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

Abstract

Objectives: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Keywords: EVAHEART; HeartMate 3; Left ventricular assist device; circulatory mock-loop; haemolysis; hemocompatibility.