In vitro comparison of the hemocompatibility of two centrifugal left ventricular assist devices

Shear stress from left ventricular assist devices induces von Willebrand factor degradation and platelet dysfunction, leading to nonsurgical bleeding. We characterized the hemostatic changes induced by 2 centrifugal left ventricular assist devices, the HeartMate 3 (Abbott Inc, Chicago, Ill) and the EVAHEART (Evaheart Inc, Houston, Tex), for comparison.

Whole blood from 8 healthy volunteers was used ex vivo. Blood from the same donor was used for 6 hours of circulation in a miniature mock-loop system consisting of 2 identical extracorporeal circuits to compare the following experimental settings: (1) optimal revolutions per minute (rpm) for the HeartMate 3 (n = 4; 5000 rpm) and the EVAHEART (n = 4; 2500 rpm) and (2) equal rpm (3000 rpm for the HeartMate 3 and EVAHEART, n = 4 vs n = 4). For both settings, blood flow was adjusted to 1 mock-loop filling volume per minute (HeartMate 3 = 82 mL/min, EVAHEART = 100 mL/min). A panel of coagulation markers was analyzed to investigate hemostatic changes.

The free plasma hemoglobin concentration was significantly lower in the EVAHEART compared with the HeartMate 3 after 6 hours of mock-loop circulation under both settings (optimal: 37 ± 31 vs 503 ± 173 mg/dL, P < .0001; equal: 27 ± 4 vs 139 ± 135 mg/dL, P = .024). Loss of von Willebrand factor high-molecular-weight multimers occurred in both left ventricular assist devices and settings, but the von Willebrand factor:activity/von Willebrand factor:antigen ratio after 6 hours was significantly lower in optimal settings for the HeartMate 3 (P = .009). The thrombin-antithrombin complex level was significantly lower with the EVAHEART for both settings (P < .0001).

The EVAHEART left ventricular assist device caused less hemolysis, resulted in lower coagulation activation, and provided better preservation of von Willebrand factor functional activity compared with the HeartMate 3 device. These findings prove that left ventricular assist device design plays a major role in minimizing blood damage during left ventricular assist device support.