High Blood Viscosity Syndrome in Cerebral Infarction

Abstract

Determinations of whole blood viscosity by means of a cone plate viscometer at 37°C and at shear rates of 212, 42, 21 and 11 sec^-1 were done in 50 patients with recent cerebral infarction of the carotid system, and the values compared to a control group of 50 patients of the same age. In stroke patients a statistically significant elevation of blood viscosity over the whole range of shear rates was demonstrated, more obviously significant at low shear rates (P < 0.0001) such as occur in small vessels. Since the mean hematocrit levels of both groups were in the normal range, it was considered that hematocrit values estimated from peripheral blood do not necessarily give accurate information about viscosity levels existing at the same time. In cases of severe cerebral infarction without angiographically demonstrable stenotic or obstructive lesions, it was suggested that high blood viscosity impairs hemodynamic conditions in the cerebral microvasculature in addition to narrow arteriosclerotic vessels, changes in flow velocity gradients and insufficient collateral circulation.