Updated: 8/24/2018

Atrial Septal Defect (ASD)

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Snapshot
  • A 40-year-old man presents to his physician’s office for a routine physical. In the past few years, he has neglected to attend these appointments. He reports having no complaints, except for some shortness of breath with exertion. Physical exam reveals a new murmur, characterized by a wide and fixed split S2 heart sound, especially during inspiration. An echocardiogram reveals an atrial septal defect.
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
    • ostium primum defect
      • primum ASD is often associated with other cardiac defects
  • Pathogenesis
    • septa 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
      • systolic ejection murmur along the left upper sternal border
        • increase in flow over pulmonary valve
      • mid-diastolic rumble along the left sternal border
        • increase in flow over tricupsid 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
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 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 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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