Fibrinogen function is impaired in whole blood from patients with cyanotic congenital heart disease.

BACKGROUND: Patients with cyanotic congenital heart disease (CCHD) have haemostatic abnormities associated with bleeding and thrombo-embolic events. The haemostatic abnormalities are not fully understood, but recent studies indicate that elevated haematocrit and fibrinogen function may be of importance. The aim of this study was to characterise the haemostatic profile and examine the potential role of haematocrit on clot formation and strength in CCHD patients. Furthermore to examine whether CCHD patients with history of haemoptysis have diminished fibrinogen function compared to those without haemoptysis. METHODS: In a prospective study 75 adult CCHD patients had haematocrit, platelet count, and plasma fibrinogen concentration examined. Furthermore thrombelastography(TEG) as well as TEG Functional Fibrinogen(TEG FF) assay evaluating fibrinogen function(FLEV) was performed. Data were compared with historical data regarding previous haemoptysis in CCHD patients. RESULTS: Haematocrit was 57 ± 8% and platelet counts in the lower normal range. TEG revealed a hypocoagulable condition with impaired clot formation. TEG values were correlated to haematocrit, indicating that elevated haematocrit causes impaired clot formation and strength. Despite high levels of plasma fibrinogen, TEG FF demonstrated that FLEV was diminished and negatively correlated to haematocrit. Furthermore CCHD patients with previous history of haemoptysis had significantly lower FLEV compared to CCHD patients without haemoptysis. CONCLUSION: Patients with CCHD are hypocoagulable mainly due to impaired fibrinogen function. Despite a low platelet count, platelet function does not seem to be severely affected in CCHD patients. Haemostasis, and especially fibrinogen function, is negatively affected by elevated haematocrit, and fibrinogen function is diminished in CCHD patients with haemoptysis.

Investigation of the thrombin-generating capacity, evaluated by thrombogram, and clot formation evaluated by thrombelastography of platelets stored in the blood bank for up to 7 days.

BACKGROUND AND OBJECTIVES: Transfusion based on the Thrombelastograph (TEG) results reduces transfusion requirements in cardiac surgery and in liver transplantation. Taking the pivotal role of thrombin generation in the coagulation process into consideration, the clinical utility of the TEG may, in part, depend on its reflection of the dynamics of thrombin generation. MATERIAL AND METHODS: The kinetics of thrombin generation of platelets stored for 2 and 7 days, respectively, was assessed by calibrated automated thrombogram (CAT) and the lag time (min), time to peak (ttPeak; min), peak (nm thrombin) and endogenous thrombin potential (ETP; nm thrombin*min) were registered. Clot formation was evaluated by TEG and the R time (min), maxial amplitude (MA; mm), time to maximum thrombus generation (TMG; min) and maximum thrombus generation (MTG; dynes cm(-2) s(-1)) and total thrombus generation (TTG; dyne cm(-2)) were registered. RESULTS: Platelets become more procoagulant, evaluated both by TEG and CAT during storage. The reduction in CAT lag time and the ttPeak correlated with a decrease in the TEG R time and TMG (P < 0.0001) as did the CAT peak thrombin generation and the TEG MTG (P = 0.0035). No correlation between ETP and TTG was found (P = 0.65). CONCLUSION: The kinetics of thrombin generation, as evaluated by CAT, correlates with the thrombus generation, as evaluated by thrombelastography and this may in part explain the clinical utility of the TEG in identifying clinically relevant coagulopathies, secondary to impaired thrombin generation.