Patent Ductus Arteriosus

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

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

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

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