1987 Volume 9 Issue 1 Pages 54-61
Whole blood viscosity (WBV) and its major determinants (hematocrit (Ht), plasma viscosity (PV) and indirect deformability of red blood cells (RD-Index)) were measured in 40 normal subjects and 325 cases with cerebral infarction (91 cases with perforator thrombosis, 152 with cortical artery thrombosis and 82 with cerebral embolism). WBV and PV were measured with a cone-plate viscometer (Tokyo Keiki Co.) at the shear rates of 75.5 and 377.5/sec. These rheologic factors were analysed in relation to age, subtypes of cerebral infarction and the time elapsed from onset (stage).
PV was higher than normal in all but one subgroup irrespective of age and stage. In the group of perforator thrombosis, patients under the age of 60 years old showed an increased RD-Inedx (high RD-Index indicates poor RBC deformability) during both acute (within Day 7) and subacute (after Day 8) stages, but Ht was increased only in acute stage. In patients over 60 years old of the same group, however, RD-Index was increased only in acute stage, and Ht was not higher than normal throughout the course.
RD-Indices in patients with cortical artery thrombosis were not increased even when they were divided into subgroups by age and stage. Ht was higher than normal controls in acute stage of the younger age group (<60 years old). In cerebral embolism, no significant abnormalities of these rheologic factors were detected except for PV.
When the patients with thrombotic major cerebral artery occlusion (internal carotid and middle cerebral artery trunk, 208 cases) were divided into two subgroups by the grade of availability of transcortical collateral circulation, Ht in patients with poor collaterals was significantly higher in acute stage than normal and other subgroups. RD-Index in this group also tended to be higher in acute stage than others, but the difference was significant only in subacute stage.
In contrast, patients with thrombotic occlusion having good collaterals and those with embolic occlusion showed no abnomal values of rheologic factors except for an increased PV.
In summary, abnormalities of blood rheologic factors were most frequently found and most apparent in patients with perforator thrombosis, followed by those with thrombotic major cerebral artery occlusion and embolic occlusion, respectively. From the above results, it is suggested that these rheologic factors may play one of the important roles in promoting the occurrence of thrombotic cerebral infarction, especially in regions of perforating arteries. Impairment of RBC deformability might have been present before the onset of stroke, and an increment of Ht by any reasons may have induced a circulatory disturbance in such small vessels as perforating arteries.
