Ductus arteriosus closure — what closes it
Stimuli that close the patent ductus arteriosus at birth
Mnemonic device
Bradykinin-Oxygen-PG-down
Mapping
Bradykinin
Released as lungs inflate — promotes constriction
Oxygen
Rising PaO₂ post-first-breath — primary closer of the ductus
PG-down
Falling prostaglandin levels (placenta gone, no source) — releases the smooth muscle from PG-mediated relaxation
Clinical note: Therapeutic: prostaglandin E1 (alprostadil) keeps duct open in ductal-dependent congenital heart disease. Indomethacin closes it pharmacologically in patent-ductus-of-prematurity.