Fåhraeus Award Lecture

Abstract

The resistance to blood flow is equal to the product of vascular hindrance and blood viscosity, which is a function of hematocrit, plasma viscosity, red cell aggregation and red cell deformability. These hemorheo1ogical components can be assessed by using a systematic approach. Data obtained from patients with hematological disorders (polycythemia, multiple myeloma, sialic acid deficiency and sickle cell disease) indicate that abnormalities in one rheological component may be associated with either coexisting abnormalities or compensatory changes in other components. Correlation with in vivo hemodynamic functions has shown that hemorheological abnormalities may affect flow resistance and oxygen transport and that a normal cardiovascular system has the capacity to compensate for these disturbances, e.g., by vasodilation. Hemorheological abnormalities are also found to exist in cardiovascular diseases (e.g., myocardial infarction, hypertension and peripheral vascular disease). Although these abnormalities are milder than those found in hematological disorders, their pathophysiological significance is enhanced by the mutual amplification, rather than compensation, of the disturbances in hemorheological and cardiovascular functions. Improvement of blood rheology is a promising approach in the treatment of circulatory diseases.