In Vitro Testing and Comparison of Additively Manufactured Polymer Impellers for the CentriMag Blood Pump

Abstract

Additive manufacturing (AM) is an effective tool for accelerating knowledge gain in development processes, as it enables the production of complex prototypes at low cost and with short lead times. In the development of mechanical circulatory support, the use of cheap polymer-based AM techniques for prototype manufacturing allows more design variations to be tested, promoting a better understanding of the respective system and its optimization parameters. Here, we compare four commonly used AM processes for polymers with respect to manufacturing accuracy, surface roughness, and shape fidelity in an aqueous environment. Impeller replicas of the CentriMag blood pump were manufactured with each process and integrated into original pump housings. The assemblies were tested for hydraulic properties and hemolysis in reference to the commercially available pump. Computational fluid dynamic simulations were carried out to support the transfer of the results to other applications. In hydraulic testing, the deviation in pressure head and motor current of all additively manufactured replicas from the reference pump remained below 2% over the entire operating range of the pump. In contrast, significant deviations of up to 620% were observed in hemolysis testing. Only the replicas produced by stereolithography showed a nonsignificant deviation from the reference pump, which we attribute to the low surface roughness of parts manufactured thereby. The results suggest that there is a flow-dependent threshold of roughness above which a surface strongly contributes to cell lysis by promoting a hydraulically rough boundary flow.

In Vitro and In Vivo Feasibility Study for a Portable VV-ECMO and ECCO2R System

“…Again, the prototype status of the oxygenator may have caused a significant increase in hemolysis, because the entire casing was printed. Recently, Petersdorff-Campen et al [34] showed an increase in hemolysis in printed blood pumps of 620%, which may explain our results. Further, the higher resistance to flow and the hence increased pump performance may have caused hemolysis.…”

Hemodynamic investigation and in vitro evaluation of a novel mixed‐flow blood pump

“…After 6 h of in vitro hemolysis testing by using a 3D printed pump, the average NIH was 0.0079 ± 0.0039 g/100 L ( n = 6). As Von Petersdorff‐Campen et al 39 reported, the surface roughness appeared to have a substantial influence on hemolysis results. Therefore, the NIH value will be preferable when the machining pump with smaller surface roughness comes into use.…”

Mechanical stress‐induced hemolysis of bovine blood is donor‐dependent

“…All hemolysis tests were performed with blood flow rate of 5.0 L/min at pump rotating speed of 4000 rpm and differential pressure (ΔP) of around 350 mm Hg. The “ECMO‐like operation” was adopted to generate higher hemolysis within the same time compared to that “VAD‐like operation” 14 . The portions of the reservoir and Tygon tubing were placed in a temperature‐controlled water bath at 37 ± 1°C.…”