Patent Description:
Biological prostheses are medical devices that use mammalian donor tissues. Examples of suitable mammalian tissues include, for example, bovine, porcine, ovine, equine, and human tissues. Depending on the various medical uses of a biological prosthesis, the donor tissue may include, for example, cardiac valves, pericardium, tendons, ligaments, dura mater, skin, and veins.

Many processes and chemicals employed to treat tissue for a bioprosthesis result in crosslinking of the extracellular collagen matrix within the tissue. Crosslinking or "fixing" of the extracellular matrix improves the strength and biological durability of the tissue. Aldehyde based processes are a typical example of this approach. Aldehyde based processes are also used to provide chemical sterilization to the bioprosthesis. Applied to a decellularized tissue or to a material obtained via tissue engineering, these crosslinking/sterilization methods reduce the ability of the tissue to remodel. In some applications, crosslinking or "fixing" of the extracellular matrix improves the strength and biological durability of the tissue.

As an additional drawback, aldehyde based fixing processes result in a treated implantable material requiring specific storage solutions to preserve the integrity thereof, such as for example, storage in bacteriostatic liquid storage solution. This is commonly referred to as a "wet" implantable material.

Another group of implantable materials include decellularized, fixed mammalian tissue that is sterilized and preserved sterile and dry without impairing the ability of the extracellular matrix to be remodeled, or else implantable materials including decellularized mammalian tissue that has been fixed.

In either case, the decellularized tissue may be made by removing the cells from mammalian tissue, such as a porcine heart valve, leaving behind the extracellular matrix. Other mammalian tissues may include bovine pericardium, equine pericardium or other porcine tissues such as the intestinal mucosa. Alternatively, the tissue may be made by seeding a polymeric mold with mammalian cells which grow along the polymeric mold to produce the extracellular matrix of collagen or of other structural proteins. Once completed, the cells are removed, leaving behind the extracellular matrix.

After decellularization, the decellularized tissue (or polymer with attached extracellular matrix, in alternative embodiments) is treated with a solution in order to reduce the retained water in the tissue. In some embodiments, the treatment solution includes one or more polyols, for example a mixture of glycerol and one or more polyols other than glycerol. In some embodiments, the one or more polyols can include at least one of <NUM>,<NUM> propanediol, <NUM>,<NUM> octanediol, <NUM>,<NUM> butanediol, fructose, xylitol, mannitol, sorbitol, lactulose, lactic acid, maltose, glucose, galactose, erythritol, lactobionic acid or its salts, and hyaluronic acid of various molecular weights and crosslinked to various degrees or not crosslinked.

Implantable materials of these latter types are commonly referred to as "dry" implantable materials. An advantage thereof is the possibility of long-time dry storage with no significant deterioration of the material or the properties thereof. In other words, such implantable materials can be stored without soaking the same into a preservation solution as it happens with the "wet" implantable materials.

Whether "wet" or "dry", the available implantable materials may be used for the manufacturing of cardiovascular prosthesis such as heart valve prostheses or prosthetic conduits. The manufacturing of these prostheses involves the provision of features on a starting implantable material, which generally comes as a sheet material. These features may include for example - without this being an exhaustive list - the perimeter of a functional portion of a prosthetic heart valve such as a valve leaflet, or a leaflet edge, or else a through hole providing a sewing location for assembly of the prosthesis and/or assembly of the prosthesis onto a supporting structure. For a prosthetic vascular conduit, such features may include once again through holes as sewing references or opening a port in a conduit wall for subsequent fitting of a branching portion, such as in vascular prostheses for bifurcated portions of the vasculature.

Under these circumstances, the manufacturing of cardiovascular prostheses (e.g. prosthetic conduits, prosthetic valved conduits, and heart valve prostheses) with the biological implantable materials discussed in the foregoing is generally subject to a tradeoff between dimensional consistency and repeatability of the products, and preservation of the performances of the implantable material.

Processing of the implantable material to provide features thereto may be done via purely mechanical processing (e.g. mechanical cutting) or via optoelectronic processing, including e.g. laser treatment. Both these techniques are affected by certain drawbacks. Mechanical cutting may in some instances require extensive manipulation of the implantable material just to make the interaction with the cutting tools happen. That extensive manipulation may lead to premature degradation of the material, well ahead of any implantation event. Additionally, certain features may hardly - if at all - be provided on the implantable material due to dimensional constraints. For example, the provision of sewing holes or complex contours by way of mechanical processing is generally out of reach as that would weaken the material or damage it to the point of rendering the same unfit for implantation.

<CIT> discloses methods of contouring bioprostheses, in particular cardiac/vascular patches, bioprosthetic heart valves etc. made from e.g. bovine, equine or porcine pericardium, by using a laser, preferably a femtosecond laser.

As to laser processing, this is generally limited to thermal-laser cutting via a CO<NUM> laser. While laser cutting or treatment allows higher precision and can negotiate complex cutting profiles, the main drawback that comes with it - which as a matter of fact limits both the diffusion and the effectiveness of laser treated implantable material - is the interaction of laser beams with water or water-based components embedded in the implantable material. Especially with "wet" implantable materials, which today are the main choice for cardiovascular prostheses due to consolidated storage protocols, thermal power transferred to the implantable material during, e.g., laser cutting, causes sudden, explosive vaporization of water or liquid fractions, thus producing very irregular and/or burnt out cut edges.

When it comes to cutting through holes for, e.g., sewing threads, the above interaction results in holes cut with a largely irregular shape, and with burned out edges all around. Any such hole is completely unsuitable for implantation as it is extremely prone to fail when subject to tension from tightening the stitching threads. Even if those were to resist static load from stitching threads, they would suffer from poor fatigue resistance, thus leading to a major failure of, e.g., a prosthetic valve leaflet when subject to repeated blood pumping cycles.

In a first aspect, the present invention provides a method as defined in claim <NUM>. In a second aspect, the present invention provides an implantable cardiovascular prosthesis as defined in claim <NUM>.

Further features and advantages will become apparent from the following description with reference to the annexed figures, given purely by way of non limiting example, wherein:.

Various embodiments of a method according to the invention are shown herein in relation to the processing of an implantable material to provide a feature thereto. Only embodiments directed to methods employing a CO<NUM> laser treatment and to products obtained by such methods are embodiments according to the claims. According to the disclosure, the term "feature" may identify any geometry feature to be provided onto the starting implantable material to adapt the same to finished product use, such as for example in the manufacturing of cardiovascular prostheses including heart valve prostheses and conduit prostheses.

Geometry features may include both shape geometry defining features such as for example a perimeter or an edge of an element to be cut out of the implantable material, and functional geometry features such as, for instance, through holes to provide sewing locations or else through openings having an elongated shape to receive a stent support post, or - yet further - a surface sculpturing or scoring involving non-through features (e.g. ablated portions having a depth lower than a thickness of the implantable material) which may be used, for instance, to bestow specific deformability patterns to an element of the to-be cardiovascular prosthesis subsequently manufactured using the implantable material treated by the method according to the disclosure.

In embodiments, the features are provided by laser treatment. In embodiments, such laser treatment includes laser cutting. In other embodiments, such laser treatment includes laser ablation to provide non-through features.

Laser treatment according to embodiments is provided as CO<NUM> laser treatment or cutting. According to embodiments not according to the claims, laser treatment may be provided as femtosecond laser treatment or cutting.

When laser treatment to provide features on the implantable material, whether executed by CO<NUM> laser or femtosecond laser, includes laser cutting, the one or more features on the implantable material include laser cutting a line feature.

An example of laser cutting a line feature includes laser cutting a perimeter and/or an edge of an element out of said implantable material. A line feature may be a straight line feature, or a line developing according to a curved profile, a spline, a broken line, etc..

For example, laser cutting line feature may include laser cutting the perimeter of a valve leaflet out of a patch of implantable material or laser cutting an outflow end edge of the same leaflet to achieve a neater profile to reduce blood deposits and/or blood turbulence. Alternatively, laser cutting a line feature may include laser cutting the outline of lumen-type cardiovascular prosthesis such as a prosthetic conduit or a portion thereof.

Laser cutting a line feature may also include laser cutting a closed loop feature. Closed loop features may include, for example, holes or eyelets or generally features leaning more towards the functional side. An example of this includes laser cutting through holes for routing sewing threads of a to-be cardiovascular prosthesis. For example, the method according to embodiments may be used to provide sewing holes for mutual attachment of adjacent leaflets of a bi- or tri-cuspid prosthetic heart valve, and/or for attachment of a valvular sleeve including a plurality of leaflets to a supporting structure or armature including, for instance a perimeter frame or a radially contractible armature such as a stent.

The method disclosed herein involves the use of an implantable material comprising a decellularized sterilized mammalian tissue having an extracellular matrix, wherein a plurality of interstitial spaces of the extracellular matrix include a solution of one or more polyols. In some embodiments, said one or more polyols include at least glycerol. In some embodiments, the solution of one or more polyols includes one or more polyols other than glycerol, and glycerol.

In one embodiment, the glycerol is present in an amount of about <NUM> vol. % to about <NUM> vol. % of the mixture and the one or more polyols other than glycerol are present in an amount of about <NUM> vol. % to about <NUM> vol. % of the mixture.

In another embodiment, the one or more polyols other than glycerol includes at least one of <NUM>,<NUM> propanediol, <NUM>,<NUM> octanediol, <NUM>,<NUM> butanediol, fructose, xylitol, mannitol, sorbitol, lactulose, lactic acid, maltose, glucose, galactose, erythritol, lactobionic acid or its salts, and hyaluronic acid.

In yet another embodiment, the one or more polyols other than glycerol are selected from the group consisting of <NUM>,<NUM> propanediol, <NUM>,<NUM> butanediol, lactobionic acid and its salts, and combinations thereof.

In yet another embodiment, the one or more polyols other than glycerol consists essentially of <NUM>,<NUM> propanediol.

In embodiments, the treatment with the solution includes immersing the tissue in the treatment solution at a temperature ranging from about <NUM> to about <NUM> for a time ranging from about <NUM> hours to about <NUM> hours. In other embodiments, treatment with the solution includes repeated immersions two to three times, each immersion time ranging from about <NUM> hour to about <NUM> hours. In yet other embodiments, the treatment with the solution may include spreading the treatment solution on the tissue or spraying it on the tissue.

In embodiments, during the treatment with the solution, the tissue and the treatment solution can be held under pressure greater than about <NUM> kPa to enhance movement of the treatment solution into the tissue. In embodiments, the pressure under which the tissue and the treatment solution are held during the treatment can range from about <NUM> kPa to about <NUM>,<NUM> kPa. In embodiments, the pressure under which the tissue and the treatment solution are held during the treatment can range from about <NUM> kPa to about <NUM>,<NUM> kPa.

In embodiments, this applying to each and every single embodiment of those mentioned above, the implantable material is dried, to essentially remove aqueous components therein, and sterilized.

The treated tissue may be completely dried by exposing it to air for a time ranging from about <NUM> hours to about <NUM> hours at a temperature ranging from about <NUM> to about <NUM>. In some embodiments, the treated tissue of the implantable material may be dried to remove substantially all of the water, so that the implantable material is substantially free of water. The treatment solution of one or more polyols and, optionally, glycerol, remains within the interstitial spaces of the extracellular matrix, and preserves the integrity and flexibility of the implantable material without the need of storing it in a water based storage solution.

In embodiments, sterilizing the dried tissue may include exposing the dried tissue to ethylene oxide gas, avoiding temperatures above <NUM> in order not to damage the tissue itself. In embodiments, sterilizing the dried tissue may include exposing the dried tissue to ionizing radiation, such as gamma radiation. In embodiments, sterilizing the dried tissue may include exposing the dried tissue to UV light. In some embodiments, the dried tissue may be sterilized by exposure to any combination of ethylene oxide gas, ionizing radiation, and UV light. None of these sterilization methods induces tissue fixation, so remodeling is not impaired.

In embodiments, the implantable material includes bovine glutaraldehyde fixed pericardium. <FIG> attached to the disclosure all feature examples or embodiments involving the use of bovine pericardium. Bovine pericardium may have a thickness comprised between <NUM>,<NUM> and <NUM>,<NUM>.

<FIG> is representative of embodiments of the method wherein the implantable material is decellularized bovine pericardium having an extracellular matrix, wherein plurality of interstitial spaces is filled with <NUM>% wt glycerol + <NUM>% wt <NUM>,<NUM> propandiol and then dried by mechanically removing (e.g. by rolling, using a spreader, using a rolling pin) the excess filler. The bovine pericardium may have a thickness t of <NUM>,<NUM>, and generally comprised between <NUM>,<NUM> and <NUM>,<NUM>. The pericardium is dried and sterilized, and as such it may be identified as "dry" pericardium.

<FIG> is representative of embodiments wherein the feature provided onto the implantable material is a line feature, particularly a linear (straight line) cut. The straight cut is provided by means of a CO<NUM> laser. <FIG> is representative of the same operating conditions, but involves the use of "wet" bovine pericardium as implantable material, according to the prior art. The "wet" implantable material of <FIG> is identified by reference IW, while the "dry" implantable material of <FIG> is identified by the reference "ID". Accordingly, the linear cut is identified by references LCW for the "wet" material and "LCD" for the "dry" material.

The CO<NUM> laser used with the embodiment of <FIG>, and the example of <FIG>, has a wavelength of <NUM>, wherein the wavelength may in general be comprised between <NUM> and <NUM>, a maximum rated power of <NUM> W, wherein maximum rated power may in general be comprised between <NUM> and <NUM> W, a maximum rated processing velocity of <NUM>/s, wherein the maximum rated processing velocity may in general be comprised between <NUM>/s and <NUM>/s, and a lens focal length of <NUM>,<NUM>, wherein the lens focal length may in general be comprised between <NUM> and <NUM>.

Operating parameters applying to the embodiment of <FIG> correspond to the following.

As visible in <FIG> when compared to <FIG>, the surface exposed following cutting exhibits markedly more regular structure, pattern and layout than those exhibited by the exposed surface of <FIG> provides experimental evidence of the circumstances put forward in the introductory portion of this disclosure relating to prior art methods and techniques involving the use of "wet" pericardium as implantable material. Thermal power from laser beams is transferred to the areas surrounding the cutting front, with little heat transfer to neighboring areas due to the generally low thermal conductivity of biological materials. Accordingly, heat is dissipated primarily at the areas surrounding the cutting front, which feature a high liquid concentration due to the water or - generally - the aqueous compounds that soak the interstitial space of the extracellular matrix of the decellularized pericardium. As heat transfers to water or aqueous compounds at the cutting front, the same experience a sudden vaporization featuring extremely high vaporization rates. In other words, the water or aqueous compounds exhibits a quasi-explosive behavior when the implantable material is being impinged upon and cut by the laser beams.

Quasi-explosive vaporization brings about two undesired effects, namely:.

No such effects are observed in <FIG>: the thickness t remains substantially uniform across the length of the linear cut LCW, which may be regarded as bearing witness to the substantial absence of defects under item a) above, and the same thickness t shows no signs whatsoever of burnouts or the like. This is due to the filling of the extracellular matrix with glycerol. Glycerol is around <NUM>% more dense than water, and at room temperature it is more viscous as well. When the "dry" implantable material ID is impinged upon by laser beams for providing the linear cut LCD, the heat flow towards the biological tissue is absorbed almost entirely by glycerol. Being it more dense and viscous than water, and specifically more viscous, sudden and violent vaporization phenomena are substantially ruled out: glycerol provides a thermal sink that absorbs the local thermal shock generated by laser cutting process.

Accordingly, the features of the processed element or component are not significantly different - if at all - from those of the starting material, and fatigue performances are not affected either.

<FIG> are representative of embodiments wherein the feature provided onto the implantable material is a closed loop feature, particularly the cutting of a through hole to provide a sewing reference. The through hole is cut by means of a CO<NUM> laser.

<FIG> are representative of the same operating conditions, but - similar to <FIG> - they involve the use of "wet" bovine pericardium as implantable material, according to the prior art. The "wet" implantable material of <FIG> is again identified by reference IW, while the "dry" implantable material of <FIG> is again identified by the reference "ID". Accordingly, the through holes are identified by references HW for the "wet" material and "HD" for the "dry" material. Figure pairs <NUM>, <NUM> and <NUM>, <NUM> show flip sides of the same implantable material sample wherein the through holes HW and HD respectively have been provided.

Accordingly, whether made on a wet or dry material, the holes appearing in the figures are also identified based on the visible rim being the inlet end or the outlet end of the laser beam. Inlet ends are identified by reference HW_IN for the "wet" material, and by reference HD_IN for the "dry" material. Consistently, outlet ends are identified by reference HW_OUT for the "wet" material, and by reference HD_OUT for the "dry" material.

The CO<NUM> laser used with the embodiment of <FIG>, and the example of <FIG>, is the same as that used with the linear cuts LCW and LCD of <FIG>, i.e. it has a wavelength of <NUM>, wherein the wavelength may in general be comprised between <NUM> and <NUM>, a maximum rated power of <NUM> W, wherein maximum rated power may in general be comprised between <NUM> and <NUM> W, a maximum rated processing velocity of <NUM>/s, wherein the maximum rated processing velocity may in general be comprised between <NUM>/s and <NUM>/s, and a lens focal length of <NUM>,<NUM>, wherein the lens focal length may in general be comprised between <NUM> and <NUM>.

Operating parameters applying to the embodiment of <FIG> (as well as to the example of <FIG>) are however different from those used on the implantable materials IW and ID of <FIG>, and are chosen with a view of the specific feature being provided, i.e. a through hole.

This being said, the parameters correspond to the following.

As witnessed by the number of passes, in embodiments the through hole may be cut by focusing a laser beam on a spot/an area on the implantable material at the location where the theoretical axis of the hole is intended to be positioned.

Additionally, with reference to the operational ranges posted above, the implantable material patches shown in <FIG>, are processed according to the upper bands of each range.

With reference to <FIG>, the drawbacks from using a " wet" implantable material are amplified when cutting closed loop geometries, especially a through hole. With closed loop geometries, the heat flow remains confined around the focus spot/area and around the hole. This has two immediate consequences, namely:.

Both the burnout ring-shaped areas and the cutouts CO result in a marked deterioration of static resistance (such as, for example, resistance to tearing when sewing threads are tightened to connect portions of a prosthesis together), as well as fatigue resistance.

Conversely, in the embodiments of <FIG> all of the above effects are mitigated or eliminated. As to the inlet ends of the holes HW, there are no visible burnouts B around the perimeter of the holes, while at the outlet ends (<FIG>) the contour of each hole is overall more regular as compared to <FIG>, with no cutouts or distortions observed.

As already discussed with reference to <FIG>, as glycerol is around <NUM>% more dense than water, and at room temperature it is more viscous as well, when the "dry" implantable material ID is impinged upon by laser beams for providing the through holes HD, the share of the heat flow that is absorbed by glycerol is higher as compared to what happens with "wet" materials, and violent vaporization phenomena are substantially ruled out: glycerol provides a thermal sink that absorbs the local thermal shock generated by laser cutting process.

In this case, the effect of glycerol is even more apparent due to the limited size of the area involved. That is, the area of a through hole is so small as compared with that of a linear cut LCD, that the glycerol taking up heat flow from the laser is in an amount proportional to the very area. The thermal sink effect at the laser focusing spot or area is thus limited by the dimensions, but yet it avoids distortions at the hole end edge. Then, the glycerol filling the extracellular matrix at the surrounding areas to the hole(s) proves very effective in countering and avoiding prolonged burnouts and any cutout resulting therefrom.

The features of the processed element or component are thus not significantly different - if at all - from those of the starting material, and fatigue performances are not affected either. This is particularly important as through holes HD may be intended as sewing locations for routing of sewing threads: they must not tear up when stitching the components of the prosthesis together, nor do they have to break open under repeated loads from blood cycle operation.

Confirmation of the performances of the method according to embodiments also come from the subsequent <FIG>, <FIG>, <FIG> as compared to the counterpart "wet" material <FIG>, <FIG>, <FIG>. These figures refer to the same CO<NUM> laser treatment, but the operating parameters are set at intermediate values along the respective ranges. The views being magnified compared to those of <FIG> offer a greater level of detail that allows an even better appreciation of the effects of the method according to the embodiments. All the figures applying to comparative examples on "wet" implantable material show evidence of irregular contours, or even portions of tissues bridging together opposite surfaces of the through hole as a result of an incomplete burnout (<FIG>). Thermal effects are only partly mitigated by the laser being operated at lower power.

No thermal effects are observed in the embodiments of <FIG>, <FIG>, <FIG>: the holes HD exhibit a largely more regular shape overall, with substantially no burnout areas.

<FIG> is representative of embodiments wherein the feature provided onto the implantable material is, similar to <FIG>, a line feature, particularly a linear (straight line) cut. In these embodiments not according to the scope of the claims, however, the straight cut is provided by means of a femtosecond laser. <FIG> is representative of the same operating conditions, but involves the use of "wet" bovine pericardium as implantable material, according to the prior art already referred to in respect of <FIG>.

The "wet" implantable material of <FIG> is, consistently with the foregoing description, identified by reference IW, while the "dry" implantable material of <FIG> is identified by the reference "ID". Accordingly, the linear cut is again identified by references LCW for the "wet" material and "LCD" for the "dry" material.

The femtosecond laser used with the embodiment of <FIG>, and the example of <FIG>, has a pulse duration of <NUM> femtoseconds (fs) or less, a wavelength of <NUM>, wherein wavelength may in general comprised between <NUM> and <NUM>, and a lens focal length of <NUM>, wherein lens focal length may in general be comprised between <NUM> and <NUM> mm.

A femtosecond laser interacts with the implantable material in a way closer to mechanical ablation than thermal ablation. A femtosecond laser may be used, in embodiments, to provide non-through features of the types listed in the foregoing description. This substantially eliminates thermal defects such as burnouts or cutouts, and the distortions from quickly evaporating water, but still geometry problems remain when "wet" materials are used.

As visible in <FIG> when compared to <FIG>, the surface exposed following cutting exhibits an essentially pristine structure, as if it was cut by a mechanical tool. All of the pericardium layers are perfectly visible across the thickness t, and overall there is no alteration whatsoever to the cutout component as compared to the starting material.

As to the comparative example of <FIG>, the cut profile shows evidence of geometric singularities such as bulges BL and dents D, and the layers are less visible - if at all - than <FIG>.

The advantage may not reside in thermal sink properties of glycerol, but rather on the structural coherence the same provides to the "dry" implantable material ID. To provide a comparison, when interacting with a femtosecond laser, the "wet" material IW has an extracellular matrix that may be regarded as a dry sponge. Water or aqueous compounds in general do not fill the extracellular matrix as water would do with an actual soaked sponge, nor would water or aqueous compounds provide any additional structural contribution to the extracellular matrix due to the comparably low density and viscosity thereof.

With a glycerol treated implantable material ID, glycerol - having its higher density and viscosity - fills the interstitial space in the extracellular matrix and renders the extracellular matrix a very cohesive and solid structure, much different from the fundamentally alveolar and relatively "fragile" structure of the "wet" material.

<FIG> is representative of embodiments wherein the feature provided onto the implantable material is a closed loop feature, particularly the cutting of a through hole to provide a sewing reference. The through hole is cut by means of the femtosecond laser.

<FIG> is representative of the same operating conditions, but - similar to <FIG>, <FIG>, <FIG>, <FIG>, <FIG> - they involve the use of "wet" bovine pericardium as implantable material, according to the prior art. The "wet" implantable material of <FIG> is again identified by reference IW, while the "dry" implantable material of <FIG>, is again identified by the reference "ID".

Accordingly, the through holes are identified by references HW for the "wet" material and "HD" for the "dry" material. Whether made on a wet or dry material, the holes appearing in the figures are also identified based on the visible rim being the inlet end or the outlet end of the laser beam, which in this case is the sole inlet end. Consistently with the above, inlet ends are identified by reference HW_IN for the "wet" material, and by reference HD_IN for the "dry" material.

The femtosecond laser used with the embodiment of <FIG>, and the example of <FIG> is the same as that used with the linear cuts LCW and LCD of <FIG>, i.e. has a pulse duration of <NUM> femtoseconds (fs) or less, a wavelength of <NUM>, wherein wavelength may in general comprised between <NUM> and <NUM>, and a lens focal length of <NUM>, wherein lens focal length may in general be comprised between <NUM> and <NUM>.

With reference to <FIG>, although the defects on the through hole HW are less extensive than with CO<NUM> laser cut, the outline at the inlet end still exhibits a bulge BL. No such defects are visible on the through hole HD of <FIG>, essentially for the very reasons as discussed in respect of the linear cut. At least roughly, the difference in the interaction with femtosecond laser between "wet" materials and "dry" materials is the same difference with cutting a crispy bread loaf ("wet") and a butter slab ("dry"). While they both get cut acceptably, the butter allows for a smoother cut on account of the much more cohesive structure thereof.

The application of the method according to the embodiments to the manufacture of cardiovascular prostheses may allow, almost single handedly, to overcome all of the drawbacks and technical difficulties encountered with the prior art. Components for heart valve prostheses may be cut out of "dry" implantable material patches, whatever the contour thereof, by means of laser cutting, and may at the same time be provided with stitching references in the form of through holes, all of this with almost untouched mechanical properties compared to the starting material.

Not only this, when comparing components for heart valve prostheses and heart valve prostheses made according to the method of the embodiments with components and prostheses made in accordance with the prior art the difference is staggering. Especially as far as stitching is concerned, stitching patterns get overall more regular and repeatable thanks to the method of the embodiments, and the workers assembling the prosthesis are no longer burdened by the task of piercing the implantable material themselves with a stitching needle. Piercing by a needle inherently creates irregularly shaped holes and slits that in any case have worse fatigue performances than a through hole which is laser cut as a feature into an implantable material.

In summary, prostheses manufactured according to the method of the embodiments have better mechanical strength (both static and fatigue), can be dry stored for long periods of time, and when implanted take benefit from a much extended service life on account of better mechanical properties, all to a higher safety for the patient.

The disclosure that follows includes embodiments of cardiovascular prostheses featuring one or more elements or components made in accordance with the method disclosed herein. An exemplary such prosthesis is disclosed in <CIT> in the name of the same Applicant, and another such prosthesis is disclosed in PCT application no. <CIT> in the name of the same Applicant, and summarized in the brief description below.

With reference to <FIG>, reference number <NUM> designates as a whole a cardiac valve prosthesis according to various embodiments of the disclosure. The description that follows discloses i. a method of making the cardiac valve prosthesis (or other implantable vascular prostheses) by taking advantage of the method of providing features on an implantable material according to embodiments. The implantable vascular prostheses, particularly the cardiac valve prostheses of the embodiments may also be provided within kit including a delivery instrument for the prosthesis and a dry-storage container. Owing to the features of the material ID, storage in a preservation solution is not required. A storage container for embodiments of the kit is disclosed in PCT application no. <CIT>/<CIT> in the name of the same Applicant. A delivery system for embodiments of the kit is disclosed in PCT application no. <CIT> in the name of the same Applicant. The kit may also include a loading facility such as that disclosed in PCT application no. <CIT> in the name of the same Applicant. In embodiments of the kit. The loading facility may be used to facilitate loading of the prosthesis <NUM> onto a delivery instrument.

The cardiac valve prosthesis <NUM> includes an armature <NUM> for anchorage of the valve prosthesis at an implantation site. The armature <NUM> defines a lumen for the passage of the blood flow and has a longitudinal axis X1.

The prosthesis <NUM> also includes a set of prosthetic valve leaflets <NUM> supported by the armature <NUM> and configured to move, under the action of blood flow (which has a main flow direction roughly corresponding to that of the axis X1): in a radially divaricated condition to enable the flow of blood through the lumen in a first direction, and in a radially contracted condition, in which the valve leaflets <NUM> co-operate with one another and block the flow of blood through the prosthesis <NUM> in the direction opposite the first direction. This is commonly referred to as leaflet coaptation.

With reference to <FIG>, in embodiments the armature <NUM> includes an annular part <NUM>, and a pattern of arched struts <NUM> carried by the annular part <NUM>. The annular part has a structure which can expand from a radially contracted condition, associated to delivery of the prosthesis to implantation site, to a radially expanded condition wherein the prosthesis is withheld at the implantation site. In these embodiments, the annular part may have a mesh structure including an annular pattern of multiple strut clusters (cells) having polygonal shape (hexagonal, rhomboidal, etc.).

In embodiments, the features of the valve leaflets <NUM> are provided by the method according to embodiments of this disclosure. As regards the construction of the set of leaflets <NUM> (also referred to as or valve sleeve), in embodiments the prosthetic valve is made with three separate leaflets. Each leaflet is obtained from one sheet of pericardium trimmed accordingly to <FIG>, i.e., according to a substantially lobe-shaped figure. Each trimmed leaflet features two patterns of sewing holes SH and two side wings SW.

In embodiments, each leaflet is provided by the method disclosed herein starting from a sheet of dry pericardium according to the embodiments disclosed in the foregoing. The perimeter PM of each leaflet is exemplary of a line (and through) feature according to the method herein cut through the dry pericardium by means of a CO<NUM> laser or a femtosecond laser, thereby obtaining a cut perimetral edge having the features shown in <FIG> (CO<NUM> laser) and <NUM> (femtosecond laser). Cutting parameters according to the embodiments disclosed herein may be used. Through laser cut may also extend into the perimeter edge as much as needed in order to provide the side wings SW.

The patterns of sewing holes SH are provided as an example of a closed loop (and through) feature according to the method herein, and are cut according to the same method with a final shape exemplified by <FIG>, <FIG>, <FIG>, <FIG> (CO<NUM> laser) or <NUM> (femtosecond laser).

The sewing holes SH are then sewn together forming a sewn stiffer fold which follows the leaflet profile at the root thereof, thereby forming the cusp.

The two side wings SW enable connection of the valve to supporting posts in the valve armature. The sewn fold has the purpose to bias the cusp inwardly thereby encouraging leaflet coaptation, and to avoid contact between the armature <NUM> and the valve leaflets <NUM> avoiding the risk of abrasion due to repeated impact against the armature <NUM>, which, in some embodiments, is a metal material.

The two patterns of holes SH may be sewn together using a suture thread coated with a film of biocompatible material or PET thread or PTFE filament.

This may include in embodiments using the sewing holes SH to sew together the leaflet <NUM> into a valvular sleeve prior to sewing the valvular sleeve to the armature <NUM>.

The sewing pattern may be varied to accommodate the directional differences in the forces exerted at each point of the stitches, prevent the stitches from triggering fatigue fracture lines.

Preferably the stitching follows the pattern identified by letter "C" in Figure 1C (alternate inner and outer surface stitches). The three leaflets <NUM> are then joined at the side wings SW and stitched together along the leaflet post line, i.e., at the interface of adjacent side wings SW, thereby forming a conical duct.

The side wings SW, which allow a slack of material that protrudes outwardly of the duct, are then fixed to the armature posts, which are fully wrapped by the side wings SW.

The extra tissue skirt below the stitching holes SH allows leaflet fixation to the inflow ring <NUM> of the stent, by mean of a stitching line. Additionally, in some embodiments one - preferably the lower one or both of the patterns SH may be stitched to the armature at the annular part <NUM>.

A strip of pericardium is finally stitched to the inflow ring <NUM> outwardly of the same, defining the sealing cuff SC. The strip can be folded on its outflow end to provide a sealing collar along the valve perimeter, or a second strip can be connected by means of a circumferential stitching line to the first strip, to realize a sealing circumferential collar.

Similarly to the leaflets <NUM>, the strip of pericardium defining the inflow ring <NUM> may itself be cut out of a dry sheet of pericardium according to embodiments herein. The perimeter of the strip is another example of a line (and through) feature that may be cut by the method.

As mentioned, the method disclosed herein also allows to provide non-through features on dry pericardium sheets, for example surface sculpturing features or ablation of a part of a layer overall of biological material from the dry pericardium sheet ID, for example to provide differentiated local thicknesses to the pericardium sheet ID to address specific needs.

An exemplary embodiment of a surface sculpturing provided by the method according to embodiments herein is shown in <FIG>. In such embodiments, the surface sculpturing may include one or more sculpturing patterns provided as a sequence of modular sculpturing units. In embodiments, a first sculpturing pattern is provided as an arched contour pattern CP extending along the perimeter of the leaflets <NUM> and intended to increase fatigue resistance of the leaflets <NUM> during coaptation. In embodiments, the contour pattern CP is provided as a result of selective ablation of layer(s) of the leaflet within a perimeter line defined by the contour pattern CP, so that the latter is overall thicker than the leaflet area enclosed thereby. Due to the shape of the contour pattern, increased thickness is crucially located at a fluidodinamically distal edge (outflow end) of the leaflets and at a fluidodinamically proximal edge (inflow end) of the leaflets, viz. the arched "root" of the leaflets, which happen to be the portions most subject to fatigue stress. The terms "fluidodynamically proximal" and "fluidodynamically distal" as used herein refer to the free flow direction of the blood through the prosthesis, a direction that is bottom up as viewed in the figures of the annexed plate of drawings.

In embodiments, a second sculpturing pattern includes pairs of deformation patterns DP. The deformation patterns DP help create preferential folding directions on each leaflet <NUM> to prevent decay in leaflet performances over time, viz. to prevent "freezing" of the shape of the leaflet at locations away from a fluidodinamically distal edge, i.e. at locations near a fluidodinamically proximal edge. Again, the deformation pattern results, in embodiments, from ablation of surrounding portions of dry pericardium sheet ID so that the deformation patterns DP overall edge out of the surrounding areas.

The deformation patterns DP encourage folding deformation of the valve leaflets <NUM> during coaptation, that is, the surrounding portions of the leaflet will be encouraged to fold about - as much as allowed by the overall arrangement of the three leaflets - the thicker deformation patterns DP to maintain a maximum of the leaflet area in active conditions throughout the service life of the prosthesis.

Depending on the needs, each sculpturing pattern CP, DP (including ablation patterns) may be provided either edging out of surrounding areas as disclosed above, or else embossed relative thereto (as a channel-like feature). In this regard, <FIG> is representative of embossed sculpturing patterns CP, DP, while <FIG> is representative of edging out sculpturing patterns CP, DP.

In embodiments, the embossed sculpturing patterns CP, DP of <FIG> are provided as a sequence of circles or closed shape figures chained or cascaded together to provide a continuous overall outline. In the embodiment in the figures, the sculpturing includes sequences of chained or cascaded circles engraved in the pericardium sheet ID by the method according to the embodiments herein. <FIG> is representative of sculptured (non-through) features provided as a sequence of circles chained together and sculptured into the pericardium layer ID by femtosecond laser treatment, while the femtosecond laser treatment provides the ablation of the pericardium in areas surrounding the patterns CP, DP in <FIG>.

The femtosecond laser used with the embodiments of <FIG> may be the same as disclosed in the foregoing, i.e. it has a pulse duration of <NUM> femtoseconds (fs) or less, a wavelength of <NUM>, wherein wavelength may in general comprised between <NUM> and <NUM>, and a lens focal length of <NUM>, wherein lens focal length may in general be comprised between <NUM> and <NUM>.

Operating parameters applying to the embodiments of <FIG> correspond to the following.

The provision of sculpturing patterns CP, DP as embossed features may be desirable, for example, whenever certain elements (say, the leaflets <NUM>) of a cardiovascular prosthesis are to be made out of a relatively thick or thicker than standard pericardium. In that case, fatigue resistance may not be an issue considering that the leaflet would be, so to say, beefed up as compared to a standard manufacturing, but leaflet functionality may be hampered by the extra thickness. For this reason, and with reference to <FIG>, the patterns CP, DP may be provided either at the exact locations as the edging out counterparts in <FIG> or at different locations with the aim of increasing deformability and/or flexural performances of the leaflet. In the embodiment of <FIG>, the provision of embossed patterns as the leaflet contour - pattern CP - and as deformation patterns - pattern DP - within the leaflet contour may ensure that the leaflet does not exhibit excessive stiffness at the relevant locations, thereby compromising the very leaflet coaptation properties.

Another reason to provide embodiments with embossed patterns (e.g. deformation pasterns DP) is that of sculpturing preferential folding or collapse lines to facilitate crimping, whether or not the pericardium is of standard thickness or high thickness.

More in general, surface sculpturing features provided by the method according to embodiments herein may be used to vary the local thickness of the leaflet and/or the local pattern of the leaflet surface to provide the leaflet with desired properties at a specific location. The surface sculpturing patterns CP and DP are one possible example of this.

<FIG> and <FIG> are representative of a CO<NUM> laser sculpturing (ablation) on a section of a valve leaflet <NUM> made of dry pericardium ID, again to provide a contour pattern CP. <FIG> shows the rehydrated dry pericardium sheet. Compared to the same pattern provided by means of CO<NUM> laser on a wet pericardium sheet IW in <FIG> and <FIG>, the sculptured dry pericardium sheet exhibits unprecedented neat sculptured contours.

The CO<NUM> laser used with the embodiment of <FIG>, <FIG>, and the example of <FIG>, <FIG>, is the same as that used with the linear cuts LCW and LCD of <FIG>, i.e. it has a wavelength of <NUM>, wherein the wavelength may in general be comprised between <NUM> and <NUM>, a maximum rated power of <NUM> W, wherein maximum rated power may in general be comprised between <NUM> and <NUM> W, a maximum rated processing velocity of <NUM>/s, wherein the maximum rated processing velocity may in general be comprised between <NUM>/s and <NUM>/s, and a lens focal length of <NUM>,<NUM>, wherein the lens focal length may in general be comprised between <NUM> and <NUM>.

Operating parameters applying to the embodiment of <FIG>, <FIG> (as well as to the example of <FIG>, <FIG>) are however different due to the specific features and requirements of a surface sculpturing (non-through feature).

The prosthetic leaflets <NUM> may be in any number compatible with operation as replacement heart valve. In some embodiments, the set includes a pair of leaflets. In some embodiments, such as that shown in the figures, the set includes three prosthetic valve leaflets <NUM> (e.g. for an aortic valve prosthesis). In some embodiments, the set may include four leaflets <NUM>.

Each valve leaflet <NUM> includes a fluidodynamically proximal edge 4P with an arched pattern, which extends from a base portion at the upper pattern SH and along two adjacent pleat formations PF, and a fluidodynamically distal edge 4D which extends towards the central orifice of the prosthesis <NUM> so as to be able to co-operate with the homologous edges of the other valve leaflets <NUM>.

During operation (heart cycle) the valve leaflets <NUM> experience deformation, divaricating and moving up towards the armature <NUM> so as to enable free flow of the blood through the prosthesis.

When the pressure gradient, and hence the direction of flow, of the blood through the prosthesis tends to be reversed, the valve leaflets <NUM> then move into the position represented in Figure 1A, in which they prevent the back flow of the blood through the prosthesis.

The pattern of arched struts <NUM> includes proximal ends <NUM> connected to the annular part <NUM>, and distal ends <NUM> spaced axially from the proximal ends <NUM> and arranged at an end of the armature <NUM> opposite the annular part <NUM>. In embodiments, the distal ends <NUM> coincide with distal ends of the armature <NUM>, and in embodiments where the distal end of the armature <NUM> coincides with a distal end of the prosthesis <NUM> as a whole, the distal ends <NUM> coincide with a distal end of the prosthesis as well (this is the case of at least some of the embodiments depicted in the figures).

Owing to this layout, in embodiments, the prosthesis <NUM> includes an inflow portion IF essentially corresponding to the annular part <NUM> (whether or not covered by the sealing cuff SC), and an outflow portion OF corresponding essentially to the distal region of the armature, i.e. that where the distal ends <NUM> are arranged.

The armature <NUM> further includes a plurality of sets <NUM> of anchoring formations <NUM> configured to protrude radially outwardly of the annular part <NUM>, each set <NUM> being supported by at least one of the annular part <NUM> and a corresponding arched strut <NUM>, and a plurality of support posts <NUM>, each supported by adjacent arched struts <NUM>, wherein the sets <NUM> of anchoring formations <NUM> alternate with the support posts <NUM> around the longitudinal axis X1. In embodiments the support posts <NUM> are advantageously cantilevered to adjacent arched struts <NUM> and are configured as fixing locations for the prosthetic valve, specifically for the pleat formations PF at the commissural points of the valve.

In this regard, the posts <NUM> are wrapped by adjacent side wings SW previously stitched together during assembly of the prosthetic valve. The leaflets <NUM> may in embodiments be sewn together and to the support posts <NUM> in a single motion, while in other embodiments the leaflets <NUM> are first sewn together to form the valvular sleeve, then the valvular sleeve is sewn to the supporting posts.

Referring again to <FIG>, in embodiments each arched strut <NUM> extends from a first proximal end <NUM>, to a distal end <NUM>, then to a second proximal end <NUM> in a valley-peak-valley sequence, wherein valleys are located at the proximal ends <NUM>, and peaks are located at the distal ends <NUM>. In embodiments the pattern of arched struts includes three adjacent and preferably identical arched struts <NUM> (such as in the figures). With reference to <FIG> and <FIG>, in embodiments, the arched struts <NUM> extend within the boundaries of the inner and outer surfaces of the armature <NUM>, so as to be substantially free of any protrusion relative to those surfaces. In other embodiments the arched struts may have an offset from the inner and outer surfaces of the armature <NUM>, meaning by this they may either protrude radially inwardly or radially outwardly of two cylinder surfaces tangent to the inner and outer surfaces of the armature <NUM> (in the view of <FIG>, this would correspond to a radially inward or a radially outward offset from the circular perimeter of the lumen defined by the armature <NUM>.

In embodiments, the arched struts are sized and dimensioned so as to have a variable curvature between a proximal end <NUM> and a distal end <NUM>, for example with the arched shape starting with a <NUM> degrees tangent at the proximal end <NUM>, and ending up with an <NUM> degrees tangent at the distal end, the angle being measured relative to a direction parallel to the axis X1.

In some embodiments, the arched struts <NUM> are sized and dimensioned so as to exhibit appreciable variations in curvature between proximal and distal ends <NUM>, <NUM>. The pattern of arched struts <NUM> includes distal portions <NUM> located at the distal ends <NUM>, and inter-strut portions <NUM> located at the proximal ends <NUM>. The distal portions <NUM> may be shaped so as to provide a marked local variation in the shape of the strut, for example by exhibiting a C-shape as shown in the figures. The distal portions <NUM> may provide coupling locations for other devices such as a valve holder or a hub of a carrier portion of a delivery catheter. In other embodiments, the distal portions <NUM> may be provided as closed-loop structures such as eyes or eyelets. Note also that closed loop structures may be provided at the annular part <NUM> (either as part of the armature <NUM> or on the sealing cuff SC, for example as loops made of yarn and weaved through the cuff SC) as coupling elements intended to be engaged e.g. by valve loading or crimping facilities or instruments.

In embodiments, the inter-strut portions <NUM> are essentially V-shaped and are defined by the roots of the adjacent arched struts departing from the same proximal end <NUM>. In some embodiments, the inter strut portions <NUM> may exhibit a Y-shape or a U-shape. An example of a Y-shape is shown in the figures (particularly <FIG>) wherein each inter-strut portion <NUM> extends through the mesh of the annular part <NUM>. In these embodiments, the mesh of the annular part <NUM> is provided as a sequence of rhomboidal strut clusters (cells) sequentially connected to each other at endpoints of a diagonal line (such as the shortest diagonal) and exhibiting accordingly an identical circular pattern of free ends on opposite sides of a circumference extending through the sequence of the connection points. The Y-shaped inter-strut portion <NUM> is thus integrally formed at a selected connection point between two adjacent rhomboidal strut clusters, and may extend no further than the proximal end of the armature <NUM>.

In embodiments the strut clusters may be arranged according to an arrow shape, i.e. defined by two axially staggered sinusoidal patterns, circumferentially in phase, bridged by longitudinal struts.

In embodiments, the support posts <NUM> are angularly arranged at an inter-strut location, i.e., a circumferential location arranged at an area where an inter-strut portion <NUM> (as well as - accordingly - a proximal end <NUM> shared by two adjacent arched struts <NUM>) is provided. The support posts may be provided as cantilevered to both the adjacent arched struts <NUM> intervening at an inter-strut portion <NUM> via a first and a second cantilever struts <NUM>, <NUM>, each connected to a corresponding one of said adjacent arched struts <NUM> as shown in the figures. In some embodiments, each cantilever strut <NUM>, <NUM> may be a twin strut.

The cantilever struts <NUM>, <NUM> merge into each corresponding post <NUM> starting from locations on respective arched strut <NUM> approximately halfway through the portion of the arched strut <NUM> extending from a proximal end <NUM> to a distal end <NUM>. Note that in other embodiments the support posts <NUM> may be cantilevered to the annular part <NUM>, for example by being formed integrally with the inter-strut portion <NUM> (which in this case will exhibit a trident shape).

The connection points at which the Y-shaped inter-strut portion <NUM> is formed may be chosen so that the same portions are evenly spaced (angular-wise) around the axis X1. The same applies to the support posts <NUM>, which may be arranged so as to be evenly spaced (angular-wise) around the axis X1.

In some embodiments shown in the figures, the armature <NUM> comprises three arched struts <NUM>, three posts <NUM> spaced <NUM>° around the axis X1, and three sets <NUM>, so that the sequence around the axis X1 is post <NUM> - set <NUM> - post <NUM> - set <NUM> - post <NUM> - set <NUM> (in this sense, even the struts <NUM> and the sets <NUM> do follow a 120degree-like distribution). In embodiments the three sets <NUM> include each a pair of anchoring formations <NUM>, wherein each set <NUM> (and accordingly each anchoring formation <NUM>) extends bridge-wise between the annular part <NUM> and the corresponding arched strut <NUM>. In embodiments, each pair of anchoring formations <NUM> extend bridge wise at an intra-strut location, that is a location within an arched strut <NUM> and as such comprised between two proximal ends <NUM> of the same arched strut <NUM> and under a distal end <NUM>/distal portion <NUM>. In other words, each set <NUM> of anchoring formations <NUM> extends bridge-wise from the arched strut <NUM> to a portion of the annular part <NUM> comprised between two proximal ends <NUM>.

The support posts <NUM>, accordingly, are arranged at an inter-strut location (e.g. above the inter-strut portion <NUM> as shown in the figures) so that the sequence post <NUM> - set <NUM> - post <NUM> - set <NUM> - post <NUM> - set <NUM> is provided, location-wise, as inter-strut - intra-strut - inter-strut - intra-strut - inter-strut - intra-strut.

In embodiments, the support posts <NUM> are provided with bores <NUM> configured for receiving sutures or stitches that fix the commissural portions (pleat formations of the valvular sleeve) to the posts <NUM>, hence fixing the prosthetic valve to the armature <NUM>. In some embodiments, the prosthetic valve is fixed to the support posts <NUM> with the same being completely outside of the valve. Sutures or stitches are routed through the bores <NUM> and through the valve layers contacting the corresponding post <NUM> from inside of the lumen. In other embodiments, the posts <NUM> may be wrapped by the valve layers - particularly by the commissural points of the valve - so that the valve is at least partially "outside" of the posts <NUM>.

In embodiments, the anchoring formations may include a serpentine or otherwise weaving portion between opposite ends thereof. Such a serpentine or otherwise weaving portion is intended to provide a larger footprint to the anchoring formation at the interface with a Valsalva Sinus, and additionally it enables the bulging of the anchoring formations to a diameter larger than the inflow diameter, typically <NUM> or <NUM> times the inflow diameter.

According to embodiments, a prosthesis <NUM> including portions thereof made of "dry" pericardium (or more in general of an implantable material ID comprising a decellularized sterilized mammalian tissue having an extracellular matrix, wherein a plurality of interstitial spaces of the extracellular matrix include a solution of one or more polyols) that has been subjected to a laser processing by the method according to embodiments therein provides unprecedented advantages in terms of storage. Since the "dry" pericardium/implantable material as disclosed herein does not require preservation in a liquid sterile solution, and - instead - it only requires an ethylene oxide sterilization similar to that commonly practiced on surgical instruments, various embodiments herein - with specific reference to <FIG> and <FIG> - may comprise a kit including a delivery instrument <NUM> with a heart valve prosthesis <NUM> pre-mounted/pre-loaded thereon, wherein the prosthesis <NUM> includes the leaflet <NUM> made of "dry" bovine pericardium or more in general of the implantable material ID comprising a decellularized sterilized mammalian tissue having an extracellular matrix, wherein a plurality of interstitial spaces of the extracellular matrix include a solution of one or more polyols.

With reference to <FIG> and <FIG>, a delivery instrument <NUM> according to embodiments of the kit includes a shaft having a longitudinal axis X100, a handle at a first end of the shaft; and a carrier portion P100 at a second end of the shaft. <FIG> and <FIG> only show the carrier portion P100 in that the handle-shaft-carrier portion layout is per se known in the art.

The carrier portion P100 is configured for holding an expandable heart valve prosthesis, such as the prosthesis <NUM> at least partly in a radially collapsed condition for delivery to the implantation site.

The carrier portion P100 may include a hub <NUM> fixed to the handle via the shaft, a first deployment element <NUM>, and a second deployment element <NUM>. Each of the first deployment element <NUM> and second deployment element <NUM> is configured to hold a corresponding portion of an expandable heart valve prosthesis in a radially collapsed condition.

In embodiments, the first deployment element <NUM> may be provided as a cup member featuring an ogee-like shape, preferably with a blunt end to avoid damaging to the patient's tissues and vasculature.

The first deployment element <NUM> of the carrier portion P100 is connected to a drive feature enabling it to slide along the axis X100 and operable through a drive member preferably located on the handle itself. The drive member may include a knob for operation by the practitioner.

Connection to the drive feature may occur for example via a connecting rod or shaft member <NUM> that is slidably arranged into the shaft of the delivery instrument <NUM>.

The second deployment element <NUM> may be - instead - provided as a sheath member including a plug <NUM> and a sheath <NUM> fitted onto the plug <NUM> (e.g. by interference fitting, or else thermally bonded thereto). The connecting rod or shaft member <NUM> may run through the plug <NUM> and the hub <NUM>, and be slidable relative thereto. The hub <NUM> may advantageously comprise radial guide blades <NUM> for the sheath <NUM>, and a locking feature <NUM>, particularly in the form of a locking flange or collar, configured to receive and lock a corresponding portion of the armature <NUM> of the valve prosthesis <NUM>.

The plug <NUM> is fixed to the handle via a drive feature enabling it to slide along the axis X100 and operable through a drive member preferably located on the handle itself. The drive member may include a knob for operation by the practitioner. In embodiments, each of the deployment elements <NUM>, <NUM> may be independently operable of each other, for example via individually operable drive members, so to independently control the releasing action provided thereby. In other embodiments, both deployment elements may be operatively connected to respective drive features, and be nevertheless operable via a single and common drive member. An example of such embodiments is disclosed in PCT application no. <CIT> in the name of the same Applicant.

Whatever the drive arrangement, the deployment instrument <NUM> is operable to delivery and release a heart valve prosthesis - such as the prosthesis <NUM> - including a radially contractible/radially expandable armature and a prosthetic valve carried thereby to an implantation site.

For this purpose, the deployment elements <NUM>, <NUM> of the carrier portion P100 are each operable from a respective first axial position wherein an overlap occurs with a respective portion of the heart valve prosthesis <NUM> loaded on the instrument <NUM> - particularly on the hub <NUM> of the carrier portion P100 - to hold the same portion in a radially collapsed condition, to a second position wherein no overlap occurs between the deployment element <NUM>, <NUM> and the prosthesis <NUM>, which is thus in a radially expanded condition.

In embodiments featuring a drive arrangement with a common drive for both the deployment elements <NUM>, <NUM>, these deployment elements are operable from a position of minimum (allowed) mutual distance condition, corresponding to both deployment elements <NUM>, <NUM> in the first operating position and associated to a loading/delivery operating condition of the prosthesis <NUM>, to a maximum (allowed) mutual distance condition corresponding to both deployment elements <NUM>, <NUM> in the second operating position and associated to complete valve deployment/release at the implantation site. The distance referred to is that along the axis X100.

In the embodiments referred to in <FIG> and <FIG>, the first deployment element <NUM> is associated to the inflow portion IF of the prosthesis <NUM>, while the second deployment element <NUM> is associated to the outflow portion OF of the heart valve prosthesis. In this latter regard, the ends <NUM> are received and locked onto the locking feature <NUM>, with the sheath <NUM> in overlapping condition when in the first position.

In embodiments herein, with reference to <FIG>, the kit may include the delivery instrument <NUM> with the prosthesis <NUM> pre-mounted/pre-loaded thereon with the outflow portion OF held in a radially contracted condition by the deployment element <NUM> in the respective first position, and the inflow portion IF held in a radially contracted condition by the deployment element <NUM> in the respective first position. The anchoring formations <NUM> are not subject to overlap by the deployment elements <NUM>, <NUM>, and as such are not subject to a direct radial contraction. An example of such a loading pattern is disclosed in <CIT> in the name of the same applicant, figure 3B thereof.

The pre-loading arrangement of <FIG> is applicable both in case of independently operable deployment elements <NUM>, <NUM> and in case of commonly driven deployment elements <NUM>, <NUM>.

The assembled kit may then be sterilized - for example by ethylene oxide - and packed for storage prior to use by the practitioner. In this way, the practitioner will be relieved from all of the crimping and loading operations as the kit will actually provide a ready to use facility. The "dry" implantable material ID exhibits excellent dry storage properties due, i. , to the presence of polyols (such as glycerol). The implantable material remains resilient and supple even after months of dry storage, and as such opens to the possibility of a joint storage with the delivery instrument <NUM>.

In other embodiments, with reference to <FIG>, the kit may include the delivery instrument <NUM> with the prosthesis <NUM> pre-mounted/pre-loaded thereon with the outflow portion OF held in a radially contracted condition by the deployment element <NUM> in the respective first position, and the inflow portion IF free of radial contraction by the deployment element <NUM>, which is accordingly in the respective second position. This arrangement may be applicable with independently operable deployment elements <NUM>, <NUM> and may be intended for long-term storage to minimize distortions of the leaflets <NUM> - provided that the same will be kept stored in a collapsed condition until the actual use of the kit.

Claim 1:
A method of providing features on an implantable material , the method comprising:
- providing an implantable material comprising a decellularized sterilized mammalian tissue having an extracellular matrix, wherein a plurality of interstitial spaces of the extracellular matrix include a solution of one or more polyols,
- providing one or more features on said implantable material by laser treatment,
wherein said laser treatment includes CO<NUM> laser treatment.