Effect of low-dose subcutaneous heparin on whole-blood viscosity

The change in blood-viscosity at low shear-rates (0.77 s-1 and 2-62 s-1 was measured in eighteen normal subjects and postoperatively in sixteen patients after administration of 5000 I.U. of subcutaneous heparin. In both groups there was a significant decrease in the mean blood-viscosity 4 to 6 hours after the injection of heparin. This fall in blood-viscosity may be involved in the prophylactic effect of low-dose subcutaneous heparin in preventing venous thrombosis.