Evaluation of Haemate HS for the treatment of severe intraoperative hemorrhage during aortic-valve replacement in patients with aortic-valve stenosis

INTERVENTION: Intervention group: Intraoperative infusion Haemate HS 500/1000 IU (vWF/F VIII:C concentrate), time of infusion according to inclusion criteria. Control group: Intravenous infusion of 0.9% NaCl solution (100 ml) CONDITION: Severe intraoperative hemorrhage during aortic‐valve replacement ; Circulatory System ; Severe intraoperative hemorrhage during aortic‐valve replacement PRIMARY OUTCOME: Intra‐ and postoperative transfusion requirements according to defined transfusion thresholds. SECONDARY OUTCOME: 1. Requirement of rethoracotomy, assessed during patients stay at the intensive care unit ; 2. Surgeons' subjective rating of therapeutic efficacy after application of Haemate HS or placebo (classification of bleeding after therapy as "better", "equal" or "worse") ; 3. Survival (perioperative mortality, mortality during hospital stay, mortality within a 90 day period following surgery) ; 4. Duration of treatment on intensive care ward ; 5. Adverse events and therapy‐related side effects, assessed within the first 10 days after surgery. A second assessment is carried out after 3 month (at day 90) INCLUSION CRITERIA: 1. Patients with isolated valvular aortic stenosis or combined aortic‐valve defect with prevailing stenosis (mean transvalvular gradient >50 mmHg) with severe bleeding during aortic‐valve replacement 2. Age >18 years. 3. Written informed consent. 4. All patients that fulfill at least one of the following criteria 15 minutes after the end of extracorporal circulation and application of protamine: 4.1. Excessive bleeding without surgical explanation according to the surgeons' impression (Classification of bleeding as "normal", "moderate" or "excessive" by the surgeon. Classification as "excessive" bleeding leads to recruitment to the study). 4.2. Drainage volume >40 ml in 5 minutes following application of protamine and thorax closure.