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Age-dependent closure of the patent ductus arteriosus by indomethacin
Insights
Indomethacin effectively closes the patent ductus arteriosus (PDA) in premature infants, but only those 33 weeks or younger respond fully. This suggests age is critical for successful PDA treatment with indomethacin.
Area of Science:
- Neonatal Medicine
- Pediatric Cardiology
- Pharmacology
Background:
- Patent ductus arteriosus (PDA) is common in premature infants.
- Indomethacin is a known treatment for PDA, but its efficacy by infant age is unclear.
Purpose of the Study:
- To determine the effective age range for indomethacin therapy in closing PDA.
- To investigate the relationship between infant age and response to indomethacin.
Main Methods:
- Studied 18 infants (4-45 days old) with clinical and radiographic evidence of PDA.
- Administered indomethacin (0.1-0.3 mg/kg) in two doses, 24 hours apart.
- Assessed PDA closure, murmur intensity, and heart failure improvement post-treatment.
Main Results:
- Complete PDA closure occurred in 8 of 12 infants aged 33 weeks or younger.
- Infants aged 34-36 weeks showed improvement but not complete closure.
- Infants older than 36 weeks did not respond to indomethacin therapy.
- Two patients experienced decreased murmur intensity and improved heart failure without complete closure.
Conclusions:
- Indomethacin therapy for PDA is most effective in infants under 33 weeks of gestational age.
- An age-related mechanism likely influences PDA closure, possibly involving prostaglandins.
- Treatment timing is crucial for successful indomethacin intervention in premature infants with PDA.
Abstract:
Indomethacin has been shown to be effective in closing a patient ductus arteriosus (PDA) in small premature infants. However, the age range over which this therapy is effective remains undetermined. Eighteen infants ranging in age from 4 to 45 days were studied. All had auscultatory and clinical findings indicative of PDA. Seventeen had roentgenographic evidence of cardiomegaly and/or increased pulmonary vascular markings, and eight had ECG evidence of ventricular hypertrophy. Indomethacin was administered to most patients in two doses of 0.1 to 0.3 mg/kg 24 hours apart. In eight of 12 patients, 3 week of age or younger, the PDA closed after indomethacin therapy. Two patients had a decrease in the intensity of murmur and improvement of congestive heart failure after treatment, but the PDA did not close completely. Only patients 33 weeks of age (actual age) or younger responded to indomethacin therapy with complete ductal closure. The condition of patients 34 to 36 weeks of age improved but there was not complete closure; in patients older than 36 weeks there was no response. The data suggest an age-related mechanism for PDA closure and that treatment with indomethacin before 33 weeks of age is probably required. A role for prostaglandin in ductal patency is postulated.