Heparin Concentrations Correlated To The Activated Whole Blood Clotting Time (Act) During Extracorporeal Circulation

Abstract

Heparin levels and ACT were followed during open heart surgery in lo patients. Heparin was assayed by an amidolytic method using substrate S-2222. ACT was determined with an automated method using celite and glass beads as activators of coagulation. Neither the hemodilution nor the depletion of platelets observed during extracorporeal circulation seemed to influence the ACT. An excellent correlation between the ACT and the actual heparin level was found in each patient with coefficients of correlation ranging from 0.73 – 0.97. A slightly better correlation was noticed for values of ACT below 600 seconds. It was concluded that the ACT is a valuable and reliable tool in control of heparinisation during open heart surgery.