Lactic Dehydrogenase in the In Vitro Evaluation of Hemolytic Properties of Ventricular Assist Device

Ventricular assist devices (VADs) can effectively improve the survival rate of patients with end-stage heart failure, but the hemolytic complications induced by long-time VAD support have received wide attention recently. The conventional evaluation method of the hemolytic properties of VADs by the indicator of plasma free hemoglobin (PFH) concentration is used but not sensitive enough to meet the needs of the actual examinations. In this study, an experimental method was applied for the evaluation of the injuries and damages caused by VADs to erythrocytes by both indicators of PFH and lactic dehydrogenase (LDH) in the in vitro hemolysis assay of VADs. The changes of LDH and PFH concentrations in plasma with the shear stress and the exposure time under a fixed shear stress were measured and analyzed to investigate the sensitivity and accuracy of the evaluation of erythrocyte damage by LDH. Furthermore, through 24 h in vitro hemolysis tests, the changes of LDH and PFH concentrations in blood samples were measured in combination with the microscopic histological changes and ultrastructural changes of erythrocytes, to assess the possibility of LDH evaluating the hemolysis of VADs. The changes of the concentration of LDH were more sensitive than those of PFH to different shear stress and exposure times, especially lower stress. Meanwhile, in the 24 h in vitro hemolysis assay, the PFH concentration in the blood samples showed no significant changes in the first 8 h, while the LDH concentration increased significantly in the first 3 h, which was consistent with the morphological changes of erythrocytes. Compared with the changes of the PFH concentration, the LDH concentration is sensitive to the damage of erythrocytes caused by VADs. It was considered that LDH could be applied as an additional indicator in the evaluation of erythrocyte damage and hemolytic properties of VADs in combination with the normalized index of hemolysis, for the more accurate assessment of the blood compatibility of VADs.