eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Atrial Septal Defect, General Concepts: Differential Diagnoses & Workup

Author: Michael R Carr, MD, Pediatric Cardiologist, Naval Medical Center Portsmouth
Coauthor(s): Brent R King, MD, Associate Professor of Emergency Medicine and Pediatrics, University of Texas Health Science Center at Houston; Chair, Department of Emergency Medicine, Memorial Hermann Hospital, Lyndon B Johnson General Hospital
Contributor Information and Disclosures

Updated: Oct 30, 2008

Differential Diagnoses

Atrial Septal Defect, Coronary Sinus
Atrioventricular Septal Defect, Partial and Intermediate
Atrial Septal Defect, Ostium Primum
Partial Anomalous Pulmonary Venous Connection
Atrial Septal Defect, Ostium Secundum
Pulmonary Stenosis, Infundibular
Atrial Septal Defect, Patent Foramen Ovale
Pulmonary Stenosis, Valvar
Atrial Septal Defect, Sinus Venosus

Workup

Laboratory Studies

  • In general, no specific laboratory studies are available to aid in the diagnosis of an atrial septal defect (ASD).
  • Determinations of brain natriuretic peptide (BNP) levels may be helpful in infants and in some children with large ASDs and congestive heart failure (CHF) when their clinical symptoms are equivocal. BNP levels are elevated in patients with CHF.

Imaging Studies

  • Plain radiographic findings in ASD are nonspecific but include right atrial and right ventricular dilatation, pulmonary artery dilatation, and increased pulmonary vascular markings. In general, an enlarged right atrium leads to overall cardiomegaly on the anteroposterior (AP) radiograph. Pulmonary artery dilatation results in a prominent hump between the aortic knob and the left ventricular contour on the AP radiograph. Although pulmonary vascular obstructive disease (PVOD) is rare, if it develops, the main pulmonary artery becomes large and the lung fields become oligemic.
  • Two-dimensional and Doppler echocardiography have revolutionized the diagnosis of ASDs. These studies can effectively reveal both the extent of the defect and the degree of left-to-right shunting. In small patients, the anatomy is observed especially well on subcostal views; the anomaly called deviated superior attachments of septum primum is reliably observed with only the modified subcostal left oblique view.
  • In older children, large adolescents, or adults, transesophageal echocardiography may be required to document an ASD because of limited transthoracic echocardiographic windows. This is particularly true if sinus venosus and unroofed coronary sinus type ASDs are present. Transesophageal echocardiogram may also be useful in small children with poor echocardiographic windows.
  • Cardiac MRI may be useful in the diagnosis of sinus venosus or coronary sinus defects in both children and older individuals with poor echocardiographic windows.
    • In experienced hands, cardiac MRI can easily depict anomalous pulmonary venous drainage associated with sinus venosus defects and a left superior vena cava, which is often associated with coronary sinus defects.
    • In general, older children do not require sedation for cardiac MRI (this is not the case with transesophageal echocardiography).
    • Cardiac MRI can also be used to calculate the effective left to right shunt (Qp:Qs) and quantitate right ventricular volumes.
    • It generally should not be used in attempts to further define atrial septal anatomy when entertaining the possibility of percutaneous device closure because transesophageal echocardiography defines the margins of the ASD much more effectively. Additionally, cardiac MRI is not readily available at all centers and requires a considerable amount of technical expertise.
  • CT angiography is a quick and effective means to identify pulmonary venous abnormalities associated with sinus venosus defects or to rule out suspected anomalous pulmonary venous return identified on echocardiography prior device closure. In children, similar to cardiac MRI, it is not an adequate modality to evaluate the atrial septal anatomy when assessing for the possibility of percutaneous closure. Additionally, CT angiography comes with the added side effect of radiation.
  • In some instances, cardiac catheterization is needed to provide further hemodynamic information prior to intervention. Pulmonary-to-systemic flow can be accurately determined when symptoms and results of other imaging modalities do not correlate. Additionally, calculations of pulmonary vascular resistance can be performed if pulmonary hypertension is a concern. Ideally, a mechanism should be in place to perform percutaneous device placement if the defect is suitable for closure at the time of the hemodynamic catheterization.

Other Tests

  • ECG most commonly demonstrates right-axis deviation, right ventricular hypertrophy, and an rSR' or rsR' pattern in the right precordial leads. The QRS duration is usually normal. However, the ECG may be normal, especially in infants and in young children with small defects (see Media file 8).
  • Left-axis deviation with a superiorly oriented counterclockwise frontal-plane loop suggests an ostium primum ASD (see Media file 9).
  • All types of ASD can result in prolonged PR intervals. This prolongation of internodal conduction may be related to the increased size of the atrium and a long internodal distance (which is a result of the defect).

Procedures

  • Cardiac catheterization is rarely necessary in the preoperative evaluation of a child with ASD.
  • Cardiac catheterization may be necessary if pulmonary hypertension is suggested to document PVR and to assess the response of PVR to vasodilator substances. It may also be necessary to evaluate associated lesions, especially in patients with more than one left-to-right shunt.
    • Findings on catheterization include a step-up in oxygen saturation from the superior vena cava to the right atrium (usually >10%), slightly increased right ventricular pressures, a small pressure gradient across the pulmonary valve (due to increased flow across a fixed valve orifice) and normal to mildly increased pulmonary artery pressures. If a large defect is present, the mean pressures in the right and left atria are identical.
    • The above being said, catheter-based interventions for the closure of selected secundum ASDs have become most common in pediatric patients. Although catheterization is rarely needed for diagnosis, it may be useful from a treatment standpoint. See Treatment for further details.

More on Atrial Septal Defect, General Concepts

Overview: Atrial Septal Defect, General Concepts
Differential Diagnoses & Workup: Atrial Septal Defect, General Concepts
Treatment & Medication: Atrial Septal Defect, General Concepts
Follow-up: Atrial Septal Defect, General Concepts
Multimedia: Atrial Septal Defect, General Concepts
References
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References

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Further Reading

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Keywords

atrial septal defect, ASD, congenital heart defect, ostium primum defect, ostium secundum defect, sinus venosus defect, coronary sinus septal defect, malalignment-type ASD, hypoplastic left heart syndrome, hypoplastic left heart syndrome, partial anomalous pulmonary venous connection, unroofed coronary sinus, congenital heart disease, atrial fibrillation, pulmonary hypertension, congestive heart failure, CHF, stroke, upper respiratory tract infection, pulmonary vascular obstructive disease, pulmonary artery hypertension, right ventricular hypertrophy, heart block, Down syndrome, hypertrophic cardiomyopathy

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Contributor Information and Disclosures

Author

Michael R Carr, MD, Pediatric Cardiologist, Naval Medical Center Portsmouth
Michael R Carr, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Cardiology, American Heart Association, and American Society of Echocardiography
Disclosure: Nothing to disclose.

Coauthor(s)

Brent R King, MD, Associate Professor of Emergency Medicine and Pediatrics, University of Texas Health Science Center at Houston; Chair, Department of Emergency Medicine, Memorial Hermann Hospital, Lyndon B Johnson General Hospital
Brent R King, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Pediatrics, American College of Emergency Physicians, American College of Physician Executives, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Paul M Seib, MD, Associate Professor of Pediatrics, University of Arkansas for Medical Sciences; Medical Director, Cardiac Catheterization Laboratory, Co-Medical Director, Cardiovascular Intensive Care Unit, Arkansas Children's Hospital
Paul M Seib, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, Arkansas Medical Society, International Society for Heart and Lung Transplantation, and Society for Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

Alvin J Chin, MD, Professor of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine
Alvin J Chin, MD is a member of the following medical societies: American Association for the Advancement of Science and American Heart Association
Disclosure: Nothing to disclose.

CME Editor

Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College
Gilbert Herzberg, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Chief Editor

Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine
Steven R Neish, MD, SM is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, and American Heart Association
Disclosure: Nothing to disclose.

 
 
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