Coagulation in paediatric cardiac surgery

Abstract

Background: Surgical correction of congenital heart defects has a profound effect on the coagulation of the patients during and immediately after surgery. The aim of this thesis was to increase the knowledge of this effect, and to add to the work of establishing methods for treating this coagulopathy. Methods: Study I investigates the platelet response to paediatric cardiac surgery by analysis of platelet count and platelet aggregation measured with multiple electrode aggregation (MEA) before, during and after surgery. Study II measures the in vitro potency of the platelet inhibitor ticagrelor by measuring platelet aggregation using light transmission aggregometry and MEA. Study III compares MEA with a vasodilator activated phosphoprotein assay (VASP) before and after cardiac surgery. Study IV examines the coagulation in children with preoperative cardiac failure using rotational thromboelastometry. Study V is a method description of an ongoing study where patients are randomized to platelets or fibrinogen concentrate as the primary treatment of coagulopathy after cardiac surgery. Results: Platelet count and aggregation fall significantly during cardiac surgery, and impaired aggregation increases the risk of blood transfusion. The potency of ticagrelor in vitro does not vary with patient age. The correlation between MEA and VASP is poor. MEA results are similar in children with cardiac defects and healthy children. Preoperative cardiac failure does not have a significant impact on thromboelastometry results. Conclusions: Cardiac surgery in certain paediatric populations causes significant coagulopathy. Impaired platelet aggregation increases the risk of transfusion. Cardiac failure does not cause coagulopathy in infants. Ticagrelor potency is similar in patients of different ages.