Evaluation of in vitro hemolysis and platelet activation of a newly developed maglev LVAD and two clinically used LVADs with human blood

Abstract

In vitro hemolysis testing remains one of the most important performance measures to judge the hemocompatibility of a left ventricular assist device (LVAD). Clinically relevant operating conditions and appropriate testing blood are essential to infer in vitro data for potential clinical use. This in vitro study was carried out to evaluate and compare the hemolytic performance of a newly developed magnetically levitated (maglev) LVAD (CH‐VAD) with two clinically used LVADs (HVAD and HeartMate II (HMII)) using fresh human blood. A small volume (~300 mL) in vitro circulating flow loop was constructed with a LVAD generated flow of 4.5 L/min at the nominal or reported clinical operating speed for each LVAD. The blood was circulated in the loop for 4 hours with samples drawn at baseline and hourly. Plasma‐free hemoglobin (PFH) concentrations in the hourly blood samples were determined with spectrophotometry. Normalized index of hemolysis (NIH) was calculated to compare the hemolytic performance of the CH‐VAD and the two reference LVADs. Platelet activation was measured with flow cytometry. The experimental test for each device was repeated at least 7 times. The data from this study showed that all the three LVADs generated very low hemolysis (NIH <0.01 g/100 L). The CH‐VAD was found to have a significantly lower NIH value (0.00135 ± 0.00032 g/100 L) compared to the HVAD (0.00525 ± 0.00183 g/100 L) and the HMII (0.00583 ± 0.00182 g/100 L). No statistically significant difference in device‐generated hemolysis was found between the HVAD and the HMII. The level of platelet activation induced by the CH‐VAD is significantly lower than those by the HVAD and the HMII. The data suggest that the shear‐induced hemolysis and platelet activation of the CH‐VAD are acceptable relative to the two LVADs currently in clinical use.

Circulatory loop design and components introduce artifacts impacting in vitro evaluation of ventricular assist device thrombogenicity: A call for caution

“…Many groups normally do not explicitly mention the consideration of avoiding loop‐induced blood damage and they might accidently introduce those components. For instance, a standard loop similar to ASTM F 1841 set up by Berk et al to evaluate LVAD hemolysis utilized two reducer connectors (similar to a nozzle) for the installation of a clamp on flow probe, which was studied and illustrated to induce hemolysis by FDA …”

Prediction of mechanical hemolysis in medical devices via a Lagrangian strain‐based multiscale model

“…The groups of authors recently measured the NIH in this device when the impeller speed is 9200 rpm and the flow rate is 4.5 LPM. 69 The loop used for measuring NIH of the HM II was the same as the CentriMag described previously. More details about this experiment can be found in.…”

“…More details about this experiment can be found in. 69 The computational grid used for this test case is displayed in Figure 20B. Mesh was refined near walls and in the region with complex geometries.…”

Durable mechanical circulatory support across the Asia-Pacific region

“…The CH-VAD (CH Biomedical Inc, Suzhou, China), a fully magnetically suspended LVAD system, has been introduced with an in vitro study that shows shear-induced hemolysis and platelet activation acceptable relative to 2 other LVADs that are not fully magnetically levitated. 8 The first implantation of CH-VAD in a man was performed on June 26, 2017 at Fu Wai Hospital, Beijing, China, and the recipient has crossed 3 years' survival. A clinical trial in China commenced in March 2019, and 25 implantations have been performed.…”