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Emergency and Acute Medicine – Patent Ductus Arteriosus
Patent ductus arteriosus (PDA) is a condition in which the fetal vessel connecting the pulmonary trunk to the descending aorta fails to close after birth. Normally, shortly after delivery, increased oxygen tension and changes in prostaglandin metabolism lead to ductal constriction, closure, and eventual fibrosis. In preterm infants, persistent patency may represent a physiologic and sometimes life-saving response related to hypoxia and immaturity. In contrast, persistence of the ductus in full-term infants represents a true congenital malformation due to structural deficiencies of the ductal wall.
As pulmonary vascular resistance falls after birth, blood is shunted from the aorta into the pulmonary artery, producing a left-to-right shunt. The magnitude of shunting depends on ductal size and the relative pulmonary and systemic vascular resistances, and in severe cases up to 70% of left ventricular output may pass through the ductus. Risk factors include prematurity, hypoxic conditions, high altitude, maternal rubella infection, and coexisting congenital heart disease, with a female predominance.
Clinical presentation varies with ductal size. Small PDAs may be asymptomatic, whereas larger shunts can lead to congestive heart failure, often within the first days of life. Typical findings include wide pulse pressure, a prominent apical impulse, a palpable thrill, and a characteristic continuous “machinery” murmur best heard at the second left intercostal space and radiating along the left sternal border. Additional features may include recurrent pulmonary infections and failure to thrive.
Diagnosis is primarily established through imaging. Chest radiography may be normal in infants but can show increased pulmonary vascular markings, cardiac chamber enlargement, and dilated great vessels in older patients. Electrocardiography may reveal left ventricular hypertrophy, with right ventricular hypertrophy indicating more severe disease. Echocardiography with Doppler is the diagnostic modality of choice, allowing visualization of ductal size, left atrial enlargement, and continuous aortic-to-pulmonary flow. Cardiac catheterization confirms shunting when needed and may be used therapeutically.
Management depends on patient age, symptoms, and ductal significance. Small, asymptomatic PDAs may be observed. In preterm infants, pharmacologic closure with prostaglandin synthesis inhibitors such as indomethacin is often effective during the first week of life. Full-term infants and children generally require definitive closure, as spontaneous resolution is rare; options include surgical ligation or transcatheter occlusion techniques. Supportive care includes oxygen for heart failure, fluid and sodium restriction, correction of anemia, and endocarditis prophylaxis when indicated.
Admission is required for patients with heart failure, pulmonary hypertension, or suspected endocarditis. Asymptomatic patients may be discharged with close cardiology follow-up and plans for elective closure. Key clinical points include recognition that heart failure may reduce renal perfusion and urine output, and that indomethacin therapy carries risks such as gastrointestinal bleeding.
Patent ductus arteriosus (PDA) is a condition in which the fetal vessel connecting the pulmonary trunk to the descending aorta fails to close after birth. Normally, shortly after delivery, increased oxygen tension and changes in prostaglandin metabolism lead to ductal constriction, closure, and eventual fibrosis. In preterm infants, persistent patency may represent a physiologic and sometimes life-saving response related to hypoxia and immaturity. In contrast, persistence of the ductus in full-term infants represents a true congenital malformation due to structural deficiencies of the ductal wall.
As pulmonary vascular resistance falls after birth, blood is shunted from the aorta into the pulmonary artery, producing a left-to-right shunt. The magnitude of shunting depends on ductal size and the relative pulmonary and systemic vascular resistances, and in severe cases up to 70% of left ventricular output may pass through the ductus. Risk factors include prematurity, hypoxic conditions, high altitude, maternal rubella infection, and coexisting congenital heart disease, with a female predominance.
Clinical presentation varies with ductal size. Small PDAs may be asymptomatic, whereas larger shunts can lead to congestive heart failure, often within the first days of life. Typical findings include wide pulse pressure, a prominent apical impulse, a palpable thrill, and a characteristic continuous “machinery” murmur best heard at the second left intercostal space and radiating along the left sternal border. Additional features may include recurrent pulmonary infections and failure to thrive.
Diagnosis is primarily established through imaging. Chest radiography may be normal in infants but can show increased pulmonary vascular markings, cardiac chamber enlargement, and dilated great vessels in older patients. Electrocardiography may reveal left ventricular hypertrophy, with right ventricular hypertrophy indicating more severe disease. Echocardiography with Doppler is the diagnostic modality of choice, allowing visualization of ductal size, left atrial enlargement, and continuous aortic-to-pulmonary flow. Cardiac catheterization confirms shunting when needed and may be used therapeutically.
Management depends on patient age, symptoms, and ductal significance. Small, asymptomatic PDAs may be observed. In preterm infants, pharmacologic closure with prostaglandin synthesis inhibitors such as indomethacin is often effective during the first week of life. Full-term infants and children generally require definitive closure, as spontaneous resolution is rare; options include surgical ligation or transcatheter occlusion techniques. Supportive care includes oxygen for heart failure, fluid and sodium restriction, correction of anemia, and endocarditis prophylaxis when indicated.
Admission is required for patients with heart failure, pulmonary hypertension, or suspected endocarditis. Asymptomatic patients may be discharged with close cardiology follow-up and plans for elective closure. Key clinical points include recognition that heart failure may reduce renal perfusion and urine output, and that indomethacin therapy carries risks such as gastrointestinal bleeding.
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