Atrial septal defects

Atrial septal defects


This is a communication between the two atria. It can be high in the atrial septum at the superior vena caval-right atrial junction, a sinus venosus defect; in the region of the foramen ovale, a secundum defect, and in the lower part of the atrial septum, a so-called primum atrial septal defect, which is described under the section on atrioventricular septal defects. With the exception of primum atrial defects, atrial defects are rarely predictable prenatally. The foramen ovale is always widely patent in the fetus and it is the failure of the flap valve to close off this defect postnatally which creates a secundum ASD. It appears impossible to predict this prenatally unless the foramen is very large, essentially in the setting of a common atrium. Atrial septal defects present during childhood with an asymptomatic murmur and signs of a left to right shunt at atrial level. They are readily successfully repaired surgically with excellent long-term results.


The normal foramen ovale occupies about one third of the atrial septum but with a large secundum atrial defect almost no atrial septum is seen. The atrioventricular valves are differentially inserted to distinguish this from a primum atrial defect which has different implications.

Differential Diagnosis

Care must be taken to differentiate a secundum ASD from a primum defect. The AV valves are offset in a secundum defect.

Sonographic Features

Almost no atrial septum is seen in the four chamber view.

Associated Syndromes

  • 4p-
  • 5p-
  • Chondroectodermal dysplasia (Ellis van Creveld)
  • Ehlers Danlos
  • Fetal alcohol
  • Fetal Valproate Effects
  • Goldenhar
  • Holt-Oram, Lithium
  • Noonans
  • Partial Trisomy 22
  • PKU
  • Rubella
  • Thalidomide
  • Treacher Collins
  • Triploidy and Diploid Triploid Mixoploidy
  • Trisomy 13
  • Trisomy 21
  • Trisomy 8 mosaic
  • Williams


  1. Beerman LB, Zuberbuhler JR In: Paediatric Cardiology Anderson RH, McCartney FJ, Shinebourne EA, Tynan M (Eds) Churchill Livungstone: Edinburgh,p541-563
  2. Feldt RH, Porter CJ, Edwards WD, Puga FJ, Seward JB In: Heart Disease in Infants, Children and Adolescents Adams FH, Emmanouilides GC, Riemenschneider TA (Eds) Williams & Wilkins: Baltimore, p170-189
  3. Muller LM, De Jong G, Van Heerden KM The antenatal ultrasonographic detection of the Holt-Oram syndrome South African Med J 68:313-5
  4. Ami M, Shalev E, Romano S, Zuckerman H Midtrimester diagnosis of endocardial fibroelastosis and atrial septal defect: a case report Am J Obstet Gynecol 155:662-3