Contemporary Reviews in Cardiovascular Medicine Pathophysiology of Bleeding and Clotting in the Cardiac Surgery Patient From Vascular Endothelium to Circulatory Assist Device Surface

linicians are faced with the challenge of navigating theprecariousbalancebetweenbleedingandclotting.Bleedingdisordersorfailuretoobtainadequatehemostasisduringsurgerymay lead to severe hemorrhage. However, if thrombotic com-plications occur (eg, thromboembolic stroke), they may be farmore difficult to treat. To achieve a stable equilibrium betweenbleeding and clotting, the treating physician should have afundamental understanding of coagulation biology.Inthisarticle,wereviewthephysiologicalroleofthevascularendotheliuminmaintaininganantithrombogenicenvironmentatbaseline and a prothrombotic state after injury. Commonly usedhemostatic and anticoagulant drugs and their mechanism ofaction are examined in this context. This is followed by a reviewof the most common inherited and acquired bleeding andclotting disorders, as well as the mechanism by which they leadto defects in coagulation biology. The approach to a bleedingpatient is then discussed, including the interpretation of the mostfrequently used coagulation tests. Finally, we analyze mechan-ical assist device therapy as an extreme case of an acquiredbleeding and clotting diathesis.