On the mechanical blood trauma: effect of turbulence

Mechanical blood trauma is still one of the major obstacles in the development of cardiovascular devices. The mechanisms of this blood damage are heterogeneous and are not completely identified. Experimental and computational studies were performed to elucidate the role of turbulent stresses in hemolysis. For the experimental study suspensions of bovine red blood cells (RBCs) in saline or in dextran solution were driven through a closed circulating loop by a centrifugal pump. A small capillary tube with the inner diameter of 1 mm and the length of 50 mm was incorporated into loop with tapered connectors. It was shown that, at the same wall shear stress, the level of hemolysis is significantly higher under turbulent flow conditions than laminar flow conditions. This demonstrated that turbulent stresses contribute strongly to blood trauma. These results concurred with predicted hemolysis by computational fluid dynamics (CFD) modeling of the same blood flow conditions.