The research aim is to validate a novel ground-breaking and easy-to-use EEG-based algorithm for sensing cerebrovascular accident (CVA) events under anaesthesia. Today there is no standard tool for CVA detection in anaesthetized patients. Thus the possibility of waking up from anaesthesia with severe brain damage is devastating. Patients undergoing cardiac surgery (such as valve replacement, CABG, thoracic aorta replacement, PTCA, TAVI (trans-aortic valve implantation)), carotid endarterectomy and surgery in sitting position, are at exceptionally high risk. We have developed a unique algorithm for detecting brain ischemia in anaesthetized patients, based on data acquired from 4 EEG electrodes. Our final goal is to develop a system that triggers an alarm when an ischemia occurs in an anaesthetized patient and during the peri-operative period.