Non-Invasive Evaluation of Myocardial Stiffness by Elastography in Pediatric Cardiology (Elasto-Pédiatrie)

First, investigators must determine the physiological standards across age classes of myocardial stiffness estimated by Elastography in ultrafast (estimated right ventricular stiffness \[VD\] and left ventricular \[LV\]). This will be done in groups of children without heart condition, age group (10 children per group, four age groups \[0-1mois, 1 month-1 year 1 year-5 years, 5 years-15years\]). Secondly, investigators will evaluate myocardial stiffness Elastography (RV and LV) on different groups of children (same age group) with cardiomyopathy and examine correlations with the conventional parameters of systolic and diastolic function of both ventricles and with myocardial strain values. The total population of the study will be 120 children (40 healthy, 80 patients).