Effect of fibrin and fibrinogen proteolysis products on clot physical properties

¹ Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri

Clot formation in the presence of plasmin-stable proteolysis products of fibrinogen and fibrin was studied by thromboelastography and by a modified light-scattering method. Thromboelastography demonstrated that both types of proteolysis products lengthened the "r" and "k" values and decreased "ma" values; these findings were interpreted as demonstrating delayed fibrin formation and reduced clot tensile strength. Light-scattering measurements demonstrated that both sets of products inhibited fibrin polymerization rates. Neither qualitative nor quantitative differences were detected between the actions of fibrin or fibrinogen proteolysis products, and the degree of alteration in functional clotting parameters and in clot tensile strength was proportional to proteolysis product concentration. Platelet function tests, including clot retraction tests, microscopic and turbidometric measurement of thrombin, and ADP-induced platelet aggregation, were uninfluenced by plasmin-stable proteolysis products. Most conventional plasma fibrinogen assays yielded artifactually low values when the plasma contained proteolysis products, but the accuracy of a modified Ratnoff and Menzie procedure was unaffected in these circumstances. A rapid immunological assay (Fi test) also proved satisfactory.

Key Words: defective fibrin polymerization • fibrin proteolysis • clot tensile strength • thromboelastography • delayed polymerization • platelet aggregation • coagulation defect

Submitted on January 18, 1965