Updated: 5/2/2021

Atrial Septal Defects

Review Topic
  • 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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(M1.CV.15.75) A 7-year-old girl is referred to a pediatric cardiologist after a heart murmur was auscultated during a routine school health examination. The patient has not experienced any symptoms of shortness of breath, fatigue, chest pain, or palpitations. She is healthy, does not have any significant medical history, and had an uneventful birth without any complications. Her vital signs are as follows: T 37.2 C, HR 92, BP 104/62, RR 24, SpO2 99%. Physical examination is significant for a midsystolic ejection murmur heard best at the 2nd intercostal space near the left sternal border, a loud S1 heart sound, a widely fixed split S2 heart sound, and no evidence of cyanosis or clubbing. An echocardiogram is conducted and reveals a left-to-right shunt across the interatrial septum. Surgical correction of this patient's condition will most likely prevent which of the following from developing later in life?

QID: 106811

Arteriovenous fistula



Pulmonary stenosis



Coronary artery disease



Pulmonary hypertension



Aortic root dilation



M 2 D

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(M1.CV.13.149) A 32-year-old woman presents to the emergency department with 2 hours of left-sided weakness. Her husband reports that she had been complaining of pain and swelling in her right calf for several weeks prior to this event. The couple had recently returned from a vacation in Europe. What ausculatory finding would explain the mechanism by which her more recent complaint occurred?

QID: 100665

Holosystolic murmur radiating to the axilla



Wide, fixed splitting of S2



Crescendo-decrescendo murmur heard loudest at the right second intercostal space



Holosystolic murmur that increases on inspiration



An S2 that splits during expiration



M 2 E

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