Atrial septal defect (ASD) – Causes, Symptoms, Diagnosis, Treatment and Ongoing care



  • Congenital defect or opening in the atrial septum allowing flow of blood between the 2 atria
  • Shunting:
    • Typically left to right; occurs in late ventricular systole and early diastole
    • Degree depends on size of the defect and relative compliance (pressures) of the 2 ventricles
    • There can be minimal right-to-left shunting in early ventricular systole, especially during inspiration.
  • Asymptomatic early in life. Exertional dyspnea or fatigue. Late cyanotic shunt.
  • Types by location in the interatrial septum:
    • 75%: Ostium secundum defect occurs in the fossa ovalis region; most common and most amenable to percutaneous device closure
    • 10%: Sinus venosus defect occurs in the superior-posterior atrial septum near the orifice of the superior vena cava; usually associated with partial anomalous right upper pulmonary venous return
    • 15%: Ostium primum occurs in the inferior portion of the atrial septum, often associated with cleft mitral valve and failure of endocardial cushion development. Ostium primum also seen with incomplete persistent common atrioventricular canal.
  • Definitive diagnosis is by transthoracic echocardiography:
    • Symptomatic patients or patients with a high degree of shunt flow should undergo closure to reduce subsequent morbidity (right ventricular dysfunction and failure, atrial tachyarrhythmias, or stroke) and mortality. The risk of arrhythmias may not be decreased unless the atrial septal defect (ASD) is detected and corrected during childhood.
    • Surgery is the only option for ostium primum and sinus venosus defects.
    • Percutaneous closure is an alternative to surgical repair for patients with secundum ASD.
  • System(s) affected: Cardiovascular; Pulmonary

Pediatric Considerations

  • Most cases of ASD are detected in the pediatric population and corrected at that time.
  • Infants/children may just be small for their age, even in the absence of other symptoms.



  • Predominant age: Newborn, but may be diagnosed at any age
  • Predominant sex: Female > Male (2:1)
  • No race predilection
  • 4 per 10,000 births, or 1,574 cases per year, based on reporting on 11 US states 1999–2001 (1)


  • Accounts for 10% of congenital heart defects, and accounts for 25–30% of congenital heart defects detected in adulthood
  • Prevalence of asymptomatic patent foramen ovale in cohort of 2,291 adult patients undergoing cardiothoracic surgery—17.3% (2)[B]

Risk Factors

  • Other congenital heart defects
  • Family history
  • Thalidomide, alcohol


  • 5% chromosomal abnormalities
  • Ostium primum in Down syndrome


  • Flow across ASD based on relative compliance of left and right ventricles; therefore, usually left-to-right shunt because of higher left-sided pressures
  • Symptoms typically occur due to right ventricular and pulmonary vascular volume overload, sometimes with resultant pulmonary hypertension.

Commonly Associated Conditions

  • ASDs often may occur in the setting of other complex cardiac structural defects.
  • Important to exclude anomalous pulmonary venous return
  • Occasionally can indicate underlying genetic syndromes:
    • Holt-Oram syndrome: Secundum defect with bony abnormalities of forearms + hands
    • Ellis-von-Creveld syndrome: Chondroectodermal dysplasia + ASD
    • VACTERL:
      • V = vertebral abnormalities
      • A = anorectal malformation
      • C = congenital cardiac defects
      • T = tracheoesophageal fistula/esophageal atresia
      • R = renal–urinary defects
      • L = limb defects

Atrial septal defect, Congenital disorder, Paradoxical embolism, Dyspnea, ventricular systole, pulmonary venous return, tachyarrhythmias, ventricles, dyspnea, mitral valve, atrioventricular canal, atrial septal defect,



  • Easy fatigability, dyspnea on exertion, heart failure (late), palpitations, frequent respiratory tract infections
  • Stroke due to paradoxical emboli
  • Can be initially asymptomatic
  • Symptoms can include (but not limited to) easy fatigability, dyspnea on exertion, right heart failure (later during course of disease), palpitations, and frequent respiratory tract infections.
  • Other symptoms include stroke or unexplained end-organ infarcts due to paradoxical emboli.

Physical Exam

Signs vary according to extent of shunting:

  • Prominent precordial bulge
  • Right ventricular lift
  • Palpable pulmonary artery pulse
  • Fixed, widely split S2
  • Pulmonic flow murmur: Systolic ejection murmur
  • Low-pitched diastolic murmur at left lower sternal border
  • Cyanosis and clubbing (with severe pulmonary hypertension: Eisenmenger syndrome, jugular venous distention, edema)
  • Key physical finding: Fixed widely split S2
  • May have systolic ejection murmur (pulmonic flow murmur)
  • Prominent precordial lift
  • Low-pitched diastolic murmur at left lower sternal border

Diagnostic Tests & Interpretation


Oximetry: Cyanosis may suggest Eisenmenger syndrome (right-to-left shunting)

Initial lab tests

Electrocardiogram (ECG) findings:

  • General findings for secundum ASDs:
    • Right axis deviation
    • Right atrial enlargement
    • Right ventricular conduction delay
    • Q wave in lead V1
    • Mild PR prolongation
  • ECG findings for specific types of ASD:
    • Sinus venosus: Leftward axis, inverted P wave in lead III
    • Ostium primum: Leftward axis


Initial approach

  • Chest x-ray: Varying degrees of cardiac enlargement, increased pulmonary vascular workings, right ventricle and pulmonary artery enlargement
  • Echocardiography: Type and size of ASD, pulmonary arterial and right ventricular dilatation and anterior systolic (paradoxical) septal motion

Follow-Up & Special Considerations

  • Cardiac catheterization (indicated in select patients) demonstrates right ventricle enlargement and location of the shunt or if pulmonary hypertension is suspected.
  • Left ventricular angiography: Identifies prolapse of the mitral valve and allows assessment of the magnitude of the mitral regurgitation that might be present
  • Transesophageal echocardiography might be required to define ASD morphology and to locate the pulmonary veins.

Follow-Up & Special Considerations

  • Cardiac catheterization can be diagnostic (to assess anatomy, shunt fraction, and pulmonary vascular resistance) and therapeutic (for device closure).
  • Transesophageal echocardiography might be required to define ASD morphology and to locate the pulmonary veins, often as adjunct to percutaneous closure.

Diagnostic Procedures/Surgery

  • Echocardiography is the preferred noninvasive modality, unless patient body habitus prohibits adequate imaging.
    • A saline-contrast (“bubble”) study is needed only for diagnosis of patent foramen ovale (PFO), rather than hemodynamically significant ASD
  • Cardiac magnetic resonance allows excellent imaging and quantitation of shunt fraction.
  • Ultrafast computed tomography scans can also define ASDs, but with significant radiation exposure.

Pathological Findings

  • Gross defect in atrial septum
  • Dilated right atrium, right ventricle
  • Enlarged pulmonary artery

Differential Diagnosis

  • Other congenital heart disease
  • Right bundle branch block (for widely split S2)



First Line

  • Consider catheter or surgical closure of the significant ASD if pulmonary hypertension is not present.
  • May require antiarrhythmic medications for atrial fibrillation or supraventricular tachycardia
  • Respiratory tract infections should be treated promptly.
  • Proper treatment of heart failure

Second Line

  • There are no data to support antibiotic prophylaxis against infective endocarditis; however, when a device or patch is placed, prophylaxis is recommended until complete neoendothelialization of the foreign material occurs (usually 6 months).
  • To prevent thrombus formation after device deployment, aspirin 325 mg daily for 6 months and clopidogrel 75 mg for a month

Additional Treatment

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General Measures

75% of small ASDs (less than 8 mm) will close spontaneously by 18 months of age; however, close follow-up is warranted (3)[B]. Likelihood of spontaneous closure mainly dictated by diameter of defect: >10 mm at time of diagnosis—unlikely spontaneous closure (4)[B].

Issues for Referral

Appropriate health care: Referral to a cardiologist for evaluation

Surgery/Other Procedures

  • Closure via percutaneous transcatheter device or surgery (particularly when the pulmonary systemic flow ratio is ≥1.5:1 or evidence of right heart enlargement)
  • Percutaneous transcatheter device closure of secundum atrial septal defects and patent foramen ovale is now considered a standard and low-risk procedure that has largely replaced the surgical approach (5)[A].
  • Secundum ASDs that are suitable for percutaneous closure should be 35 mm or less in stretched balloon diameter and should have a sufficient rim of surrounding atrial tissue.
  • In children, closure is usually delayed until preschool age (2–4 years), except for symptomatic defects (poor growth or exercise intolerance).
  • In general, PFOs are treated differently from ASDs with significant shunt burden, and the benefits of PFO closure are unclear. Consultation with a neurologist and cardiologist may be considered prior to device closure. Closure in adult patients with stroke reduces the risk of further neurologic events (6)[B]:
    • PFO diagnosed intraoperatively not associated with any increase in risk of complications; closure at that time, however, increases risk of postoperative stroke vs unrepaired (7)[B].
    • Some evidence suggests possible symptomatic migraine relief following patent foramen ovale closure (8)[B], although this remains controversial and unproven.

Ongoing Care

Follow-Up Recommendations

Echocardiography follow-up

Patient Monitoring

  • In otherwise asymptomatic healthy children, follow until defect has closed or become negligible in size.
  • Appropriate evaluation and management for atrial tachyarrhythmias in patients with long-term follow-up
  • If ASD repaired as an adult, periodic long-term follow-up indicated
  • ASDs repaired in childhood generally do not have late complications.
  • Female patients with unrepaired ASD and Eisenmenger syndrome: Pregnancy not recommended due to increased risk of maternal and fetal mortality


Cardiac diet in patients with symptoms of cardiac failure, ascites, or edema

Patient Education

For patient education materials on this topic, contact American Heart Association, 7320 Greenville Avenue, Dallas, TX 75231, (214) 373-6300.


  • ASD closure in asymptomatic or minimally symptomatic adults reduces morbidity but not mortality (9)[A].
  • ASD closure before age 25 in symptomatic adults improves morbidity and likely reduces mortality, and some benefits may occur even in older patients. However, if ASD repair is deferred until after adolescence, the long-term risk of future atrial arrhythmias may not be decreased.
  • 50% mortality by age 50 in untreated symptomatic patients with large defects


  • Congestive heart failure
  • Late-onset arrhythmias 10–20 years after surgery (5%)
  • Stroke
  • Pulmonary hypertension
  • Eisenmenger syndrome
  • Infective endocarditis (ostium primum defects > ostium secundum defects)
  • Perioperative atrial tachyarrhythmias occurred in 10–13% of patients.
  • Device embolization (1%), cardiac perforation, thrombus formation, endocarditis, supraventricular arrhythmias postpercutaneous closure


1. Improved National Prevalence for 18 Selected Major Birth Defects – United States, 1999–2001. MMWR. 2006;54(51–54):1301.

2. Hart SA, Krasuski RA, et al. Incidence of asymptomatic patent foramen ovale according to age. Ann Intern Med. 2009;150:431–2.

3. McMahon CJ, Feltes TF, Fraley JK et al. Natural history of growth of secundum atrial septal defects and implications for transcatheter closure. Heart. 2002;87:256–9.

4. Hanslik A, Pospisil U, Salzer-Muhar U, Greber-Platzer S, Male C, et al. Predictors of spontaneous closure of isolated secundum atrial septal defect in children: a longitudinal study. Pediatrics.2006;118:1560–5.

5. Holzer R, Hijazi ZM. Interventional approach to congenital heart disease. Curr Opin Cardiol. 2004;19:84–90.

6. Onorato E, Melzi G, Casilli F et al. Patent foramen ovale with paradoxical embolism: mid-term results of transcatheter closure in 256 patients. J Interv Cardiol. 2003;16:43–50.

7. Krasuski RA, Hart SA, Allen D, Qureshi A, Pettersson G, Houghtaling PL, Batizy LH, Blackstone E, et al. Prevalence and repair of intraoperatively diagnosed patent foramen ovale and association with perioperative outcomes and long-term survival. JAMA. 2009;302:290–7.

8. Morandi E, Anzola GP, Angeli S et al. Transcatheter closure of patent foramen ovale: a new migraine treatment? J Interv Cardiol. 2003;16:39–42.

9. Attie F, Rosas M, Granados N et al. Surgical treatment for secundum atrial septal defects in patients >40 years old. A randomized clinical trial. J Am Coll Cardiol. 2001;38:2035–42.

Additional Reading

Lindsey J, Hillis L. Clinical update: atrial septal defect in adults. Vol 369 April 14, 2007.

See Also (Topic, Algorithm, Electronic Media Element)

Aortic Valvular Stenosis; Coarctation of the Aorta; Patent Ductus Arteriosus; Pulmonic Valvular Stenosis; Tetralogy of Fallot; Ventricular Septal Defect



  • 745.5 Ostium secundum, type atrial septal defect
  • 745.60 Endocardial cushion defect, unspecified type
  • 745.61 Ostium primum defect
  • 745.69 Other endocardial cushion defects


  • 70142008 Atrial septal defect (disorder)
  • 17718000 ostium primum defect (disorder)
  • 204315000 atrial septal defect within oval fossa (disorder)
  • 95268002 sinus venosus atrial septal defect (disorder)
  • 360481003 common atrioventricular canal (disorder)

Clinical Pearls

  • ASD is often missed due to subtle clinical presentation.
  • Ideally, hemodynamically significant ASDs should be closed in early childhood, though some benefit from closure also is present in older patients.
  • Many ASDs can be treated by catheter-directed percutaneous closure, rather than open-heart surgery.
  • Routine endocarditis prophylaxis is not recommended for isolated ASDs.
  • PFOs, unlike large ASDs, are very common and generally require no treatment in asymptomatic people.

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