Neonates who underwent cardiac surgery with cardiopulmonary bypass almost always require non-invasive respiratory support (NIV) in relay to conventional ventilation. Current nasal interfaces do not generally allow synchronised bilevel ventilation. NIV-NAVA mode allows, through an oesophageal catheter, to record the electrical activity of the diaphragm and thereby synchronize breaths from the ventilator on the inspiratory efforts of the child. Moreover, the pressure support delivered by the ventilator may be proportional to the diaphragmatic effort developed by the child. This mode, associated with the interface Miniflow®, could increase the comfort of the child by allowing a more efficient synchronization and reducing its respiratory work. To our knowledge, this ventilation mode with this interface has not been evaluated in the postoperative period of cardiac surgery in the newborns. The purpose of this study is to evaluate the feasibility of this ventilatory mode and evaluate its influence on ventilatory parameters of this category of infants.