Inclusion Criteria:  Healthy volunteer subject between 18 and 30 years old patient with a regular sinus rhythm Echogenic subject. Fasting of solid and liquid since 8 h Subject in regular sinus rhythm. Written consent signed.  Exclusion Criteria:  Any known cardiac, renal or endocrine pathology. Arrhythmia rhythm disorder by atrial fibrillation Pregnant or nursing woman. Pathology versus indicating Nacl administration. Person under tutors or curators or deprived of liberty. Person not affiliated to a social security scheme.