| 摘要 |
<p>Heart valves, particularly those having two identical leaflets, are shown which utilize improved pivot arrangements that create prompt response to flow reversal and minimize impact at the instant of closing. Illustrated are valves having pairs of leaflets that can assume an orientation in the fully open position that is precisely parallel to the centerline of the passageway, yet which will promptly respond upon blood flow reversal and quickly close to prevent substantial regurgitation. The ability of the leaflets to assume a precisely parallel or low energy position in the bloodstream reduces pressure drop across the valve and results in improved flow characteristics. Prompt closing movement pivoting from a parallel position is effected by creating a camming action adjacent the upstream edges of the leaflets while positively guiding the overall path of leaflet translation and rotation by interengagement at other locations spaced from the upstream edges. The pivot arrangements are particularly effective to positively guide the leaflets to assure effective closing movement regardless of momentary deviations in the dynamics of the reverse flow of blood through the valve.</p> |
