CHD, congenital heart disease; LOE, level of evidence; MCV, mean corpuscular volume; PAH, pulmonary arterial hypertension; PDA, patent ductus arteriosus; PH, pulmonary hypertension; PPHVD, paediatric pulmonary hypertensive vascular disease; PVR, pulmonary vascular resistance; PVRI, PVR index; Qp, pulmonary blood flow; SVR, systemic vascular resistance; TIA, transient ischaemic attack; TPG, transpulmonary pressure gradient; VSD, ventricular septal defect; WU, Wood units.