Since the use of continuous flow blood pumps as ventricular assist devices is standard, the problems with haemolysis have increased. It is mainly induced by shear stress affecting the erythrocyte membrane. There are many investigations about haemolysis in laminar and turbulent blood flow. The results defined as threshold levels for the damage of erythrocytes depend on the exposure time of the shear stress, but they are very different, depending on the used experimental methods or the calculation strategy. Here, the results are resumed and shown in curves. Different models for the calculation of the strengths of erythrocytes are discussed. There are few results reported about tests of haemolysis in blood pumps, but some theoretical approaches for the design of continuous flow blood pumps according to low haemolysis have been investigated within the last years.

Since the first use of a ventricular assist device in 1963 many extracorporeal and implantable pulsatile blood pumps have been developed. After the invention of continuous flow blood pumps the implantable pulsatile pumps are not available anymore. The new rotary pumps spend a better quality of life because many of the patients can go home. Nevertheless, the extracorporeal pulsatile pumps have some advantages. They are low-cost systems, produce less haemolysis and heart-recovery can be tested easily. Pump failure is easy to realize because the pumps can be observed visually. Pump exchange can be done easily without any chirurgic surgery. As volume displacement pumps they can produce high blood pressure, so they are the only ones suitable for pediatric patients. Therefore, they are indispensable for clinical use today and in the future. In this work, nearly all pulsatile blood pumps used in clinical life are described.

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