Ductus arteriosus provides a detour for fetal blood to bypass fluid filled lungs and it closes functionally within hours after birth and structurally within the first few days of life.
Patent Ductus Arteriosus (PDA) remains a common problem for the pre term infant in whom it is more likely to remain patent or re-open after initial closure.
The incidence of PDA is inversely related with gestational age and varies from 20% in pre term infants> 32 weeks to 60% - <28 weeks gestation. Pre term infants with PDA are at increased risk of pulmonary congestion, hemorrhagic pulmonary edema, and chronic lung disease. Redistribution of systemic blood flow with shunts across PDA results in “diastolic steal” and decreased flow to major organs with higher risk of NEC, renal impairment, IVH.
Clinical features of symptomatic PDA include cardiac murmur, bounding pulses, widened pulse pressure, hyperactive pre-corduim, deterioration in respiratory status. However, clinical signs are poor at detecting PDA in the first 4 days of life with low sensitivity ranging from 37% to 72%.
Echocardiography is the method of choice for diagnosis of PDA and includes, demonstration of left to right shunt, ductal diameter> 1.5 mm, LA:Ao ratio> 1.5 and retrograde diastolic flow in the descending aorta exceeding 30% of antegrade flow. Recent advances include elevated cardiac natriuretic peptides in the presence of delayed closure of the ductus and may potentially be used as a rapid diagnostic tool.
Management strategies of the PDA include 3 broad groups: prophylactic “closure”, closure of the asymptomatic but clinically detected PDA and closure of the symptomatic PDA. Interventions include fluid restriction, use of diuretics, use of cyclo-oxygenase inhibitors and surgical closure.
Issues that will be discussed are: role of prophylactic versus symptomatic treatment of PDA, prolonged versus short course of indomethacin, ibuprofen vs. indomethacin, surgical treatment vs. indomethacin.
The neonatal clinician and echocardiographer must remain wary of occult congenital heart disease, particularly before closing the ductus. Infants with persistent patency of the ductus arteriosus beyond the early neonatal period should be followed closely during infancy.
|
