Patent Ductus Arteriosus

Snapshot

• A 3-year-old boy presents to his pediatrician’s office for a well-child visit. He recently moved to the United States from Vietnam. He and his parents report no concerns. On physical exam, he is not in acute distress. His cardiac exam reveals a continuous machine-like murmur. There is no cyanosis or respiratory distress. The physician counsels the parents about this murmur and suggests an echocardiogram.

Introduction

• Clinical definition
  • a persistent opening between the aorta and pulmonary artery that fails to close in the immediate postpartum period
• Epidemiology
  • demographics
    • female > male 2:1
    • most commonly in premature infants
  • risk factors
    • maternal rubella infection
    • premature infants
    • in utero alcohol exposure
• Pathogenesis 
  • the ductus arteriosus is normal in utero and typically closes hours after birth
    • patency of PDA is maintained by prostaglandin E₂ (PGE₂) synthesis and low oxygen tension 
  • if unfixed, a large PDA can cause left-to-right shunting in the heart, which increases pulmonary blood flow and causes alterations in the pulmonary vasculature
    • shifting of blood from systemic circulation can cause cyanosis
    • over time, with severe defects, this eventually results in pulmonary hypertension and  Eisenmenger syndrome
• Associated conditions
  • fetal alcohol syndrome
  • congenital rubella
  • neonatal respiratory distress syndrome
    • due to persistently low oxygen tension
  • ventricular septal defect
• Prognosis
• typically progresses over time

Presentation

• Symptoms
  • symptoms usually occur with larger defects
  • respiratory distress
  • poor feeding
  • poor weight gain
  • easy fatigability
• Physical exam
  • cardiac auscultation
    • continuous “machine-like” or “to-and-fro” murmur 
    • 2nd intercostal space in the left upper sternal border
  • wide pulse pressure
  • bounding arterial pulses
  • cyanosis and clubbing of lower extremities 
  • signs of respiratory distress
    • tachypnea
    • grunting
    • nasal flaring
• retractions during breathing

Imaging

• Radiography
  • indication
    • for all patients
  • views
    • chest
  • findings 
    • enlarged pulmonary artery
    • increased pulmonary markings
    • cardiomegaly
• Echocardiogram
  • indication
    • performed as a diagnostic test
    • most specific test
  • findings
    • ductal flow
• increased left atrium to aortic root

Studies

• Electrocardiography
  • indications
    • to assess for arrhythmias
  • findings
    • left ventricular hypertrophy can occur over time
• Making the diagnosis
• based on clinical presentation and echocardiogram

Differential

• Ventricular septal defect 
  • distinguishing factor
• holosystolic murmur

Treatment

• Management approach
  • many lesions may close spontaneously
  • premature infants often need medical or surgical treatment
• Medical
  • indomethacin
    • indication
      • first-line therapy for all patients who do not need the PDA
      • premature infants with PDA
  • prostaglandin E
    • indication
      • for patients who require PDA to survive
        • e.g. for patients with transposition of the great vessels
• Operative
  • surgical closure
    • indication
      • failure of PDA to close after medical therapy
• term infants with large PDAs

Complications

• Heart failure
• Eisenmenger syndrome 
• Infective endocarditis