Erythrocyte deformability in patients during left ventricular assistance

Abstract

Hemorheologic studies using clinical filtration pressure techniques have suggested that changes in erythrocyte (RBC) deformability occur during left ventricular assist system (LVAS) support. In order to assess whether changes suggested by clinical filtration pressure were associated with alterations in the actual material properties of the membrane complex, micropipette aspiration experiments were performed during NOVACOR LVAS support ranging between 28 and 126 days in four patients. The micropipette aspiration method provides a direct measurement of the surface shear elastic modulus μ of the RBC membrane complex. The modulus consistently fell within the range reported for normals, and no apparent trend with time was evident. In one instance, however, an abnormal spike in μ, which paralleled clinical filtration data, coincided with symptoms of a transient neurologic event. For the LVAS patients studied, clinical abnormalities in hemorheology as indicated by filtration were not attributed to changes in μ.