Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Having rigid or semirigid pivoting occluder
Patent
1993-09-13
1995-04-11
Green, Randall L.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Having rigid or semirigid pivoting occluder
137527, A61F 224, F16K 1500
Patent
active
054053820
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ENGINEERING
This invention relates to medical engineering and, more specifically, to a cardiac valve prosthesis.
REVIEW OF THE PRIOR ART
Known in the prior art (Ref. US, A, 4276658) is a cardiac valve prosthesis comprising a circular body accomodating a locking element made in the form of two pivotable folds, each of which has a surface facing the direct blood flow, a surface facing the reverse blood flow, and a side surface coming to contact with the internal surface of the circular valve body, as well as means for fixation of said folds inside the circular valve body, which means include recesses having a surface of revolution formed on the internal surface of the body and projections on each of said folds whose side surface reproduces that of the recesses. Said means for positioning the folds inside the circular valve body enable the folds to pivot from a valve closure position to a valve opening position and vice versa around axes extending in parallel to the plane in which lies the parting line of the folds.
However, the art-known cardiac valve prosthesis suffers from insufficient reliability, since the surface area over which said fold positioning means inside the circular valve body (recess-projection surface contact area) comes to contact is small and, as a result, the wear-out of the contacting surfaces has a localized nature and, consequently, an increased surface wear-out is possible, while great local build-ups of stress concentrations in the prosthesis material are conducive to premature failure of the cardiac valve prosthesis.
Equally known in the prior art is a cardiac valve prosthesis (Ref. US, A, 4274437) comprising a circular body accomodating a locking element realized in the form of two folds pivotably rotatable in relation to the body, each of which folds has a surface facing the direct blood flow, a surface facing the reverse blood flow, a junction surface with the second fold, and a side surface coming to contact with the internal surface of said circular valve body, as well as means for positioning said folds positioning recess inside said circular valve body. The latter comprises a recess formed all along the entire circumferential length of its internal :surface, and projections formed in the form of bodies of revolution protruding from each of said folds. Said fold positioning means inside the circular valve body enable the folds to pivotably turn from a valve closure position to a valve opening position and vice versa around axes running in parallel to the plane in which the folds join one another, as well as to revolve around the central axis of the prosthesis.
Nevertheless, although the latter cardiac valve prosthesis features a better reliability, since the wear-out of the recess formed in the circular valve body as the folds revolve around the central axis of the prosthesis is uniformly distributed all along the entire circumferential length of the internal surface of the body, yet there exists a possibility for an increased local wear-out and for a collapse of the contacting surfaces of the projections on the folds coming to contact over a small contact surface area, whereby the service life of the prosthesis is shortened.
BRIEF DESCRIPTION OF THE SUBSTANCE OF THE INVENTION
The present invention seeks to solve the problem of conceiving such a cardiac valve prosthesis comprising such a folds-to-body positioning assembly in which the surface area of the contacting surfaces of the folds and body would be as large as possible, while preserving the freedom of the folds to freely revolve within the valve body, since these advantageous features would permit to prevent the formation of local wear-out zones and, consequently, to improve reliability of the cardiac valve prosthesis in operation.
The above-formulated problem is solved by using the following approach: in a cardiac valve prosthesis comprising a circular valve body accomodating a locking element realized in the form of two pivotable folds capable of rotating in relation to said valve body, each of which fo
REFERENCES:
patent: 4274437 (1981-06-01), Watts
patent: 4276658 (1981-07-01), Hanson
patent: 4443894 (1984-04-01), Klawitter
patent: 4451937 (1984-06-01), Klawitter
patent: 4488318 (1984-12-01), Kaster
patent: 4676789 (1987-06-01), Sorensen et al.
Evdokimov Sergei V.
Kukolnikov Vladimir K.
Melnikov Alexandr P.
Green Randall L.
Jones Mary Beth D.
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