(237r) Following the Hemo-Rheology of Cardiac Surgery Patients - RBC Aggregation and Blood Viscoelasticity

We investigated blood rheology and blood microstructure following cardiac surgery with cardio-pulmonary bypass (CPB). We examined blood viscoelasticity and RBC aggregate size in the pre-surgery disease state, post-surgery state and long-term recovery state of cardiac surgical patients. Within a week following surgery, the patient RBC concentration was significantly lower due to CPB. Despite lower RBC concentration, the RBC aggregate shape became larger and more rounded, which is correlated to the elevated plasma fibrinogen related to systemic inflammatory response. During the same period, the hematocrit-adjusted low shear rate viscosity increased significantly, as did the yield stress, indicating more solid-like behavior for blood. Six months to one year later, all the physical and biochemical properties measured returned to baseline.