Magnetic Resonance Imaging for Cerebral Embolization During Minimal Invasive Mitral Valve Surgery

The purpose of this study is to prospectively evaluate major and minor neurologic events in patients undergoing right mini-thoracotomy mitral valve surgery and to compare different aortic clamping techniques; specifically, the endoaortic balloon with retrograde perfusion (Endoreturn) and the transthoracic clamp with retrograde perfusion. Major neurologic events will be evaluate through standard neurologic evaluation; minor neurologic events will be evaluate through magnetic resonance (MR) assessment. The first aim of the study is to determine the number and impact of microembolic events during right mini-thoracotomy mitral valve surgery on clinical neurological status and on MR evaluation. The investigators also aim to determine if different techniques of aortic clamping may impact on early outcome. Study hypothesis: despite recent concerns arising about endoaortic balloon with retrograde perfusion, the investigators expect to show equivalence in term of safety and effectiveness of this technique compared with the transthoracic clamp in a selected population.