Prophylactic indomethacin: Factors determining permanent ductus arteriosusclosure

Background: Permanent closure of the ductus arteriosus (DA) requires both e ffective muscular constriction to block luminal blood flow and anatomic rem odeling to prevent later reopening. Objective: We examined the role of prophylactic indomethacin in producing p ermanent DA closure and the mechanism by which this occurs. Methods: We studied 2 separate approaches to managing a patent DA in 257 pr eterm infants (gestation 24 to 27 weeks): (1) prophylactic indomethacin tal l infants treated during the first 15 hours after birth) or (2 symptomatic treatment (infants in this group received indomethacin only if clinical sym ptoms appeared; infants whose ductus closed spontaneously and never receive d indomethacin were included in this group). Echocardiography was performed 24 to 36 hours after the last dose of indomethacin was administered or by age 5 days if spontaneous closure occurred, Infants were monitored for the development of ductus reopening. Results: The prophylactic treatment group had a greater degree of initial d uctus constriction, a higher rate of permanent anatomic closure, and a decr eased need for surgical ligation than did the symptomatic treatment group. The degree of initial ductus constriction was the most important factor det ermining the rate of ductus reopening. Post-treatment echocardiography prov ed to be the best test for predicting eventual reopening. Conclusion: Prophylactic indomethacin improved the rate of permanent duct n s closure by increasing the degree of initial constriction. Prophylactic in domethacin did nor affect the remodeling process, nor did it alter the inve rse relationship between infant maturity and subsequent reopening. Even whe n managed with prophylactic indomethacin, the race of ductus reopening rema ined unacceptably high in the most immature infants.