RecruitingPhase 3Drug trialPhase 3 Study on the Efficacy and Safety of Human Plasma Derived Antithrombin (Atenativ) in Heparin-Resistant Patients Scheduled to Undergo Cardiac Surgery Necessitating Cardiopulmonary BypassThe primary objective of this study is to evaluate the efficacy of two different doses of Atenativ, versus placebo, in restoring and maintaining heparin responsiveness in adult patients undergoing cardiac surgery necessitating cardiopulmonary bypass (CPB)