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.

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

<CIT> discloses an annuloplasty implant comprising first and second supports adapted to be arranged in a coiled configuration. The first and second supports may be separated with a first pitch distance in an axial direction, in the coiled configuration and may comprise a shape-memory material configured to assume a contracted state having a second pitch distance being shorter than the first pitch distance.

<CIT> discloses an annuloplasty implant comprising first and second support rings adapted to be arranged in a coiled configuration. Fastening units may be arranged on a first posterior bow for interlocking with a second posterior bow.

Hence, an improved annuloplasty implant or device 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 device, during the implantation phase, and for long-term functioning, in addition to a less complex procedure, and increased patient safety. A related method 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 according to claim <NUM>.

Further examples of the invention are defined in the dependent claims.

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

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

Some examples of the disclosure provide for a reduced risk of damaging the anatomy of the heart such as the annulus or the valve leaflets.

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

Some examples of the disclosure provide for an annuloplasty device with improved accommodation to the anatomy of a heart valve.

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

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.

<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 <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 second support ring <NUM> is also shown with dashed lines in the top-down views of <FIG>, where the valve leaflets have been omitted). The second support ring <NUM> is illustrated with a dashed line and is in these examples arranged on the ventricular side of the heart valve, whereas the first support ring <NUM> is arranged on the atrial side of the heart valve (shown with solid line). 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 <NUM>, <NUM>', thereof, as schematically illustrated in <FIG>. 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. <FIG> is a schematic illustration of the annuloplasty device <NUM> when in such elongated stretched state. 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 annuloplasty device <NUM> may optionally comprise retention units <NUM>, <NUM>', as schematically illustrated in the perspective views of e.g. <FIG>, <FIG>, and side views of <FIG>, <FIG>, <FIG>, <FIG> and cross-sectional views of <FIG> (i.e. looking along the longitudinal direction <NUM> in which the first and second rings <NUM>, <NUM>, extend), and <FIG>, <FIG>. <FIG> show examples where a plurality of retention units <NUM>, <NUM>', are arranged on the first and second support rings <NUM>, <NUM>. The example in <FIG> show the device <NUM> in an elongated stretched configuration, e.g. as arranged while being restrained in a catheter. However, as mentioned above, the device <NUM> assumes the coiled shape when released from the catheter, whereupon the retention units <NUM>, <NUM>', may engage the tissue on the atrial and ventricular sides of the heart valve, as exemplified in <FIG> and as described further below. The retention units <NUM>, <NUM>', are configured to engage the tissue of the valve and anchor the device <NUM> at the valve. The first support ring <NUM> may comprise first retention units <NUM>, and the second support ring <NUM> may comprise second retention units <NUM>'.

The first support ring <NUM> transitions to the second support ring <NUM> over a transition section <NUM>, as illustrated in e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>. The transition section <NUM> is adapted to be arranged at a commissure <NUM>, <NUM>', of the heart valve leaflets, e.g. at a commissure <NUM>' as illustrated in <FIG>. The first and second support rings <NUM>, <NUM>, extend in respective first and second coil planes <NUM>', <NUM>', being essentially perpendicular to the central axis <NUM>. The transition section <NUM> may bend at least partly along the central axis <NUM> so that the first coil plane <NUM>' is separated a distance (d<NUM>) from the second coil plane <NUM>' along the central axis <NUM> (i.e. along a direction parallel to the central axis) at the transition section <NUM>. Having such transition section <NUM> where the coil planes <NUM>', <NUM>', are locally displaced a distance (d<NUM>), and at a position corresponding to the location of the commissure <NUM>, <NUM>', provides for improved accommodation of the first and second support rings <NUM>, <NUM>, to the anatomy at the opposite sides of the valve, in particular as the heart beats. Having a step-down in the coil planes <NUM>', <NUM>', or an "S-shape", or "Z-shape", of the support rings <NUM>, <NUM>, at the transition section <NUM> due to separation distance (d<NUM>) provides for a better coaptation of the first and second support rings <NUM>, <NUM>, at the commissure <NUM>, <NUM>'. the risk of having the moving valve leaflets pulling on any of the support rings <NUM>, <NUM>, at the commissure <NUM>, <NUM>', is minimized because the first coil plane <NUM>' of the first support ring <NUM> on the atrial side transitions to the second coil plane <NUM>' of the second support ring <NUM> over a reduced distance at the transition section <NUM> due to the displacement (d<NUM>) (i.e. a local section <NUM> of increased pitch or rise of the coil formed by the adjacent support rings <NUM>, <NUM>). This means that the first and second support rings <NUM>, <NUM>, may conform better to the two opposite sides of the valve close to the commissure <NUM>, <NUM>'. The annuloplasty device <NUM> may thus be secured at the valve in a safer manner, while the risk of dislocations is minimized. The position of the transition section <NUM> may be varied depending on which commissure <NUM>, <NUM>', the first/second support rings <NUM>, <NUM>, extend through the valve leaflets. The transition section <NUM> may thus have an increased slope or pitch relative the central axis <NUM> compared to the remaining portions of the first and second support rings <NUM>, <NUM>.

The length of the transition section <NUM> may in one example correspond to approximately an off-set distance <NUM> between free ends <NUM>, <NUM>', as schematically illustrated in <FIG>, <FIG>, <FIG>. In one example the transition section <NUM> may be arranged after the first support ring <NUM> forms essentially one complete loop, as exemplified in <FIG>.

The transition section <NUM> may bend at least partly along a radial direction (R), where the radial direction (R) is perpendicular to the central axis <NUM>, so that the transition section <NUM> is concave towards the radial direction (R). <FIG> and <FIG> illustrate examples of such concave bend, or "C-curve", of the transition section <NUM> towards the radial direction (R). This provides for further improving the coaptation of the first and second support rings <NUM>, <NUM>, to the valve anatomy close to the commissure <NUM>, <NUM>'. The risk of having a disadvantageous force transfer or friction between the moving valve leaflets and any of the support rings <NUM>, <NUM>, at the commissure <NUM>, <NUM>', is minimized. The first and second support rings <NUM>, <NUM>, may extend along the annulus as far as possible while extending through the commissure <NUM>, <NUM>', with minimized impact on the valve motion, as the concave bend of the transition section <NUM> allows for adapting to anatomies where the commissure <NUM>, <NUM>', is located closer to the central axis <NUM> than the annulus. The annuloplasty device <NUM> may thus be secured at the valve in a further improved manner, while the risk of dislocations in the long term is minimized.

The advantageous features of having a transition section <NUM>, as described in relation to e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, above provide for an improved annuloplasty device <NUM> with an improved anchoring into the tissue, also in absence of the below discussed displacement (d) in the relaxed state (<FIG>). In absence of the displacement (d) in the relaxed state, the annuloplasty device <NUM> has a relaxed state corresponding to the illustration in <FIG>. In case the annuloplasty device <NUM> comprises retention units <NUM>, <NUM>', the retention units <NUM>, <NUM>', point in a direction towards eachother in the relaxed state, in absence of the below discussed displacement (d) in the relaxed state.

The first support ring <NUM> comprises a first posterior bow <NUM> and a first anterior portion <NUM>. The second support ring <NUM> comprises 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 the heart valve, i.e. along the posterior leaflet, having a bow-shaped extension. The first and second anterior portions <NUM>, <NUM>', may each have a straighter extension or at least an extension which is less bent than the bow-shaped posterior sides <NUM>, <NUM>'. This is exemplified in e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>. The first and second anterior portions <NUM>, <NUM>', are be-adapted to conform to an anterior aspect of the heart valve, i.e. along an anterior leaflet.

At least part of the first anterior portion <NUM> and/or the second anterior portion <NUM>' may be curved to form a respective concave section <NUM>, <NUM>', being concave towards a radial direction (R), where the radial direction (R) is perpendicular to the central axis <NUM>, as schematically illustrated e.g. in <FIG> and <FIG>. This provides for further improving the accommodation of the first and second support rings <NUM>,<NUM>, to the anatomy of the valve and its annulus. A more secure attachment of the annuloplasty device <NUM> is achieved, and long-term reliability of the implantation, since interference with the natural heart valve movements can be minimized.

The first anterior portion <NUM> may be displaced a distance (l<NUM>) from the second anterior portion <NUM>' along a radial direction (R) so that at least part of the second anterior portion <NUM>' extends with a greater radius (r) from the central axis <NUM> than the first anterior portion <NUM>, as schematically illustrated in e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>. Thus, when the first support ring <NUM> is arranged on the atrial side and the second support ring <NUM> is arranged on the ventricular side, the second anterior portion <NUM>' of the second support ring <NUM> will extend with a greater radius from the central axis <NUM> than the first anterior portion <NUM> of the first support ring <NUM>. This is also exemplified in <FIG>. Having a greater radius of the second support ring <NUM> on the ventricular side provides for an effective pinching of the valve tissue at the aortoseptal wall, and thus a more secure anchoring of the annuloplasty device <NUM>.

As schematically illustrated in e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, the first posterior bow <NUM> may be displaced a distance (I<NUM>) from the second posterior bow <NUM>' along a radial direction (R). The radial direction (R) is perpendicular to the central axis <NUM>. The off-set between the first and second posterior bows <NUM>, <NUM>', provides for an improved fixation of the annuloplasty device <NUM> on a downsized posterior annulus and thus a more effective anchoring of the annuloplasty device <NUM>. At least part of the first posterior bow <NUM> may thus extend with a greater radius (r) from the central axis <NUM> than the second posterior bow <NUM>', as schematically illustrated in e.g. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>. Axis <NUM>' in <FIG>, <FIG>, is parallel with the central axis <NUM>. Having the first support ring <NUM> extending with a greater radius in the radial direction along the posterior bow <NUM> on the atrial side compared to the posterior bow <NUM>' of the second support ring <NUM> on the ventricular side provides for an improved coaptation to the anatomy around the valve on the ventricular side, and thus a more secure anchoring of the annuloplasty device <NUM> and less interference with the native leaflets and chordae. Circumflexing of the chordae may also be facilitated in this case.

In another example however it should be understood that at least part of the second posterior bow <NUM>' may extend with a greater radius (r) from the central axis <NUM> than the first posterior bow <NUM>.

The advantageous features of having displacement distances (I<NUM>, I<NUM>), as described in relation to <FIG>, <FIG>, <FIG>, <FIG>, <FIG> provides for an improved annuloplasty device <NUM> with an improved anchoring into the tissue, also in absence of below discussed displacement (d) in the relaxed state (<FIG>). , in absence of the displacement (d) in the relaxed state, the annuloplasty device <NUM> has a relaxed state corresponding to the illustration in <FIG>.

The first and second support rings <NUM>, <NUM>, may have a separation distance (d) and may be movable relative eachother along the central axis <NUM> so that the separation distance (d) is variable. In one example, the first and second support rings <NUM>, <NUM>, comprises a resilient shape-memory material and may be movable along the central axis <NUM> from a relaxed first state, as illustrated in <FIG>, to a displaced second state, as illustrated in <FIG>. The first state may thus correspond to the defined heat-set shape of the material from which the first and second support rings are formed. In the second state the first and second rings have been forced to a displaced position where the first and second rings have shifted their relative positions along the axial direction <NUM> (<FIG>). There may thus a resilient bias from the second state towards the first state. Thus, the first and second support rings <NUM>, <NUM>, strive to assume the first state when displaced to the second state to pinch the valve leaflets from the opposite sides. In <FIG>, the first support ring <NUM> will strive to move towards the second support ring <NUM>, and vice versa, since in the heat set relaxed shape in <FIG>, the first and second support rings <NUM>, <NUM>, have an inverted relative position with the first support ring <NUM> below the second support ring <NUM>. If the force acting upon the first and second support rings <NUM>, <NUM>, is removed the latter will thus move towards eachother and past eachother so that the inverted relative position in <FIG> is assumed. Having the inverted arrangement of the first and second support rings <NUM>, <NUM>, in the relaxed shape as described above provides for an increased compression force on the valve tissue when the first and second rings <NUM>, <NUM>, are arranged in the second state at opposite sides of the valve leaflets, as further seen in <FIG>. The increased compression force provides for a more secure, robust, and reliable anchoring of the annuloplasty device at the heart valve. This provides for an improved function and safety for the patient, both short term and long term. The implantation procedure may thus be accomplished in less time and with improved control. A secure positioning of the first and second support rings <NUM>, <NUM>, at the opposite sides of the heart valve is facilitated. <FIG> and <FIG> are schematic illustrations of another example where a section of the first and second support rings <NUM>, <NUM>, have an inverted position in the relaxed state, as illustrated by the inverted section <NUM> of the second support ring <NUM>, for providing an increased compression force along the anterior portion <NUM>, <NUM>'.

In one example the first and second support rings <NUM>, <NUM>, have a relaxed first state in which the distance (d) between the first and second support rings <NUM>, <NUM>, is substantially zero.

Turning again to <FIG>, if the first and second support rings <NUM>, <NUM>, comprises retention units <NUM>, <NUM>', then in the first state the first retention units <NUM> extend from the first support ring <NUM> in a direction away from the second support ring <NUM>, as illustrated in <FIG>. Further, in the first state, the second retention units <NUM>' extend from the second support ring <NUM> in a direction away from the first support ring <NUM>, as illustrated in <FIG>. In the second state, the first retention units <NUM> extend from the first support ring <NUM> in a direction towards the second support ring <NUM>, as shown in <FIG>. Further, in the second state, the second retention units <NUM>' extend from the second support ring <NUM> in a direction towards the first support ring <NUM>. The first and second retention units <NUM>, <NUM>', thus produce a retention force at both of said opposite sides. The retention units <NUM>, <NUM>', are directed towards the valve tissue between the first and second support rings <NUM>, <NUM>, from both of the opposite sides.

As mentioned above, although the examples of the annuloplasty device <NUM> as schematically illustrated in <FIG> show the retention units <NUM>, <NUM>', extending in opposite directions away from eachother, to accommodate the change from the relaxed first state, as illustrated in <FIG>, to a displaced second state, as illustrated in <FIG>, it should be understood that the retention units <NUM>, <NUM>', in the examples of <FIG> may be arranged on the first and second support rings <NUM>, <NUM>, to extend towards eachother. In the latter case, the position of the first and second support rings <NUM>, <NUM>, should be inverted with respect to the central axis <NUM>. , in a relaxed state of the annuloplasty device <NUM>, the first support ring <NUM> in the example of <FIG> would instead be placed to the right of the second support ring <NUM>, i.e. so that the positions are shifted with respect to axis <NUM>'.

As mentioned, the first support ring <NUM> may be adapted to be arranged on an atrial side of the heart valve, and the second support ring <NUM> may be adapted to be arranged on a ventricular side of the heart valve, as exemplified in <FIG>. <FIG> show schematic top-down views where the second ring <NUM> is shown with dashed lines and the first ring <NUM> is shown with a solid line. The transition point between the first and second rings <NUM>, <NUM>, is in the example of <FIG> at the commissure denoted <NUM>, whereas the transition point between the first and second rings <NUM>, <NUM>, is in the example of <FIG> at the commissure denoted <NUM>'. <FIG> show examples of an annuloplasty device <NUM> which may be arranged as illustrated in <FIG>.

Further with respect to the examples where the annuloplasty device <NUM> comprises retention units <NUM>, <NUM>', having retention units <NUM>, <NUM>', at both sides of the valve provides for increasing the retention force and the strength by which the annuloplasty device <NUM> is fixated at the valve. The retention units <NUM>, <NUM>', may thus engage the tissue from both of the mentioned sides, creating a strong retention force in the radial direction, i.e. perpendicular to the axial direction <NUM>. The first and second supports <NUM>, <NUM>, pinch the tissue from both sides of the valve, so that the retention units <NUM>, <NUM>', a forced into the tissue. The retention units <NUM>, <NUM>', may provide for shaping the annulus as desired even with a reduced pinching force, since the retention units <NUM>, <NUM>', may provide for fixating the shape of the annulus in the radial direction because of the mentioned retention force. This provides for a more reliable implantation at the heart valve, both in the short term and in the long term.

The first and second retention units <NUM>, <NUM>', may extend in opposite directions along the axial direction <NUM>, as schematically illustrated in e.g. <FIG>. It is conceivable that the first and second retention units <NUM>, <NUM>', may extend with an angle relative the axial direction <NUM>, and further that the aforementioned angle may vary for different retention units <NUM>, <NUM>', along the length of the first and second support rings <NUM>, <NUM>. The angle may vary so that the first and second retention units <NUM>, <NUM>', are extending to securely engage and pierce into the tissue along the length of the first and second support rings <NUM>, <NUM>. The first and second retention units <NUM>, <NUM>', extending away from the first and second support rings <NUM>, <NUM>, should be construed to also encompass variations in the aforementioned angle. The angle in which the retention units extend may vary as further described in the examples below.

In a first state, as mentioned above, the first and second retention units <NUM>, <NUM>', may taper in a direction away from the first and second support rings <NUM>, <NUM>, as illustrated in <FIG>. Thus, when the first and second rings <NUM>, <NUM>, are displaced relative to each other and introduced in the shape seen in <FIG> at opposite sides of the heart valve leaflets, the first and second retention units <NUM>, <NUM>', have inverted positions with the tapered shape directed towards the opposite support ring <NUM>, <NUM>, to engage the tissue pinched between the first and second support rings <NUM>, <NUM> (<FIG>).

The first and second retention units <NUM>, <NUM>', may taper with a cone-shape, as illustrated in the example of <FIG>. This provides for an efficient piercing into the tissue while the amount of cutting is minimized, since the first and second retention units <NUM>, <NUM>', tapers to a point. Tissue damage may thus be minimized while a secure anchoring of the first and second support rings <NUM>, <NUM>, is provided. The first and second retention units <NUM>, <NUM>', may further be shaped as truncated cones, as illustrated in the example of <FIG>.

The retention units <NUM>, <NUM>', may be integrated with the first and/or second support rings <NUM>, <NUM>, as schematically illustrated in e.g. <FIG>, <FIG>, <FIG>. By having retention units <NUM>, <NUM>', integrated with the first and/or second rings <NUM>, <NUM>, a robust, less complex and more readily implementable fixation mechanism can be provided. As illustrated in e.g. <FIG>, a plurality of retention units <NUM>, <NUM>', may be provided on the respective first and second supports <NUM>, <NUM>. Each individual retention unit <NUM>, <NUM>', may engage or pierce into the tissue with a short distance, for a minimum amount of injury to the tissue. The sum of the retention force and friction created from all the retention units <NUM>, <NUM>', may still provide for a strong fixation into the tissue. The scar healing will be quick since each individual retention unit <NUM>, <NUM>', as relatively small dimensions. This provides for a non-traumatic and still secure fixation of the annuloplasty device <NUM>. Hence, the retention units <NUM>, <NUM>', may provide for tissue fixation at multiple points across the annuloplasty device <NUM> resulting in reduced forces per fixation point, and no need for bulky stitching device or knotting device. There is further no risk of coronary artery occlusion or coronary sinus perforation. Hence, the annuloplasty device <NUM> provides for ease of operation, and a less time consuming procedure than stitching.

The first and/or second support rings <NUM>, <NUM>, may be formed from a material with circumferential walls <NUM> enclosing an interior channel <NUM> extending in a longitudinal direction <NUM> of the first and/or second support rings <NUM>, <NUM>. In case the annuloplasty device <NUM> comprises retention units <NUM>, <NUM>', the latter may extend through respective openings <NUM> in the circumferential walls <NUM>, as schematically illustrated in <FIG> and <FIG>, <FIG>. This provides for a robust fixation of the retention units <NUM>, <NUM>', at the first and/or second support rings <NUM>, <NUM>, due to the support provided by the circumferential walls <NUM> at the openings <NUM>.

The first and second retention units <NUM>, <NUM>', may extend through the interior channel <NUM>, as schematically illustrated in <FIG>. This provides for further increasing the robustness and strength of fixation of the first and second retention units <NUM>, <NUM>'. The first and second retention units <NUM>, <NUM>', may be supported by an inner surface <NUM> of the interior channel <NUM>, opposite the openings <NUM>, as schematically illustrated in <FIG>.

The first and second retention units <NUM>, <NUM>', may have respective attachment points <NUM> to the inner surface <NUM> of the interior channel <NUM>, opposite the openings <NUM>. Fixating the first and second retention units <NUM>, <NUM>', to the inner surface <NUM> provides for a particularly robust anchoring. The first and second retention units <NUM>, <NUM>', may be welded to the respective attachment points <NUM>. The circumferential walls <NUM> may have a tubular shape enclosing the interior channel <NUM>. Having the first and second support rings <NUM>, <NUM>, formed form a tubular material may provide for desired compression force against the tissue in some applications. In other examples, the first and/or second support rings <NUM>, <NUM>, may have a cross-section which is non-circular, as schematically illustrated in <FIG>, <FIG>.

In the examples where the annuloplasty device <NUM> comprises retention units <NUM>, <NUM>', the retention units <NUM>, <NUM>', may be formed from the material of the circumferential walls <NUM>. This may provide for particularly robust and strong retention units <NUM>, <NUM>', and an overall robust fixation mechanism for the annuloplasty device <NUM>. The retention units <NUM> may be formed from the material of the first support <NUM>. Similarly, retention units <NUM>' may be formed from the material of the second support <NUM>. The retention units <NUM>, <NUM>', may be cut into shape from the material of the circumferential walls <NUM>. The first and second supports <NUM>, <NUM>, may be integrated and formed from a continuous piece of material. Hence, the retention units <NUM>, <NUM>', may also be formed from such material.

The retention units <NUM>, <NUM>', may be cut to form various shapes for optimizing the gripping force into the tissue. The retention units <NUM>, <NUM>', may be formed by different cutting techniques such as milling or laser cutting techniques. It is also conceivable that the retention units <NUM>, <NUM>', are fixed or integrated onto the respective support rings <NUM>, <NUM>, by other methods, or by being formed from other materials.

The first anterior portion <NUM> may comprises a first plurality 104a of the first retention units <NUM>, and the second anterior portion <NUM>' may comprises a smooth surface free from retention units <NUM>', as schematically illustrated in <FIG>. This provides for a secure anchoring into the tissue with the second anterior portion <NUM> at the atrial side, while at the same time the risk of tissue damage is minimized in the ventricle along the first anterior portion <NUM>.

The first posterior bow <NUM> may comprise a second plurality 104p of the first retention units <NUM>, as schematically illustrated in e.g. <FIG> and in the related cross-section B'-B' in <FIG>. The second plurality 104p of the first retention units <NUM> may taper in a direction extending essentially parallel with the central axis <NUM>. The second plurality 104p of the first retention units <NUM> on the first support ring <NUM> may thus extend substantially straight into the tissue, parallel with the central axis <NUM>, along the posterior leaflet on the atrial side.

The second posterior bow <NUM>' may further comprises a second plurality 104p' of the second retention units <NUM>', as schematically illustrated in e.g. <FIG> and in the related cross-section B'-B' in <FIG>. The second plurality 104p' of the second retention units may taper in a direction extending essentially parallel with the central axis <NUM>. the retention units 104p, 104p', on the first and second posterior bows <NUM>, <NUM>', may be essentially parallel to eachother and to the central axis <NUM>. This provides for a secure fixation to the valve anatomy.

Turning to the example in <FIG> and <FIG>, the first anterior portion <NUM> may comprises a first plurality 104a of the first retention units <NUM>. The first plurality 104a of the first retention units may taper in a first direction 104A forming a first angle (va) with the central axis <NUM>, as schematically illustrated in <FIG> and in the related cross-section A-A in <FIG>. In one example, the annuloplasty device <NUM> in <FIG> is in the aforementioned relaxed first state. as seen in e.g. <FIG> and <FIG>, the retention units 104a, 104a', extend in directions away from eachother, whereas in the displaced second state the first and second support rings <NUM>, <NUM>, will be displaced so that their relative positions are shifted and the retention units 104a, 104a', extends towards eachother. On another example however, as described above, the first and second support rings <NUM>, <NUM>, are not inverted in the relaxed state. Having the first plurality 104a of the first retention units <NUM> extending with an angle (va) relative the central axis <NUM> provides in some applications for an improved anchoring into the tissue at the anterior leaflet on the atrial side.

The first direction 104A may extend at least partly radially inwards towards the central axis <NUM>, i.e. opposite direction (R) as indicated schematically in <FIG>. The first plurality 104a of the first retention units <NUM> may this grip into the tissue with an angle radially inwards, and the risk for dislocation by a force acting radially inwards on the first support ring <NUM> may thus minimized in some procedures.

The first posterior bow <NUM> may comprise a second plurality 104p of the first retention units <NUM>, as schematically illustrated in e.g. <FIG> and in the related cross-section B-B in <FIG>. The second plurality 104p of the first retention units <NUM> may taper in a second direction 104P extending essentially parallel with the central axis <NUM>. The second plurality 104p of the first retention units <NUM> on the first support ring <NUM> may thus extend substantially straight into the tissue, parallel with the central axis <NUM>, along the posterior leaflet on the atrial side. Having a combination of straight retention units 104p on the posterior bow <NUM> and angled retention units 104a on the anterior portion <NUM> provides for an effective yet facilitated anchoring into the tissue in some procedures and anatomies.

The second anterior portion <NUM>' may comprises a first plurality 104a' of the second retention units <NUM>', as schematically illustrated in e.g. <FIG> and in the related cross-section A-A in <FIG>. The first plurality 104a' of the second retention units may taper in a second direction 104A' forming a second angle (va') with the central axis <NUM>. The second direction 104A' may extend at least partly radially outwards towards a radial direction (R), as indicated in <FIG>. The radial direction (R) is perpendicular to the central axis <NUM>. The second support ring <NUM> will in the displaced second state be arranged in the ventricle, thus the first plurality 104a' of the second retention units <NUM>' will extend with the second angle (va') radially outwards into the tissue at the ventricular side along the anterior leaflet. This provides of an efficient anchoring into the aortoseptal wall in some procedures. In one example, having a combination of retention units 104a on the anterior portion <NUM> of the first support ring <NUM> being angled radially inwards and retention units 104a' on the anterior portion <NUM>' of the second support ring <NUM> being angled radially outwards provides for an effective anchoring and retention of the annuloplasty device <NUM> on the opposite sides of the valve <NUM>.

The second posterior bow <NUM>' may further comprises a second plurality 104p' of the second retention units <NUM>', as schematically illustrated in e.g. <FIG> and in the related cross-section B-B in <FIG>. The second plurality 104p' of the second retention units may taper in a second direction 104P' extending essentially parallel with the central axis <NUM>. the retention units 104p, 104p', on the first and second posterior bows <NUM>, <NUM>', may be essentially parallel to eachother and to the central axis <NUM>.

The first and second anterior portions <NUM>, <NUM>', may comprise retention units <NUM>, <NUM>', arranged adjacent the "tricone areas" of the mitral valve, adjacent the commissures <NUM>, <NUM>'. Gripping and fixation into the tissue at these areas provides for a robust and secure anchoring of the annuloplasty device <NUM> to the heart valve. The retention units <NUM>, <NUM>', may be evenly spaced along at least part of the first and/or second anterior portions <NUM>, <NUM>', as exemplified in <FIG> and <FIG>. Such even distribution of the fixation points provides for a reliable anchoring to the tissue, minimizing the risk of localized pressure peaks. It should be understood however that the distance between each of the retention units <NUM>, <NUM>', may be varied to optimize the anchoring annuloplasty device <NUM> to different anatomies. The first and/or second anterior portion <NUM>, <NUM>', may have <NUM> to <NUM> retention units <NUM>, <NUM>', respectively. The first and/or second posterior portion <NUM>, <NUM>', may have <NUM> to <NUM> retention units <NUM>, <NUM>', respectively. This may provide for a particularly efficient fixation to the tissue while minimizing the overall tissue penetration. It should be understood however that the number of retention units <NUM>, <NUM>', may be varied to optimize the anchoring annuloplasty device <NUM> to different anatomies and valves of different size. In one example the length of the retention units <NUM>, <NUM>', is in the range <NUM> - <NUM>. In another example the length of the retention units <NUM>, <NUM>', is in the range <NUM> - <NUM>, such as <NUM>, which may provide for a particularly advantageous fixation into the tissue while being easy to deploy via a delivery catheter.

The advantageous features of the retention units <NUM>, <NUM>', described in relation to <FIG> provides for an improved annuloplasty device <NUM> with a facilitated anchoring into the tissue, also in absence of the aforementioned displacement (d) in the relaxed state. in this case, the annuloplasty device <NUM> has a relaxed state corresponding to the illustration in <FIG>. the retention units <NUM>, <NUM>', points in a direction towards eachother in the relaxed state.

As mentioned, the first support ring <NUM> may comprise a first posterior bow <NUM> and the second support ring comprises a second posterior bow <NUM>'. The first and second posterior bows <NUM>, <NUM>', may be adapted to conform to a posterior aspect of the heart valve. The first and second posterior bows <NUM>, <NUM>', may be separated by an intermediate anterior portion <NUM>. Although the advantages of having retention units <NUM>, <NUM>', on the anterior portions <NUM>, <NUM>', has been described with respect to the examples of <FIG> and <FIG>, it is conceivable that the anterior portion <NUM> may comprise a smooth surface, as described above with respect to the example in 18a. the smooth surface may be free from retention units <NUM>, <NUM>'. A further example is illustrated in <FIG>, showing the rings <NUM>, <NUM>, in a stretched configuration. The retention units <NUM>, <NUM>', may thus be arranged on respective first and second posterior bows <NUM>, <NUM>'. The first and second retention units <NUM>, <NUM>', may be arranged with an off-set distance <NUM> from the anterior portion <NUM> towards respective first and second posterior bows <NUM>, <NUM>'. Thus, the anterior portion <NUM> may comprise a smooth surface free from retention units <NUM>, <NUM>'. the first and second retention units <NUM>, <NUM>', may be arranged with an off-set distance <NUM> from the anterior portion <NUM> towards respective first and second posterior bows <NUM>, <NUM>'. The off-set distance <NUM> may be varied to optimize the annuloplasty device <NUM> to the particular. The first support <NUM> may have the retention units <NUM> extending in a first direction, and the second support <NUM> may have the retention units <NUM>' extending in an opposite direction.

The position of the first retention units <NUM> may be off-set in the radial direction (perpendicular to the axial direction <NUM>) with respect to the second retention units <NUM>'. Thus, although both the first and second retention units <NUM>, <NUM>', may extend in the vertical direction, the risk of having the first retention units <NUM> to engage with the second retention units <NUM>' is avoided, which otherwise may lead to fully penetrating the valve tissue. This may be realized by having different diameters of the support rings <NUM>, <NUM>, and/or by arranging the first and second retention units <NUM>, <NUM>', to extend from opposite sides of the respective support rings <NUM>, <NUM>.

It should be understood that in one example only the first or second support ring <NUM>, <NUM>, may comprise retention units <NUM>, <NUM>'. In a further example, the annuloplasty device <NUM> do not comprise any retention units <NUM>, <NUM>', as illustrated in <FIG>, <FIG>. In the examples of <FIG>, <FIG>, the curvature or position of the first and second support rings <NUM>, <NUM>, may be carefully tailored to the anatomy, due to the transition section <NUM>, to provide a secure position of the annuloplasty device <NUM> also in absence of retention units <NUM>, <NUM>'.

In some examples, the first and/or second support rings <NUM>, <NUM>, may have a cross-section which is non-circular, as schematically illustrated in <FIG>, <FIG>. The first and/or second support rings <NUM>, <NUM>, may be formed from a solid material without an interior channel <NUM>, which may have a non-circular cross-section. 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 of the cross-section may be varied in order to provide for an optimized bending resistance of the support rings <NUM>, <NUM>. The cross-section may be essentially rectangular.

The cross-section may vary along a longitudinal direction <NUM> of the first and/or second support ring <NUM>, <NUM>. Varying the aforementioned dimensions of the sides (e.g. the sides of a rectangle) 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 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, such as the commissure sections <NUM>'b, <NUM>'c, (see e.g. <FIG>) may have a cross-section which increases the flexibility, e.g. by having a reduced area and/or reduced width in the direction in which the support ring <NUM>, <NUM>, is bent.

<FIG>, <FIG> are schematic illustrations of a further example of an annuloplasty device <NUM> comprising a transition section <NUM> providing for the advantageous benefits as described above with respect to <FIG>.

The second anterior portion <NUM>' comprises an inverted section <NUM> extending in parallel with the first and second coil planes <NUM>', <NUM>'. The inverted section <NUM> and the second posterior bow <NUM>' extend on opposite sides of the first support ring <NUM> with respect to the direction of the central axis <NUM>, as schematically illustrated in e.g. the side view of <FIG> and the perspective view of <FIG>. Having a section of the second anterior portion <NUM>' raised above the first support ring <NUM>, i.e. above the first anterior portion <NUM> as illustrated in <FIG>, provides for increasing the compression force along the anterior portions <NUM>, <NUM>', when the first and second support rings <NUM>, <NUM>, are arranged on opposite sides of the heart valve. When the annuloplasty device <NUM> is positioned at the heart valve, with the second support ring <NUM> arranged in the atrial side, the inverted section <NUM> will be pushed down, i.e. against the direction of the central axis <NUM> in <FIG>, when forced into place at the heart valve. The anterior portion <NUM>' will thus also be placed at the atrial side of the heart valve. Having an inverted section <NUM> in the relaxed state of the annuloplasty device <NUM> means that the second anterior portion <NUM>' will strive towards the relaxed shape, free from outside forces, as illustrated in e.g. <FIG>. The inverted section of the second anterior portion <NUM>' will thus strive to a position above the first anterior portion <NUM> (as shown in <FIG>), with respect to the central axis <NUM>. This will cause an increased pressure on the valve tissue along the inverted section <NUM>, and between the first and second anterior portions <NUM>, <NUM>', when the annuloplasty device <NUM> is implanted. This provides for a more secure fixation of the annuloplasty device <NUM> at the heart valve.

The first and second support rings <NUM>, <NUM>, have respective first and second free ends <NUM>, <NUM>', configured to be arranged on opposite sides of the native heart valve leaflets, as described above. In one example, the inverted section <NUM> transitions to the free end <NUM>' of the second support ring <NUM> over an anterior transition section <NUM>, as schematically illustrated in the side view of <FIG> and the perspective view of <FIG>. The anterior transition section <NUM> bends at least partly along the central axis <NUM> so that the free end <NUM>' of the second support ring <NUM> is arranged on the same side of the first support ring <NUM> as the second posterior bow <NUM>', with respect to the direction of the central axis <NUM>. Having the free end <NUM>' recessed from the inverted section, against the direction of the central axis <NUM>, provides for a further improved accommodation to the anatomy of the heart valve. For example, the free end <NUM>' may be positioned to sit in the subannular groove by having such anterior transition section <NUM>. The anterior transition section <NUM> may be arranged at the end of the first and second anterior portions <NUM>, <NUM>', in a direction towards the free end <NUM>', as exemplified in <FIG>. The second support ring <NUM> may comprise a free end <NUM>' which is curved towards the free end <NUM> of the first support ring <NUM>, in the plane of coil planes <NUM>', <NUM>', as further exemplified in <FIG>. The second support ring <NUM> may thus be bent after the second anterior portion <NUM>', i.e. adjacent the position of the commissure. In one example, the anterior transition section <NUM> is arranged towards the end of the second anterior portion <NUM>', in a direction towards the free end <NUM>', so that essentially the entire curved part of the second support ring <NUM>, after the second anterior portion <NUM>', is arranged at the same side of the first support ring <NUM> as the second posterior bow <NUM>' with respect to the direction of the central axis <NUM>. This provides in some examples for an improved fit to the surrounding anatomy of the annuloplasty device <NUM>.

The second anterior portion <NUM>' may comprise a second anterior transition section <NUM>, where the second support ring <NUM> is bent in a direction along the central axis <NUM> to form the step-up curve of the inverted section <NUM>, as exemplified in <FIG>. The step-down curve of the inverted section <NUM>, towards the free end <NUM>', may consequently be formed by the anterior transition section <NUM> described above. The advantageous features of the inverted section <NUM>, and anterior transition sections <NUM>, <NUM>, described in relation to <FIG>, <FIG>, provides for an improved annuloplasty device <NUM> with a stronger retention into the tissue, also in absence of the aforementioned transition section <NUM>. The inverted section <NUM> thus also provides for a separate aspect of the invention.

In the examples of <FIG>, <FIG>, the length of the first and second support rings <NUM>, <NUM>, form essentially two complete loops. This provides in some examples for an improved anchoring of the annuloplasty device <NUM> to the heart valve. In some situations, an off-set distance <NUM> as described in relation to <FIG> may be advantageous.

The second posterior bow <NUM>' may comprise a central posterior arch <NUM>'a, and further a first commissure section <NUM>'b and a second commissure section <NUM>'c on either side of the central posterior arch <NUM>'a, as schematically illustrated in <FIG> and <FIG>. The first support ring <NUM> transitions to the first commissure section <NUM>'b over the transition section <NUM>, and the second commissure section <NUM>'c connects to the second anterior portion <NUM>'. In one example, a separation distance (d<NUM>) between the first support ring <NUM> and the central posterior arch <NUM>'a, along the central axis <NUM>, is less than a separation distance (d<NUM>, d<NUM>) between the first support ring <NUM> and any of the first and second commissure sections <NUM>'b, <NUM>'c. The side view of <FIG> is a schematic illustration showing a reduced distance (d<NUM>) between the first and second support rings <NUM>, <NUM>, compared to the distance (d<NUM>, d<NUM>) along any of the first and second commissure sections <NUM>'b, <NUM>'c. This provides for an improved compression between the first and second support rings <NUM>, <NUM>, along the central posterior arch <NUM>'a. The fixation of the annuloplasty device <NUM> may thus be facilitated. At the same time, the larger separation distance (d<NUM>, d<NUM>) at the first and second commissure sections <NUM>'b, <NUM>'c, can provide for a more reliable fit to the tissue at the commissure anatomy of the heart valve, e.g. as described above with respect to having the separation distance (d<NUM>) at the transition section <NUM>.

In one example, a separation distance (d<NUM>) between the first commissure section <NUM>'b and the first support ring <NUM> is larger than a separation distance d<NUM> between the second commissure section <NUM>'c and the first support ring <NUM>. <FIG> show an example of such increased separation distance (d<NUM>). Hence, as described above with respect to the transition section <NUM>, this provides for an improved fit to the anatomy where the first support ring <NUM> extends through the commissure and transitions to the second support ring <NUM> on the opposite side of the heart valve. In one example the separation distances d<NUM> and d<NUM> may be essentially the same.

The advantageous features of the relation between separation distances (d<NUM>, d<NUM>, d<NUM>) described in relation to <FIG>, provides for an improved annuloplasty device <NUM> with a more secure anchoring into the tissue, also in absence of the aforementioned inverted section <NUM>.

The first and second support rings <NUM>, <NUM>, may have respective free ends <NUM>, <NUM>', as illustrated in <FIG>. The free ends <NUM>, <NUM>', may be configured to be arranged on opposite sides of the native heart valve leaflets. The two free ends <NUM>, <NUM>', may be displaced from each other with a peripheral off-set distance <NUM> extending in a coil plane <NUM>, as schematically illustrated in <FIG>. The coil plane <NUM> is substantially parallel to an annular periphery <NUM> of the coil formed by the first and second support rings <NUM>, <NUM>, and perpendicular to the axial direction <NUM>. The coil plane <NUM> accordingly corresponds to the plane spanned by the annular periphery <NUM> of the device <NUM> when in the coiled configuration. The peripheral off-set distance <NUM> between the two free ends <NUM>, <NUM>', thus extends substantially perpendicular to the central axis <NUM>. This means that, when the device <NUM> is positioned in the implanted state, around the annulus of the heart valve, the two free ends <NUM>, <NUM>', will be separated along the plane of the valve. Having such off-set <NUM> in the plane of the valve, resulting in a reduced length of the first or second support rings <NUM>, <NUM>, may be advantageous in some anatomies where there might be a risk of interference with the valve motion. In the example of <FIG> the off-set <NUM> extends along the anterior portion <NUM>. In another example, such as schematically illustrated in <FIG> and <FIG>, the length of the off-set <NUM> is reduced and instead extending along part of the posterior bow <NUM>. This provides in some applications for an enhanced anchoring strength to the tissue as the tissue is pinched along both anterior portions <NUM>, <NUM>', further in combination with having retention units <NUM>, <NUM>', on at least one of the anterior portions <NUM>, <NUM>'. A compression force between the first and second rings <NUM>, <NUM>, may in this example also be exerted onto the "tricone" areas of the valve, adjacent the commissures <NUM>, <NUM>'. In the example of <FIG> and <FIG>, the total circumference of the first and second rings <NUM>, <NUM>, may be approximately <NUM> degrees. The off-set <NUM> may be removed in some examples, to have a complete <NUM> degrees of the turns of the first and second support rings <NUM>, <NUM>, e.g. as illustrated in examples of <FIG>, <FIG>.

A proximal connector element <NUM> may be fixed to the free end <NUM> of the first support ring <NUM>. The example in <FIG> shows a connector element <NUM> comprising an aperture for interlocking with a delivery catheter. Different types of connector elements may be provided at the free end <NUM>. The distal end <NUM>' of the second support ring <NUM> may be shaped with a blunt tip to reduce the risk of damaging the tissue, see <FIG>.

A method <NUM> of repairing a defective heart valve is disclosed. The method <NUM> is schematically illustrated in <FIG>, in conjunction with <FIG>, and <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 <NUM>, <NUM>, 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 second support rings <NUM>, <NUM>, are positioned so that the first support ring <NUM> transitions to the second support ring <NUM> over a transition section <NUM> positioned at a commissure <NUM>, <NUM>', of the heart valve leaflets. The first and second support rings <NUM>, <NUM>, extend in respective first and second coil planes <NUM>', <NUM>', being essentially perpendicular to the central axis <NUM>. The transition section <NUM> bends at least partly along the central axis <NUM> so that the first coil plane <NUM>' is separated a distance (d<NUM>) from the second coil plane <NUM>' along the central axis <NUM> at the transition section <NUM>. The method <NUM> provides for the advantageous benefits as discussed above in relation to the annuloplasty device <NUM> and <FIG>. The method <NUM> allows for a facilitated anchoring of the annuloplasty device <NUM> at the heart valve, due to the improved accommodation to the surrounding anatomy at the heart valve and increased compression force between the first and second support rings <NUM>, <NUM>, without the need to apply sutures, clips or other external fastening devices.

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 support ring transitions to the second support ring over a transition section (<NUM>), wherein the transition section is adapted to be arranged at a commissure (<NUM>, <NUM>') of the heart valve leaflets,
wherein the first and second support rings extend in respective first and second coil planes (<NUM>', <NUM>') being essentially perpendicular to the central axis, and
wherein the transition section bends at least partly along the central axis so that the first coil plane is separated a distance (d<NUM>) from the second coil plane along the central axis at the transition section,
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, characterized in that
the second anterior portion (<NUM>') comprises an inverted section (<NUM>) extending in parallel with the first and second coil planes, wherein the inverted section and the second posterior bow (<NUM>') extend on opposite sides of the first support ring with respect to the direction of the central axis (<NUM>).