Lange U, Olschewski A, Nowak G, Bucha E
Hamostaseologie. 2005 Aug;25(3):293-300. doi: 10.1267/hämo05030293.
The ecarin chromogenic assay (ECA) was developed for quantitative determination of direct thrombin inhibitors. As a further development of the ecarin clotting time (ECT), the ECA is based on the same principle, the activation of prothrombin by ecarin a snake venom from Echis carinatus. In the ECA the prothrombin activation products meizothrombin and meizothrombin-desF1 cleave a chromogenic substrate, whereas in the clotting assay ECT plasma fibrinogen is converted to fibrin. The activity of meizothrombin/meizothrombin-desF1 is inhibited in a concentration-dependent fashion by direct thrombin inhibitors. The ECA can be used as ECA-H for quantitative determination of hirudin and as ECA-T for determination of synthetic thrombin inhibitors. As shown for hirudin, argatroban and melagatran, the ECA turned out as a very precise and sensitive method, which combines the advantages of ECT with those of chromogenic assays. In ECA very low interindividual variations were found compared to aPTT and even ECT. The ECA is independent of the variations of the coagulation variables prothrombin and fibrinogen.
蛇毒凝血酶显色测定法（ECA）是为定量测定直接凝血酶抑制剂而开发的。作为蛇毒凝血酶凝结时间（ECT）的进一步发展，ECA基于相同原理，即由锯鳞蝰蛇毒中的蛇毒凝血酶激活凝血酶原。在ECA中，凝血酶原激活产物中凝血酶和中凝血酶-desF1裂解一种显色底物，而在凝血测定ECT中，血浆纤维蛋白原转化为纤维蛋白。直接凝血酶抑制剂以浓度依赖方式抑制中凝血酶/中凝血酶-desF1的活性。ECA可作为ECA-H用于水蛭素的定量测定，作为ECA-T用于合成凝血酶抑制剂的测定。如水蛭素、阿加曲班和美拉加群所示，ECA是一种非常精确和灵敏的方法，它结合了ECT和显色测定法的优点。与活化部分凝血活酶时间（aPTT）甚至ECT相比，在ECA中发现个体间差异非常小。ECA不受凝血变量凝血酶原和纤维蛋白原变化的影响。
