The above recommendations of the European Paediatric Pulmonary Vascular Disease Network relate to the grading system currently suggested by the European Society of Cardiology (ESC) and the American Heart Association (AHA), and were based on paediatric data only (class, LOE). The complete list of references on the above subtopic can be found in ref. 24. COR, class of recommendation; CW, continuous wave; EI, eccentricity index; LOE, level of evidence; LV, left ventricle; PAAT, pulmonary artery acceleration time; PAP, pulmonary artery pressure; PE, pericardial effusion; PAH, pulmonary arterial hypertension; PH, pulmonary hypertension; PR, pulmonary regurgitation; RA, right atrium; RV, right ventricle; RVSP, right ventricular systolic pressure; S′, peak systolic velocity; SR, strain rate; TAPSE; Tricuspid annular plane systolic excursion; TR, tricuspid regurgitation; TTE, transthoracic echocardiography.