Importance of the hematocrit as a risk factor in cerebral infarction.

The relationship between the indicence of cerebral infarction and the hematocrit was studied using 432 consecutive autopsied patients with the average age of 77.1 years. The incidence of cerebral infraction was higher in patients with hematocrit values of more than 46%, (the average in younger adult subjects). The increase in the frequency of cerebral infarction with high hematocrit values was more conspicuous in patients with severe cerebral atherosclerosis than in those with slight cerebral atherosclerosis. High blood pressure per se did not influence the relationship between the hematocrit value and the incidence of cerebral infarction. With hematocrit values of more than 41%, cerebral infarction occurred more frequently in patients over 78 years of age than in the younger patients, but the difference was not significant statistically. High hematocrit values are associated with a higher risk of cerebral infarction in deep subcortical structures of the brain than for cartical infarctions. The pathogenetic and preventive implications of these results are discussed in the light of blood rheology.