Hamostaseologie
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The function of von Willebrand factor (VWF), a huge multimeric protein and a key factor in platelet dependent primary haemostasis, is regulated by its specific protease ADAMTS13. The ADAMTS13 dependent degradation of VWF to its proteolytic fragments can be visualized as a characteristic so-called triplet structure of individual VWF oligomers by multimer analysis. Lack of VWF high molecular weight multimers (VWF-HMWM) or their pathologically enhanced degradation underlies a particular type of von Willebrand disease, VWD type 2A with a significant bleeding tendency, and may also be observed in acquired von Willebrand syndrome due to cardiovascular disease. ⋯ The opposite condition, the persistence of ultralarge VWF (UL-VWF) multimers may cause the microangiopathic life-threatening disorder thrombotic thrombocytopenic purpura (TTP). During the course of active TTP, UL-VWF is consumed in the hyaline thrombi formed in the microvasculature which will ultimately result in the loss of UL-VWF and VWF-HMWM. Therefore, VWF multimer analysis is not a valid tool to diagnose TTP in the active phase of disease but may be helpful for the diagnosis of TTP patients in remission.
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Oral anticoagulants and platelet receptor blockers are widely used in clinical practice with the aim of reducing the risk of thrombotic complications in patients with cardiovascular diseases. Their regular intake and adequate antithrombotic action is vital and this is way numerous assays have been developed for laboratory testing and monitoring of these agents. ⋯ Such assays are increasingly used in clinical routine and their daily use is triggered by the advent of the novel direct oral anticoagulants (DOACs) as an alternative for vitamin K antagonist (VKA) treatment, which are dabigatran, rivaroxaban and apixaban, and by the advent of prasugrel or ticagrelor as an alternative for clopidogrel with regard to platelet P2Y12 receptor inhibition. In this review the most important and most commonly used laboratory assays are summarized as well as their clinical implications with the focus on DOACs as an alternative for VKAs and the different P2Y12 receptor blockers for antiplatelet treatment.
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Some cases of thrombotic microangiopathy (TMA) are refractory to plasma exchange therapy (PE) with persistence or recurrence of thrombocytopenia. We report two patients suffering from TMA of different aetiologies (associated with disseminated malignancy, typical haemolytic uraemic syndrome) with recurrent or persistent thrombocytopenia despite adequate therapy including PE. Since both patients were exposed to unfractionated heparin, heparin-induced thrombocytopenia (HIT) was suspected as a cause. ⋯ TMA might represent a predisposition for HIT. This could be due to TMA-related platelet activation with increased PF4 release. In TMA patients exposed to heparin and with refractory or rapidly recurrent thrombocytopenia HIT should always be considered as a possible cause.
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Both, severe haemorrhage and blood transfusion are associated with increased morbidity and mortality. Therefore, it is of particular importance to stop perioperative bleeding as fast and as possible to avoid unnecessary transfusion. Viscoelastic test (ROTEM® or TEG®) allow for early prediction of massive transfusion and goal-directed therapy with specific haemostatic drugs, coagulation factor concentrates, and blood products. ⋯ The Essener Runde task force is a group of clinicians of various specialties (anaesthesiology, intensive care, haemostaseology, haematology, internal medicine, transfusion medicine, surgery) interested in perioperative coagulation management. The ROTEM diagnostic algorithm of the Essener Runde task force was created to standardise and simplify the interpretation of ROTEM® results in perioperative settings and to present their possible implications for therapeutic interventions in severe bleeding. To exemplify, this text mainly focuses on coagulation management in trauma.