[Thrombosis and tissue protection in microvascular surgery--an overview].

Although microvascular surgery has become a safer procedure in recent years, failure still occurs. The main cause of failure is thrombosis of the anastomosed vessels. Thrombosis involves the vascular wall, platelets and the coagulation system. Sometimes the transferred tissue dies with the anastomoses open. This is caused by an insufficient perfusion at the microcirculatory level, e.g. a reduction of capillary inflow by arteriolar vasoconstriction. Tissue damage also occurs after ischemia and reperfusion. Oxygen free radicals and activated leukocytes are responsible for this phenomenon. Thrombosis can be reduced by antiplatelet and anticoagulant drugs, substances increasing fibrinolysis and other agents. In the clinical situation, aspirin, heparin and dextrane have proven reliable. The microcirculation can be protected by aspirin. Reperfusion injury is affected with superoxide-dismutase, allopurinol and perfusion solutions. Future developments in this field will include locally applied antithrombotic agents and substances acting more specifically.