Atrial septal defect

Atrial septal defects (ASD) are the second most common congenital heart defect after ventricular septal defects and the most common to become symptomatic in adulthood.

They are characterised by an abnormal opening in the atrial septum allowing communication between the right and left atria. Due to the low pressures of the atria, the lesion is typically asymptomatic until adulthood despite 2-4 times the normal pulmonary blood flow. Gradual (high output) congestive cardiac failure eventually develops, usually becoming symptomatic by the age of 30.

ASD accounts for ~10% of congenital heart disease 7. There may be greater female predilection.

Most patients are asymptomatic but as cardiac failure develops they may present with shortness of breath, palpitations and weakness 7

Classification

There are four major types of ASD 4, distinguished according to their location within the septum:

  • secundum ASD
    • 60-90% of all ASDs
    • usually an isolated abnormality
  • primum ASD
    • 5-20%
    • associated with cleft anterior mitral valve leaflet (partial atrioventricular septal defect)
  • sinus venosus
  • coronary sinus type ASD ("unroofed coronary sinus")
Associations

ASD's usually tend to be isolated anomalies, of which its associations include:

A patent foramen ovale (PFO) is a form of atrial septal defect.

Plain radiograph

ASD's do not cause any impairment in cardiac function in utero and even most neonates are asymptomatic. The defect can be closed surgically or percutaneously (e.g. using an Amplatzer closure device). However, careful evaluation has to be made to ensure lack of development of elevated right heart pressures or a right to left shunt before any intervention.  

Complications

In approximately 10% of untreated patients, pulmonary hypertension develops. In this situation, flow through the shunt eventually reverses and becomes right to left. The patient then becomes cyanotic. This is known as the Eisenmenger syndrome.

Other complications include:


Congenital heart disease

There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorised, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.

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Article Information

rID: 6294
System: Cardiac
Section: Pathology
Synonyms or Alternate Spellings:
  • Atrial septal defect (ASD)
  • ASD
  • Atrial septal defects

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Cases and Figures

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    ASD
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    Case 4: with closure device
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    Ostium secundum a...
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    Case 7: secundum ASD
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    Case 12: secundum ASD
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    Case 13: with pulmonary hypertension
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