Atrioventricular septal defects (AVSDs) comprise of a relatively
wide range of defects involving the atrial septum, ventricular
septum and one or both of the tricuspid or mitral valve. They
can represent 2 - 7% of congenital heart defects. The estimated
prevalence is at ~ 3 - 4 of 10,000 births. It results from
deficient development of the apical portion or the atrial
septum, basal portion of the inter-ventricular septum as well as
atrio-ventricular valves. All four chambers of the heart
communicate therefore both left to right and right to left
shunts can occur. Many have been used but can be broadly divided
into - Down syndrome - trisomy 21 : may be present in up to 50%
of cases 4 - trisomy 18 : may be present in up to 25 % of cases
ref. - Ivermark syndrome : may be present in up to 10% of cases
4 Plain film features are often not specific but may show have
cardiomegaly + / - features of pulmonary hypertension and mitral
valve insufficiency. Ultrasound - echocardiography / Allows
direct visualisation of the