3-COMPONENT LASER-DOPPLER VELOCIMETRY MEASUREMENTS IN THE REGURGITANTFLOW REGION OF A BJORK-SHILEY MONOSTRUT MITRAL-VALVE

Three-dimensional laser Doppler velocimetry measurements were acquired in a mock-circulatory loop proximal to a Bjork-Shiley monostrut valve in the mitral position, and synchronous ensemble-averaging was applie d to form an ''average'' beat. Two axial locations in the regurgitant flow region of the valve (in the minor orifice) were mapped, and maxim um Reynolds shear stresses were calculated. A large spike in regurgita nt flow was noted at the beginning of systole, which may be the squeez e flow phenomenon computed by other researchers. A region of sustained regurgitant flow 50 msec later was the focus of this study. Maximum v elocities of similar to 3.7 mps were noted, and maximum Reynolds shear stresses of similar to 10,000 dyne/cm(2) were calculated. Comparisons were made of two-dimensional (ignoring tangential component) versus t hree-dimensional shear stresses, and, in this case, in regions of high stress, the differences were insignificant. This suggests that the ta ngential component of velocity can probably be ignored in similar meas urements where the tangential velocity is likely to be small.