Occult fibrin production during surgery in cyanotic congenital heart defects and extracorporeal circulation
Abstract
In 10 patients with complex cyanotic congenital defects detailed coagulation examinations were made at the beginning and end of the extracorporeal circulation after neutralization of heparin by protamine and the results were compared with a control examination, made before general heparinization, after introduction into general anaesthesia. The authors examined the activated period of blood (ACT) by means of testing tubes with a celite activator (Hemochron) as well as the HR-ACT test with a kaolin activator (Medtronic) for comparison of the results.
The authors assessed quantitatively plasma levels of heparin, antithrombin III and fibrinopeptide A which is a sensitive indicator of intravascular coagulation. They assessed also the fibrinogen level and total number of thrombocytes in the blood stream.
The degree of haemodilution was recorded as well as the temperature at the periods of assessment. The values of both ACT test were within the range of values above 420 sees., evaluated according to the authors protocol as adequate for total heparinization during operations under conditions of extracorporeal circulation.
Despite of this heparin levels lower than those recommended in the literature were found, as well as reduced antithrombin III levels during extracorporeal circulation and a rise of fibronopeptide A levels at the end of extracorporeal circulation which suggest latent fibrin production in the patients. Laboratory results were compared with clinical symptoms of post-operation bleeding.
In 50 % patients after surgery signs of increased haemorrhage in the surgical field and from thoracic drains were observed, in two patients the surgical wound had to be revised. Laboratory tests revealed in two patients thrombocjrtopenia after surgery, one patient had a prothrombin test reduced below 45 % and in one patient there was a significantly reduced fibrinogen level calling for supplementation of this factor.
After improvement of the laboratory results and surgical treatment haemostasis returned to normal. All patients survived the operation and were discharged from hospital to domestic treatment.