Mean velocities and Reynolds stress measurements around the valves in the Penn State LVAD

A laser Doppler anemometer (LDA) was used to measure two components of velocity at eight locations around the Bjork-Shiley monostrut artificial valves in a plexiglass model of the Penn State 70 cc electric left ventricular assist device (LVAD). The model was filled with a blood analog fluid which matched the kinematic viscosity of blood. The model was connected to a mock circulatory loop in order to generate physiologic conditions. Two hundred and fifty velocity realizations were obtained during six time windows in the regurgitant phase of the flow cycle. These data were then processed, and the mean velocities and Reynolds turbulent stresses were calculated. The results reveal that a significant regurgitant jet occurs in the minor orifice of both the mitral and aortic valves. The strength of the jet is large enough for hemolysis and blood damage to occur