Evaluate the Protective Effect of Conditioning With Sevoflurane on the Myocardium

Inclusion Criteria: * Patients who have provided informed written consent. * Aortic valve replacement via sternotomy or thoracotomy, under Cardiopulmonary bypass (CPB). * Anterograde cardioplegia with cold blood Exclusion Criteria: * Adults under guardianship. * Patients without national health insurance cover. * Epileptics. * Heart grafted patients. * Patients under 18 years and pregnant or beast-feeding women. * Aortic dissections and vascular surgery. * Contra-indications to treatment with Sevoflurane: hypersensitivity to halogen-based anaesthetic agents, myopathy, personal or family history of malignant hyperthermia, hyper-eosinophilia, liver disease, icterus or unexplained fever after anaesthesia with a halogen-based anaesthetic agent * Contra-indications to treatment with Propofol: known hypersensitivity to propofol or one of the constituents of the specific form used, hypersensitivity to peanuts or soja. * pre-operative LVEF\<35%. * Coronary artery bypass graft alone or associated. * Mitral valve replacements. * Warm cardioplegia.