Association of patent ductus arteriosus with fetal factors and endotypes of prematurity

Clinical and echocardiography predictors of response to first-line acetaminophen treatment in preterm infants with hemodynamically significant patent ductus arteriosus

OBJECTIVE

To assess clinical and echocardiography predictors of acetaminophen response for the treatment of patent ductus arteriosus (PDA) in preterm neonates.

STUDY DESIGN

Retrospective cohort study of preterm infants born <30 weeks, with a diagnosis of hemodynamically significant PDA, who received 1st line treatment with intravenous acetaminophen during the first 2 postnatal weeks. Response was defined by PDA closure or improvement in PDA score of >50%.

RESULTS

A total of 100 infants were included whose median weight and gestational age at birth were 663 grams and 24.6 weeks respectively. In total, 66 infants were classified as responders and were more likely to have intrauterine growth restriction, exposure to maternal hypertension and chorioamnionitis. Non-response was more common among infants with thrombocytopenia and anemia.

CONCLUSION

Responders were more likely to be IUGR with echocardiography indices of lower preload. Response to 1st line intravenous acetaminophen therapy is comparable to non-steroidal drugs in preterm infants. Relationship of response to acetaminophen to perinatal characteristics requires further characterization.

A novel role for PGE2-EP4 in the developmental programming of the mouse ductus arteriosus: consequences for vessel maturation and function

The ductus arteriosus (DA) is a vascular shunt that allows oxygenated blood to bypass the developing lungs in utero. Fetal DA patency requires vasodilatory signaling via the prostaglandin E2 (PGE2) receptor EP4. However, in humans and mice, disrupted PGE2-EP4 signaling in utero causes unexpected patency of the DA (PDA) after birth, suggesting another role for EP4 during development. We used EP4-knockout (KO) mice and acute versus chronic pharmacological approaches to investigate EP4 signaling in DA development and function. Expression analyses identified EP4 as the primary EP receptor in the DA from midgestation to term; inhibitor studies verified EP4 as the primary dilator during this period. Chronic antagonism recapitulated the EP4 KO phenotype and revealed a narrow developmental window when EP4 stimulation is required for postnatal DA closure. Myography studies indicate that despite reduced contractile properties, the EP4 KO DA maintains an intact oxygen response. In newborns, hyperoxia constricted the EP4 KO DA but survival was not improved, and permanent remodeling was disrupted. Vasomotion and increased nitric oxide (NO) sensitivity in the EP4 KO DA suggest incomplete DA development. Analysis of DA maturity markers confirmed a partially immature EP4 KO DA phenotype. Together, our data suggest that EP4 signaling in late gestation plays a key developmental role in establishing a functional term DA. When disrupted in EP4 KO mice, the postnatal DA exhibits signaling and contractile properties characteristic of an immature DA, including impairments in the first, muscular phase of DA closure, in addition to known abnormalities in the second permanent remodeling phase.NEW & NOTEWORTHY EP4 is the primary EP receptor in the ductus arteriosus (DA) and is critical during late gestation for its development and eventual closure. The "paradoxical" patent DA (PDA) phenotype of EP4-knockout mice arises from a combination of impaired contractile potential, altered signaling properties, and a failure to remodel associated with an underdeveloped immature vessel. These findings provide new mechanistic insights into women who receive NSAIDs to treat preterm labor, whose infants have unexplained PDA.