Fig. 2. Pathophysiology of hemostasis abnormalities with extracorporeal circulation. Cardiopulmonary bypass crystalloid prime refers to the crystalloid solution necessary to prime the cardiopulmonary bypass circuit, whereas cardioplegia volume refers to the volume of crystalloid necessary for cardioplegic myocardial arrest. Contact activation via extracorporeal circulation (ECC) refers to contact activation related to interface of blood with nonendothelial surface of the ECC. Pericardial activation refers to activation of the hemostatic system via the tissue factor pathway mediated by transfusion pericardial blood containing tissue thromboplastin. Mechanical ECC refers to shear forces imposed by some of the components of the ECC circuit as listed tPA = tissue plasminogen activator; Gp = platelet glycoprotein receptors ( e.g. , IIb/IIIa or Ib).