Fontan is the most common procedure for single ventricle heart disease patients: it is a complex cardiothoracic surgery composed by three steps that must be carried out in the first years of life of children suffering from this congenital malformation. However, it is a palliative surgery which does not ensure a physiological circulation. Its success allows the patient to survive (especially in the first years of life), but its low efficiency can have bad consequences on future life. Because of its unique flow distribution, Fontan-treated patients are interesting cases to study from a haemodynamic point of view. In particular, computational models of Fontan procedure are powerful tools because they can provide an insight into complex flow phenomena, helpful to understand and improve this technique which is still imperfect.