In vivo rheologic effects of lipid apheresis techniques: comparison of dextran sulfate LDL adsorption and heparin induced LDL precipitation. The effects of two different LDL apheresis techniques, heparin-induced LDL precipitation (HELP) and dextran sulfate LDL adsorption (DSA), were compared in six patients with familial hypercholesterolemia. Total and LDL cholesterol were effectively lowered with both techniques. The reduction of serum triglycerides was more pronounced with DSA, whereas the reduction of HDL cholesterol was more pronounced with HELP. Single sessions using both techniques immediately reduced whole blood and plasma viscosity, as well as erythrocyte aggregation. Serum fibrinogen decreased by 62% (HELP) and 11% (DSA). Maintenance lipid apheresis administered 1 time per week resulted in a sustained reduction of total and LDL cholesterol and was associated with a sustained improvement in blood flow properties. Data suggest that besides serum fibrinogen, serum lipoproteins may adversely effect the rheologic characteristics of blood. 