Perioperative thrombotic complications in liver transplantation

Abstract

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 high-risk 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 occurring in 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.

Keywords: Vascular complications, Thromboembolic phenomena, Liver transplantation, Hepatic artery occlusion, Postoperative complications, Pulmonary emboli

Core tip: Data from many transplant centers demonstrate an underlying hypercoagulative state during liver transplantation. A dysfunctional hypercoagulable condition may persist for a variable time period after the transplant procedure. Occlusive vascular events deserve special attention because they pose a major threat to both patient and graft survival. Regardless of the lack of definitive guidelines on postoperative preventive antithrombotic treatment, many institutions recommend prophylactic anticoagulation in liver recipients at high risk of vascular thrombotic events. The present paper reviews the characteristics and risk factors of thrombotic complications after liver transplantation; in addition it presents valuable information on the relevance of pharmacologic thromboprophylaxis.