Extracorporeal circuit heparinization in selective low density lipoprotein apheresis: changes in patient hemostasis and low molecular weight heparin benefit.

Treatment by low density lipoprotein (LDL) apheresis using dextran sulfate columns (DSC) leads to hemostasis alterations with prolonged activated partial thromboplastin time (APTT) of more than 120 seconds. In order to explain this hypocoagulability, we studied hemostasis parameters both in patients and in the extracorporeal circulation (ECC). Hemostasis changes are first related to unfractionated heparin (UFH)--needed to avoid circuit coagulation--which leads to high residual heparinemia in the patient (more than 3 times the recommended level for therapeutic use). Second, the hypocoagulability is induced by a coagulation factor decrease (primarily factors V, VIII, and X) mainly due to an adsorption mechanism on dextran sulfate. Studies on samples from column inflow, outflow, and eluate confirm this mechanism. Low molecular weight heparin (LMWH) can be used in LDL apheresis on DSC without major changes in lipid removal or coagulation factors compared to UFH. The benefit of using LMWH is to reduce residual heparinemia into the therapeutic range.