[Pulmonary hypertension of the newborn - mechanisms of failed circulatory adaptation after birth, clinical presentation and diagnosis].

This article reviews the recent advances in understanding the mechanisms of the persistent pulmonary hypertension of the newborn, the pathways for persistence of high pulmonary vascular resistance and disruption of the normal perinatal fetal to neonatal circulatory transition. Despite the advancements of the neonatal intensive care in the last decades pulmonary hypertension of the newborn represents a clinical, diagnostic and treatment challenge for neonatologists. In most cases pulmonary hypertension is a secondary complication of a primary disease of the fetus and newborn characterized by failure to decrease the pulmonary vascular resistance after birth associated with right to left shunts, severe hypoxemia and respiratory failure. This review discuss the factors involved in the regulation of the transition from fetal circulation with high pulmonary vascular resistance to postnatal circulation with low pulmonary vascular resistance, the balance between the vasoconstrictor and vasodilator mediators. The better understanding of these mechanisms is helpful for accurate diagnosis and appropriate treatment of pulmonary hypertension of the newborn.