Updated: 5/2/2021

Atrial Septal Defects

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Snapshot
  • A 15-year-old boy presents to his pediatrician’s office for exercise intolerance. He says he is unable to keep up with his friends during physical activities such as sports, which is new to him. On physical exam, a loud S1 and a fixed split S2 is appreciated during cardiac auscultation. He is sent for a chest radiograph, electrocardiogram, and echocardiogram for further evaluation.
Introduction
  • Clinical definition
    • a congenital defect resulting in an opening in the interatrial septum of the heart
  • Epidemiology
    • demographics
      • present at birth
    • risk factors
      • family history
      • exposure to alcohol or cigarette smoking in utero
  • Etiology
    • ostium secundum defect (most common)
      • secundum ASD is often an isolated congenital defect 
      • can result in paradoxical emboli from deep venous thromboses
    • ostium primum defect
      • primum ASD is often associated with other cardiac defects
  • Pathogenesis
    • atrial septal defect results from missing tissue rather than unfused tissue
    • left-to-right shunting in the heart, causing increased pulmonary blood flow and alterations in the pulmonary vasculature
      • over time, with severe defects, this eventually results in pulmonary hypertension and Eisenmenger syndrome
  • Associated conditions
    • fetal alcohol syndrome
    • Down syndrome
    • Patau syndrome
  • Prognosis
    • may be asymptomatic or may progress to heart failure
    • mortality highest in infants and adults > 65 years of age
Presentation
  • Symptoms
    • usually asymptomatic in childhood
    • patients with large ASDs will develop symptoms later in life
      • exercise intolerance
      • poor weight gain
      • frequent pulmonary infections
  • Physical exam
    • cardiac auscultation
      • loud S1
      • wide and fixed splitting in S2
      • parasternal heave
      • midsystolic pulmonary flow murmur (secondary to increased blood flow across the pulmonic valve) 
Imaging
  • Radiography
    • indication
      • often an initial test to rule out other pathologies
    • views
      • chest
    • findings
      • right heart enlargement
      • increased vascular markings
  • Echocardiography
    • indications
      • diagnostic test
      • most specific test
    • findings
      • ASD
Studies
  • Electrocardiogram
    • indication
      • to assess for any arrhythmias
    • findings
      • right atrial enlargement
      • right bundle branch block
  • Making the diagnosis
    • based on clinical presentation and echocardiogram
Differential
  • Ventricular septal defect
    • distinguishing factor
      • high-pitched and harsh holosystolic murmur
  • Aortic stenosis
    • distinguishing factor
      • paradoxical splitting of S2 (heard on expiration rather than inspiration)
      • crescendo-decrescendo systolic ejection murmur
  • Innocent/physiologic murmurs
    • distinguishing factor
      • most common murmur of childhood
      • grade < 2 intensity, minimal radiation, musical quality, softer intensity when sitting upright
Treatment
  • Management approach
    • mild defects can be left untreated
    • 6 months after procedures, patients must receive prophylaxis for infective endocarditis after dental procedures
  • Medical
    • palivizumab
      • indications
        • infants with symptomatic ASD
        • passive immunization against the respiratory syncytial virus (RSV)
  • Operative
    • percutaneous or catheter device closure
      • indication
        • smaller isolated effects
        • evidence of right heart overload
        • secundum ASD
      • complications
        • arrhythmias
        • thrombosis from the device
    • surgical repair
      • indication
        • shunt ratio > 1.5:1
        • primum ASD
        • evidence of right heart overload
Complications
  • Heart failure
  • Eisenmenger syndrome
  • Paradoxical emboli
    • venous emboli may run through ASD to become systemic arterial emboli

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