Platelet And Coagulation Behaviour During Open Heart Surgery
Studies were undertaken in 19 patients (16 m, 3 f) having open heart surgery. Parameters investigated were: hematocrit; whole blood platelet count; β-TG levels in plasma and platelets; aggregation by ADP, adrenalin and ristocetin; glycoprotein analysis of whole platelets; plasma levels factor II, X, plasminogen (plg), antithrombin III (AT III) and α2antiplasmin (ap). Samples were taken before (1) and 5 min after induction (2), five min after opening the sternum (3), at aortic canulation (4), 15 min after start of extracorporeal circulation (5) and at release of aortic crossclamp (6). Measurements in 5 and 6 were corrected for dilution. Platelet count was decreased 20-30% in samples 5 and 6. There was a 350% increase in plasma β-TG levels in sample 6, without a change in the circulating-platelet β-TG content. The increase therefore appears to be due to destruction or release of the non-circulating platelets. ADP-aggregation was normal in all samples, Adrenalin and ristocetin aggregation was absent in samples 5 and 6 due to the pump priming fluid (haemaccel). However, in sample 4 aggregation induced by ristocetin (1 mg/ml) was also absent. This could not be explained by the presence of haemaccel or heparin. Absence of GP IB (the possible ristocetin receptor) also could not be demonstrated. Plasma II, X, pig, AT III and ap did not change in sample 1-4. Factor II and X decreased 8-9% in sample 5 and 6, whereas plg, AT III and ap resp. decreased 12, 14 and 20%. Evidently activation of the coagulation starts with the extracorporal circulation.