English to Italian Medical Medical: Cardiology Mechanical heart valves,

Part of a description of a mechanical heart valve:
"If the leaflets are not fully open and flow reverses, fluid drag will force the leaflets to translate toward the inflow edge of the sockets. In this situation, the leaflet leading edge engages the closing ramp in the pivot creating a remote center of rotation for the leaflet and causing the leaflet to begin closing immediately. Once the swing toward closure starts, fluid lift takes over to produce rapid closure with a maximum angular excursion of 50°. Because of the closure ramp, this valve must close with backflow regardless of the opening angle.

The leaflet translation and rotation, together with the smooth curvature of the pivot, act to facilitate pivot flushing throughout the cardiac cycle. The limited angular excursion and rapid closure response achieve reduced closure regurgitation, thus improving fluid dynamic performance."