| 摘要 |
A bileaflet prosthetic valve has leaflet pivots symmetrically or centrically located, thereby providing a central opening about twice the size of the two lateral openings. The valve opens from the center outward to provide nonturbulent central flow. The laminar leaflets are curved in cross-section so that the downstream edges of the leaflets are closer to the centerline of the cylindrical support ring when the leaflets are in an opened configuration. This position disposes the leaflets to favor valve closure when reverse flow of blood occurs. As the leaflets move toward a closed position, upstream edges of the leaflets begin to close the lateral openings, but this movement is opposed by blood flowing through these openings thereby providing a force to decelerate the leaflets and cushion their final closing. When the valve is fully closed, a single point of contact between the upstream edge of each leaflet and the support ring leaves a small gap between the support ring and the rest of the upstream edge and prevents the downstream edges from touching each other when they close the central opening.
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