Mock circulation loop to investigate hemolysis in a pulsatile total artificial heart

Hemocompatibility of blood pumps is a crucial parameter that has to be ensured prior to in vivo testing. In contrast to rotary blood pumps, a standard for testing a pulsatile total artificial heart (TAH) has not yet been established. Therefore, a new mock circulation loop was designed to investigate hemolysis in the left ventricle of the ReinHeart TAH. Its main features are a high hemocompatibility, physiological conditions, a low priming volume, and the conduction of blood through a closed tubing system. The mock circulation loop consists of a noninvasive pressure chamber, an aortic compliance chamber, and an atrium directly connected to the ventricle. As a control pump, the clinically approved Medos-HIA ventricular assist device (VAD) was used. The pumps were operated at 120 beats per minute with an aortic pressure of 120 to 80 mm Hg and a mean atrial pressure of 10 mm Hg, generating an output flow of about 5 L/min. Heparinized porcine blood was used. A series of six identical tests were performed. A test method was established that is comparable to ASTM F 1841, which is standard practice for the assessment of hemolysis in continuous-flow blood pumps. The average normalized index of hemolysis (NIH) values of the VAD and the ReinHeart TAH were 0.018 g/100 L and 0.03 g/100 L, respectively. The standard deviation of the NIH was 0.0033 for the VAD and 0.0034 for the TAH. Furthermore, a single test with a BPX-80 Bio-Pump was performed to verify that the hemolysis induced by the mock circulation loop was negligible. The performed tests showed a good reproducibility and statistical significance. The mock circulation loop and test protocol developed in this study are valid methods to investigate the hemolysis induced by a pulsatile blood pump.