Hemodynamic Stability During Carotid Endarterectomy.Comparison of LENOXe™ (Xenon 100% v/v) Versus Sevoflurane

Inclusion Criteria: * Patients \> 55 years, status ASA II * Carotid endarterectomy elected surgery * Signed informed consent Exclusion Criteria: Related to the patients: * Histories of hypersensibility in both products used in the study * uncontrolled arterial High Blood Pressure in the preoperative anaesthesia screening * Severe cardiac failure (FEVG \< 30 %) * Major lung or airways disease and\\or required per-operating FiO2\> 35 % * Elevated intracranial pressure * Pregnancy, breast feeding * Major protected, under supervision, under guardianship * Every patient entering within the framework of the contraindications indicated to §4.3 of the summary of the characteristics of tested products (LENOXe ™ (xenon 100 % v/v), sevoflurane) Related to the surgery: * Controlateral carotid stenosis superior to 70 % and\\or preoperative indication in the implementation per-operating of a carotid shunt * Surgery realized within the framework of an emergency * Combined Surgery