CA2257205C - Prosthetic heart valve - Google Patents
Prosthetic heart valve Download PDFInfo
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- CA2257205C CA2257205C CA002257205A CA2257205A CA2257205C CA 2257205 C CA2257205 C CA 2257205C CA 002257205 A CA002257205 A CA 002257205A CA 2257205 A CA2257205 A CA 2257205A CA 2257205 C CA2257205 C CA 2257205C
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- suture ring
- support housing
- adhesive
- ring
- suture
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Abstract
A cardiac valve prosthesis consists of a support housing (stent) to which ene or more flexible or stiff cusps and a suture ring are secured. Also disclosed are bioprostheses or mechanical valves with a support housing to which a suture ring is secured. In order to reliably secure the suture ring to the support housing outer surface, the suture ring is glued.
Description
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20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 DESCRIPTION
FR08TH$TIC HHART VALVB
The invention relates to a prosthetic heart valve comprised of a supporting housing (stent) to which one or more flexible or rigid cusps and a suture ring are fastened. Simultaneously, the invention relates to biprosthesis or mechanical valves with a support housing to which a suture ring is affixed. The heart valve known, for example, from DE 38 34 545 C2 is comprised of a support housing composed a cylindrical base ring which is provided along its periphery with three axially tapering posts [stays] offset about the periphery respectively by 120°. The wall end facets lying between the posts serve to take up and secure three cusps [leaflets] which insure the closing and opening of the heart valve.
In the closed state, the cusps [leaflets] lie against one another along their free ends and form together in overlapping region.
Apart from the aforedescribed aortic valve, so-called mitral valves are known which instead of having three cusps [leaflets], have only two cusps [leaflets].
So that the heart valve is well matched to the annulus and can be fastened in place, prosthetic heart valves have suture rings which are affixed on the outer periphery of the housing, approximately at the level of the inflow plane. The suture ring can be sutured after implantation with the tissue of the patient in order to anchor the prosthetic heart valve fixedly in its implanted position.
20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 EP 0 443 993 B1, as has already been indicated, discloses suture rings which are coated or completely formed of a biocompatible synthetic tissue and have the advantage that the slidability for the needles and the stitching threads can be improved, thereby simplifying the suturing into the annulus tissue although with the drawback that blood absorbing, hemolytic or thrombogenic effects can result. To avoid these, a liquid repellent material, like for example, polytetrafluoroethylene (Teflon) can be used. The use of such liquid repellent materials, however, is contradictory to the requirement that the outer region of the suture ring enable growth into the patient tissue. In order to satisfy these different requirements, according to the afore-mentioned patent, the suture ring can be comprised of a composite body of two materials, of which the first is substantially hemocompatible so that it does not absorb substantially any blood and has a reduced hemolytic and thrombogenic effect, while the second material is substantially hydrophilic and porous so that growth into the patient tissue is promoted. The first material is applied on the respective end sides of the suture ring and the second material on the peripheral surface. A drawback of this construction of such a suture ring is that it is expensive and is only limitedly satisfactory from the point of view of the shear forces or torsion forces which arise with respect to insufficient stability.
T u~. . .'. v : '~ L ~', ~ : ;.
20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 DESCRIPTION
FR08TH$TIC HHART VALVB
The invention relates to a prosthetic heart valve comprised of a supporting housing (stent) to which one or more flexible or rigid cusps and a suture ring are fastened. Simultaneously, the invention relates to biprosthesis or mechanical valves with a support housing to which a suture ring is affixed. The heart valve known, for example, from DE 38 34 545 C2 is comprised of a support housing composed a cylindrical base ring which is provided along its periphery with three axially tapering posts [stays] offset about the periphery respectively by 120°. The wall end facets lying between the posts serve to take up and secure three cusps [leaflets] which insure the closing and opening of the heart valve.
In the closed state, the cusps [leaflets] lie against one another along their free ends and form together in overlapping region.
Apart from the aforedescribed aortic valve, so-called mitral valves are known which instead of having three cusps [leaflets], have only two cusps [leaflets].
So that the heart valve is well matched to the annulus and can be fastened in place, prosthetic heart valves have suture rings which are affixed on the outer periphery of the housing, approximately at the level of the inflow plane. The suture ring can be sutured after implantation with the tissue of the patient in order to anchor the prosthetic heart valve fixedly in its implanted position.
20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 EP 0 443 993 B1, as has already been indicated, discloses suture rings which are coated or completely formed of a biocompatible synthetic tissue and have the advantage that the slidability for the needles and the stitching threads can be improved, thereby simplifying the suturing into the annulus tissue although with the drawback that blood absorbing, hemolytic or thrombogenic effects can result. To avoid these, a liquid repellent material, like for example, polytetrafluoroethylene (Teflon) can be used. The use of such liquid repellent materials, however, is contradictory to the requirement that the outer region of the suture ring enable growth into the patient tissue. In order to satisfy these different requirements, according to the afore-mentioned patent, the suture ring can be comprised of a composite body of two materials, of which the first is substantially hemocompatible so that it does not absorb substantially any blood and has a reduced hemolytic and thrombogenic effect, while the second material is substantially hydrophilic and porous so that growth into the patient tissue is promoted. The first material is applied on the respective end sides of the suture ring and the second material on the peripheral surface. A drawback of this construction of such a suture ring is that it is expensive and is only limitedly satisfactory from the point of view of the shear forces or torsion forces which arise with respect to insufficient stability.
In EP 0 443 994 B1, a suture ring is proposed which has a core and an internal edge bead engaged in a groove of the outer wall of the support housing. Outwardly of this engagement region, the suture ring is provided with a coating which is so obtained that the contact between this coating and support housing outer wall surfaces insures a sufficiently great resistance against relative rotation of the suture ring and the support housing. This suture ring also has the aforedescribed drawbacks.
Further core-sheath restructures of the suture ring have already been described for example in EP 0 119 357 A1, in EP 0 075 530 A1, in GB 2 021 530 A1 and in EP 0 145 166 A2. In the last-mentioned publication, the core ring is comprised of a memory alloy which is so selected and treated that the body temperature of the patient generates a core-ring contraction which gives rise to a sufficient clamping force effect.
DE-A 1 180 087 describes a heart valve prosthesis with a valve body, a valve member movable relative to the valve body and a fixing ring serving for attachment of the prosthesis which is formed as an independent component and is connectable with the valve body. The connection of the valve body and the fixing can either be nonreleasable, for example, by cementing or welding, or releaseable, for example by a form connection or plug connection of a bayonette joint. The part of the fixing ring remote from the valve body is encased with a coarse, mesh synthetic fabric, for example, knit polytetrafluoroethylene which is rolled up into a loose cushion and with the aid of a strong thread is held together.
A broad aspect of the invention provides a prosthetic heart valve comprised of a support housing to which at least one cusp and a suture ring are fastened, characterized in that the suture ring is cemented by an adhesive to the support housing, wherein the suture ring, the at least one cusp and outer surfaces of the support housing are composed of the same material.
Another broad aspect of the invention provides a process of producing the prosthetic heart valve as aforesaid, characterized in that a suture ring blank is prefabricated by injecting a suture ring material, upon a substantially planar surface like a glass plate or on a hose cylinder shell and then the suture ring blank is cut or stamped to the suture ring of a desired size, before the suture ring is cemented to the support housing, and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
A further broad aspect of the invention provides a process for producing the prosthetic heart valve as aforesaid, characterized in that the suture ring is injected directly in a desired width and thickness on the support housing and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
It is the object of the present invention to provide a prosthetic heart valve of the originally mentioned type, whose suture ring is securely affixed on the outer wall of the support housing, whereby the suture ring has a sufficient slidability for the needle and thread used to suture the ring in the annulus, as well as a sufficient flexibility. The suture ring structure should, finally, be suitable for growth with the body tissue of the patient.
By contradistinction to the known connections up to now according to the state of the art, which rely upon a force or friction connection or a form-fitting setting arrangement or a combination of two, with an adhesive bonding, not only is a reliable, durable fixation of the suture ring on the heart valve support housing effected, but also the suture ring construction is simplified and can be of suitable biocompatible material. Because of the condition which can be assured that the adhesive which is used will not come into contact with the patients' tissue or the patients' blood, practically any adhesive known from the state of the art, for example, an epoxy resin, can be used.
According to a feature of the invention, however, the adhesive material is the same material, preferably polyurethane, as is used to also comprise the support housing and/or the suture ring. If, for example, the cusps [leaflets] are also composed of polyurethane, the entire heart valve can be fabricated from a single material which effectively avoids material stresses especially as a consequence of different thermal expansion coefficients (before, during and after implantation).
According to a further feature of the invention, the adhesive bond between the suture ring and the support housing is sealed toward the exterior, i.e, at the interfacial edges.
4a 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 The suture ring is comprised preferably from a microporous, fine fibrillar structure which promotes growth with the intrinsic body tissue of the patient. If necessary or if desired, a local intergrowth with intrinsic body tissue of the patient can be targeted at certain locations of the suture ring by sealing (coating) at areas targeted for suppression, for example, to hinder the growth of tissue into the inflow cross section.
According to the invention, a number of processes are available for production of the aforedescribed new heart valve.
In a first process variant, a suture ring blank is prefabricated by spraying the suture ring material which preferably is comprised of polyurethane, on a glass plate or a hose cylinder wall. This suture ring blank is then cut or stamped to a desired suture ring size and suture ring shape after removal from the glass plate or the hose cylinder wall, before the finished suture ring is cemented to the support housing.
The cementing can be effected in that adhesive is coated onto the support housing wall outer surface which is provided and the suture ring is then shoved onto the adhesive coated surface, positioned and the adhesive permitted to dry.
Alternatively thereto, it is possible to shove the prefabricated suture ring onto the support housing surface which is provided, to orient the suture ring and then to lift the inner wall of the suture ring around the support housing at least at several locations therefrom and to fill adhesive into the intervening space before the adhesive is dried. It is also possible to apply the adhesive, after the suture ring has been shoved onto the support housing surface and oriented thereon, by means of a cannula at the common contact surface of the suture ring and the support housing by injection of the adhesive, and allowing the adhesive to dry. In this possible variant of the method, before the suture ring is shoved onto the support housing surface, the latter can be sprayed or coated with adhesive to yield a first adhesive layer thereon.
An alternative fabrication of the prosthetic heart valve is described, whereby the suture ring is directly injected [sprayed] with the desired width and thickness on the support housing. In this case, preferably around the annular surface which is provided to receive the suture ring, the remainder of the supporting housing is masked by injection [spraying] so that only in the region of the supporting housing that the suture ring application is to occur can such an application be applied. The masking material for the remainder of the support housing at least at the edge which is to define the free annular surface of the suture ring, has a thickness which corresponds to the desired sutured ring thickness.
If one selects, as has already been indicated above, a material for the suture ring which is the same material as for the support housing, especially polyurethane, be appropriate practice 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 of the process, a stable cross linking can be achieved at the bonding locations of the suture ring with the support housing so that a unitary body of a single material is obtained with a simple suture ring construction.
Embodiments of the invention are shown in the drawing.
It shows:
FIG. 1 a perspective view of a three-cusp aortic valve (without suture ring), FIG. 2 a section along the plane A-A in FIG.1, FIG. 3 a perspective view of a two-cusp mitral valve (without suture ring), FIG. 4 a section along the line B-B in FIG. 3, FIG. 5 a perspective view of a further mitral valve, and FIG. 6 is a plan view of the mitral valve according to FIG. 5 without suture ring.
The heart valve shown in FIGS. 1 and 2 is comprised substantially of a support housing 10 with three cusps [leaflets]
11 which are affixed on the radially outwardly disposed inclined surfaces, namely, the end surfaces 12; of the wall 13 of the support housing. The support housing 10 has a base ring 14 whose diameter determines the valve throughput and is rounded at its inner wall edge in the inlet region. The wall 13 is substantially perpendicular to the base ring ground surface, whereby three tips 15 project as posts at an angular offset of 120° from one another and between which the end face 12 of the wall 13 runs in circular 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 arc form. The inner edges of these end surfaces 12 between two posts lies in a respective plane which is defined as an intersection of a cylinder with a plane inclined to its longitudinal axis as a result, an angle of attack of the three planes of about 8~0° relative to the base ring ground surface results. The support housing is comprised of elastic synthetic resin. It can be a thermoplast like polyamide which is produced, for example, by injection molding and can be coated with polyurethane after roughening of the surface. The cusps 11 [leaflets] are comprised of a flexible thin synthetic resin foil which preferably also are fabricated from polyurethane. The wall 13 has an outer smooth and straight portion and serves as is visible from FIG. 2 to enable a suture ring 16, which has a substantially hollow cylindrical form, to be affixed thereto, the suture ring 16 having on its two end edges, ring-shaped beads.
This suture ring material is also comprised of polyurethane.
To fabricate the aorta valve illustrated, the support housing 10 is injection molded and is initially provided with the three cusps 11 [leaflets] which can be cemented on the end surfaces 12. The cusps [leaflets] themselves have been previously cut from a planar polyurethane foil. Then, either the already prefabricated suture ring is cemented onto the support housing outer wall in the region of the base ring 14 or injected directly onto the latter.
In the first case, the suture ring is initially injected onto a glass plate or hose-shaped cylindrical body from a fleece with _ g _ 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 microporous fine fibrillar structure. After cutting of the prefabricated part into the desired suture ring shape and sealing possible cut edges were desired, the suture ring is pressed onto the outer wall of the support housing 10 at the level of the base ring 14, is oriented there and then adhesive is injected between the suture ring and the support housing 10. Alternatively or additionally, before the suture ring 16 is pressed onto the carrying surface and oriented thereon, this region can be coated with adhesive. In a treatment variant, the side turned toward the flow and the side turned away from the flow of the transition zone between the suture ring 16 and the outer wall of the support housing 10, can be annularly sealed with adhesive.
The mitral heart valve illustrated in FIGS. 3 and 4 is comprised of a support housing 20 with two cusps [leaflets] 21 and a suture ring 22 which is affixed along the outer wall at the level of the inlet region of the support housing 20. The one piece support housing 20 has a base ring 23 whose inner edges in the inlet region are rounded in a manner known from the state of the art. The wall 24 which extends substantially perpendicular to the base ring ground surface, is subdivided into a first wall with reduced curvature and a second wall with greater curvature which together in plan view onto the base ground surface, define two semi-ellipses with a common longitudinal axes. The half transverse axes can be of different length, preferably with a length ratio of 1:2. The upper end surface 26 of the wall 24 _ g _ 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 serves as a fastening surface for the cusps [leaflets] 21. Each of the two end surfaces 26 between two posts 25 has an inner edge at an inclination to the base ring ground surface which forms the inlet region. In the present case, the connecting lines between the cusps [leaflets] 21 and the upper inner edges of the wall 24 each lie in a plane which runs at an angle of about 50° or about 35° with respect to the base ring ground surface. The cusp settings are therefore different. The posts 25 have a prismatic contour and widen uniformly to their upper end surfaces 27 which are substantially triangular. In a plan view of the inner wall of the support housing 10 (see FIG., 4) it can be seen that the posts are V-shaped and end in a wedge configuration above the base ring base surface in the inlet region of the support housing 10. The cross sections of the posts 25 parallel to the base ring ground surface forms a substantially equilateral triangle. The post axes 28 are not vertical relative to the base ring ground surfaces, but are slightly inclined with respect to surface normals, especially with an angle of 15°. A corresponding inclination is shown by the end face 27 of the post [stay] relative to the base ring ground surface. The posts 25 replace the commissure regions of the natural heart valve and serve as prismatic inner seats for the cusps [leaflets] 21 with their unilateral triangular shanks.
A further form of mitral valve is shown in FIG. 5. In contradistinction to the mitral valve shown in FIGS. 3 and 4, the posts in the walling 30 are integrated with equal thickness. In 20902 PCT/DE97/01299 ~ Transl. of PCT/DE97/01299 the regions of the aforedescribed posts, the wall has its greatest height, measured from the base ring, and ends either at an acute angle or as has been shown in FIGS. 5 and 6, in a flattening 31.
The posts do not extend any longer geometrically "out of the walls". The walling 30 is thicker between the two post regions than in the remainder of the posts (see reference character 31).
In contradistinction to the suture ring shown in FIG. 2, the suture ring 22 according to FIG. 4, on anatomical grounds, for reducing the suturing stresses, is wide edged and in the form~of a suturing cap. This so-called super annular construction is preferred for mitral heart valves. The fastening of the suturing 22 corresponds to that described previously with respect to the aorta valve.
The advantages of the fleece-like suture rings of polyurethane which are used lie in their good surgical manipulability with respect to the smoothness of the material upon suturing. It is also possible to process the suture ring already affixed to the support housing prior to the implantation by cutting in order to insure a better match in the annulus of the patient.
The polyurethane suture ring has a good wear resistance and a high elasticity. Furthermore, the polyurethane suture ring is also characterized by good hemocompatability. Because of the microfibrillar structure, a rapid and above a control healing with surrounding tissue of the patient is possible. There is only a very thin formation of neointima, a formation of giant cells and 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 excessive pannus are avoided. Thromboambolytic complications are also reduced as is the risk of perivalvular leaks and endocarditis.
The tissue tolerance of the suture ring is good.
A further advantage resides in that the entire valve can be comprised on its surface of the same material. The fabrication and bonding of the suture ring to the stent is simplified and a large number of steps is not required. The number of elements which must be used is small and the elastic structure of the suture ring gives rise to a secure fixation of the suture ring wherever it lies in contact with the support housing. The process of the invention enables production of a suitable prosthesis (fabrication of the support housing with cusps [leaflets]) separately and a reduced cost for the production of the suture ring and it is relative simple assembly of the suture ring with the support housing by cementing.
In the fabrication of the described heart valve, the cusps [leaflets] which have been previously formed can be affixed by cementing or welding onto the end surfaces of the support housing. Alternatively, it is also possible to fabricate the heart valve by the injection molding technique known from the art, including two component injection, in which initially the support housing is made and then the cusps [leaflets] are applied by injection molding. A further possibility is the use of so-called immersion technique. In this process the support housing which may be made from polyamide, after a coating with polyurethane can be 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 shoved onto a corresponding mandrel having forming surfaces for the cusps [leaflets] and the mandrel with the support housing is immersed in a liquid synthetic resin solution (polyurethane) and tumbled therein until the desired thickness distributions is reached. During the tumbling, the synthetic resin hardens.
On the thus fabricated unit of support housing and cusp or cusps [leaflets], the suture ring is fastened in the above-described manner.
Further core-sheath restructures of the suture ring have already been described for example in EP 0 119 357 A1, in EP 0 075 530 A1, in GB 2 021 530 A1 and in EP 0 145 166 A2. In the last-mentioned publication, the core ring is comprised of a memory alloy which is so selected and treated that the body temperature of the patient generates a core-ring contraction which gives rise to a sufficient clamping force effect.
DE-A 1 180 087 describes a heart valve prosthesis with a valve body, a valve member movable relative to the valve body and a fixing ring serving for attachment of the prosthesis which is formed as an independent component and is connectable with the valve body. The connection of the valve body and the fixing can either be nonreleasable, for example, by cementing or welding, or releaseable, for example by a form connection or plug connection of a bayonette joint. The part of the fixing ring remote from the valve body is encased with a coarse, mesh synthetic fabric, for example, knit polytetrafluoroethylene which is rolled up into a loose cushion and with the aid of a strong thread is held together.
A broad aspect of the invention provides a prosthetic heart valve comprised of a support housing to which at least one cusp and a suture ring are fastened, characterized in that the suture ring is cemented by an adhesive to the support housing, wherein the suture ring, the at least one cusp and outer surfaces of the support housing are composed of the same material.
Another broad aspect of the invention provides a process of producing the prosthetic heart valve as aforesaid, characterized in that a suture ring blank is prefabricated by injecting a suture ring material, upon a substantially planar surface like a glass plate or on a hose cylinder shell and then the suture ring blank is cut or stamped to the suture ring of a desired size, before the suture ring is cemented to the support housing, and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
A further broad aspect of the invention provides a process for producing the prosthetic heart valve as aforesaid, characterized in that the suture ring is injected directly in a desired width and thickness on the support housing and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
It is the object of the present invention to provide a prosthetic heart valve of the originally mentioned type, whose suture ring is securely affixed on the outer wall of the support housing, whereby the suture ring has a sufficient slidability for the needle and thread used to suture the ring in the annulus, as well as a sufficient flexibility. The suture ring structure should, finally, be suitable for growth with the body tissue of the patient.
By contradistinction to the known connections up to now according to the state of the art, which rely upon a force or friction connection or a form-fitting setting arrangement or a combination of two, with an adhesive bonding, not only is a reliable, durable fixation of the suture ring on the heart valve support housing effected, but also the suture ring construction is simplified and can be of suitable biocompatible material. Because of the condition which can be assured that the adhesive which is used will not come into contact with the patients' tissue or the patients' blood, practically any adhesive known from the state of the art, for example, an epoxy resin, can be used.
According to a feature of the invention, however, the adhesive material is the same material, preferably polyurethane, as is used to also comprise the support housing and/or the suture ring. If, for example, the cusps [leaflets] are also composed of polyurethane, the entire heart valve can be fabricated from a single material which effectively avoids material stresses especially as a consequence of different thermal expansion coefficients (before, during and after implantation).
According to a further feature of the invention, the adhesive bond between the suture ring and the support housing is sealed toward the exterior, i.e, at the interfacial edges.
4a 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 The suture ring is comprised preferably from a microporous, fine fibrillar structure which promotes growth with the intrinsic body tissue of the patient. If necessary or if desired, a local intergrowth with intrinsic body tissue of the patient can be targeted at certain locations of the suture ring by sealing (coating) at areas targeted for suppression, for example, to hinder the growth of tissue into the inflow cross section.
According to the invention, a number of processes are available for production of the aforedescribed new heart valve.
In a first process variant, a suture ring blank is prefabricated by spraying the suture ring material which preferably is comprised of polyurethane, on a glass plate or a hose cylinder wall. This suture ring blank is then cut or stamped to a desired suture ring size and suture ring shape after removal from the glass plate or the hose cylinder wall, before the finished suture ring is cemented to the support housing.
The cementing can be effected in that adhesive is coated onto the support housing wall outer surface which is provided and the suture ring is then shoved onto the adhesive coated surface, positioned and the adhesive permitted to dry.
Alternatively thereto, it is possible to shove the prefabricated suture ring onto the support housing surface which is provided, to orient the suture ring and then to lift the inner wall of the suture ring around the support housing at least at several locations therefrom and to fill adhesive into the intervening space before the adhesive is dried. It is also possible to apply the adhesive, after the suture ring has been shoved onto the support housing surface and oriented thereon, by means of a cannula at the common contact surface of the suture ring and the support housing by injection of the adhesive, and allowing the adhesive to dry. In this possible variant of the method, before the suture ring is shoved onto the support housing surface, the latter can be sprayed or coated with adhesive to yield a first adhesive layer thereon.
An alternative fabrication of the prosthetic heart valve is described, whereby the suture ring is directly injected [sprayed] with the desired width and thickness on the support housing. In this case, preferably around the annular surface which is provided to receive the suture ring, the remainder of the supporting housing is masked by injection [spraying] so that only in the region of the supporting housing that the suture ring application is to occur can such an application be applied. The masking material for the remainder of the support housing at least at the edge which is to define the free annular surface of the suture ring, has a thickness which corresponds to the desired sutured ring thickness.
If one selects, as has already been indicated above, a material for the suture ring which is the same material as for the support housing, especially polyurethane, be appropriate practice 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 of the process, a stable cross linking can be achieved at the bonding locations of the suture ring with the support housing so that a unitary body of a single material is obtained with a simple suture ring construction.
Embodiments of the invention are shown in the drawing.
It shows:
FIG. 1 a perspective view of a three-cusp aortic valve (without suture ring), FIG. 2 a section along the plane A-A in FIG.1, FIG. 3 a perspective view of a two-cusp mitral valve (without suture ring), FIG. 4 a section along the line B-B in FIG. 3, FIG. 5 a perspective view of a further mitral valve, and FIG. 6 is a plan view of the mitral valve according to FIG. 5 without suture ring.
The heart valve shown in FIGS. 1 and 2 is comprised substantially of a support housing 10 with three cusps [leaflets]
11 which are affixed on the radially outwardly disposed inclined surfaces, namely, the end surfaces 12; of the wall 13 of the support housing. The support housing 10 has a base ring 14 whose diameter determines the valve throughput and is rounded at its inner wall edge in the inlet region. The wall 13 is substantially perpendicular to the base ring ground surface, whereby three tips 15 project as posts at an angular offset of 120° from one another and between which the end face 12 of the wall 13 runs in circular 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 arc form. The inner edges of these end surfaces 12 between two posts lies in a respective plane which is defined as an intersection of a cylinder with a plane inclined to its longitudinal axis as a result, an angle of attack of the three planes of about 8~0° relative to the base ring ground surface results. The support housing is comprised of elastic synthetic resin. It can be a thermoplast like polyamide which is produced, for example, by injection molding and can be coated with polyurethane after roughening of the surface. The cusps 11 [leaflets] are comprised of a flexible thin synthetic resin foil which preferably also are fabricated from polyurethane. The wall 13 has an outer smooth and straight portion and serves as is visible from FIG. 2 to enable a suture ring 16, which has a substantially hollow cylindrical form, to be affixed thereto, the suture ring 16 having on its two end edges, ring-shaped beads.
This suture ring material is also comprised of polyurethane.
To fabricate the aorta valve illustrated, the support housing 10 is injection molded and is initially provided with the three cusps 11 [leaflets] which can be cemented on the end surfaces 12. The cusps [leaflets] themselves have been previously cut from a planar polyurethane foil. Then, either the already prefabricated suture ring is cemented onto the support housing outer wall in the region of the base ring 14 or injected directly onto the latter.
In the first case, the suture ring is initially injected onto a glass plate or hose-shaped cylindrical body from a fleece with _ g _ 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 microporous fine fibrillar structure. After cutting of the prefabricated part into the desired suture ring shape and sealing possible cut edges were desired, the suture ring is pressed onto the outer wall of the support housing 10 at the level of the base ring 14, is oriented there and then adhesive is injected between the suture ring and the support housing 10. Alternatively or additionally, before the suture ring 16 is pressed onto the carrying surface and oriented thereon, this region can be coated with adhesive. In a treatment variant, the side turned toward the flow and the side turned away from the flow of the transition zone between the suture ring 16 and the outer wall of the support housing 10, can be annularly sealed with adhesive.
The mitral heart valve illustrated in FIGS. 3 and 4 is comprised of a support housing 20 with two cusps [leaflets] 21 and a suture ring 22 which is affixed along the outer wall at the level of the inlet region of the support housing 20. The one piece support housing 20 has a base ring 23 whose inner edges in the inlet region are rounded in a manner known from the state of the art. The wall 24 which extends substantially perpendicular to the base ring ground surface, is subdivided into a first wall with reduced curvature and a second wall with greater curvature which together in plan view onto the base ground surface, define two semi-ellipses with a common longitudinal axes. The half transverse axes can be of different length, preferably with a length ratio of 1:2. The upper end surface 26 of the wall 24 _ g _ 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 serves as a fastening surface for the cusps [leaflets] 21. Each of the two end surfaces 26 between two posts 25 has an inner edge at an inclination to the base ring ground surface which forms the inlet region. In the present case, the connecting lines between the cusps [leaflets] 21 and the upper inner edges of the wall 24 each lie in a plane which runs at an angle of about 50° or about 35° with respect to the base ring ground surface. The cusp settings are therefore different. The posts 25 have a prismatic contour and widen uniformly to their upper end surfaces 27 which are substantially triangular. In a plan view of the inner wall of the support housing 10 (see FIG., 4) it can be seen that the posts are V-shaped and end in a wedge configuration above the base ring base surface in the inlet region of the support housing 10. The cross sections of the posts 25 parallel to the base ring ground surface forms a substantially equilateral triangle. The post axes 28 are not vertical relative to the base ring ground surfaces, but are slightly inclined with respect to surface normals, especially with an angle of 15°. A corresponding inclination is shown by the end face 27 of the post [stay] relative to the base ring ground surface. The posts 25 replace the commissure regions of the natural heart valve and serve as prismatic inner seats for the cusps [leaflets] 21 with their unilateral triangular shanks.
A further form of mitral valve is shown in FIG. 5. In contradistinction to the mitral valve shown in FIGS. 3 and 4, the posts in the walling 30 are integrated with equal thickness. In 20902 PCT/DE97/01299 ~ Transl. of PCT/DE97/01299 the regions of the aforedescribed posts, the wall has its greatest height, measured from the base ring, and ends either at an acute angle or as has been shown in FIGS. 5 and 6, in a flattening 31.
The posts do not extend any longer geometrically "out of the walls". The walling 30 is thicker between the two post regions than in the remainder of the posts (see reference character 31).
In contradistinction to the suture ring shown in FIG. 2, the suture ring 22 according to FIG. 4, on anatomical grounds, for reducing the suturing stresses, is wide edged and in the form~of a suturing cap. This so-called super annular construction is preferred for mitral heart valves. The fastening of the suturing 22 corresponds to that described previously with respect to the aorta valve.
The advantages of the fleece-like suture rings of polyurethane which are used lie in their good surgical manipulability with respect to the smoothness of the material upon suturing. It is also possible to process the suture ring already affixed to the support housing prior to the implantation by cutting in order to insure a better match in the annulus of the patient.
The polyurethane suture ring has a good wear resistance and a high elasticity. Furthermore, the polyurethane suture ring is also characterized by good hemocompatability. Because of the microfibrillar structure, a rapid and above a control healing with surrounding tissue of the patient is possible. There is only a very thin formation of neointima, a formation of giant cells and 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 excessive pannus are avoided. Thromboambolytic complications are also reduced as is the risk of perivalvular leaks and endocarditis.
The tissue tolerance of the suture ring is good.
A further advantage resides in that the entire valve can be comprised on its surface of the same material. The fabrication and bonding of the suture ring to the stent is simplified and a large number of steps is not required. The number of elements which must be used is small and the elastic structure of the suture ring gives rise to a secure fixation of the suture ring wherever it lies in contact with the support housing. The process of the invention enables production of a suitable prosthesis (fabrication of the support housing with cusps [leaflets]) separately and a reduced cost for the production of the suture ring and it is relative simple assembly of the suture ring with the support housing by cementing.
In the fabrication of the described heart valve, the cusps [leaflets] which have been previously formed can be affixed by cementing or welding onto the end surfaces of the support housing. Alternatively, it is also possible to fabricate the heart valve by the injection molding technique known from the art, including two component injection, in which initially the support housing is made and then the cusps [leaflets] are applied by injection molding. A further possibility is the use of so-called immersion technique. In this process the support housing which may be made from polyamide, after a coating with polyurethane can be 20902 PCT/DE97/01299 Transl. of PCT/DE97/01299 shoved onto a corresponding mandrel having forming surfaces for the cusps [leaflets] and the mandrel with the support housing is immersed in a liquid synthetic resin solution (polyurethane) and tumbled therein until the desired thickness distributions is reached. During the tumbling, the synthetic resin hardens.
On the thus fabricated unit of support housing and cusp or cusps [leaflets], the suture ring is fastened in the above-described manner.
Claims (12)
1. A prosthetic heart valve comprised of a support housing to which at least one cusp and a suture ring are fastened, characterized in that the suture ring is cemented by an adhesive to the support housing, wherein the suture ring, the at least one cusp and outer surfaces of the support housing are composed of the same material.
2. The heart valve according to claim 1, characterized in that the suture ring, the at least one cusp, the outer surfaces of the support housing and the adhesive are comprised of polyurethane.
3. The heart valve according to claim 1 or claim 2, characterized in that an adhesive bond between the suture ring and the support housing is sealed toward the exterior.
4. The heart valve according to any one of claims 1 to 3, characterized in that the suture ring has a microporous, fine fibrillar structure.
5. A process of producing the prosthetic heart valve according to any one of the claims 1 to 4, characterized in that a suture ring blank is prefabricated by injecting a suture ring material, upon a substantially planar surface like a glass plate or on a hose cylinder shell and then the suture ring blank is cut or stamped to the suture ring of a desired size, before the suture ring is cemented to the support housing, and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
6. The process according to claim 5, characterized in that the adhesive is coated onto the outer surfaces of the support housing which are provided and the suture ring is shoved onto the outer surfaces of the support housing which is coated with the adhesive, aligned and the adhesive is then dried.
7. The process according to claim 5, characterized in that the suture ring is shoved onto the outer surfaces of the support housing which are provided and then an inner wall of the suture ring is raised around the support housing and the adhesive is filled into an intervening space and then the adhesive is dried.
8. The process according to claim 5, characterized in that the suture ring is shoved onto the outer surfaces of the support housing which are provided and is aligned, the adhesive then being injected by means of a cannula on common abutment surfaces of the suture ring and the support housing and the adhesive is then dried.
9. A process according to claim 5, characterized in that before the suture ring is shoved onto the outer surfaces of the support housing which are provided, the latter are sprayed with the adhesive and a first adhesive layer is thus applied.
10. A process for producing the prosthetic heart valve according to any one of claims 1 through 4, characterized in that the suture ring is injected directly in a desired width and thickness on the support housing and in that the outer surfaces of the support housing, the at least one cusp and the suture ring are made of the same material.
11. The process according to claim 10, characterized in that ring surfaces remaining beyond those provided for application of the suture ring are masked by spraying.
12. The process according to claim 10, characterized in that a masking material for a remainder of the support housing at least at the edge of an annular surface which is free to receive the suture ring, has a thickness which corresponds to the desired suture ring thickness.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19624951A DE19624951A1 (en) | 1996-06-24 | 1996-06-24 | Prosthetic heart valve |
| DE19624951.1 | 1996-06-24 | ||
| PCT/DE1997/001299 WO1997049357A1 (en) | 1996-06-24 | 1997-06-18 | Cardiac valve prosthesis |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2257205A1 CA2257205A1 (en) | 1997-12-31 |
| CA2257205C true CA2257205C (en) | 2005-11-22 |
Family
ID=35474954
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002257205A Expired - Fee Related CA2257205C (en) | 1996-06-24 | 1997-06-18 | Prosthetic heart valve |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2257205C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2915678B1 (en) | 2007-05-02 | 2010-04-16 | Lapeyre Ind Llc | MECHANICAL PROTHETIC CARDIAC VALVE |
-
1997
- 1997-06-18 CA CA002257205A patent/CA2257205C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2257205A1 (en) | 1997-12-31 |
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| EEER | Examination request | ||
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