Heart surgery is a considerable source of stress for the myocardium that must be minimized.

Troponin Ic is a reliable marker to determine the level of this myocardial stress.

Studies have shown that post-conditioning with AVH has a protective effect on the myocardium, if the treatment is initiated at the start of the ischemia.

The aim of this study is to evaluate the protective effect on the myocardium (by measuring troponin levels) of the association of pre-conditioning and post-conditioning with Sevoflurane (AVH) sedation administered during and after scheduled surgery for valve replacement, via sternotomy or thoracotomy compared with total intravenous anaesthesia with Propofol.

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.