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Key Features

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Essentials of Diagnosis
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  • 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

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General Considerations
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  • 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

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Clinical Findings

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

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Moderate to large PDA

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  • 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

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PDA with increased pulmonary vascular resistance

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  • Flow across the ductus is diminished

  • S2 is single and accentuated

  • No significant heart murmur is present

  • Pulses are normal rather than bounding

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Diagnosis

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Imaging
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  • 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

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Diagnostic Procedures
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  • 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

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Treatment

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Medical
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  • Indomethacin, a prostaglandin synthesis inhibitor

    • Often used to close the PDA in premature infants

    • Does ...

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