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Embryonic ductus arteriosus fails to close, resulting in continuous (systolic and diastolic) shunt of blood from aorta to left pulmonary artery (PA)
Usually located near the origin of the left subclavian artery
Effect of persistent left-to-right shunt on PA pressure depends on size of ductus
Small or moderate size patent ductus usually asymptomatic until middle age
Large patent ductus causes pulmonary hypertension, and Eisenmenger physiology may result
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Symptoms only if left ventricular (LV) failure or pulmonary hypertension develops
Heart size is typically normal or slightly enlarged
Hyperdynamic apical impulse
Wide pulse pressure and low diastolic pressure
Continuous rough "machinery" murmur
Thrill is common in upper right chest
Advanced disease: cyanotic lower legs (especially toes) in contrast to normally pink fingers due to reversal of shunt when pulmonary hypertension is present
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ECG: Normal tracing or LV hypertrophy
Chest radiograph
Normal-sized heart or LV and left atrial enlargement
Prominent PA, aorta, and left atrium
Echocardiography/Doppler
Can determine LV, RV, and atrial dimensions
Color flow Doppler allows visualization of the high velocity shunt jet into the proximal left PA
However, lesion is best visualized by MRI, CT, or contrast angiography
Cardiac catheterization can assess ductus and shunt size and direction
Invasive hemodynamic testing defines pulmonary pressures
Vasodilatory testing can be performed to see if the pulmonary hypertension is reactive
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Large shunts: high mortality early in life
Smaller shunts: compatible with long-term survival; heart failure most common complication
Antibiotic prophylaxis for dental procedures recommended to prevent endocarditis
Surgical ligation or, if ductus size is small enough, transcatheter closure using occluder devices
Ductus closure is usually attempted unless pulmonary hypertension and right-to-left shunting is present
Patients with an Eisenmenger physiology (shunt reversal) may benefit from vasodilator therapy
To monitor patients with shunt reversal, serial assessment of toe oxygen saturation can be used as a marker of improvement in the right-to-left shunt
On rare occasions, the ductus may become aneurysmal and require surgical repair