The particle image velocimetry technique was used to study the shear field across a transparent mechanical heart valve model in one cardiac cycle. Shear stress was continuously increased until peak systole and high turbulent stress was observed at the orifice of the central channel and also around the occluder trailing tips. The peak Reynolds shear stress was up to 500 IN /m(2) at peak systole, which was higher than the normal threshold for hemolysis.
