Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Heart valve – Having rigid or semirigid pivoting occluder
Reexamination Certificate
1999-05-12
2001-03-27
Milano, Michael (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Heart valve
Having rigid or semirigid pivoting occluder
C623S002280
Reexamination Certificate
active
06206918
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to heart valve prostheses and, in particular, to an improved pivot design for the pivotable leaflet occluders.
BACKGROUND OF THE INVENTION
A variety of heart valve prostheses have been developed for use in hearts, such as human or animal hearts. The typical heart value prosthesis generally includes a main body portion having an annular shape and a central passage for blood flow. One or more leaflet occluders are mounted to the annular body for pivotable movement within the central passage. Such heart valve assemblies operate hemodynamically in conjunction with the pumping action of the heart for effective replacement of a defective natural heart valve.
A common heart valve construction is the bi-leaflet design in which two leaflet occluders are pivotably mounted in the annular body in an opposed relationship. The leaflet occluders are mounted such that when the heart valve is closed, each leaflet occluder covers approximately half of the valve opening or passage. Typically, each leaflet occluder is generally semi-circular in shape and includes a rounded exterior which engages an inner surface of the main body that defines the central passage. Each leaflet occluder also includes a generally linear edge portion designed to move proximate the linear edge portion of the opposing leaflet occluder when the valve is closed. Each leaflet occluder is mounted for pivotable movement about an axis disposed generally parallel with the linear edge.
In operation, as blood pressure rises in response to heart contraction, the leaflet occluders are pivoted from a closed position to an open position. In the open position, blood flows past the leaflet occluders through the heart valve passage. When the heart contraction is complete, however, the blood tends to flow in the opposite direction in response to pressure in the aorta. This causes the leaflet occluders to close and thereby maintain a pressure in the arterial system. Effectively, this type of heart valve prosthesis operates in substantially the same manner as a natural human heart valve.
Conventional leaflet occluders include opposing tabs or ears that are received in corresponding recesses formed in the interior surface defining the flow passage. Each pair of opposed recesses constrain the leaflet occluder mounted therein, and the walls of the recesses serve as stops to limit the pivoting motion of the leaflet occluders at closed and open positions. Exemplary prior art designs are illustrated and described in such patents as Hanson et al., U.S. Pat. No. 4,276,658, Bokros, U.S. Pat. No. 4,689,046, and Campbell, U.S. Pat. No. 5,147,390. Such prior art valves have generally proved to be very reliable, and have a projected life expectancy exceeding that of the patient. However, it is desirable to continually increase or enhance the performance characteristics of heart valve prostheses.
For example, problems can develop because of the design of the recesses for receiving the leaflet occluder ears. In many applications, it is desirable to design recesses with a contour providing at least two stops that act against the leaflet ear to limit the pivotable motion of a given leaflet occluder. By separating the stops that act against the ear, the angle at which the leaflet occluders close and/or open can be better controlled. The Hanson et al. reference and the Bokros reference cited above utilize recesses having narrowed throat regions and expanded outlying regions to provide at least two stops separated by a given distance that act against the leaflet occluder ear to limit a given pivoting motion.
Though such designs provide two stopping surfaces, they are typically limited by wall surfaces that are generally perpendicular to the interior surface that defines the blood flow passage of the heart valve. Such perpendicular surfaces often exist throughout the throat region of the recess and limit the ability of the blood to freely flow through the recessed area. As a result, blood clotting can occur in the vicinity of the pivot recesses.
It would be advantageous to provide a heart valve prosthesis with uniquely designed leaflet occluder pivot recesses able to facilitate better blood flow characteristics while providing stable control of the opening and closing of the leaflet occluders.
SUMMARY OF THE INVENTION
The present invention features a heart valve prosthesis comprising a valve body and a pair of leaflet occluders. The valve body includes an interior surface that defines a central passage for blood flow therethrough. The leaflet occluders are proportioned to be pivotably mounted within the central passage. Each leaflet occluder includes a pair of mounting ears, and the valve body includes a plurality of recesses for receiving the pairs of mounting ears. Each recess is bounded by a base surface and a sidewall. The sidewall defines a narrowed throat region, an upstream expanded region on one side of the throat region, and a downstream expanded region on a generally opposite side of the throat region. The sidewall slopes outwardly from the base surface to form an angle with a central recess axis along the entire length of the sidewall. Thus, there are no surfaces generally perpendicular to the interior surface of the valve body.
According to another aspect of the present invention, a heart valve prosthesis is provided that includes a valve body having an interior surface defining a central passage for conducting blood flow. The heart valve prosthesis also includes at least one leaflet occluder pivotably mounted to the valve body by a pair of pivots. The interior surface that defines the central passage includes at least one pair of recesses to receive the pair of pivots. Each recess is bounded by a continuously sloped sidewall extending between the interior surface and a recess base. Each recess further includes a narrowed throat region disposed such that the continuously sloped sidewall forms at least one pivot stop on each opposing side of the narrowed throat region. The pivot stops cooperate to limit pivotal motion of the at least one leaflet occluder.
According to yet another aspect of the present invention, a method is provided for facilitating blood flow through a prosthetic heart valve. The prosthetic heart valve is of the type including a valve body having an interior surface defining a central passage through which blood flows and a leaflet occluder pivotably mounted in the central passage by a pair of pivot ears. The method includes creating a first recess and a second recess in the interior surface on generally opposite sides of the central passage to receive a pair of pivot ears of an individual leaflet occluder. The method further includes forming each of the first recess and the second recess with a pair of expanded regions separated by a narrower throat region. The method further includes defining the first recess by a first sidewall and the second recess by a second sidewall. Additionally, the sidewalls are oriented at an angle throughout the narrower throat region and the pair of expanded regions to prevent the formation of surfaces that would be generally perpendicular to the interior surface of the valve body.
REFERENCES:
patent: Re. 30507 (1981-02-01), Kaster
patent: 3974854 (1976-08-01), Kurpanek
patent: 4276658 (1981-07-01), Hanson et al.
patent: 4363142 (1982-12-01), Meyer
patent: 4605408 (1986-08-01), Carpentier
patent: 4657545 (1987-04-01), Zibelin
patent: 4689046 (1987-08-01), Bokros
patent: 4692165 (1987-09-01), Bokros
patent: 4979955 (1990-12-01), Smith
patent: 5135538 (1992-08-01), Pawlak et al.
patent: 5147390 (1992-09-01), Campbell
patent: 5192313 (1993-03-01), Budd et al.
patent: 5545216 (1996-08-01), Bokros et al.
patent: 5545487 (1996-08-01), Ishijima et al.
patent: 5554184 (1996-09-01), Machiraju
patent: 5641324 (1997-06-01), Bokros et al.
patent: 5741328 (1998-04-01), Reif
patent: 5814100 (1998-09-01), Carpentier et al.
patent: 31 28 704A (1983-02-01), None
patent: WO97/30658 (1997-08-01), None
Filbioloa, R. S., et al., On The Hemolytic And Thrombo
Campbell Louis A.
Gourley Monti R.
Lyren Philip S.
Milano Michael
Scott Timothy L.
Sulzer Carbomedics Inc.
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