Cardiology · Congenital Heart Disease
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Patent ductus arteriosus results from the failure of the ductus arteriosus to close after birth, leading to a left-to-right shunt between the aorta and the pulmonary artery.
The classic physical exam finding is a continuous machine-like murmur best heard at the left infraclavicular area or second left intercostal space.
Patients often present with a wide pulse pressure and bounding peripheral pulses due to the continuous runoff of blood from the systemic circulation into the pulmonary circulation.
Premature infants are at the highest risk for symptomatic patent ductus arteriosus due to prolonged prostaglandin E2 exposure and immature ductal tissue.
Indomethacin or ibuprofen (cyclooxygenase inhibitors) are the traditional first-line drugs to promote ductal closure in premature neonates with a hemodynamically significant PDA, with acetaminophen a common alternative; each lowers PGE2 synthesis.
Surgical ligation or transcatheter closure is indicated for symptomatic infants who fail medical management or for older children to prevent Eisenmenger syndrome.
Congenital rubella infection is a classic maternal history association that increases the risk of developing a patent ductus arteriosus.
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A 3-week-old infant born at 28 weeks' gestation is being evaluated in the NICU for increasing oxygen requirement on CPAP, tachypnea, and feeding intolerance. On physical examination, the infant has bounding peripheral pulses, a wide pulse pressure, and a hyperdynamic precordium. Auscultation reveals a continuous machine-like murmur heard best at the left upper sternal border. Echocardiography shows a 2.5-mm ductus arteriosus with left-to-right flow, a left atrium-to-aortic root ratio of 1.8, and reversal of diastolic flow in the descending aorta. Renal function and platelet count are normal, and there is no bleeding or necrotizing enterocolitis. The team decides to attempt pharmacologic ductal closure.
The medications used for pharmacologic ductal closure in this infant act primarily by which mechanism?
Inhibition of prostaglandin synthesis (prostaglandin H2 synthase/cyclooxygenase), lowering PGE2, which maintains ductal patency
Bounding pulses, a wide pulse pressure, a continuous murmur, rising respiratory support, feeding intolerance, and echocardiographic findings of a large ductus with left atrial dilation and diastolic flow reversal indicate a hemodynamically significant PDA. PGE2 keeps the ductus open, and the preterm ductus is especially sensitive to it. The NSAIDs indomethacin and ibuprofen block the cyclooxygenase site of prostaglandin H2 synthase, and acetaminophen acts at its peroxidase site; each lowers PGE2 and promotes ductal constriction. Indomethacin and ibuprofen have similar closure rates (ibuprofen with fewer renal adverse effects), and acetaminophen appears comparable to ibuprofen in Cochrane reviews, so drug choice is individualized. Whether to treat at all is debated, because expectant management was noninferior to early ibuprofen in the BeNeDuctus trial (2023). Prostaglandin E1 (alprostadil) has the opposite effect and is used to keep the ductus open in ductal-dependent lesions.
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High yield triage
Etiology / Epidemiology
Failure of the ductus arteriosus to close after birth; highly associated with prematurity and rubella infection.
Clinical Manifestations
Presents with a machinery-like continuous murmur at the left upper sternal border and bounding pulses.
Diagnosis
Confirmed via echocardiogram showing continuous left-to-right ductal flow, with retrograde diastolic flow in the descending aorta.
Treatment
For a hemodynamically significant PDA in preterm infants, indomethacin or ibuprofen (or acetaminophen) lowers PGE2; per FDA labeling the NSAIDs are contraindicated with significant renal impairment, active bleeding, thrombocytopenia, or NEC.
Prognosis
Untreated leads to Eisenmenger syndrome and irreversible pulmonary hypertension.
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Epidemiology & Etiology
Common in preterm infants due to decreased sensitivity to oxygen-induced closure. Maternal rubella infection during the first trimester is a classic high-yield association. Female-to-male ratio is approximately 2:1.
Pertinent Anatomy
The ductus arteriosus connects the pulmonary artery to the descending aorta. It is essential for fetal circulation, bypassing the non-functional fetal lungs.
Pathophysiology
Post-birth, the drop in pulmonary vascular resistance and rise in systemic pressure normally triggers closure. Failure to close results in a left-to-right shunt from the aorta to the pulmonary artery. Chronic volume overload leads to left atrial and ventricular dilation, eventually causing pulmonary hypertension.
Clinical Manifestations
Classic machinery-like continuous murmur heard best at the left infraclavicular area. Patients exhibit wide pulse pressure and bounding peripheral pulses. Signs of heart failure include poor feeding, tachypnea, and failure to thrive.
Diagnosis
The echocardiogram is the preferred test for visualization and flow assessment. Chest X-ray may show cardiomegaly and increased pulmonary vascular markings. ECG often reveals left ventricular hypertrophy.
Treatment
In preterm infants with a hemodynamically significant PDA, pharmacologic closure may be attempted with indomethacin or ibuprofen (COX inhibitors) or acetaminophen; many centers favor expectant management for a less significant ductus because routine early treatment has not improved long-term outcomes (AAP 2016 clinical report; BeNeDuctus 2023; Baby-OSCAR 2024). Per FDA labeling, the NSAIDs are contraindicated with significant renal impairment, active bleeding, thrombocytopenia, or NEC. If medical therapy fails or the patient is symptomatic, transcatheter device closure (preferred beyond the neonatal period) or surgical ligation is the definitive treatment.
Prognosis
Small defects may be asymptomatic. Large, untreated shunts lead to Eisenmenger syndrome, characterized by cyanosis and reversal of the shunt. Long-term monitoring for infective endocarditis is recommended, particularly with a residual or unrepaired shunt.
Differential Diagnosis
Ventricular Septal Defect: Holosystolic murmur, not continuous
Aortic Regurgitation: Diastolic decrescendo murmur
Coarctation of the Aorta: Brachial-femoral pulse delay
Atrial Septal Defect: Fixed split S2
Truncus Arteriosus: Cyanotic heart disease