Patent Ductus Arteriosus (PDA), Persistent

Key Features

Essentials of Diagnosis

• Continuous machinery type murmur

• Bounding peripheral pulses if large ductus present

• Presentation and course depends on size of the ductus and the pulmonary vascular resistance

• Clinical features of a large ductus

  • Failure to thrive

  • Tachypnea

  • Diaphoresis with eating

• Left-to-right shunt with normal pulmonary vascular resistance

General Considerations

• PDA is the persistence of the normal fetal vessel joining the pulmonary artery to the aorta

• Closes spontaneously in normal-term infants at 1–5 days of age

• Accounts for 10% of all congenital heart disease

• Incidence is higher in infants born at altitudes over 10,000 ft

• It is twice as common in girls than boys

• The frequency of PDA in preterm infants weighing < 1500 g ranges from 20% to 60%

• May occur as an isolated abnormality or with associated lesions, commonly coarctation of the aorta and VSD

Clinical Findings

• Depend on the size of the shunt and the degree of pulmonary hypertension

Moderate to large PDA

• Pulses are bounding, and pulse pressure is widened due to diastolic runoff through the ductus

• S1 is normal

• S2 is usually narrowly split.

• In large shunts, S₂ may have a paradoxical split (eg, S₂ narrows on inspiration and widens on expiration)

• Rough machinery murmur maximal at the second left intercostal space

  • Begins shortly after S₁, rises to a peak at S₂, and passes through the S₂ into diastole, where it becomes a decrescendo murmur and fades before the S₁

  • Tends to radiate well to the anterior lung fields but relatively poorly to the posterior lung fields

• A diastolic flow murmur is often heard at the apex

PDA with increased pulmonary vascular resistance

• Flow across the ductus is diminished

• S₂ is single and accentuated

• No significant heart murmur is present

• Pulses are normal rather than bounding

Diagnosis

Imaging

• Radiography

  • If the shunt is small, the heart is not enlarged

  • If the shunt is large, both left atrial and LV enlargement may be seen

  • Aorta and the main pulmonary artery segment may also be prominent

• Echocardiography

  • Provides direct visualization of the ductus

  • Confirms the direction and degree of shunting

Diagnostic Procedures

• Electrocardiography

  • May be normal or may show left ventricular hypertrophy, depending on the size of the shunt

  • Biventricular hypertrophy usually occurs in patients with pulmonary hypertension caused by increased blood flow

  • Pure right ventricular hypertrophy (RVH) occurs in pulmonary vascular obstructive disease

• Cardiac catheterization and angiocardiography

  • PDA closure in the catheterization laboratory with a vascular plug or coils is routine in all but the smallest of neonates and infants

Treatment

Medical