AV septal defect 90% 50%
Atrial septum Functional common
atrium in 50%
Usually better
formed, intact in
20%
Atrioventricular
connection
Univentricular in
70%
Biventricular in
75%
Ventriculoarterial
connection
Concordant only in
4%
Concordant in
70%
Pulmonary
atresia/stenosis
80% 30%
Left-sided
obstruction
< 5% 30%
Heart
block/bradycardia
rare 70