Congenital diaphragmatic hernia (CDH) is a developmental anomaly with a prevalence ranging between 1 and 4/10 000 births, hence qualifying as a rare disease (ORPHA: 2140). During embryogenesis the diaphragm fails to form [1], most often on the left side (85%), rarely on the right (13%), and sporadically bilaterally (2%). Exceptionally there is true agenesis of the hemidiaphragm, but most often the defect is confined to the posterolateral area (Bochdalek hernia). The anterior (Morgagni hernia; 30%) or central areas (2%) are less frequently involved [2]. Occasionally the diaphragm is intact yet thinned and devoid of muscular fibers, and is then called diaphragmatic eventration [3]. In case of a true defect, abdominal viscera can herniate into the thorax, acting as a space-occupying lesion that competes with the developing lungs. In left CDH (LCDH), this typically includes bowel, spleen, stomach, and less often the left lobe of the liver and rarely kidney. In case of a right-sided CDH (RCDH), the liver is virtually always into the thorax [4]. There can be also bowel and right kidney herniation. These structures compromise lung development, leading to variable degrees of pulmonary hypoplasia. The lung ipsilateral to the defect is most affected, however both lungs are in essence hypoplastic. They have a lower number of airways, fewer and smaller alveoli, thickened alveolar walls, and an increased amount of interstitial tissue [5]. This leaves less alveolar airspace, and hence reduces the gas exchange surface area. Parallel to airway changes, there is a similar reduction in arteries, essentially leaving a hypoplastic vascular bed. Morphologically, the vascular wall is thickened by an increase in the arterial media and adventitia, neo-muscularization of small pulmonary arteries [6, 7] and hypermuscularization of midsize and large vessels [8]. These vessels may have an abnormal response to mechanical and chemical stimuli in the postnatal period.