Atrioventricular septal defect (AVSD) – complete

Atrioventricular septal defect (AVSD) – complete


In this condition, there is a defect in the lower part of the atrial septum and the inlet part of the ventricular septum with a common atrioventricular junction. The common atrioventricular valve bridges the defect. The defect is commonly associated with Down syndrome or atrial isomerism, although it can occur with normal situs in patients with normal chromosomes. The patient usually presents early in life with signs of congestive cardiac failure or failure to thrive. Corrective surgery is usually satisfactory although mitral valve incompetence can be a complication. Surgical repair to the valve is usually performed at the initial surgery but if severe incompetence persists valve replacement may be necessary. This is always problematic in children as long term anticoagulation therapy is required as well as subsequent valve replacement with growth of the child. The longest results available for the repair of an atrioventricular septal defect are for 20-30 years and are satisfactory. This condition may have a higher rate of recurrence in offspring than other forms of heart disease.


The condition is readily detected echocardiographically due to the disruption of the normal appearance at the crux of the heart on the four chamber view. There is loss of the normal differential insertion of the two AV valves. One common valve bridges the defect in systole. In diastole, both atria communicate with both ventricles. There is a defect in the lower portion of the atrial septum, the primum septum and in the inlet portion of the ventricular septum. There may be AV valve regurgitation. The ventricular mass may be unevenly divided, resulting in left or right ventricular dominance.

Differential Diagnosis

If the ventricular component of the defect is very small, it can be mistaken for a partial defect. A defect in the inlet septum will also show loss of differential insertion but the primum atrial septum will be intact.

Sonographic Features

Atrial and ventricular defect at the crux of the heart Common AV valve Loss of differential insertion of the AV valves.

Associated Syndromes

  • Asplenia
  • CHARGE Assn.
  • Cri-du-chat 5p-
  • FAS (fetal alcohol syndrome)
  • Goldenhar
  • Holt-Oram
  • Polysplenia
  • Rubella
  • Thalidomide
  • Treacher-Collins
  • Trisomy 13
  • Trisomy 18
  • Trisomy 21
  • Wolf 4p-


  1. Anderson RH, McCartney FJ, Shinebourne EA, Tynan M (Eds) In: Paediatric Cardiology Churchill Livingstone: Edinburgh, p571-615
  2. Machado MVL, Crawford DC, Anderson RH, Allan LD Atrioventricular septal defect in prenatal life Br Heart J 59:352-355
  3. Allan LD, Sharland GK, Milburn A, Lockhart SM, Groves AMM, Anderson RH, Cook AC, Fagg NLK Prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus J Am Coll Cardiol 23:1452-8
  4. Allan LD, Sharland G, Cook A In: Color Atlas of Fetal Cardiology Mosby-Wolfe, London, p49-59