HF defines a condition in which the heart is unable to fulfill the body's need of blood supply. The reason of this inability is either known or idiopathic. Cardiac output is not only a sum of myocardial contractility, heart frequency, heart rhythm, preload and afterload, but is also related to contractile synchrony, interventricular interaction, as well as atrial-ventricular and ventricular-arterial coupling. Therefore, every single component or the sum of all components can lead to an insufficient heart function. Pediatric HF is related to genetic and metabolic abnormalities, structural diseases with volume or pressure overload, hypoxemia, arrhythmias or caused by myocardial disease. Clinical symptoms are dependent on the severity of HF, but also related to age and the cause of HF (1).New York Heart Association (NYHA) functional classification is not suitable to the young pediatric