Hemolysis in a continuous-flow ventricular assist device with/without chamfer:

Ventricular assist device has been increasingly used in the treatment of end-stage heart failure, with a high incidence of hemolysis in clinical use, which is a serious problem to be solved. In this study, a complete set of continuous-flow ventricular assist device in vitro test platform for hydraulic performance and hemolysis was established. A self-developed continuous-flow ventricular assist device was employed, with the impeller being chamfered or unchamfered, respectively, to undergo the hydraulic performance and in vitro hemolysis tests, using computational fluid dynamics and a rheometer to investigate the influences of the shear stress on hemolysis. Computational fluid dynamics results showed that the shear stress of continuous-flow ventricular assist device with chamfered impeller was significantly decreased; as a result, the normalized index of hemolysis of the chamfered was reduced, demonstrating that lowering the shear stress of the impeller could significantly reduce hemolysis. Moreover, it was further confirmed by a fixed shear stress test. When the shear stress was greater than 100 Pa, the hemolytic effects were increased significantly. In standard operating conditions, lowering the impeller's shear stress to less than 100 Pa could effectively reduce the hemolytic effects of ventricular assist device.