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An Atrial septal defect is a congenital congenital heart defect that causes a shunting of blood from the left to the right atria.

L-to-R shunt – ACYANOTIC
There are two types of Atrial Septal Defect:

  • Secundum ASD
    • 80% of ASD’s
    • Basically, a patent foramen ovale
  • Partial AVSD
    • Minority of cases
    • Usually involves a defect around the bottom of the atrial septum, and typically involves the tricuspid valve
  • Clinical features of both types are very similar
  • In both instances, blood will flow from left to right through the defect
 Atrial Septal Defect

Clinical features

  • Commonly asymptomatic
  • Recurrent chest infections / wheeze
  • Heart failure
  • Arrythmias – not until >4th decade of life


  • Split second heart sound
  • Ejection systolic murmur – best heard at the left sterna edge – due to increase bloodflow in the right ventricular outflow tract


CXRmay show cardiomegaly, and increased pulmonary markings
  • Secundum
    • RBBB (but this is common in many children anyway)
    • Right axis deviation
  • Partial AVSD
    • Left axis deviation
    • Superior QRS axis – the AVSD is typically in the region of the AV node, thus conduction is altered, and conduction occurs to the ventricles ‘superiorly’


Secundum ASD
  • Usually cardiac catheterisation. A device can be inserted to close off the defect

Partial AVSD

  • Surgery usually required
  • Usually performed at age 3-5 to prevent prevent RHF and arrhythmias in later life


  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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