Perioperative thrombotic complications in liver transplantation

Although the perioperative bleeding complications and the major side effects of blood transfusion have always been the primary concern in liver transplantation(OLT),the possible cohesion of an underestimated intrinsic hypercoagulative state during and after the transplant procedure may pose a major threat to both patient and graft survival.Thromboembolism during OLT is characterized not only by a complex aetiology,but also by unpredictable onset and evolution of the disease.The initiation of a procoagulant process may be triggered by various factors,such as inflammation,venous stasis,ischemia-reperfusion injury,vascular clamping,anatomical and technical abnormalities,genetic factors,deficiency of profibrinolytic activity,and platelet activation.The involvement of the arterial system,intracardiac thrombosis,pulmonary emboli,portal vein thrombosis,and deep vein thrombosis,are among the most serious thrombotic events in the perioperative period.The rapid detection of occlusive vascular events is of paramount importance as it heavily influences the prognosis,particularly when these events occur intraoperatively or early after OLT.Regardless of the lack of studies and guidelines on anticoagulant prophylaxis in this setting,many institutions recommend such an approach especially in the subset of patients at high risk.However,the decision of when,how and in what doses to use the various chemical anticoagulants is still a difficult task,since there is no common consensus,even for highrisk cases.The risk of postoperative thromboembolism causing severe hemodynamic events,or even loss of graft function,must be weighed and compared with the risk of an important bleeding.In this article we briefly review the risk factors and the possible predictors of major thrombotic complications occurringin the perioperative period,as well as their incidence and clinical features.Moreover,the indications to pharmacological prophylaxis and the current treatment strategies are also summarized.