A decrease in prostaglandin E2 (PGE2), along with exposure to oxygenated blood, causes the ductus arteriosus to close after birth.
PGE1 (0.1 ug/kg/min) maintains ductus patency (and in some cases can reopen a closed duct), by directly acting on vascular smooth muscle. PGE1 is essential in patients with HLHS, AS, interrupted arch, in which systemic DO2 is dependent on ductus flow. PGE1 can also be used to treat pulmonary hypertension, although it may be limited by systemic hypotension. Apnea and fever are other side effects. PGE1 can be used to diagnose duct-dependent lesions (a significant improvement in PaO2 following initiation of PGE1 is suggestive), although this technique may be less useful in the echocardiographic / fetal ultrasonographic era.
Several prostaglandins have been used via the inhaled route, with the hope of attenuating some of the systemic hypotension – prostaglandins which have been tried include PGE1, PGI2 (prostacyclin, aka epoprostenol/Flolan), and a stable analog of PGI2 (iloprost/Ventavis). Milrinone, NTG, NTP have also been used in the inhaled form. That said, the efficacy of any of these inhaled regimens has not been firmly established.
Side effects of prostaglandins include apnea and hypotension. Other side effects include fever, myoclonus, and irritability.
Prostaglandins in Congenital Heart Surgery
- PGE1: maintains ductus patency at 0.1 ug/kg/min. Can diagnose duct-dependent lesion (see Hallidie-Smith KA, below)
- PGE2: maintains ductus patency at in utero (PGE2 not available as a drug)
- PGI2: epoprostenol/Flolan
- PGI2 Analog: iliprost/Ventavis
- Hallidie-Smith KA. Prostaglandin E1 in suspected ductus dependent cardiac malformation. Arch Dis Child 59: 1020, 1984