 Facing the lack of recommandations of Neurology and cardiology societies, the investigators decided in 2002 some Good Medical Practices to define a specific and precise population for whom the closure of permeable oval formaen after a first CVA seem to be necessary. Current survey of these patients after implantation of a prothesis in interauricular septum is defined by a consultation at 1, 3 and 6 months after surgery for a clinical exam and an echocardiography. One year after implantation, the investigators systematically realized a control by MRI associated to a contrast echography. 