The diagnostic hypothesis is based on the evidence that, while the functional closure of the PDA (Patent Ductus Arteriosus) occurs within a few hours after birth, anatomical closure may take several weeks. The functional closure of the PDA can be extremely sensitive to variations in blood oxygen tension and the hemodynamic instability of preterm infants. Therefore, echocardiographic evaluation and ductal diameter at a single point in time (such as during PDA echocardiography) may not correlate with transductal blood flow. Assessing the variation in the amount of pulmonary interstitial fluid using LUS (lung ultrasound score) could be an early predictive parameter for the closure or non-closure of hsPDA (hemodynamically significant PDA).

Inclusion Criteria:

• Neonates under 28 days of life
• Patients eligible for hsPDA closure treatment according to standard clinical practice

Exclusion Criteria:

• Neonates with congenital heart diseases (except for PDA and patent foramen ovale)
• Neonates with pneumothorax
• Neonates with pulmonary hemorrhage

Full-term and preterm neonates admitted to the aforementioned operational unit after birth, undergoing closure of the hsPDA (hemodynamically significant Patent Ductus Arteriosus) according to standard clinical practice.