Numerical estimation of blood damage in artificial organs.

The aim of this study was to determine a method for the numerical estimation of blood damage. Normally, human or animal blood is used for in vitro evaluation of lysis by artificial organs. However, blood has some disadvantages: large biological variability and different initial test conditions lead to nonreproducible test results. For that reason, it would be an advantage to have a numerical method for blood damage estimation. This proposed method is based on the calculation of an integrated hemolysis and platelet lysis index along the path line in the flow field of the artificial organ. The time-dependent shear stress related lysis is based on known experimental data. In order to calibrate these data, the method was first applied to blood circulation in the human body. The results showed that the known data overestimate hemolysis by a factor of approximately 25. Next, the method was applied to a standard Björk-Shiley valve. The flow through a valve was simulated with the computational fluid dynamics program FLUENT. The calculation of lysis was added into FLUENT and done automatically. The results showed that the Björk-Shiley valve increased the hemolysis index by 7% if implanted in the human body circulation.