Patent Ductus Arteriosus

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