The goal of the clinical trial is to evaluate whether a restrictive transfusion strategy adjusted by SvO2 during the perioperative period of cardiac surgery may reduce the incidence of red blood cell transfusion. Adult patients operated on cardiac surgery will be randomly allocated into two groups, one receiving standard restrictive transfusion, the other receiving SvO2 adjusted restrictive transfusion.The proportion of patients transfused will be compared between the 2 groups.

Cardiac surgery represents only a small fraction of all surgical procedures, but consumes a significant proportion of the stored red blood cells (RBC), with almost 50% of patients receiving a perioperative transfusion. Since RBC transfusion is associated with an increased risk of morbidity and mortality, blood patient management strategy has been promoted to favour prevention of anaemia, reduction of bleeding and limitation of transfusion. Current guidelines recommend haemoglobin (Hb) threshold as low as 7 g/dL, but still with a wide possible range (7 to 9 g/dl) and suggest that Hb alone may not be the best criteria for triggering transfusion. As Hb is an oxygen carrier, the rationale for RBC transfusion should be to increase tissue oxygen delivery. Central venous oxygen saturation (central SvO2), which is related to the balance between tissue oxygen delivery and consumption, is easily measurable in cardiac surgery. In a previous study, the investigators showed that in anaemic patients having undergone cardiac surgery, restrictive transfusion according to central SvO2 allowed a significant reduction in RBC transfusion incidence in the ICU. The investigators hypothesize that a restrictive transfusion strategy adjusted by SvO2 during all the perioperative period of cardiac surgery may reduce further the incidence of RBC transfusion. Limiting RBC transfusion to patients with a low SvO2 could save unnecessary transfusions, without increasing the anaemia related risk.

Inclusion Criteria:

• Aged above 18 years and under 85 years
• Signed informed consent form from the patient or his/her close relative or surrogate (if present) before inclusion or when possible when the patient has been included in an emergency setting
• Anaemic (Haemoglobin at inclusion ≤ 13 g/dL)
• Operated on elective, on-pump cardiac surgery for : Coronary artery bypass graft (CABG); Aortic, mitral or tricuspid valve (replacement or repair); Ascending aorta;Left ventricle assistance device (LVAD)
• Operated on urgent on-pump cardiac surgery for : CABG;Endocarditis;Aortic dissection; Heart transplantation
• Subjects must be covered by public health insurance

Exclusion Criteria:

• Patient with no central venous catheter inserted in the superior vena cava
• Pregnant or breast feeding patient
• Subject unable to read or/and write
• Participation in another interventional clinical trial or administration of an unapproved drug within the last 4 weeks before the screening date
• Medical history of heparin-induced thrombocytopenia contraindicating heparin use during surgery
• Persons deprived of their liberty by a judicial or administrative decision, persons undergoing psychiatric care and persons admitted to a health or social establishment for purposes other than research

Patients won't be aware of the assignment group