Hemorheological changes dependent on the time from the onset of ischemic stroke

This work aimed at estimation and comparison of chosen rheological parameters of blood in two group of patients in acute and remote stroke phase. The analysis included the values of shear stress, plasma viscosity, relative blood viscosity, hematocrit value and the parameters of rheological Quemada model of blood flow. The main two groups (30 persons each) consisted of patients after cerebral ischemic episode, remaining under permanent medical control, the first one in the acute and the second in the remote phase. The reference group (20 persons) included the patients who never suffered from any circulatory system disorders and who did not take any drugs affecting the hemorheological parameters. The results suggest that after a distinct increase of most of the hemorheological parameters in the acute stroke phase, a gradual improvement was observed in the remote phase. Since in the latter group the plasma viscosity remained on elevated level, we suggest a creation of a specific feedback mechanism leading to a decrease of the blood viscosity and thus better perfusion of brain. The analysis of Quemada model parameters indicates that the decrease of blood viscosity may result from the increased red cell deformability.