Adequate coagulation measured using activated clotting (ACT) is important during vascular and cardiac surgeries. Unfractionated heparin is the most common anticoagulant used. For point of care testing, under supervision of biology department, the investigators use Hemochron Signature Elite®(HSE) (Werfen®-Barcelona Spain) to determine coagulation during cardiac surgery under Cardiopulmonary Bypass (CPB), with arterial or venous blood. The dosage of heparin varies according to this result, throughout the CPB. On the Connect Manager® software (Livanova®, Italy) which records all the data of a CPB, it is mandatory to inform, during an ACT, the sampling site in arterial or venous. The chemical compositions of arterial blood and venous blood are different (O2, Co2…) Even if the qualities of coagulation in vivo are identical, what happens when they are chemically analyzed using the medical device HSE ? Can we trust the results of this device to secure anticoagulation under CPB? Are the results affected by the sampling site? The objective of this study is to compare the reliability of hemostasis control , during cardiac surgery under cardiopulmonary bypass, for both venous and arterial blood. Effective and controllable anticoagulation is mandatory during cardiac surgeries under extracorporeal circulation. The monitoring of the effectiveness of heparin is carried out, in our center, using the Hemochron Signature Elite® (HSE) medical device, which measures the ACT (Activated Clotting Time). There is no comparative study between hemostasis of venous blood, versus arterial blood, with this point of care device.

Inclusion Criteria:

• Patients aged 18 and over,
• undergoing conventional heart surgery under normothermic Cardiopulmonary Bypass (nadir 34°) (Aortic valve replacement, coronary artery bypass graft surgery, valve plasty, atrial septal defect, ventricular septal defect, intracardiac tumours, heart surgery, ascending aorta, combined surgery…)
• They must be affiliated with Social Security in France, and have given their written consent.

Exclusion Criteria:

• Minor Patients,
• Emergency Cardiac Surgeries, Extracorporeal circulation in hypothermia, Cardiac surgery without CEC
• Patients already included in a research protocol,
• Patient under guardianship or curators or deprived of public law,
• Patient with proven Heparin Induced Thrombopenia (HIT) not receiving heparin
• Pregnant woman, breastfeeding or parturient

Patients aged 18 and over, undergoing conventional heart surgery under normothermic Cardiopulmonary Bypass (nadir 34°) (Aortic valve replacement, coronary artery bypass graft surgery, valve plasty, atrial septal defect, ventricular septal defect, intracardiac tumours, heart surgery, ascending aorta, combined surgery…)