PROSTHETIC ANNULUS FOR MITRAL OR TRICUSPID ANNULOPLASTY
The invention concerns a prosthetic annulus for mitr or tricuspid annuloplasty, designed for surgical reconstruction of diseased and/or damaged mitral and tricuspid valves.
A cardiac valve may become insufficient due to vario diseases, and it is then sometimes necessary to repair the fibromuscular annulus surrounding the valves to palliate the distortion of the valve without replacing it with a total artificial heart valve prosthesis.
Two main types of prosthetic annulus are currently available: the rigid rings, open or closed, for example, FR-A 2 031 699 and FR-A 2 071 172 of Carpentier; the flexible rings, adjustable like the Massana US-A 4 290 151 Both types of annulus are cloth-covered for suturing.
The Carpentier mitral ring has its open part located on the approximately straight part of the roughly bean- shaped annulus. This straight part rests on the fibrous trigone.
The Massana flexible rings are adjustable, by pulling the free ends of a folded thread, thus allowing the choice of the proper size at the location of use, and to comply with the shape of the damaged annulus.
However, once they have been sutured to the natural valvular annulus, both types of ring become rigid and inflexible, which prevents their complying with the heart's movements.
The invention palliates this disadvantage in providin a prosthetic ring for mitral and/or tricuspid annuloplasty. It consists of a core and a cloth sheath for suturing. Th core forms a complete ring with a rigid part and a part made of elastic material. The rigid part is made to rest on the corresponding fibrous trigone.
In the case of mitral annuloplasty, the rigid part of the core corresponds to the mitral anterior leaflet implantation, against the rigid fibrous trigone, sticking approximately to the straight part. The rigid part of the
Carpentier annulus is sometimes open in this area. The elastic part of the core of the present invention corresponds to the mitral posterior leaflet implantation, against the contractible wall of the heart.
Likewise, for the tricuspid valve ring reconstruction, the rigid part of the prosthetic annulus according to the present invention rests on the septal leaflet against the fibrous trigone, whereas the elastic part rests on the anterior and posterior leaflets' implantation.
The ring of the present invention shall now be described in detail, with reference to the following figures, in which: Fig. 1 is a diagrammatic view of a cross section of the heart, showing the location of the mitral and tricuspi valves; Fig. 2 is a section view of a mitral prosthetic annulus; and
Fig. 3 is a section view of a tricuspid prosthetic annulus. Figure 1 shows the cardiac anatomy of the mitral and tricuspid valves section. The mitral valve 1 consists of the anterior leaflet la and posterior leaflet lb and is surrounded by the mitral annulus 2. The mitral valve 1 i limited on the side of the anterior leaflet by the right 3 and left 3b fibrous trigone. The part of the prosthetic annulus which corresponds to the positioning of the posterior leaflet is the compliant one.
The tricuspid valve 4 is divided into three leaflets, the septal leaflet 4a, the anterior leaflet 4b and the posterior leaflet 4c. Only the septal leaflet 4a is in contact with the left fibrous trigone 3b. The natural valve ring shown at 5 is not a continuous fibrous annulus. The anterior and posterior leaflets are attached to the myocardium. Therefore, most often it is in this area that the tricuspid annulus strains itself and induces valvular insufficiency.
Figures 2 and 3 show diagrammatically and respectivel a mitral reconstruction annulus 6, and a tricuspid reconstruction annulus 7. Each of these rings has an elastic core but possesses a rigid insert 6a and 7a, respectively, inside the ring where the ring will be sutured to the fibrous trigone. The fibrous trigone area is not contractible and the reconstruction annulus may be rigid in this area. On the other hand, the remaining part of the ring which is to be in contact with the contractibl areas of the heart is elastic in order to comply with the heart completely.
Around the core, the rings of this invention have a tubular woven cloth sheath which allows the ring to be sutured to the natural valvular annulus. (This tubular cloth sheath does not show in the figures) . The elastic part of the rings is made of cloth, elastomer or a similar material, with regard to flexibility, for example silicon rubber or another elastomer. The stiff part of the rings consists of any rigid material, such as titanium or alloyed titanium, clothed in a thick silicon sheath.
The elastic part and the rigid part of the rings may be combined together by any suitable means: encapsulation of both ends; keeping them together with a common sheath (in addition to the cloth sheath) for example of silicon; welding or gluing of the compliant part to the ends of the rigid part, the latter being completely covered with a layer of the same material which the elastic part is made of.
To comply with the morphological differences between the natural annuli which are to be reconstructed, the rigi part of the rings of this invention will be provided in several different sizes. During the operation, the surgeo will choose, the proper annulus by measuring the distance between the two commissures for the mitral valve, and the distance between the anteroseptal and posteroseptal commissures for the tricuspid valve; he will then choose annulus with the rigid part of the size corresponding to that distance. The measure will be taken with a sizer.