bow <NUM> may have a cross-section <NUM> which has an area and/or shape which is different than an area and/or shape of the cross-section <NUM> of the second posterior bow <NUM>', to accommodate variations in the anatomy on the ventricular and atrial sides.

The cross-section <NUM> may be elongated in a direction <NUM>' extending essentially in parallel with the central axis <NUM>. This provides for increasing the compression force in a direction parallel with the central axis <NUM>, while allowing for increasing the flexibility in a direction perpendicular to the central axis <NUM>. Having an increased flexibility perpendicular to the central axis <NUM> may facilitate bending the first and second support rings <NUM>, <NUM>, to an elongated straight configuration for insertion in a delivery catheter. Hence, such elongated "band-profile" as exemplified in <FIG>, may provide for increasing the compression force while also allowing for a facilitated implantation via a delivery catheter (not shown). The elongated profile may vary, as exemplified in <FIG>, to adapt the flexibility and retention as described above. Thus, the first and/or second support ring <NUM>, <NUM>, may have two different cross-sections <NUM>, such as exemplified in <FIG>, along different cross-sectional lines A-A, B-B, C-C, D-D as exemplified in <FIG>.

Thus, the cross-section <NUM> may be rectangular so that the longest sides <NUM> of the rectangular shape extend essentially in parallel with the central axis <NUM>.

<FIG> show another example where the cross-section <NUM> is elongated but the short side <NUM> of the rectangle is perpendicular to the direction <NUM>'. Direction <NUM>' is parallel with the central axis <NUM>. Such alignment of the short side <NUM> provides for increased flexibility for bending in the axial direction <NUM>, which may be desirable in some applications. The area and/or shape of the cross-section <NUM> may vary as illustrated in <FIG>, while maintaining the same alignment of the generally elongated shape of the cross-section <NUM>. the flexibility along the central axis <NUM> may be increased even further at some portions of the annuloplasty device <NUM> by reducing the height of the sides <NUM> as schematically indicated in <FIG>, compared to <FIG>. The first and/or second support ring <NUM>, <NUM>, may have two different cross-sections <NUM>, such as exemplified in <FIG>, along different cross-sectional lines A-A, B-B, C-C, D-D as exemplified in <FIG>.

The first support ring <NUM> may have a cross-section <NUM> which has an area and/or shape which is different than an area and/or shape of the cross-section <NUM> of the second support ring <NUM>. The variation between the first and second rings <NUM>, <NUM>, may be exemplified by any of the above discussed variations.

The first and second support rings <NUM>, <NUM>, may be formed from a shape-memory material. The first and second support rings <NUM>, <NUM>, may have an elongated delivery configuration for advancement in a catheter, as described above. The first and second support rings <NUM>, <NUM>, may thus assume the coiled configuration again, after being ejected from a delivery catheter.

<FIG> shows a perspective view of an annuloplasty device <NUM> comprising first and second support rings <NUM>, <NUM>. The first and/or second support ring <NUM>, <NUM>, may have a varying non-circular cross-section <NUM> as described above in relation to <FIG>, thus providing for the aforementioned advantageous benefits.

A method <NUM> of manufacturing an annuloplasty device is provided. The method <NUM> is schematically illustrated in <FIG>, in conjunction with <FIG>. The order in which the steps are described should not be construed as limiting, and it is conceivable that the order of the steps may be varied depending on the particular procedure. The method <NUM> comprises providing <NUM> a sheet (not shown) of a biocompatible metal alloy. The method <NUM> comprises cutting <NUM> first and second support sections (not shown) from the sheet. The method <NUM> comprises arranging <NUM> the first and second support sections in a coiled configuration so that the first and second support sections form first and second support rings <NUM>, <NUM>, arranged as a coil around a central axis <NUM>, as schematically illustrated in <FIG>. The method <NUM> comprises heating <NUM> the first and second support rings <NUM>, <NUM>, to heat-set the coiled configuration of the annuloplasty device <NUM>. This provides for an effective, cost-efficient and facilitated manufacturing method of the annuloplasty device <NUM>. The cutting of the support rings <NUM>, <NUM> (to be formed) from the sheet may be provided by laser cutting, punching, or any other method for separating the desired support sections from the sheet.

A method <NUM> of repairing a defective heart valve is provided. The method <NUM> is schematically illustrated in <FIG>, in conjunction with <FIG>. The order in which the steps are described should not be construed as limiting, and it is conceivable that the order of the steps may be varied depending on the particular procedure. The method <NUM> comprises positioning <NUM> a second support ring <NUM> of an annuloplasty device <NUM> on a ventricular side of the heart valve. The method <NUM> comprises positioning <NUM> a first support ring <NUM> of the annuloplasty device <NUM> on an atrial side of the heart valve. The first and second support rings are arranged as a coil around a central axis <NUM> on opposite sides of native heart valve leaflets of the heart valve. The first and/or second support ring <NUM>, <NUM>, comprises a plurality of sides <NUM>, <NUM>' forming a non-circular cross-section <NUM> of the first and/or second support ring <NUM>, <NUM>. The cross-section <NUM> varies along a longitudinal direction <NUM> of the first and/or second support ring <NUM>, <NUM>. The method <NUM> thus provides for the advantageous benefits as described above with respect to the annuloplasty device <NUM> and <FIG>.

The first <NUM> and/or second support <NUM> may comprise a shape memory material, such as NiTiNol, or another suitable biocompatible alloy that can be heat-set in defined shapes, in a heat treatment procedure. The shape-memory material may comprise a material having more than one phase, so that the shape of the support rings <NUM>, <NUM>, may be actively varied as described above. The shape memory material can be conceived as any material that is able to change shape as desired, in response to outside interaction, for example with an energy source, such as providing heat and/or electromagnetic energy, that can be transferred to the device <NUM> to change its shape. It is also conceivable that the shape of the device <NUM> can be affected by direct mechanical manipulation of the curvature of the first <NUM> and/or second support <NUM>, e.g. by transferring a force or torque to the device <NUM> via a delivery device. Via the various mentioned shape-affecting procedures the device <NUM> may assume an elongated delivery configuration for advancement in a catheter, an initial shape when positioned in a coiled configuration along the annulus of the valve, i.e. the first configuration, and also an activated shape such as the contracted state described above for enhancing the strength of the fixation at an annulus of the heart valve.

The support rings <NUM>, <NUM>, may be formed from a solid rod or other solid elongated structure, having various cross-sections, such as circular, elliptic, rhombic, triangular, rectangular etc. The support rings <NUM>, <NUM>, may be formed from a hollow tube, or other hollow structures with the mentioned cross-sections. The support rings <NUM>, <NUM>, may be formed from a sandwiched laminate material, comprising several layers of different materials, or different layers of the same material. The support rings <NUM>, <NUM>, may be formed from a stent or a stent-like structure, and/or a braided material. The support rings <NUM>, <NUM>, may be formed from a braid of different materials braided together, or from a braid of the same material. As mentioned, the support rings <NUM>, <NUM>, may be formed from NiTinol, or another suitable bio-compatible material. The surfaces of the first and second support rings <NUM>, <NUM>, may be provided with other materials and/or treated with different materials and/or structured to enhance resistance to breaking in case the material is repeatedly bent.

The first and second support rings <NUM>, <NUM>, may have an elongated delivery configuration for advancement in a catheter, and an implanted shape in the above described contracted state.

Claim 1:
An annuloplasty device (<NUM>) comprising
first (<NUM>) and second (<NUM>) support rings having a coiled configuration in which the first and second support rings are arranged as a coil around a central axis (<NUM>), wherein the first and second support rings are configured to be arranged on opposite sides of native heart valve leaflets (<NUM>) of a heart valve,
wherein the first and/or second support ring comprises a plurality of sides (<NUM>, <NUM>') forming a non-circular cross-section (<NUM>) of the first and/or second support ring, wherein the cross-section varies along a longitudinal direction (<NUM>) of the first and/or second support ring,
wherein the first support ring comprises a first posterior bow (<NUM>) and a first anterior portion (<NUM>),
the second support ring comprises a second posterior bow (<NUM>') and a second anterior portion (<NUM>'),
the first and second posterior bows are adapted to conform to a posterior aspect of said heart valve, and the first and second anterior portions are adapted to conform to an anterior aspect of said heart valve,
the first posterior bow transitions to the first anterior portion over a first commissure section (<NUM>),
the first anterior portion transitions to the second posterior bow over a second commissure section (<NUM>'),
the second posterior bow transitions to the second anterior portion over a third commissure section (<NUM>"),
wherein any of the first, second and third commissure sections (<NUM>, <NUM>', <NUM>") have a first cross-section which has an area and/or shape which is different than an area and/or shape of a second cross-section of any of the first posterior bow (<NUM>), the second posterior bow (<NUM>'), the first anterior portion (<NUM>), and the second anterior portion (<NUM>'), wherein the first cross-section transitions gradually to the second cross-section along the longitudinal direction.