Updated: 2/3/2019

Atrial Septal Defects

Review Topic
  • 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.
  • 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
    • 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
  • 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) 
  • 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
  • Electrocardiogram
    • indication
      • to assess for any arrhythmias
    • findings
      • right atrial enlargement
      • right bundle branch block
  • Making the diagnosis
    • based on clinical presentation and echocardiogram
  • 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
  • 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
  • Heart failure
  • Eisenmenger syndrome
  • Paradoxical emboli
    • venous emboli may run through ASD to become systemic arterial emboli

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Questions (4)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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(M1.CV.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? Review Topic

QID: 106811

Arteriovenous fistula




Pulmonary stenosis




Coronary artery disease




Pulmonary hypertension




Aortic root dilation




Select Answer to see Preferred Response


(M1.CV.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? Review Topic

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




Select Answer to see Preferred Response

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