Myocardial Infarction and Whole‐blood Viscosity

Based on the observation of increased hematocrit levels in patients suffering from acute myocardial infarction, it has been suggested that rheological factors, especially an increased whole‐blood viscosity, have a primary importance for the development of myocardial infarction. For this reason whole‐blood viscosity and related components were measured in 25 patients with acute myocardial infarction within the first 24 hours and on the twenty‐first day after the onset of chest pain. On the first day the hematocrit did not differ significantly from those of a control group of healthy subjects of similar age and of the same sex. The average whole‐blood viscosities were significantly higher in patients with myocardial infarction on the first day. Simultaneously the concentration of plasma fibrinogen and alpha 2 ‐globulin was significantly increased. On the twenty‐first day of the infarction the average hematocrit values and whole‐blood viscosities were significantly decreased. The changes in the rheological properties of blood suggest that an acute injury response is operative in acute myocardial infarction.