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Key Features

  • 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

Clinical Findings

  • 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

Diagnosis

  • 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

Treatment

  • 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

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